This isn’t the place to discuss “a genuine emergence of classical spacetime geometry from something more fundamental”. I wish you would persuade your colleague and mentor t’Hooft to put a review paper reviewing unorthodox work on the arXiv.org. Until there is a precedent by someone famous, they’ll delete everything submitted that looks crackpot.

…..maybe very theraputic, if someone could finally answer him?

Having said this, I should also say that my own view is that it is not likely that LQG, CDT or anything else now on the table will simply be the right thing. I believe these are all models, necessary steps from which we learn how to do non-trivial calculations in background independent, diffeomorphism invariant quantum field theories. As we gain control over them we are beginning to use the new language and tools gained to address not only quantum gravity but the other big problems such as unification and quantum cosmology. The right theory will solve all of these. And I believe it will do so by featuring a genuine emergence of classical spacetime geometry from something more fundamental.

best,

Moshe

Back to physics, very theraputic…

The comment of continuity was just an intuitive comment, not really necessarily an EFT argument. Basically the spectrum of the string is continuous as a function of the background fields (w/o changing the GSO projection), so string scale tachyon cannot just pop up when you turn on arbitrarily small background fields. In any event, I assure you there are also more complete calculations, that was just an argument why this had to be the case. Incidentally, even for static backgrounds there are non-SUSY classically stable cases, but they are quantum mechanically unstable in the sense that they don’t stay static after including quantum corrections.

As for the last paragraph, I mentioned that in the context of backgrounds which develope singularities, and then we don’t have a criteria for judging which background lift to the full quantum theory. My bet is that weakly curved backgrounds should be fine, but one cannot know for sure yet. (incidentally, is it always true that for time dependent background singularity thm. dictate there generaically exists future or past singulairty?)

best,

Moshe

Thanks very much for your #137. This is helpful, but can I query you on one point, where you say that on “…backgrounds that are almost flat, then just by continuity the only thing one has to worry about is the spectrum of modes that would have been zero modes in flat space. So my statement is that weakly curved solutions of string theory have tachyons if and only if the corresponding GR+matter solution is stable. So string theory at the classical level is as stable or unstable as the corresponding field theory it includes.”

Can you fill in a few details of this argument? It seems to me that given that the cancellation of the tachyon involves a projection to a smaller state space (the GSO projection) and given that the projection implies spacetime supersymmetry which is broken as soon as there is any time dependence, you have to show that you can continue to impose a projection that eliminates a tachyon for any small non-supersymmetric deformation of the background geometry. Has this been done? If not, I don’t think you can use an effective field theory argument that assumes that the tachyon is absent from the deformed theory.

On a related point, you say, “It is certainly not clear that a generic classical solution of any theory, especially containing gravity, should lift to a full solution of the quantum theory.” But for the classical theory to be recovered as the low energy limit, must it not be that every solution to the classical theory that is weakly curved on the Planck scale must lift to a coherent state in the quantum theory?

Thanks, Lee

Will string theorist’s burn in hell?

Some might use religion to distort the “empowerment” we all have? Place it outside of ourselves? While I say, it is quite feasible that such delusions, would have been sought to fool the public, by being anti-stringy?

Is it a plot un-becoming? If one could have a delusion about it’s inception, then why not the reverse of it’s recognition? Claim it to be a positive thing about our comprehension about it’s negative impact?

Have I followed the proper logic?

While in some cases that math is very abtract and models created, how diverse would this reality of math become if it were exposed to the fashionable world call physics and supported?

In game theory you might not have recognized this bargaining process, yet you had two superpowers engaged, and from it attitudes and adoptions. Now, the science has changed. What is this world like, that these two powers have been reduced in the arms race to now confront, the rogue states with weapons manufacture?

The balance although it still exists and might have been in jeopardy with the Ukraine? Some kind of peace has been maintained. Yet, the dynamics and math has indeed changed. The cold war era had ended and with it a fear induced state. Now, what fear has this “new society” to worry about?

Your link to 2005 Nobel laureates for economics (game theory) mentions their theory for winning a nuclear war:

“US citizen Thomas Schelling and Israeli Robert Aumann have won the 2005 Nobel prize in economics for their work in an area known as game theory.

“Professor Schelling has specialised in explaining strategies of international conflict, such as nuclear war. Professor Aumann has developed the theoretical underpinnings of bargaining, co-operation and conflict.

