Essay Abstract

The ultimate limit of physics is not a theoretical limit, but rather an experimental one; without testable results (at least in principle), any purported theory could not be said to be physical, or even an application of the scientific method. Using a few basic tools from modern physics, this essay is an attempt to deduce those ultimate experimental limits.

This analysis ascribes a central importance to the very successful variational principles (VPs) used in both general relativity and quantum theory. Applying such VPs in some measureable 4D region of spacetime requires one to constrain partial-information boundary conditions on the 3D (hypersurface) boundary of that 4D region. Given the key premise that the constrained, mathematical boundary conditions in VPs directly correspond to values constrained by actual external measurements, one can build up a probabilistic block-universe framework that seems capable of encompassing future developments towards a general theory of measurement and quantum gravity. A general analysis of the ultimate experiments explainable by such a theory yields a reasonable estimation of the limits of physics.

Author Bio

Ken Wharton is an associate professor in the Department of Physics and Astronomy at San Jose State University. His research is in quantum foundations, with a particular interest in approaches outside the standard quantum formalism that permit a straightforward extension into the framework described by general relativity.

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I'm rooting for you, Ken. Theory predicts what it is told to predict. Alas, not here. Look at the competition's content and how it is regarded by FQXi keepers - don't ever look! "Charged photons - an educated guess" (are supernovae dedicated to irony?) is FQXi rated 2.7. If photons are charged, what then of vacuum photon-photon scattering? Phys. Rev. 46 1087 (1934) and then Phy. Rev. Lett. 79 1626 (1997) are definitively falsifying. "Pursuing the Limits of Failed Symmetry," consistent with theory and with a punctilious and facile experimental program to validate or falsify its conjecture, rated a 1.4. Don't look!

Draw a triangle on a globe of the Earth to make Euclid cry. String theory and SUSY are viable precisely because they cannot be tested. They are stable guild employment. That they embody testable founding postulates is heresy of the blackest sort. Somebody should look.

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Hey Ken, nice essay! I have mixed feelings about some of your points, though. The first is a minor point - that inflation is "unproven" physics. It had been my impression that inflation is on pretty solid ground as a model (mind you, my opinion is colored by my view of what physics is - so you might want to read my essay). The second is this assertion that we can ignore the theoretical when probing the limits of physics. The reason I think we can't is because the theoretical side often drives the experimental side (and, of course, it works the other way around). Both are indispensable. What I mean is that it is sometimes radical theoretical concepts that give us the ideas for our experiments. Pushing theory to the boundary should act as a check and balance against pushing experiment to the boundary. They're inextricably linked. Also, I wonder about the range of applicability of VPs. It seems to me that I could envision problems in which you simply do not have enough information.

Nevertheless, I did like your take on conditional probabilities and your use of joint probability distributions. I have always thought there was some deeper connection between conditional probabilities, epistemic states, and reference frames, but haven't gotten beyond the "pondering" stage.

Good luck!

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Hi Ken,

Glad to see you entered the contest. I enjoy reading your essays whether I agree with you or not because you write so well. In this case, there is one point I'm wondering about.

Perhaps I'm missing something, but it seems your view of measurement on the hypersurfaces enclosing 4-volumes assumes a separable spacetime structure, what Healey calls "constitutively local." If I'm right, how do you see your thesis being modified by constitutive non-locality? If you're not sure what I mean by this, see Figure 8 and comments pertaining thereto in our arXiv paper.

Mark

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A copy of this message is being left in each thread of the essay contest forum.

Submitters: Tired of constantly checking the FQXI site to see how your paper's doing in the rankings? I've written a simple program that periodically checks the FQXI site and sends you an email if the status of your paper has changed in any way. Here is a sample email:

The following changes were detected in the status of your paper:

* Number of posts in discussion forum went from 0 to 20.

* Community rating went from 0 to 3.4.

* Community vote count went from 0 to 10.

* Public rating went from 0 to 4.3.

* Public vote count went from 0 to 6.

* Community ranking went from being in 0th place to being tied for 16th out of 112.

* Public ranking went from being in 0th place to being tied for 19th out of 112.

You just run the program once, in a command prompt window, and then minimize that window and let it do its thing in the background.

If you're interested in a copy (with source for those who care) drop me a note at ramblinplan@yahoo.com.

Thanks,

Owen Cunningham

P.S. This program requires Windows and the .NET Framework. It has been tested only on Windows XP Service Pack 3 running .NET Framework 3.5, but has a good chance of working with earlier versions.

Ken

A first class essay about real physics.

I have one disagreement with your views. Although you recognise it is non physical, you still place heavy reliance on the 4D block universe formalism. Unfortunately you allow it to prescribe your physical conclusions too much. In due course you are confronted by one of these unfortunate consequences - that QM can't handle the absolutely necessary and unavoidable measurements on Time-like spaces of the formalism.

