Monday, November 05, 2007

New Hope in Physics

During my recent religious experiences I realized that, ironically, my views were for the first time in years consistent with what seems to pass for mainstream scientific opinion, at least in physics. For example, it now made sense that there was a Big Bang -- after all the Biblical view is that God created the universe. There are of course numerous religious and otherwise mystical people taking advantage of the philosophical state of physics ever since the early 20th century.

Objectivists have always taken a quite different line. Ayn Rand in 1934 wrote in her philosophic journal:
I have to study: philosophy, higher mathematics, physics, psychology.
As to physics--learn why mind and reason are so decried as impotent when coping with the universe. Isn't there some huge mistake there?

May 15, 1934, Journals of Ayn Rand, Ed. David Harriman, Dutton, p.72
Ayn Rand is of course referring to Quantum Mechanics and the bizarre interpretations that people to this very day continue to ascribe to it. As a result, even great physicists such as Richard Feynman are quoted saying:
What I am going to tell you about is what we teach our physics students in the third or fourth year of graduate school... It is my task to convince you not to turn away because you don't understand it. You see my physics students don't understand it. ... That is because I don't understand it. Nobody does.
(Feynman, Richard P. Nobel Lecture, 1966, 1918-1988, QED, The Strange Theory of Light and Matter)
Of course, the main problem for Objectivists with physics are the claims that seem to go against the principle of causality. The law, as Ayn Rand grasped it, was stated by the character John Galt in Atlas Shrugged:
The law of causality is the law of identity applied to action. All actions are caused by entities. The nature of an action is caused and determined by the nature of the entities that act; a thing cannot act in contradiction to its nature …
Perhaps even more important when it comes to quantum mechanics is the following elaboration that Leonard Peikoff gave in his essay The Analytic-Synthetic Dichotomy which is contained in Ayn Rand's Introduction to Objectivist Epistemology:
Since things are what they are, since everything that exists possesses a specific identity, nothing in reality can occur causelessly or by chance.
Physicists such as Werner Heisenberg with his Uncertain Principle certainly seem to beg to differ as the following excerpt from an exhibit at the American Institute of Physics shows:
Heisenberg realized that the uncertainty relations had profound implications. First, if we accept Heisenberg's argument that every concept has a meaning only in terms of the experiments used to measure it, we must agree that things that cannot be measured really have no meaning in physics. Thus, for instance, the path of a particle has no meaning beyond the precision with which it is observed. But a basic assumption of physics since Newton has been that a "real world" exists independently of us, regardless of whether or not we observe it. (This assumption did not go unchallenged, however, by some philsophers.) Heisenberg now argued that such concepts as orbits of electrons do not exist in nature unless and until we observe them.

There were also far-reaching implications for the concept of causality and the determinacy of past and future events. These are discussed on the page about the origins of uncertainty. Because the uncertainty relations are more than just mathematical relations, but have profound scientific and philosophical implications, physicists sometimes speak of the "uncertainty principle."

Dr. Peikoff has claimed for some decades that the "uncertainty principle" mentioned above, if by that is meant a denial of causality, cannot be true. Philosophy here has "veto power" over science. Science cannot deny its hierarchical roots -- all science depends on the law of causality. This would no different than any claim that Higher Mathematics (such as calculus for example) disproves basic arithmetic. It simply couldn't make any sense. Helpful in this regard was a paper authored apparently in the 1990s by Objectivist Physicist Dr. Hans Schantz, which unfortunately is no longer available online (though it is available in the web archives), that showed that it was the acceptance of modern philosophy by the founders of quantum mechanics such as Heisenberg and Bohr that led to their denial of causality and not any experiments.

