Why all these prejudices against a constant? ( dark energy is a fake probem)

[marcus]

smoit #56, are you saying that for the 10-dimensional SO(16) x SO(16) heterotic string, you can get the observed cosmological constant by assuming a physically reasonable supersymmetry scale? If so, could you then look for a way to compactify six dimensions without adding to the vacuum energy?

Heh heh, yes Smoit. Will you now explain the value of the observed cosmological constant by assuming a 10D string theory?

So far no one has responded to what I quoted from Liberati et al. He is a highly respected QG phenomenologist, not specifically associated with anyone approach Loop or other. I quoted from the FLS paper (Finazzi, Liberati, Sindoni) in post #34
https://www.physicsforums.com/showthread.php?p=3503823#post3503823
Anybody have any direct response to FLS points?

As a reminder, here are excerpts from their conclusions---please go back to #34 to see the full passage:

==quote FLS http://arxiv.org/abs/1103.4841 ==
...The implications for gravity are twofold. First, there could be no a priori reason why the cosmological constant should be computed as the zero-point energy of the system. More properly, its computation must inevitably pass through the derivation of Einstein equations emerging from the underlying microscopic system. ...

... In this respect, it is conceivable that the very notion of cosmological constant as a form of energy intrinsic to the vacuum is ultimately misleading. ... the reasoning of this Letter sheds a totally different light on the cosmological constant problem, turning it from a failure of effective field theory to a question about the emergence of the spacetime.
==endquote==

 

[Fra]

There is no known natural way to derive the tiny cosmological constant that plays a role in cosmology from particle physics
...
it means that there is something we do not understand yet in particle physics. What could this be?[/INDENT]

I share this stance.

I'll just want to add that just because there is something we do not yet understand about particles physics (which btw, I think is that QFT formalism simply isn't a ther cosmoloical measurement theory we need due to referencing infinitely massive observers) doesn't exclude there is ALSO sometihng we do not yet understand about gravity.

This seems very much rooted in the konwn issue of observables. I agree with Marcus that to expect a "QFT explanation" of cosmological expansion with QFT as it stands makes not sense IMO. All of QM/QFT is devised as a measurement theory - against a fixed context. This context is either classical reality, or some boundary at infinity where one collects S-matrix data. Of course in classical reality, the background metric is attached to the observer frame. The problem is that all of that makes sense only in special cases. Not in the most general QG domain since all the qualifiers break down.

I think the challange is to find the new framework that extends measurementtheory to cosmological scenarios; first THEN does it make snse to try to see how gravity fits in the corrected picture. This as I see it certainly must included serious reworking on QM&QFT foundations.

/Fredrik

 

[smoit]

smoit #56, are you saying that for the 10-dimensional SO(16) x SO(16) heterotic string, you can get the observed cosmological constant by assuming a physically reasonable supersymmetry scale? If so, could you then look for a way to compactify six dimensions without adding to the vacuum energy?

I don't know! Indeed, the value one gets is a mere coincidence since it's a value for the vacuum energy in 10D. Indeed, assuming M_SUSY~(TeV)~10^-15M_Plank and M_string~M_Planck one gets Str(M_SUSY⁸)M_string²~10^-120M_Planck¹⁰.

As I said before in #56, if you want to compute the CC in a realistic compactification you first need to compute the string spectrum in such a background, i.e. a background that reduces to some N=1 D=4 SUGRA with spontaneously broken SUSY, and then compute the partition function. Again, you'll have not only the zero modes (SUGRA modes) but also an infinite tower of stringy modes, both momentum and winding, plus an infinite tower of various KK modes all contributing to the CC. It would be interesting if one could do this even for a simple, say orbifold, compactification. All I was saying was that quoting the SUGRA result where the first non-vanishing supertrace contribution is quadratic in the cutoff means nothing as this is just a computation in an effective 4D QFT, which is missing an infinite number of contributions, which may alter the result completely. The point is that at such short distances the theory effectively becomes 10 dimensional and no longer just a QFT and the CC computation is UV-sensitive so I'm raising a speculation that this may ultimately address the perturbative quantum part of the problem. There may also be various non-perturbative contributions as well as tree-level pieces, and that's what makes the whole problem so tricky.

