[jeggers5]

It's actually quite simple.

When you throw a ball, it only slows down because of friction with the air surrounding it or because it hits something.

When you give an object force, it will just keep going because there is no opposing force to diminish the force you gave it in the first place.

Hope that makes some semblance of sense!

[ck2]

Oh I understand the physics of it and why it's harder to grasp the concept on earth with gravity and friction.

But stop and think about it - the universe is like some kind of infinite iced-over pond where something will keep going and going and going once given momentum.

I mean in space it's sliding endlessly across "nothingness" - doesn't that kinda freak you out when you really think about it?

[colkassad]

It makes sense if you accept that there is no concept of absolute rest. The state of "moving" is really the natural state...when you apply force to something, you are just changing the parameters of that state.