Someone Hates Inflation!

Warning: Crazy talk ahead. Some of you may remember that I wrote about inflation and why its alternatives fail awhile back. Apparently, Louise Riofrio didn’t get the memo. When there’s misinformation about cosmology out there, it’s up to me to set the record straight. (And I am not alone.) Let me first remind you about one of the alternatives to inflation I debunked last month:

Add defects and vary the Speed of Light. This one’s out. Why? Because we would see defects in the Cosmic Microwave Background, and we don’t. The constancy of the speed of light is highly supported by experiments, but there is a theoretical disaster if it turns out that either c (the speed of light), G (the Gravitational constant), or h (Planck’s constant) changes: energy is no longer conserved in the Universe! It’s possible, but… yeesh!

Now, it is very important to consider alternatives to our cosmological model, and to test them as best as possible, both experimentally and observationally, as well as theoretically for consistency.

So let’s remember what inflation does for us: gives us a flat Universe, with the same temperature everywhere, without defects or ultra-high-mass relic particles, and the observed spectrum of fluctuations. Well, Louise comes out with this graph, which I assume comes from a popular science magazine:

Now, I’m not an expert on inflation, but I’m pretty adept with it. Inflation does not give a unique prediction like that for the angular correlation function. Each individual model of inflation does, but we don’t know what that model is. How do we figure it out? Measure the scalar and tensor indices, as well as other cosmological parameters, and then reconstruct the model of inflation from that. What’s Louise’s solution? Vary the speed of light and change the age of the Sun, Earth, and Universe. That could be why her work isn’t published in peer-reviewed scientific journals.

There is crazy out there, folks. Even from people with Ph.D. degrees, sadly. Does inflation solve everything? No. But is the speed of light constant? Well, we can place limits on its variation from two major sources:

1. Quasar Absorption Lines: These can be used to measure the time variation in the speed of light, as the frequency of the absorbers are highly dependent on whether the speed of light stays the same or not. (For those of you who are experts, this is the same experiment that measures variations in the fine-structure constant.) The results for this place limits on the variation of the speed of light, c, to change by less than 0.24% over the last 10-12 billion years. (Remember, if you will, that the Universe is only 13.7 billion years old.)

2. Natural Nuclear Reactors: the Oklo Nuclear Reactors have been going strong for nearly 2 billion years. By measuring the rate of radioactive decay and isotope abundances, we can determine how much the fine structure constant, and therefore how much the speed of light, has changed. The limits from this are that over the last 1.7 billion years, the speed of light has changed, at most, by 0.02%.

Now what is Louise’s prediction? That the speed of light, c, changes as the age of the universe to the minus-one-third power (i.e., c ~ t-1/3). Over the same time as Oklo (where t changes from 12.0 billion years to 13.7 billion years), that would correspond to a change in the speed of light of 4.5%, or over 200 times what is observed.

Verdict? Inflation, valid. This alternative? Invalid. Very, very invalid. And don’t let anyone, even the Carnival of Space (which I love, is great this week, and you should check out), tell you different. You’ve got the info, now, and you know better.

Comments

  1. #1 Greg
    April 24, 2008

    Where does the energy go for a photon that is redshifted from the expansion of space-time? In special relativity, for every redshift there is another reference frame where the photon is blueshifted and energy is conserved. But in the GR case of expansion, it seems like energy is not conserved. What’s going on here?

  2. #2 Tyrone Slothrop
    April 24, 2008

    Good post. I don’t think many people take Louise seriously (especially anyone with even a cursory knowledge of GR who takes a few minutes to read her papers). While plugging this for something like 3 years, she has never presented anything resembling a derivation for her equation. I suspect it is somehow concocted by equating unrelated terms like the R(t) that appears in the FRW solution and E=mc^2, or some such numerology.

  3. #3 ethan
    April 24, 2008

    Greg, the expansion of the Universe causes the photons to get redshifted. If the Universe were to contract again, you’d see it get blueshifted. The Universe isn’t constant, not in time, anyway. And so, as far as we know, photons losing energy with redshift is a consequence of the Universe’s expansion.

