Adam Brown

Or even closer to home, the center of the sun.

It's not clear exactly whether we can get intelligent life living at the center of the sun, even though it has the same laws of physics as us.

It just has different environmental variables.

We have, in the 2000s and before, very carefully studied the cosmic microwave background, what's sometimes called the echo of the Big Bang and the inhomogeneities in it, the fact that it's not quite the same in every direction.

And doing that, discovered a super interesting fact that was definitely not known in my lifetime anyway, which is the quantum origin of all of the structure we see in the universe.

So if you look out in the universe,

the density is not the same everywhere.

You know, the density on Earth is much more than an interplanetary space, which is itself much more than an intergalactic space.

And the sun, you know, central sun is all the more denser.

It is inhomogeneous.

It is not the same.

And if you look back to the early universe, it was considerably more homogeneous.

It was homogeneous to one part in 10 to the 5 or 10 to the 6.

Super almost everywhere, every point had almost exactly the same density.

And so then there's kind of an easy part and a hard part.

The easy part is understanding how if you have...

very small inhomogeneities, how they grow into large inhomogeneities.

That's already quite well understood by classical physics.

Basically, the idea is this.

If you have a place that's denser and a place that's less dense, then the gravitational force pulls stuff