Tuesday, August 23, 2022

Existential Physics: A Scientist's Guide to Life's Biggest Questions

I just finished this new book by Sabine Hossenfelder. It has similarities to her last book, Lost in Math: How Beauty Leads Physics Astray, which focused on how physicists entertain exotic theories that are difficult to link to actual observable events, and how this emphasis on mathematical aesthetics is contributing to a slump in the development of useful new theories. The new book continues the pragmatic emphasis of the last book, but covers a broader range of topics. Although Hossenfelder writes clearly and concisely, the subjects are quite abstruse, so, whether she likes it or not, the content is way over the heads of most readers, though, if they make an effort, they may get the gist of it. Even so, though I think it's much more interesting than A Brief History of Time, Stephen Hawking's bestseller, I don't think it will sell as well. That is probably one of the least-read books on people's bookshelves. From a marketing standpoint, it might have helped if she had ALS and used a speech synthesizer. However, Hossenfelder has already established herself as a credible science pundit, and this book will enhance her career.

Some of the topics interested me more than others, and I'll focus on those. As in the last book, there are interviews, but I didn't find them enlightening. They are entertaining when, for example, she critiques her host's housekeeping and hints that she may dislike men with long hair. Some of the subjects are difficult, and covering them in brief chats doesn't do them justice, though her publisher probably encouraged her to keep it as light as possible. She seems more confident in her interviews than before, when, for example, she was intimidated by Steven Weinberg, but I doubt that she will ever rake an interviewee over the coals. In some ways, she is refreshing, because she doesn't have a gigantic male ego and is simply attempting to educate people.

Chapter 2 is "How Did the Universe Begin? How Will it End?" In this chapter, Hossenfelder concludes that we may never know. To me, some related questions are "How many universes are there?," "Are universes structurally similar?," and "Can the laws of physics in a particular universe change?" I don't think that we will ever know anything about this, except in the sense that we may eventually discover that the laws of physics in this universe are constant. I dislike the psychological impact of these kinds of questions because, if we want to think that our lives are significant, what if there is an infinite number of lives, and an infinite number of those lives are identical to yours? This hardly boosts one's sense of importance. In one universe, your equivalent may have made a slightly different decision, and the consequences may have been significant. I'd rather not think about it.

Chapter 6 is "Has Physics Ruled Out Free Will?" Hossenfelder concludes:

According to the currently established laws of nature, the future is determined by the past, except for the occasional quantum events that we cannot influence. Whether you take that to mean that free will does not exist depends on your definition of free will.

Although I'm hardly qualified on this topic, my feeling is that it is possible that "quantum events" may also be found to fit a yet-to-be-discovered deterministic model. This would mean that everything that has occurred in this universe was predetermined, i.e., free will does not exist.

"Is Consciousness Computable?" is an interview with Roger Penrose. Penrose thinks that consciousness may not fit within a deterministic model. I think that it does. This is one of the areas in which physicists are prone to making mistakes. My feeling is that physicists are not generally competent in biology. I think, for example, that most mammals have a consciousness quite similar to ours. This means that, if consciousness is unique, we're no more unique than chipmunks. One of the main themes throughout human history has been to show how humans are somehow superior to other animals. We're not that different. I think that Roger Penrose has seen better days as a thinker.

Consciousness is also discussed in Chapter 8. There, Hossenfelder makes a good point in a rather amusing way:

We don't yet know exactly how to define consciousness, or exactly which brain functions are necessary for it, but its a property we observe exclusively in physical systems. Because, well, we observe only physical systems. If you think your own thoughts are an exception to this, try thinking without a brain. Good luck.

In some respects, Hossenfelder is more tolerant of ideas that she disagrees with than I am. For example, she doesn't agree with Nick Bostrom's idea that the universe could be computer simulation. I agree with her and would not even have bothered to discuss Bostrom's ideas. Similarly, although she is not religious, she is reluctant to criticize religious people. My view is that religions serve an evolutionary purpose for humans. Historically, we have needed them both to help maintain cohesive groups and to provide a kind of assurance of our place in the universe, given that we are conscious and the answers are beyond our comprehension. I think that Hossenfelder's understanding of evolution is similar to mine, but that, because she is not a biologist, she may not understand all of the implications of being a biological entity. To me, this means that everything about us has come to be for survival reasons. Physicists tend to see mathematics as an objective way to discuss reality, whereas I see it as an evolutionary development that is dependent on biology for its existence.  In my view, mathematics exists only because humans communicate with language, and mathematics is the most precise language that we've developed. I would not have given space to Max Tegmark, who thinks that the universe is a mathematical entity. In the books I've discussed by Frans de Waal and Giorgio Vallortigara, evidence is provided that other animals are conscious and even have rudimentary mathematical skills. My interpretation is that consciousness is nothing special and is simply a byproduct of sophisticated brains. Without evolution, mathematics would not exist.

I should mention an anecdote that I read many years ago. When asked how he came up with an idea, Einstein described how he had an odd sort of physical reaction when it occurred to him. It had nothing to do with mathematics, and sounded to me like an intuitive insight. The process of expressing it mathematically was separate, and sometimes he needed help with that.

One area that Hossenfelder doesn't specifically discuss is morality. For me, it is important to understand that morality is also a product of evolution. I have been writing about this for several years now and am amazed that no one else seems to have this opinion. A lot of time could be saved by ignoring philosophical treatises on morality, free will and consciousness. Contemporary physics pundits can get into ruts if they indulge their philosophy colleagues too much.

Towards the end of the book, there is a discussion of AGI, and Hossenfelder's views are similar to mine. I think the main danger is that it will fall into the wrong hands, not that it will inherently be a menace to us.

On the whole, I found reading this book to be an interesting and challenging exercise. However, if you're like me, you may not have anyone to discuss it with. Most people never think about these topics, and they can be quite scary.