Rovelli 6: It's all about information.

This is my sixth and final post on Carlo Rovelli's new book, Reality Is Not What It Seems. The first three posts were:

• From Democritus to Relativity to Quantum Mechanics
• Spacetime is Quantum
• Quanta of Space
• Time Does Not Exist
• Fundamental Constants of the Universe

1. Finished the book a few days ago. Chapters 12-13 look somewhat vaguely to the future. I frankly didn't get much out of them. In chapter 12 he tries to give a general sense of what he means by a "relational" interpretation of quantum mechanics (QM). He references this Stanford article. "The notion of the 'state' of a system refers, explicitly or implicitly, to another system" (253).

So he boils QM to two postulates: 1) The relevant information in any physical system is finite and 2) You can always obtain new information on a physical system. John Wheeler, the father of quantum gravity once said, "everything is information."

2. The main thing of interest is the question of time. He gives a "thermal" interpretation of time. All the processes of the universe are reversible (and thus time irrelevant) except for those that involve heat and entropy. "There is no preferred direction of time without heat" (251). "The origin of time may be similar to that of heat: it comes from averages of many microscopic variables" (250).

I did gain from this book, but it did leave me hanging. So I move on to more books...