How do we compensate for acceleration?

[Stub Mandrel]

Thanks Oli, Zak.

I feel like I have been taken for a mug!

Lots of things I struggled to understand, now make a little more sense once the idea that the universe started as a point is dispensed with.

Still a bit disturbed by Wikipedia's assertion that expansion gets 'switched off' once things are gravitationally bound - that suggests gravity has a limit rather than than fading to zero at infinity, but that's getting picky...

Shouldn't be reading this at this time of day - (a) makes me want beer! ( I need to do some work.

[Michael-H]

I'm confused :s

Your planning on mapping the stars from a singular point in space (I've got this much)

So your planning on mapping from a singular point in time? (Where you lost me)

The reason I asked why is as a lot of objects in space are in orbit or moving in some direction and to completely remove this would be impossible. See Penrose–Hawking singularity theorem.

When you say acceleration is it that of the earth or of other celestial objects?

What I mean is if you were to map a 2°^2 section of sky, your trying to factor out the acceleration of the earth or the objects being mapped or do you mean the earth's rotation?

If its the earth's acceleration is it the acceleration of the earths orbit of the sun? Or is it the sun's orbit of the milky way? Perhaps both maybe you even want to factor in for the earth being pulled ever closer to the sun? Perhaps the milkyway's acceleration towards Andromeda? Or the milkyways movement in space? The ever expanding universe from the big bang? It's just a whole mess of singularity theorem. Which is always changing as not even the worlds finest minds can figure that out, from einstein to hawking.

For example the earth's travelling at 30km/s around the sun, the sun's travelling at 200km/s around the galaxy and that's speed NOT acceleration. Acceleration as such isn't really what's important but rather centripetal acceleration which is the speed of an object to maintain a circular orbit. With this we can factor out the movement with our galaxy but that's it. To go further you'd have to explore the other galaxy's in relation to our own. Knowledge I don't have and you'll need a heavy understanding of physics to do so, if its even obtainable information.

As you can see its a very complex/ impossible calculation depending on what your trying to acheive. I can't quite be bothered to do the math right now but the your going to need to have something to factor it against. I'm not even sure if this is known for any objects out side of the galaxy.

Bottom line is from theoretical point of view its very difficult to do. If your absolutely sure you want to do it go for it. I'd love to see the results you'll probably gain a physics degree and masters and doctorate in the process

However to change the subject from theoretical physics to a more common sense approach. Back to the singular point in space idea such as that if you were to hop on a shuttle, don a spacesuit jump outside and stay right there. Take some pictures in every direction/axis then yes its possible. Just been done already check out any star map all these factor the rotation of the earth.

Then again I could just be completely wrong about what you want to do in which case none of this was relevant at all

Everything has really been said but I thought I'd let everyone who hasn't seen this wonderful film have a chance to see it, and to understand the peculiar motion of galaxies. That is, if you cancel out the expansion of the universe the galaxies still have motion relative to each other that is governed by gravity. 

This is the original version, which is by far the best. Although the actual scientific results were more interesting later. If you haven't seen it, it will blow your mind. If you have seen it, it will blow your mind again.

http://irfu.cea.fr/cosmography

Then they published this paper on the local galactical super-cluster that they named Laniakea in Nature: http://www.nature.com/nature/journal/v513/n7516/full/nature13674.html

It came together with a simpler video by Nature: 

And their own, more data-heavy video: 

Using these kinds of catalogues about galaxies or stars* you can transform your position of observation to any place, time or reference of movement and view the galaxy from there. As has been said, for most intents and purposes the visible movement on human time-scales will be too small to notice or be affected by.

*) here's a nice app visualising the local galaxy based on the Hipparcos (I guess) data of about 100000 stars: http://stars.chromeexperiments.com

Michael