“Professor Schelling, 84, a US citizen … emeritus professor of political economy at Harvard University, where he had taught for 20 years….

“Thomas Schelling told reporters that “they (the Nobel committee) linked us together because he is a producer of game theory and I am a user of game theory.”

“Indeed, both the USA and the former Soviet Union adopted such a strategy - known as mutually assured destruction - during the Cold War, when they developed long-range nuclear weapons but agreed not to develop defensive weapons such as ABMs.”

- http://news.bbc.co.uk/2/hi/business/4326732.stm

This is interesting. They gave the Nobel Peace Prize to a pacifist who campaigned against nuclear weapons for 60 years a while ago, and now they’ve given the economics Nobel Prize for the deterrent use of nuclear weapons! How nice that nuclear physics is both good and bad.

The ATLAS detector uses two large magnet systems to bend charged particles so that their momenta can be measured. This bending is due to the Lorentz force, which is proportional to velocity. Since all particles produced in the LHC’s proton collisions will be traveling at very close to the speed of light, the force on particles of different momenta is equal. (In the theory of relativity, momentum is not proportional to velocity at such speeds.) Thus high-momentum particles will curve very little, while low-momentum particles will curve significantly; the amount of curvature can be quantified and the particle momentum can be determined from this value.

Maybe the psychology needed some “revisionistic ideas” in terms of the layering. As detection processes? UK awareness with physics people and government MP’s?

Socialogical expansionistic processes, from the man on the street, to the man in his country? Reveals a deeper underlying math, that becomes hidden within government agendas and policies? Who knew poltical agendas could have become so compicated at it’s core. While realistic in all the “mazes” of our everyday thinking.

Lessons learnt with John Nash and his bargaining processes exemplifying this underlying recognition? The further exposition in “new” nobel prize winners for game theory?

You see?

You may do OK in Holland, but in Britain A-level physics is declining:

http://news.bbc.co.uk/1/hi/education/3580742.stm

“There are more pupils taking A-level psychology than physics - and if current trends continue, the declining science subject will be overtaken by sociology…. Physics is in decline and other subjects, such as media studies and art, are increasingly popular despite the poor career prospects they offer. It’s a crazy situation,” says Dr Julia King, chief executive of the Institute of Physics.”

I think the high level of abstruse maths which fails to tackle with mechanisms for forces, is not helped by marketing physics using wormhole and Hawking speculations. Hawking sells a lot of books in Britain, but fewer people study physics. I’m not saying I doubt hawking radiation, only that it’s not been found because it’s swamped by the natural background gamma radiation of space. The whole basis of the energy-time version of the uncertainty principle is going to be causal (random interactions between the gauge boson radiation, which consititues the spacetime fabric).

Heuristic explanations of the QFT are required to further the basic understanding of modern physics. For example, Heisenberg’s uncertainty (based on impossible gamma ray microscope thought experiment): pd = h/(2.Pi), where p is uncertainty in momentum and d is uncertainty in distance. The product pd is physically equivalent to Et, where E is uncertainty in energy and t is uncertainty in time. Since, for light speed, d = ct, we obtain: d = hc/(2.Pi.E). This is the formula the experts generally use to relate the range of the force, d, to the energy of the gauge boson, E. Notice that both d and E are really uncertainties in distance and energy, rather than real distance and energy, but the formula works for real distance and energy, because we are dealing with a definite ratio between the two. Hence for 80 GeV mass-energy W and Z intermediate vector bosons, the force range is on the order of 10^-17 m. Since the formula d = hc/(2.Pi.E) therefore works for d and E as realities, we can introduce work energy as E = Fd, which gives us the strong nuclear force law: F = hc/(2.Pi.d^2). This inverse-square law is 137 times Coulomb’s law of electromagnetism.

Surely the heuristic explanation of this 137 anomaly is just the shielding factor by the polarised vacuum?

‘All charges are surrounded by clouds of virtual photons, which spend part of their existence dissociated into fermion-antifermion pairs. The virtual fermions with charges opposite to the bare charge will be, on average, closer to the bare charge than those virtual particles of like sign. Thus, at large distances, we observe a reduced bare charge due to this screening effect.’ – I. Levine, D. Koltick, et al., Physical Review Letters, v.78, 1997, no.3, p.424.

