Calling c the "speed of light" completely misses the point. Rather, c is the "spacetime exchange rate": how many units of space you can exchange for one unit of time.
In actuality, everything travels at the "speed of light", just not necessarily through space alone... (1/4)
Jonathan Gorard
1,754 posts
Applied mathematician, computational physicist @Princeton
Previously @Cambridge_Uni
Making the universe computable.
Princeton, NJ
Joined November 2012
- The apparent "philosophical problems" of quantum mechanics are not unique to QM at all: they are in fact the same problems that arise whenever one attempts to construct an abstract model of reality. We can see these problems already in high school-level mechanics. (1/14)
- Much more work is needed before this is really a robust result (paper forthcoming, hopefully by the end of the year), but the initial findings are clear: Spacetime discreteness may be observationally detectable in things like quasar luminosities. (1/6)
- "Quantum mechanics is just thermodynamics in imaginary time." It sounds like a hand-wavy, quasi-philosophical statement. But with a brief dive into the relationship(s) between hyperbolic and parabolic PDEs, it becomes possible to formalize it mathematically. (1/16)
- Moths are attracted to lights because of the same mathematics that underlies twistor theory and compactification in theoretical physics: projective geometry. It all starts from a simple observation: translations are just rotations whose center is located "at infinity". (1/11)
- Replying to @getjonwithitLight is distinctive only insomuch as it (like any massless particle) experiences no time, so all of its velocity vector points in the space directions, and therefore it moves with a purely *spatial* speed of c. c is merely the conversion factor between space and time. (4/4)
- I distinctly recall a time back in 2022 when various people tried to convince me that this guy was an intellectual heavyweight.Sam Altman says we have stumbled on a new fact of nature: that intelligence is an emergent property of matter
00:00 - The Rabin-Scott theorem is one of the (philosophically) deepest mathematical results I know. When properly understood, I claim that it can't help but alter your view of reality in a fairly foundational way. Yet its typical textbook presentation obscures much of this depth. (1/8)
- Gödel's first incompleteness theorem is commonly proved by means of a diagonal argument. But, in retrospect, we can see that what Gödel was really doing was proving that Peano arithmetic is Turing-complete, and then applying an argument from computational irreducibility... (1/15)
- Energy, momentum, pressure, stress, etc. are all just different ways of quantifying the same basic thing: how our perceptions of space and time get distorted over time. And once you internalize this, it allows you to think about these concepts in a much more general way. (1/12)
- One of the curious things about von Neumann was his ability to do extremely impressive technical work while seemingly missing all the big insights. He did much work on mathematical foundations in the 20s, but completely missed the incompleteness/undefinability theorems... (1/3)As great as Einstein is, he comes no where close to the brilliance of von Neumann. It’s an error of history that he’s not the most eminent scientist.
- Replying to @getjonwithitRather, everything travels through both space *and* time, simultaneously, with a speed of c. If you're standing still, then all of your velocity is focused in the time direction (with none in the space directions), so you move through time with a speed of c. (2/4)
- In physics, one often thinks of space and time as being fundamental, pre-existing concepts, and proceeds to define everything else (energy, momentum, forces, etc.) in terms of them. But it doesn't need to be so - symplectic geometry shows us how to go the other way. (1/16)
- I use computers for mathematics so much that sometimes I opt to do a really nasty piece of tensor calculus by hand just to convince myself I've still got it. Just calculated the covariant divergence of a rank-4 tensor density correctly in one shot. Took 3 pages. I feel *alive*.

















