Wednesday, August 02, 2017

Rovelli 1: Relativity and Quantum Mechanics

1. I only discovered Carlo Rovelli this last month. If you have followed my Brownian motion through science books, you will know that I have read parts of several books that have left me feeling rather empty. In the last few years I have started and not quite finished to varying degrees Tegmark's Our Mathematical Universe, Brian Greene's, The Fabric of the Cosmos, Roger Penrose's, The Road to Reality, and most recently, Lee Smolin's, Quantum Gravity. I read all but the last three chapters of Smolin's book last month, and it was he that set me on to Rovelli.

Maybe I'll go back and finish Smolin. He must decrease; Rovelli must increase.

In 2014 over spring break, I discovered The Perfect Theory: A Century of Geniuses and the Battle over General Relativity. It was fantastic. Since then I've been looking for the silver bullet to bring me up to speed on the edge of physics. I'm hoping to meet up with theology at the end. I did a MOOC that was wonderful, From the Big Bang to Dark Energy.

Since then (maybe even before then... I can't remember) I've had in mind a quasi-novel writing project called, "The First Day of Creation." I've been scrambling to read bits and pieces, trying to learn things I've been trying to learn since I was in high school. I've never gotten so far!! Schroedinger's equation is on the bucket list and is probably only a few hours of study away.

I can tell my mind is 50. I can remember how quick my mind used to be. It's depressing. I had coffee with a physics colleague of mine at IWU this week. He's just a little older than me but agreed that he could feel it.

BUT, I've never gotten this far. I've never understood so much. If only I'd have had someone to explain it to myself then!!!

2. I'm not done with Carlo Rovelli's Reality Is Not What It Seems. It came out this year. It is even better than The Perfect Theory. I don't think I've ever read anything so clear on these topics. Maybe it's just because I'm finally hitting a critical mass. I wanted to jot down notes on the first four chapters. They bring the reader up to speed with relativity and quantum mechanics.

It's so clear!! The rest of the book goes on to quantum gravity, the very edge of where physics is.

3.  I was annoyed with chapter 1. Maybe if I hadn't read so much I wouldn't have minded. He went back to Democritus and the ancient atomists. Epicurus, Lucretius. Yes, yes. Get on with it.

The nugget here was on Einstein and Brownian motion. In 1905 Einstein wrote three groundbreaking papers. One of them was on Brownian motion. It verified that matter was made up of atoms, whose vibrations knock a grain around on the surface of water.

4. Chapter two moved on to Newton in the 1600s and Faraday/Maxwell in the 1800s. Yes, yes. I've read most of this stuff before. Newton looks at space and time as the frameworks in which everything else moves. Rovelli at least likes that he subverts Plato and Aristotle. Well I do too. Half the Christian thinkers of the current age are still bemoaning that one.

Faraday and Maxwell come up with the idea of fields. You can act on things at a distance with electromagnetism. Maxwell's equations--on the bucket list and within striking distance.

5. Chapter 3. Finally. We get to relativity. I've given and continue to give some time to it. Sometime this fall I'm scheduled to do a Friday post on it. The post is already started.

One of Einstein's 1905 articles is the one where he announces special relativity to the world. Einstein solves a contradiction in the physics of his day. Normally, if you are on a train moving 40 miles an hour and throw a baseball forward at 30 miles per hour, it will seem to be going 70 miles an hour to me standing in a nearby field.

But it was discovered that the speed of light is 300,000,000 meters/second no matter where it is. If I shine a flashlight in the field, if you shine a flashlight on top of the train, if an ant on the baseball shines a light. No matter which one of us measures my, yours, the ants light speed, it will come out 300,000,000 meters per second.

Einstein's solution was brilliant. Spacetime appears to contract, depending on where you are standing. If you are moving close to the speed of light, you will seem to have shrunk and slowed down to me. And I will seem to have shrunk and slowed down to you.

6. But Einstein's general relativity has been called "the most beautiful of theories." He came out with it in 1915. I have a hunch David Hilbert really beat Einstein by a week, but as a gentleman he let Einstein take the credit. It is highly debated. Hilbert knew the math Einstein needed to finish the theory. Einstein had great difficulty getting his mind around it.

Hilbert said, "Any youngster on the streets of Goettingen understands geometry in four dimensions better than Einstein. And yet it was Einstein who completed the task" (92).

The main idea is that space curves around objects of great mass. Gravity is not a force. It is the curvature of space near a large object like the earth. So we are really simply moving along the curvature of space, not being pulled by the earth.

Rovelli goes on a fun tangent relating to Dante and the geometry of spheres. I kept telling myself. "He's Italian. Of course he's going to connect the story to its Italian connections." And, "man, this guy knows a lot more than physics." :-)

7. Chapter 4 is the best treatment of quantum mechanics I've ever read, and I've tried a number. Then again, I'm hitting a critical mass so it's bound to make more sense than ever.

Rovelli describes quantum mechanics in terms of three fundamentals. First, reality breaks down into quanta. Reality is granular. Energy breaks down into packets of photons. Matter breaks down into packets of fundamental particles like electrons, quarks, and neutrinos.

Again, I have been filling in gaps on the Standard Model these last five years. I read some in Richard Feynman. The confirmation of the Higgs boson has put the icing on the cake of the standard model. Now Rovelli can assume it.

By the way, Einstein's third paper in 1905 showed that, indeed, energy exists in quanta. Although Max Planck in 1900 is often said to be the father of quantum mechanics, he didn't really believe what he was seeing. Einstein again, showed quanta were real.

8. The second fundamental is that reality is indeterminate. This one has taken some time to convince me (Einstein was never convinced). I have disliked Heisenberg and the Copenhagen interpretation of quantum mechanics since my teens. I have a thick book by David Bohm I don't understand but hope one day to read. Like Einstein, he rejected indeterminacy.

But Rovelli has sealed the deal for me. Electrons have no positions until an event happens. This is his third point, the one I don't fully appreciate yet but am beginning to understand. Reality is a matter of events. The way he and Smolin put it is that "reality is relational." I'm sure that's better but let me start with what helps me.

"Quantum mechanics does not describe objects; it describes processes and events that are junction points between processes" (136).

The electron is only a possibility until it bumps into something. Rovelli has a great footnote where he says that Schroedinger's equation is not about reality. It only tells you the probability of where the particle will show up once an event happens. And when that happens, it is always at a point.

9. I'm not doing the chapter justice. I have known the players forever. I touched Dirac's door in Tallahassee in 1983, about a year before he died. But this chapter really moved me forward in understanding what these guys were really doing. How has this taken so long???

Heisenberg describes the appearance of electrons at a particular point as someone walking under lamp posts in the dark in Copenhagen, appearing for an instance under one only to disappear into the dark and then to mysteriously appear under another. Brilliant!

Dirac with Asperger's puts together the math, which I've realized is basically linear algebra, a new item on the bucket list. First we calculate the possible values an aspect of a particle can have ("calculation of the spectrum of a variable"). Then we calculate the probability of each possibility ("calculation of the amplitude of transition"). All those orbits we had to learn in chemistry are the possible solutions to Schroedinger's equation.

Dirac succeeds at combining quantum mechanics with special relativity. The challenge, what Rovelli is up to, is still to combine it with general relativity. That is the rest of the book.

10. Feynman also features in this chapter, connecting another strand I have not yet connected. His path to calculating the probability of a particular path is to add up all the possible paths. "It is as if the electron, in order to go from A to B, passed through all possible trajectories" (133).

11. I want to end with this chart, which is a brilliant encapsulation of the paradigm shifts that have taken place to this point in the book:

More to come...

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