What Dark Matter’s Alternatives Must Do

“The only relevant test of the validity of a hypothesis is comparison of prediction with experience.” -Milton Friedman

Dark matter is one of the most important components of the Universe today. And yet in the public’s eye, almost no one accepts it the way, say, the Big Bang is accepted. But it should be, and I’ll show you why.

Image credit: NASA / ESA / Marc Davis.

I’ve talked before about what it took to convince me that dark matter was the best theory out there (and gave a simpler version here), but — with alternative theories making big headlines — it’s important to truly know why dark matter is so successful and so thoroughly accepted by the scientific community, and why the alternatives really don’t stack up.

Image credit: University of Augsburg.

When you ask the question, “what’s the Universe made out of,” some part of that answer is obvious. There are atoms — protons, neutrons, and electrons — that make up, at a fundamental level, everything you’ve ever experienced here on Earth.

Image credit: Jerry Lodriguss and Andreas Gada.

There is light! Photons, coming from the Sun and the stars, not only come in visible wavelengths, but also in ones invisible to our eyes, from ultra-high-energy gamma rays down to ultra-low-frequency radio waves.

And there are some less obvious — but still detectable — things, such as neutrinos, heavy unstable particles (like the muon, tau, and Z-boson), and the quarks and gluons that come together to form the protons and neutrons themselves.

Image credit: Harrison Prosper at Florida State University.

And your first — and very reasonable — instinct would be to try and model our Universe as being made out of these constituents only, subject to our known laws of electromagnetism, nuclear and particle physics, and gravity. If our Universe is subject to these known laws and is made out of the stuff we know about, we should be able to be quite successful at modeling it so.

As a graduate student in physical cosmology, it was one of the first things I, personally tried to do. (Nearly a decade ago now; yikes!)

Image credit: Brooks/Cole Thomson Learning, retrieved from astronomyonline.org.

Now, here’s the truly interesting this: it doesn’t just fail, it fails spectacularly on a large number of levels.

It’s very frustrating, because these fundamental laws of physics are correct in every way that we’ve ever been able to test them. General relativity, quantum field theory, and classical electromagnetism have never failed us when they’ve been applied properly. And yet, something as simple as the shape of a spiral galaxy is unexplainable in this fashion.

Image credit: The Coma Cluster, retrieved from universe-beauty.com. The hi-res version makes some excellent desktop wallpaper.

So are galaxy clusters, in which the individual galaxies move far too quickly to be explained by this conventional, simplistic picture of the particles we know combined with the laws of physics that we know.

Image credit: Mark Subbarao, Dinoj Surendran, and Randy Landsberg for the SDSS team.

The large-scale clustering of galaxies in the Universe cannot be explained, either. We get a definitive set of predictions, and despite however we choose to tweak the densities of the various known particles, we cannot reproduce what is seen using the known particles and the known laws.

But it isn’t just the structure of the Universe.

Image credit: WMAP / NASA and Georgia State University.

The fluctuations in the temperature of the Universe don’t match up with any known way of tweaking these parameters. (In fact, the way to get closest is if you fill up the Universe with a huge percentage of neutrinos!) And in perhaps the most simple test…

Image credit: Ned Wright's cosmology tutorial.

How much hydrogen and helium are in the Universe? Given the amount of matter that we have, it won’t give us the right, observed ratio of hydrogen to helium if it’s all made out of “normal” stuff.

(There are plenty of other observational tests that fail to line up, including the unacceptably short lifetime of the Universe, but these are some of the major ones to look at.)

So we have a few options for things we can try, and they’re all dissatisfying at some level. Let’s look at the leading ones, plus one new one.

Image credit: Millenium Simulation, MPA Garching, V. Springel, S. White et al.

1.) There’s dark matter. Try throwing some cold (i.e., slow-moving) dark matter into your Universe, and it fixes all of these problems. The simulated clustering of galaxies (above) lines up with what we observe, the patterns of fluctuations in the microwave background suddenly match what theory predicts…

The predictions of gravitational lensing in clusters of galaxies — as well as the speeds of galaxies in clusters — match up with what we see, and the abundance of the light elements work out in an agreeable way with what the theory now predicts given the presence of dark matter…

Every galaxy gets outfitted with a halo of this dark matter, and this fixes the problem of it rotating (or winding up) too quickly on the inside. And when we apply the idea of dark matter to a very bizarre case, such as two colliding clusters of galaxies:

Image credit: X-ray: NASA/CXC/CfA/M.Markevitch et al.; Optical: NASA/STScI; Magellan/U.Arizona/D.Clowe et al.; Lensing Map: NASA/STScI; ESO WFI; Magellan/U.Arizona/D.Clowe et al.

Dark matter manages to correctly predict what we’ll observe even when the gravitational dark matter gets physically separated from the normal, light-producing matter!

In short, by adding this one novelty to the Universe — dark matter — we can suddenly solve all of these unexplained problems in cosmology.

But some people will never be convinced of this until we figure out what this dark matter actually is, and learn how to detect it directly, not merely indirectly via the influence of its gravity. And so we can try to consider other options.

Image credit: AAAS / Science, retrieved from francisthemulenews.wordpress.com.

2.) Modify the Laws of Gravity. The second leading option is to assume that there are no extra particles or sources of mass or gravitation in the Universe, but to assume instead that — on large scales in the Universe — the laws of gravity are different from Einstein’s General Relativity.

The one huge success of this is that this idea gives you the velocities within individual galaxies, and the predictions work in a superior fashion to those made by dark matter!

Image credit: Begeman, Broeils, & Sanders 1991; Sellwood & McGaugh 2005.

But modifying gravity does not explain any of the other observations sufficiently, or in the case of the microwave background and the light element abudances, at all. In addition, you have to give something up: general relativity.

Image credit: NASA, ESA, and Johan Richard (Caltech, USA); Davide de Martin & James Long (ESA/Hubble).

So in addition to all these things you still need to explain, you also need a new way of explaining all the things general relativity currently explains, such as gravitational lensing, shown above. Perhaps someday a modified theory of gravity will be able to sufficiently explain all of these things, and if so, it will be competitive with dark matter. But until it can do those things, it will (and should) be severely disfavored when compared with dark matter, the same way that a bowl of flour and sugar is disfavored when compared with a freshly baked cake.

And the new one

Image credit: USAF, retrieved from cosmos magazine.

3.) Maybe antimatter has negative mass. This one could, conceivably, explain the same things that dark matter does, although it would need to be worked out.

But you have to give up a ridiculous number of things that are known to be necessary, including:

E = mc2, or the equivalence between mass and energy. In other words, sometimes E = -mc2. The fact that positrons (anti-electrons) have been observed experimentally to be attracted towards (and not away from) the center of the Earth pretty much rules this one out.

But if this were true, then we would also have to accept that…

Image credit: Kim Kiminy.

You need to get rid of energy conservation! Not in the general relativistic sense, but in terms of fundamental particles and their interactions, which is hugely problematic, and flies in the face of every single high-energy physics experiment ever done!

(It would also violate the CPT theorem, which we believe is necessary for the Universe to exist the way that it does.)

Image credit: LANL.

It’s important to challenge the accepted model, to test it, poke at its holes and frailties, and to consider all conceivable alternatives.

But it’s also important to realize why it’s the accepted model, and that the alternatives fail so spectacularly. Rob Knop has taken a go at this as well, where he adds:

In the face of evidence otherwise, many still insist that most of the Universe must be made up of baryonic stuff that interacts with other baryons and our familiar photons. Is this not just as much hubris as insisting that the Earth, where we live, must be the center about which all the other Solar System bodies orbit?

And that’s why — despite some people’s predilections for denying dark matter — it really, truly, most likely exists, and the current challenge for cosmological physics is to figure out how to detect it. In the meantime, appreciate what we know and how we know it; it’s the only Universe we’ve got!

Comments

  1. #1 Mu
    August 18, 2011

    Very impressive write-up. Could you explain in a little bit more detail why MOND and GR are mutually exclusive? It’s that “either-or” choice that makes it so hard to discard either MONDs beautiful modelling of the galactic rotation or the dark matter predictions for large structures etc.

  2. #2 Juice
    August 18, 2011

    What’s wrong with looking at dark matter as an extremely useful fudge factor? Until it’s discovered what it might be or what’s wrong with the current model (GR, QM), that’s what it seems to be for me. For me it’s the modern epicycle. I mean, don’t people have enough trouble solving an n-body problem using only Newtonian gravitation?

  3. #3 Ethan Siegel
    August 18, 2011

    Mu,

    Very briefly, MOND says that at small accelerations (which corresponds to galactic-scale or larger distances), there is some “extra” fundamental acceleration that must exist. This violates the equivalence principle (and a host of other things), but gives the right shape for galactic rotation curves. It also mean that — on galactic-scale-or-larger scales — gravitation works differently than standard GR predicts.

    This is a tremendous difficulty for large scale structure, the CMB and gravitational lensing, which MOND (and its relativistic variant, TeVeS, which I swear should be called STeVe) has thus far failed to address.

    Juice, it could be a fudge factor, but it works so well for such a simple assumption that it really is that compelling.

  4. #4 Juice
    August 18, 2011

    Epicycles worked really really well. So well that people assumed it had to be correct. They made the math more complicated though, not less. Ok, and eventually they didn’t work at all once measurements became more accurate centuries later. Hopefully we don’t have to wait centuries to find out if dark matter exists or not.

  5. #5 Rob Knop
    August 18, 2011

    I think the Dark Matter/epicycle comparison is also off base. Indeed, it’s often the alternatives to Dark Matter that need to get all “fine tuney” to make things work. Dark Matter isn’t a case of having to add fine tuning correction after fine tuning corretion; it’s adding one big thing that makes many of us (Ethan once included, and myself also included for a while back in grad school) feel uneasy, but which explains a wide range of observations.

    Dark Energy, on the other hand, is something that might be along the lines of an epicycle– adding something that is really a pointer to our having reached the limit of our current theory. I know that Sean Carroll has done some thinking about this particular topic, and when I last talked to him about it (admittedly several years ago), he said that efforts to get rid of Dark Energy by fiddling with General Relativity tended to be very “fine tuney” and contrived, undermining any Occam’s Razor or aesthetic value in using them rather than Dark Energy.

    BUT, that’s Dark Energy. Dark Matter is in a a FAR firmer footing than Dark Energy. With Dark Energy, we know something’s going on; with Dark Matter, we’re very sure that there’s stuff that is non-baryonic.

  6. #6 Rob Knop
    August 18, 2011

    Another note in response to Juice: there’s no problem solving the n-body Newtonian problem.

    It is true that it can’t be solved; how can you resolve this with my just having said that there’s no problem solving it? When I say that the n-body problem “can’t be solved”, I mean that there is no simple algebreic closed-form solution for it, the way that there is for the general two-body Newtonian problem. (That generic form is still mathematically advanced enough that usually physics majors don’t see it until their junior or senior years; simplified special-case versions of it, however, are included in physics and astronomy classes for non-majors.)

    It’s not that the n-body problem isn’t solved in that way, it can’t be solved in that way. On the other hand, there is a whole industry of people who calculate numerical solutions of the Newtonian n-bopy problem. This means doing a tremendous number of relatively simple calculations… something that computers excel at. For a comprehensive introduction to this form of numerical astrophysics designed for pretty much any non-innumerate college student who’s been through basic physics, I would point you to Piet Hutt and Jun Makino’s Moving Stars Around.

    So, the n-body problem is solved. While it’s correct to say that it “can’t” be solved, and while working on solutions of it has been and continues to be an active area of computational astrophysics, in no way does this represent any kind of “trouble” for Newtonian gravitational theory.

  7. #7 maxwell
    August 18, 2011

    Hey Ethan,

    do you have any recommendations on grad level quantum field theory texts that an theoretical optical physicist might find handy in presenting the real theory behind dark matter?

    Thanks.

  8. #8 Collin
    August 19, 2011

    I think the real problem I have with dark matter is what the name itself connotes. Assuming we totally reject the idea of negative mass (which I find quite silly — upsidasium, anyone?), the ancient idea of matter as an absolute category is false. In common parlance, matter is just a type of energy that happens to be self-cohesive, and anything more specific is basically just a list of known states of matter.

    In a self-consistent MOND-like extension of general relativity (which I don’t think has been proposed yet, although TeVeS is close), there would be such a collection of energy. And this begs the question what is it about such hypothetical energy that would qualify it as not being a new form of matter?

    Conversely, what does the accepted theory of dark matter say mathematically that corresponds to calling it matter? Please be specific. I’m not afraid of math, I know basic algebra and calculus, and I know what a tensor is.

    Sincerely,
    Collin

  9. #9 Alan L.
    August 19, 2011

    MOND as a theory lacks plausibility. However, likes or dislikes are irrelevant where science is concerned.

    Given that:

    (1) MOND involves an unsatisfactory, ad hoc tweak to standard gravitational calculations, a fudge factor with no underlying theory to support it;

    But also given that:

    (2) despite its implausibility MOND explains galactic rotations better than the Invisible DM theory, as currently understood.

    Has any scientist ever addressed the question of what this reveals about the properties of Invisible DM? In other words, what physical property would a collection of DM particles need to possess to make an ad hoc theory like MOND appear to be true?

  10. #10 Sascha Vongehr
    August 19, 2011

    Ethan, I think one of the big problems with the public acceptance is the presentation of dark matter and dark energy as if they are two ad hoc thingies out of thin air waiting to be joined by the dark force or whatever comes next. That is why I find it important to firstly make sure that people understand the big difference between dark matter and dark energy – that is more than half the battle. I did this before here
    http://www.science20.com/alpha_meme/not_afraid_dark_dark_energy_ultimate_sisyphus
    but you triggered me to write something yet simpler once more today
    http://www.science20.com/alpha_meme/dark_energy_dark_matter_dark_force_not_afraid_dark-81831
    – please let me know what you think about this approach.

