A Universe Programmed with Strings of Qubits by Philip Gibbs

The reply above is mine. Sorry about not entering my name.

Ervin

I know the feeling. It could be the case that physics above some scale is completely different from anything we have seen so far. Without much hope of experimental input we would never figure it out. We would have no more hope of understanding the laws of physics than a cat has of understanding quantum mechanics.

I am more optimistic than that and I will tell you why. When we try to bring together quantum mechanics and gravity we find that black holes must have entropy and temperature that extends the laws of thermodynamics in an unexpected and surprising way. To understand how this can work we need to invoke a holographic principle that nobody would have anticipated any other way. When we look for a perturbative theory of quantum gravity we find that we can do it with a theory of strings which turns out to be something we can use to solve deep problems in pure mathematics. Then we find that in this string theory the holographic principle applies just as it needed to for consistency.

If physics beyond some scale is something else then the existence of all these remarkable theories is just a crazy coincidence that has led us all astray. I think there is too big a set of coincidences for this to be likely. In the past when the maths has turned out to work it has later been verified by experiment. The Dirac equation which predicted antimatter is the canonical example, but Maxwell's equations and relativity were similar. With quantum gravity we have pushed out further into unknown territory with no experimental feedback, but the network of mathematical theories that hang together unexpectedly is also bigger and more impressive. I think this is because it is right and the assumptions that have been made were the correct ones. It is still incomplete but progress is still being made. I don't know how long it will take, but I think the signs are that it is something we have the capacity to comprehend.

I think that results from the LHC are likely to help us understand a lot more. I'm not sure which anomalous observations you are referring to but it is early days. I hope the gap between these energies and the Planck scale can be bridged in some meaningful way with a combination of theory and experiment but it is impossible to know how far there is to go.

Nice job! I especially appreciate your faith in the ability of M theory to produce a complete algebraic theory. I agree that continuous function physics is so ingrained in our consciousness that it's often hard to escape.

Tom

Phil,

You say,

"In the past when the maths has turned out to work it has later been verified by experiment"

There are many counterexamples where reality either already fails or may fail to follow appealing mathematical frameworks: chirally symmetric field theories, SU(5) GUT, Deformed Special Relativity, preons, large extra dimensions, Fermi liquid behavior in strongly correlated compounds, spin-statistics connection in fractional Quantum Hall effect, Navier-Stokes equations of fully developed turbulence and so on.

Is there comprehensive evidence that holography works as advertised in strongly coupled field theories? Is there convincing observational evidence that black holes and exotic thermodynamics are able to fully and successfully account for physics of the Terascale sector?

I am not pessimistic when I pose these questions. I want to caution about extrapolations based on beautiful mathematical structures that may turn out to be wishful thinking after all.

.. Still fresh from the old cyclotron...

Philip,

I think the highest and most fundamental symmetry is from the existence/non-existence duality. From this binary symmetry, I can see the Weizsaker approach exploding into a whole universe. Assuming we start with nothing, a whole universe may start to exist from this one cubit. But, as explained in my last essay, only an evolving time can exist at that "moment" and forever after without failing the rule of non-contradiction.

p.s. for other essay writers: don't forget page numbering as this is important for reference in discussions..)

Thanks,

Marcel,

" ... and reverse engineer the program that codes our universe."

A couple of questions:

(1.) What's the basis for assuming that the computation analogy is valid in this context? Does the fact that we think in terms of "programming" mandatorily mean the Universe does?

(2.) NP-Completeness. This is an issue for quantum computation just as much as it is for classical. Could the proposed reverse engineering even be conceivable unless P=NP? Does it?

Phil, if you just shrug your shoulders about the existence or non existence of SUSY partners, you are not doing physics. You have to decide.

As I've said on vixra log I am quite optimistic about SUSY to be found at the LHC in some form, but it is far from certain. It would not directly affect any work I have done if it was not there.

nikman, there is certainly not anything mandatory about the proposal that the world works like a computer. It is just a hypothesis that we can follow in our pursuit of better understanding. A statement like "the universe is a quantum computer" is currently just a motivational buzzphrase. It does not mean a great deal until we can find a concrete mathematical theory for which it is a reasonable interpretation. It may lead to the development of such a theory.

The justification for considering it is certainly not that we think in such terms. Usually that is not a good guide. The justification is that the mathematics of information and especially quantum information comes up in string theory.

It is not obvious whether or not an answer to the problem P=NP would have any implication for physics. Perhaps if we had a better idea of how the computer "analogy" is realised it would be possible to say more about it.

I like it!

So are you doing an essay this time round?

Oh yeah I should have put page numbers, but you can see them in acrobat reader.

I don't find any of the other examples you give as convincing. Obviously not everyone is persuaded by these mathematical arguments, we don't all follow the same ideas.

I don't expect any effect of black holes or holography to show up at currently accessible energy scales.

Dear Phil,

Your essay is interesting, and your comments even more so. You clearly state that the paper is speculative, and your comments are very open minded.

You state above that "If physics beyond some scale is something else then the existence of all these remarkable theories is just a crazy coincidence that has led us all astray. I think there is too big a set of coincidences for this to be likely."

