Posted: Oct 06, 2011 12:28 pm
Jumbo wrote:Dudely wrote:Calilasseia wrote:Thanks to the expansion of space, if you or I stand still for a moment, and stick out our arms, then our fingertips are receding from each other
Doesn't gravity stop this? Surely as the universe expands it does not cause Earth to occupy a greater volume?
Heck, even if this is true your arms would STILL be the same distance apart so far as you could tell. If everything expanded then so too would both your arms and the meter stick used to measure the distance between them.
It works as a thought experiment (more or less) but it wouldn't actually happen would it?
In some sense the expansion and its acceleration is part of gravity. (The terms that drive the expansion are present in the General theory of Relativity which describes gravity). The scale of the effect is overwhelmed by things like the strong nuclear force, and the more conventional parts of gravity over smaller scales so galaxies and planets etc do not expand but the universe does. If the rate of the universe expanding becomes high enough though the effect may dominate even those things keeping the galaxies and planets together and the whole lot may be torn apart eventually.
The expansion of the universe is tricky to visualise because its not really a volume expanding into anything else which is what virtually all analogies imply. Its more a case of all of the bodies within the universe finding over time that the distances between them are increasing. The rate of increase getting faster over time.
I explained it that way in an earlier post so was wondering if my understanding was correct. Good to see that it is! Makes for less editing of previous posts