    Tyrone, thanks! Her work reminds me of a kid in high school who said “E=mc2,” and then said “E=1/2 mv2,” and solved the equations, and found “v=1.414 c”. Her mistake is a little less naive, but physically is still preposterous.

  4. #4 Kea
    April 25, 2008

    Before critiquing Louise’s theory, you should probably try to understand it better. First of all, constraints from quasar experiments only set hc to be constant, which Louise has specified. Secondly, although one may well manufacture empirically correct behaviours with inflation, that hardly recommends it as an elegant solution. Inflation doesn’t have to be correct because (a) your hero told you so or (b) you don’t like the colours Louise used on her graph.

  5. #5 ethan
    April 25, 2008

    Kea,

    I have. In fact, I have at length. First off, her derivation is bogus. Second off, it conflicts with experiments. Not just the QSO and Oklo experiments, but also Big-Bang Nucleosynthesis (which constrains h, by the way, check out Wasserman and Brecher 1978), and constraints on time-varying G (check out a number of papers by G. Raffelt).

    Louise may be charismatic and may have an interesting idea, but it doesn’t hold up when faced with the facts. It’s what we call an invalid theory. You can believe whatever you want, of course, but there’s a reason that this enterprise called “science” works the way it does.

  6. #6 Brian
    April 25, 2008

    This post reminds me of a certain former professor of ours.

  7. #7 Kea
    April 25, 2008

    Dear Ethan, you need to do a bit more homework than that. First of all, clearly any theory that plays around with hbar is a proposal for a quantum gravitational cosmology, not a classical one, and I have a feeling you might be way out of your depth on that one. I’m just a crazy quantum gravity theorist myself, but expecting Louise to revolutionize cosmology AND come up with a complete derivation from a theory of quantum gravity is probably asking a bit much. If those are the criteria you use to judge ideas, then you’re never going to spot the good ones, are you?

  8. #8 Kea
    April 25, 2008

    P.S. A fixed alpha is CONSISTENT with a varying c. You should listen more carefully.

  9. #9 ethan
    April 25, 2008

    Kea,

    First off, thanks for your comments. We certainly don’t have all of the questions answered, and it is definitely important to consider alternatives to the theories we do presently have.

    That said, any extensions to physics that we make must agree with the physics we have experimentally tested and observed in the classical limit. This includes classical quantum mechanics and nuclear physics. So the constraints we have on time-varying alpha combined with the constraints we have on the time-evolution of h and on G have to be satisfied by any new theory. And if you’re proposing a new theory (or Louise is, or anyone is), the onus is on you as the initiator of the new theory to show how your work satisfies the old constraints. And the old constraints are tight; we have experimental constraints on alpha, we have very good measures of the 21-cm line that constrain h, we have very good measures of BBN which constrain different powers of h and c, we have good constraints on time-varying G, and you have to show that the constraints we have are, indeed, satisfied.

    I don’t care about a complete derivation, although that would be nice. But I do care about having predictions that are in agreement with the physical world and also are testable in practice. I’m out of my depth in terms of doing quantum gravitational calculations for sure, but I’m pretty damned confident in my abilities to do the classical ones.

    And finally, you are way out of line in the combative tone you continue to take in your comments. I’m happy to continue this discussion if you can drop the ad hominem attacks (see the last sentence of every one of your comments if you need to know specifically what I’m talking about), but you have to drop them, or this is the last comment you’ll get from me.

  10. #10 L. Riofrio
    April 25, 2008

    Bravo Kea! It is about time someone answered Greg’s question about photon energy. We all know that photons have energy E = hc/(\lambda). There’s that constant hc again. Since mass is equivalent to energy by m = E/c^2, particles also have a gravitational potential U related to the Universe. Particle energy is then:

    E + U = hc/(\lambda) – (GM/R)(E/c^2)

    E + U = hc/(\lambda) – (GM/Rc^2)hc/(\lambda)

    Since R = ct and GM = (ct)c^2, we have:

    E + U = hc/(\lambda) – hc/(\lambda) = 0!