  11. #11 psmith
    August 19, 2011

    Thanks for your usual lucid explanations.

    Are there any ideas about how dark matter might have formed out of the Inflation/Big Bang process?

  12. #12 SLC
    August 19, 2011

    It should also be pointed out that abandonment of energy conservation would imply that the invariance of the laws of physics under static time translations also would have to be abandoned. If the laws of physics are time dependent, we are in big trouble.

  13. #13 mf
    August 19, 2011

    so the observation is, that rotationl velocity of galaxies saturate with distance, instead of increasing as they should without dark matter. If dark matter is an explanation, then there needs to be a specific and universal density distribution of dark matter in galaxies. I could buy the dark matter explanation if the observation was that the rotational velocity curve deviates from expectations in a random fashion ,which means rotational velocities deviate rather than saturate as shown in the plot above. If the saturation is truly universal, there is a law of nature that is being missed here.
    The author also says that the “big bang theory is universally accepted”. Not by me it is not. I cant speak for others. Big Bang theory failed repeatedly ,and it has been “fixed” by ad hoc assumptions, like inflation, which in my mind amount to the following: lets suspend known laws of physics until the initial state of the universe matches what we observe, at which point we say that Big Bang theory agrees with all observations. This is not science, it is a quasi religious belief wrapped in scientific clothing. I started my career in particle physics ,now I live among biologists and doctors. people here, frustrated by complexities of biology, have the following motto: “with three adjustable parameters, I can make elephants fly”. Physicists, and in particular astrophysicists, would do well to heed this warning.

  14. #14 Eric Lund
    August 19, 2011

    Alan @8: If you take general relativity as a postulate and the rotation curve for a particular galaxy as data, you can, at least in principle, compute the radial distribution of mass that would produce that rotation curve. To first order, the distribution of dark matter plus baryonic matter that comes out of the constraints produced by other phenomena that dark matter explains is a good approximation for the actual required distribution.

    I’m not familiar with MOND theories, so I don’t know what free parameters there are in the model or how sensitive the model is to adjusting those parameters. But it’s a safe bet that the curve Ethan shows is based on some “best fit” of those parameters to some data set. Yes, MOND does that well. The point is that MOND doesn’t do anything else well. It’s like phlogiston: that theory was adequate (at least for measurements then available) for explaining combustion but was a failure at explaining why metals rust. We now know that reaction with oxygen in the air accounts for both combustion and rusting.

    FWIW, “mond” is the German word for “moon”. Was the term MOND coined by critics of the theory (as Hoyle did with the “Big Bang”) as an attempt at ridicule? IOW, “You’d have to be a lunatic to believe this theory”–the word “lunatic” is derived from the Latin word for moon”.

  15. #15 Mark in DC
    August 19, 2011

    It saddens me to read such a brilliant and well-studied person make such an unscientific and, frankly, absurd claim:

    “And that’s why — despite some people’s predilections for denying dark matter — it really, truly, most likely exists, and the current challenge for cosmological physics is to figure out how to detect it…”

    Most likely? Truly – most likely?

    There is absolutely no SCIENTIFITC reason why ‘dark matter’ MUST BE or should be the most accepted model. There is absolutely no empirical evidence that dark matter (what a horrible name – why not merely call it God’s magic matter?) exists. And until that time there should be NO accepted model. PERIOD.

    Yes, ‘dark matter theory’ should be pursued and investigated and tested and whatever else is needed. BUT until the theory is VALIDATED, there is no reason, unless one is a dogmatic atheist bent on proving there is no God, to teach or proclaim or demand that ‘dark matter theory’ be held in any higher esteem than any other theory that is credible and worthy of being validated.

    Great advances in scientific thought are being stifled by the too numerous number of practitioners who have forced their dogmatic atheistic faith into the realm of scientific enquiry.

    And it would also be helpful if our universities started teaching students of science the meaning of ‘validity’ and the essential and necessary role that validity and logic play in all scientific enquiries. Of course the atheist crowd resists that as logic is so often an enemy of their blind and irrational faith.

  16. #16 Troy
    August 19, 2011

    A problem is this may be the only universe we have but not the only one there is. Theories on that this kind of scale would probably have to address that issue as well

  17. #17 Steve
    August 19, 2011

    Dark matter is far from a single solution to our cosmological problems. To make everything work, we need dark matter to cause additional gravitational attraction. But then we need dark energy to create repulsion to compensate for having too much attraction from dark matter.

    I think you are too quick to dismiss alternative theories. I think MOND speaks for itself and others have already posted its superlatives.

    However, antigravity is more complicated than you suggest. First, as far as E=-mc2, this is already true. Antimatter arises from the negative energy solutions of the Dirac equations, which is exactly what you have here.

    Second, no experiement to date has accurately measured the gravitational force between matter and antimatter. To suggest that it’s well understood that positrons are attracted to the Earth is overstating the experimental results.

    Third, it was believed that antigravity violated CPT. These results were based on gedenkin type analysis. A more recent analysis of CPT and gravity actually leads to the prediction that antigravity is consistent with CPT and that matter-antimatter gravitational attraction would violate CPT.

    The biggest problem with dark matter/energy is that it’s just too convenient. Whatever gravitational effect you observe, we can create a distribution of matter/energy so that our current theories make correct predictions. At some point this seems like putting more and more gears on the celestial sphere. Every time we find something is a little off, we just add a small gear. With the lack of direct evidence of dark matter/energy for the past 20 years, coupled with the increasing need to tweak the distribution to fit the data, people are beginning to critically rethink the theory.

  18. #18 Doug Little
    August 19, 2011

    I got a question, how does dark matter jive with string theory? Could dark matter exist in higher dimensions and so cannot be detected, except via it’s gravitational effects. Could it be the signature of another universe that exists in a different dimensional space where their matter is influencing ours via gravity. I know I have heard that gravity can leak from one brane to another, is this a possibility?

  19. #19 Doug Little
    August 19, 2011

    Mark in DC,

    Of course the atheist religious crowd resists that as logic is so often always an enemy of their blind and irrational faith

    There FIFY.

    Oh and Mark, you have no idea what Atheism is. It is you who are making the claim that an invisible sky fairy exists, the burden of proof is on you my friend. Atheists do not try and prove God’s don’t exist, that would be silly. It just so happens that everything we observe can be explained via natural processes, without the need to invoke some supernatural cause.

  20. #20 Ronald Blay
    August 19, 2011

    I am not an academic just a keen astronomer,I am sure that gravity is a forcecoming in from the stars that we have yet to discover when it passes through a body it weakens therefore where it emerges the incoming force is slightly stronger this keeps us on our planet surface.It would also explain why the universe is expanding as the stars are all pushing one another apart,the denser the body the weaker the outgoing force is, this is why a black hole devours everything,and scientists are still looking for dark matter.

  21. #21 Mu
    August 19, 2011

    I guess wrapping my head around the “dark matter can’t be baryonic” is my biggest issue. I know it contradicts our current models, but is there any observational evidence that excludes planetary size black holes etc from being the source of the extra observed gravity? To me, fixing the model seems the more obvious approach than postulating a new particle class with very unusual properties. As a side, is there a difference between a matter and an anti-matter black hole (aka would matter and antimatter still annihilate past the event horizon)?

  22. #22 Mark in DC
    August 19, 2011

    Thank you very much Doug for validating my argument. Your response was an emotionally-fused strawman, not based in reason and contained not a single logical refutation of any of my arguments nor made any serious attempt to substantiate your own.

    Par for the course for most atheists today…

    It is not I who is arguing that a Creator exists. It is science itself due to what we have empirically and forensically discovered about the universe. Being that it is both finite and temporal, ensures us, if you apply logic and reason, that nature had a beginning. And if nature had a beginning, only a fool would argue that the cause of nature is itself “via natural processes”.

    If you had ever been instructed in logic, you would have known that such a laughable argument violates the principle of contradiction, which is why I lament the loss of logic and philosophy as a requirement for those pursuing scientific degrees or any type of degree for that matter.

    Atheists spend their entire lives in denial of such scientific truths and then attempt to make scientific enquiries and promote sophistic archaic ‘theories’ that never consider what science has long since determined to be a causality certainty.

    The dogmatic atheistic faithful are very much like their progenitors who refused to consider sol-centricity and covered their eyes instead of looking through the telescope to see moons circling Jupiter.

    You can continue to keep your eyes closed all you like, but stop pretending that you are engaging in anything other than voodoo.

  23. #23 Lynxreign
    August 19, 2011

    @Mark in DC

    That’s a lot of words you used there to say exactly nothing.

  24. #24 Mark in DC
    August 19, 2011

    Lynxreign – I see I owe you my gratitude as well.

    It’s a wonderfully delicious sensation to have your arguments so quickly validated.

    I’m sorry that you have problems with ‘lots of words’. But maybe next time, out of a desire to appear rational or maybe a sense of personal shame, you would be so kind as to substantiate your own arguments and rely less on sophistic whines.

    I won’t hold my breath but I am eternally thankful that you interjected yourself in a manner that so thoroughly and delectably proved my point!

  25. #25 Ema Nymton
    August 19, 2011

    Wow.

    Mark in DC is a moron.

  26. #26 Ethan Siegel
    August 19, 2011

    A response to a selection of comments above:

    maxwell @7, assuming you’ve already worked through a basic year-long QFT course (through Peskin and Schroeder, or Bjorken and Drell if you’re older), you are likely ready for a field theory treatment of the axion and SUSY, which are canonical examples of the two leading classes of dark matter candidates: light non-thermal relics produced by phase transitions and heavy thermal relics from the very early Universe.

    I learned it from Pierre Ramond, and hence I can recommend this book — http://www.amazon.com/Journeys-Beyond-Standard-Frontiers-Physics/dp/0738201162 — as certainly being sufficient. I will give a plug that Ramond’s group theory book, if you ever have a proclivity towards that, is outstanding.

    Sascha @10, I particularly like the earlier of the two articles you linked to on your blog alpha_meme. People have an understandable distaste for propositions that are difficult to directly observe, but that is a problem with their preconceptions, not with the physics. People thought the neutrino was preposterous, and it took many decades to discover it directly, but it was in fact the best explanation by far for the observed phenomenon. Perhaps a better name could have been chosen for dark matter, but there are certainly fewer worse terms that could have been coined than dark energy, thankyouverymuch Mike Turner. You do well to encourage people to separate the two.

    psmith @11, light non-thermal relics, such as the axion, are one major class of candidates, and heavy thermal relics, such as the LSP, LKP, etc., are another major class. Either one could easily explain all the dark matter phenomena we observe today.

    Eric Lund @14, MoND was coined by Milgrom in his original paper: http://adsabs.harvard.edu/doi/10.1086/161130.

    mf @13, Mark @15, Troy @16, etc., you are free to believe what you want. If you take nothing else away from my post, I hope you take away that the study of the physical Universe on large scales — of all the different measurements and tests we make and perform — is important. It’s my scientific field, and it’s called Physical Cosmology. If you think that the Big Bang and Dark Matter can just be jettisoned for the reasons you gave that you find it distasteful, then you are in essence stating that Physical Cosmology isn’t really a science. That using the known laws of physics to describe the Universe on large scales and to explain the observables in our Universe using those laws is a bankrupt proposition, particularly if it leads you in a direction that you weren’t prepared to go in.

    And I am happy to provide you with a place to pontificate, but I have no sympathy for this viewpoint.

  27. #27 Terry Taerum
    August 19, 2011

    So I suppose my question would be, how much dark matter does a galaxy have? Does it have a peculiar distribution? Or is the amount “arbitrary” in the sense that we need to look at the shape of each galaxy and then deduce the amount? So, are there galaxies with virtually no dark matter (or dark energy for that matter). Or is dark matter a necessary and dominant constituent of each and every galaxy? Finally, how much dark matter exists between galaxies?

  28. #28 Raging Bee
    August 19, 2011

    Well, I see “Mark in DC” is pretending to be a good skeptical rationalist, and spewing anti-rational obscurantist bullshit…

    There is absolutely no SCIENTIFITC reason why ‘dark matter’ MUST BE or should be the most accepted model.

    Actually, the OP gave us plenty of good reasons for the (conditional) acceptance of dark matter. Denying such reasons, in a post where such reasons were clearly stated, is classic denialism.

    There is absolutely no empirical evidence that dark matter … exists.

    Again, read the OP: there is indeed empirical evidence that SOMETHING exists that we haven’t accounted for. And the OP freely admits that we’re still not sure what’s out there.

    And until that time there should be NO accepted model. PERIOD.

    So you’re saying we can’t be allowed to rely on a theory for as long as it seems to work? What’s your alternative approach — label it “unknowable” and stop trying to know it?

    Yes, ‘dark matter theory’ should be pursued and investigated and tested and whatever else is needed.

    That’s what scientists are doing. So what’s yoru problem?

    BUT until the theory is VALIDATED, there is no reason, unless one is a dogmatic atheist bent on proving there is no God, to teach or proclaim or demand that ‘dark matter theory’ be held in any higher esteem than any other theory that is credible and worthy of being validated.

    Why the sudden attack on atheists? You just let your bigoted religious agenda slip.

    Great advances in scientific thought are being stifled by the too numerous number of practitioners who have forced their dogmatic atheistic faith into the realm of scientific enquiry.

    Examples, please?

    And it would also be helpful if our universities started teaching students of science the meaning of ‘validity’ and the essential and necessary role that validity and logic play in all scientific enquiries.

    Care to specify which universities are failing to do so?

    Of course the atheist crowd resists that as logic is so often an enemy of their blind and irrational faith.

