Lex Fridman: evaluation

Transcript context

…The short answer is the worlds don’t exist in space. Space exists separately in each world. The following is a conversation with Sean Carroll. His third time in this podcast. He is a theoretical physicist at Johns Hopkins, host of the Mindscape Podcast that I personally love and highly recommend, and author of many books, including the most recent book series called The Biggest Ideas in the Universe. The first book of which is titled Space, Time, and Motion. It’s on the topic of general relativity. The second coming out on May 14th, you should definitely pre-order it, it’s titled the Quanta and Fields. That one is on the topic of quantum mechanics. Sean is a legit, active, theoretical physicist and at the same time is one of the greatest communicators of physics ever. I highly encourage you listen to his podcast, read his books, and pre-order the new book to support his work. This was, as always, a big honor and a pleasure for me. This is Lex Fridman Podcast. To support it, please check out our sponsors in the description. Now, dear friends here’s Sean Carroll. In book one of the series, The Biggest Ideas in the Universe called Space, Time, Motion, you take on classical mechanics, general relativity by taking on the main equation of general relativity and making it accessibly easy to understand. Maybe at the high level, what is general relativity? What’s a good way to start to try to explain it? Probably the best way to start to try to explain it is special relativity, which came first, 1905. It was the culmination of many decades of people putting things together. But it was Einstein in 1905. In fact, it wasn’t even Einstein. I should give more credit to Minkowski in 1907. Einstein in 1905 figured out that you could get rid of the ether, the idea of a rest frame for the universe and all the equations of physics would make sense with the speed of light being a maximum. But then it was Minkowski who used to be Einstein’s professor in 1907 who realized the most elegant way of thinking about this idea of Einstein’s was to blend space and time together into spacetime to really imagine that there is no hard and fast division of the four-dimensional world in which we live into space and time separately. Einstein was at first dismissive of this. He thought it was just like, “Oh, the mathematicians or over-formalizing again.” But then he later realized that if spacetime is a thing, it can have properties and in particular it can have a geometry. It can be curved from place to place. That was what let him solve the problem of gravity. He had previously been trying to fit in what we knew about gravity from Newtonian mechanics, the inverse square law of gravity, to his new relativistic theory. It didn’t work. The final leap was to say gravity is the curvature of spacetime, and that statement is basically general relativity.…

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