Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens | Lex Fridman Podcast #428

    General Relativity

    General Relativity is a theory of gravitation that Einstein developed in the early 20th century.


    Gravitational Redshift

    Gravitational Redshift is a phenomenon where light is shifted towards the red end of the spectrum due to strong gravitational forces.


    Black Holes

    Black Holes are regions of spacetime where the gravitational pull is so strong that nothing, not even light, can escape.


    Black Holes

    A black hole is a region in space where the gravitational pull is so strong that nothing, including light, can escape.


    Hawking Radiation

    Hawking radiation is a theory that suggests black holes emit radiation due to quantum effects.


    The Holographic Principle

    The holographic principle is a concept in theoretical physics that suggests the information contained in a region of space can be encoded on the surface of that region.


    Information in Black Holes

    Black holes are described by the holographic principle, which states that the information contained in a black hole is encoded on its surface, known as the event horizon. This is in contrast to the volume inside the black hole.


    Black Holes and the Second Law of Thermodynamics

    The second law of thermodynamics states that the total entropy of an isolated system always increases over time. However, for black holes, the entropy appears to decrease as they evaporate.


    Multiple Universes

    The idea that our universe is not the only one and there could be infinite universes.


    Quantum Mechanics and Black Holes

    Quantum mechanics suggests that particles can be created and destroyed at the event horizon of a black hole. This raises questions about the consistency of the laws of physics in different regions of spacetime.


    Holographic Principle and Quantum Field Theory

    The holographic principle and quantum field theory are two different approaches to describing the behavior of black holes. The holographic principle suggests a more simplistic description of black hole behavior, while quantum field theory is more detailed.


    The Current State of Dark Matter and Dark Energy

    Dark matter is just a particle that's the most boring thing in the world and it's uh non-uniformly distributed through space Dark Matter absolutely yeah so this you can even see maps of it that we've constructed from gravitational lensing so verifiable sort of clumps of dark matter in the Galaxy that explains stuff bigger than the Galaxy sadly like we think that in the Galaxy dark matter is Lumpy but it's weaker it's effects are weaker but of the scale of large scale structure and clusters of galaxies and things like that yes we can show you where the dark matter is could there be a super cool explanation for dark matter that would be interesting as opposed to just another particle that sits there in clumps the super cool explanation would be modifying gravity rather than inventing a new particle sadly that doesn't really work we've tried I've tried uh that's my third paper that was very successful I tried to unify dark matter and dark energy together that was my idea that was my aspiration not even idea I tried to do it it failed even before we wrote the paper I realized that my idea did not help it helps it could possibly explain Away the Dark Energy but it would not explain Away the Dark Matter and so I thought it was not that interesting actually and then two different collaborators of mine said has anyone thought of this idea like they thought of exactly the same idea completely independently of me I said well if three different people found the same idea maybe it is interesting and so we wrote the paper and yeah it was very interesting people are very interested can you describe this this paper a little bit like it just it's it's fascinating how much of a thing there is dark energy and dark matter and we don't quite understand it so what what was my dive into the exploring how to


    Quantum Mechanics

    Quantum mechanics is a harder one you know I wrote a textbook on general relativity and I started it by saying general relativity is most beautiful physical theory ever invented and I I will stand by that it is less fundamental than quantum mechanics but quantum mechanics is a little more mysterious so we it's a little bit cluggy right now you know if you think about how we teach quantum mechanics to our students the Copenhagen interpretation it's a god-awful mess like no one's going to accuse that of being very beautiful


    Many Worlds

    Many worlds just says look I just told you a minute ago that there's only one wave function for the whole universe and that means that you can't take too seriously just describing the electron you have to include everything else in the universe in particular you clearly have to interact with the electron in order to measure it so whatever is interacting with the electron should be included in the wave function that you're describing and look maybe it's just you maybe your eyeballs are able to perceive it but okay I'm going to include you in the wave function


    Quantum Mechanics

    The role of quantum mechanics in the understanding of the universe and the potential for new discoveries.


