ENTANGLEMENT NECESSARY TO ANY CLASSICAL THEORYSeptember 15, 2017
Ms. K.M. shared this one from our friends at phys.org, and it is, if I may employ the expression, a whopper-doozie if it should prove to be the case.
But first, a bit of background by way of an all-too-brief excursion through the history of science. One of the revolutionary things that Christianity did was to lay a metaphysical foundation for "natural philosophy," which is what the Middle Ages and the early enlightenment would now call "physics." I've long suspected that the older term was, perhaps, a more accurate one, for it acknowledged the presence of implicit metaphysical and cosmological assumptions were at the core. In the milieu in which Christianity appeared, the common assumption - with many variations to be sure - was that the natural order was comprised of "levels", each with their own special laws of operation: the heavens obeyed heavenly laws, the Earth terrestrial ones. The Greeks began a process of the unification of all of these levels under reason, or logos, and Christianity more or less cemented this process by insisting that the Hightest Logos became incarnate in "lowest flesh" as it were, and thus, the metaphysical Grundwerk was laid for the idea that all levels of reality obeyed more or less the same natural logoi (small logoses, or "laws" or "rational principles"). From this it was but a short epistemological and metaphysical conclusion (coupled with a very long historical development) as the principles were worked out, but basically, we may boil this whole complex and almost infinitely detailed and at times frustrating process down to the corollary that if all this was true, then observations made of certain physical phenomena here on earth could be extrapolated to the cosmos itself. Universal physical laws became "universe-al" or applicable on a cosmological scale.
But this remained, as will be evident, a metaphysical assumption...until now:
Entanglement is an inevitable feature of reality
Now I am going to assume for a moment that most people here are vaguely familiar with the related phenomena of entanglement and non-locality, i.e., the idea that if two particles with completely identical information are "launched" from a particular point in space-time, that regardless of how far apart they become, that alteration in the information set of one will produce the identical or conjugate alteration in the information set of the other, instantaneously and regardless of distance. The paper in question, however, goes on to build this out, as it were, as the physical underpinning of the metaphysical assumption I all-too-cursorily sketched above: namely, that if one is to make any system of cosmological laws, one must have entanglement as its central component. The article outlines this argument as follows:
Although the full proof is very detailed, the main idea behind it is simply that any theory that describes reality must behave like classical theory in some limit. This requirement seems pretty obvious, but as the physicists show, it imparts strong constraints on the structure of any non-classical theory.
Quantum theory fulfills this requirement of having a classical limit through the process of decoherence. When a quantum system interacts with the outside environment, the system loses its quantum coherence and everything that makes it quantum. So the system becomes classical and behaves as expected by classical theory.
Here, the physicists show that any non-classical theory that recovers classical theory must contain entangled states. To prove this, they assume the opposite: that such a theory does not have entanglement. Then they show that, without entanglement, any theory that recovers classical theory must be classical theory itself—a contradiction of the original hypothesis that the theory in question is non-classical. This result implies that the assumption that such a theory does not have entanglement is false, which means that any theory of this kind must have entanglement.
This result may be just the beginning of many other related discoveries, since it opens up the possibility that other physical features of quantum theory can be reproduced simply by requiring that the theory has a classical limit. The physicists anticipate that features such as information causality, bit symmetry, and macroscopic locality may all be shown to arise from this single requirement. The results also provide a clearer idea of what any future non-classical, post-quantum theory must look like.
In short, the work has breathtaking implications, for if this method is successful in these other areas, then what was once a metaphysical assumption inherited from Greece and Christianity will no longer be a metaphysical assumption about science, but rather, the sine qua non proven necessity for "natural philosophy," that is, for its very occurrence itself. If so, then it will remake not only physical science or "natural philosophy", but cast an entirely new philosophical light on its historiography.
See you on the flip side...