This is an enhanced version (with some upgraded images and text) of an article I first wrote over two years ago. It is just as valid today as it was back then, only today, I have a special offer to go with it. Next week, a bunch of cosmologists and myself are getting together and all writing about dark energy. And I want you to have your say.

So at the end of this post, ask your dark energy questions. Ask anything and everything you ever wanted to know about dark energy. I’ll choose the best one (or, space & time permitting, more than one) and write a special post on it for you then. Enjoy the read, and then let’s see what you’ve got!


“This is what science is all about; getting thrown a curveball by Nature and plunging in to find out what’s going on”. -Andy Albrecht

Imagine waking up in the morning and heading out into the sand dunes. They never look exactly the same from day to day. But each day that you go out, they’ll look somewhat like this.

Desert Sand Dunes Tracks

Image credit: Desert Sand Dunes Track by Jon Sullivan.

You consider yourself smart and well-informed, and you have a sense of adventure. So each morning, you venture out a little farther into the dunes. You find a variety of different features, but everything pretty much just looks like, well, sand dunes. Plain, ordinary sand dunes. Yes, they shift in detail over time, but nothing ever appears out of the ordinary.

One day, however, all of that changes. You venture out farther than you’ve ever gone before, and you see something that simply bewilders you.

Dino footprints

Image credit: DinosaurHunter.org, retrieved from the USGS.

Something like this, that appears to be dinosaur footprints! Well, suddenly you have this huge problem in front of you! On the one hand, you know that dinosaurs have been extinct for 65 million years. On the other hand, you examine these footprints, and you find that they’re fresh. You walk around more, and you discover that this area is covered in dinosaur footprints. The tops of the dunes, the deepest valleys, the rolling straightaways, all of it.

So what do you do? How do you make sense of this? I mean, it seems that there are two major possibilities. Either these footprints were left by a creature that is going to cause you to drastically change your worldview,

Godzilla munching on a train

Image credit: Godzilla the motion picture, by Ishirō Honda, image retrieved from Will Dodson.

or something — perhaps a roguish person, a coincidence of unlikely natural events, or a poorly understood phenomenon — is conspiring to make the land appear like it’s inhabited by a creature that, according to your present understanding, doesn’t and shouldn’t exist.

But which one is it? Has your conception of nature just been turned on its head, and are you going to have your foundations rattled, or is something deceiving you? In other words, you might find yourself asking the following question:

Is what you’re seeing indicative of a fantastic, paradigm-shifting theory, or is there another, more mundane cause for the effect you observe?

 

Not quite "real" dinosaur footprints

Image credit: Julie of Fireflies and Tadpoles.

In the case of dinosaur footprints, you may be much more likely to think that you’re being deceived. And I’m the same way. If you’re anything like me, your intuition in this situation will tell you that you need lots of hard, convincing evidence before you’re ready to change your worldview so drastically.

Coming into that situation, it’s probably fair to say that you didn’t expect you’d be believing in the highly improbable, but now you’ve got a mystery to solve. While this dinosaur situation never actually happened, this is essentially what happened to cosmologists in 1998, when the first evidence for dark energy was discovered. We had measured the expansion rate of the Universe relatively nearby, and had figured out what the Hubble constant was. But at this point, we didn’t know what the fate of our Universe would be. But we could figure that out, if only we knew what the contents of the entire Universe were. We looked at extremely distant supernovae, trying to discover what the expansion rate of the Universe was in the past, and hence, what the fate of our Universe would be.

Expansion of the Universe

Image credit: NASA / WMAP science team.

Would the Universe recollapse, like the yellow line shows? Would it expand off into infinity, watching its size increase ever-so-slowly as the expansion rate drops to zero, begging for just one more proton, as that would be enough to cause a recollapse, like the green line? Or would it expand off into the abyss of emptiness, like the blue line? In any case, it would never follow that ridiculous curve shown by the red line; nobody even considered that. Yet in 1998, the data came in, and of those four cases, what did the data indicate?

Supernova Cosmology Project

Image credit: Supernova Cosmology Project, S. Perlmutter et al., 1998.

Well, it was hard to tell, but it was more consistent with the red line than any others. You couldn’t rule out the blue line, and the green line was pretty inconsistent, but it was hard to tell. When I started graduate school in 2001, more evidence had rolled in, but I wasn’t ready to believe it yet.

LSST Dark Energy

Image credit: Large Synoptic Survey Telescope, NSF, DOE, and AURA.

Yet of the four major possibilities, the last one — that we lived in an accelerating, dark-energy-filled Universe — was suddenly one that needed to be taken seriously.

But, like I said, I wasn’t ready to buy it just yet. I needed to find out more information first, and I approached it the same way I’d approach the dinosaur footprint situation: assuming that there was an alternative explanation for why we observe this oddity.

Bok Globule containing HH 46/47

Image credit: NASA / JPL-Caltech / Spitzer Space Telescope, of a Bok Globule.

The possibilities exploded both in my mind and in the scientific literature of the time.

  1. Could something be blocking the light from back then? In other words, was there some new form of “grey dust” that could block the light from these extremely distant supernovae, equally at all wavelengths?
  2. Could supernovae have been intrinsically different when the Universe was so young? Could some fundamental physics have been different billions of years ago, causing an intrinsic difference in the Type Ia supernovae at incredibly high redshift?
  3. Could perhaps the supernovae have been the same, but the environments in which they detonated were different, giving an intrinsically less bright explosion?
  4. Could something be happening to systematically remove a fraction of the light (like photon-axion oscillations) that mimic the effect of dark energy?

I looked at these and other alternative explanations — in incredible depth — and it turned out that they just couldn’t account for what we saw. (See my recent dark energy series.) More distant supernovae ruled out possibilities 1 and 4, while evolutionary effects were inconsistent with other high-redshift observations.

Hubble Space Telescope view of a distant galaxy cluster

Image credit: NASA / ESA / A. Gonzalez, A. Stanford and M. Brodwin.

In the meantime, data from other sources was rolling in. The cosmic microwave background, galaxy clusters, and many other distance indicators all pointed towards a Universe that was inconsistent with physics unless it had dark energy in it. By 2004, it was clear that even if the supernovae observations didn’t exist at all, we would still have enough evidence to strongly favor dark energy over all other cosmological models.

Dark energy composition of the Universe

Image credit: NASA, retrieved from universe-review.ca.

It took a little over three years to convince me to start to change my beliefs, and to accept dark energy, but it was coming along, and I certainly had moved from the “No way is this thing right” camp into the “Wow, there’s a lot of evidence for it and no real wiggle room to get out of it” camp. The nail in the coffin (for me) came when a very smart man proposed an interesting alternative explanation for dark energy. While researching whether his explanation was feasible or not (and — while it’s an interesting idea — I concluded that it’s not, and even got a good paper out of it), I really became very well-informed about dark energy, its alternatives, and its implications, among other things.

It suddenly occurred to me that if you wanted to eliminate this one thing, dark energy, it would take a minimum of six separate observations to be overturned. And that was it; it was suddenly unreasonable to me that I would reject dark energy. But it took three to four years of studying it intensely, becoming some type of expert in it (as much as one can be), and writing papers right on the cutting edge of the science to convince me. It’s the only scientific conclusion I’ve had in my life where I’ve had to reject it and take up the antithesis of my original position, based on new observations.

Dark energy expansion

Image credit: NASA / STScI / Ann Feild.

And now, today, I defend dark energy, because I understand why we need it. So don’t believe that dinosaurs exist just because you’ve found footprints. But when you’ve exhausted all other alternatives, and you’ve found lots more evidence for them, don’t cling too dearly to your old beliefs in spite of the new evidence. (And no, there aren’t dinosaurs in the dunes; I made that part up.)

One does not simply

Image credit: Quickmeme.com. And yes, of course I generated it myself.

So choose your experts wisely, don’t be afraid to challenge even your most cherished beliefs about how things work in the face of new evidence, and now that you’ve come this far, let’s hear it: what else would you like to know about dark energy?

Comments

  1. #1 Richard Latham
    Melbourne, Australia
    July 19, 2012

    Where is the dark energy coming from in an expanding universe? It seems to violate the laws of energy conservation.

    By the way, I have really enjoyed the last 2 posts, not that I don’t enjoy them all.

  2. #2 anatman
    July 19, 2012

    in articles about the nature of dark energy, i frequently see “quintessence” mentioned as one possibility. i’ve never seen any explanation of what that would be. in my present state of knowledge, the word might as well be “magic”. assuming it is legit (i.e. not a handwave or ether redux) can you give us some idea of what it is?

  3. #3 James G.
    Ohio
    July 19, 2012

    In your opinion, what length of timeframes and advances in technology do you relatively think it’ll take to underdstand dark energy beyond just observing its effect on the expantion of the universe? Is there ANYTHING beyond its outward energy and amount present in the universe that we can even guess about this elusive and mysterious ‘thing’? Or do you believe that it might take a completely new and unfamiliar paradigm of thinking to even begin to truely understand it?

  4. #4 Dave Dell
    Lincoln NE
    July 19, 2012

    How does the previous post about a universe being so flat flat flat that there could be trillions of years of expansion enter into this?

  5. #5 luke lukas
    houston, texas
    July 19, 2012

    Assuming we ever can truly “understand” Dark Matter or Dark Energy, what advances might this understanding provide the “average” person?

    In other words, would we finally have hoverboards if we really figure out what dark energy is? Or lightsabers? (Silly examples but honest question about “what’s in it for me” other than just “cool we know what it is now”).

  6. #6 Jordan Brooke
    California
    July 19, 2012

    1) Could Dark Energy be the final stage of light? I learned in High School (provided my memory serves me right) that as light travels and expands it moves further along the spectrum and that the universe is filled with Cosmic Microwave Background Radiation. Could Dark Energy be that radiation? It would explain why there is so much, the longer the universe is around, the more of it we will have in abundance.

    2) Could Dark Matter be the fertilizer in which “regular” Matter manifests itself?

    3) Do you suppose there are Dark Matter counter parts to every naturally occurring element in our periodic table?

    4) Does Dark Matter cancel out Matter? If I shook hands with an Alien based on Dark Carbon, would we both die?

    I fear these may be dumb questions. But I thank you for your consideration.

  7. #7 Donovan
    United States
    July 19, 2012

    What is it? I don’t mean specifically, since that’s rather easy to answer (“Dark energy. Weren’t you listening? Next question.”). I mean, how can we think of it? Is it like other energy? Is it unaccounted for? Maybe some other universe blowing wind into ours? Is Dark Energy just all the bad thoughts humans have, like in Ghost Busters II? The reason I have a hard time accepting Dark Energy is because I have no idea what I’m even supposed to be thinking of. As anatman said, it seems like so much “Abra Kadabra!” and poof, an F appears on my physics test.

  8. #8 Jeffrey Boser
    Las Vegas, NV
    July 19, 2012

    Why is it called, dark ‘energy’? Does it have any property at all that is energy-like? Is it just the potential energy of something expanding in an unresisting place, like a compressed gas? Is the only work this energy does, the storing of potential energy against gravity?

  9. #9 Erol Can Akbaba
    Turkey
    July 19, 2012

    Is there a known (or suspected by a theory) connection between dark energy and fundemental particles?

  10. #10 Jeff
    Oklahoma
    July 19, 2012

    I like Donovan’s question.

  11. #11 Able Lawrence
    July 19, 2012

    Can dark energy be interstellar magnetic field which should not exist but seem to exist based on studies of light polarisation
    And what about the predicted extra long wavelength electromagnetic waves from the original equations without Lorenz guage condition as proposed by Jimenez in Arxiv
    As for dark matter what about primordial neutrinos. What would be the implication of Pauli

  12. #12 Bobby van Deusen
    Pensacola, FL
    July 19, 2012

    My son Jack, who is now 14 and has been reading Ethans blog for some years now, posits an interesting hypothesis. There are no ‘one way’ energies in the universe, at least according to Newtonian physics. If the universe is accelerating, where is the equal and opposite reaction? Oh, and please inform Dr. Rocky that the Cubs are the same aliens from Carl Sagans “Contact” and have no connection whatsoever to real baseball.

  13. #13 Michael Kelsey
    SLAC National Accelerator Laboratory
    July 19, 2012

    Is there any plausible experimental handle on dark energy? Any reasonable way, either on the ground, or at least on Solar-system scales, to directly interact with whatever it is?

    I’m involved with CDMS, a dark matter search, and while our prospects for anything beyond yet another limit are slim, we can at least _imagine_ successful direct detection of non-baryonic (dark) matter, by our or some similar means.

    But I don’t see any analogous program for dark energy/Lambda/quintessence. My understanding is that if dark energy is a scalar field (a la the inflaton) it lives up at either the GUT or Planck scale, and there’s no hope of producing “particles” the the way we’ve done with Higgs’ scalar field. Am I missing something?

  14. #14 Jon
    July 19, 2012

    Is Dark Energy a fundamental force of nature? If so, is it possible that its interactions are governed by a specific particle or more of an effect of mass like gravity? Or is it some other force we do not understand? Either Dark matter falls under the parameters of the now complete standard model or it is a force. or no?

