How does gravity bend spacetime? | Konstatin Batygin | Big Think

KONSTANTIN BATYGIN: In our daily experience, we are used to thinking of events as being separated in space and separated in time. There's a true kind of sense of simultaneity, where two things that are separated in space happen at the same time, and we're okay with that. As it turns out, that's only an approximate view of what's really happening.

In reality, space and time are strongly intertwined things, and the union of them is called spacetime. Now, spacetime is the grid, if you will, of this world. It is the coordinate system on which everything happens. And gravity tends to bend that coordinate system.

So indeed, gravity, what we experience as falling, for example, if we jump off a little hill or something like that, that is nothing. That is just a manifestation of the fact that the spacetime continuum itself is being curved by the gravitational field of the Earth.

What does this mean? What does this curving mean? It means that depending on how close you are to the source of gravity, time will pass at different rates. That said, biologically, you will not experience it differently one way or another. The only thing that this is useful for is if you wanted to build a time machine.

So, a time machine can never go backwards in time, but you can make a time machine that goes forward in time. Suppose you are a fan of some Netflix series and you want to watch the whole thing, and you don't want to wait for different seasons to come out one year apart. You just want to binge-watch the whole thing now.

Then, what you do is you build a planet, and then you put yourself in the center so that you are experiencing no gravitational field because you are weightless in the center of the planet. You drill a hole and then you put a TV outside of the planet, submerge the TV in the gravitational field so that time passes more rapidly for the TV, and then you watch.

So, as a biological being, you will not experience aging any differently, at least due to gravity. You will not experience aging any differently if you live on a mountain or on the surface of the Earth.