 

[smoit]

In other words, it is a mistake to identify the cosmological constant λ with the zero point energy Λ of a QFT, for the same reason one should not a priori identify the charge of the electron with its radiative corrections​

No sane particle theorist makes such an identification, Markus! Read the Polchinski reference and you'll see that nowhere does he identify the cosmological constant only with the zero point energy. On the contrary, as people have repeatedly said here, the CC receives all kinds of tree-level, perturbative and non-perturbative contributions and the observed tiny value includes of all of them.

 

[marcus]

Good, so you agree with Bianchi Rovelli on that point! You quoted part of what they said on page 6 although it looks like you attributed it to me.

They say it is a mistake to identify the cosmo constant with the QFT zero point energy, and you obviously agree since you claim that no sensible particle theorist would confuse the two.

So now we can go on to the next step in their argument, which continues on page 7. They start by pointing out that vacuum energy by itself does not gravitate, only shifts/differences do, not the zeropoint itself. We all know this--I'm sure you agree with the next passage, however simply for completeness I recap:

An effect commonly put forward to support the “reality” of such a vacuum energy is the Casimir effect. But the Casimir effect does not reveal the existence of a vacuum energy: it reveals the effect of a “change” in vacuum energy, and it says nothing about where the zero point value of this energy is. In fact, simple physical arguments indicate that the vacuum energy, by itself, cannot be “real” in the sense of gravitating: if it were, any empty box containing a quantum field would have a huge mass, and we could not move it with a force, since gravitational mass is also inertial mass. On physical grounds, vacuum energy does not gravitate. A shift in vacuum energy does gravitate. This is nicely illustrated by an example discussed by Polchinski in [3]:...​

There is the Polchinski reference you mentioned! I am glad to see you are reading ahead, Smoit. Now we come to the next step in their argument. Let's consider it together, maybe you will find a flaw and point it out to me. Now we are on page 7.

Why does standard QFT have so much trouble adjusting to this straightforward physical fact? We do not know the answer, but there is a general consideration that may be
relevant: in which theoretical context is formulated the argument for large radiative corrections to λ? If it is in a context in which we disregard gravity, then a large vacuum energy is physically irrelevant, because the λ term in the action (14) couples only to the gravitational field g, and is invisible if we disregard gravity. The next option is...

...But then there is a catch: if λ is different from zero, then (φ ,η) is not a solution...​

And so they go down the list of ways to address QFT's problem. Trying different theoretical contexts. This I think is the heart of their argument. See what you think.

 

[smoit]

They say it is a mistake to identify the cosmo constant with the QFT zero point energy, and you obviously agree since you claim that no sensible particle theorist would confuse the two.

What audience are they addressing in their paper? Undegraduates who just had a quantum mechaniscs class and learned about the zero-point energy? What is it that's new in their paper that particle theorists did not know already?

What I and many people have already said here is that apart from the perturbative piece, the CC contains several other types of contributions - tree-level and non-perturbative. Why is this so hard to grasp?

 

[smoit]

An effect commonly put forward to support the “reality” of such a vacuum energy is the Casimir effect. But the Casimir effect does not reveal the existence of a vacuum energy: it reveals the effect of a “change” in vacuum energy, and it says nothing about where the zero point value of this energy is. In fact, simple physical arguments indicate that the vacuum energy, by itself, cannot be “real” in the sense of gravitating: if it were, any empty box containing a quantum field would have a huge mass, and we could not move it with a force, since gravitational mass is also inertial mass. On physical grounds, vacuum energy does not gravitate. A shift in vacuum energy does gravitate. This is nicely illustrated by an example discussed by Polchinski in [3]:...​

This "simple argument" is obviously flawed since an empty box containing all quantum fields in our vacuum already contains ALL contributions - tree-level and quantum, which all add up to the tiny value. There is no experiment that I'm aware of where one can separate the total tree-level contribution to the CC from the total quantum contribution to the CC. Only if someone could magically switch off the tree-level piece and the mass of the "empty" box would still be tiny, would one be able to claim that the zero-point energy does not contribute much to the inertial mass.