But it's one thing to deny that physics implies a lack of causality and quite another to propose a new physical interpretation that explains all the experiments in a causal way. Many physicists have tried and failed to do this, beginning with Nobel Prize Winner Louis de Broglie and David Bohm who formulated an alternative causal interpretation of the physics:

In standard QM every particle can be observed either as a particle or as a wave. The wave is not physical, like water or sound waves, but a wave of probability in an abstract space. When a photon goes through one slit in a barrier, to register on a detection screen, it is a particle. When two slits are open, the photon behaves like a wave and it is impossible to tell which slit it goes through without destroying the wave. If many photons are sent through a barrier with two openings, each registers on the screen as a particle, but they display an interference pattern that could only be produced by a wave going through both slits. The photon is a mysterious thing. It is neither wave nor particle, but something that can act like one or the other depending on the measuring apparatus.

In Bohm's revolutionary theory, as refined by his associate Basil Hiley, particles are as real as golf balls. At all times they have precise, unfuzzy properties such as position and momentum, and precise paths through spacetime. The particles are never waves. Associated with each particle is an invisible, undetectable wave in a field which Bohm called the "quantum potential." Its pilot waves are real waves, not probability waves. They guide the particle's motion in a manner somewhat like the way a rivers wave guides the movement of a floating leaf, or, in a better analogy, the way radar information guides a ship. This quantum field, like the fields of gravity and electromagnetism, permeates all of spacetime, but unlike those fields its intensity doesn't diminish with distance. Also unlike other fields, it exerts no force on particles. Essentially it is a wave of undecaying information. [Skeptical Inquirer 5/1/2000 Martin Gardner]

The Broglie-Bohm approach seems promising but involves another problem that many also consider philosophically problematic -- the idea of non-locality. The way this issue is introduced usually involves a description of the Einstein-Podolsky-Rosen (EPR) thought experiment that these three scientists proposed in order to point to the necessity for "hidden variables" to underlie the surface randomness of quantum mechanics:

The EPR paradox has several forms, but the easiest to understand was proposed by the late American physicist David Jacob Bohm (1917-1991). It involves a mysterious property of particles called spin. Spin is roughly similar to the motion of a top because it has angular momentum that always takes one of two forms variously called left or right, plus or minus, up or down. Imagine a quantum reaction that creates two identical particles A and B which go off in opposite directions. In standard QM each particle has its left and right spins "superposed." When particle A is measured for spin, its "wave function" (a formula specifying the probabilities that certain values will be found when a particle is measured for a given property) is said to "collapse" (vanish). The particle at once acquires either a left or right spin with equal probability.

Now for the magic. To conserve angular momentum, after A is measured and so acquires a definite spin, B must acquire the opposite spin. Assume that A, measured in Chicago, has a left spin. (Remember, it does not have a definite spin until measured.) On a planet in a distant galaxy a physicist measures B when it gets there. It is certain to have a right spin. How does B "know" the outcome of the measurement of A? Does A send some kind of telepathic signal to B, either simultaneously or at a speed equal to or exceeding the speed of light? Einstein ridiculed this as "spooky action at a distance." He believed that his proposed experiment, then only a thought experiment, proved that QM was not complete. There must be local "hidden variables" giving definite spins to both particles before one is measured.

The standard Copenhagen interpretation of QM, based on the opinions of Niels Bohr, is that regardless of how far apart A and B get, they remain a single quantum system with a single wave function. When A is measured, the entire system's wave function vanishes and the two particles simultaneously acquire opposite spins. The particles are said to be "correlated," or in more recent terminology, "entangled."

Does this resolve the paradox? It does not. The mystery remains of how A and B can stay entangled when they are light-years apart unless there is some kind of connection between them that allows information to go from A to B.

Experiments have been conducted that appear to confirm this non-locality and it is now generally assumed to be a feature of nature regardless of which interpretation one puts on quantum mechanics.