I agree completely that experiment comes first; but as your essay shows we must have some formalism (an epistemology) in which we express our measured results (an ontology). You have no choice but to use the 4D one. Suppose as I discuss in my essay that it is the formalism, including the 4D continuum, that is at fault because it is inadequate. Then even though you are proposing correct physical principles, they cannot express our reality correctly because they are expressed through that faulty formalism.

Until we have the correct formalism your correct physical principles will be shrouded by unscientific mysteries that, as Feynman said "No one understands". A formalism that replaces the Block View with an instantaneous Now is what we need. Such a formalism would of course correspond precisely with everyones experience under all circumstances. Philosophers call it Naive Realism !

PS In fact a major point of your essay is that actual physical measurements are between two different "NOWS". Hence all that hyper-surface stuff. Implicitly you are making my point.

12 days later

Hi Ken:

I thought I submitted a comment earlier to the effect that it is nice to see a real physics paper by a real physicist. I still hold to that and think you have done fine work in this paper. I agree with Uncle Al that the ratings are arbitrary and capricious and there's definitely an "I'll vote for you and you vote for me" club out there and one doesn't need quantum game theory to explain it :-) I think you hit the nail on the head about unverifiable theory and this is the central problem in string theory. I wonder what you think of Julian Barbour's treatment of the dynamics of pure shape in GR (http://arxiv.org/PS_cache/gr-qc/pdf/0309/0309089v1.pdf) I'm not going to do the annoying thing that I see most other people do and tell you where I agree and disagree with your paper and throw a reference to my work at you, but I'd also be quite interested to know whether you think Hawking's assertion that we will eventually discover hidden non-local variables is relevant to the problems you raise in your paper and whether you see this in the future of gr-qc.

Cheers,

Phil

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Thanks, everyone, for the comments -- here's a quick stab at all the questions in the above posts.

Ian: Concerning inflation, it's certainly widely accepted, but that only means that the *problems* with it have been widely rationalized as acceptable, not that there aren't any serious problems. The biggest point in inflation's favor was a "prediction" of scale invariance of the CMB (although this prediction actually arose before inflation ever existed). But this central point in its favor has now been dealt (i.m.o.) a crippling blow by research pointing out that such scale invariance should occur even without inflation; see http://arxiv.org/abs/gr-qc/0205058 .

Your other main point, that experiment needs theory to tell it where to look, is a very good one, and I certainly did ignore that in my essay, if only to stress that *some* theories can leave experiment so far behind that they aren't really physics anymore. But I also obliquely made your point, in that my (largely theoretical) discussion *did* imply where experimentalists should focus their efforts (on measuring the time between consecutive measurements, and on time-like hypersurfaces). Still, when one is talking about ultimate (i.e. all possible) measurements, having theory tell you "where to look" is largely irrelevant: the ultimate experiment will look *everywhere*. (Of course, it's easy to talk about measuring all measureable quantities -- the hard part is actually doing it!)

Finally, your comment about variational principles not having enough information is exactly my point. However much information you need to solve initial-boundary-problems, you only need half as much information on the initial portion of a variational problem. Of course, it's easy to envision problems where neither case has enough information to solve the problem, but there's no case where you have enough info to solve (and verify the solution to) a non-variational problem, but still not enough info to solve the corresponding variational problem.

Mark: Certainly everything one is measuring is constitutively local, in my view -- but (this the the key point) the measurement itself is non-local, in that it spans a finite region of both space and time. All my so-called "non-local" effects come from this non-local constraint on local "constituents". I have a pathological aversion to the concept of constituents that somehow obey non-local equations -- I can't see how they could possibly work in a GR-compatible framework -- so I haven't given them much thought.

Terry: You're absolutely correct that if my premise of a 4D block universe is incorrect, then my conclusions will be incorrect. The conflicts between QM and the block universe are discussed in Ref. [1], and I think that choosing the block universe formalism over QM's formalism is the right path to resolve the "mysteries" that you mention. As for whether our physics has erred by not taking our experience of "now" into account... I have the exact opposite view. We've erred by taking it into account more than we should have! Despite the fact that "now" doesn't show up in our equations, we insist on squashing our 4D universe into 3D states that purportedly describe everything there is to describe. The reason QM and QFT are built this way is because our brains instinctively think in terms of "nows". In my opinion, we need to fight this human instinct to make progress -- it's the way that our brains think about time and causality that create all these "mysteries" in the first place.