The Casimir effect clearly shows that the quantum contributions, which we can compute and measure do, in fact, gravitate and I definitely agree with Polchinski. Every quantum field contribution produces an upward (for bosons) or downward (for fermions) shift in the vacuum energy. The Casimir effect clearly indicates that such individual quantum contributions do gravitate and once they are all added up the total zero-point energy should still gravitate, unless one has exact supersymmetry and they all precisely cancel.

 

[marcus]

One might say this to a QFT'er. You have a 120 order of magnitude problem in YOUR theory. It is not GR's problem. If you think you can fix it with some of the dodges Smoit mentioned, go for it and good luck to you! So far we don't see it getting fixed by those means, however.

On the other hand if you really want a quantum gravity fix, then be clear about it. You are going to have to move QFT out of the Minkowski context, and you will ultimately have to rebuild QFT on a quantum geometry basis, e.g. LQG.

 

[smoit]

So far we don't see it getting fixed by those means, however.

We? Meaning all the retired mathematicians who post on the physics forum?

 

[marcus]

We? Meaning all the retired mathematicians who post on the physics forum?

Yes Mr. Smolin-and-Woit and despite a bt of sarcastic snarling and grumbling we and our like are legion.

But in fact when I said "we" I was interpreting from the passage from Bianchi and Rovelli that I quoted in post #65:

"Why does standard QFT have so much trouble adjusting to this straightforward physical fact? We do not know the answer, but ..."

 

[marcus]

Since we are discussing the argument on page 7 of the Bianchi Rovelli paper, I should give the link again:
http://arxiv.org/abs/1002.3966
Why all these prejudices against a constant?
Eugenio Bianchi, Carlo Rovelli
(Submitted on 21 Feb 2010)
The expansion of the observed universe appears to be accelerating. A simple explanation of this phenomenon is provided by the non-vanishing of the cosmological constant in the Einstein equations. Arguments are commonly presented to the effect that this simple explanation is not viable or not sufficient, and therefore we are facing the "great mystery" of the "nature of a dark energy". We argue that these arguments are unconvincing, or ill-founded.
9 pages, 4 figures

An easy way to get the paper is simply to google "constant prejudices"
The arxiv link should turn up as the first or second hit.
Anyone coming in new would be well-advised to read the paper. It is easy to understand and puts the discussion here in a clearer light.

 

[smoit]

Since we are discussing the argument on page 7 of the Bianchi Rovelli paper, I should give the link again:
http://arxiv.org/abs/1002.3966
Why all these prejudices against a constant?
Eugenio Bianchi, Carlo Rovelli
(Submitted on 21 Feb 2010)

FYI, after almost 2 years, the authors have so far failed to publish it in a refereed journal.

 

[Harv]

The Casimir effect clearly shows that the quantum contributions, which we can compute and measure do, in fact, gravitate

But we can't verify the coupling of gravity directly to the individual loops involved in these quantum contributions.

 

[smoit]

But we can't verify the coupling of gravity directly to the individual loops involved in these quantum contributions.

The shift in the electrostatic energy due to vacuum polarization (experimentally measured in the Lamb shift) contributes an amount large enough that, in case if it did not gravitate, would violate the equivalence principle to a precision of one part in a million. However, we can experimentally verify the equivalence principle to a precision of one part in 10¹² and therefore these loops must couple to gravity.

 

[Fra]

The shift in the electrostatic energy due to vacuum polarization (experimentally measured in the Lamb shift) contributes an amount large enough that, in case if it did not gravitate, would violate the equivalence principle to a precision of one part in a million. However, we can experimentally verify the equivalence principle to a precision of one part in 10¹² and therefore these loops must couple to gravity.