My grandson who is nine, wants to a experiment with magnets. I thought of Einstein’s youth and the magic of the compass. Would it have a similar impact on him? I can only hope

So, any ideas on what we can plant into society, that such a child will open new doors to a brighter future, for all of them. Make them wonder more. A new view that would hold their interest?

‘The special theory of relativity … does not extend to non-uniform motion … The laws of physics must be of such a nature that they apply to systems of reference in any kind of motion. Along this road we arrive at an extension of the postulate of relativity….’ – Albert Einstein, ‘The Foundation of the General Theory of Relativity’, Annalen der Physik, v49, 1916.

‘The Michelson-Morley experiment has thus failed to detect our motion through the aether, because the effect looked for – the delay of one of the light waves – is exactly compensated by an automatic contraction of the matter forming the apparatus…. The great stumbing-block for a philosophy which denies absolute space is the experimental detection of absolute rotation.’ – A.S. Eddington, Space Time and Gravitation, Cambridge, 1921, pp. 20, 152.

So the contraction of the Michelson-Morley instrument made it fail to detect absolute motion. This is why special relativity needs replacement with a causal general relativity:

‘According to the general theory of relativity space without ether is unthinkable.’ – Albert Einstein, Leyden university lecture ‘Ether and Relativity’, 1920. (A. Einstein, Sidelights on Relativity, Dover, 1952, p. 23.)

‘… with the new theory of electrodynamics [vacuum filled with virtual particles] we are rather forced to have an aether.’ – P.A.M. Dirac, ‘Is There an Aether?,’ Nature, v168, 1951, p906. (If you have a kid playing with magnets, how do you explain the pull and push forces felt through space? As ‘magic’?)

‘Children lose interest … because a natural interest in the world around them has been replaced by an unnatural acceptance of the soundness of certain views, the correctness of particular opinions and the validity of specific claims.’ – Dr David Lewis, You can teach your child intelligence, Book Club Associates, London, 1982, p. 258.

Of course, string theory is especially simple and trivial (when compared to advanced stuff) and does not contain the adequate mathematical structure for being considered a true theory of everything. It is easily proven that from theories and models already available on literature (and others in press) one can obtain string theory framework on well-defined limits. Therefore, it is not so surprising for us –some string theorists are really astonished– that from early ideas of chemist Ilya Prigogine one can generalize non-critical string theory beyond usual limited trivial framework of wavefunctions and scattering.

Still more interesting is when one revises all of that supposed ‘advanced stuff’ and one finds just trivial math, and even formulas incorrectly copied from previous work of others. Nanopoulos’ work “as time goes by…” [arXiv:hep-th/9406016 v1 3 Jun 94] is a fascinating example of how science may not ‘goes by…’!!

For some basic ideas on why string theory has failed as a true theory of everything and why, even in his most advanced versions, it looks very trivial from rival theories, the reader can see “String theory is not a TOE” on sci.physics.strings.

Today almost all of string theory research looks in the wrong way: symmetry groups, AdS, dualities, 10-11D spacetimes, non-commutative geometry, quantum states (even using TFD-Dpbrane), evolutors, and a large etcetera.

Moreover, string theorists just are ignoring recent experimental data and advances in other fields. There are experiments proving that QED is not completely correct but other rival theories can explain them (see Discrepancies on QED )

There are serious mathematical flaws in all the formalism of string theory (for example still nobody proven to me the absence of divergences). String theorists claim quantization of gravity, but far from rather trivial ideas (of course, 30 years ago the perspective was very promising) about a two-spin model in a flat background and similar ones, there is not real understanding of gravity on the string-brane side. In fact, it is highly probable –even if this sound ‘crank’– that GR cannot be considered the final approach to classical gravity (of course here other alternatives as LQG are not doing it better).

Discrepancies in cosmological regimes, serious mathematical difficulties, and the unsolved character of the main fundamental problems of GR (e.g. problem of energy, problem of reference frames, the speed of gravity problem, the lacking of a consistent Newtonian limit!, etc.) would reconsider the status of the foundation of GR even before our attempt to quantize it.

In fact, some other authors have obtained a first generalized gravitational theory that explains experimental data, and corrects GR errors. Interestingly, that new theory of gravity has been already quantized from basic principles in a non-perturbative manner without the typical problems of ‘absence of time’, wrong causality (in perturbative regimes as string) and similar ones.

