Masteria Expansions, Names and the proof for each

Actually, it isn't gravity that keeps us from being left behind in space as the earth rotates... it's momentum.

So if, as Afrobean said, the time traveling matter is affected by forces, then it would continue being affected by its circular momentum around the sun and etc.

Then again, the fact that you're going backward complicates things. If you were standing on a particular brick in Helios Tower, and you rewind back to when Helios was being built, you'd be carried back to wherever that brick came from.

Wouldn't it be inertia that keeps us on the earth? We would certainly have momentum from the earth, but isn't it the whole 'object in motion stays in motion' idea that explains it. I'm not really too sure on that...

But I just assumed that whatever device you used to travel though time would have some sort of inertia/momentum canceling device should you want to stay in the same physical spot you started in (in a different time), otherwise you would have to be in a different spot. I guess it would have to be built to move things in the 3ed dimension, which I would find to be infinitely more practical that staying in the same spot.