I'm not sure if you refer to some new experiments I'm unaware of but I think it's still important to note which domains to theory space where certain "principles" are tested. Ingoring that is one of the things I find most disturbing, extrapolations of "evidence" into new domains are often made without much argument. This is exactly what people also do with things that are well tested for PARTICLE physics which usually means the observer is in a classical laboratory and the system is a very small subsystem. Inferences from such situations just don't generalize to cosmological scenarios. This fact is often ignored on grounds that "such extrapolations worked in the past".

I suspect the 10^12 test you refer to is the classical mechanics test of the torsion pendulum, right?

If there really experiments made that verifies the equivalence principle for actual lamb shift, that would be news for me. I think it's in principle testable, but the problem is as far a I know that the gravitational field on Earth is too weak to yield much of a significant possibility to test it here?

But I do not follow all new experiemtns, if someone konws of an actual test of the equivalence principle for lamb shifted systems I would be interested to read about how the experiment was conducted. I have seen some old papers where it was "in principle testable" was devicded, but the conclusion was that in practice it wasn't becaues hte gravity on Earth is so weak.

I'm not sure if some astronomic observations of lambshifted systems near more massive bodies is possible? I'm not sure how that would be done.

/Fredrik

 

[smoit]

@Fra, Here is a reference that is the most referred in the literature but you'd have to go to your library to actually read it: http://slac.stanford.edu/spires/find/hep/www?irn=6818293

Please, read very carefully what I said in my previous comment b/c your response indicated that you had misunderstood it.

 

[Harv]

The shift in the electrostatic energy due to vacuum polarization (experimentally measured in the Lamb shift) contributes an amount large enough that, in case if it did not gravitate, would violate the equivalence principle to a precision of one part in a million. However, we can experimentally verify the equivalence principle to a precision of one part in 10¹² and therefore these loops must couple to gravity.

I looked at Polchinski's paper and understand now why you're right. Thanks.

 

[smoit]

@Harv, no problem! Joe's article is good and pretty much sums up the current situation. I saw his talk on this topic at KITP back in 2006, you can find it here if you're curious: http://online.itp.ucsb.edu/online/strings_c06/polchinski/

 

[Haelfix]

I'd say that the CC problem is definitely a UV problem because we are dealing with a highly relevant operator so you cannot ignore all the extra degrees of freedom arising in the UV.

Yea tis true, that's why I qualified my statement. For the nonexperts, what this means in practise is that you need to know all the fields and matter all the way up to the Planck scale, as they will all contribute (naively increasing in magnitude, not necessarily in sign) contributions to the total constant. You can't ignore them. This is also why no first principles solution to the problem exists and probably never will exist (absent the discovery of some highly constraining mechanism or symmetry).

However I think I am correct in pointing out that the apparent magnitude of the problem occurs b/c of the scales mismatch, which is essentially set by the infrared physics.

where the first non-vanishing term is quadratic in the cutoff, the first non-vanishing contribution to the 10D vacuum energy comes at order Str(M8SUSY)M2string, where MSUSY is the scale of SUSY breaking.

Yep that's interesting, but I don't quite understand these constructions. What is MSusy specifically here (is it arbitrary)? Also, why wouldn't the mechanism that generates these nonperturbative corrections at the low energy scale (in the language of the effective field theory) not also generate unwanted and observable KK states?

As far as numerology goes. I like the following two observations as well. If you take the cutoff to be the mass of the lightest neutrino, the scales match. Another weird coincidence... The supersymmetry breaking scale seems to be exactly halfway (on a logarithmic scale) between the vacuum energy scale and the Planck scale. Why?

 

[smoit]

Yep that's interesting, but I don't quite understand these constructions. What is MSusy specifically here (is it arbitrary)? Also, why wouldn't the mechanism that generates these nonperturbative corrections at the low energy scale (in the language of the effective field theory) not also generate unwanted and observable KK states?

