[jockc]

I hate that curved space graphic. Now you have some mysterious gravity pulling both the sun and earth down. I wish someone would come up with a better example to show gravity as curved space.

[Eliezer]

But gravity isn't curved space, it's curved spacetime. Think of a graph that shows both space and time, so that it shows constant motion as a straight line (four units of space per one unit of time with the slope constant). Then acceleration is a curved line. Now curve the graph paper - not through some higher dimension, but by stretching it and compressing it in ways that change the shortest distances between two points - so that the Earth orbits the Sun in a straight line. Not a straight line in space, mind you, but a straight line in spacetime: no acceleration. After all, since no one is pushing on the Earth, it should move in a straight line, right? Got it?

[ars]

Why should it move in a straight line? If no one is pushing it, it shouldn't move at all.

That graphic is just wrong, and I also hate it.

And gravity isn't the cause of the curvature! It's the effect. The cause is energy (often in the form of mass).

[Eliezer]

> If no one is pushing it, it shouldn't move at all.

Thank you, Aristotle. Objects not being pushed on continue with constant velocity, they do not stay motionless.

[ars]

So?

Electrostatic force also causes objects to move. Just making an object move does not make gravity special.