Sean Carroll

Hello, everyone, and welcome to the Mindscape podcast.

I'm your host, Sean Carroll.

In physics, which is a very broad field, includes, you know, atomic physics, plasma physics, condensed matter physics, biophysics, particle physics, gravity, cosmology, all these things.

Different fields, of course, have different rates of progress, both because of theoretical ideas and experimental input.

If you focus just on fundamental physics, and let's not argue about what that means or should mean, I take it to mean figuring out the most fundamental laws of nature the best we can.

So not including things like biophysics and condensed matter physics, not because they're not important, it's just a different thing.

I once tried to get...

the field to change the name fundamental physics to the name elementary physics the most elementary laws of physics being the idea but no one agreed with that that's okay fundamental physics is here to stay in this subfield of fundamental physics which includes sort of particle physics and gravity things like that

There haven't been a lot of helpful, experimental, surprising discoveries in the past several decades, arguably since the 1970s.

There have been a few here and there, masses of neutrinos, things like that.

Also things that we expected, like the Higgs boson, gravitational waves.

But in terms of true surprises, it's been few and far between.

That makes it hard to make progress in fundamental physics because experiments are what drive us to great ideas.

And there's one, of course, shining counterexample to this idea that there haven't been many surprises, which is the acceleration of the universe.

Back in 1998, we were told by results from two competing astrophysics groups looking at type 1a supernovae, using them to measure the expansion rate of the universe and how it changed over time, that against all expectations, the universe is actually accelerating, not decelerating in its expansion rate.

And of course, this was a big deal.

Nobel Prizes were handed out and the whole bit.

We still don't understand with complete confidence what is going on with the acceleration of the universe, which is great for fundamental physicists such as myself, for theorists who are trying to figure out what's going on.

It would be nice if we had more than that one fact, the acceleration of the universe.

It would be helpful to our project of inventing theoretical models to explain it.