By M_SUSY I just denoted a generic scale of level spacing. Its value should be related to the string scale, I think, since SUSY is broken at the string scale in this construction.
That's why I did not really want to identify M_SUSY with the scale obtained in some 4D EFT from the soft breaking but the numerology looks cute
You probably mean perturbative instead on non-perturbative, right? This computation is in 10D, so there are no KK states involved. That said, at such extremely short distances even in a compactified 4D vacuum all the KK modes become light and the theory does effectively become 10 or maybe 11 dimensional. I think that what one really needs here for a realistic computation is to translate soft SUSY breaking in some 4D EFT into the splittings in the entire string spectrum and then compute the one-loop partition function. My hunch is that the scale of the boson-fermion splitting in the string levels would be related to the gravitino mass scale instead of the string scale and the result of the computation may actually give the correct order of magnitude. What was really neat for me to learn was that the finiteness of the CC in a non-tachyonic non-SUSY string theory is guaranteed by the modular invariance, despite the presence of an infinite tower of contributions in the UV. Here is a nice reference where you can read about these ideas: http://arxiv.org/PS_cache/hep-th/pdf/9503/9503055v2.pdf

 

[Fra]

@Fra, Here is a reference that is the most referred in the literature but you'd have to go to your library to actually read it: http://slac.stanford.edu/spires/find/hep/www?irn=6818293

Please, read very carefully what I said in my previous comment b/c your response indicated that you had misunderstood it.

Smoit thanks for the link. I haven't read it but that indeed looks like the classical paper I also thought you meant. It could well be that I didn't get your point at all, in that case I'm sorry.

Anyway my point was this: That paper tests WEP to one part in 10^12, but it's all classical mechanics (torsion balance) and relatively speaking macroscopic classical systems (which is dominated by baryonic mass) with classical measurements.

Thus I question the validity of that test when applied to situations where the classical mechanics framework just don't hold. Also just as a ballpark number it seems the contribution of lamb shift to the classical level mass is the order of 1 in 10^15 or so? Which seems to be beyond hte level os current experimental tests?

So I didn't quite get how that classical mechanics test of WEP for 1 part in 10^12 gives any information about the the nature loop corrections in general (which then of course goes outside classical mechanics)?

Perhasp I'm missing something, could you explain?

/Fredrik

 

[Fra]

Trying to make sure I understand the logic, let me know if I get it wrong:

such individual quantum contributions do gravitate and once they are all added up the total zero-point energy should still gravitate

Are you suggesting that (when considering the origin of mass) since the idea is that the actual classical masses (such as those in the 1971 torsion balance experiment) are largely made up of confined energy such as confined virtual gluons etc, therefore the conclusion is that all such "virtual energies" as infered by all observers(?) must contribute equally to both inertial and gravitatonal mass?

/Fredrik

 

[smoit]

Also just as a ballpark number it seems the contribution of lamb shift to the classical level mass is the order of 1 in 10^15 or so? Which seems to be beyond hte level os current experimental tests?

I'm not sure where you obtained this ballpark number. I suggest you read page 3 in "arxiv.org/PS_cache/hep-th/pdf/0603/0603249v2.pdf"[/URL].

[quote="Fra, post: 3620485"]
So I didn't quite get how that classical mechanics test of WEP for 1 part in 10^12 gives any information about the the nature loop corrections in general (which then of course goes outside classical mechanics)?

Perhasp I'm missing something, could you explain?

/Fredrik[/QUOTE]

If you are questioning how one can measure quantum effects by classical means than you should read a book or take a class in quantum mechanics. The whole reason for inventing quantum mechanics in the first place was the experimental results which could not be explained by classical physics, e.g. the discrete atomic spectra, etc. It seems as though you are questioning the ability to measure quantum effects by classical instruments and I suggest that you simply create a separate thread with the appropriate title to carry on the discussion there.

