Pun Salad

I don't remember why I put this book on my get-at-library list. (I really should keep notes.) And (as it happens) my current mode of library-interaction (as it were) is to check a book's availability online (or get it through Interlibrary Loan), and my physical presence onsite (as it were) is a quick in-and-out. Browsing (as I might have done pre-Covid) is discouraged.

The above paragraph apes the style of the author of Time and Chance, David Z. Albert. Lots of random parenthetical asides that don't add much information, lots of random italics. The book reads as if it were a transcript of chatty oral presentations of a particularly animated and eccentric sort. And it can get pretty impenetrable at times, by which I mean nearly always. Here's a sample paragraph from page 62:

I’ve been talking about the postulate about statistics up to now as if it more or less amounted to a stipulation that what you ought to suppose, for purposes of predicting a system's future behavior, if you are given only the information that the system initially satisfies X, is that the system is as likely to be in any one of the microconditions compatible with X at the initial time in question as it is to be in any other one of the microconditions compatible with X at the initial time in question. That’s more or less what the postulate amounts to (I think) in the imaginations of most physicists. And that (to be sure) has a supremely innocent ring to it. It sounds very much—when you first hear it—as it is instructing you to do nothing more than attend very carefully to what you mean, to what you are saying, when you say that all you know of the system at the time in question is X. It sounds very much as if it is doing nothing more than reminding you that what you are saying when you say something like that is that X is the case at the time in question, and (moreover) that you have no more reason for believing that the system is in any particular one of` the microconditions compatible with X at the time in question than you have for believing that it is in any other particular one of the microconditions compatible with X at the time in question, that (insofar as you know, at the time in question) nothing favors any particular one of those microconditions over any particular other one of them, that (in other words) the probability of any particular one of those microconditions obtaining at the time in question, given the information you have, is equal to the probability of any particular other one of them obtaining at the time in question.

I was very much in "I looked at every page" mode for large swaths of the book. I would flunk badly if quizzed on its details. It's a slim book, I tried to tackle a mere ten pages/day, but…

Anyway: Albert has his Ph.D. in theoretical physics but moved over to the philosophy department at Columbia. The book deals with time's arrow, or: exactly how do we distinguish the past from the future?

The problem being that many (but not all) of the physical laws of the universe are invariant under time-reversal. For example, if you had a movie of the planets revolving around the sun, then played that movie backward, the planets would still seem to be obeying, blissfully, the same Newtonian laws of motion. Similarly for gas molecules in a box: they bounce off each other, and the walls of the box, elastically, and they would appear to do the same thing in a time-reversed movie. You couldn't really tell whether you were watching the movie backwards or forwards.

Fine, but that's completely at odds with our everyday experience. We can nearly always tell when a movie's running backward: when we dominoes spontaneously rising into a complex pattern instead of falling, gases collapsing into a corner of a box instead of expanding to fill the available volume, stars sucking up light, instead of emitting it, etc. "That ain't right."

So the book immediately gets into matters of thermodynamics, entropy, and statistical mechanics. But Albert notes that the underpinnings of those fields and concepts are epistemologically shaky, and attempts to firm them up. And he may do so, but don't ask me.

In the latter parts of the book, he brings in quantum mechanics, which may help things. He discusses several interpretations, and holds up one for special attention: the Ghirardi–Rimini–Weber (GRW) theory. I think that's pretty obscure, but not obscure enough to lack a Wikipedia entry.

So: my bad. If I ever had the physics chops to follow Albert's argument, they're gone now. And in the future, I'll try to have a solid Plan B in place when getting a library book.