David Gross discusses some experience with a double-faced Lee Smolin - concerning AdS/CFT and background independence - in their discussion with journalist George Johnson. It was the very first public video from which the laymen could learn that the top physicists consider Lee Smolin to be a (now I quote George Johnson) "crackpot" - a fact that would be completely hidden if the information only depended on the journalists.

More worrisome and persistent stories are often told by A.S., A.V., R.B., and many other big shots.

But what he's doing and saying after the Fermi collaborations have proved that all the "theories" he has ever invented about quantum gravity were rubbish simply exceeds all the limits that could be tolerable for a person who should be allowed to freely walk on the street.

After many years when he was boasting about his "falsifiable predictions" of loop quantum gravity (Lee has even become a template for Leslie Winkle in an award-winning sitcom) that were moreover completely "generic", and when he was using these "predictions" to sling mud on the top research in high-energy physics, namely string theory, he has turned his coat.

Quite suddenly, everything is different. There have never been any predictions, he says. Let's compare what he said about loop quantum gravity e.g. for edge.org and what he's writing these days ("That Proton From GRB090510"). Edge.org:

When we first worked out the predictions for these smallest units of area and volume, we had no idea that they would be observable in real experiments in our lifetime. However, a number of people—beginning with Rodolfo Gambini, of the University of the Republic in Montevideo, and Jorge Pullin, then at Penn State—showed that there are indeed observable consequences. At about the same time, Amelino-Camelia and others were pointing out that if there were such effects, they would be detectable in experiments involving cosmic rays and gamma-ray bursts. These effects are caused by light scattering off the discrete structure of the quantum geometry, analogous to diffraction and refraction from light scattering off the molecules of the air or liquid it passes through. The quantum gravity effect is tiny—many orders of magnitude smaller than that due to matter. However, we observe light from gamma-ray bursts—huge explosions, possibly caused by mergers of binary neutron stars or black holes—that has traveled across the universe for some 10 billion light-years. Over such long distances, the small effects amplify to the point where they can be observed. Because elementary particles travel as waves in quantum theory, the same thing happens to such particles—protons and neutrinos, for example. It is possible that these effects may be responsible for the surprises I mentioned in the observations of very-high-energy cosmic rays.Today:

Now, here is the really interesting part: Some of the effects predicted by the theory appear to be in conflict with one of the principles of Einstein's special theory of relativity, the theory that says that the speed of light is a universal constant. It's the same for all photons, and it is independent of the motion of the sender or observer.

How is this possible, if that theory is itself based on the principles of relativity? The principle of the constancy of the speed of light is part of special relativity, but we quantized Einstein's general theory of relativity. Because Einstein's special theory is only a kind of approximation to his general theory, we can implement the principles of the latter but find modifications to the former. And this is what seems to be happening!

So Gambini, Pullin, and others calculated how light travels in a quantum geometry and found that the theory predicts that the speed of light has a small dependence on energy. Photons of higher energy travel slightly slower than low-energy photons. The effect is very small, but it amplifies over time. Two photons produced by a gamma-ray burst 10 billion years ago, one redder and one bluer, should arrive on Earth at slightly different times. The time delay predicted by the theory is large enough to be detectable by a new gamma-ray observatory called GLAST (for Gamma-ray Large Area Space Telescope), which is scheduled for launch into orbit in 2006. We very much look forward to the announcement of the results, as they will be testing a prediction of a quantum theory of gravity.

Hi,Wow.

I wonder if I could clarify some issues raised here. More details and references are in a recent paper by Amelino-Camelia and myself in arXiv:0906.3731.

First, LQG in 3+1 dimensions has not been shown to break or deform Lorentz invariance. There were some papers, starting in the 90s, studying excitations of non-physical ansatz’s for vacuum states (ie that didn’t satisfy the quantum constraints) that showed evidence for Lorentz symmetry breaking. These were not prediction of LQG, they were consequence of an ansatz for the ground state that broke both Lorentz invariance and diffeomorphism invariance. They could be characterized as exploratory, but very far from definitive. There is no definitive result concerning the symmetry of the ground state in LQG in 3+1 dimensions.

So, unfortunately, it is not correct to claim that this or any such result rules out LQG. I say unfortunately because it would be nice if we knew what the prediction was of LQG for deformed dispersion relations, but despite some effort we don’t.