    The photon’s total energy is just 0, which applies to any particle right up to the biggest galaxy. Total energy of the Universe is zippo. It’s the ultimate free lunch, which explains how it expanded from a tiny point to the immensity we observe today.

    We still like him, but so far Ethan is not doing very well.

  11. #11 Kea
    April 25, 2008

    Yes, his blog photo is kind of cute.

  12. #12 Carl Brannen
    April 25, 2008

    Re Louise’s solution to GR field equations, maybe a couple of her blog posts will help: Einstein’s Field Equation, and Friedman is in the Air Today will help. I recall having seen much more detailed stuff, but it didn’t show up in a search for “field equations”. Maybe Louise will contribute.

    The basic problem is that as soon as a calculation is complicated enough to make any real calculation, it becomes difficult enough to understand that a person’s preconceived notions about the utility of the calculation will govern whether or not they will undergo the effort required to verify it.

    As an amateur, I had the same problem. My solution was to derive an equation so simple that it could be explained in one paragraph needing only high school algebra. I sent it to a few professional physicists, gave a few APS talks, and now I’m referenced in several peer reviewed journal articles with regard to that formula.

    If the reader predetermines that the theory is worthless, they will quit reading it after they find the first error, no matter how unimportant. Even a typo is likely to be enough as it indicates “lack of professionalism” — this despite the fact that most arXiv articles, even the generally correct ones, are loaded with typos, wrong terminology, and equation errors.

  13. #13 ethan
    April 26, 2008

    Here are the things that give me pause about the theory, and again, that must be explained by the theorist to verify its validity, and I am assuming, based on what I have read and what has been articulated to me, that h and c are fundamental constants that change with time, h as t^(1/3) and c as t^(-1/3), and the others, G, kB, e, the Coulomb constant, and particle masses stay constant:

    1. Is this consistent with everything we know about quantum mechanics? This includes high precision tests, like the constancy over time of the wavelength/width of the 21-cm line.
    2. Is this consistent with big-bang nucleosynthesis? If you’re changing h and c, you change the formula for reaction rates significantly. Do you predict anything that might be different from standard BBN that could be testable?
    3. On a theoretical note, why do you relate a particle’s rest energy to the gravitational potential of the Universe?
    4. What test can be done to verify that either c or h is changing as you advocate?
    5. How do you reconcile this with the temperature of the cosmic microwave background being what it is? Based on your equations, the Rydberg, or the energy for ionizing a hydrogen atom from its ground state, is time variable, scaling as t^(-2/3). So if photon energies are no different than they are in standard cosmology but the energy to ionize hydrogen scales as t^(-2/3), the Universe should not have recombined when it did. Energies for the hydrogen atom should have been different by a factor of 1000 at a time t=380,000 years. The hydrogen atom is well-studied and well understood; so is the physics of the CMB. How does this add up in your theory?

    There are a lot of simple questions like this that I can ask, and these are the types of questions that will need to be answered before you have a scientifically viable theory. Of course, if you can answer them, I’d love to hear it!

  14. #14 Kea
    April 26, 2008

    Well, I’ll leave Louise to answer these particular questions, as she has done previously, but note that 3. is particularly interesting. Those of us who see something in this cosmology, eg. Pitkanen, have different interpretations of 3. It goes back to Mach’s ideas of inertia, which strongly motivated Einstein, but could not be incorporated properly into GR due to the strictly local nature of Riemannian geometry. In a modern context, I like to begin by picturing a beam of mixed charged leptons in a mass spectrometer, where inertia splits the beam into 3. This treats rest mass as a quantum number and Mach’s principle is elevated to a holographic one, which is very similar to what some string theorists have in mind.

  15. #15 L. Riofrio
    May 2, 2008

    Now it’s Ethan’s turn:
    1. How do you reconcile inflation with the First Law of Thermodynamics?
    2. Relativity is quite specific that information can not travel faster than light. If just before onset of inflation you placed two matching signals a short distance apart, would inflation would carry their information faster than light?
    3. Why would inflation stop at just the right time to leave the Universe at a critical density? Why not just inflate forever?
    4. Why has nothing like an “inflaton” ever been observed in nature?
    5. How could inflation ever be demonstrated without approaching the energies of the Big Bang?

