Andrew Strominger

draw the weather forecast, what the temperatures are going to be all over the country.

And I do that using one set of weather stations, and I number the weather stations.

And you have some other set of weather stations, and you...

do the same thing.

So the coordinates are the locations of the weather stations.

They're how we describe where the things are.

At the end of the day, we should draw the same map.

That is coordinate invariance.

And if we're telling somebody, we're going to tell somebody at a real physical operation, we want you to stay as dry as possible on your drive from here to California, we should give them exactly the same route.

No matter which weather stations we use or how we, you know.

It's a very trivial, it's the labeling of points is an artifact and not in the real physics.

So it turns out that that's almost true

But not quite.

There's some subtleties to it.

Yeah, there's some very delicate subtleties to that, which began to be noticed in the 50s.

It's mostly true, but when you have a spacetime with edges, it gets very tricky how you label the edges.

That gets very tricky.

And Einstein didn't have it right.

In fact, he had an earlier version of general relativity

in 1914, which he was very excited about, which was wrong.