    Can you give us an example of even one prominent atheist doing this? Also, why do you hate “the atheist crowd” so much? And why is this hatred getting slipped into a discussion of physics? If you can’t keep your religious hatred out of a scientific debate, then maybe you should shut up and let wiser voices be heard.

  29. #29 Raging Bee
    August 19, 2011

    The biggest problem with dark matter/energy is that it’s just too convenient. Whatever gravitational effect you observe, we can create a distribution of matter/energy so that our current theories make correct predictions. At some point this seems like putting more and more gears on the celestial sphere.

    True. But that’s pretty much how most theories get their start: we assume a little something extra, and see if that makes for a better explanation/prediction of what we observe. Heliocentrism started that way too: the old explanation didn’t work, so some people assumed something completely different, then applied the assumption to see how well it explained what the old theory failed to explain. As long as scientists honestly admit that’s what they’re doing, everything should be fine. And so far, I see no evidence that anyone is doing otherwise.

    Dark matter — and its alteratives — look shaky right now because we’re just barely beginning to deal with what we observe. If one of them doesn’t get firmed up by further research, something else will.

  30. #30 Mark in DC
    August 19, 2011

    Dear Ethan,

    Thank you for your response. However you completely misstated my argument. I won’t assign motives but I would ask that you reconsider my argument and attempt a retort based upon the merit of my words, not a strawman that had nothing to do with my point.

    You wrote, “If you think that the Big Bang and Dark Matter can just be jettisoned for the reasons you gave that you find it distasteful, then you are in essence stating that Physical Cosmology isn’t really a science.”

    I implicitly stated that I do not want ‘dark matter theory’ to be jettisoned and in fact I outlined why it should continue to be researched and scientifically pursued. My mild critique related to your overall rationale and your understanding of the role of validity in determining scientific models.

    Besides that, I found your post well-written and illuminating, especially your critiques of other competing theories.

    To dear Ema Nymton. I am truly sorry that you were never made aware that the truest sign that one is a moron is when they are left with no option but to accuse that of others without even the slightest ability to substantiate it.

  31. #31 Ema Nymton
    August 19, 2011

    Odd. I’d say my assertion was quite amply substantiated in this thread.

    The problem, of course, is that morons–and Mark in DC is merely a convenient example–are used to not having the obvious truth pointed out as people bend over backwards to be polite.

  32. #32 OKThen
    August 19, 2011

    Ethan
    Your summary of the dark matter conundrum is quite good.
    Here are the problematic observations! (It’s a good list).
    Here is the one best simple hypothesis (i.e. dark matter) that solves the problems.
    Here are the best alternative hypotheses that have significant additional problems.
    Otherwise, they’d be the leading hypothesis.
    Nice. But yes, we can’t detect the stuff, a conundrum.

    My one question for today:
    Ethan says, “The fact that positrons (anti-electrons) have been observed experimentally to be attracted towards (and not away from) the center of the Earth.” Is there a solid reference??? Such would debunk one of my pet speculative ideas. Thanks.

    All I can find is references like, “The gravitational behavior of antimatter is still unknown. While we may be confident that antimatter is self-attractive, the interaction between matter and antimatter might be either attractive or repulsive.” http://arxiv.org/abs/1103.4937

    OK, so that’s my question for today.

    Yes, Ethan has finally convinced me that some kind of matter is the solution; so dark matter is a good name.

    Let me speculate a little:
    I am biased more towards antimatter than to MOND. I leave general relativists to build their case or not. I am biased that dark matter will be found to be a different phase of matter (e.g. in the sense that positron is a different phase of an electron) rather than entirely new particles. But experiments, observation will inform.

    I also speculate that particle accelerators may already have the data; we just may not have an adequate theory to sift it.

    OK, I’ve kept my personal speculation to a minimum.

  33. #33 NJ
    August 19, 2011

    MiDC@31:

    accuse that of others without even the slightest ability to substantiate it.

    Is there an IMAX in here? Because that’s a really big projection there…

  34. #34 Ethan Siegel
    August 19, 2011

    OKThen,

    I was always under the impression that the work of William Fairbank and his collaborators (such as Witteborn) demonstrated that positrons indeed fell in the presence of a gravitational field. For reasons unclear to me, it appears that many discount his work today as inconclusive, and so if that’s the case, perhaps I am the one who learns something today.

    Mark,

    The dark matter hypothesis — originally proposed in the 1930s — makes a large number of predictions about what should astrophysically be observed in various situations, many of which I outlined above. The anisotropies in the microwave background and the power spectrum of the large scale structure of the Universe are easily the two greatest technical successes of dark matter, and both of those were observed for the first time only relatively recently. The indirect evidence — as I am attempting (perhaps not as successfully as I’d like) to explain to you — is overwhelming. If you want to reject dark matter as the leading explanation, you must replace it with a better one.

  35. #35 Raging Bee
    August 19, 2011

    To dear Ema Nymton. I am truly sorry that you were never made aware that the truest sign that one is a moron is when they are left with no option but to accuse that of others without even the slightest ability to substantiate it.

    Coming from the guy who went out of his way to attack atheists, for no reason having anything to do with the original topic of this thread, the above sentence isn’t just incoherent; it’s hyporcitical.

    Also, Mark, you show your cowardice by responding to the name-calling, but not to any of the substantive points that I and others have made.

  36. #36 Mark in DC
    August 19, 2011

    >>>”Well, I see “Mark in DC” is pretending to be a good skeptical rationalist, and spewing anti-rational obscurantist bullshit…”

    Truth is often obscured by conventional thinking.

    >>>”There is absolutely no SCIENTIFITC reason why ‘dark matter’ MUST BE or should be the most accepted model.

    Actually, the OP gave us plenty of good reasons for the (conditional) acceptance of dark matter. Denying such reasons, in a post where such reasons were clearly stated, is classic denialism.”

    Conditional acceptance? LMAO and you think you are rational. How cute.

    So we should “conditionally accept” it for now, in our ignorance, until a day comes where we are less ignorant and are able and capable of proving it was a bunch of BS? Again LMAO.

    We should not accept it at all – we should merely consider it and continue to research, analyze and investigate it until we are able to determine if it is valid or if there are other more valid explanations. At this point in time we have no reason to assume it is valid any more so than we did to assume that the universe is contracting or slowing down. Yet how many years did the atheist crowd push that “conditionally accepted” BS down our throats?

    And arguing that it is valid SOLELY because it is slightly more valid than other less valid theories is not an argument you truly want to defend, is it?

    >>>”There is absolutely no empirical evidence that dark matter … exists.

    Again, read the OP: there is indeed empirical evidence that SOMETHING exists that we haven’t accounted for. And the OP freely admits that we’re still not sure what’s out there.”

    Something? LMAO Maybe that something is _____ (fill in the blank). I’m sorry but that you actually took the time to respond to me, yet filled your argument with such abject absurdities, which actually substantiate my original point, while claiming the high rational ground is beyond hilarious.

    I read the OP. The post confirmed that we have no empirical proof for ‘dark matter theory’. And then the OP went on to encourage us to treat ‘dark matter theory’ as if it “truly, most likely exists”.

    That you don’t understand the logical contradiction in such reasoning is funny indeed.

    >>> “And until that time there should be NO accepted model. PERIOD.

    So you’re saying we can’t be allowed to rely on a theory for as long as it seems to work?”

    It is unknowable right now – don’t you get it – that’s the whole point. Giving that ‘unknowable’ a label and calling it “the only acceptable model” is sophistry at its best.

    And yes, I am saying we CAN NOT rely upon ANY yet-to-be-validated theory until it is validated. We relied upon Ptolemy’s theory of geo-centricity for how many centuries? And you think that was wise simply because it was the seemingly most valid theory of its day? And you would have us continue such medieval practices?

    My approach is to continue to investigate this matter until we are able and capable of determining the answer. Not to fall back on assumptions and pretend that our assumptions are truths simply because other assumptions are weaker than ours. My approach is to keep an open mind but to also apply logic instead of searching for answers that fit some non-scientific preconceived dogmatic notion.

    >>>”Why the sudden attack on atheists? You just let your bigoted religious agenda slip.”

    Why do you ask questions that I’ve already answered? In fact why do you then post my answers below your question only to ask a different question?

    Atheism is an unscientific dogmatic paradigm that has been thoroughly discredited. To continue to allow atheistic dogma to influence scientific enquiry is not only irrational and extremely dangerous but promotes an anti-science climate that could eventually lead to another dark age.

    >>>”Great advances in scientific thought are being stifled by the too numerous number of practitioners who have forced their dogmatic atheistic faith into the realm of scientific enquiry.

    Examples, please?”

    I’ve listed a few already. Read the OP’s immediate dismissal of age theories. (“There are plenty of other observational tests that fail to line up, including the unacceptably short lifetime of the Universe”).
    Unacceptably short? Since science has no idea how old the age of the universe is and since science knows that the universe was created, then it makes no rational sense to discount such a theory. But the reason such theories are outright disregarded (and mocked) is because it contradicts the dogmatic beliefs of the atheist faithful.

    This same dogmatic mindset led most cosmologists to whole-heartedly believe that the universe was contracting. Yet we now know that it is expanding and exponentially. Do you know how long the astronomers who discovered that fact sat on that knowledge? And do you know why they sat on it? Because it conflicted with their preconceived atheistic notions.

    This is the same dogmatic mindset that led most scientists to believe that the radioactive rate of decay was a constant, which we just discovered is not.

    This is the same dogmatic mindset that leads most scientists to believe that the speed of light is a constant but now that theory appears to be falling apart as well.

    The destruction that the dogmatic atheist faithful have done to scientific advancements in the last 70 years is unfathomable. By refusing to consider all possibilities, because some theories contradict with atheism, is hardly the kind of mindset an objective and rational scientific person should have.

    Lastly, this attack on atheism is not a religious attack. You obviously don’t know the meaning of the word religion. My attack is purely scientific. And that’s what has your panties in a bushel.

    I hate atheism because it’s a lie that has been scientifically discredited. I hate atheism in the same way that I hate geo-centrism. And I feel towards atheists the way I would feel towards flat earthers.

    As for an example of such an atheist, I guess you are extremely ignorant, but maybe you’ve heard of Hawking? Maybe you caught how NBC pushed his anti-science screed last week on ALL of their cable networks at the same time? 10 different networks. It was truly mindboggling.

  37. #37 Mark in DC
    August 19, 2011

    Ethan,

    Now you are slightly changing your argument and I hope my posts had something to do with that!

    You wrote, “If you want to reject dark matter as the leading explanation, you must replace it with a better one.”

    I don’t. I also agree that it is the leading explanation at this time.

    However that is semantically different than arguing that “it really, truly, most likely exists”.

    Had your post merely been to show why dark matter is the ‘leading explanation’ of our day, I wouldn’t have bothered to comment. And, btw, you did a top notch job of showing why it is the leading argument. For that, bravo.

    I just believe that we should guard against allowing sophistry to influence this important debate.

    To Rage – cowardice? I do believe I did respond to every post that’s been made. Talk about projection. Not only did I respond and substantiate my arguments as well as my rebuttals, I noticed that you never came to my defense against the multitude who chose to ONLY make personal snide attacks against me. And the reason for why you chose to be a coward, is because you were afraid to go after your own. That is one further example of the dangerous climate that the atheist faithful have brought to modern scientific debates.

  38. #38 Raging Bee
    August 19, 2011

    My approach is to continue to investigate this matter until we are able and capable of determining the answer.

    This is exactly what scientists are doing WRT dark matter. And part of the ongoing investigation consists of taking the theories that have been offered so far, testing them by seeing how well they explain what we observe, and making judgements on which theories explain things best. That’s all anyone is doing with the dark-matter theory.

    Not to fall back on assumptions and pretend that our assumptions are truths simply because other assumptions are weaker than ours.

    Who here is doing that? Please give examples. I certainly didn’t see Ethan calling dark matter a “truth.”

    Atheism is an unscientific dogmatic paradigm that has been thoroughly discredited.

    Where has non-belief in a supreme being been “discredited?” Please give specific citations.

    Also, blaming the “dogmatic atheist mindset” for every instance where scientists have to change their theories is just plain bullshit — unless, of course, you can show that it was religion that forced every correction. Can you show that? Of course not — the scientists who question an established theory are no more and no less “atheist” than those who originally supported it. How do you know one bunch of scientists may have got something wrong? Because another bunch of scientists did actual science to call it into question.

    Lastly, this attack on atheism is not a religious attack. You obviously don’t know the meaning of the word religion. My attack is purely scientific.

    That’s what the cdesign proponentsists said.

    I hate atheism because it’s a lie that has been scientifically discredited.

    Scientists have proven the existence of a god? Please cite the references for that. In the meantime, thanks for admitting that your “purely scientific” screed is actually based on hate.

  39. #39 Steve
    August 19, 2011

    Ethan,

    The dark matter hypothesis does not make quantifiable predictions. There are some overall predictions, but nothing concrete that may be used to affirm or deny the theory.

    In fact, one of the most pronounced predictions from the dark matter hypothesis is that the universe should be closed or near closed. This was the main semi-quantitative prediction of the theory from some time. Once it became clear that the expansion of the universe was accelerating, the theory was modified to include repulsive dark energy.

    It seems to me that the biggest support for the dark matter/energy theory is that we have no better theory. That doesn’t seem like good science. A scientific theory of any merit should make quantifiable predictions that can be tested. Not just qualitative predictions that can be explained away if experiment does not match the predictions.

    In the case of antigravity, I can say that if we measure the gravitational force between particles and antiparticles, and that force is attractive, then the antigravity theory must be discarded.

    My question for you is this, Is there any experiment we could perform that would make you say that the dark matter/energy theory should be discarded?