Note: Usual ‘Newtonian limits’ on literature are computed via incorrect limits (usual textbook ‘derivation’) incorrect math (wrong functional dependence for potentials in NC theory), via unphysical boundaries (Ehlërs approach), via appealing to NEW postulates does NOT derived from GR (Christian approach), etc.

Note: it can be proven that the problem of aberration in experimental gravity is NOT solved via Carlip article [S. Carlip, Phys. Lett. A 267 (2000) 81-87.] or similar attempts.

On String Math
As a well-known part of string theory propaganda, it is claimed that string theory is providing new revolutionary ways on math. Well, this is not true. It is true that string theory use entire branches of math that particle physics does not use, but string theory has not invented or developed those branches. There exist some collaboration between mathematicians and string theorists, but the real impact of PURE string theory on math is insignificant. The current view of two Field Medals were awarded to research on string theory is so popular as incorrect.

On String Marketing
How many people still believe that main idea under string theory is that all ‘matter’ is composed of small one-dimensional objects and spacetime is 10D? When you explain to people that string theory is already NOT a theory of strings, they look you with a face… Still more interesting is that after of decades of explaining to us why the point-like objects of particle physics could not be correct, since, at small scales, pieces of nature “would be” extended objects, now some M-theoreticians claim that the fundamental item of nature are, exactly, point-like objects called D0-branes. Of course, D0-branes are not the ‘old’ particles of the Standard Model, but definitively are not the popular one-dimensional strings.

I personally find very amazing the history of the field with almost all of previous -premature- claims proven to be completely wrong. It is sensible continue with that fascinating record of failure?

Other example is that of ‘predictions’. In theory, string theory is a framework that predicts everything using a single parameter. Yes, that was the belief… but today we know that string theory can predict exactly nothing even if one use several dozens of hundred of parameters…

Would not people who are paying string theory research know those important details?

On Einstein achievements
“the one intelligently designed” said

Eienstien wrote GR based only on his theoretical insights and demanding some general properties for a theory of gravity ( relativistic invariance, equivalance principle ect) and then looking for internal consistencies.

In fact, Einstein failed to obtain a consistent theory until he read a previous Hilbert paper where Hilbert obtained the correct field equations of GR. Then Einstein submitted the famous paper of day 25 without citing Hilbert. Still more interesting is that in that paper Einstein simply postulated the correct equations of GR. (see what is history of relativity theory?).

Juan R.

Center for CANONICAL |SCIENCE)

It is completly possible that the LHC discovers that mathematics no longer governs the universe below a certain length scale. Personally, I wouldn’t bet on it but it’s possible.

Yes.

And it’s possible that, tomorrow, we will discover a room-temperture superconductor where the charge-carriers are angels. It’s “arrogant” to say that’s impossible.

C’mon. There will always be experimental surprises. And there will be theoretical surprises, too: loopholes discovered in previously airtight-sounding theorems (string theory itself is such a loophole).

Under such circumstances, I’m perfectly prepared to eat my words.

But the mere possibility of such surprises should not reduce us to labelling every as-yet-not-experimentally-verified statement to the status of mere “opinion” or rank “speculation.”

You wouldn’t do that in your field; please don’t expect me to do that in mine.

If you disagree with the arguments in the aforementioned blog post, or if you disagree that they imply my remark above, then let’s have-at-it. But I don’t think you can just dismiss the arguments as mere “arrogance”.

If you reread my statement you’ll see that it is not the content of your statement I took issue with, it is the tone. And to tell the truth, I have no desire to have-at-it with anyone about issues that don’t effect my world, but never-the-less I’ll waste my time and respond.

I may not know everything, but I do know some things. As a condensed matter theorist (formally trained in the art of wild speculation) I understand the process clearly. We publish some predictions, experimentalists verify said predictions. Some times the most far fetched ideas are correct, sometimes the most elegant and attractive ideas are wrong. The point is that physics is harder than most of us are smart, and if we aren’t guided by experiment it could be healthy to inject a dose of humility into our speculations.

It is completly possible that the LHC discovers that mathematics no longer governs the universe below a certain length scale. Personally, I wouldn’t bet on it but it’s possible.

Under these circumstances, it seems to me, that statements like “you won’t get very far with me saying…yadda, yadda, yadda”, should be replaced with statements like “Well, I believe blah, blah, blah and most professionals would agree that yadda, yadda, yadda is unlikely. But, we have to wait for experiment or, at a minimum, some accurate postdictions to be sure”.