I have published two papers arguing that a form of DSR is a consequence of generic quantum theories of gravity in the semiclassical approximation, plus certain scaling assumptions: hep-th/0501091v2, arXiv:0808.3765v1. These derivations make several assumptions, particularly as to the scaling dimensions of certain operators, which have not been confirmed in LQG or any theory. If there is no linear dispersion (order l_Planck) then we learn that one of the assumptions of these arguments are wrong, and my guess is it would be these scaling assumptions.

One can also deduce the significance of these scaling relations from some general considerations that derive kappa Poincare symmetry from quantum deformed (A)dS symmetry, this was shown in hep-th/0306134 and hep-th/0307085.

In fact, in 2+1 dimensions the argument from quantum group theory is correct and the low energy symmetry is kappa-Poincare (hep-th/0512113, hep-th/0502106). This suggests its not crazy that to hypothesize that the same is true in 3+1 but this is not a proof, it is a suggestion of a line of argument.

Whether string theory allows deformed Poincare symmetry is unknown, in hep-th/0401087, Magueijo and I showed that there are consistent free bosonic string theories with deformed energy-momentum relations, to my knowledge no one has followed up to investigate what happens to this when interactions are included. Otherwise string theory assumes perfect Lorentz invariance.

Further, Lorentz symmetry breaking at order l_Pl is already ruled out by several orders of magnitude by observations of polarized radio galaxies which constrain the bi-frengence from the parity odd term in the effective action for Maxwell fields that appears at dimension five. What might be the case, but is now somewhat constrained, is parity even deformation of Poincare invariance. It also should be emphasized that order l_Pl^2 effects are not strongly constrained by any observation so that there could still be Planck scale Lorentz symmetry breaking at that order.

Coming to the recent observations, that Fermi was capable of putting order L_Pl limits on dispersion has been clear for a while and was discussed in detail by Amelino-Camelia and myself in arXiv:0906.3731. My reading of the recent Fermi collaboration paper on GRB090520 is that the conservative bound of about 1.2 M_Pl is reliable, while the stricter limits are based on assumptions about the sources which are at this time speculative. I might make a couple of other comments on the results in this important paper.

- -Even the most conservative bound > 1.2 M_{Pl} conflicts with the claims of Ellis et al in the Magic and subsequent papers to make a measurement of an effect of around .1 M_{Pl}.

-They also give a very interesting bound on the advanced case, s=-1 which is also around 1.2M_{Pl}. This is much better than the best bound so far which so far as I know is the one in Giovanni and my paper: 3.2 X 10^17 GeV .

Thanks,

Lee

Everyone who tolerates this disgraceful liar and demagogue as a part of the scientific community is an immoral bastard. Not only the internet writers about physics - I will omit the names - but also the very institutions whose official goal should be to support science actively do lots of things to protect this stunning degree of scientific misconduct.

Of course that what Smolin says doesn't influence real science because every competent scientist has known that Lee Smolin isn't a good physicist for years or decades. And it is damn easy to see and prove that similar discrete models of spacetime simply cannot preserve the Lorentz symmetry.

For example, the proper 2-areas in relativity may be both real and imaginary, so any theory that implies that they must be real is instantly falsified.

But what Smolin is doing is brutally influencing the laymen, including those who are behind various funding agencies and similar bodies. I urge everyone who has some responsibility for these matters to go after Smolin's neck.

And that's the memo.

Lubos, you're a funny man.

ReplyDeleteIn the first post you give, he speaks of the experimental test being one of the time delay between red and blue light. This is different from the dispersion relation, which he speaks of in the second post of his which you have copied. This second post actually comes from a different discussion: readers can see it in its full context at http://backreaction.blogspot.ca/2009/08/that-photon-from-grb090510.html.

ReplyDeleteThus, he does not contradict himself, and your claim is unjustified.

Your claims of him being a liar, demagogue, unethical, and immoral also hold no weight: where is the support for these claims?

Anyone who is reading this should consider that the claims of one person about another could be a reflection of the claimant's personality instead.

Sorry but you clearly don't understand basic physics. Red light and blue light may only arrive at different times if the group velocity depends on the frequency and the group velocity may only depend on the frequency if the phase velocity depends on frequency. To summarize, a different time of flight of different frequencies and dispersion is the same thing. You can't have one without the other.