  40. #40 Terry Taerum
    August 19, 2011

    Iam beginning to feel as if *I* am “dark matter”. Hello… is that an echo I hear? My question was, “So I suppose my question would be, how much dark matter does a galaxy have? Does it have a peculiar distribution? Or is the amount “arbitrary” in the sense that we need to look at the shape of each galaxy and then deduce the amount? So, are there galaxies with virtually no dark matter (or dark energy for that matter). Or is dark matter a necessary and dominant constituent of each and every galaxy? Finally, how much dark matter exists between galaxies?”

    Personally I don’t care if every galaxy is somehow different – that would be more intellectually comforting than the thought that intrically tied into matter is dark matter and it simply operates at a distance. I’m assuming that “dark matter” is somehow independent of that small percentage of the universe which is matter. So, as a neophyte (one of those dark matter bugs you squash because they’re inherently annoying) can my question be answered? Are there galaxies where (assuming dark matter exists) there might be large differences in the amount of dark matter? Which galaxies would those be?

    Thank you. :)

  41. #41 NJ
    August 19, 2011

    Dink @ 37:

    The destruction that the dogmatic atheist faithful have done to scientific advancements in the last 70 years is unfathomable.

    Specific examples please. Otherwise you are just making shit up.

    Lastly, this attack on atheism is not a religious attack. You I obviously don’t know the meaning of the word religion. My attack is purely scientific a function of my religious beliefs.

    FIFY

    This is the same dogmatic mindset that led most scientists to believe that the radioactive rate of decay was a constant, which we just discovered is not.

    {cite}

    This is the same dogmatic mindset that leads most scientists to believe that the speed of light is a constant but now that theory appears to be falling apart as well.

    {cite}

    It seems clear you are little but a YEC trying to play in the grown-ups game.

    Since science has no idea how old the age of the universe is and since science knows that the universe was created

    Actual science has a very good idea of how old the Universe is and no evidence supporting the idea that it was created. Your little YEC friends have been lying to you and you are too credulous to have found this out.

    I hate atheism in the same way that I hate geo-centrism.

    Your inability to differentiate between a philosophical position and a falsified hypothesis concerning physical reality verges on mental illness.

    Oops! You have let your rationality camouflage slip and exposed your true self. Happens every time. Now is the time for your condescending exit, executed clumsily for our amusement.

  42. #42 Omega Centauri
    August 19, 2011

    So, if dark matter and baryonic matter can be separated, by events such as galaxy cluster collisions, do we have some areas of the universe where the ration of DM to BM is dramtically different from what it is in our local universe? Would the morphology of galaxies, and gaxacie clusters differ substantially in these DM depleted or enhanced areas? Can we search for galaxy clusters with an unusual spectrum of galaxy morphologies.

    One DM theory, that seemed somewhat philosophically interesting, was the the wider universe cosnists of a large number of almost parallel branes. If nearby branes interact with our own only via gravity (and presumably ours with theirs), is it possible that DM, is simply the manifestation of Baryonic matter in nearby branes?

    So how cold is DM need to be? Obviously we have some clustering of it within galaxy clusters and galaxies. Assuming DM is some sort of elementary particle, isn’t some DM being lost by falling into black holes -or perhaps even getting trapped in stellar cores?

  43. #43 njd
    August 19, 2011

    Steve: I’m not Ethan, but if I’m understanding him correctly he’s already provided several experiments / observations that would lead to Dark Matter being discarded as a hypothesis. For example:

    (i) It could fail to predict the correct distribution of galaxies in space or in time: how they are grouped together, or how early or late after the Big Bang they formed. As I understand it, Dark Matter passes this test.

    (ii) It could fail to predict the rotation curves of galaxies, or the velocity distributions of galaxies in clusters. Once again, it passes this test.

    (iii) It could fail to predict the size and structure of the inhomogeneities in the cosmic microwave background. Test passed.

    (iv) It could predict incorrect values for ratios of primordial isotopes. Test passed.

    (v) Gravitational lensing of light by the dark matter in a galaxy or cluster could consistently fail to be observed. Test passed.

    If you want tests that have yet to be carried out that could disprove dark matter, I’ll have to use more imagination. What about:

    (a) Discovery that MOND is correct. Dark matter plus MOND would surely give incorrect rotation curves for galaxies.

    (b) Discovery of lots of extra baryonic matter – jupiters or smallish black holes, for example. With lots of extra baryonic matter there mightn’t be room for dark matter any more.

    (c) A significant change in current models of galaxy formation, such that the nature and quantity of dark matter required to reproduce what we see in the sky no longer matches the requirements of the other observations that dark matter currently explains.

    (d) Observations of galaxies with anomalous rotation curves or clusters with galaxies moving too fast that don’t show the gravitational lensing that the extra mass of dark matter would require them to show.

    (e) More precise measurements of isotope ratios or the fluctuations in the CMB that fail to match the predictions of dark matter.

    While it’s true that no experiment is ever going to prove that no dark matter whatsoever exists, it is relatively straightforward to test whether its presence in significant quantities is consistent with what we observe in the sky. Dark matter has significant effects on many phenomena, and so it is an idea that can be tested in many different ways. Doing this involves both theory and observation, and as such seems to me no less scientific than any other branch of cosmology, or indeed of science.

    (Disclaimer: I am not a real physicist!)

  44. #44 Ema Nymton
    August 19, 2011

    So would that qualify as extra evidence?

  45. #45 Mark in DC
    August 19, 2011

    To NJ,

    Dink, eh? Thanks for joining the crowd and you fit right in. So scared by other’s beliefs that you have to go personal, huh? That right there is a specific example and all the proof anyone should need that atheists have destroyed objective scientific enquiry. You are literally afraid of some answers – so frightened in fact that you lash out with personal slanders and sophistic strawmen.

    That you don’t even realize it is either beyond hilarious or utterly sad. Probably a bit of both. You and your ilk are essentially pharisaic high priests. No wonder they murdered Christ, lol. (Boy a joke like that is sure to bring out only the best in the atheist faithful – I am dying with anticipation now, lmao).

    So now you need me to cite my claims because apparently you haven’t stayed up to date on the latest scientific discoveries. Big shock there.

    Radioactive decay rates: http://news.stanford.edu/news/2010/august/sun-082310.html

    Possibility speed of light is not a constant: http://www.sciencedaily.com/releases/1999/10/991005114024.htm

    BTW, I am not a young earth creationist. I have no idea how old the universe is – no one does. We can hypothesize but until someone creates a time machine and goes back and actually observes the origins, then it will ALWAYS be empirically impossible to formulate a timeline. That you are unaware of this is just another disastrous and specific example of the destruction that atheism has wrought on higher education, especially in the scientific fields.

    Had you been properly taught the role of logic and validity, you would have not so pettily embarrassed yourself by exposing your ignorance on these points.

    But like I said, this is not a matter of science for you or any who have lashed out at me today – it’s a matter of defending your dogmatic atheist faith.

    That logic so clearly proves the existence of the Creator, when analyzing the cosmological evidence, such as the finite and temporal nature of nature, is why you and your crowd must diminish the role of logic in both education and in the field of science itself.

    Unlike you, I leave open the possibility that the universe is young – much younger than conventionally thought. Do you? Of course not. You are a closed minded dogmatist. Thus you prohibit yourself from even considering certain scientific theories, completely out of fear, because of the chance they may lead you to rejecting your faith.

    No evidence that nature has been created, you say? I think you need to scream it and repeat it ritualistically until no dissent can be found!

    Unfortunately for atheists like you, though, the evidence is abundant and has been validated. Nature is finite – an infinite object cannot expand. Nature is temporal. The laws of thermodynamics makes that extremely clear. As I posted above, being that it is both finite and temporal, ensures us, if you apply logic and reason, that nature had a beginning. And if nature had a beginning, only a fool would argue that the cause of nature is itself “via natural processes”.

    We humans are ignorant about many things but a few things science that has made abundantly clear is that the Cause of nature cannot be natural and the Cause of nature cannot be temporal and the Cause of nature cannot be finite.
    Thus, we scientifically know that nature was caused by a supernatural (or extra-natural), eternal and infinite source. And as long as we humans continue to maintain that nature is finite and temporal then you have no choice but to accept that our nature was created, if you desire to be scientifically objective.

    Though I highly doubt you have ever had any such desires.

  46. #46 Mike
    August 19, 2011

    Good post, wonderful pictures. I was especially interested in the evidence from the bullet cluster. It’s rather convincing.

  47. #47 forrest noble
    August 19, 2011

    As always Ethan offers a lot of cool info, graphics, and up-to-date mainstream thought. As for me, I think this analysis is particularly interesting because it discusses problems with aspects of the mainstream model, offering dark matter as a general solution for those problems mentioned.

    Aether theory of the 19th century proposed that there was a background particulate field of some kind whereby they brought back the old word aether to explain it. Later toward the latter part of the century they better understood the wave theory of light and it was proposed that this aether that seemed to explain the double slit and other wave experiments, could also be the carrier of light. At the end of the 19th century Michelson and Morley and others seemingly could not find the aether so the idea was discarded.

    Here we are more than a hundred years later, realizing that there must still be a background field of some kind, by which many present problems concerning observation can be explained. The particles proposed have been dark matter of many different varieties, Higg’s particles, gravitons, quantum sand, quantum foam, field strings, etc. etc. etc. This particulate field could again be called an aether, or we can give another name to it this time. Once we find it we might again realize that it also could be the “carrier” of EM radiation, as well as De Broglie waves.

    Since some time and effort has been put into finding dark matter, some things about the idea of it never seem to be discussed. For instance if one throws a lot of dark matter into and surrounding a spiral galaxy, the outer galactic stars will not necessarily orbit faster. Dark matter could stop the galaxy rotation all together, it just depends upon the momentum of the dark matter relative to the galaxy. The question is what perpetuates its motion? So here I believe we are talking about some varying densities and funneling/ vortex currents like the aether models of yore proposed.

    Next we assume that GR is the correct model of gravity, which may be a mistake. GR proposes that matter warps space but observations to date seem to indicate that the observable universe is Euclidean. Instead if we consider an aether model of gravity, we would have a type of dark matter of some kind built into the model of gravity.

    Background field particles/ strings do not have to have mass if they are the reason for gravity. Photons are believed to have no mass, yet their momentum can drive/ accelerate a solar sailed craft far out into the solar system. If an aether is the source of gravity then matter would sink under the influence of gravity, but the aether background itself might be thought of as an omnipresent atmosphere that does not sink under the influence of gravity, instead it would be the cause of gravity. Such an background aether omni-present “atmosphere” could also saturate the quantum would as well as the macro-world. Evidence for this background field would seemingly be the ZPF.

    Since this thread is about dark matter, lets say that the background ZPF is full of dark matter. As Ethan pointed out, best-fit dark matter would seemingly be neutral in charge, but it does not have to be neutrinos since other theoretical problems seem to arise. If these particulates are the cause of gravity they do not have to have mass to them either. They also do not have to be matter, as in “dark matter.” They could have substance to them like photons, be neutral in charge, but no mass/ matter would be needed. They could be very small so that individually they could not be observed.

    My estimate as to their size is about 10^30 m. or smaller, as a particle, string, string of minuscule particles, etc.

  48. #48 Alan L.
    August 19, 2011

    @Eric Lund #14

    —I’m not familiar with MOND theories, so I don’t know what free parameters there are in the model or how sensitive the model is to adjusting those parameters. But it’s a safe bet that the curve Ethan shows is based on some “best fit” of those parameters to some data set. Yes, MOND does that well.—

    I’d just like to mention that I tried very hard to phrase my question in post #8 in a manner so narrow that it would provide an absolute minimum amount of wiggle room for anyone to provide an answer to a question I did not ask.

  49. #49 Tristan
    August 19, 2011

    Every time I try to think about the challenges involved in solving the n-body problem on the cosmological scale, my head starts to hurt. I keep getting hung up on the speed of light (or, in this case, the speed of gravity).

    Take the case of a spiral galaxy 100,000 light years across. Therefore a star at the outer periphery is ~ 50,000 light years from the central mass. Hence, the force it experiences at any one time comes not from where that mass is at that time, but from where it was 50,000 years ago. Now generalize that to every interaction between every point mass…

    How does one handle that? Keep a running buffer of previous frames, and work out the force vectors based on those? How do you initialize such a simulation? So many questions…

    Consider another scenario: a series of equal masses, equally spaced around a circular orbit. If they were at rest, each would feel an attractive force from the one ahead, and an equal force from the one behind. But, set them moving and take signal delay into account, and this must surely change. The force each mass will feel in this case comes from a time when the mass ahead was slightly closer, while the mass behind was slightly further away. This should lead to a small but non-zero net force accelerating all the masses forwards.

    This feels to me like it violates conservation of energy, but I can’t see where I’ve gone wrong. Any help?

  50. #50 JimV
    August 19, 2011

    For the benefit of lurkers, rather than Mark in DC, who will ignore it since he could have easily googled it himself, if he were interested in looking at all sides of an issue:

    RE: variation in the speed of light in a vacuum over time –

    See http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/constants.html

    “… Over the past few decades, there have been extensive searches for evidence of variation of fundamental “constants.” Among the methods used have been astrophysical observations of the spectra of distant stars, searches for variations of planetary radii and moments of inertia, investigations of orbital evolution, searches for anomalous luminosities of faint stars, studies of abundance ratios of radioactive nuclides, and (for current variations) direct laboratory measurements.

