Wednesday, November 4, 2015

More on Musser's spooky book

SciAm editor George Musser complains that I trashed his book without reading it. Okay, fair point. His book is on Amazon as Spooky Action at a Distance: The Phenomenon That Reimagines Space and Time -- and What It Means for Black Holes, the Big Bang, and Theories of Everything.

The endorsement from Frank Wilczek says:
Locality has been a fruitful and reliable principle, guiding us to the triumphs of twentieth-century physics. Yet the consequences of local laws in quantum theory can seem 'spooky' and nonlocal-and some theorists are questioning locality itself. Spooky Action at a Distance is a lively introduction to these fascinating paradoxes and speculations.
Wilczek is a distinguished and level-headed physicist. I read this as saying that he firmly believes in locality as a great triumph of XX century physics. Some quantum experiments may seem spooky and nonlocal, so they are fun to talk about, but he is not endorsing any spooky or nonlocal interpretations or speculations that are in the book.

I can agree with that. Maybe Musser put "spooky" in the title to sell more books. If so, I do not fault him for that, as long as he describes the physics correctly.

I was once appalled by a 1979 book called The Dancing Wu Li Masters: An Overview of the New Physics. While the book was filled with goofy speculations, the actual description of the known physics was pretty accurate. So I ultimately decided that it was a decent book.

The current SciAm has a preview of his book, where he relates nonlocality to general relativity:
When I first learned about the quantum phenomenon known as nonlocality in the early 1990s, I was a graduate student. But I didn't hear about it from my quantum-mechanics professor: he didn't see fit to so much as mention it. Browsing in a local bookshop, I picked up a newly published work, The Conscious Universe, which startled me with its claim that “no previous discovery has posed more challenges to our sense of everyday reality” than nonlocality. The phenomenon had the taste of forbidden fruit. ...

Points in the gravitational field must be interlinked with one another so that they can flop around while collectively still producing the same internal arrangement of objects. These linkages violate the principle that individual locations in space have an autonomous existence. Marolf has put it this way: “Any theory of gravity is not a local field theory. Even classically there are important constraint equations. The field at this point in spacetime and the field at this point in spacetime are not independent.” ...

In short, Einstein's theory is nonlocal in a more subtle and insidious way than Newton's theory of gravity was. Newtonian gravity acted at a distance, but at least it operated within a framework of absolute space. Einsteinian gravity has no such element of wizardry; its effects ripple through the universe at the speed of light. Yet it demolishes the framework, violating locality in what was, for Einstein, its most basic sense: the stipulation that all things have a location. General relativity confounds our intuitive picture of space as a kind of container in which material objects reside and forces us to search for an entirely new conception of place.
I have no quarrel with this, except that I would not use the word "locality" this way. To me, locality means that the physics of a point can be understood from tevents, matter, and fields in its local neighborhood. General relativity satisfies locality in that sense. Musser says that relativity makes a global definition of location more difficult. Yes, that's right, but I would say that is a consequence of locality, not a contradiction to locality.

Update: Motl has just posted a good explanation of locality, and why it is a mistake to give up locality in order to get a more intuitive understanding of quantum mechanics. The spookiness of nonlocality is always less intuitive. I will respond to the first comment below tomorrow.

1 comment:

  1. I think that's a fair point. The meaning of the word "locality" is contentious and in the book I adopt a fairly broad definition. I certainly wouldn't want to be understood as implying a violation of relativistic causality, and I do have a good deal of discussion of this issue.