ReplyDeleteHa ha ha, as I just read this article for the first time I knew that I know the name Giovanni Amelino Camelia from somewhere, it is the Italian Biker-Dude from BBC video about the smallness of scales ... :-D!

ReplyDeleteThe appropriate term describing the selfcontradictory behavior of one single guy illustrated in the blue and the red textbox is "Wendehals" in German ;-). A Wendehals always in real time adjusts the direction his nose points to in accordance with the prevailing wind direction ...

This article is immoral, I think

ReplyDeleteAhhh...poor little nerd. Feeling threatened so you must act out like an infant? You guys were so much funner when we were dumping apple sauce in your hair and laughing at your dungeons and dragons clubs.

ReplyDeleteWhen are you gonna realize no one cares about your star trek universe? We normal people live in reality while you live on a sheet of paper pretending its reality. Get out once in a while.

This explains why it is much more convenient to promote sufficiently generic ''theories'' like strings, so that they become unfalsifiable as a conceptual framework. Anyway, and in spite of Smolin boldness, it is really unclear to me if LQG is a falsifiable ''theory'' in general, since so little is known on its semi-classical limit which would constrain the possible candidates. I would very much appreciate that serious physicists stop claiming that their favorite ''theory'', may it be strings, loops or anything else, are (even theoretically) predictive, whereas deep inside they know it's not the case.

ReplyDeleteFrom all that I have learned from my study of psychology and my experience with human, I can very well say with utter confidence that the person who wrote the above article is concealing something. Maybe, he is lying or just misusing the facts.

ReplyDeleteLook at the strong wordedness of the article, and see that he doesn't give proper weightage to both the positive and negative sides.

I assume you're a troll "Luboš Motl", but in case that was genuine;

ReplyDeleteWe can all see that the author has a bit of venting he wants to do. But to question the claims of an article that is rife with defamatory and emotive language is actually not only wise but admirable. Many of the physical theories Smolin concerns himself with are highly speculative at this stage and it's simply not true that all "the top physicists consider Lee Smolin a crackpot."

I would encourage some genuine research into theoretical physics if you wish to continue holding these views with integrity. But you're clearly not gonna listen to me, so enjoy your swearing and physical high-horsery.

Reference TIME OUT OF MIND The Wrap BIG THINK NEWSWEEK Pakistan, August 2, 2013, it's annoying me that I have already put same ideas about the nature of time in my "TIME THEORY OF EVERYTHING", "A NEW THEORY OF THE UNIVERSE, MATTER AND ENERGY DO NOT EXIST", and "RETHINKING THE BASIC LAWS OF NATURE" in many different magazines, news papers, science and philosophy research forums available on line based on my original research. I am founding writer of TIME THEORY OF EVERYTHING. The theoretical physicist Lee Smolin examines the role of time in the universe on the same ideas in his book "Time Reborn" published April 23, 2013. Sorry to say, it is confirmed that why Lee Smolin is an immoral double-faced fraudster, liar and hardcore crackpot.

ReplyDeletehttp://motls.blogspot.com/2009/08/why-lee-smolin-is-immoral-double-faced.htmlReference)

Lee Smolin, in his book Time Reborn, did not bother to mention my name, which isn't morally a correct act.

Khalid Masood

Writer: "TIME THEORY OF EVERYTHING"

You're a real jerk.

ReplyDeleteI think the person who wrote this is a crank. And, very likely, an unpublished one. :)

ReplyDeleteWhy don't you worry about your own Theoretical arguments & advancements. Henceforth, with next to nill probability, you may, just maybe, one day, make a sound, structured, logical argument! As Mr. Smolin has accomplished!

ReplyDeletePlease note:

By a rotation of a cordinate system which I'll label: i, £. And £ in place of: (m=Ct). £=iCt. (Henceforth a vector is unchanged during rotation in a 4 cordinate transformation space) x^2' + y^2' +z^2' + £^2'

Tanθ= - ¡ B (that is) Cosθ= 1/ sqr (1-B^2) , Sin θ = -¡ B /sqr 1-B^2

The Lorentz Transformation can then be deduced after a few more steps for x' & £` or T'. And a rotation not in real, but yes, IMAGINARY can preserve the Lorentz Transformation!

°Weyl 1922 had also showed a very important more elongated aspect of preserving a cordinate transformation from IMAGINARY axis's and #'s.