    Your questions are interesting too, particularly as they relate to wavelengths of radiation.

  16. #16 ethan
    May 3, 2008

    Louise,
    I’ll do yours if you do mine. And, as a show of good faith, I’ll do yours first.

    1. You don’t. Energy conservation as you assume it assumes that we know how to calculate the work done to expand the Universe, which we don’t know how to do. I can define work in such a way as to make energy conserved, but it’s ad hoc.
    2. This is a common misconception about relativity. It says nothing about information, but only about two particles and their local motion relative to one another. See the twin photon experiment for an example of information traveling faster than light terrestrially.
    3. It doesn’t need to. Inflation, to give a critical density, requires about 64 e-foldings of inflation, regardless of initial conditions. You can have arbitrarily more and you’ll still get a flat, critical Universe.
    4. The same reason that GUT-scale particles have never been observed in Nature: they are unstable and require higher energies than we have the capabilities of creating in order to make them.
    5. I just explained to you, when I wrote about how to destroy the Universe, that that is the only way to make inflation happen. We have to look for indirect evidence, i.e., relics of inflation, to support it. That’s like saying how do we demonstrate the big bang? Well, you don’t, but you look for its unique predictions and test them. Same thing with inflation. (And Lawrence Krauss was wrong for saying his theory is indistinguishable from inflation.)
    Hope this answers your questions to your satisfaction. So, now I hope you can address my questions!

  17. #17 L. Riofrio
    May 5, 2008

    1. Is this consistent with everything we know about quantum mechanics? This includes high precision tests, like the constancy over time of the wavelength/width of the 21-cm line.

    As far as can be determined, the 21-cm hydrogen line is affected by redshift but not by c.

    2. Is this consistent with big-bang nucleosynthesis? If you’re changing h and c, you change the formula for reaction rates significantly. Do you predict anything that might be different from standard BBN that could be testable?

    BBN is a big subject, but so far predictions look very similiar to standard BBN.

    3. On a theoretical note, why do you relate a particle’s rest energy to the gravitational potential of the Universe?

    I didn’t ask it to, but when you calculate a particle’s potential compared to everything else in the Universe, it comes out as U = -mc^2. We then have E + U = 0.

    4. What test can be done to verify that either c or h is changing as you advocate?

    If you had an accurate enough clock, you could measure c change in the lab. So far the best tests are redshift of Type Ia supernovae, (1 + v/c)/sqrt[(1 - (v/c)^2], solar energy production E = mc^2, and laser distance to the Moon dr = cdt. These are chosen because they measure c independent of h. All three show that c is slowing according to GM = tc^3.

    5. How do you reconcile this with the temperature of the cosmic microwave background being what it is? Based on your equations, the Rydberg, or the energy for ionizing a hydrogen atom from its ground state, is time variable, scaling as t^(-2/3). So if photon energies are no different than they are in standard cosmology but the energy to ionize hydrogen scales as t^(-2/3), the Universe should not have recombined when it did. Energies for the hydrogen atom should have been different by a factor of 1000 at a time t=380,000 years. The hydrogen atom is well-studied and well understood; so is the physics of the CMB. How does this add up in your theory?

    If the Ryberg R ~ t^{-2/3}, then the wavelengths scale as t^{2/3} along with scale factor R, Schwarzhild radius and the scale of magnetic fields. As you know, redshift of distant galaxies is caused not by their running from us but by their wavelengths expanding proportional to scale factor R.

    Interesting that binding energy may increase as E ~ t^{-2/3} Potential would then also scale as U ~ t^{-2/3} so again E + U = 0. This is almost certainly not enough to answer you, but more will be posted in the future.

  18. #18 Yoyo
    May 5, 2008

    I’d like to add a question for Louise.

    In description of your metric, why do you deliberately choose r = ct and GM = tc^3 so that your metric has signature (-1, -1, -1, -1)? This is (obviously) not Lorentzian.