 

[smoit]

Trying to make sure I understand the logic, let me know if I get it wrong:


Are you suggesting that (when considering the origin of mass) since the idea is that the actual classical masses (such as those in the 1971 torsion balance experiment) are largely made up of confined energy such as confined virtual gluons etc, therefore the conclusion is that all such "virtual energies" as infered by all observers(?) must contribute equally to both inertial and gravitatonal mass?

/Fredrik

I said nothing about virtual gluons and their contributions to the rest mass of baryons b/c I didn't want to get into discussing lattice QCD results for hardon masses but yes, virtual gluon loops do contribute a significant portion of a baryon's inertial mass and such effects are much more significant than the virtual photon loops Polchinski talks about.

 

[RUTA]

I read the Bianchi & Rovelli paper as well as Chap VIII.2 “The Cosmological Constant Problem and the Cosmic Coincidence Problem” in Zee, Quantum Field Theory in a Nutshell, Princeton Univ Press, 2003 (p 434). I do not find any disagreement regarding the facts, only their reactions thereto. For example:

B&R write, “But to claim that dark energy represents a profound mystery, is, in our opinion, nonsense.” In contrast, Zee introduces this subject by saying, “I now come to the most egregious paradox of present day physics.”

Regarding the coincidence problem, B&R write, “it is quite reasonable that humans exist during those 10 or so billions years (sic) when \Omega_b and \Omega_\Lambda are within a few orders of magnitude from each other.” In contrast, Zee writes, “the epoch when \rho_M \sim \Lambda happens to be when galaxy formation has been largely completed. Very bizarre!”

Both agree that (per B&R) “There is no known way to derive the tiny cosmological constant that plays a role in cosmology from particle physics. And there is no understanding of why this constant is not renormalized to a high value.” B&R’s reaction to this fact is, “But this does not means (sic) that there is something mysterious in the cosmological constant itself: it means that there is something we do not understand yet in particle physics.” While Zee writes, “But Nature has a big surprise for us. While theorists racked their brains trying to come up with a convincing argument that \Lambda = 0 observational cosmologists steadily refined their measurements and recently changed their upper bound to an approximate equality \Lambda \sim (10^{-3} \mbox{ev})^4! The cosmological constant paradox deepens.”

In short, the B&R paper merely argues for a particular emotional reaction to the situation regarding the cosmological constant in physics and cosmology. I would be surprised to see this paper published in a physics journal, since it does not expand upon our knowledge of physics. However, the paper’s use of a timely topic to highlight one aspect of our failure to unify the Standard Model with gravity is not without value. I could see this included in the proceedings for a philosophy of science symposium, for example. It would also be appropriate for a pedagogical journal in physics. It certainly motivated me to look more deeply into the issue. Thanks for posting this, marcus.

Edit: I'm trying to figure out how to use TeX in PF. Obviously, I haven't found an "in line" tex command yet.

 

[juanrga]

The cosmological constant becomes a mistery as soon as you do not write it on the left hand = "the gravity" side of the equations

R_{\mu\nu} - \frac{1}{2} g_{\mu\nu} R + \Lambda g_{\mu\nu} = \frac{8\pi G}{c^4}T_{\mu\nu}

but it you write it on the right hand = "the matter" side.

R_{\mu\nu} - \frac{1}{2} g_{\mu\nu} R = \frac{8\pi G}{c^4}T_{\mu\nu} - \Lambda g_{\mu\nu}

In vacuum (with T=0) you still have some kind of "matter" which affects spacetime:

R_{\mu\nu} - \frac{1}{2} g_{\mu\nu} R = - \Lambda g_{\mu\nu}

If you leave this term on the left hand side, the question where it comes from and why it is there, is still open, but it is not a qustion about matter, dark energy or something like that; it is a question about gravity.

Sorry but a mystery does not disappear by moving a term, from the right to the left, on the same equation.

R_{\mu\nu} - \frac{1}{2} g_{\mu\nu} R = - \Lambda g_{\mu\nu}

is just so problematic as

R_{\mu\nu} - \frac{1}{2} g_{\mu\nu} R + \Lambda g_{\mu\nu} = 0

 

[marcus]

Sorry but a mystery does not disappear by moving a term, from the right to the left, on the same equation.