  15. #15 crd2
    July 19, 2012

    I heard an idea which i thought was very intersting and want to know if its one thats taken seriously or can be tested. Something along the lines of when the big bang happened photons were traveling with so much energy that they were able to move freely into extra dimensions, however as the photons cooled and lost energy, they became trapped in higher dimensions of space because they no longer have the energy to get back out.

  16. #16 Alan
    New Zealand
    July 19, 2012

    So Hooke and Huygens weren’t so naive after all.

    Sounds like ether to me.

    :)

  17. #17 BillK
    London, UK
    July 19, 2012

    I understand that our Universe is very very big, and increasing.
    Where is all the new space coming from?
    i.e. What is in the new space that is forcing things farther and farther apart?

  18. #18 wow
    July 20, 2012

    That’s a bit of a strawman there ethan.

    Nobody’s said you simply believe in dark matter, just that it isn’t a theory, just a working hypothesis using a metasyntatic variable as a placeholder for when the phenomena’s cause is more known.

  19. #19 wow
    July 20, 2012

    Bill, space isn’t getting bigger, the distance between thinds are.

    Monkey brains weren’t designed to think this way and its confusing (which is true of the scientists involved too, hence the use of an abstract but precise language to talk of it – maths)

  20. #20 BillK
    July 20, 2012

    @wow
    Agreed the distance between things is increasing. But that implies the total volume of our universe is also increasing.
    So where is the stuff coming from that is filling in the gaps?
    Is this new dark energy being created that is strong enough to overcome gravity attraction between galaxies?

    It seems that empty space is not actually empty. Some sort of ‘space-time froth’? If it is energy that is in empty space, is more energy being created? Or is existing energy increasing in volume?

  21. #21 Sinisa Lazarek
    July 20, 2012

    I am not sure I am able to formulate my question about DE in one sentence because it’s related to some more fundamental question I have, but I’ll try anyhow :) So here it goes:

    All the experimental observations we have of the Universe I take as correct here i.e. expansion and acceleration. I focus on the theory behind it. Namely the flat curvature and friedmann equation. Or more precisely the critical density and the general density parameter of the Universe (for which we need DE since we seem to lack a lot for critical density in our observable Universe). As a bonus, this is tightly connected to Ethan’s last post on the size of the Universe.

    Ethan, in your last post you say: “Even taking the minimum allowable estimate for the size of the Universe means that, at most, less than 0.0001% of the volume of the Universe is presently or will ever be observable to us.”

    Now the density parameter is defined as a ratio between observed density (our visible universe more or less) and critical density (the whole universe more or less). Wiki says that for a flat Universe we need about 5 atoms per cubic meter of critical density, and in our observable universe we have about 0.2 as far as barionic matter goes.

    My question is basically why the need for DE? The whole universe can still be homogeneus and isotropic on the largest scale but have fluctuations on small scales. Just like CMB does. If our whole observable universe is 0.0001% of the whole sample, we are statisticaly insignificant. There might be regions of Universe (not our observable, but outside of our light cone) which have critical densities of 7 or 8 atoms per cubic meter or more, there might be some that have less than what is in our observable region etc.. On overall it can be 5 atoms per cubic meter on average, and for nothing to change in our observable region. Our observable universe might not be a perfect “statistical average” of the whole Universe. In fact, there is nor reason for it to be that. I agree that it seems there’s missing mass/energy in our observable part and the biggest part of it we call generically “dark energy”. But is it really a single thing? There could be tens of different contributing factors in the rest of the universe giving mass/energy that we are completely oblivious about simply because we can’t see them.

    The CMB is great for visually representing this. If we imagine our observable universe as a blue spec in it, and let’s say we are surrounded by more reddish parts (parts with larger densities), wouldn’t they i.e. cause slight gravitational attraction in every direction around us? Wouldn’t we as parts of that bluish speck observe that as accelerated expansion of our own bluish spec? The whole Universe is still homogeneus, just like CMB is, but our little blue spec in it (or 0.0001%) is only a pixel of the whole thing. And by looking at only a pixel, we can’t infer the whole image.

    I understand the need for DE in explaining the observations of our observable universe, but the equations seem to deal with the whole universe, not just our miniscule observable part.

    So I guess the summary question would be how can we fairly judge the density of the whole universe, by just being able to measure 0.0001% of it?

  22. #22 Bruce Crossan
    Lebanon OR
    July 20, 2012

    1. Was dark energy/matter present when the big bang occurred? If so, how do you know; if not, where did it come from?

    2. If you shoot a cannon ball strait up, with enough force (assuming no interference from other objects in the solar system blah blah), it will increase its velocity as both air density and the attraction of the earth’s gravity decrease. How do you know that the same type of thing isn’t happening to the universe? Would that not eliminate the need for dark matter/energy?

    3. If you’ve only just confirmed the existence of the Higgs boson and if it is the particle/field that gives things mass, how do you know that the Higgs field is uniform throughout the universe? If it is not uniformly distributed, wouldn’t that eliminate the need for dark energy/matter?

    4. If the multi-verse theory is correct, couldn’t there be energy or matter leaking into our universe, from one or more alternate universes? Are the other mult-verses definitely excluded from absolutely all contact with other multi-verses or is the infinity of other multi-verses not a big enough infinity to allow even a very small overlap?

    5. What difference does it make if the unidentifiable stuff in the universe is matter or energy? How do you know that there are two flavors of something, if you don’t have a clue as to what it actually is to start with?

    Thank you Ethan, for taking the time to make some of the complex working of the universe accessible to the curious. Let your imaginations run wild trying out new ideas; just be honest enough to ‘fess up about what is actually provable and what is smoke and mirrors. bc

  23. #23 Stackpole
    July 20, 2012

    Do the theory types see any relation or connection, via E=mc^2 or something more esoteric, between your dark energy pushing thing apart and dark matter holding things together, as they rotate “too fast”?

  24. #24 Wow
    July 20, 2012

    “But that implies the total volume of our universe is also increasing.
    So where is the stuff coming from that is filling in the gaps?”

    Nothing is filling in the gaps. The gaps remain. Bigger. Longer. Uncut.

    As it were…

  25. #25 chelle
    July 20, 2012

    I believe that you might have to reconsider the Big Bang theory and the expansion of the Universe out of a singularity, and reintroduce an Aether theory, it would renormalize a lot of things, such as a really, really, REALLY flat Universe.

    One might have to look at redshift as an *effect* of the continues expansion of our own influence in the universe, considering the Heisenberg-principle that we influence the measurements of the experiment; there is an ever expanding gravity field, and an ever expanding field of light and X-rays that is being emitted for billions of years by our own Sun and our own Galaxy, filling more and more space with our Energy.

    Dark Matter and Dark Energy would be no other than the expression of the pressure, temperature and tension within and between the matter that makes up the Aether. Look at the double-slit experiment and the mystery of Wave–particle duality, there is no need to look at the stars to find answers for Dark Energy, the answers might all be right here in front of our nose. The same goes for the Higgs-field and Higgs-mechanism, when including an Aether it all makes a lot more sense.

  26. #26 Wow
    July 20, 2012

    chelle, try it.

    If it works, publish it.

  27. #27 Eric Lund
    July 20, 2012

    I’m going to refine Stackpole’s question @0344. Yes, Stackpole, there is such a relation. Dark energy has a pressure to it which somehow (I am hazy on the details; this is not my field) combines with mass density in the calculation of the gravitational field. So I would modify Stackpole’s question as follows: How does the pressure of dark energy relate to mass density?

    Several posters above have asked about flatness. One thing Ethan neglected to mention, in either this post or the previous one, is that Ω = 1 is a predicted effect of inflationary cosmologies. IOW, if the observable universe is flat then the rest of the universe should be flat as well. The error ellipse on the values of Ω_m and Ω_v includes Ω = 1.

  28. #28 bobh
    July 20, 2012

    I like the statistical question by S Lazarek. My question is: What fundamental assumptions are made in dealing with dark matter and dark energy? Both of these topics are about distance and velocities i.e. distance and time scales. Understand the assumption of standard candles to measure distance, which may or may not be true. Does the hypothesis also require a constant velocity of light or a constant time scale? Would additional physics be hidden behind such assumptions?

  29. #29 Mu
    July 20, 2012

    I defend dark energy, because I understand why we need it.
    Actually, the only people who need it are the once that don’t want to admit that their model is simply wrong and start over. Same as dark matter was “needed” to explain the observed gravitational attraction with the existing baryon synthesis model. But then, it took 50 years from Maxwell to Einstein for people to realize you didn’t need aether.

  30. #30 Wow
    July 20, 2012

    “But then, it took 50 years from Maxwell to Einstein for people to realize you didn’t need aether.”

    Michelson-Morley experiment, an attempt to detect the velocity of the Earth with respect to the hypothetical luminiferous ether, a medium in space proposed to carry light waves. First performed in Berlin in 1881 by the physicist A.A. Michelson, the test was later refined in 1887 by Michelson and E.W. Morley in the United States.

    Maxwell, J.C., A Treatise on Electricity And Magnetism – Volume 1 – 1873 – Posner Memorial Collection – Carnegie Mellon University

  31. #31 Sekhar
    Plainsboro, Newjersey
    July 20, 2012

    Like there is an equation for regular matter and regular energy E = M*C^2, can there be a relationship between Dark Matter and Dark Energy like that ?

  32. #32 OKThen
    Curiousville, Earth
    July 20, 2012

    Yes dark energy is not a belief; it is a working scientific hypothesis that brings together “a minimum of six separate observations”.

    OK, my three questions>
    1) What are the six+ separate observations supporting dark energy? (Reading this post, I find four).
    2) What are the leading candidate explanations for dark energy? –2a) is a corrollary question: Which of the dark energy explanations involve standard model elementary particles and which dark energy explanations require particles in addition to the standard model particles?

  33. #33 David Larom
    San Diego, CA
    July 20, 2012

    Thanks for a very informative article. Perhaps you are with me in being philosophically offended by dark energy. I was very attached to the idea of an expanding and recollapsing universe, which would validate ideas of cyclical time that seemed sort of cool and symmetrical. But on to my question: Given that the all the matter we see and think we understand in our daily lives appears to be a tiny 0.03% of the total, what effects might the insane amount of invisible stuff (neutrinos, dark energy, dark matter) be having on our lives? In other words, could there be any noticeable/measurable effects on everyday reality? What forms might this take?

  34. #34 CB
    July 20, 2012

    @ bobh:
    I think those are good questions! I can answer a couple: DE is theorized in a Relativistic universe, so it assumes a constant speed of light, and as a consequence of that a non-constant time scale. And new physics very much lies beyond discovering that the assumptions of Relativity are wrong. :)

    Standard candles aren’t really an ‘assumption’ on their own. They’re based on studying objects whose distances we can measure through other means and finding that they have observed properties that correlate very well with distance. The underlying assumption here is that the laws of physics are the same everywhere, so e.g. once you get outside of range for parralax measurements, Cephid variables don’t suddenly start behaving differently (but in such a way that it still appears to match up with supernova distance measurements) and so on.

    I think it would be fantastic if Ethan wrote about the Cosmic Distance Ladder. Assuming he hasn’t; a quick search didn’t turn anything up. It’s a pretty fascinating subject. To me anyway.

  35. #35 chelle
    Latveria
    July 20, 2012

    Wow et al.

    I’m not talking here about luminiferous ether.

    “Einstein proposed a definition of a new relativistic ether that can be expressed in the following short form:

    field gμν = ether.”

    A.Einstein, Letter to H. A. Lorentz, 17.06.1916, Einstein Archives, 16-453.

    “Thus, once again ,,empty” space appears as endowed with physical properties, i.e., no longer as physically empty, as seemed to be the case according to special relativity. One can thus say that the ether is resurrected in the general theory of relativity, though in a more sublimated form.”

    A. Einstein, Grundgedanken und Methoden der Relativitatstheorie in ihrer Entwicklung dargestellt, (Morgan Manuscript) Einstein Archives 2070.

  36. #36 Denier
    July 20, 2012

    My question is simple: If dark matter is real, why is it so uniform?

    When we look at alien solar systems, the matter halo surrounding the central star seems to come in all shapes and sizes. Some systems have huge planets orbiting close in, others don’t. We see from observations that halos of matter are not uniform.

    The bullet cluster lensing is often trotted out as proof of dark matter being separated from regular matter. If collisions separate dark from normal matter, then it would stand to reason that galaxies that had been through many mergers would have less dark matter than those who did not. Yet it is always the same halo of ~140 solar masses of dark matter per square parsec needed to get the rotation to work out right.

    While I have read several post on this blog that give explanations to many of the questions asked here in this thread, I haven’t seen this question addressed. Back in 2008 it was written:

    “MOND is far superior to all models of dark matter in predicting the observed rotation curves of galaxies.”
    -Ethan Siegel [1]

    There is no need to get into MOND, but if dark matter is the theory you are championing, I’d like to read your thoughts on how the current dark matter models incorporate these observations. If dark matter is really some sort of matter, why is it so uniform?