    One powerful approach has been to study the “Oklo Phenomenon,” a uranium deposit in Gabon that became a natural nuclear reactor about 1.8 billion years ago; the isotopic composition of fission products has permitted a detailed investigation of possible changes in nuclear interactions. Another has been to examine ratios of spectral lines of distant quasars coming from different types of atomic transitions (resonant, fine structure, and hyperfine). The resulting frequencies have different dependences on the electron charge and mass, the speed of light, and Planck’s constant, and can be used to compare these parameters to their present values on Earth. Solar eclipses provide another sensitive test of variations of the gravitational constant. If G had varied, the eclipse track would have been different from the one we calculate today, so the mere fact that a total eclipse occurred at a particular location provides a powerful constraint, even if the date is poorly known.

    So far, these investigations have found no evidence of variation of fundamental “constants.” The current observational limits for most constants are on the order of one part in 1010 to one part in 1011 per year. So to the best of our current ability to observe, the fundamental constants really are constant.”

    RE: variation in decay rates of radioactive elements –

    From Wikipedia:

    “… Comparison of laboratory experiments over the last century, studies of the Oklo natural nuclear reactor [mentioned above--JV] (which exemplified the effects of thermal neutrons on nuclear decay), and astrophysical observations of the luminosity decays of distant supernovae (which occurred far away so the light has taken a great deal of time to reach us), for example, strongly indicate that decay rates have been constant (at least to within the limitations of small experimental errors) as a function of time as well.

    Recent results suggest the possibility that decay rates might have a weak dependence (0.5% or less) on environmental factors. It has been suggested that measurements of decay rates of silicon-32, manganese-54, and radium-226 exhibit small seasonal variations (of the order of 0.1%), proposed to be related to either solar flare activity or distance from the sun.[6][7][8] However, such measurements are highly susceptible to systematic errors, and a subsequent paper[9] has found no evidence for such correlations in six other isotopes, and sets upper limits on the size of any such effects.”

  51. #51 NJ
    August 19, 2011

    Dink @ 46:

    Dink, eh? Thanks for joining the crowd and you fit right in. So scared by other’s beliefs that you have to go personal, huh?

    You like that? The tactic is most useful for getting creationists and their ilk and kith and kin to come out from their oh-so-reasonable facade and show their true colors. You struck that fly like a hungry bass, son.

    As for the fear, that’s just you projecting again. You are terrified that your preferred interpretation of your preferred translation of your preferred ancient religious writings won’t stand up to careful scrutiny. So you try (not competently, as you don’t have the skills) to attack the methodological naturalism that underpins the science.

    Fortunately, science is much stronger than you.

    So now you need me to cite my claims because apparently you haven’t stayed up to date on the latest scientific discoveries. Big shock there.

    Being an actual scientist, I was in fact aware of them. A lone physicist proposes several radical changes to our understanding of light, gravity and quantum field theory, but with no particular experimental backing. The details are out of my field, but suffice to say that his proposals are a long way from saying the idea of c invariance “appears to be falling apart”.

    As for the radioactive decay (closer to my field), the Stanford researchers are hypothesizing that tiny variations may be correlated with solar events, suggesting an interaction between neutrinos (or an unknown agent) may affect certain isotopes.

    What is being discussed is an externally accelerated breakdown. You could demonstrate this yourself! Hold a 5 kilo mass of Pu in one hand and another 5 kilo mass in the other hand and bring your hands together.

    Do not try this anywhere near me.

    I’m not aware so far that anyone else has replicated their effect, but more importantly, even if it holds, the difference is miniscule and not the several order of magnitude change you need to have a young Earth and Universe.

    See, this is what happens when you copy and paste from a Website without understanding. You make laughable mistakes.

    BTW, I am not a young earth creationist. I have no idea how old the universe is – no one does. We can hypothesize but until someone creates a time machine and goes back and actually observes the origins, then it will ALWAYS be empirically impossible to formulate a timeline.

    Oh, I can just hear you {Australian accent} Were you there?{/Australian accent}. The only way to know what happened in the past would be to have been there. Sorry, sonny, in the real world we use evidence to piece together the story of the past, even if we don’t have every detail. Just because I don’t know what Julius Caesar had for breakfast the morning before he crossed the Rubicon doesn’t mean no one knows anything about ancient Rome.

    BTW, the only people who claim agnosticism on the age of the Earth/Universe are YEC’s in disguise. This just demonstrates that you are trolling dishonestly. Quel surprise!

    But like I said, this is not a matter of science for you or any who have lashed out at me today – it’s a matter of defending your dogmatic atheist faith.

    Please quote exactly where I claimed to be an atheist.

    {crickets}

    Your terror has crept in again. Someone challenges your statements and you project the antithesis of your religious beliefs. It clear one of us doesn’t have a lot of skills at logic; if you want to have a look, go find a mirror.

    it’s a matter of defending your dogmatic atheist faith

    See above. That you assign atheism as a ‘faith’ rather than a mere lack thereof illustrates again that you are just projecting your beliefs with an opposite sign.

    If atheism is a faith, does that mean that not collecting stamps is a hobby?

    That logic so clearly proves the existence of the Creator, when analyzing the cosmological evidence, such as the finite and temporal nature of nature, is why you and your crowd must diminish the role of logic in both education and in the field of science itself.

    Circular reasoning – see Reasoning, circular.

    You presuppose your preferred set of beliefs, so it is unsurprising you end up with them at the end.

    You are I am a closed minded dogmatist. Thus you I prohibit yourself myself from even considering certain scientific theories, completely out of fear, because of the chance they may lead you me to rejecting your my faith.

    FIFY. You do love you some projection don’t you?

    Unfortunately for atheists like you, though, the evidence is abundant and has been validated. Nature is finite – an infinite object cannot expand. Nature is temporal. The laws of thermodynamics makes that extremely clear. As I posted above, being that it is both finite and temporal, ensures us, if you apply logic and reason, that nature had a beginning. And if nature had a beginning, only a fool would argue that the cause of nature is itself “via natural processes”.

    We humans are ignorant about many things but a few things science that has made abundantly clear is that the Cause of nature cannot be natural and the Cause of nature cannot be temporal and the Cause of nature cannot be finite.
    Thus, we scientifically know that nature was caused by a supernatural (or extra-natural), eternal and infinite source. And as long as we humans continue to maintain that nature is finite and temporal then you have no choice but to accept that our nature was created, if you desire to be scientifically objective.

    More presuppositionalism. Classic creationist logic failure, since once you assume something it remains embedded in your conclusions.

    Well, this has been fun. Outing a camouflaged creationist is always good sport. And consider that your intellectual failure is now an open target for all to see.

  52. #52 Raging Bee
    August 19, 2011

    I have no idea how old the universe is – no one does. We can hypothesize but until someone creates a time machine and goes back and actually observes the origins, then it will ALWAYS be empirically impossible to formulate a timeline.

    You could make that bogus argument about ANY event we didn’t witness first-hand — including just about every homicide ever committed. Why don’t you hire yourself out as an “expert witness” so defense attorneys can pretend that no one can ever be proven guilty of any crime without a time machine?

    Seriously, that argument is classic know-nothingism. It’s an argument from pure willful ignorance, with the obvious intent of stopping science from doing anything.

    We humans are ignorant about many things but a few things science that has made abundantly clear is that the Cause of nature cannot be natural and the Cause of nature cannot be temporal and the Cause of nature cannot be finite.
    Thus, we scientifically know that nature was caused by a supernatural (or extra-natural), eternal and infinite source.

    Citations please? What scientific work, exactly, has made this “abundantly clear?”

    Unfortunately for atheists like you…

    How do you know anyone here is an atheist? I’m not.

  53. #53 Steve
    August 19, 2011

    njd @44

    The problem of the tests you propose is that they are all self-fulfilling. In each of the tests your propose, the dark matter/energy *assumption* is that the distribution of dark matter/energy is precisely what is required for experiment to match theory.

    This is the fundamental problem. We simply *assume* that the distribution is exactly what is required. The hypothesis does not pass any of these tests, because the hypothesis does not make any quantifiable prediction. The only way we get a quantifiable prediction is to look at a physical situation, measure what happens experimentally, compare this with what the theory predicts should happen given the observed matter, then we *assume* that any discrepancy between is the result of the dark matter distribution, and reverse calculate the distribution of dark matter.

    The problem is that the hypothesis cannot be falsified. If theory matches experiment, we determine the dark matter/energy density must be locally zero (or negligible). When we observe high divergence between theory and experiment, we simply assume that the dark matter/energy must be locally dense. If we need more gravity, we just add a dash of dark matter. If we need less gravity, we add a dash of dark energy.

    Don’t misunderstand, I agree that this is the leading theory, and for good reason. However, at this point it would be very presumptive to stop investigating alternative theories. If we can identify dark matter/energy, measure the particle properties, or at least make an independent measurement, that would be a significant advance.

    However, we should construct experiments capable of disproving the hypothesis. So, is there any experimental test that would definitely rule out dark matter/energy?

  54. #54 forrest noble
    August 20, 2011

    Steve,

    “…is there any experimental test that would definitely rule out dark matter/energy?”

    As you suggest, neither are quantifiable concerning predictive capability. The proper word is “retrodiction.” Proving they don’t exist seemingly is like proving that the spiritual world does not exist, considering there are many testimonials that it does exist.

    If theory changes, the most likely reason will be to show evidence that another possibility is more likely :)

  55. #55 Steve
    August 20, 2011

    forrest,

    I have to disagree with you here. This is the difference between science and faith.

    You suggest that experiment needs to prove that no dark matter/energy exists. This is the wrong idea. We don’t assume theories are correct until proven wrong. Theories need to make predictions that allow them to be confirmed or denied.

    Where is this test for dark matter/energy? Is there any example of a quantitative prediction made by the theory prior to experimental evidence? A number or range that we can test with experiment to show that experimental observations confirm the value, or alternatively, if experimental values differ, we would agree that the theory is incorrect?

    Comparing with related theories:

    Newton’s gravitation made firm predictions about the relationship between the mass of the Sun, the distance between the planet’s and the sun, and the period of a planet’s orbit. These could be measured experimentally. If theory did not match experiment, Newton’s gravity would have been discarded.

    Einstein’s General Relativity made specific predictions about the perihelion shift in Mercury, bending of light around the sun, and shifts in spectral lines. If any of these quantifiable predictions had proved false, General Relativity would have been discarded.

    Quantum Electrodynamics made specific predictions about the value of the anomalous magnetic moment of the electron. This has been confirmed by experiment.

    As to unproven theories:

    Antigravity predicts that the force between particles and antiparticles should have the same magnitude but repulsive instead of attractive.

    The Standard Model predicts the Higgs particle must have a mass less than 200 GeV. The LHC is currently measuring the last portion of this range. If no Higgs is detected, the Standard Model is wrong.

    All of these theories make specific, quantitative predictions that can be verified by experiment. These predictions are made *before* the experiments are conducted. The experiments confirm or reject the theory.

    Why is dark matter/energy the exception?

  56. #56 OKThen
    August 20, 2011

    Ethan
    Thanks, I’ll check out the William Fairbank and his collaborators (such as Witteborn) work; even if it isn’t definitive.

    It would be nice to have a decisive experiment though.

    And thanks, I am convinced that the indirect evidence is quite substantial; so I would be quite surprised if no particle of some time is found to be responsible for the dark matter observations.

  57. #57 OKThen
    August 20, 2011

    Ethan
    “William Fairbank attempted a laboratory experiment to directly measure the gravitational acceleration of both electrons and positrons. However, their charge-to-mass ratio is so large that electromagnetic effects overwhelmed the experiment.” Wiki. Other sources seem to agree that no experiments have settled the matter. It would be nice to have such experiments, which are very difficult.

    My personal speculation is that gravitationally masses ++ attracts, — repells, +- and -+ are neutral all in a time forward sense of our visible universe. I think CPT parity violations and conservation of energy can be accomodated in this gravitational scenario which is totally different than the electromagnetic scenario. NOTE THIS IS PERSONAL SPECULATION, i.e. BUNK UNTIL PROVEN OTHERWISE.

    For all of you speculative types, every crazy idea that you or I think up; just means that we are thinking. Which is good.

    But if we are honest, we recognize that the real detailed vetted science is very difficult. Consider William Fairbank’s idea for an experiment: for at least the last 50 years physicists have wanted to do his experiment; but it has been too difficult, errors creep in. Nevertheless, we need to try to frame our crazy ideas in testable terms. And if you are like me, many of my crazy idea have already been tested. Thus slowly as I learn, I discover that 2/3 of my ideas are already proven to be bogus. That’s OK; I’ve learned. I also slowly learn than 1/3 of my ideas are correct or at least not ruled out yet (even if my reasoning was not so correct). But learning for an individual or a scientific community involves a lot of failures. The scientific process, the learning process is messy. But to learn we must fail; think of Edison’s 10,000 tests until his team found a suitable filament for the light bulb.

    To learn is to make mistakes. What Edison taught us was to accellerate learning we must increase our number of mistakes. i.e. run 100 experiments at a time not 1 or 10. This is the real crime (the lack of vision) of not funding scientific research. We don’t have the chance to seriously fail enough and hence to accelerate our learning about nature.

  58. #58 njd
    August 20, 2011

    Steve at no. 54: thank you for your reply! I think I have to disagree with you about the examples that I gave all being “self-fulfilling”. Let me explain what I mean.

    First, the primordial isotope ratios and the inhomogeneities in the CMB date from events taking place at very early times, when the density of matter (dark or otherwise) was essentially uniform across the Universe. If the isotope ratios required a ratio of 6:1 (dark:baryonic) to match theory and observation while the CMB required a ratio of 10:1, the dark matter hypothesis would have serious problems.

    The galaxy formation calculations relate to later times, when matter was no longer distributed evenly. The extent to which there is “wiggle room” in these calculations is unclear to me, and you had better get your answer from someone who knows more. However, I don’t think that the wiggle room is unlimited: simulations of galaxy formation do rule out hot dark matter (e.g., neutrinos), I believe, and they do apparently rule out having no dark matter, so I would think that there is once again a chance to disprove the dark matter hypothesis. If the 6:1 ratio coming from the CMB observations cannot lead to the correct distribution of galaxies, then there’s a problem.

