Stephen Wolfram

But that didn't work out technically because it wasn't consistent with relativity theory.

It didn't seem to be.

And so then in the history of physics, even though people had determined that matter was discrete, electromagnetic field was discrete, space...

was a holdout of not being discrete.

And in fact, Einstein, 1916, has this nice letter he wrote where he says, in the end, it will turn out space is discrete, but we don't have the mathematical tools necessary to figure out how that works yet.

And so, you know, I think it's kind of cool that 100 years later we do.

Yes, for you, you're pretty sure that at every layer of reality, it's discrete.

Right, and that space is discrete.

In fact, one of the things I realized recently is this kind of theory of heat, that heat is really this continuous fluid.

It's kind of like the caloric theory of heat, which turns out to be completely wrong because actually heat is the motion of discrete molecules.

Unless you know there are discrete molecules, it's hard to understand what heat could possibly be.

Well, you know, I think space is discrete.

And the question is kind of what's the analog of the mistake that was made with caloric in the case of space?

And so my current guess is that dark matter is, as my little sort of aphorism of the last few months has been, you know, dark matter is the caloric of our time.

That is, it will turn out that dark matter is a feature of space.

and it is not a bunch of particles.

At the time when people were talking about heat, they knew about fluids, and they said, well, heat must just be another kind of fluid, because that's what they knew about.

But now people know about particles, and so they say, well, what's dark matter?

It just must be particles.

So what could dark matter be as a feature of space?