Nevertheless, one physicist has attempted to propose a local, causal alternative physical theory that explains the quantum mechanical world. Dr. Lewis Little proposes the Theory of Elementary Waves (TEW). Dr. Little also proposes that both waves and particles exists, however, the particles follow waves that originate from a direction opposite to the particle's motion. These "reverse waves" are really a kind of flux. From chapter 1 of Little's upcoming book:

To summarize, the reverse wave theory posits that the physical universe
consists of both waves/fluxes and particles, which are separate objects. These
objects do not transform into one another nor are they the same object in
different states. The waves/fluxes exist at all times; they interact in much the
same manner as quantum waves in current theory. Particles are determined
in their dynamics by the waves/fluxes; but it is only the reverse wave, coming
from any detector (as viewed in the frame of that detector), that a¤ects a
particle that will be observed by that detector.

Because the waves/fluxes exist as separate objects and on the same level
as the elementary particles, I have chosen to call them “elementary waves”,
and I will refer to the flux as the “elementary flux”. [p.39]
At first there seemed to be much excitement within the Objectivist community about Little's ideas. I was certainly among those excited when I first heard about it. The late Objectivist Physicist Stephen Speicher endorsed it and wrote a non-technical summary, David Harriman initially endorsed it in his lecture series The Philosophic Corruption of Physics, and Australian radio broadcaster Prodos provided charts and interviews to further support the ideas.

Then came the dissenters. Physicists Travis Norsen and Eric Dennis pointed out that since TEW fails to explain the latest experiments testing for superluminal or non-local effects. Norsen wrote:
Despite the mistaken claims of TEW's advocates to the contrary, the [experimental] results combined with Bell's theorem prove that no purely local description is possible. These experiments constitute a direct observation of a new type of (superluminal) causation.
Bell's theorem, in the simplest terms can be stated as follows:
no physical theory which is realistic as well as local in a specified sense can reproduce all of the statistical predictions of quantum mechanics [Oxford PhysJoy Christian]
David Harriman released a statement retracting his endorsement of TEW as a result of the arguments made by Norsen, Dennis, and others for for existence of non-local interactions. As Harriman put it:
TEW is a local theory, and therefore it contradicts the results of these experiments. Furthermore, locality is fundamental to Little's theory—to renounce locality is to reject TEW.

Both Norsen and Dennis endorsed the Bohm approach as most promising in providing a causal, yet non-local description of the physics involved. Stephen Speicher and others continued to support TEW and argue that nonlocality involves a contradiction and thus is subject to the same philosophical veto that a denial of causality would be. Betsy Speicher, long time Objectivist and wife of Stephen, published a short essay that argues against nonlocality or "instantaneous action":
...a concept like an "instantaneous action" is metaphysically invalid. Because such an action has no duration, it has no identity, and thus it cannot really exist. It certainly cannot be the underlying metaphysical assumption of a true scientific theory that correctly describes the real world.
I have to say I find this argument quite convincing but feel frustrated by the fact that here is yet another area where seemingly accepted scientific opinion clashes with Objectivism. Norsen has continued to convince other Objectivists including, it seems, Harry Binswanger that nonlocality is real and must be accepted.