    At the level of individual clusters or galaxies I imagine (though I do not know) that a far greater range of dark matter densities is to be expected. I fully take your point that, for example, calculating the density of dark matter in a galaxy to make its rotation curve fit does not provide any direct evidence that dark matter actually exists. But if one measures the galaxy’s mass in some other way – perhaps through the gravitational lensing it produces, or through its gravitational effect on other galaxies in its cluster – the actual presence of the dark matter in the required amount becomes disprovable. If there really is no “dark” contribution to the galaxy’s mass, this should show up when the mass is measured directly.

    So I’m afraid I can’t agree that the dark matter hypothesis cannot be falsified.

    Finally, I completely agree that alternatives should be investigated. Is anyone suggesting that this should not happen? That certainly isn’t how I read Ethan’s article!

  59. #59 Owlmirror
    August 20, 2011

    O wise NJ, O Raging Bee,
    Don’t you see? Don’t you see?
    Little Mikey in DC
    Is not like you, and not like me.

    Little Mikey knows what’s TRVE
    And he’ll tell it to me and you.
    Even though ‘twould be fallacy
    If said by you or said by me.

    If we commit equivocation,
    it would cause great consternation.
    But Little Mikey’s no mere numpty
    He’s the one true Humpty-Dumpty!

    If we commit some special pleading,
    we might well be accused of cheating.
    But Little Mikey in DC
    Is just special — and pleading’s free.

    If our conclusions we assume,
    our logic tumbles to its doom.
    But Little Mikey doesn’t care —
    his bare assertions float on air!

    If our logic does not follow,
    our arguments will sound all hollow —
    But not for Mikey in DC
    Logic’s what he says, you see?

    Little Mikey in DC,
    He’s not like you and not like me.
    Though you or I might think it odd,
    Little Mikey thinks he’s GOD.

  60. #60 Owlmirror
    August 20, 2011

    A lone physicist proposes several radical changes to our understanding of light, gravity and quantum field theory, but with no particular experimental backing. The details are out of my field, but suffice to say that his proposals are a long way from saying the idea of c invariance “appears to be falling apart”.

    Well, Moffat isn’t the only one positing varying speed of light scenarios; there are a few others.

    But it’s worth emphasizing that these cosmological VSL conjectures are meant to modify/replace the inflationary period of the big bang — instead of the universe rapidly changing in size, the speed of light (and in some scenarion, gravitation) was much higher so as to allow for the same effects seen in the CMBR. And of course, the inflationary period was a very small fraction of a second (10^−36 seconds to sometime between 10^−33 and 10^−32).

    So these cosmologists — who are basing their work on the same results that give an age of the universe of about 13.7 billion years, which they do not dispute — are positing that perhaps, for a tiny tiny fraction of a second, the speed of light was higher at the very beginning of the Big Bang from what it is now.

    And of course, they would all agree that the speed of light has been constant since then.

    Or so I understand of them, anyway.

  61. #61 forrest noble
    August 20, 2011

    @Steve, posting #56

    I think we are on the same page here. What I said was “neither (dark matter nor dark energy) are quantifiable concerning predictive capability.” Both use retrodiction to claim validity. I didn’t say we need to prove anything; what I said was: that one can’t prove they don’t exist any more than one can disprove the spiritual world.

    “…..predictions are (should be) made *before* the experiments are conducted. The experiments confirm or reject the theory.”
    (parenthesis added)

    “Where is this test for dark matter/energy? Is there any example of a quantitative prediction made by the theory prior to experimental evidence?”

    None that I know of.

    “Theories need to make predictions that allow them to be confirmed or denied.”
    I totally agree and do not foresee any testable predictions for either, based upon my readings. If there is such a prediction that could provide evidence for or against these hypothesis if discovered, then all they need to do is throw in a little related unique theoretical physics and then they could call them both theories. If they are not disprovable, and if they make no new predictions, they must remain ad hoc hypothesis.

    “Why is dark matter/energy the exception?”

    I ask the same question. I think The same inability to make new predictions should be an indicator of future problems with a model. I think the same criticism also applies to the Inflation hypothesis as well as the Big Bang model itself. I also see nothing new on the horizon concerning present or new predictions for either :( Do you know of any? I researched it on Google and found nothing concerning new predictions of the Big Bang model.

    The problem, I think, is that when there is just one preferred model, everybody is working on it. Concerning the Big Bang model, there are thousands of researches. Two or three researchers write a paper predicting one thing, two or three others predict something else, and so on. No matter what is discovered a claim can be made that it was predicted by the model.

  62. #62 NJ
    August 20, 2011

    Owlmirror@60:

    Pretty good, but I don’t think I can dance to it. I’d rate it about 850 milli-cuttlefish

    Owlmirror@61:

    Interesting, and like I said not my field. Do the other VSL conjectures necessarily need to modify gravity and QFT for the same results?

    In any event, it was abundantly clear our departed creationist chew toy was just copy pasta-ing what somebody told him to think and didn’t bother to follow up.

  63. #63 forrest noble
    August 21, 2011

    @njd posting #44,

    The examples given: i thru v, and a thru e, are justifications for why they believe dark matter is a valid theory. Although interesting, the problem is that they can make no predictions with the model.

    I think a prime example concerns two spiral galaxies that appear to be generally the same based upon their visual appearance – redshift, form, color, size, number of aged stars, young stars, density or stars, etc. Upon a long study concerning redshift differentials and other clues they finally realize that one galaxy is rotating twice as fast as the other concerning its stellar rotation rate relative to the background field, and also that its relative stellar velocities within the galaxy are quite different from one to the other. No gravitational formula, Newtonian, GR, MOND, etc. could predict the stellar velocities of either galaxy based upon their appearances since they appear the same. Once that observation can enable the estimation of stellar velocities, then the right amount of dark matter with the right velocities, can be thrown into the mix and then retrodict rotation velocities. This is how hypothesis work, not quantitative predictions of theories. Yes if you throw in the right amount of dark matter here and there it can match observation. But why add more to one galaxy than another, or to one cluster more than another when they appear the same.

    One could always speculate as to why distributions of dark matter might be different, but this is not mentioned in the normal discussions of dark matter since if they are gravitationally influenced, in time they should gravitate to the center of the galaxy.

    I also think there is something there, only the effects of which we can visually observe, hence “dark matter.” I don’t, however, believe this hypothesis is advanced enough to justify calling it matter yet, as others have pointed out in this thread.

    My expectation is that at long last we are finally observing the effects of a particulate aether on the macro-scale, not just in the ZPF at the quantum level. And that dark matter is just the present name given to it.

  64. #64 desheuer
    August 21, 2011

    @steve, ethan
    Concerning matter/antimatter, GR and CPT:
    please check AeGIS experiment at CERN
    and
    M. Vilatta – CPT symmetry and antimatter gravity in general relativity

  65. #65 dmholland
    August 21, 2011

    OKthen @ 58 said:

    My personal speculation is that gravitationally masses ++ attracts, — repells, +- and -+ are neutral all in a time forward sense of our visible universe.

    How do photons fit into this senario?

  66. #66 Owlmirror
    August 21, 2011

    Do the other VSL conjectures necessarily need to modify gravity and QFT for the same results?

    I don’t have the expertise to evaluate them, really. I was mostly going by my memory of Magueijo’s popular book on his speculation.

    Here’s his more technical review of various VSL ideas, FWIW: New varying speed of light theories.

    In any event, it was abundantly clear our departed creationist chew toy was just copy pasta-ing what somebody told him to think and didn’t bother to follow up.

    It was the link to the 1999 sciencedaily press release, rather than anything more recent or substantive, which made me suspicious — that’s what I’ve seen creationists link to before.

  67. #67 OKThen
    August 22, 2011

    @65 dmholland
    My point is not to argue for my personal speculations. My point is that that personal speculation is falsifiable. And I’d like to know even if I am completely wrong. But seems that I still have to wait.

    But what exactly is your question about photons?

    I am an outsider who respects experiment, observation and theory. But if critical experiments and observations have not been made; then I can question current best theory outside the limits of experiment observation.

    But I own it to myself to continually question and try to break my own speculative ideas. Being an outsider with my head in the sand is to be a fool. I must keep my mind open, try to understand current best theory and experiment more deeply, study and learn; else I have no integrity. Scientific integrity is not just for the professional scientist; if we are to be scientifically literate then scientific integrity must be our responsibility too.

    On this blog, I ask questions to clarify my understanding. Personally thinking, hypothesizing and engaging science with my questions; is not something I can delegate.

    Now on this dark matter topic. I don’t like the idea of dark matter. It means 83% of the matter in the universe is missing; this is a scientific embarassment. And giving it a name “dark matter” doesn’t make it any less embarassing. But I look at Ethan’s list of evidence suggesting indirectly that there is something that we can call dark matter. And I find that I have run out of skepticism.

    Now within the world of physics ideas there are many possible very strange particle somethings that can be candidate ideas for this dark matter. So far, none have been found; so you, I and the best theoretical physicists in the world are entitled to our personal and professional but fuzzy reasoned biases.

    I say fuzzy reasoned because clear ideas often emerge from the fringe, the fuzz. Personally, I think that when we finally understand “dark matter”; we will also have a much better understanding of the missing antimatter in our visible universe, quantum gravity, extra dimensions and time. In a nutshell, understanding “dark matter” seems to be at the heart of some very important new physics.

  68. #68 Antoni Jaume
    August 22, 2011

    What would happen if forces were quantized?

  69. #69 SCHWAR_A
    August 24, 2011

    @OKThen (69)

    …understanding “dark matter” seems to be at the heart of some very important new physics.

    I totally agree with you!

    Must there be an alternative to “Dark Matter”? Let us understand “Dark Matter” as the working-name for phenomena found and not yet explained. And when we can explain them, then we can, and I think we will rename this working-name.

    For me it helps not to see the word “Matter” literally – I see this word as something, which behaves somehow like “Matter”…
    Thus I do not look for particles, but for concepts leading to this “additional” behaviour of the actual (baryonic) matter.

  70. #70 Lesley
    August 25, 2011

    Only if the heavens above can be measured and the foundations of the earth below be searched out will I reject all the descendants of Israel.

  71. #71 dmholland
    August 25, 2011

    OKthen @68,
    Sorry about not responding sooner. If I understood you, you hypothisized that matter would attract matter, anti-matter would repell anti-matter and there would be no gravitational force between matter and anti-matter. I was wondering how photons would respond gravitationally in your scenario. Would they be attracted to or repelled by anti-matter for instance? We know they are attracted to matter.

  72. #72 SCHWAR_A
    August 25, 2011

    @dmholland(72) & OKThen(68):
    As far as antimatter can be kept stable for a longer time in usual accelerator/storage rings, I would assume, there is no difference to photons related to matter or anti-matter. All coupling is the same, except that charge is inversed.
    Thus Photons would also be attracted by anti-matter in their gravitational field. We see, gravitation is the same for matter and anti-matter.

  73. #73 dmholland
    August 25, 2011

    SCWAR_A,
    OKthen has a very nonstandard hypothesis on gravity works. I was looking for more details on that hypothesis. I would be very surprised if antimatter didn’t behave just like matter, gravitationally.

  74. #74 Raging Bee
    August 25, 2011

    I may have missed something, but I never heard anything about antimatter responding to gravity differently from matter. AIUI, antiparticles are supposed to have opposite charges and spins from their respective matter-particles; but gravity depends on mass, and antimatter does not have negative mass. (Is negative mass even theoretically possible?)

  75. #75 Wow
    August 25, 2011

    If you have negative mass, then you’d have negative gravity.

    However, that makes no sense, really, so no.

    Not even the complementary particles of gravitons (gravitinos) give us the option of gravitational repulsion, so still no there.

    But we may have something with imaginary mass that is going faster than light (tachyons) that would be repulsed, though whether that would still be attraction in our frame of reference I can’t say.

    E E Smith had a macguffin of negative matter which reacted oppositely, and he thought that positrons (Dirac holes as he correctly called them) were themselves negative matter. Except that a hole is just where matter *isn’t*, not a place where negative matter IS.

    It’s why I don’t think he deserves the “Doc” in the honorific.

  76. #76 Jason Tannery
    August 27, 2011

    Refer to the website address below for the evidence of dark energy: http://news.nationalgeographic.com/news/2008/08/080811-dark-energy.html

    The following is the extract from the above websites under the fourth paragraph:

    The new image reveals the spectral fingerprints created by dark energy as it stretches huge supervoids and superclusters, structures that are roughly half a billion light-years across.

    Dark energy is being defined in http://en.wikipedia.org/wiki/Dark_energy as a hypothical form of energy that permeates all of space and tends to increase the rate of expansion of the universe. Despite there was an image to reveal the existence of something, or the so-called, dark energy, that it could stretch huge supervoids and superclusters even up to half a billion light-years across, it might not provide the truth that the universe could be expanding due to the following possibilities:

    a)The universe itself could be created initially in infinity and there might be no space limit or boundary. If that could be our universe to be since nobody in this earth did ever see any boundary of this universe, the thing that stretches huge supervoids and superclusters, structures to move would not lead to the conclusion that this universe could be expanding. Instead, it simply gives information that something has been causing the huge supervoids and superclusters to move forward.

    b)There could be also the possibility that this universe could be so huge that it could take a few trillion light years for galaxies to travel from one end to another in order to have their return facing us in a few trillion light years later.

