[tsimionescu]

It is correct, and you're also right that two rockets tethered to each other would not feel acceleration. The acceleration we feel in Earth's gravitational field is affecting our speed, though - it's slowing down the speed at which we move towards the future.

[JumpCrisscross]

> you're also right that two rockets tethered to each other would not feel acceleration

I just realized that the energy of the exhaust would warp local spacetime. So one might feel acceleration depending on how that geometry settles.