    [1] http://scienceblogs.com/startswithabang/2008/01/mond-vs-dark-matter.php

  37. #37 wow
    July 20, 2012

    I don’t think it is uniform. A uniform dark matter field would be grounds for considering it MOND rather than matter.

    At least, recently they have considered an inexplicable galactic lensing event to be evidence of a clump of dark matter. If this is the case, then not all the effecseen can be attributed to some variation in gravitational attraction.

  38. #38 wow
    July 20, 2012

    So call it what it is, then, chelle: vacuum of empty space.

    And it’s already included.

  39. #39 zeuxis
    United States
    July 20, 2012

    Why does the first chart with the yellow, green, blue and red possibilities seem to “privilege” the current time period as the convergence point of the fate of the fate of the universe? Isn’t that in and of itself suspicious?

  40. #40 chelle
    July 20, 2012

    Wow,

    I find your response a bit strange, I just quoted Einstein saying:

    “… no longer as physically empty, as seemed to be the case according to special relativity.

    … and you say:

    “So call it what it is, then, chelle: vacuum of empty space.”

    … while the ‘vacuum’ is described as:

    “In quantum field theory, the vacuum state (also called the vacuum) is the quantum state with the lowest possible energy. Generally, it contains no physical particles.http://en.wikipedia.org/wiki/Vacuum_state

    And I’ll add an extra quote to that:

    “According to the general theory of relativity, space without ether is unthinkable; for in such space, not only would there be no propagation of light, but also no possibility of existence for standards of space and time (measuring rods and clocks), nor therefore any space-time intervals in the physical sense.”

    A. Einstein, Aether und Relativitaetstheorie, Berlin: Verlag von J. Springer, 1920.

  41. #41 Cleon Teunissen
    July 20, 2012

    I wonder, how did the name ‘dark energy’ become a common expression?

    quoting from 2008:
    http://scienceblogs.com/startswithabang/2008/04/09/what-is-dark-energy/

    “if the Universe were full of a new type of energy that had a repulsive pressure, it would cause the expansion rate to speed up again.”

    Recapitulating:
    In a universe with critical density you expect a particular profile in decrease of rate of expansion. The expansion never stops (if it would the universe would recollapse), but with critical density the rate of expansion goes to zero.

    The observations indicate an anomaly in the decrease of rate of expansion. There is less decrease than expected.

    I’d like to use an acronym for that: CERA
    Cosmic Expansion Rate Anomaly.

    (For comparison: the term ‘Pioneer anomaly'; as long as you don’t know the cause you refer to it as an anomaly.)

    The word ‘energy’ is a key word in physics. Why is CERA referred to with the expression ‘Dark Energy’? It’s unknown whether there is a relation with the concept of Energy.

  42. #42 dr von sickenstein
    Weymouth MA USA
    July 20, 2012

    When black holes and gamma-ray bursts shred baryonic matter and fling it into the void of inter-galactic space, couldn’t those sub-atomic particles still hold gravitational sway, considering they hold mass?

    I’ve also seen experiments using magnets in space. Can’t magnetism account for some of our galaxy’s centripetal motion – which should alter the over-simplified equations of gravitational influence?

  43. #43 CB
    July 20, 2012

    @Denier
    “My question is simple: If dark matter is real, why is it so uniform? If collisions separate dark from normal matter, then it would stand to reason that galaxies that had been through many mergers would have less dark matter than those who did not.”

    Remember that DM is still affected by gravity so unless the visible matter is slowed so much the DM is at escape velocity relative to it, it’s not actually going to leave and the separation seen in the Bullet Cluster is transient. So it seems that multiple mergers would result in a could of dark matter around and extending well beyond the visible galaxy. This is what simulation show, so I trust the math works out.

    @ chelle:

    The Cosmological Constant is indeed a possible explanation for Dark Energy — Einstein’s greatest blunder may end up being a triumph. Though the real blunder as it were was assuming the universe was static, and that remains invalid.

    And while it may be tempting to call the Cosmological Constant “Ether”, it doesn’t illuminate and rather just confuses. The Luminiferous Aether was proposed to be a fixed reference frame where Maxwell’s Laws applied, but it is the fundamental assumption of Relativity that this is not true and Maxwell’s laws apply in every reference frame. So the two things are diametrically opposed.

    There’s multiple senses of “physically empty” in use here; don’t confuse them. Einstein didn’t mention any particles. If the lowest energy state of the vacuum is non-zero, then it would still be empty of real particles (though still teeming with virtual ones), but would have energy and thus in a different sense is not empty.

    @ Cleon Teunissen

    “There is less decrease [in the rate of expansion] than expected” is a very odd way of saying that “the rate of expansion is increasing“.

    And yes “energy” is a well defined concept in physics, and it is because of this that we can say with assurance that accerelating universal expansion necessarily has a relationship with some kind of energy.

  44. #44 CB
    July 20, 2012

    @ Zeuxis
    “Why does the first chart with the yellow, green, blue and red possibilities seem to “privilege” the current time period as the convergence point of the fate of the fate of the universe?”

    Because the universe is the size it is now, right now. So whatever model you have for the expansion rate of the universe and the expected sizes for past and future, at time now the universe must be the size it is now. See? :)

    Note that one thing that changes is how long before now the universe was size 0 — as in how old the universe is, and when “now” is relative to the age of the universe. If you re-drew the graph so all lines started at size=0 at time=0, then the points where size=1 (size of universe ‘now’) would be at different times and there’d be no convergence. Hope that helps.

  45. #45 Rick
    Ogden, Iowa
    July 20, 2012

    Could the acceleration we see simply be a massive gravity wave from the big bang rippling through space time?

  46. #46 Alan L.
    July 20, 2012

    Modifying option 3 of Ethan’s post which reads:

    Could perhaps the supernovae have been the same, but the environments in which they detonated were different, giving an intrinsically less bright explosion?

    To:

    Option 3.1
    Could perhaps the supernovae have been the same, but the environment through which light travelled from the positions in which the supernovae detonated be different to what we currently believe thereby producing the illusion of what appears to be an intrinsically less bright explosion?

    In a Hypothetical Parallel Universe (HPU) where the green or blue line is the ‘true’ line and the HPU is in near perfect balance, what special property would particles of Invisible Dark Matter that permeate the HPU be required to have in that universe to duplicate the effect that we observe in our universe (red line).

  47. #47 Sly Philosopher
    California, USA, Universe
    July 21, 2012

    Please read about the “Great Attractor.” Several articles have been written concerning the “great attractor” where it is shown that a large portion of the universe in the vicinity of our galaxy is not, I repeat, is not expanding but in fact is condensing! The red-shift spectral evidence (presented in this article) indicating an accelerating expansion of the universe with distance can just as easily be explained by the gravitational red-shift phenomenon predicted by the GENERAL THEORY OF RELATIVITY if one applies this theory to our entire universe. However, I have found only a few astronomers and astrophysicists who are supporting this alternative hypothesis in accordance with the General Theory of Relativity. Too bad Einstein isn’t still alive.

  48. #48 chelle
    July 21, 2012

    CB,

    “Though the real blunder as it were was assuming the universe was static, and that remains invalid.”

    This is what I challenged, saying that us influence the space that surrounds us, makes it look as if galaxies are moving further and further away, while it might be the input our energy into space that is moving further and further away. (Mr. White’s principle)

    “And while it may be tempting to call the Cosmological Constant “Ether”, it doesn’t illuminate and rather just confuses.

    I wrote in a previous comment that it is not luminiferous Ether, so calling it just ‘Aether’ makes perfect sense, perhaps even better than Dark Matter, there is a conceptual meaning to Aether, as a substance through which particles move, just like a flock of fish swims in the seawater that makes up an ocean.

    “The Luminiferous Aether was proposed to be a fixed reference frame where Maxwell’s Laws applied, but it is the fundamental assumption of Relativity that this is not true …”

    Yes that of Special Relativity, but not General Relativity, here’s Einstein’s quote again that I added earlier:

    “Thus, once again ,,empty” space appears as endowed with physical properties, i.e., no longer as physically empty, as seemed to be the case according to special relativity. One can thus say that the ether is resurrected in the general theory of relativity, though in a more sublimated form.”

    “… and Maxwell’s laws apply in every reference frame. So the two things are diametrically opposed.”

    Did you know that Maxwell reintroduced an Aether model to generate his formulae at a time that Aether was abolished after Newtons ‘Corpuscular theory of light’.

    “There’s multiple senses of “physically empty” in use here; don’t confuse them. Einstein didn’t mention any particles. If the lowest energy state of the vacuum is non-zero, then it would still be empty of real particles (though still teeming with virtual ones), but would have energy and thus in a different sense is not empty.”

    But what do we learn in practice, that empty space or the Vacuum is full of physical matter, hence “One does not simply “believe” in Dark Energy…”

  49. #49 Cleon Teunissen
    July 21, 2012

    @CB (comment July 20, 5:51 pm)

    Let me again recapitulate what Ethan has written earlier about the expansion rate.

    The standard unit to express the expansion rate is the Hubble constant. The Hubble constant is not about how specific pairs of galaxies move relative to each other. The Hubble constant goes back to Hubble’s law: there is a ratio of receding speed and distance in parsecs.

    Quoting Ethan, writing about the Universe-with-critical-mass scenario:
    http://scienceblogs.com/startswithabang/2008/03/12/the-universe-is-accelerating/

    “But what this means is that the Hubble constant (which is 71 km/s/Mpc today), which would normally asymptote to zero as all the matter in the Universe expands away, actually asymptotes to about 60 km/s/Mpc.
    [...]
    the Universe will just keep on expanding and expanding, without slowing down. This is an acceleration relative to a Universe with no dark energy, but the expansion rate isn’t speeding up; it just isn’t slowing down.”

    So that’s the picture if you think of it in terms of the expansion rate, expressed as the Hubble constant.

    What if you consider a specific pair of galaxies? The Hubble constant is velocity per megaparsec. An object about 1 megaparsec away should move away from us at 70 km/s, one 10 megaparsecs distant moves away from us at 700 km/s, etc.
    In an expanding universe a galaxy that is 1 megaparsec away now will be 10 megaparsecs away at some point in the future. And then you apply Hubble’s law.

  50. #50 Wow
    July 21, 2012

    Chelle, you’re tiresome now.

    You quotemine and reify concepts to peddle some assinine contrary statement into some sort of mystical deep significance.

    Such significance is imaginary in your head and you are not a budding einstein with deep insights but an internet gallilleo who is a poster child for the DK effect.

  51. #51 Wow
    July 21, 2012

    Oh, chelle, your response to me of “not luminouus aether” was about my response to Mu’s post.

    Seems like you’re posing under different names.

    Why?

  52. #52 chelle
    July 21, 2012

    “Seems like you’re posing under different names. Why?”

    Because you are paranoid.

  53. #53 Norma Parfitt
    July 21, 2012

    My question is: Why should I care whether Dark Energy exists or whether it’s just an intellectual exercise?????
    aka ‘What’s in it for me?’

  54. #54 chelle
    July 21, 2012

    “Why should I care whether Dark Energy exists or whether it’s just an intellectual exercise?”

    Awareness about what makes up the ‘vacuum’ gives us a better understanding of what we physically can do within a vacuum.

  55. #55 David Gold
    Torquay, UK
    July 21, 2012

    An attempt has been made to explain Dark Energy in a theoretical paper, ‘Theoretical Principle Model of Forces’, and can be found at http://scienceau.com. Dark Energy appears as a missing force in a previously unrealised symmetry of fundamental forces. Therefore, Dark Energy is likely to be a fundamental force of nature; a force that only interacts (as a by-product) via the Weak Nuclear Force and is not directly experienced on Earth.

    As a force Dark Energy, responsible for the current accelerating expansion of our universe, can also manifest in another unrealised phenomenon involving the Gravitational force in an ‘self-regulatory process’; a counterbalancing process between the two forces, which would appear to be a critical aspect in the formation of galaxies. It is concluded that Dark Energy’s involvement in additional self-regulatory processes and the role played in the accelerating expansion appear essential in the far future as to the consequential fate and important purposefulness of our universe.

    Ethan, like very much the way you present a subject – stimulating and makes for excellent teaching.

  56. #56 bobh
    United States
    July 21, 2012

    @CB (wish comments were numbered) I wasn’t referring to time scales as different in the relativistic sense, or at least I didn’t think I was. velocities are dx/dt, I was thinking more along the line of the definition of dt, i.e. that the time dimension of spacetime grows or shrinks.

  57. #57 CB
    July 21, 2012

    @ chelle
    - “The Luminiferous Aether was proposed to be a fixed reference frame where Maxwell’s Laws applied, but it is the fundamental assumption of Relativity that this is not true …”

    Yes that of Special Relativity, but not General Relativity,

    BWA HA HA! You think it’s not a fundamental assumption of GR that there is no preferred reference frame, and Maxwell’s laws giving constant c applies in every reference frame? Congrats on demostrating you have no idea what you’re talking about! For your edification, GR actually took that assumption even farther, taking the special principle of relativity and expanding it to the general principle of relativity. The assumption that the relativity principle holds is so basic, so fundamental, that they named the Theory of Relativity after it!