In my paper I remark that "potentials derive from 'point particles' and from the fact that scattering data fixes the strength and range of the nucleon potential, but not its shape. As a result:

The Lagrangian formulation provides a convenient technique for inventing new types of fields and investigating their properties.

The mathematical invention of fields offers no guarantee the fields physically exist. But it does allow the invention of Higgs, axions, dilatons, inflatons, anyons, instantons, WIMPs , sphalerons, gluons, and SUSY particles. None of these have ever been seen.

Because academic physics employs this Lagrangian approach to invent new 'fields', it is not really surprising that "all these remarkable theories" end up looking the same. It's less coincidence than a foregone conclusion. And the common characteristic seems to be that all address a relatively minute problem and ignore most of the rest of the universe. For a different approach that addresses current problems of physics I invite you read my essay. In particular, I invite your attention to a very specific set of problems I list that seem to offer a 'testing ground' for any theory of particle physics.

I also commented that a Phys Rev Lett paper I received yesterday implies that the C-field is responsible for recent measurements that show a difference from general relativity predictions. By submitting early, I missed the opportunity to incorporate this info in my essay, but it is relevant.

Thanks for your fascinating comments here.

Edwin Eugene Klingman

Phil,

With all due respect, I am confused by your arguments. Your reply reads:

"I don't find any of the other examples you give as convincing. Obviously not everyone is persuaded by these mathematical arguments, we don't all follow the same ideas."

Are you implying that beauty and logical completeness of a mathematical theory ought to be enough to secure validity of that theory and replace experimental falsification?

"I don't expect any effect of black holes or holography to show up at currently accessible energy scales."

But if this is the case and holography is out of reach, how can one be convinced that AdS/CFT makes contact to reality?

We might wonder whether gravity is at all completely quantized at all. I think that gravitation is actually an emergent effect. More to the point the near horizon condition of an AdS_4 decomposes into AdS_2xS^2. The AdS_2 is the geometry for the sine-Gordon equation, or soliton wave, which is S-dual to a fermionic theory. So I suspect that spacetime is largely a classical field, with quantization at the tree level or O(ħ). Of course Feynman pointed out that general relativity at this level is formally the same as the classical theory! The quantum mechanics behind gravity exists on an other "substratum."

Cheers LC

Philip,

I have not decided yet. I have a problem with the question. It shows a philosophically challenged attitude. In my essay about physics and metaphysics I explain the difference and importance of a fundamental approach based on logic

applied to ontology. I take nothing away from physics, but physics must recognize its limits and they are real. I might come with further arguments but with nobody

at the receiving end, I feel it is somehow pointless.

Marcel,

To the extent that our many confusions and impasses devolve from limitations of the human mind, if P=NP the implications for physics would be beyond anyone's imagination. Mathematical creativity could in theory be automated. Almost all questions that might be asked could be answered. We'd even have a step-by-step quantified physical model for protein folding (surely next to nothing in the great cosmological scheme of things) instead of probabilistic diagrams per statistical physics. The Theory of Everything might be within our reach. What's not to reverse engineer? As Scott Aaronson puts it: "We would be almost like gods."

Or as Frank Wilczek replied when asked what yes-or-no question he'd ask a super-intelligent alien if he were allowed only one: "P versus NP. That basically contains all the other questions, doesn't it?"

If P doesn't equal NP a lot of bets could be off. This is independent of the issue of whether or not the universe computes in any meaningful sense. Is computation itself -- classical, quantum -- robust enough to compress and make comprehensible the fundamental information we hope is out there?

"...If it is because mathematical logic or experiment confirms that they are right, then that's fine. If it is just because we have grown used to the formalism then we need to question if it is the right way to go forward..."

True, Philip, but the trouble is that we have become so clever at mathematics it is possible to frame experimental results in many different ways that seem to point in contrary directions. That is when the second part of your sentence kicks in..the formalism we have been educated in blinds us to other views that may be equally valid but not as 'fashionable'. I am far from being an expert but wonder if theories get shot down for contradicting some minor tenet of a rival theory, and not for contradicting its own premises or experimental results?

Sorry this is off-subject, but it is unfortunate the that name of the black-hole related "holographic principle" has sort of upstaged another possible holographic principle. Holograms have a unique property that if you cut a small portion of the film it will encapsulate the larger picture but at lower resolution. As in fractals, and sort of like how nature seems to work- the universe in a grain of sand sort of thing!

Ervin, I don't think it "ought" to come out that way, but I think it might. Do you think it couldn't?

The AdS/CFT correspondence only works for supersymmetric theory. For non-supersymmetric QCD it may be an approximation but I doubt it would lead to anything other than qualitative results.

Verifying the holographic principle by direct observation may never be possible, just as we may never be able to detect Hawking radiation from a black hole. These things might be forever theories which are necessary to accept for consistency. I am not saying this has to be the case. There are other ways things could pan out.

"I am far from being an expert but wonder if theories get shot down for contradicting some minor tenet of a rival theory, and not for contradicting its own premises or experimental results?"

Yes, this happens. New ideas are sometimes hard to accept because they contradict an old dogma. My series of blog posts about "crackpots" who were right provided a number of historical examples. However, these cases are rare, usually the expert consensus is right, but not always.