Nicolas Gisin is an experimental physicist who has extended the tests of quantum entanglement and nonlocality (the EPR experiment) to many kilometers from his lab in Geneva. His work has confirmed the correctness of quantum mechanics, and with it the irreducible indeterminacy involved in quantum mechanical measurements. Gisin is the recipient of the first John Stewart Bell prize. It is Bell's Theorem and the Bell Inequalities that Gisin's work has confirmed. Despite his critical work that grounds quantum physics, Gisin has been active in searching for alternative mathematical formulations of quantum theory, especially ones that might replace the ad hoc assumption of wave functions "collapsing" when measurements are made. Alternatives proposed by GianCarlo Ghirardi and his colleagues replace the linear Schrödinger equation for the time evolution of the wave function with a nonlinear equation that includes explicit stochastic terms. Gisin also has explored the paradoxical interpretations of his nonlocality experiments. The perfect nonlocal correlation of distant spin states suggests that information is traveling between the two widely separated measurements of electrons in an entangled spin state at velocities greater than the speed of light. This is of course impossible, but Gisin speculates that some "influence" may be affecting both experiments coming from "outside space and time." Gisin says he means by this that "there is no story in space and time" to account for nonlocality. This is of course because the collapse of probabilities is instantaneous (not therefore "in time?") and happens everywhere (surely "in all space?"). If there were such influences, they might provide an explanation for deterministic theories, "some sort of hyper-determinism that would make all Science an illusion," says Gisin. He explains:
We have seen that any proper violation of a Bell inequality implies that all possible future theories have to predict nonlocal correlations. In this sense it is Nature that is nonlocal. But how can that be? How does Nature perform the trick? Leaving aside some technical loopholes, like a combination of detection and locality loopholes, the obvious answer, already suggested by John Bell, is that there is some hidden communication going on behind the scene. A first meaning of "behind the scene" could be "beyond today's physics", in particular beyond the speed limit set by relativity. We have seen how this interesting idea can be experimentally tested and how difficult it is to combine this idea with no-signaling. Hence, it is time to take seriously the idea that Nature is able to produce nonlocal correlations. There are several ways of formulating this: 1. Somehow God plays dice with nonlocal die: a random event can manifest itself at several locations. 2. Nonlocal correlations merely happen. somehow from outside space-time, in the sense that no story in space-time can describe how they happen. 3. The communications behind the scene happens outside space-time 4. Reality happens in configuration space: what we observe is only a shadow in 3-dimensional space (this might be closest to the description provided by standard quantum physics).
Free willGisin says about free will,
Descartes pineal gland. In standard quantum physics such an interface between free will and physics could be even simpler: free will could influence the probabilities of quantum events. This is, admittedly, a vague and not very original idea; but important is that there is no obvious definite contradiction between free will and standard quantum physics.I know that I enjoy free will much more than I know anything about physics. Hence, physics will never be able to convince me that free will is an illusion. Quite the contrary, any physical hypothesis incompatible with free will is falsified by the most profound experience I have about free will. So, would I have rejected Newtonian classical mechanics had I lived before quantum physics? Probably not. Indeed, classical physics leaves open the possibility that free will can somehow interface with the deterministic Newtonian equations: free will could set-up some potential that could slightly influence particles's motion. This would be something like
For ScholarsThe experimental setup for quantum entanglement tests is theoretically simple but experimentally difficult. Two spin 1/2 electrons are prepared in a state, say with opposing spins so the total spin angular momentum of the electrons is zero. They are said to be in a singlet state. Most recent studies, like Gisin's, used entangled polarized photon pairs.) Two experimenters (call them A and B) measure the electron spins at some later time. The conservation of angular momentum requires that should one of these electrons be measured with spin up, the other must be spin down. This is what is described as "nonlocal" correlation of the spin measurement results. A simpler way of looking at the problem is to consider the conservation of angular momentum, a law of nature that can not be violated. What would the lack of "correlation" between electron spins look like? It would include some spin-up measurements by experimenter A at the same time as spin-up measurements by experimenter B. But this is a clear violation of the conservation law for angular momentum. This conservation law in no way depends on supra-luminal communications between particles. Consider two electrons at opposite ends of the Andromeda galaxy, say 100,000 light years apart. As they revolve around the center of the galaxy, they conserve their orbital angular momenta perfectly. We might say that conservation laws are "outside space-time." Note that the original EPR thought experiment involved particles going in opposite directions from a central source. In that case the governing conservation law was for ordinary translational momentum.