    Also you seem to be getting Dark Matter and Dark Energy confused.

    You use Ethan’s “one doesn’t simply believe in Dark Energy” quote when saying we’ve learned that the vacuum is full of physical matter when that is completely untrue. There is no reason to believe Dark Energy is a form of matter whatsoever and that has nothing to do with Ethan’s belief in it or the evidence for it.

    And I know you’re not talking about the “luminiferous aether”, but rather referring to the Cosmological Constant as “Aether”. Which you’re welcome to do, but realize:
    1) It’s confusing because when you say “Aether” anyone listening will assume this is shorthand for “luminiferous aether” so I hope you really like repeating “not luminiferous” all the time.
    2) It doesn’t illuminate the subject at all (c what i did thar). Because it isn’t a “substance” as that word usually means (i.e. physical matter), it isn’t a “medium” like the ocean in any meaningful sense. So using that connotation of “Aether” when there’s no reason to believe it has any invitation to reality does nothing but invite “argument by analogy” which is everyone knows is a form of fraud.

    But also your favorite thing in the world. So I won’t begrudge you its use. I just hope you’ll understand why this use of “Aether” is at best nothing more than a name, and at worst a hindrance to communication and understand.

  58. #58 CB
    July 21, 2012

    @ Clean

    Ah, fair enough. Hopefully you can still see how “less deceleration” is still an acceleration, and how energy much then neccessarily be involved.

    The Pioneer Anomaly was evidenced by a deceleration. And therefore also necessarily involved energy. And as it turns out this was true, it was the probe’s heat energy and a preferred direction for its emission that was the cause of the anomaly.

  59. #59 Wow
    July 21, 2012

    Sorry, chelle, your posting under two names is the consequential conclusion of your posts.

    Paranoia would have nothing to do with that either way.

    Seems like among the many things you don’t know includes the meaning of paranoia.

    Silly little girl.

  60. #60 Ultrarockrunner
    NY
    July 21, 2012

    If we turned out all the lights (aka stars), would we see it?

  61. #61 chelle
    July 21, 2012

    - “BWA HA HA! You think it’s not a fundamental assumption of GR that there is no preferred reference frame …”

    You are right, I was wrong with my reply. I was focussing on the difference between space without matter and without electromagnetic field in SR, and the fact that space in GR has physical properties like an ether whose state varies continuously from point to point.

    Also you seem to be getting Dark Matter and Dark Energy confused.

    I’m not confused, but I have been mixing the two, we can think of a field that is physical state of space, and Dark Matter and Dark Energy might be manifestations of the same dark ‘thing’. I’m only making the suggestion that it could be an Aether.

    And I know you’re not talking about the “luminiferous aether”, but rather referring to the Cosmological Constant as “Aether”. Which you’re welcome to do, but realize:
    1) It’s confusing because when you say “Aether” anyone listening will assume this is shorthand for “luminiferous aether” so I hope you really like repeating “not luminiferous” all the time.

    That’s a fair argument, but one could also add to the fact that one hasn’t got to repeat that the ‘Vacuum’ is ‘not empty’.

    2) It doesn’t illuminate the subject at all (c what i did there).

    nice one :)

    Because it isn’t a “substance” as that word usually means (i.e. physical matter), it isn’t a “medium” like the ocean in any meaningful sense. So using that connotation of “Aether” when there’s no reason to believe it has any invitation to reality does nothing but invite “argument by analogy” which is everyone knows is a form of fraud.

    That’s true, but at the end of the day we are talking here about ‘Space’ being an entity, and it that case an ocean full of water is figurally speaking closer to the truth, than an empty space with nothing in it (Vacuum).

  62. #62 Cleon Teunissen
    July 21, 2012

    CB wrote:
    > Hopefully you can still see how “less
    > deceleration” is still an acceleration

    Let me put it like this: “Is the pope catholic?”

    Anyway,
    it may well be that the area of cosmic expansion rate anomaly research is still rapidly changing. Eric V. Linder assesses in his 2008 review article “Mapping the cosmological expansion” that extrapolations to the future are to a large extent speculation. Different theories of the cause of the anomaly lead to different extrapolations. Possibly in some theories the Hubble constant goes on to increase again, I don’t know.

  63. #63 dorght
    July 21, 2012

    Couldn’t physicists come up with a better name then ‘dark energy’? I mean come on, how is one suppose to evoke the mystical side of physics, write books, do the talk show circuit and become wealthy when your saddled with the pedestrian phrase ‘dark energy’? Now Quantum there’s a word. No fighting people’s prior knowledge of the words ‘dark’ and ‘energy’ with Quantum. With Quantum people are ready to bow down in their ignorance to anyone who purports an understanding of it. ‘Dark energy’ that’s the best the current crop of scientists could come up with? Just more evidence of a vast scientific conspiracy against free market woo peddlers.

  64. #64 kita
    July 21, 2012

    If only we can capture dark matter.

  65. #65 lee a. pseudogrammaton
    tallahassee, fl.
    July 22, 2012

    Any possibility that DE is related to ‘weak gravity?’

  66. #66 Marcus Ranum
    USA
    July 22, 2012

    “Dark energy” sounds so delightfully Nietszchean!

  67. #67 OKThen
    July 22, 2012

    It’s best to ignore Chelle; he wraps famous quotes in anti-science nonsense.

  68. #68 chelle
    July 22, 2012

    > “It’s best to ignore Chelle;”

    Thanks for the info.

    > “he wraps famous quotes in anti-science nonsense.”

    The quotes I use here are ‘not’ famous, because some like to consider SR & GR as the end of the Aether, while in practice it was clearly not the case for Dr. Einstein, that’s why I’m posting them. You could learn something here, but your witch-hunt makes you apparently too blind to see.

  69. #69 Stellar Ash
    July 22, 2012

    Assuming that dark energy is real and not a modern day ether, the only other force that we know of that gets stronger over distance is the strong force.

    Are there any similarities between the equations of the strong force & what is known of the equations that model dark energy?

    These may be dumb questions: I know enough to know that I just don’t know enough.

    Could the separation of matter over universal distances be creating dark energy that condenses as ‘space’ in a manner similar to how pulling quarks apart causes an energy increase that eventually causes more quarks to form?

  70. #70 Usually Anon
    July 22, 2012

    How uniform can we say dark energy is? To rephrase my question, how much variance in the rate of expansion of volumes of space is consistent with our observations?

    Are there observations we could make which would be sensitive to changing strengths of dark energy and do we have the instruments to measure them?

  71. #71 Momentus
    Northampton UK
    July 23, 2012

    Dark Energy and Dark Matter are terms used to “explain” observed motions.
    Therefore it is “Dark Motion” which is truly the inexplicable phenomenon.

    The solution to Dark Motion is a demonstrable change in Newtonian Dynamics. There are equal and opposite forces, not equal and opposite actions.

    Dark Motion can be reproduced by simple experiment. This post http://www.gyroscopes.org/forum/questions.asp?id=1464 gives details of a simple thought experiment.

    I did “enjoy the read”, your evidence is both compelling and easy to follow.
    If you can overcome the gyrophobic nature of mainstream science, then my thought experiment is a prime example of dinosaur footprints.

    I hope you have fun at the weekend and that you take my post as a topic for discussion.

  72. #72 Wow
    July 23, 2012

    Momentus, a thought experment isn’t an experiment.

  73. #73 Momentus
    July 23, 2012

    @wow
    (Momentus, a thought experment isn’t an experiment.)

    Good excuse not to exercise the brain then.

    What I had in mind was

    “A thought experiment or Gedankenexperiment considers some hypothesis, theory, or principle for the purpose of thinking through its consequences. Given the structure of the experiment, it may or may not be possible to actually perform it, and, in the case that it is possible for it to be performed, there need be no intention of any kind to actually perform the experiment in question. The common goal of a thought experiment is to explore the potential consequences of the principle in question.”

    The Wiki definition

    Do first try to solve the puzzle and then feel free to put down the newbie.

  74. #74 chelle
    July 23, 2012

    Momentus,

    Dark Motion, nice :mrgreen:

    1) Do you know that: “Much of the evidence for dark matter comes from the study of the motions of galaxies.”http://en.wikipedia.org/wiki/Dark_matter#Observational_evidence

    2) I’ve checked your post, and an object that goes from one orbit to a faster smaller orbit needs to slow down, instead of “speed up, to conserve momentum”. You might want to check Kepler’s 3rd ‘harmonic’ law and the structure of the rings of Saturn.

    3) There is nothing wrong with a thought experiment, but a drawing, or two, might be more helpful to understand what you’re talking about.

  75. #75 Wow
    July 23, 2012

    Good excuse for getting it wrong, momentus.

    Oh no. It wasn’t.

    You should not have said your hypothesis was testable by experiment. That means something very specific.

    And the assertion you make about the gyroscope does not follow on from your thoughts on it. They acy very unlike your assertion wants them to do.

  76. #76 chelle
    July 24, 2012

    Momentus, did you know that there is also a concept called ‘Dark Fluid’, and other idea but unrelated to DE & DM called ‘Dark Flow’.

    http://en.wikipedia.org/wiki/Dark_fluid
    (http://en.wikipedia.org/wiki/Dark_flow)

  77. #77 Momentus
    Northampton UK
    July 24, 2012

    @chelle

    Conical_pendulum

    Newton, Hooke and Kepler all experimented with conical pendulums, as there are similarities with planetary orbits.

    With a pendulum, shortening the length of the cord reduces the period, the time for one rotation. The speed of rotation ω increases.

    The tangential velocity remains constant. Momentum remains constant.

    If you have ever played “swingball” you will have seen the speed of rotation dramatically increase if the cord wraps around the pole!!.

    I will pass on Saturn’s rings. Far too complicated and not strictly relevant to the simplicity of the pendulum thought experiment.

    It is the comparison of the difference in behaviour between the two systems which is important.

  78. #78 Momentus
    Northampton UK
    July 24, 2012

    OOPs Conical_pendulum lost its hyperlink should be:-
    http://en.wikipedia.org/wiki/Conical_pendulum

  79. #79 Momentus
    July 24, 2012

    wow

    Off to a bad start and getting worse!

    “Dark Motion can be reproduced by simple experiment.” A statement of fact. I have done several experiments which show this. No point in giving details.

    “A simple thought experiment” Separate from the above. Written in all innocence. No intent to deceive.

    “…They acy very unlike….”.
    There are many, many videos of gyroscopes suspended from flexible cords on the internet. All show that the speed of rotation about a vertical axis is governed by precession. That is impossible behaviour for a suspended mass. You either have a sufficient understanding of conical pendulums to appreciate this, or you do not.

  80. #80 chelle
    July 24, 2012

    > “The speed of rotation ω increases.”

    It’s not because the angular velocity increases that the object speeds up. If it speeds up, it would go into a wider orbit. You might be overlooking the centripetal force, also think of how a ‘Wall of Death’ stunt rider needs to have a higher speed to ride it, the wider the wall the more speed he’ll need.

    Regarding a ‘swing-ball’ you could google the ‘Tetherball Problem’ and use formulas and some drawings to express what you mean with your thought experiment because it is unclear.

  81. #81 Wow
    July 24, 2012

    ““Dark Motion can be reproduced by simple experiment.” A statement of fact”

    A simple statement of fallacy.

    Dark Motion cannot be reproduced by a simple experiment. Or indeed any experiment undertaken to date. This is why your assertion remains with the hidden “thought”.

    Thought experiment != Experiment.

    “There are many, many videos of gyroscopes suspended from flexible cords on the internet.”

    Indeed there are.

    But they don’t act like you say they do in your THOUGHT experiment.

  82. #82 Wow
    July 24, 2012

    “All show that the speed of rotation about a vertical axis is governed by precession. That is impossible behaviour for a suspended mass.”

    This would be because a non-rotating suspended mass doesn’t rotate. Making precession undefined.

    Rather like proclaiming “Flights of birds show a marked correlation between wingbeat and total weight, impossible for ruminant bovines to do!”.

    You also have severe problems with nomenclature.

    Science requires precisionist language. Yours is all over the place.

  83. #83 Wow
    July 24, 2012

    “2) I’ve checked your post, and an object that goes from one orbit to a faster smaller orbit needs to slow down, instead of “speed up, to conserve momentum””

    Momentus, here’s another example of your inaccuracies.

    Angular momentum or linear momentum?

    Because you need to reduce your speed at one orbit to de-orbit to a lower one.

    If you were to try to speed up you’d go to a more elliptical and higher orbit.

    Even though the smaller orbit completes quicker, you have to slow down to get to it.

  84. #84 CB
    July 25, 2012

    Oh man I just read their blog entry – HA HA HA! Aside from the amusement of a “thought” experiment where the result is simply made up (conical gyroscopic pendulums do not behave that way), the real beauty was at the end, where I missed it at first.

    They bring up the Pioneer Anomaly as something normal physics can’t explain but their theory can — CLASSIC crackpottery.

    Apparently they haven’t gotten the memo that the Pioneer Anomaly has been explained by nothing more exotic than the probe’s own heat emissions.