Philip: As much as a revolutionary as Barbour is, I think he's building on a faulty foundation -- Einstein, I think, was one of the few people to see where the proper foundation should have been built, but even he couldn't quite give up on the idea of solving everything with initial boundary conditions. As for "non-local hidden variables", you might read my response to Mark above. It all comes down to what is meant by "non-local", but as I see it, the ultimate physics theory won't contain any variables any more non-local than, say, the E and B fields in Maxwell's equations. Few people would say that these were non-local... But if you impose a future boundary condition on the equations, then the E's and B's at any particular point in spacetime "Q" now depend on that future boundary condition. And the fields at another point in spacetime, "R", depend on the same future condition. And now there will be interesting correlations between the E and B fields at Q and R, seeming "non-local" correlations that can't be explained by virtue of what has already happened. Does that mean that the E and B fields in Maxwell's equations can be transformed into "non-local hidden variables" simply by putting future boundary conditions on a system? It depends on what you mean by that phrase. Maybe it's just safer to say that I think that all physical variables will solve local field equations, and leave it at that.

Thanks again, everyone, for all the kind comments.

5 days later
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i note that you are interested in the foundations of Quantum mechanics. I got laid when one finds that both particle and wave nature become synonimous with all physical processes pertaining to the microworld of nuclons, nuclei, atoms and molecules.the classical physics thus gets associated with the macro-world where the particle and wave distinctions get separated. However, quantum mechnanics is valid throughout, as all its results tend to classical ones as one turns Planck's constant h to zero.

Now the problem arises as to the holiness of constant h to be either zero or its full value as ascertained through experoments pn processes that follow quayum mechanics. Is there no in between region where h is neither 0 nor has its designated magnitude. Does physics is bound by two distinct regions with no overalpping in beteen region? Some recent cosmological measurements though isolated, suggest that the value of c, the velocity of light was higher for objects way behind 12 billions. Also, similsr results were obtained for the ratio e/m for light spectra of distant galaxies/stars. If that is so, we can not be sure that the value of h has remained constant since the birth of the universe. In fact, on the basis of different values for c and e/m, i expect the value of h to be smaller near the burth of the universe.

In such a scenario, we expect Physics to be different for the early universe period than what we have evolved over the past few hundred years. The ssay by Tejinder Singh on this forum has proposed an inbetween region called mesomorphic that is in between the classical and quantum extremes. Investigations require samples that have atomic/molecular mass closer to Planck mass. Now such objects may well be prepared as nanostructured heavy 'atoms' of gold. Experimental investigations with such samples will not follow either quantum or classical physics. In fact i believe that many of the mysteries like dark matter/energy, black holes may wellbe amiable to a better understanding of such an intermediate region.Any takers or objectors to such a scenario in Physics!!

Hi Ken:

A couple of quick points, and since you know I like your essay, I hope we can discuss this in a non-adversarial fashion (as Terry Padden and I have been doing) rather than the "you've got it all wrong, see my essay for details - btw thanks for the careful reading our essay, something that none of us with detailed professional arguments have gotten enough of so far. I was wondering with respect to your answer about my point on Maxwell's equations, and to some extent it is probably more your introducing them in a global fashion, but in either case, I have to ask, do you mean Maxwell's equations as he originally formulated them in quaternionic fashion, or the revised equationsd formulated by Oliver Heaviside that everyone calls "Maxwell's Equations". Also, have you seen Peter Jacks' 2001 solution to differentiating left and right non-commutation in quaternionic equations (http://arxiv.org/PS_cache/math-ph/pdf/0307/0307038v1.pdf) which, I think is the proper way to think about the classical formulation of Maxwell's equations. We're working on a treatment of this in terms of a "slight deformation" of quantum mechanics in order to include higher order terms of Maxwell's equations (which were dismissed by Einstein as having insignificant values, which clearly we disagree with, and even Rosen of EPR also disagreed with although we think we may disagree more comprehensively - our paper will show up in the ArXiv eventually on its way to publication). Anyway, without banging on our own idiosyncratic points (which you know is one of my principal objections to much of the discourse in this contest). I think the part of Julian Barbour's work to which I might have an objection (and this comes in some part from his "global" worldview because I am a very big fan of his technical work, as you know from our comments on his derivation of York scaling and the Lichnerowicz-York equation) is the part where he and Peter Lynds disagree, and that is his reliance on static instants in order to build his cosmology, which I regard as "block universe" model. I'm not really sure he holds so closely to Einstein, and in fact, I am quite sure that his studies on the dynamics of pure shape ( arXiv:gr-qc/0309089, arXiv:gr-qc/0211022, arXiv:gr-qc/0211021) and his line of reasoning on "Relativity Without Relativity" ( arXiv:gr-qc/0012089 and arXiv:gr-qc/0201092) are quite opposed to an Einsteinian point of view. I think the business of starting with Einstein was an artifact of last year's competition and we may be guilty, in an 8 page paper of overly emphasizing this aspect of his work.

Cheers,

Phil

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