Therefore it is somewhat surprising to find the following (unfortunately the article is only available by subscription) in the November 3 issue of NewScientist magazine. Oxford Physicist Joy Christian
...claims that physicists' supposed proofs of the impossibility of more "realistic" theories rest on false assumptions and so don't prove much at all.
"Contrary to the received wisdom," he says, "quantum theory doesn't rule out the possibility of a deeper theory, even one that might be deterministic."
In his latest paper Christian writes:
Contrary to the received wisdom, Bell’s theorem is not a threat to local realism. Neither is it a curb on determinism. The counterexample constructed in the [Dr. Christian's original paper G.R.] provides a fully deterministic, common cause explanation of the EPR-Bohm correlations. In fact, it is hard to imagine a more simple common cause than the one on which the counterexample is based—namely, the intrinsic freedom of choice in the initial orientation of the orthogonal directions in the Euclidean space. In the present paper we have further consolidated the conclusions of [the original paper] by demonstrating that the exact, locally causal model for the EPR-Bohm correlations constructed therein satisfies at least eight essential requirements, arising from either the predictions of quantum mechanics or the premises of Bell’s theorem. These requirements, as listed in the Introduction, include the locality condition of Bell, and hence by respecting them our model fully endorses the view that the quantum mechanical description of reality is incomplete. Moreover, since this view is reinforced by three different local realistic derivations of the violations of the CHSH inequality [a variation on the Bell inequality G.R.], and since all three of them agree with the corresponding predictions of quantum mechanics in quantitatively precise manner, the statistical interpretation of the entangled singlet state becomes the most natural interpretation of this state, as anticipated by Einstein. It is therefore hoped that—strengthened by the results of the present paper—the counterexample of [original paper G.R.]would rejuvenate the search for a unified, locally causal basis for the whole of physics, as envisaged by Einstein.
The actual resolution that Christian offers involves changing the mathematics of Bell's theorem with something called Clifford Algebra of which I am ignorant. Sorely lacking in everything I've read about Dr. Christian's ideas is a physical description of quantum mechanics as a local, deterministic theory. Would it be at all similar to TEW? I guess that remains to be seen. But Christian's papers, along with the recent admission that the Big Bang theory is far from experimentally established give room for some hope that perhaps Objectivists will be finally be able to claim that far from contradicting science, the latest scientific theories support what Objectivism has been saying all along.

Update 11/18/2007 -- Added link Dr. Hans Schantz paper on Quantum Mechanics
Update 10/24/2008 -- Per Lewis Little's request changed description "Objectivist physicist" to "physicist"

14 comments:

Anonymous said...

I don't know about this latest theory you mention, but it was my impression that the discussion on HBL some years ago showed that the Speichers' objections to non-locality were based on a misinterpretation of that notion. The so-called "non-local" interactions described by EPR experiments don't actually need to be instantaneous, they need only be faster than the speed of light. This is a disturbing consequence only for those physicists who dogmatically cling to the most popular interpretation of relativity theory. But as far as I know, there is nothing contradictory or spooky about faster-than-light interactions. They're only spooky to Einstein because they violate his theory. His theory might be wrong.

NS

Gideon said...

Frankly, I'm not so sure. First, I think that the consequences of Einstein's theory being wrong would be a little more momentous than you suggest. After all, it has been verified experimentally at least as much as quantum mechanics. Moreover, I assume you agree that what these EPR experiments suggest is not that Einstein is wrong but that his theory is incomplete or of more limited applicability than perhaps generally assumed. Finally, the physical implications of faster than light interactions are at least as problematic as some of bizarreness coming out of quantum mechanics. After all, it is usually claimed that faster-than-light interactions would involve reversal of cause and effect. Perhaps I simply don't understand the physics well enough. Regardless, I certainly hope the new theory pans out but I would like to hear a more physical description of it.

Kyle Haight said...

I am not a physicist, but I don't think it's really the case that faster-than-light travel would reverse cause and effect. Rather it would mean that the effects of a superluminal cause could reach us before any lightspeed-restricted information about that cause could reach us. This would put us in the position of seeing an effect before we see the cause, but that's an epistemological issue rather than a metaphysical one. It's no different in principle from the way we see the flash of lightning before we hear the thunder.

Things would break down more severely if we move from merely superluminal causation to instantaneous causation. In that case, the cause of an effect we perceive locally could be literally anywhere else in existence. It seems like that would pose some pretty serious problems for identifying the cause of any given effect. I have the impression that the existing EPR experiments allegedly require superluminal causation but not instantaneous causation.

Still, this does look like an interesting development and I'd be interested in an assessment of its significance by an Objectivist with professional physics training.

Gideon said...

I just sent an email to HBL asking physicists there to comment on Joy Christian's claims.

Ken Barclay said...

I have followed the history of cosmology as seen by Objectivists for years. Your clear summary, all in one place, is very welcome. It must have taken considerable work to put all this together. Thank you.

Gideon said...

You're very welcome! It did take some work but since, like you, I have followed Objectivist views on physics for many years I knew what I wanted to put together. I was a physics major when I became an Objectivist and even though I did not pursue a graduate degree in physics, I suspect this topic will always be of interest to me.

