[framecowbird]

This assumes some fixed, absolute "background" space through which the universe is moving; the idea being that you'll stay in the same position in "background" space but all of the things you care about (e.g the earth) have moved on.

Is space not relative?

[throwawaytemp27]

That makes no sense to me. One particle goes in one direction at a particular velocity and another particle goes in another direction at another velocity. They diverge over time. When you travel through time, which particle’s path do you follow through space?

I often think along the gp’s lines and would love an explanation of why it’s wrong?

[Beldin]

It all depends on your point of view (literally, frame of reference). The Earth can be considered:

- stationery (geocentric observer)

- orbiting the Sun (heliocentric observer)

- spiraling about the Sun (galaxy-centric observer)

All of these are simultaneously correct and bonkers in conjunction. Hence, you need a frame of reference if you're specifying movement.