    But even before it was explained (and this was the most probable explanation for a long time), it’s still a hilarious example of crackpottery. Because the crackpot’s go-to answer for any mystery is “all of physics is wrong and I am right!”, not “the model to which we were applying the known laws of physics was not a sufficiently good approximation”. Because where’s the fun in that?

    Anyway, I’ve recently been wondering how crackpots would deal with Pioneer. I had guessed they’d simply delete it from their list of things that “prove” they are correct (since if their theory did predict the anomalous acceleration, but now the acceleration is explained by existing theory, then that means the extra acceleration predicted by their theory doesn’t exist and their theory is falsified).

    I never imagined they’d just blithely keep on referring to it as if it still proved mainstream physics was wrong and they were right! That’s so much better than I had hoped!

  85. #85 Momentus
    Northampton UK
    July 26, 2012

    http://techtv.mit.edu/videos/717-mit-physics-demo-bicycle-wheel-gyroscope

    A typical example of a gyroscope precessing about a vertical axis.
    The time for one complete revolution is determined by the precession, it is not related in any way to the length of the cord.

    That is how a suspended gyroscope behaves.

    These are dinosaur droppings, steaming and fresh.

  86. #86 Wow
    July 26, 2012

    And we know what gyroscopes do, Momentus.

    And we know they precess.

    And we know that period of precession is not related to the length of something that is tied to the end of the gyroscope axis.

    Do YOU know what that period of precession is related to?

  87. #87 CB
    July 26, 2012

    Oh goodness. I thought you were trying to set up a situation analagous to a conical pendulum only with a gyroscopic bob similar to how a planet orbits a star but also spins and precesses. The only “orbit” in that video is the precession itself! Set the whole wheel assembly swinging in a circle so the end of the string is tracing a circular orbit and you’ll find the period of that orbit does indeed depend on the radius -and the ang. moment. of the gyroscope.

    Both situations are explainable with Newtonian mechanics. The only thing “dark” about this motion is your comprehension.

    P.S. Pioneer anomaly, LOL.

  88. #88 CB
    July 26, 2012

    P.P.S. “These are dinosaur droppings, steaming and fresh” is the perfect description… just not in the way you meant. I’m reminded of a similar quote from Jurrasic Park.

  89. #89 Desiree'
    http://msdisarray.wordpress.com
    July 26, 2012

    LOVE the LOTR reference in the title!! :):)

  90. #90 Michael Mozina
    Mt. Shasta, CA
    July 26, 2012

    FYI, plasma redshift, a “prediction” of many Plasma Cosmology/Electric Universe models has now been confirmed in the lab. This laboratory observation not only eliminates the need for dark energy, it does away with the concept of expansion.

    http://www.sciencedirect.com/science/article/pii/S0030402608000089

    These results do fit with a number of “tired light” proposals including one by Lyndon Ashmore who cites that Chen paper and explains how it relates to his ‘New Tired Light’ theory and cosmology.
    http://vixra.org/pdf/1105.0010v1.pdf

    Herman Holushko has published C# code using these plasma redshift/tired light models to explain why light of various wavelengths is broadened and why they arrive at different times.

    http://vixra.org/pdf/1203.0062v1.pdf

    The ‘prediction’ that wavelengths travel at different speeds though the plasmas of spacetime have also been confirmed in recent years.

    http://www.news.ucdavis.edu/search/news_detail.lasso?id=8364

  91. #91 Momentus
    July 27, 2012

    Now you seemed have grasped the very basic nature of the thought experiment, a conical pendulum and a precessing gyroscope are moving around a vertical axis at the same speed at the same radius, and so have the same tangential velocity, and the same momentum.

    Changing the length of the cord changes the external centripetal force acting on the conical pendulum.

    What centripetal force is acting on the gyroscope pendulum? Why does it not change?

  92. #92 Chelle
    July 27, 2012

    Michael Mozina,

    The presented ‘Tired Light’ hypothesis is not a good one, and certainly not the interaction with ‘visible’ matter such as plasma. One has to look for the interaction with what we can’t see, that is Dark Matter and Dark Energy that fill up the Empty Vacuum and that makes up the Aether. Imho the Energy that we put out into space has an effect on DM and DE and so indirectly on the light that is being Redshifted, you are overlooking here one step to get this idea to work, and there remains a great ‘IF’ it would work.

  93. #93 Chelle
    July 27, 2012

    Momentus,

    Like I said before; draw it out what it is that you want to make clear, because it still sounds like you are comparing apples and oranges.

  94. #94 Wow
    July 27, 2012

    You’ve been warned about using “Aether” because you have no clue what you’re talking about and using it, neither does anyone else.

  95. #95 Wow
    July 27, 2012

    “Changing the length of the cord changes the external centripetal force acting on the conical pendulum.”

    Fail: Centripetal ACCELERATION. The force is CENTRFUGAL.

    “What centripetal force is acting on the gyroscope pendulum? Why does it not change?”

    Fail2: No centripetal force is acting on the gyroscope. Since it doesn’t exist before, doesn’t exist after, it didn’t change.

    PS Still didn’t answer the question. Did you. What does the period of precession depend upon?

  96. #96 Chelle
    July 27, 2012

    Wow,

    Ethan sees it as a ‘fluid’, and Einstein proposed an Ether, what you think is your opinion, thanks for sharing.

  97. #97 Wow
    July 27, 2012

    And none of that means “Aether”. Why not call if “Cauliflower” if you’re going to repurpose names to mean what you mean them to mean?

    Because it’s either make it obvious you’re repurposing words or put a disclaimer at the bottom of every post you have that uses words with specific meanings that you mean, even if nobody else uses them that way, to define what you mean by that word.

    At least with using “Cauliflower”, people will know you’re using a non-standard definition you’ve made up.

  98. #98 Chelle
    July 27, 2012

    Einstein didn’t use ‘Cauliflower’ he used Aether, I gave you some references that you can check. Ethan spoke of a ‘fluid’ that “permeates throughout all of space with a positive energy density and a negative, outward-pushing pressure.” that YOU think is NOT right. He doesn’t see it as an Ether because of the “expansion rate of the Universe”, that is fine by me, we may differ, and one needs to bring up proof to contest what he is saying, I fully agree, and the proof of ‘Tired Light’ hypothesis is not good enough, although I see some merit in this idea. If you don’t like it, than that is fine, I don’t say that Aether is a fact, but one should be free to discuss it without some grumpy individual waving around with warnings.

  99. #99 Wow
    July 27, 2012

    OK, here’s the illustration of your problem:

    The Aether was disproven by the Michelson-Morely experiment.

  100. #100 Chelle
    July 27, 2012

    Wow,

    Look at your post in this thread at July 20, 7:11 am, and look at my reply a few hours later (9:36 am). It looks like your memory is no longer any good. Take care of what’s left.

  101. #101 Wow
    July 27, 2012

    Nope, you’re the one who forgot about it.

    Or you’re deliberately abusing the words to fake your ramblings as deep-meaning philosophy rather than the load of codswallop
    it really is.

  102. #102 Chelle
    July 27, 2012

    Get a life.

  103. [...] is put to the test. Such skepticism isn’t due to hostility, it’s just how science works.Ethan Siegel provides a real-world example — a personal testimony — of what it means for a scientist to encounter startling, [...]

  104. #104 Doug Sweetser
    Acton, MA
    July 30, 2012

    Does anyone know the value of this odd acceleration is in terms of g, the good old apple falling to the ground, 9.8 m/s^2?

    This vital detail is almost always skipped. I read that Milgrom of MOND fame calculated it to be on the order of 10^-10 g (any real citation to the value would be appreciated).

    We have multiple problems on the super-weenie scale of the super weakest force in Nature. I predict a fix will not require a crap ton of new stuff that doesn’t fit into the standard model. I do agree we have to fix this problem, but it will be a math fix.

  105. #105 Wow
    July 31, 2012

    I have a life, chelle. And intelligence, memory, self-respect and honesty. Please find some of these for yourself.

  106. #106 Chelle
    July 31, 2012

    > “I have a life.”

    Yeah sure, that of a ‘boboon’ who starts to insult others and manipulate words when something isn’t in line with his own bonehead ideas, who needs to bring up ‘again’ the Michelson-Morley experiment, after it has been dismissed because Einstein spoke of a NEW Aether, or he needs to throw around a warning, or a cauliflower … Yep, all the stuff that an aggravated alpha monkey does when opposed, but not someone who lives an honest an calm observing scientific life. 

  107. #107 Wow
    July 31, 2012

    You, on the other hand, seem to be infantile.

    Maybe one day you’ll become at least semi-adult.

  108. #108 Wow
    July 31, 2012

    PS you again seem to be missing the point.

    The point is that the aether is taken to mean the medium through which light travelled as presupposed by the Victorian scientists and disproven by the Michelson Morley experiment.

    The use of aether in other contexts, as has been pointed out to you several times before, is conducive to misinterpretation.

    However you insist on using it because you wish to pretend you have some “special insight” (as opposed to special needs) into the science that nobody else has.

    As long as you want to use aether rather than vacuum, I’ll continue to point out that the aether is disproven by the Michelson-Morley experiment.

  109. #109 chelle
    July 31, 2012

    “As long as you want to use aether rather than vacuum, I’ll continue to point out …”

    Wow, you could do this, but you have to know that is you, and only you, who just is not getting it. Check this article in National Geographic, and check the ‘continued’ page where a bunch of theoretical physicists understood that a NEW Ether is not the same as a Luminiferous Ether:

    Dark Matter’s Rival: Ether Theory Challenges “Invisible Mass
    http://news.nationalgeographic.com/news/2006/09/060908-dark-matter.html

  110. #110 Wow
    July 31, 2012

    No, not could.

    Will.

    And what are you trying to prove with that link? That you’re no more scientifically literate than a journalist?

  111. #111 Chelle
    July 31, 2012

    > “No, not could. Will.”

    See, that is your problem, you are unable compromise. There is something in you that prevents you to adjust your (tunnel) vision. Your refusal to learn something ‘new’ holds you back to evolve from the ‘baboon’ that you are, onto the level of a homo sapien. It is a pitty.

  112. #112 Wow
    July 31, 2012

    No, not my problem.

    Yours.

  113. #113 Wow
    July 31, 2012

    Why not compromise and use the word “Chocolate” instead? Then neither have gotten what they wanted, which is fair, right?

  114. #114 Chelle
    July 31, 2012

    It is not about me versus you, and us finding a compromis between the two of us, if that would be the case, than sure, I wouldn’t mind calling it ‘chocolate’. The fact of the matter is, that everybody compromises that there could be a NEW Aether. I gave you references of Einstein who proposed an NEW Aether, there is that other more recent theoretical physicist in the National Geographical article who proposed a NEW Aether and who talks with his peers about a NEW Aether. There is only one person who can’t accept it, and who rather calls it ‘chocolate’ and that is you, dear Wow.

  115. #115 chelle
    Latveria
    August 3, 2012

    Wow,

    > “Why not compromise and use the word “Chocolate” instead?

    FYI, some words from a professor of physics at Cornell University:

    “In 1964, Higgs discovered a loophole that allowed him to propose a very special type of aether that might exist without contradicting Einstein’s relativity. This daring assumption lead to a simple resolution of the puzzle of particle masses: fundamentally all particles are massless, as the standard model predicts; however, their interaction with the all-penetrating Higgs aether slows down their motion, making them effectively appear as if they have mass. This is similar to a ping-pong ball appearing very heavy when dragged through honey — the interaction with the medium creates an apparent mass. This Higgs aether is supposed to be everywhere around us — a very bold prediction at the time.”
    http://www.stargazette.com/article/20120713/VIEWPOINTS02/207130302

  116. #116 Wow
    August 3, 2012

    That’s not an answer to the question given, chelle.

  117. #117 Chelle
    August 3, 2012

    Wow,

    I just thought it was funny because he uses ‘honey’ as a metaphor for the Aether, while you thought of it as a chocolate liquid, that is also sweet. :)

  118. #118 Wow
    August 3, 2012

    You’re making no sense.

    You quote a question of mine, don’t answer it and when this is pointed out go and segue into some bollocks about what you thought was funny about using the word “honey”.

  119. #119 Chelle
    August 3, 2012

    Ok, maybe my answer didn’t answer your question, but both you guys spoke of a liquid sweet in relation to the Aether, and I just thought it was a funny case of happenstance. Well if you don’t find it funny than that’s alright, jokes don’t always make a lot of sense, my bad if you didn’t got it, sorry.

  120. #120 OKThen
    Dark Chocolate
    August 3, 2012

    The idea: “Dark Matter and Dark Energy would be no other than… Aether.” Surely DE + DM must= something

    But naming is important, consider:
    Dark Energy, Dark Matter, Dark Flow, Dark Fluid, Dark Motion, why not????
    DARK CHOCOLATE

    Dark energy + Dark matter = Dark Chocolate.
    Dark Chocolate is a good name; but It is the idea that matters.

    Does this Dark Chocolate have any physical significance. Hard to tell; but a quick search reveals. Aha!!