    There are a few likeliness that would not give the conclusion that the universe could be expanding by seeing that thing that stretches huge supervoids and superclusters across and there are:

    1)The so-called, dark energy, might simply perform its routine function to cause the huge supervoids and superclusters to be stretched across and yet it is either within the huge boundary of the universe in which it would take a trillion years for the galaxies to travel from one end to another until its final return in advancing to us in a few trillion years later or in the universe that could have been created to be lasted until infinity.

    Let’s refer to another website pertaining to the velocities of the galaxies in advancement: http://www.newscientist.com/article/dn7109-evidence-of-dark-energy-missed-30-years-ago.html

    The following is the extract for the analysis:

    In 1972, Allan Sandage of the Carnegie Observatories in Pasadena, California, US, reasoned that in the nearby universe – where the expansion is at its slowest – the gravitational attraction between groups and clusters of galaxies should produce significant deviations in their velocities from the otherwise largely smooth speed of expansion. These deviations are called “peculiar velocities”, but Sandage pointed out that galaxies in our vicinity – those lying just beyond our “Local Group” of the Milky Way and its immediate neighbours – showed abnormally low peculiar velocities.

    Let’s assume that you would blow a balloon. The air would go from one end and to move in one direction to cause the balloon to expand. However, consideration has to be taken in is the moving speed for all particles in the balloon should be the same regardless whether those particles that are nearby each other or big or small to the ultimate reach of the boundary of the balloon so as to cause it to expand further. There should not be any reason for all particles within the balloon to travel with various speeds despite the particles could be big or small.

    As discovered by Allan Sandage of the Carnegie Observatories in Pasadena, California, in 1972 that there is a significant deviations in their velocities among galaxies, it does not provide a good source to prove the galaxies might be expanding. If there could be a constant force that could cause the universe to be expanded, the moving speed for all the galaxies should be the same in advancing further away from us instead of with irregular velocities that some are advancing faster than another.

    The deviation of velocities of galaxies in advancement is mentioned the same in the website as follows: http://www.universetoday.com/16170/astronomers-find-new-evidence-for-dark-energy/

    The following is the extract:

    When the team compared galaxies against the CMB, they found that the microwaves were a bit stronger if they had passed through a supercluster, and a bit weaker if they had passed through a supervoid.

    As the velocities of all the galaxies have been deviated from each other, it is irrational to be quick to jump into the conclusion that our universe could be expanding so as to use it to support Big Bang theory in which something can be created out of nothing.

  77. #77 OKThen
    August 27, 2011

    Schwarz A & dmholland
    First, my view of gravity is very non-standard.
    But we must remember that gravity has never been measured for antimatter. Gravity is a very weak force, We can not even measure it very well for regular matter.

    Let mee simply explain the basis of my hypothesis, so you can judge it one way or the other for yourself. But remember, no reason a priori or otherwise really matters. Experiment is needed. And when experiment shows something about antimatters relation with gravity , I will accept that,

    OK my hypothesis.
    1) regular matter attracts regular matter gravitationally forward in time. (standard theory so far).
    2) Richard Feynman observed that antimatter behaves like regular matter of opposite electrical charge going backwards in time. ( standard theory so far).
    3) Most physicist (I think) view Feynman’s observation of antiparticles going backward in time as not a physical reality but merely a mathematical short cut for solving problems. (standard theory so far)
    4) I assert that antimatter (at a quantum level) moves backward in time in a physical quantum sense. This is more than a mathematical shortcut; it is a physical insight and clue into the nature of antimatter. (This is my basic first speculation).
    5) Since antimatter (by #4 above) behaves like matter going backward in time. Antimatter would manifest itself (in our forward in time subuniverse) as antimatter repelling antimatter because the quantum interaction is backward in time (even though we interpret it as forward in time). This is my second speculation)
    6) So matter interacts with matter forward in time. (standard physics theory)
    7) So antimatter interacts with antimatter backward in time. (intepretation of Feynman’s as a physical quantum aspect.) (sso mys speculation) Note we do not have enough antimatter to test gravity at the quantum or clkassical level.
    8) If matter interacts forward in time and antimatter interacts backwards in time; then how do matter and antimatter interact gravitationally from a temporal point of view? I assert that they act neutrally. A neutron and an antineutron will neither gravitationally attract nor gravitationally repell. Their curvatures of space will be equal and opposite and cancel producing neutrality. ( My speculative hypothesis)

    So judge it for yourself and I defer to any experts who correct any of my assumptions or can point me to any experiments that invalidate any of my hypothesis.

    dmholland
    You ask, “I was wondering how photons would respond gravitationally in your scenario. Would they be attracted to or repelled by anti-matter for instance? We know they are attracted to matter.”

    I must emphasize again, that my hypotheses are very speculative and as far as I know not shared by mainstream physics. So take them as thought ideas, thought triggers that might provide an insight that leads to a useful hypothesis.

    First, photons follow the curvature of space which is caused by gravity. Thus a photon will follow the curvature of matter or of antimatter.

    But there is a complexity, if antimatter interacts backwards in time and if a photon is its own antiparticle.

    My answer is something like this. We observe only 1 type of photon. However, I believe that QED predicts 4 different types of photons ( I don’t have time to check my references). So how do be resolve this paradox. Well the standard answer is that experiment is correct there is only 1 type of photon; and then the rational is worked out to make this theoretically true. (This is standard theory)

    But I assert that QED’s prediction of 4 photons is correct. However, we have not yet figured out how to distinquish between photons. Without elaborating here on why I believe in 4 photons and my ideas here are in flux. (my speculation)

    So in an matter antimatter annihilation for example two photons are emitted. and we add up all the energy
    positive matter energy (forward in time) + postive antimatter energy (forward in time) = positive photon energy (i.e forward in time) + positive antiphoton energy (i.e. backward in time) i.e. conservation of energy is conserved.
    (Standard theory)

    But why not interpret the same event as follows.
    (positive matter energy forward in time) + (negative antimatter energy backward in time) = 0 (zero) = (positive photon energy forward in time) + (negative photon energy backward in time) Hence conservation of energy. (my thoery unless I’ve mistated my idea but it can be fixed. I’m rushing because of my sceaming baby. (my speculation)

    Similarly, conservation of momentum works and also extra dimensions are needed to have a fully reasoned argument,.

    Net the electron and positrom are the same electron, one going backward in time that reverse direction and then goes backward in time (or vice versa) and similarly (photon and antiphoton). But we can’t distinquishe yet between the photon and antiphoton; as for the other two photons to make the 4 of QED, that is a further discussion. (all of this very speculative).

    It is published not as well articulated as I’d like in my book A Critique of Pure Physics. (available to fully read online on Google books.)In 5 or 10 years I will rewrite. But first I must understand standard physics much better. Why? 1) to try to break my own ideas. 2) if I cannot break them to better articulate them.

    Note they are all very speculative, but sincere. Not I am an outsider not a professional physicist. I say regarding physics, I did not know that everyday. and there are dozens of ideas that I search daily to see if a new experiment has confirmed my theory or buried. Frame dragging was a recent aha experiment that confirmed an idea I had (unaware of gravitomagnetism) that gravity had a force similar to magnetism. But I need to know much more if it is enough to account for what I wish.

    Not most of my speculations I break; the ones in my book I can not yet break. They are far far from what would be called theoretical vetted physics. At best they are somewhat informed scientific and philosophyical speculations; at worst personal sincere speculation with some amount of reason.

    No time to edit.

  78. #78 Collin
    August 28, 2011

    Forrest, IIRC, the ZPF comes from math, and is generally regarded as an anomaly. The standard model as confirmed scientifically has the ZPF “censored out”. Since the ZPF is formally infinite, it doesn’t make sense physically anyway. Ugly, but it works, and we don’t know why.

    I’ve read Peskin’s explanation of the oscillator formalism and how it leads to the Klein Gordon equation plus ZPF. I don’t fully understand it, but it sounds to me like an oscillator is a property of a point in spacetime, and that its canonical position is (at least metaphorically) an extra dimension. Since that dimension is formally unbounded, it takes energy to constrain a bounded distribution within it. And this fails to normalize when integrated over momentum.

    So I think the assumption of unbounded oscillation is the flaw. If, instead of a linear domain, the oscillation goes around a circle, aux Kaluza-Klein, it doesn’t need any energy to constrain itself.

    The problem is how to write this as an equation. It would seem to require a nested exponential, which could be difficult to work with.

  79. #79 Raging Bee
    August 28, 2011

    “Feynman’s observation of antiparticles going backward in time?” When — and how — did Feynman, or anyone else, “observe” anything going backward in time?

  80. #80 OKThen
    August 28, 2011

    Raging Bee
    Of course Feynman was a theorist; but also of course observations are interpreted according to some theory. Hence. Feynman’s theory could be used to simplify otherwise very difficult calculations.

    For example, read the antimatter section of this link
    http://en.wikipedia.org/wiki/Retrocausality#Antimatter
    Most physicists don’t like the interpretation but Feynman did. You can also read his nobel lecture in which he discusses this idea.

    But the key idea is this thinking of antimatter as moving backwards in time can be done consistently; and was an idead used by Wheeeler, Feynman and others.

    By the way, no one has ever “observed” an electron except in the sense of interpreting data in a consistent manner relative to a theory. It is in that sense that Feynman’s interpretation of an antimatter particle moving backward’s in time has been observed. But philosophically physicists do not like that physical interpretation.

    Just so for a long while physicists thought that the Lorentz contractions were just mathematical artifacts; today they are interpreted as physical reality and Einstein gets credit for the special theory of relativity not because he discovered the equations (he didn’t). Einstein get’s credit for asserting that the Lorentz contraction was indeed a physical manifestation.

    In a similar way, Feynman asserted that electrons could go backwards and forward in time any way they wish. I’m sure you can find his quotes. Many physicists questions his interpretation; but none question his mathematical calculations in this matter. They are consistent with observation.

  81. #81 KT
    August 29, 2011

    Thank you very much for your article! I’m no expert, but I thought that MOG was able to explain/predict the CMB data and the Bullet cluster?

  82. #82 Raging Bee
    August 29, 2011

    OKThen: I just read the article you cited. I can’t say I understood much of it, but I did catch the bit about “retrocausivity” only being (theoretically) possible under certain circumstances — which I suspect would rule out antiparticles travelling backward in time when created here on Earth. I may be missing something here, but looks like any theory based on particles going backwrd in time is on shaky ground, and as you said before, there’s not exactly a concensus behind Feynman’s theory.

  83. #83 Tissa Perera
    August 31, 2011

    Dark Matter is most cosmologists play putty. It can be invoked if and when necessary and molded conveniently to accommodate and rectify the observed seemingly abnormal behavior of real matter in order to save Newton’s law of gravity. To explain Dark Matter, certain obvious properties are assigned.
    It must be made of some kind of particles not resembling any of the known particles, more akin to neutrinos, but unlike neutrinos, it must have significant mass(hence gravity), must move slow(cold) and hardly interact physically with each other or with real matter(weakly interacting) except via gravity. I do not know why they had to attribute even a weak interaction with real matter, may be they hoped to physically detect it one day like they did with neutrinos. After so many years this stuff still remains to be detected.
    The problem with such tenuous matter properties is that it cannot congregate into any significant structure except by gravity, and gravity is already a very weak force. Computer simulations have produced vast web structures of this stuff where real matter is supposed to gravitate at the web nodes. But the visible composite structures(Galaxies etc) are moving in space at tremendous speeds. I do not see how the dark matter web nodes flow with the real matter at these speeds without separation.
    Nature may not be that way, how about modifying gravity? I have a different theory of the universe in which an extra cosmic size bounded 4th spatial dimension naturally modifies Newton’s law of gravity at cosmic scales to reproduce and modify the now famous empirical MOND theory. Dark energy becomes a natural consequence of this theory and dark matter is not necessary. This theory basically shows that the so called dark matter is a natural consequence of the bounded curvature of the 4th space where real matter by itself is the cause of so called dark matter. Only gravity can venture into the 4th dimension which I call the dark space. After all, MOND was on the right track and MOND becomes a legitimate theory under this hypothesis.

  84. #84 kj
    September 1, 2011

    Nothing created God/Big Bang, since space and time didn’t exist before God/Big Bang.

    But us Humans created ridiculous beliefs that all religion is insanity or non-Christians go to Hell eternally (infinite punishment for finite crime). It’s up to us to discard such nonsense and discuss topics rationally.

    Why can’t Dark Matter just be slow-moving nutrinos that lack the energy to be detected. Nutrinos have mass, at most 2.2eV = 24000K (note that temperature converts to energy (Boltzmanns constant) just as energy converts to mass through c^2). for the electorn neutrio, but the mass may be higher as measuring it is not easy.

    Relativistic particles lose both number density and energy per particle as the universe expands, so density drop r^-4, compared to slow, massive particles that drop r^-3. At 3000K, photons and baryons had the same mass (coincidence that this is also the decoupling temperature). Number density of neutrinos is about twice that of photons. Lets say neutrinos have a mass of about 15000K. Ignoring the kinetic energy of the neutrinos that will be disapped anyway with the expanding universe, they are 2*15000/3000 = 10 times the density of baryons. This 10:1 density will stay as the universe cools. That could be dark matter but there some problems with this idea.
    Combine this idea with possible mundane explanations (heavy dust that also hides stars, etc) and it may have merit.

  85. #85 Tom
    September 3, 2011

    I really like your blog and the way you question what needs to be questioned. There is a theory that explains dark matter and still fits with good old redshift and CMBR, it’s called Contracting Matter Theory.

    According to this dark matter is matter that has contracted beyond the point at which it can form structure like atoms etc. There would have been several “big bangs”.

  86. #86 Jason Tannery
    September 17, 2011

    Big Bang theory has been used to support that this universe could be formed out of chaos.