  19. #19 Yoyo
    May 5, 2008

    (sorry, link screwed up)

    I’d like to add a question for Louise.

    In the description of your metric, why do you deliberately choose r = ct and GM = tc^3 so that your metric has signature (-1, -1, -1, -1)? This is (obviously) not Lorentzian.

  20. #20 ethan
    May 5, 2008

    Louise,
    I was hoping you’d address the physics issues I raised, perhaps I need to be more specific.
    1. The formula for the spin-flip transition, which you can find here, http://scienceworld.wolfram.com/physics/HydrogenSpin-FlipTransition.html, is proportional to hc2, which should change over time. But we don’t observe a change over time, just the expected scaling with redshift. How do you reconcile that?
    2. While BBN is a complex subject, standard BBN is a simple calculation that they teach you how to do in first-year graduate courses in astronomy/astrophysics. See the books by Kolb & Turner, or Peacock. If you go through chapter 9 of Peacock, with your time-varying formulas thrown in (especially section 9.5), you get very different abundances for helium-4 as well as very different physics for neutron decay. The Helium-4 mass fraction is known to be about 24% +/- 1%; if you can’t reproduce that, your theory is invalid.
    3. I mean, why do you take the Newtonian gravitational potential, -GmM/r, and apply it to a sphere of radius R=ct and call that the gravitational potential of the Universe?
    4. If you want to explain supernova expansion rates like this, then that’s fine. But the solar output is not consistent with time-varying c, nor is the Earth-Moon distance. The solar output is explained by simple stellar evolution and nuclear reaction rates; we have data on too many stars to throw a time-varying c in there. The Earth-Moon distance is increasing due to exchange of angular momentum; Mars’ Moons demonstrate that a time-varying c is inconsistent with their motion, as does the Earth-Sun distance.
    5. Again, CMB, tightly constrained. Can you reproduce this?
    I think questions 1, 2, 4, and 5 are the really important ones here, and they need to be addressed for your theory to demonstrate its validity.

  21. #21 L. Riofrio
    May 12, 2008

    Neil Turok, who is a bigger critic of inflation than I, has just been appointed director of Perimeter Institute. I recommend that you crank out a blog post saying Turok didn’t get the memo. Don’t forget the warning “crazy stuff here.” Then again, it seems easier to pick on the girl.

  22. #22 ethan
    May 12, 2008

    Turok has always been a critic of inflation. I would’ve thought he would’ve jumped on-board after COBE, because his model of cosmic strings predicted very different low multipoles of the CMB than was predicted by inflation. The observations matched with inflation. Then he and Steinhart came out with their bizarre ekpyrotic model and they’ve been trying to come up with alternatives ever since.
    Coming up with alternatives is a good thing. Clinging to models that conflict with observations isn’t. I’m not picking on you; I’m picking on your science. And you’re not defending it.

  23. #23 Yoyo
    May 12, 2008

    Ethan wrote: “I’m picking on your science. And you’re not defending it.”

    You’re not kidding Ethan. She’s also convinced she’s being picked on because she’s a woman.

    I’ve asked Louise
    several
    very simple mathematical questions her derivation and she’s repeatedly ignored them, or responded with the answer to a question I didn’t ask. She has no answer as to why her $R(t) = ct$ has dimensions of length when it should be dimensionless, and it’s clear she doesn’t actually know what the metric (or even the signature) of her spacetime actually is.

    A summary here. I don’t see any point in pursuing this further. Louise is obviously not interested in an open discussion.

  24. #24 ömer coşkun
    March 5, 2011

    Well, I’ll leave Louise to answer these particular questions, as she has done previously, but note that 3. is particularly interesting. Those of us who see something in this cosmology, eg. Pitkanen, have different interpretations of 3. It goes back to Mach’s ideas of inertia, which strongly motivated Einstein, but could not be incorporated properly into GR due to the strictly local nature of Riemannian geometry. In a modern context, I like to begin by picturing a beam of mixed charged leptons in a mass spectrometer, where inertia splits the beam into 3. This treats rest mass as a quantum number and Mach’s principle is elevated to a holographic one, which is very similar to what some string theorists have in mind.