    Hot off the press Aug 2, 2012
    Generalized models of unification of dark matter and dark energy http://arxiv.org/pdf/1208.0449v1.pdf
    “The idea that both dark matter and dark energy are actually the manifestations of a single dark component is both natural and appealing… Another approach to models of DM-DE unification that avoid the speed of sound problem are purely kinetic k-essence models and tachyon models… The equation of state of a barotropic cosmic fluid can in general be written as an implicitly defined relation between the fluid pressure p and its energy density ρ… we focus on finding the effective description of the cosmic dynamics with the cosmic fluid defined by in terms of a minimally coupled scalar field ϕ with a potential V (ϕ)… We restrict our analysis to the spatially flat Robertson-Walker metric motivated by the inflationary expansion and data on CMB anisotropies. Furthermore, we fix the share of baryons in the present energy density to Ω0/b = 0.0458 [50], in accordance with primordial nucleosynthesis requirements… A more complete analysis should consider the growth of inhomogeneities and make the comparison of the model redictions with other observational data, such as the data on the matter power spectrum, supernovae of the type Ia and cosmic microwave background. Although preliminary analyses in this direction have already been made, a detailed analysis of observational data is left for future work… The generalized model of unification of dark matter and dark energy introduced in this paper opens a novel perspective on Chaplygin gas and its modifications and generalizations… This relation connects the quantity governing the growth of inhomogeneities with the quantity determining the global evolution of the universe. This feature might allow easier and more direct transformation of the phenomenological knowledge acquired from the data into workable models of the dark sector.”

    Yes this paper explains it all. DE + DM = DARK CHOCOLATE.
    Of course the research is theoretical and must be vetted and supported by observations. The authors have not named this unification; but I strongly insist that it be called Dark Chocolate!!!

  121. #121 Wow
    August 3, 2012

    And best of all, Dark Chocolate HAS NOT been disproven by the Michelson-Morley experiment!

  122. #122 Chelle
    August 3, 2012

    “And best of all, Dark Chocolate HAS NOT been disproven by the Michelson-Morley experiment!”

    So true, it was the white ‘luminiferous’ chocolate that got busted.

  123. #123 Wow
    August 3, 2012

    Nope, it was the Aether that the Michelson-Morley experiment busted.

    No chocolate involved at all.

  124. #124 Chelle
    August 3, 2012

    Yeah sure, it was the Higgs Aether, that physics professor talked about as if it was honey, that the Michelson-Morley experiment busted.

  125. #125 Wow
    August 3, 2012

    Nope, you still have it wrong.

    Even you think it 99% certain you have it wrong.

  126. #126 Chelle
    August 3, 2012

    No, it is YOU incompetent idiotic swine, that got it wrong. Everybody in the world knows what Aether is about, it is only you that needs to keep on trolling. Grow up and try to learn something here, read the quote from the professor, if it was for idiots like you there still would be no confirmation of a Higgs Aether.

  127. #127 Wow
    August 3, 2012

    Nope, you igot it, as per usual, wrong. No Higgs aether.

  128. #128 chelle
    August 3, 2012

    > “i got it, as per usual, wrong.”

    It seems that the subconscious mind that cannot lie, also had it’s say. Take care.

  129. #129 Wow
    August 3, 2012

    Whst on earth are you eittering on about now?

    There is no such thing as the higgs aether.

    There,s the higgs field, which has a paricular meaning in physics. But you can’t go all Humpty-Dumpty and just make up your own private language.

    And getting all pissy and dumb about it won’t make it better.

  130. #130 chelle
    August 3, 2012

    “There is no such thing as the higgs aether…. you can’t go all Humpty-Dumpty and just make up your own private language..”

    Go and tell that to the professor:
    http://www.stargazette.com/article/20120713/VIEWPOINTS02/207130302

  131. #131 Wow
    August 4, 2012

    No need. The professor already knows it isn’t the higgs aether.

    Did you just, as usual, google “aether” and pick a link and not bother to read it?

  132. #132 chelle
    August 4, 2012

    Google is my friend :mrgreen:

  133. #133 OKThen
    Your own worst enemy
    August 6, 2012

    But you are your own worst enemy!

    All the information and data in the world are just a jumble of bits; without a focused our mind to see and understand the insights and ideas of the great men and women of science (or art, or politics or…; but this is a science blog).

    Such re-creation of the great ideas of science is the first step in the fun (the recreation) of science.
    The second step is to create our own learning hypothesis.
    The third step is to seriously test our learning hypothesis; because no amateur scientist can bear to hold a hypothesis that is easily broken.
    In the cycle of learning, the student of science continually learns from his misunderstanding.

    But the point of view of the pseudoscientist is not a learning cycle; it is a fixed point view that does not change.

  134. #134 Yandy
    October 17, 2012

    Can a black hole create dark energy? What if this is the smallest reduction that something can broken into.

  135. #135 Göran Rosander
    Sweden
    March 5, 2013

    Redshift of galactic light is said to depend only on the Doppler Effect. But it is admitted, (at least silently) that the photon could theoretically loose energy to some still unknown mechanism. But such a mechanism or process can never affect the light characteristic of super novae f.ex. from type 1A. If the light curve from a supernova type 1A is extended, from typically 20 days in our galactic neighborhood, to f.ex. 40 days, then no ‘tired light’ mechanism can be made responsible; the Doppler Effect is said to be the only reason. That is false, which I will show by the following gedanken experiment:
    We have placed out in space, some billions of light years away, a powerful laser directed against the Earth, under the following conditions:
    1. The laser does not move relatively to the Earth.
    2. We have a ‘tired light’ mechanism in space.
    3. The speed of light is constant = c.
    We receive the laser’s light in our laboratory here on Earth and find that the tired light mechanism has redshifted the light.
    The laser is governed by a very exact flip-flop that keeps the laser on for one sec. and then off for one sec. and so on. The flip-flop is so exact, that when the laser was tested here on the Earth the laser always sent the same number of light wave maximas during its on periods.
    We count the maximas and find that the universe has not taken away any number of the maximas; the numbers are the same as when we tested the laser here on the Earth. Of course we are not surprised to find that the flip-flop has increased its period length with exactly the same factor as the wave length has increased.
    The same way ‘tired light’ mechanisms affect the frequency of the laser they also affect the frequency of the flip-flop and ought logically to affect super novae light characteristics.
    My thought experiment does not prove that such a ‘tired light’ mechanism exists, but if it exists, it will also lengthen the light curve of supernovas.
    Consequently, regardless of if a ‘tired light’ mechanism exists or not, no measuring of supernovae light curves or other timed events in space will correct or add to the information we already have by measuring the redshift of light.

  136. #136 CB
    March 5, 2013

    “Of course we are not surprised to find that the flip-flop has increased its period length with exactly the same factor as the wave length has increased.”

    Why are we not surprised by this?

    A “tired light” mechanism that decreases the energy of light in a way proportional to distance, as is a necessary requirements to explain the supernova redshift data, also has a *local* effect on time that exactly matches the effect of all the Mpc of space between that local frame and earth? And also every other observer at different relative distances? That’s not possible.

    The flip-flop’s local operation should not be affected by anything dependent on distance or motion relative to an observer. In the absence of relative motion, therefore, the time from the first photon to the last in each pulse should be the same for all observers.

    In its reference frame, the time of each pulse is always the same. Relative motion versus other reference frames explains both the red-shift and time-lengthening of these pulses. Tired light does not.

  137. #137 Göran Rosander
    Sweden
    March 8, 2013

    CB – You have not understood the consequences of my experiment. I’ll try to explain it in another way. If you feel me being sarcastic, it is not my intention.
    The light pulse, governed by the flip flop have always the same number of light maximas, I hope you will agree to that. A one sec. pulse of light will be 300.000 km. long. The number of maximas x the wave length was 300.000 km when we measured it here on the Earth.
    But when we receive it from outer space, it is redshifted. That means that number of maximas x the wave length is more than 300.000 km. The speed of light = 300.000 km/s = constant. Consequently, the flip-flop has lengthened its period. Period.
    The thought experiment iI have demonstrated above is so simple, that everybody with some power of logical thinking, will understand the experiment. Understanding physics is hardly required. But the brain must function, and not being completely destroyed by big bang mumbo jumbo.
    Eric Lerner writes that bigbangers are recognized by the essential sloppiness of their thinking. Hard words, but after this answer to my gedanken experiment, I fully agree.

  138. #138 Wow
    March 8, 2013

    “The light pulse, governed by the flip flop have always the same number of light maximas, I hope you will agree to that.”

    That statement is bare assertion. No proof as to why it should always have the same number of “maximas”. I assume you mean the same wavenumber?

    “A one sec. pulse of light will be 300.000 km. long.”

    Incorrect and this has nothing to do with number of maximas.

    It even precludes quantisation of light into photons. A light that lasts 1 second produces a massive number of photons. Not one that lasts 1 second.

    Most photon production events last of the order of picoseconds. Metastable decays (such as the one used to determine the length of a metre) may last milliseconds.

    Your model of a photon is completely unscientific and is counter to all observed phenomena.

  139. #139 Göran Rosander
    Sweden
    March 8, 2013

    Wow –“The light pulse, governed by the flip flop have always the same number of light maximas, I hope you will agree to that.” That statement is bare assertion. No proof as to why it should always have the same number of “maximas”.”
    Do you know that a laser is a very stable oscillator? If you have a stable oscillator governed by stable flip-flop, then you have a firm number of maximas every time the flip-flop goes on. You say that this an assertion?
    “Your model of a photon is completely unscientific …”
    Have I mentioned the word “photon”?
    Where is my “unscientific model of a photon” in my text?
    As we are speaking of the space and a laser beam, I must comment on your statement “A one sec. pulse of light will be 300.000 km. long.” Incorrect…”.
    Sooo, and what length do you consider it to have?

    Well, I consider your answer even worse than CB’s. I thought the quality of the scientific discussion would be high here in the U.S. Now I find myself confronted by a belief system, where not even a thought experiment is understood as a thought experiment but as some sort of scientific investigation. Lucky you two that you were not students of A.Einstein…. Or rather, lucky Einstein…

  140. #140 Wow
    March 8, 2013

    “Do you know that a laser is a very stable oscillator?”

    No, not even laser physicists know that, because it’s absolutely wrong in every way imaginable.

    “Where is my “unscientific model of a photon” in my text?”

    In this bit:

    A one sec. pulse of light will be 300.000 km. long. The number of maximas x the wave length was 300.000 km when we measured it here on the Earth.

  141. #141 Wow
    March 8, 2013

    “Sooo, and what length do you consider it to have?”

    One second.

  142. #142 Wow
    March 8, 2013

    Oh, and since you appear now to insist that photons don’t exist, I really don’t think you get to mention Albert Einstein.

    Maxwell, maybe. Not Einstein.

  143. #143 Wow
    March 8, 2013

    “If you have a stable oscillator governed by stable flip-flop, then you have a firm number of maximas every time the flip-flop goes on.”

    No light source wears sandals.

    No light source at the photon level is “governed by a stable flip-flop”.

    And no indication that any light can be considered a stable flip-flop.

  144. #144 CB
    March 8, 2013

    “But when we receive it from outer space, it is redshifted. That means that number of maximas x the wave length is more than 300.000 km. The speed of light = 300.000 km/s = constant. Consequently, the flip-flop has lengthened its period. Period.”

    I will accept the premise that your light source emits a constant number of photons during each pulse.

    I will accept the premise that “tired light” and not relative motion causes the photons in these pulses to lose energy and thus be red-shifted by the time they reach earth.

    These are the two premises of your thought experiment, which I take as givens or postulates.

    It is NOT a consequence of these two premises that the length of the pulse would be widened once it arrives at earth. The time from the emission of the first photon to the last photon at the flip-flop would be the same as the time of arrival of the first photon to the last photon at earth.

    The speed of light is constant. By the second postulate, the flight path and distance covered by each photon is the same. Therefore the time of flight of each photon is the same. Therefore the time from first to last photon, the time-length of the pulse, is the same at reception as it is at transmission.

    I understood your thought experiment just fine. I also understood the actual logical implication, which you did not. The simple logic above demonstrates this conclusion is untrue.

    As a consequence, tired light cannot explain lengthening of supernova light curves, while relative motion — which DOES change the distance traveled by subsequent photons in the ‘pulse’ — explains it perfectly.

    “Pulse length is necessarily the same as # photons * wavelength” is wrong. You don’t even need your thought experiment to show this — any common scenario involving photons demonstrates this, which is what Wow was getting at.

  145. #145 Göran Rosander
    Sweden
    March 8, 2013

    I have thought about some stuff, and I don’t want to participate in a discussion where my opponents think that a scientific discussion consists of repeating words like “Metastable decays “… quantization (I hope you meant that)..” “..reference frame,..” etc without a logical scientific thought. I will answer those I think can benefit from my answers. Had one of you two, CB or Wow, said for instance ‘that according to my view of spacetime the only thing you have proved is the impossibility of light loosing energy,’ well an interesting thought. But that, like accepting a thought experiment, implies that a capability to think exists.

  146. #146 CB
    March 8, 2013

    So, you don’t think a scientific discussion about light consists of discussion of how light actually works?