    Refer to the website address, http://csep10.phys.utk.edu/astr161/lect/history/newton3laws.html, regarding to the 1st law of Newton’s Principle. It is mentioned that every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it. If this concept has been applied to the formation of this universe, it implies that this universe would remain nothing as it was until external force that would cause it to change. Or in other words, if there could be no external force or substance that could cause the formation of this universe, everything would remain as it was and the universe, that would remain nothing, would continue to remain nothing.

    If this universe could be created something out of nothing, there must be the external force that would cause something to be created out of nothing. Stephen Hawking might comment that it was gravity or quantum theory or etc. However, there must have external force that would cause gravity or quantum theory or etc., to be at work. If there would not be any external force to cause gravity or quantum theory or etc., to be at work in the formation of this universe, how could there be the formation of this universe since this world would remain nothing until eternity as supported by 1st law of Newton’s principle? Thus, the concept that this universe could be created something out of nothing is questionable from scientific point of view.

    Even if one insists that this theory could be correct, how could quantum theory or gravity or etc., be so efficient to manage the universe well in such a way that it could create sophisticated earth which plants and animals could survive here? What made the earth to be created far from the sun and not just next to it? For instance, if this earth was created a short distance just next to the sun, all animals and plants would not survive. Thus, the creation of this universe could not be co-incidence and this certainly puts quantum theory to be in doubts pertaining to its creation from something out of nothing.

  87. #87 Jason Tannery
    September 19, 2011

    Refer to the website address, http://en.wikipedia.org/wiki/Introduction_to_general_relativity, pertaining to general relativity. It is mentioned in this website 6th line after the title of ‘’Introduction to general relativity’ that the observed gravitational attraction between masses results from their warping of space and time. As the phrase, gravitational attraction between masses results from their warping of space and time, is mentioned for general relativity, it gives the implication that there have to be some kind of masses in order to create gravitational attraction through warping of space and time. Thus, it opposes Stephen Hawking’s theory that gravity or dark energy could exist prior to the formation of this universe at the absence of masses or objects in order to create something out of nothing. Or in other words, in order that gravitational force or dark energy would exist, there must be masses in this universe to interact in space and time in order to generate gravitational force.

    Refer to the above website 17th line after the title of ‘Introduction to general relativity. It is mentioned that general relativity also predicts novel effects of gravity such as, gravitational waves, gravitational lensing and an effect of gravity of time known as gravitational time dilation. Let’s examine all these factors, i.e. gravitational waves, gravitational lensing and gravitational time dilation below:

    Refer to the website address, http://en.wikipedia.org/wiki/Gravitational_wave, pertaining to gravitational waves. It is mentioned in this website 10th line after the title of ‘Gravitational wave’ that the existence of gravitational waves is possibly a consequence of the Lorentz invariance of general relativity since it brings the concept of a limiting speed of propagation of the physical interactions with it. The phrase, Lorentz invariance of general relativity…brings… the physical interactions…, here gives the implication that gravitational waves have to be dealt with physical interactions or masses. As gravitational masses have to be dealt with masses, it opposes Stephen Hawking’s theory in which Hawking mentioned that gravitational wave could exist at the presence of substances or masses prior to the formation of this universe. As gravitational waves have to be dealt with substances or masses, it is irrational for Stephen Hawking to use it to support that gravity or dark energy could exist at the absence of masses so as to create something out of nothing.

    Refer to the website address, http://en.wikipedia.org/wiki/Gravitational_lensing, pertaining to the gravitational lens. It is mentioned that a gravitational lens refers to a distribution of matter (such as a cluster of galaxies between a distant source (a background galaxy) and an observer, that is capable of bending (lensing) the light from the source, as it travels towards the observer. The phrase, a distribution of matter (such as a cluster of galaxies) between a distant source (a background galaxy) and an observer, gives a strong proof for a must to have matters or substances in order to activate a gravitational lens. Thus, gravitational lens in general relativity needs to rely on masses or substances in order to be generated and this opposes Stephen Hawking’s theory that gravity could exist at the absence of substance to create something out of nothing.

    Refer to website address, http://en.wikipedia.org/wiki/Gravitational_time_dilation, pertaining to gravitational time dilation. It is mentioned that gravitational time dilation is the effect of time passing at different rates in regions of different gravitational potential; the lower the gravitational potential, the more slowly time passes. Albert Einstein originally predicted this effect in his theory of relativity and it has since been confirmed by tests of general relativity.

    Refer to the website address, http://en.wikipedia.org/wiki/Gravitational_potential, under the sub-title of ‘Potential energy’ pertaining to gravitational potential. The following is the extract of the formula of gravitational potential:

    The gravitational potential (V) is the potential energy (U) per unit mass:
    U = mV
    where m is the mass of the object. The potential energy is the negative of the work done by the gravitational field moving the body to its given position in space from infinity. If the body has a mass of 1 unit, then the potential energy to be assigned to that body is equal to the gravitational potential. So the potential can be interpreted as the negative of the work done by the gravitational field moving a unit mass in from infinity

    From the above formula above, it is obvious that U (the potential energy or dark energy or gravity) has a direct relationship with m (the mass of the object). If m = 0, U (the dark energy would turn up to be 0 since U (the potential energy) would turn up to 0 whatever the number that V has when V is multiplied by m that is equal to 0. Thus, the generation of potential energy in general relativity would certainly have found to have conflict with Stephen Hawking’s theory in which dark energy or gravity could exist at the absence of masses or substances prior to the formation of this universe so as to create something out of nothing.

    Nevertheless, Stephen Hawking has abused general relativity to support his quantum theory in which something could be created out of nothing since general relativity demands masses or substances in order to generate dark energy or gravity.

  88. #88 Wow
    September 19, 2011

    “As gravitational masses have to be dealt with masses, it opposes Stephen Hawking’s theory in which Hawking mentioned that gravitational wave could exist at the presence of substances or masses prior to the formation of this universe.”

    No, it doesn’t do that.

    “If this concept has been applied to the formation of this universe, it implies that this universe would remain nothing as it was until external force that would cause it to change.”

    Problem: the universe isn’t a Newtonian theory. It’s a universe.

    “Stephen Hawking might comment that it was gravity or quantum theory or etc. However, there must have external force that would cause gravity or quantum theory or etc., to be at work.”

    I suspect that Stephen Hawking might have considered this rather more carefully than you have.

    And I suspect you’re rewriting what he says to fit your requirements.

    Look, we KNOW that both Quantum Mechanics and General Relativity are, to some extent, wrong, because they give different answers to, for example, gravity’s effects.

    Therefore the fact that one (GR) makes the other (QM) wrong is no more proof that QM is being abused than the fact that QM makes GR wrong proves GR is being abused.

  89. #89 Wow
    September 19, 2011

    “It is in that sense that Feynman’s interpretation of an antimatter particle moving backward’s in time has been observed. But philosophically physicists do not like that physical interpretation.”

    One of the reasons being that it gets difficult to get antimatter to cooperate in its annihilation: you get into the problem of “unwhisking an egg”.

    It’s very much easier to whisk an egg because you’re not trying to get any specific rearrangement of the egg components out of an absolutely trans-astronomical number of possible arrangements.

    However, to unwhisk that egg, you need to select EXACTLY THAT ONE arrangement.

    For ideas like this, their proof has to proceed along lines like:

    If this is what is REALLY happening (as far as anything can be said to be in a model of the universe), then the consequence of this will be THIS departure from the observation if it is not correct.

    See, for example, the Lamb Shift or the “proof” of GR with observations of the displacement of a star near the sun in solar eclipse.

    A discernible difference calculated: a proof can be made.

  90. #90 James T. Dwyer
    January 4, 2012

    Ethan:

    You stated:
    “Every galaxy gets outfitted with a halo of this dark matter, and this fixes the problem of it rotating (or winding up) too quickly on the inside.”

    This is the exact opposite of the correct description of the galaxy rotation problem described by Vera Rubin in the 1970s: the rotational velocity of the disks of spiral galaxies were found to remain relatively constant as a function of their radii. It was the stars at the periphery of spiral galaxy disks that were rotating faster than expected, based on Kepler’s ‘laws’ of planetary motion. Please see: http://en.wikipedia.org/wiki/Galaxy_rotation_problem

    It was Rubin and her collaborators who originally established that basis for the perceived requirement for dark matter in the universe among astrophysicists in the 1970s and 1980s.

    Unfortunately, it was not recognized that Kepler’s laws of planetary motion had already been determined by Newton to apply only to the highly centralized mass configuration of the Solar system, where 99.86% of total mass is contained within the Sun, and not the highly distributed configuration of mass found in spiral galaxies.

    It has since been determined that the rotational characteristics of spiral galaxies can be described using Newtonian dynamics and universal law of gravitation, without dark matter or modified gravity. Please see: Feng & Gallo, (2011), “Modeling the Newtonian dynamics for rotation curve analysis of thin-disk galaxies”, http://www.raa-journal.org/raa/index.php/raa/article/view/858

    Please also see a brief commentary including several other references: http://sciencewithoutfiction.com/uploads/JDwyer.PDF

  91. #91 GH
    March 7, 2012

    Why must dark matter be non-baryonic? Do we really need dark energy to explain anything?
    Can any of these be alternatives:
    a) the universe is older than we think
    b) black holes are more common than we think
    c) brown-dwarves, white-dwarves and dead stars are more common than we think
    d) planets are everywhere and more common than we think
    e) neutrinos are more common than we think
    f) heat applies more force on galaxies than we think

    Any of this would be better than swallowing the dark-matter koolaid. If you want to convince us that dark-matter is special, explain why it must be most of the universe but not here. Explain why our corner of the universe doesn’t contain any dark-matter but contains bunches and bunches of matter that we might not be able to detect if it was orbiting the next star over.

    And people seem to think they know the age of the universe from watching it a few years. A bad reading of the age of the universe might explain things. It would be easier for me to accept a poor reading of age than to adopt the dark-matter panacea.

    If the universe isn’t much older than we’ve already guessed, then maybe those first-generation stars were more likely to produce black-holes than we would otherwise think. Apparently, this first generation was a cohort of huge, hot monsters, burning out after just a few million years. If a fraction of these behemoths became black-holes, they would be among the most massive bodies in space, or so one might presume. If they were numerous, then their invisible children might also be numerous. With such a short life cycle, there would have been time for many, many generations.

    But black holes aren’t the only star-like bodies we might not expect to see. Why shouldn’t the population of stars include any number that we can’t observe directly? Would we notice planets orbiting a browner-than-brown star? Something that hasn’t quite collapsed or emits energies otherwise absorbed?

    If planets were more numerous than stars – much more numerous than stars – we still wouldn’t know it. Our neighbors are sometimes big, sometimes small, but would all be difficult to notice if not for Sol. The odd orbits of some of our sister planets might even suggest that they were captured from otherwhere. Planets form readily from dust and debris, take up orbits and hardly ever interact again. While stars die, planets might not.

    If neutrinos are formed in the stars, carrying away energy from nuclear reactions, and if our stars have processed most of the hydrogen in the universe, then it would seem possible that there are a heck of a lot of neutrinos out there. With more time, more neutrinos. Off they go into the vast universe.

    Until they smack into another star, just like the rays of light they follow (close behind), neutrinos act as a carrier of energy that another star can really appreciate. The denser the target, the more likely the push.

    Neutrinos are one way that a star can push another, but not the only way. Anything we can see in the sky is pushing on us, nudging us and everything else away. All the forms of light are energetic. Even if there weren’t rivers of solar wind, gamma-rays and ions spewing from every hot body toward every other thing, it would accelerate us outward.

    Please help me understand why none of these candidates can unseat the eight-hundred pound invisible gorilla. I very much want to agree with everyone – it would be great to understand – but I find that I am still in the dark.

  92. #92 Dave
    New Zealand, Earth
    August 25, 2012

    That picture of dark matter looks like living tissue to me, I think the universe must be a living organism based on this impression (Ivan Illich (author of ‘Deschooling Society” 1971 which anticipated the internet) believed the universe & everything in it was the evolving god, he was right about everything else).

  93. #93 Wow
    August 25, 2012

    Dave, don’t let analogies fool you. Your sort of thinking led to victorians buying lenses to “focus the cold”. It also led people to believe in the aether, because other waves had a medium they flowed through.

    Ivan’s thoughts are also those of a standard pantheist. And I’m pretty certain you’ll find he was wrong about a good many things as he would have freely confessed himself.

    Just because Freeman Dyson had many many good ideas in his life, doesn’t mean he’s always right. That’s how the fallacy of appeal to authority starts (they have to be a false authority or unoppposed by their peers to be a useful appeal to authority).

  94. #94 colinrobot
    worcester eng
    November 11, 2012

    im here…. i just thought that maybe dark matter is the excrement of matter /universes .. take a dwarf star its been compressed so much the very gaps between are being squeezed out making it almost as dense as a black hole but not dropped into the hole… sorry hahahha

  95. #95 random_idiot
    Somewhere
    February 17, 2014

    Is there at least hypothesis about е”empty space”? What the hell is space? I mean you physicists talk about “it has geometry” ,”it expands” almost like these expressions are self explanatory. What has geometry, what expands? Are these its only properties?How it expands? For a nothing, vacuum or whatnot it does hell of a lot stuff.

  96. #96 Sinisa Lazarek
    February 17, 2014

    @ random_idiot

    “Is there at least hypothesis about е”empty space”?”
    -yes, quantum field theory and vacuum state.

    “What has geometry, what expands? Are these its only properties?How it expands?”
    This is part is not quantum mechanics but general relativity. You will have to read some basic concepts about general relativity in order to understand that part about geometry and expansion.

    ” For a nothing, vacuum or whatnot it does hell of a lot stuff.”
    Indeed it does.

Current ye@r *