Tuesday, December 29, 2020

Seven Brief Lessons on Physics by Carlo Rovelli

 Source of book: Borrowed from the library.


I actually borrowed this book for two reasons. First, Peter Enns keeps recommending it as a quick and to the point introduction to the major discoveries in physics in the last 100 years. Although I am already familiar with the topics themselves, I figured I should read it and see if it is worth recommending to others for similar reasons. But also because my twelve year old is currently devouring books as fast as I can bring them home, and he is fascinated with science right now. (Also with Patrick O’Brian…) 

The book lives up to its reputation. In a mere 81 pages, it covers Relativity, Quantum Mechanics, the size and age of the universe, subatomic particles, theories of spacetime that try to reconcile Relativity with quantum mechanics, and a handful of other more esoteric fundamental questions, such as humanity’s place in the universe. Although Rovelli wrote it in Italian, the English translation (by Simon Carnell and Erica Segre) reads smoothly yet precisely. Neither translator appears to have a background in physics, but they clearly did their homework to make sure the concepts came through exactly in the translation. 


As I mentioned, I was already familiar with the concepts both from academic learning and from some great books I have read over the last few years. In fact, here are the ones that come to mind on these topics:


How Old is the Universe? by David Weintraub

The Hunt for Vulcan by Thomas Levenson

The Little Book of Black Holes by Steven Gruber and Frans Pretorius

Reading the Rocks by Marcia Bjornerud

Death From the Skies by Philip Plait


That said, the book is a worthwhile one, particularly for introducing people who don’t tend to pick up 500 page books on science, but want a basic idea of what the heck physicists are talking about. Rovelli (and translators) make the topics come alive, with writing that is beautiful as well as precise. 


I did note a few quotes. First is in the section describing the disagreement between Einstein and Niels Bohr over quantum mechanics. Einstein, despite his own experience in having his theories mocked, couldn’t quite embrace the idea of uncertainty and probability governing the micro world, or the concept that interaction affects things. They did eventually come to peace with each other after a fashion. 


For years, their dialogue continued by way of lectures, letters, articles. During the course of the exchange both great men needed to backtrack, to change their thinking. Einstein had to admit that there was actually no contradiction within the new ideas. Bohr had to recognize that things were not as simple and clear as he’d initially thought. Einstein did not want to relent on what was for him the key issue: that there was an objective reality independent of whoever interacts with whatever. Bohr would not relent on the validity of the profoundly new way in which the real was conceptualized by the new theory. 


Rovelli notes that even now, we have the same impasse. Quantum Mechanics is indeed weird, and often counter-intuitive. But it very clearly works to explain the world - we wouldn’t have nuclear anything without it. Rovelli’s own theory (and he is a renowned theoretical physicist) is that “reality” is only interaction. It is the interaction of matter-energy and spacetime that make up reality. As he puts it in a later chapter:


There is no longer space that “contains” the world, and there is no longer time “in which” events occur. There are only elementary processes wherein quanta of space and matter continually interact with one another. The illusion of space and time that continues around us is a blurred vision of this swarming of elementary processes, just as a calm, clear Alpine lake consists in reality of a rapid dance of myriads of minuscule water molecules. 


There is also an amazing passage that speaks to the science denialism and rejection of expertise that plagues our country in the time of Trumpism. 


But many times in the past we have realized that it is our immediate intuitions that are imprecise: if we had kept to these we would still believe that Earth is flat and that it is orbited by the sun. Our intuitions have developed on the basis of our limited experience. When we look a little further ahead, we discover that the world is not as it appears to us: Earth is round, and in Cape Town their feet are up and their heads are down. To trust immediate intuitions rather than collective examination that is rational, careful, and intelligent is not wisdom: it is the presumption of an old man who refuses to believe that the great world outside his village is any different from the one that he has always known. 


Our understanding of the world has changed immensely in the last century, as has our understanding of many other things. This same refusal to believe in a reality outside of one’s immediate experience and intuition also plagues our politics. 


I also love a passage near the end of the book, where Rovelli looks at the nature of humanity in light of our understanding of science. 


I am, as Spinoza maintained, my body and what happens in my brain and heart, with their immense, and, for me, inextricable complexity. 

The scientific picture of the world that I have related in these pages is not, then, at odds with our sense of ourselves. It is not at odds with our thinking in moral and psychological terms, or with our emotions and feelings. The world is complex, and we capture it with different languages, each appropriate to the process that we are describing. Every complex process can be addressed and understood in different languages and at different levels. These diverse languages intersect, intertwine, and reciprocally enhance one another, like the processes themselves. The study of our psychology becomes more sophisticated through our understanding of the biochemistry of the brain. The study of theoretical physics is nourished by the passions and emotions that animate our lives. 

Our moral values, our emotions, our loves are no less real for being part of nature, for being shared with the animal world, or for being determined by the evolution that our species has undergone over millions of years. Rather, they are more valuable as a result of this: they are real. They are the complex reality of which we are made. Our reality is tears and laughter, gratitude and altruism, loyalty and betrayal, the past that haunts us and serenity. Our reality is made up of our societies, of the emotion inspired by music, of the rich intertwined networks of the common knowledge that we have constructed together. All of this is part of the self-same “nature” that we are describing. We are an integral part of nature; we are nature, in one of its innumerable and infinitely variable expressions. This is what we have learned from our ever-increasing knowledge of the things of this world. 


Definitely bonus points for mentioning Spinoza. And also, this is such a great example of my experience that one need not believe in a specific version of God (or any version at all) in order to experience wonder and humanity. Indeed, all too often, it is those who loudly assert that to abandon their specific view God is to lose wonder, that seem to have the least of it. Enns is correct that our vastly altered view of the cosmos must inevitably lead to a reconsideration of our theology. In this instance, Rovelli too recognizes that, and it fills him with wonder. As it does Enns. And as it does me. 


I believe I will be recommending this book to people in the future. I am also glad that my kids get to read this stuff when they are young. My hope is that science will never be a source of fear and distrust for them, and that they will always be filled with wonder at this universe we are part of. 


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