    I accept your thought experiment. I do not accept your conclusions, because of the unphysical assumption that the length of a pulse of light changes if the wavelength of the component photons changes. This is demonstrably untrue. Ergo your conclusion is not true either.

  147. #147 Wow
    March 8, 2013

    a scientific discussion consists of repeating words like “Metastable decays “

    Uhm, if you don’t like scientific words, then you’re going to have problems having a scientific theory.

    I will answer those I think can benefit from my answers.

    Sorry, science isn’t about that. Your answers have to benefit science, not some gullible fool you want to impress.

  148. #148 Wow
    March 8, 2013

    for instance ‘that according to my view of spacetime the only thing you have proved is the impossibility of light loosing energy,’ well an interesting thought

    Except that isn’t an interesting thought.

    It’s not even a result of thinking.

  149. #149 Wow
    March 8, 2013

    “Pulse length is necessarily the same as # photons * wavelength” is wrong.

    Hell, this would require that a photon be emitted in the time for one wave to complete, and for each to run one after the other with neither break nor overlap.

    Both completely unphysical.

  150. #150 Wow
    March 8, 2013

    I’ll also note for the gallery that you’ve changed your tired light theory already.

    Originally:

    The number of maximas x the wave length was 300.000 km when we measured it here on the Earth.

    Changed to:;
    Pulse length is necessarily the same as # photons * wavelength” is wrong

    I.e. you used to say “#of maximas”, now you say “#of photons”.

  151. #151 CB
    March 8, 2013

    That was actually me, Wow, changing from the meaningless “maximas” to meaningful “photons”.

    Which is what is weird about this — the argument only begins to make sense if you assume Einstein didn’t deserve his Nobel for the photoelectric effect (so much for that chump, amirite?) and use a completely Maxwellian wave theory of light.

    However, in a wave theory of light the energy in light is only proportional to intensity, not frequency. If “tired light” decreases the energy of light in a wave theory of light, then the only effect would be a reduction in intensity. The *only* way to get redshift in a wave theory of light is via Doppler Effect.

    Which is why every “tired light” theory I’ve ever heard before this has been based on the modern, photonic theory of light (aside from the obvious ‘incorporating modern century-old physics’ angle). Because it’s only in the photonic theory that there is a relationship between frequency and energy of photons, and therefore the only mechanism by which reducing energy can result in a reduction in frequency.

    The photonic tired light theory runs afoul of the observations of supernova light curve lengths.

    The wave tired light theory runs afoul of over a century of observation on the nature of light.

  152. #152 CB
    March 8, 2013

    “The wave tired light theory runs afoul of over a century of observation on the nature of light.”

    And also runs afoul of the pre-quantum theory of light on which it is based.

    I forgot to mention that part.

  153. #153 Wow
    March 8, 2013

    I know you were quoting, CB. I was underscoring that it’s “not even wrong”, like the “lasers are stable oscillator”, it’s wrong in just about every way possible.

    Maybe a few more.

  154. #154 Wow
    March 8, 2013

    Oh, I see what you mean. OK, so Goran is still considering that light is one long photon for as long as it shines?

    The photoelectric effect says otherwise. Like A. Einstein said.

  155. #155 CB
    March 8, 2013

    I’m just saying that they didn’t change their story. Maxima to photons was my change. They never mentioned photons except to ask “where did I mention photons?” I had falsely assumed that they meant to talk about photons, or at least try to be compatible with early 20th century experiments on the nature of light and so could safely make that change.

    Instead, they are “not even wrong” as you say. Or “really, really wrong regardless of what light theory you use” as I would put it. :)

  156. #156 CB
    March 8, 2013

    Yeah, that. I guess Einstein is simultaneously the perfect example of someone who understands thought experiments, and a big dummy who doesn’t understand light (and screw all those *actual* experiments that agree with him).

  157. #157 Sinisa Lazarek
    March 8, 2013

    there is an issue with tired light that both CB and Wow didn’t mention, so I will.

    If tired light actually existed, and “c” was constant, then you would get dispersion effect when viewing the source. We don’t see that when observing the skies.. not on objects 1 l.y. away.. not on object 3 billions of l.y. away.
    Secondly, the CMB pattern distribution would look very different, again.. not what is observed.

    So theoretical concepts aside… it just doesn’t seem to exist in real life.

  158. #158 Carl Johan Soderquist
    March 8, 2013

    Well, first of all there is a thin but skarp line between science and technology. The technical qualities of a laser with a stable oscillator, governed by a flip flop, is not a scientific assertion when used as a scientific tool in a well defined experiment in physics. Furhter more single photons belong to the realm of particle physics. And beams of photons have physical qualities different from those of single photons. As assered by Mr. Rosander himself, he is not discussing particle physics. He is using instruments and well-defined conditions that are irrefutably working the way he claims they do. However, as far as I can see, Mr. Rosander’s experimental redshift takes place within a frame of inertia. The totality of the Doppler redshift does not take place during the “journey” of a light beam. Instead, the totality of the Doppler redshift is caused at one single sutface, i.e. at the surface of the radiating light source. If Mr. Wow is a physicist, he is bound to know that. Furthermore, if the redshift of the lights of the stars we observe, had been caused by a Doppler effect, the this effect is totally incompatible with Einstein’s field equations of his geneeal theory of relativity and totally incompatible with the known solutions of those equations. Only if the rdshift would be caused by i difference of gravitational potential between the stars and the observer, then the redshift would take place gradually between the stars and the observer i proportion to the change of the gravitational potential thet the beam is subjected to. And the observed flip-flop frequency of the laser would diminish at the same rate as the gravitational redshift. But then the redshift will not take place within a frame om inertia. Further more, it’s quite easy to calculate that a mere fraction of the observed redshift is caused by gravitational redshift if we are not involving anomalies like dark matter and dark energy.
    Among numerous watertight evidence that the red shift cannot be caused by the Doppler effect, I can mention one proof essentialy made for children. It reads as follows: At a specific cosmologal instant, simultaneous for all the Universe, we make a three-dimensional map in which each object in the Universe is alloted its specific radial space coordinate. These coordinates refer to everything from the universe’s largest objects down to molecules and electrons. If we have a Doppler effect governing rhe redshift, then, as time goes by, the spatial coordinates for all items must increase in the radial direction from the center of the earth, provided that we choose that center as our arbitrary coordinate center. Then, all items are receding faster the farther from the center of the earth they are located. Also, the earth is constantly growing since its matter is of course involved in the expansion. And so do the molecules and atoms that Earth is made up of. All electron trajectories move away from their respective nuclei. And become free electrons. It is easy to prove that all matter will collapse at the slightest disturbance of the size of the electron paths. And we can observe how the universe in a relatively short distance from us.will blow up into radiation energy.

    This story is for children who use to laugh when told that many astronomers think we should long ago have terminated our existance. That we still exist is a indigestible anomaly.

  159. #159 Wow
    March 8, 2013

    Do you really think that a change of name and the same wall of bollocks is convincing anyone here?

  160. #160 Wow
    March 8, 2013

    “And beams of photons have physical qualities different from those of single photons.”

    No they don’t.

    Sheesh, same old codswallop.

  161. #161 Carl Johan Soderquist
    March 9, 2013

    It’s ridiculous that Wom should think that there should be a crack in my argumentation if I call an apple an apple while Rosander calls a pie a pie. Worn, if I may say so, your arguments are not scientific but bears all the characteristics of impatience at being stumped. And didn’t you realize, Worn, that Rosander’s reasoning was NOT based on the hypothesis of tired light. He writes that “regardless of if a ‘tired light’ mechanism exists or not….”.
    Sinisa is correct about the classical theory of tired light. There is an even simpler proof than the one Sinisa made ​​use of to refute the theory of tired light: Light of a short wavelength carries more energy than light of a long wavelength does. Thus under the influence of tired light effects, the amount of displacement of the spectral lines of shortwave light should be larger than the displacement of longwave light. Which no observation could corroborate.
    The difference between simple photons and a light or laser beam of photons has since long been established by both scientists and engineers. Usually when microscopic objects are hit by a beam of light, they are forced along the direction of the beam by the light photons. That radiation force was first identified by the German astronomer Johannes Kepler in 1619 when he observed that tails of comets always point away from the Sun. But A real-life “tractor beam”, which uses light to attract objects, has been developed by scientists.
    The research, published in Nature Photonics and led by the University of St Andrews, is limited to moving microscopic particles. It is not the first time science has aimed to replicate the feat – albeit at smaller scales. In 2011, researchers from China and Hong Kong showed how it might be done with laser beams of a specific shape – and the US space agency Nasa has even funded a study to examine how the technique might help with manipulating samples in space.
    And, by the way, Albert Einstein has proven that the velocity of light in the gravitational field is a function of the gravitational potential of a place in the field. Thus he could easily infer that light-rays propagated across a gravitational field undergo deflexion. Thus we got the gravitational lensing. When Edwin Powell Hubble made systematic observations from which he could conclude that light from distant objects in the Universe was more red-shifted that light from less distant objects, he concluded that “There is a mechanism by which it APPEARS to indicate that the universe expands”. He was bright enough to understand that jumping to conclusions is not a characteristic of a scientist, but rather a “a feature that is characteristic of a fantasy amateur” (the quote rendering a finding that Einstein made). The Friedmann–Lemaître–Robertson–Walker (FLRW) metric is an exact solution of Einstein’s field equations of general relativity. These solutions, forming the basis of the Standard Model, prove that Hubble was right to doubt that the observed red-shift was caused by the Doppler effect.

  162. #162 Wow
    March 9, 2013

    It’s ridiculous that Wom should think that there should be a crack in my argumentation if I call an apple an apple while Rosander calls a pie a pie.

    Except you’re not calling an apple an apple nor he a pie a pie.

    He’s calling a pie a unicorn and you’re calling an apple a heffalump.

    The difference between simple photons and a light or laser beam of photons has since long been established by both scientists and engineers.

    Yeah.

    No difference.

    Look, we ALL know you’re just doing this because you will not and cannot go to THIS thread

    http://scienceblogs.com/startswithabang/2012/09/23/weekend-diversion-you-are-responsible-for-what-you-say/

    to pour your load of bollocks on, hence your continual sockpuppeting to avoid it.

    Stop polluting thread with your woomancering.

  163. #163 Carl Johan Soderquist
    Current Location Lund
    March 9, 2013

    Wow, you must be ignorant of the following fundamental facts. The oldest enigma in fundamental particle physics is: Where do the observed masses of elementary particles come from? Inspired by observation of the empirical particle mass spectrum we propose that the masses of elementary particles arise solely due to the self-interaction of the fields associated with a particle. We thus assume that the mass is proportional to the strength of the interaction of the field with itself. A simple application of this idea to the fermions is seen to yield a mass for the neutrino in line with constraints from direct experimental upper limits and correct order of magnitude predictions of mass separations between neutrinos, charged leptons and quarks. The neutrino interacts only through the weak force, hence becomes light. Yes LIGHT or photons. And cluster of photons are observed to behave different from singular photons. Where? In the The Large Hadron Collider (LHC), which is the world’s largest and most powerful particle accelerator. Wow, I find a surprising lack of scientific method in your argumentation. You either respond with invectives or with unsupported claims. For that reason I must conclude that you are a High School pupil with a long way to go before you can earn the right to call yourself a physicist. I therefore find it unjustified to extend your ability to try responding on science based logical reasoning with your boring unsupported claims.

  164. #164 Wow
    March 9, 2013
  165. #165 Wow
    March 9, 2013

    I find no science in your walloftext, and must assume you’re a homeschooled idiot.

  166. #166 Sinisa Lazarek
    March 9, 2013

    “The oldest enigma in fundamental particle physics is: Where do the observed masses of elementary particles come from?”

    well, not since last year. Actually theoreticaly not an enigma since 60’s.

  167. #167 CB
    March 9, 2013

    “Among numerous watertight evidence that the red shift cannot be caused by the Doppler effect, I can mention one proof essentialy made for children.”

    Because only children, who breathlessely accept their parents telling them that the Easter Bunny sneaks into their house to hide colored eggs, would buy it?

    The rate of regression is proportional to the distance from the chosen center. It’s only significant on scales of MPc. It’s not measurably significant even on the scale of our galaxy, or Local group. On earth? Forget it. If our only source of information was our own planet, we would never observe the effect because it is completely ignorably tiny here. The continued existence of earth demonstrates nothing, unless you know nothing. So those swayed by this argument would be children, and you. And I wouldn’t bet much on the children.