Are Real Numbers Really Real?In 2018 Gisin speculated on the "reality" of real numbers. He suggested:
Since a finite volume of space can’t contain more than a finite amount of information, I argue that the mathematical real numbers are not physically real. Moreover, a better terminology for the so-called real numbers is “random numbers”, as their series of bits are truly random.Information philosophy regards the mathematical numbers continuum as purely immaterial information. Information is physical, but not material. What is limited and finite in a finite volume of space is the number of discrete material particles. Gisin proposes an "alternative classical mechanics" based on this finite amount of information. He says it would be non-deterministic, similar to quantum mechanics, though it could be supplemented with additional variables (e.g., the continuum of real numbers, including the infinite numbers of numbers, irrational, etc.) to restore determinism. A finite volume of space can be described by an infinite mathematical field, but it can hold only a finite number of discrete material particles. Field theories appear to contain an infinite amount of information. Moreover, they involve infinitesimal points which appear to be singular points, describable by infinite "delta functions" (whether Kronecker or Dirac). A finite number of particles, on the other hand, may need only a finite number of algebraic equations. Albert Einstein was puzzled by the connection between the infinite continua used to describe space and time with continuous differential equations and the finite discrete picture of difference equations. Einstein wondered if an algebraic approach, one that describes discrete material particles rather than continuous immaterial fields, might be adequate for quantum mechanics. Einstein's explained how continuous field theories came to be a part of our description of reality - alongside material particles - as a result of Maxwell's equations - in his 1931 article "Maxwell's Influence on the Evolution of the Idea of Physical Reality." A few years later, he again questioned whether continuous theories, with their infinities and singularities, would be the final answer to what is real.
In the Schrodinger equation, absolute time, and also the potential energy, play a decisive role, while these two concepts have been recognized by the theory of relativity as inadmissible in principle. If one wishes to escape from this difficulty, he must found the theory upon field and field laws instead of upon forces of interaction. This leads us to apply the statistical methods of quantum mechanics to fields, that is, to systems of infinitely many degrees of freedom. Although the attempts so far made are restricted to linear equations, which, as we know from the results of the general theory of relativity, are insufficient, the complications met up to now by the very ingenious attempts are already terrifying... To be sure, it has been pointed out that the introduction of a space-time continuum may be considered as contrary to nature in view of the molecular structure of everything which happens on a small scale. It is maintained that perhaps the success of the Heisenberg method points to a purely algebraical method of description of nature, that is, to the elimination of continuous functions from physics. Then, however, we must also give up, on principle, the space-time continuum... In view of this situation, it seems to be entirely justifiable seriously to consider the question as to whether the basis of field physics cannot by any means be put into harmony with quantum phenomena. Is this not the only basis which, with the presently available mathematical tools, can be adapted to the requirements of the general theory of relativity? The belief, prevailing among the physicists of today, that such an attempt would be hopeless, may have its root in the unwarranted assumption that such a theory must lead, in first approximation, to the equations of classical mechanics for the motion of corpuscles, or at least to total differential equations. As a matter of fact, up to now we have never succeeded in a field-theoretical description of corpuscles free of singularities, and we can, a priori, say nothing about the behavior of such entities. One thing, however, is certain: if a field theory results in a representation of corpuscles free of singularities, then the behavior of these corpuscles in time is determined solely by the differential equations of the field.To Leopold Infeld he wrote in 1941,
"I tend more and more to the opinion that one cannot come further with a continuum theory."Einstein in his later years grew even more pessimistic about the possibilities for deterministic continuous field theories, by comparison with indeterministic and statistical discontinuous particle theories like those of quantum mechanics. He wrote his friend Michele Besso in 1954 to express his lost hopes for a continuous field theory like that of electromagnetism or gravitation,
"I consider it quite possible that physics cannot be based on the field concept, i.e:, on continuous structures. In that case, nothing remains of my entire castle in the air, gravitation theory included, [and of] the rest of modern physics."The fifth edition of The Meaning of Relativity included a new appendix on Einstein's field theory of gravitation. In the final paragraphs of this work, his last, published posthumously in 1956, Einstein wrote:
Is it conceivable that a field theory permits one to understand the atomistic and quantum structure of reality ? Almost everybody will answer this question with "no"... One can give good reasons why reality cannot at all be represented by a continuous field. From the quantum phenomena it appears to follow with certainty that a finite system of finite energy can be completely described by a finite set of numbers (quantum numbers). This does not seem to be in accordance with a continuum theory, and must lead to an attempt to find a purely algebraic theory for the description of reality. But nobody knows how to obtain the basis of such a theory.Finally, we should note that Einstein was greatly impressed by the work of two great mathematicians, Leopold Kronecker and Richard Dedekind. Kronecker famously argued that the continuum is a human creation. He said, "God made the integers, all else is the work of man." ( "Die ganzen Zahlen hat der liebe Gott gemacht, alles andere ist Menschenwerk"). Kronecker gained a measure of control over the infinities and singularities of continua with his "Kronecker delta," which is infinitely tall but infinitesimally wide, like Paul Dirac's later delta function, it integrates to unity. A few years later, Dedekind echoed Kronecker, saying "the negative and fractional numbers have been created by the human mind." (Essays on the Theory of Numbers, p.4) Dedekind was the source for one of Einstein's most famous phrases, the "free creation of the human mind" "Physical concepts are free creations of the human mind, and are not, however they may seem, uniquely determined by the external world." From Information Philosophy All the fields of physics, gravitation, electromagnetism, nuclear, and even the quantum wave function, are descriptions that enable accurate predictions of the properties of a test particle at a pint in the field. As such, fields are abstract, immaterial, information about concrete, material, objects. In the case of quantum mechanics, the wave function provides only statistical information about individual particles. Quantum theory is thus a statistical, and therefore incomplete theory, as Einstein knew well, though his colleagues all dismissed his thinking. See http://www.informationphilosopher.com/solutions/scientists/einstein/ for more. -->
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