Does Earth Ever Occupy The Same Portion Of Space Twice?

[flobadob]

From what I understand the earth revolves around the sun and the sun revolves around a black hole in the middle of the galaxy. In turn, apparently the black hole in the centre of the galaxy is also moving through space.

With all this in mind does that mean that earth never actually encounters the same portion of space more than once?

[Old_Geezer]

You know of a grid system with which to measure it ?
Everything's relative.
As those in the know, know, the Earth remains still, it's the universe that moves around it.
(Around me actually. )

[mibn2cweus]

Earth's equator rotates at about 460m/s
Earth revolves around the Sun on average about 30km/s
The Sun moves through our stellar neighbourhood about 20km/s
and orbits the Milky Way at about 220km/s'
The Earth's overall motion through the universe (relative to the CMB) is about 371km/s in the direction of the constellation Leo.

So even though the night sky will appear quite familiar to us year after year, (except for the motion of planets, comets and such) for many years to come, I believe it safe to say that barring a reversal of time or a big crunch we will likely never pass this way again.

[jomifl]

I take it that's a no?

[woofgang]

well its always here......

[ToraToraTora]

No.

[flobadob]

The main reason I asked is because I was thinking about time travel. I know that it's not possible but even hypothetically speaking, if someone was to invent a time machine, they would have to make it a time and space machine, otherwise they would end up in deep space 10,000 years ago or whatever .

[Peter Pedant]

see what Jim says

My go is

yes definitely - the only system that doesnt occupy the same space twice or else it would repeat ( ish ) is a chaotic system and the earth's orbit can in no way be called chaotic ergo

[Zacs-Master]

In an expanding universe, surely nowhere can exist in the same time twice?

[Old_Geezer]

IMO it's an invalid question for the reason I mentioned.

Meanwhile, back in fantasy land, any time machine wouldn't need to be a space machine as much as needing a tie to the planet it was operated from.

[Zacs-Master]

Space time co-ordinates have been well theorised in SF for the last 100 years.