  168. #168 Carl Johan Soderquist
    Still in Lund
    March 10, 2013

    No CB, because your reasoning is on the level of children’s reasoning. The only two of you having proven to be serious, sober and knowledgeable during the time I was a guest here, are Sinisa Lazarek and Goran Rosander. But Sinisa, as regards the masses of the currently known elementary particles, I am fully aware that their masses have been determined empirically within some more or less known margins of error. What I’m talking about is the mass property of these particles. It can not be determined or predicted theoretically because the standard model of particle physics contains at least 18 free parameters involving mass. The size of each of these parameters can not be predicted theoretically. And if neutrinos are proven to be strictly massless, then the problem becomes even worse. Because then the number of free parameters increase considerably. The reasons of the problems now highlighted are difficult to explain, because it would take a lot of theoretical effort to illustrate their background. In short, the problem boils down to the techniques of renormalizing. In quantum field theory, the statistical mechanics of fields, and the theory of self-similar geometric structures, renormalization is any of a collection of techniques used to treat infinities arising in calculated quantities. When describing space and time as a continuum, certain statistical and quantum mechanical constructions are ill defined. To define them, the continuum limit has to be taken carefully. Renormalization establishes a relationship between parameters in the theory, when the parameters describing large distance scales differ from the parameters describing small distances. Renormalization was first developed in quantum electrodynamics (QED) to make sense of infinite integrals in perturbation theory. Initially viewed as a suspicious provisional procedure by some of its originators, renormalization eventually was embraced as an important and self-consistent tool in several fields of physics and mathematics. However, renormalization illustrates why it is not possible to give the particles in the standard model mass as an intrinsic property, even if the existence of the Higgs particle is proven. So it is a tale that the Higgs particle would solve the problem of how and why elementary particles acquire that specific property that we empirically call “mass”. Within the framework of the macrocosm, the “mass” was a concept coined by scientists before Isaac Newron did so. But Newton coined it as e necessary element of his theory of gravitation and inertia. But Newton’s gravitational constant is yet another example of how impossible it so far has been to theoretically explain the magnitude of this constant. Which is why this constant can not be determined precisely, but only empirically. Although Einstein was an example of a highly sophisticated theoretical physicist whose theoretical theories hitherto have been verified through empirical experiments, he did not much to help solve the mystery of mass, gravitation and inertia.

  169. #169 Carl Johan Soderquist
    Lund
    March 10, 2013

    Sorry Sinisa, I made a wrong statement about the free parameters of the standard model of particle physics. The correct statement is that if neutrinos are proven NOT to be strictly massless, then the problem becomes even worse. Because then the number of free parameters increase considerably.

  170. #170 Wow
    March 10, 2013

    More complete rubbish which should be taken to

    http://scienceblogs.com/startswithabang/2012/09/23/weekend-diversion-you-are-responsible-for-what-you-say/

    because you’re off topic and talking complete bullshit.

  171. #171 Sinisa Lazarek
    March 10, 2013

    @ Carl
    “What I’m talking about is the mass property of these particles.”
    – yes.. like I said before… the mass property comes from Higgs mechanism and the manner of coupling.

    ” It can not be determined or predicted theoretically because the standard model of particle physics contains at least 18 free parameters involving mass.”
    – I wouldn’t say that’s the reason. You can’t predict it because QM as a theory and as a model doesn’t allow it. The masses are described in Plank units.. QFT doesn’t have a fundamental lenght, so its only natural that you can’t predict any fundamental value as such. I guess the best any such theory could get is ratios, but not actual real numbers.

    I guess that if you had a more “fundamental” theory that becomes QFT (like string theory or others) you might be able to get some mass value as a coupling constant for a given particle.

    But all in all, I don’t understand what you are talking about. It’s not an enigma, because the process is know. No, you can’t predict the mass of a hypothetical particle because the theory and mathematics don’t work that way….

    What does all of this have to do with Dark Energy?

  172. #172 Wow
    March 10, 2013

    “What does all of this have to do with Dark Energy?”

    Nothing, which is why they ought to be going here:

    http://scienceblogs.com/startswithabang/2012/09/23/weekend-diversion-you-are-responsible-for-what-you-say/

    Except they aren’t here to inform or be informed but to clog up every thread with their idiocy, which isn’t going to happen if they posted to the relevant thread, so they don’t do that.

  173. #173 Carl Johan Soderquist
    Lund
    March 10, 2013

    1. Dark Energy was invented as a necessary patch to explain observations since the 1990s which purportedly “must” be interpreted to indicate that the Universe is expanding at an accelerating rate. At least if it’s considered a necessity to uphold the hypothetical “validity” of the Standard Model of Cosmology.
    2. This construction of “validity” stems from a very hypothetical interpretation of the Red shift according to which it constitutes a necessary but not sufficient fundament of the Standard Model of Cosmology. One could succinctly say that this hypothetical interpretation of the observed Red Shift keeps the Standard Model from derailing.
    3. Why keep the Standard Model from derailing when there are a number of alternative explanations of the Red Shift? If you say that there exist no alternatives and will never exist any alternatives without even testing them, then you are lost in your own self-sufficiency. The answers to the question why the Standard Model must be kept running hasn’t anything to do with science.
    4. The answer is that there has been invested a huge amount of money and cultural propaganda (and even religious propaganda) into keeping the Standard Model of Cosmology running. Another answer is that the community of science is conservative for reasons that may be well understood. A student would be unhappy with investing a lot of studies and time and money into something being scrapped the next day. And professors wouldn’t like to have to face a totally new understanding of their science. But the history of science shows that such paradigm shifts are characteristic of all serious science.
    5. It is quite good that classical alternatives like “tired light” are done with as outdated.
    6. Science will however not remain science if not allowing the scientists to keep their minds open to the possibility that a minority of them – sooner or later – not might, but must employ new mathematical models and abstractions in order to rationalize, explain and above all predict natural phenomena on the basis of the principle of parsimony, economy, or succinctness used in logic and problem-solving. Study some theory of science and you will understand these issues better.
    7. The models of quantum mechanics and particle physics may be affected by the inevitable imperfections of all science, but these models may still constitute some of the tools required to meet the necessity to renew today’s cosmology. In a forum of scientific discussions you cannot require a commentator to present the compilation, determination and proof of new theories. Instead you should make allowance for suggestions and even questions. To dig yourself in behind the barricades is oldfashioned Euroepan style and will be quite counterproductive. From Wow I expect no other answers but the usual bilge English. I might at least expect some Shakespeare quotes. Of course I accept Sinisa’s explanation as an alternative to the explanations made by scientists in their latest progress in the fields of QM and QFT. Remember however that though it might seem there supposedly is built a fundamental length into the Friedmann solutions of the EFEs and thus also built into the Standard Model of Cosmology, there exists no such fundamental length in that model. Panta rhei. If you don’t believe me, you better start studying your advanced math.
    8. Finally, don’t forget that sooner or later today’s Standard Model of Cosmology will become the ridiculous cosmology of yesterday. If you cannot discern the link between productive criticism of DE and the tools that might topple today’s Standard Model of Cosmology, I must conclude that I cannot reach you. Whatever, I now stay my case.

  174. #174 Sinisa Lazarek
    March 10, 2013

    @Carl

    1 – yes.. DE is just a name placeholder for now.

    2 – Mostly no. I guess it’s 50-50. The reason comes from FLW Metric. Or before that, from GR. GR universe just isn’t a steady state universe. At it’s best it’s meta stable at some time interval. So, it’s mostly likely contracting or expanding, the metric, that is. So you go out and look. And what you see is that it’s not in a steady state and it’s not contracting. In fact, it behaves like it’s expanding. And call it what you will, DE, vacuum energy density, post inflation field.. whatever.. Something is out there. Tired light doesn’t work. Maybe something else will. I don’t know why it seems no one is allowing new theories. Far from it. But a theory that can be falsified in 30 seconds isn’t good enough. Or worse, a theory that already has predictions other than those observed.

    And I wouldn’t say that “Finally, don’t forget that sooner or later today’s Standard Model of Cosmology will become the ridiculous cosmology of yesterday.”

    For one, this really shows you have some deep anger with modern cosmology, but haven’t offered any working alternative. And secondly, I don’t find ancient astronomy ridiculous. Far from it, I find ancient greek and egyptian and mayan astronomy fascinating. What they knew and calculated with nothing more than a rope, stick and brain is amazing to me.

    “If you cannot discern the link between productive criticism of DE and the tools that might topple today’s Standard Model of Cosmology”
    Am sorry, but what are tools that topple today’s Cosmology? And we talking about the observation of Universe accelerated expansion. Tired light doesn’t explain it. What does? Forget DE for a moment. What does explain it?

  175. #175 Len
    April 18, 2013

    Read this.
    http://arxiv.org/abs/1107.4045
    Publicated in Phys. Rev. D.
    Quite interesting.

  176. #176 Bill
    Florida
    July 24, 2013

    Beyond the bubble-verse sea lies a loathsome, insatiable, infinite vacuum.

    The sea of bubble-verses seek forever to fill that vacuum, but the vacuum is truly infinite and endless. It can’t be filled . . . EVER!

    Nature’s endless outward push (from our perspective) to try to fill the infinite vacuum is labeled dark energy, (aka; aether), honey, cauliflower, anti-gravity and/or whatever else works
    to describe it.

    It is a force, but is it a useable force? That’s the real question. Then we should ask: How?

  177. #177 Paul Kronfield
    Houston TX
    October 3, 2013

    So dark energy exists everywhere in the universe, and is powerful enough to cause entire galaxies to accelerate. One would think we could harness this energy as the energy source of the future. Imaging transportation units driven by dark energy that could accelerate almost any mass to almost any speeds, or lift giant granite blocks. It would cause internal combustion engines to be obsolete and oil to become a worthless commodity. Is anybody working on this???

  178. #178 Sinisa Lazarek
    October 4, 2013

    @Paul

    “So dark energy exists everywhere in the universe, and is powerful enough to cause entire galaxies to accelerate”

    Well no, not really. It causes the space between galaxies to expand. Not “pushing” galaxies themselves.

  179. #179 Wow
    October 4, 2013

    “labeled dark energy, (aka; aether)”

    Nope, it’s not “also known as”.

    It’s known as dark energy. Aether is something completely different.

  180. #180 Michael Kelsey
    SLAC National Accelerator Laboratory
    October 4, 2013

    @Paul #177: Sinisa (#178) already explained this: the cosmological expansion doesn’t “accelerate galaxies”; the galaxies (or more properly, superclusters of galaxies, the largest graviationally bound structures), embedded in spacetime, just get carried along for the ride as that spacetime expands.

    Why can’t DE (or Lambda, or whatever it is) be used for technology? Because it is incredibly weak! You probably know that gravity is the weakest of the known forces (10^-41 vs. EM). Well, DE, treated as a “force”, is piddlingly weak compared to gravity. It only operates over huge cosmological distances; let me work through an order-of-magnitude calculation of the cosmic acceleration on a more local scale.

    The Hubble constant, H0, is roughly 70 km/s per megaparsec. On the scale of the solar system, let’s say 0.7 light day = 6e-4 parsecs, the recession velocity would be about 42 um/s (yes, microns!).

    The acceleration due to “dark energy” (Lambda, quintessence, whatever your favorite theorist wants to call it this week), is such that the scale factor of the universe a(t) will double in 11.4 billion years. That’s roughly saying that H(11.4 Gy) = 2*H0.

    We can convert that to an acceleration: On the scale of the solar system, delta(H) = 42 um/s/(11.4 Gy) = 1.2 x 10^-18 um/s^2 = 1.2 x 10^-24 m/s^2. That’s an effective acceleration for a gravitationally unbound test mass at the edge of our solar system, relative to the Sun.

    For comparison, Voyager 1 experiences a deceleration, due to the Sun’s gravity, of about 5.5 x 10^-7 m/s^2 at it’s current distance of 100 AU (the same distance I chose for my calculation :-). That is 17 orders of magnitude larger than the DE acceleration.

    That’s why you can’t use DE for technology.

  181. #181 Chatty
    November 10, 2013

    As simply as i could ask this…. – can dark energy be gravitational waves?

    According to what I have researched, I’m on 50-50 for yes and no. Do you think you could give me some explanation on this Ethan?

  182. #182 Wow
    November 11, 2013

    No is the simplest answer.

    They’re not strong enough, they would cause oscillations in where “dark matter” is both through time and space.

  183. #183 Jon Theurich
    UCI
    March 6, 2014

    A 2011 paper in the journal Physical Review D by Christos Tsagas, a cosmologist at Aristotle University of Thessaloniki in Greece, argued that it is likely that the accelerated expansion of the universe is an illusion caused by the relative motion of us to the rest of the universe. The paper cites data showing that the 2.5 billion ly wide region of space we are inside of is moving very quickly relative to everything around it. If the theory is confirmed, then dark energy would not exist (but the “dark flow” still might).[37][38]

  184. #184 Don
    Colton
    March 14, 2014

    I would like to open a discussion that dark energy is in fact anti energy caused by when the universe first formed as matter and anti matter reacted according to formula E=MC(squared). if M was anti matter what would the reaction produce? [anti energy]. due to the quantity of both during the big bang there would me a lot, just like there is a lot of dark energy also in the universe.

  185. #185 Michael Kelsey
    SLAC National Accelerator Laboratory
    March 14, 2014

    @Don #184: If you want to open a discussion about science, it usually helps to already have the basic facts in hand. The term “M” is an unsigned scalar, and is positive for both matter and antimatter. The mass of a positron (anti-electron) is the same 0.511 MeV as the mass of an electron.

    If it were not, neither the linear accelerator I use for my research, nor the detectors and data analysis I use, would function correctly.

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