    Hilbert Space

    Hilbert space the space ball Quantum wave functions was always big enough to include all of them I'm going to worry about the parts of the Universe I can observe so let's put it this way many worlds comes about by taking the schroer equation seriously the schroer equation was was invented to fit the data to fit the spectrum of different atoms and different you know emission and absorption experiments and it's perfectly legitimate to say well okay you're taking this rodinger equation you're extrapolating it you're trusting it beyond what we can observe



    The possibility that our reality is a simulation created by a more advanced civilization.


    Limitations of AI

    The limitations of artificial intelligence and its potential to simulate human intelligence.


    Emergence of Intentionality

    The emergence of intentionality in artificial intelligence and its potential to simulate human behavior.


    AI Models and Representation of the World

    The author discusses the limitations of large language models in understanding the world, citing the example of a child playing with a toy car and creating a world in their mind. They also mention that the model's training data is based on human-made datasets, which may not accurately represent the world.


    Enterprise Computing

    The author discusses the possibility of using quantum computing to increase the scale of computation and improve the efficiency of data centers. They mention that physics can help expand the scale of compute and energy required to make computers happen.


    Emergence of Complexity

    The author discusses the emergence of complexity from simple rules and systems, using cellular automata as an example. They mention that these systems can exhibit complex behavior despite having simple rules.



    Complexity has different meanings... complexity is what you might think of as configurational complexity that's what kolmogorov gets at how much information do you need to specify the configuration of the system...


    Consciousness and Reality

    You know the birth of imagination eventually you've been noticing that right can you make the case for pansychism and against it... is panpsychism the idea that Consciousness permeates all matter it's maybe it's a fundamental force or it's the way of the fabric of the universe...


    Naturalism and Poetic Naturalism

    Naturalism is just the idea that all that exists is the natural world there's no supernatural world you can have arguments about what that means... poetic naturalism is just the idea that you shouldn't be too fundamentalist about what the natural world is...


    Morality and Meaning

    The poetic really looks at the at the uh let's say the pothead questions at the edge of science is more open to them... what we mean by Aesthetics or morality are we're attaching categories properties to things that happen in the physical world...


    The Connection between Science and Physicalism

    He faster we recognize that and deal with it the better off will be but if we deeply and fully understand the functioning of the human mind won't be able to incorporate that no that will absolutely be helpful in explaining why certain people have certain moral beliefs.


    The Complexity of Human Morality

    Science can't tell you right from wrong you need science to implement your ideas about right and wrong if you are functioning on the basis of an incorrect view of how the world works you might very well think you're doing right but actually be doing wrong.


    The Role of Curiosity in Science

    I do I do and yeah I do and yeah it's just like I everyone is you know has their foibles or whatever so I'm not able to do that therefore I have to just figure it out on the fly


    The Dance Between Humility and Strong Opinions

    I love the actual dance between humility and having a strong opinion on stuff which is a great it's a it's it's a fascinating dance to pull off


    Einstein's Equation for General Relativity

    You know Einstein's equation for general relativity and the punchline is the equation is much smarter than Albert Einstein because Albert Einstein did not know about the Big Bang he didn't know about gravitational waves he didn't know about black holes but his equation did and that's I mean that's a miraculous aspect of science more generally but general relativity is where it manifests itself in the most absolutely obvious way uh a human question


    Nobel Prize

    Einstein didn't get the Nobel Prize for general relativity tragedy he should have gotten maybe four Nobel prizes honestly um he certainly should have got the the photoelectric effect was 100 % worth the Nobel Prize because and people don't quite get this who cares about the photoelectric effect that's like this very minor effect


    Science and Nobel Prizes

    Nobel Prize has enormous problems uh I think it's probably a net good for the world because it brings attention to good science I think it's probably a net negative for science because it makes people want to win the Nobel Prize


    Sean Carroll and The Podcast

    Sean thank you for being the person that makes us um celebrate science and fall in love with all of these beautiful ideas and science for writing amazing books for being legit and still pushing forward the research science side of it and uh for allowing me and uh these pothead questions and also for educating everybody through your own podcast