Quantum Non-Locality and Relativity: Metaphysical Intimations of Modern Physics

Quantum Non-Locality and Relativity: Metaphysical Intimations of Modern Physics

by Tim Maudlin

Modern physics was born from two great revolutions: relativity and quantum theory.

Relativity imposed a locality constraint on physical theories: since nothing can go faster than light, very distant events cannot influence one another.

Only in the last few decades has it become clear that quantum theory violates this constraint.

S. Bell has demonstrated that no local theory can return the predictions of quantum theory.

Quantum Non-Locality and Relativity examines the nature and possible resolution of this conflict.

Beginning with accurate but non-technical presentations of Bell's work and of Special Relativity, there follows a close examination of different interpretations of relativity and of the sort of locality each demands.

  • Language: English
  • Category: Philosophy
  • Rating: 4.56
  • Pages: 281
  • Publish Date: February 11th 2002 by Blackwell Publishers
  • Isbn10: 0631232214
  • Isbn13: 9780631232216

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Did these reviewers actually bother reading through the book properly or did they just skim the surface of Maudlin's exposition and go, "Oh! The first two chapters are fine - I remember feeling very happy with what I was reading, and pleased that the mathematics regarding polarizers and Lorentz transformations were simple enough to handle; but by the time I got to chapters 3 and 4, the reading experience just became incredibly tiresome and frustrating when I would have to wade through terminologies and new concepts like "Godel's Universe", "commutators" etc., stuff which was just thrown into the discussion in a very ad hoc manner, and this was incredibly offputting because as a reader who only has a rather general understanding of physics (I have some mathematical background and I did the PHYS 130s sequence in UChicago), I was already having to put in a decent amount of effort into trying to (1) follow Maudlin's arguments, and (2) keep the bigger picture in mind. For instance, in Chapter 3, Maudlin explains why particles cannot accelerate beyond the speed of light by the following: "Furthermore, as the velocity approaches the speed of light, the mass approaches infinity, and hence it requires unbounded amounts of energy to get the particle to go faster. Given that only finite amounts of energy are available, it would follow that no particle which travels below the speed of light can ever be accelerated to, or beyond, that speed. 65) Now, intuitively, given his earlier explanation about why particles cannot travel beyond the so-called light barrier (e.g. it would require infinite amounts of energy to offset the infinite increase in mass), wouldn't Tachyons face the same problem as well? Why does it require infinite amounts of energy to accelerate subluminal particles near light speed but Tachyons are able to travel at superluminal velocities just fine? I want to point out a tiny lemma which Maudlin uses to create the bounds of the generalised form of Bell's inequalities: "If x, x, y and y are all numbers that lie between -1 and 1 (inclusive), then the quantity xy + xy + xy - xy lies between -2 and 2 (inclusive)" Maudlin's proof of this lemma appeals to how the given equation is a linear function of its four variables and how it takes its extreme values at the extreme ends of its domain. I think, for all its sins, it's a book that has moments of clarity and does a lot of useful conceptual housekeeping, particularly when it comes to taking stock of the physicists' attempts to design a relativistic theory that accommodates the violations of Bell's Inequalities (e.g. John Cramer's backward-and-forward hypothesis, many-minds ontology, relativistic flashy GRW etc.), and always making sure to identify what epistemic price we pay by opting for one interpretation of the results over another. The structure of this book is also sensible, which is certainly a plus; these chapters build upon each other and explore different nooks and crannies in trying to weld together a coherent interpretation of the physical universe given the presentation of the problem in Chapter 1. (Also, for some reason, I found Maudlin a little less stingy when it comes to providing the general reader with intuition in this chapter - perhaps it might've been because I already went through the fire of the earlier chapters, so I found the material less frustrating, but I think that Maudlin did make a conscientious effort to reduce the opacity of his exposition.

The last chapter also describes a recent discovery: the "flash ontology" for GRW theory (a stochastic dynamical collapse quantum theory) seems to provide a Lorentz invariant description of Bell inequality violation.

More sophisticated understanding of this and a few other issues are only needed if one wishes to follow the defensive arguments the author mounts against potential attacks from his peers. Substance: The author shows quite convincingly that the violations of Bell inequality (and the broader issue that was tersely represented by Bell) create deep problems (although a few claimed problems are dismissed with equal authority).

Perhaps the greatest part of the book is that it delves into questions that usually physicists tend to either brush off or be completely ignorant about, that is to say the nature and compatibility of both theories in physics.

This does not mean that the book is not demanding, it definitely is for those with no prior knowledge about quantum mechanics and relativity!