R_{\mu\nu} - \frac{1}{2} g_{\mu\nu} R = - \Lambda g_{\mu\nu}

is just so problematic as

R_{\mu\nu} - \frac{1}{2} g_{\mu\nu} R + \Lambda g_{\mu\nu} = 0

Wait Juan I don't think you grasped Tom's point! It is quite a valid one if you are familiar with the custom in General Relativity of writing the equation geometry (e.g. curvature terms) on the left and matter terms on the right.

Lambda is a curvature constant and occurs naturally and unsurprisingly in the geometry LHS
(since as Einstein observed early on, it is allowed by the symmetries of the theory).

You only make a puzzle out of it if you consider this natural curvature term to be "matter", and symbolize this by moving it to the RHS of the equation.

If you make this mistake then you baffle your self with asking "Now what could this matter be?!"

As Tom pointed out the constant curvature term Lambda is analogous to a constant of integration---that you are taught in beginning Calculus class to put in the answer when you integrate. It must be there because it is allowed by the conditions of the problem.

 

[marcus]

...
In short, the B&R paper merely argues for a particular emotional reaction to the situation regarding the cosmological constant in physics and cosmology. I would be surprised to see this paper published in a physics journal, since it does not expand upon our knowledge of physics. However, the paper’s use of a timely topic to highlight one aspect of our failure to unify the Standard Model with gravity is not without value. I could see this included in the proceedings for a philosophy of science symposium, for example. It would also be appropriate for a pedagogical journal in physics. It certainly motivated me to look more deeply into the issue. Thanks for posting this, marcus.

I think B&R state clearly at the outset that their purpose is to debunk the hype. The paper is aimed at fellow physicists who describe the "cosmological constant problem" in exaggerated language.

They give some examples of this near-hysterical rhetoric right the start of the paper. That is clearly the target.

I think that too much hype tends to damage the prestige and credibility of physics. Physicists have been shouting "wolf" or "fire" or "recreating the big bang" and "theory of everything!" so much that the educated audience has gotten into the habit of discounting what they say as attention-getting rubbish.

Since the intended audience of the paper is other physicists, particle physicists primarily I would say, I can't imagine why they would want to publish it in a philosophical or pedagogical journal. It is a warning to tone down the exaggerated rhetoric.

As such, the arxiv is a good place to post it. Or else possibly in the opinion section of a magazine like Physics Today. It's not a research or review article, after all. But why bother, since arxiv is already a perfect outlet?

I was amused by Smoit pointing out that the article had not been published in a peer-review journal, as if this were a criticism. Rovelli has over 14,000 cites to his over 200 professional articles. He hardly needs to try to peer-publish everything he writes to bolster his trackrecord. Since this piece is primarily advice to fellow physicists to sober-up and cut the hype for the good of the field, I actually doubt it has been submitted anywhere. Arxiv is the perfect place to reach those who are able to get the message.

 

[RUTA]

Zee's response to the facts presented in his text and B&R's paper is that they constitute "the most egregious paradox of present day physics." Why would B&R expect to change that reaction by simply rehashing what is known? Therefore, I would say this paper can only expect to find a sympathetic audience among those not familiar with the technical aspects of the issue, i.e., it's a pedagogical piece.

 

[simplicial]

Some other comments on the dark energy problem.

http://www.nature.com/nature/journal/v466/n7304/full/466321a.html

NATURE | NEWS AND VIEWS
Cosmology forum: Is dark energy really a mystery?
Bianchi, Rovelli, Kolb

Nature 466, 321–322 (15 July 2010)
doi:10.1038/466321a

The Universe is expanding. And the expansion seems to be speeding up. To account for that acceleration, a mysterious factor, 'dark energy', is often invoked. A contrary opinion — that this factor isn't at all mysterious — is here given voice, along with counter-arguments against that view.