Wendy Freedman

So several different things to unpack in your question.

You could ask, you know, is there a concentration of mass locally so that or maybe we live in a giant bubble, say, and that... Matt lives in a bubble.

So maybe the expansion rate locally is higher because...

they were being pulled to this mass concentration.

And that was talked about a lot at the time when we were arguing about 50 and 100.

Maybe the mass distribution wasn't well mapped out.

But now there are literally thousands of supernovae that have been measured.

You can measure really well across the sky, and there's no evidence that it is varying locally from region to region.

to the percent level.

As I said, the universe does evolve with time.

And we don't know, as I said, also, we don't understand what the dark matter is yet.

We don't know what the dark energy is.

So there's lots of, I think, the tension is a tantalizing idea that maybe this is additional physics because we don't yet understand the nature of the dark energy.

But it's very interesting because

In the last decade, there have been probably 1,500 papers that have been written and posted to the Astronomical Archive that have tried to explain the Hubble tension.

And none of them has succeeded.

And the reason is, in large part, because there's so many other observations that can constrain what a model can do.

And the effect that it would have, that we would be able to measure observations

with measurements today or with the microwave background or so on and so on.

So this is where we are at the forefront.