Physics

I have written about one of Max Tegmark’s ideas already - the Mathematical Universe Hypothesis - and in doing so I admitted he sits at the top of my favourite physicists list. That post was about a single claim. This one is about the man, and about the thing I find more interesting than any individual theory of his: the through-line. Tegmark has spent a career moving steadily inward, from measurable cosmology toward the deepest possible questions about what reality is, and the move never feels like a physicist losing the plot and drifting into metaphysics. It feels like someone following the maths until it runs out of floor. ...

In Why Is There Something Rather Than Nothing? I admitted to an instinct I have never quite been able to shake: that the laws of physics are discovered rather than invented, and that mathematics might be genuinely fundamental - not a human language we lay over reality, but part of the bedrock. I said that if we ever reach base reality, maths is the thing most likely to get us there. I left it as a feeling. This post is me taking that feeling and seeing how far a serious physicist has been willing to push it. ...

When I wrote about Yampolskiy’s Personal Universes recently, I left a thread hanging. The question underneath that whole post - the one I said I genuinely had not settled - was whether consciousness is fundamental, there first with the universe as something it experiences, or whether it is computational, something that switches on once a process gets complex enough. I said I had only recently started reading my way into the fundamental side, mostly through Donald Hoffman. This is me pulling on that thread properly. ...

“Are we living in a simulation?” is one of those questions that sounds like late-night dorm-room talk and then turns out to have a serious literature behind it. The honest short answer to “how likely” is that nobody knows, and that the question may not even have a clean numerical answer. But that is not a reason to wave it away. The reasons we cannot confidently put a number on it are themselves interesting, and they tell us something real about the limits of probability, the nature of consciousness, and what counts as science. ...

There are not many films where the visual effects pipeline produces a peer-reviewed physics paper. Christopher Nolan’s Interstellar is one of them. The visualisation of the supermassive black hole Gargantua was rigorous enough that it ended up in Classical and Quantum Gravity, co-authored by the visual effects team and Nobel laureate Kip Thorne. That single fact captures what makes the film unusual. It is, on the surface, a story about love, time, and survival. Underneath, it is a serious attempt to take Einstein’s general relativity and put it on a 70mm IMAX screen with as little fudging as Hollywood would allow. ...

When a spacecraft returns from the Moon, it strikes Earth’s atmosphere at around 25,000 miles per hour. The air in front of it compresses into a glowing plasma sheath hotter than molten lava, and the vehicle effectively becomes a fireball for several minutes. A reasonable question follows - why not just slow down first? Why not fire engines to drop down to something more manageable, like the ~17,500 mph of low Earth orbit, and skip the inferno entirely? ...

I have always had this strange gut feeling that the universe is, in some sense, new all throughout the day. Not new in the dramatic science-fiction sense, where everything resets and starts over, but new in the sense that reality seems to keep unfolding into fresh versions of itself depending on what happens next. A conversation goes one way instead of another. You decide to go out, or stay in. You send the message, or you leave it unsent. Tiny differences, and suddenly the entire shape of the day changes. ...

One of the strangest facts about reality is that there is any reality at all. Not just stars, galaxies, black holes, planets, oceans, or people. Not just matter and energy arranged in complicated ways. The deeper mystery is that there is something rather than nothing. It is such a simple question that it almost feels childish when you first ask it. But it is not childish at all. It may be the deepest question we can ask. ...

Max Tegmark Cosmologist and physicist known for his work on the mathematical universe hypothesis and multiverse theory. His research bridges the gap between quantum mechanics and cosmology, exploring the deepest questions about the nature of reality. The Case for Halting AI Development Max Tegmark joins Lex Fridman to discuss the urgent need to pause advanced AI development, exploring the existential risks of artificial intelligence and what safeguards humanity needs as we approach transformative technologies. ...