Wendy Freedman

And then WMAP, the Wilkinson Microwave Anisotropy Probe,

first measurements of all sky in space for the microwave background got a value of 71.

So it looked pretty good.

And the acceleration of the universe had been discovered.

The age was something like 13.7 or 13.8 billion years.

And wow, here you are measuring locally using stars and you're using

The redshift of 1100, 380,000 years after the Big Bang, you're making these tiny measurements of the temperature differences.

And boy, they agree pretty well.

That is a measurement of how fast the universe is expanding at the current time.

It has units of inverse time.

So it is also a way of getting at the age of the universe.

in detail is kilometers per second per megaparsec.

So when we talk about a Hubble constant of 70, we mean 70 kilometers per second per megaparsec.

Yes.

Exactly.

That was Edwin Hubble's original discovery.

What he showed is the farther away a galaxy is, the faster it's moving away from us.

The slope of that correlation is the Hubble constant.

That is the expansion rate at time t equals zero, now.

We could be missing things.