What Is Real? by Adam Becker
In Quantum Mechanics, there are two worlds. One is the 'real' world which you and I understand and observe and can discuss - where a ball is, how fast it moves, etc. The other is 'quantum' and is the world of the very small - atoms, electrons, etc.
Quantum Mechanics is essentially a set of mathematics that physicists use to determine what will happen. They set up an experiment, execute it, and they get certain results. Quantum Mechanics is the math that tells them what those results will be.
According to the 'Copenhagen Interpretation' of Quatum mechanics, this 'quantum' world is not real, and the math tells you what will happen in the real world, but does not tell you anything about the quantum world itself. According to [the] Copenhagen [Interpretation], the fundamental nature of reality is not to be understood. TLDR; Copenhagen says: "Shut up and calculate" - the math works, regardless what the nature of reality actually is.
There are various other interpretations of Quantum Mechanics, and there is a long history of disagreement within the physics community around this realm of interpretation. All the physicists agree that the math works, but disagree about what the math means about the nature of reality itself.
The funny thing about Quantum Math is that they can't actually predict what any one photon or electron (or other subatomic particle) will actually do. The math says: When you take a measurement, there is a 20% chance the photon will be in THIS POSITION, a 20% chance it'll be in THAT position, etc etc. But the math can't definitely say which of those positions the one photon will be in. If you shoot out 10 million photos, then 20% of all the photons shot out will be in THIS position, 20% in THAT position. So the Quantum Math can tell you the statistical distribution of what subatomic particles will do, but can't tell you what one specific particle will do.
It's furkin weird. Classical physics doesn't work this way. If you throw a ball with X power in Y direction, the math can tell you exactly where the ball is going to go. If you throw a million balls this way, they'll all follow the exact same trajectory (at least if we ignore outside forces like wind). But the subatomic particles just don't work this way, and it's because they act like waves. The wavy nature of subatomic particles causes this strangeness, but I'm not going to dive into that in any detail here. You can read the book if you care. It's fucking excellent.
So anyway, one of the other interpretations of Quantum Mechanics is the "Many Worlds Interpretation". Like I said before, the one single photon has a 20% chance of going HERE, a 20% chance of going THERE, etc. WELL, in [the] Many Worlds [Interpretation], the photon goes both places, and in doing so creates alternate realities, alternate universes. There is a universe where the photon goes HERE, and there is a universe where the photon goes THERE. It turns out, the human observer, only descends into one of these universes (and there is another human observer who descends into the other universes).
There are other valued theories as well that challenge the Copenhagen interpretation.
One of the wildest things about Quantum Mechanics is non-locality - the fact that some things happen faster than the speed of light. This violates Einstein's theories of Relativity, which says NOTHING can go faster than the speed of light. This has been validated experimentally too. Though, depending on your interpretation, you might be able to argue that speed-of-light (locality) is respected. I believe Many Worlds keeps locality in tact.
Another wild thing is - the subatomic "particles" might not be particles at all. The (I think) popular conception of an electron is that it's a tiny little ball, even if it acts like a wave sometimes. But there might not be any actual "particles" at all. I think this is still an open question. But either way, the math works!
The exploration of the physics itself is incredibly interesting to me, and is the main reason I checked out this book from the library. It's one of the best written books I've ever read, and it's on a topic that is just SO INTERESTING to me.
But what surprised me about this book is the HISTORY. It is primarily centered from about 1900 to about 2000. Not much seems to change from 1980 - 2018 in terms of the central conflict of the book - the Copenhagen Interpretation (and unwillingness to consider other interpretations) versus other interpretations (and the desire to continue investigating the fundamental nature of reality).
One of the most interesting history lessons in here is how Nazi Germany and World War 2 influenced the development of physics.
Einstein was a Jew, and so were many other prominent physicists of the time. Before Hitler came to power, German was the primary language used within the physics community. Because of Hitler's regime, a lot of Jewish scientists were pushed out of Academia, many going to the U.S. Through all of this, English became the new standard language in the physics community.
The War also caused a fundamental change in the physics community. Before-hand, there were about 400 physicists worldwide (the book does not discuss the Eastern World, so I assume this figure regards the West). But the War led to the development of new bombs (Nuclear) and new power (Nuclear), among other developments. Funding into physics ballooned from about 7 Million a year to about 400 Million a year, and the research in Physics became much more singularly focused on practical applications.
The philosophy of physics, before the war, was an incredibly prominent feature within the Physics community - the debates about the interpretations I discussed above. But the University curriculum changed with the new focus on pragmatism, and the philosophy side was lost. Textbooks started teaching the Copenhagen interpretation as if it was the one true philosophy, and other interpretations were almost entirely ignored. This is apparently still an issue in the most recent decade.
Also - Universities in the U.S. had "Jewish Quotas" starting around the 1920s, where Universities would only permit up to a certain number of Jewish students each year. Stanford's policy on this ended in the early 1960s.
Further, one scientist - David Bohm - presented an alternative to Copenhagen called the 'Pilot Wave Theory', which I'm not sure how to explain. But the point is, it's an alternative to Copenhagen and it was hidden for many years because of Fascism in the United States.
Bohm had spent some time in a communist group on campus. He eventually left because the group was basically pointless and didn't do anything useful. But this was during the Cold War. The House Unamerican Activities Committee (HUAC) interviewed him. He was blacklisted and so was not able to get a job at any American universities. He moved to Brazil, and the U.S. revoked his passport so he wouldn't be able to travel to Europe for physics conferences and such.
He did write a paper about Pilot Wave Theory and submitted it to a physics journal, but he wasn't able to go discuss and advocate for his theory due to the U.S.'s fascism. He eventually became a Brazilian citizen and was able to go to Europe with his Brazilian passport.
So yeah. The history is incredibly interesting. It's peppered in this book in a fantastic way. The story of physics is laid out so well. This is one of my all time favorite non-fiction books, and I give it a big recommend.
I have a couple ... are they complaints? notes? Whatever.
I've heard that Einstein's wife was actually responsible for a fair deal of his physics work. The book did not discuss this at all. I don't know if it's true. I'm curious.
Within physics there are Quarks. I've read a little bit about Quarks before (in a Michio Kaku book iirc), but I don't remember it well, and I was hoping this book would cover that. It didn't. I believe Quarks are a subatomic "particle".
Then there's String Theory. The book mentions String Theory but doesn't get into it. I'm curious and want to learn about it. I also had read about it from Michio Kaku, but like it was so long ago. I was a teenager and I'm 33 now.
I think there were a couple other science-theory things that I was interested in that this book didn't cover.
To be honest, these aren't really complaints. The book was about one (or two) thing(s) in particular - the history of Quantum Mechanics and the conflicts around the interpretations of Quantum Mechanics. These other topics probably didn't fit in all of that, and I'm not mad at that. They're just curiosities that were unsatisfied.
I am disappointed that this book didn't talk about the Einstein's Wife rumor. I wanted to learn if it was true, and learn some details about it. So that is a complaint. (Update: I learned that the info about Einstein's wife may have come out after this book was published.)
Anyway. This is an absolutely fantastic book. I highly recommend it, if you have any interest in science. Some of the concepts are certainly difficult to understand, but I do feel the author does a good job of communicating them. Some shit's just complicated, yaknow?