BetsySpeicher said...

Gideon wrote:

In his latest paper Christian writes:

Contrary to the received wisdom, Bell’s theorem is not a threat to local realism. Neither is it a curb on determinism. The counterexample constructed in the [Dr. Christian's original paper G.R.] provides a fully deterministic, common cause explanation of the EPR-Bohm correlations.

So did my late husband and Dr. Lewis Little from the point of view of the TEW.

As for the scientific validity of Harriman's critique, it was discussed at length on the TEWLIP discussion list and you can read it all by going to here and entering "Bell's inequality" or "DDC" in the search box at the top of the page.

The one posting with links to Lewis Little's explanation of the Double Delayed Choice (DDC) experiment in terms of the TEW, Travis Norsen's critical comment, and Stephen Speicher's response to Norsen's comment, can be read here.

Gideon said...

Betsy writes (with respect to providing a deterministic causal explanation of EPR Bohm experiments):
So did my late husband and Dr. Lewis Little from the point of view of the TEW.

I did mention Little's TEW and Stephen's support for it. And I remain sympathetic (sympathetic, but not convinced, nor am I convinced by the "other side" -- frankly I remain confused on the entire issue -- I do hope one day to acquire enough physics expertise to resolve the confusion). The primary difference at present is that Christian is apparently getting a hearing in a mainstream publication such as Physical Review Letters, whereas unfortunately so far Dr. Little only got published in Physics Essays. Perhaps if Christian manages to convince the physics community that a local causal explanation is possible it will open up the door to allow Little's ideas to be taken a little more seriously.

I will say in Little's defense that it's still the only explanation I'm aware of that presents a clear picture of what's going on in both quantum mechanics and special relativity.

Anonymous said...

There is an excellent book that explains Bell's theorem and the DDC experiments, as well as its implications for special relativity. The book is "Quantum Non-Locality and Special Relativity" by Tim Maudlin. It does not require any advanced math or physics to understand. It is very accessible. There is also an appendix on the Bohm interpretation, which Maudlin supports. He says quite a few things about the standard interpretation which I think an Objectivist would find refreshing.

M

Gideon said...

I have not heard of Maudlin's book but it looks very interesting. I'll see if I can read it when I get a chance. Thanks for the recommendation!

Gideon

Anonymous said...

if it matters at all, Hans Schantz's paper (in two parts) "Philosophic Premises of Quantum Mechanics" can be retrieved from the Internet Archive: use www.archive.org/web/web.php and search on www.schantz.com/quantum.htm

Brewster Kahle gets at least one gold star...

Gideon said...

It does matter -- Thanks! The link to Dr. Schantz's papers is here. I'll make the change above. Good to know about that archive site!

Gideon

Mark said...

You needn’t puzzle over locality in order to reject TEW. TEW is incomplete at a basic level, in other words it’s no theory at all — as I argued on the now defunct Yahoo discussion group TEWLIP. You can read one of my posts here and search for the others.

Mark
ARI Watch

BetsySpeicher said...

> Mark said...
> You needn’t puzzle over locality
> in order to reject TEW. TEW is
> incomplete at a basic level, in
> other words it’s no theory at
> all — as I argued on the now
> defunct Yahoo discussion group
> TEWLIP. ....

If you want to assess the value -- or even the sanity -- of Mark's arguments, check out his own web site that he links to in his .sig

> Mark
> ARI Watch

There you will find the following:

"On this website you will read ARI writers advocating the expedient suspension of the U.S. Constitution, self-sacrifice, and torture. You will see their evasions, their sickening aping of Ayn Rand’s style of expression, their sophistries and lies. You will see this as they call all who disagree with them pragmatists, leftists, and America-haters. We hang them by their own utterance and offer comment.

Vice is ugly, but it does one good to see it properly labeled. Our aim is to create a place where honest students of Ayn Rand, sickened by ARI, can come to recuperate."