TVI_1405 said:I was wondering, if the inflation of the universe can be compared to blowing up a baloon with, say, some ink dots on it representing matter, then, as the baloon grows in size, the ink dots should be getting bigger too since they are part of the same fabric. It does not seem to be the case in the real universe...or is it? Is it only the empty space that is expanding and what would we consider empty in this case?
TVI_1405 said:Thanks phinds, that's a very good link. However, I was thinking about the pennies glued on the balloon analogy. Pennies are extraneous to the balloon objects, i.e. not part of the balloon fabric (hence, they don't change their size during the baloon inflation). Would it mean that gravity is also somehow extraneous to the expansion as it is so effective in keeping objects together? Or would it be matter and its properties that are extraneous?
TVI_1405 said:I was also thinking, in order to stop the expansion of the universe locally (say, in one galaxy), it would require the force of gravity to be equal to that of the expansion... It also means that if hypothetically, someone was in an intergalactic space where gravity would have little effect, we would expect that person to expand rapidly in relation to the objects in the galaxy...?
Also, I am curious why would gallaxies collide if the universe is expanding? As far as I understand, it happens due to so-to-say local gravity that exists between the two gallaxies...which means the value of the local gravity should be higher than that of the universe expansion (going against the expanstion). Where could we get such a strong force from in a closed system of the universe?
Please, could anyone explain it to me? I am not a physicist but I am really curious about these things... :)
phinds said:Local clusters are gravitationally bound and some galaxies are moving towards each other locally and will eventually collide/merge
You don't seem to "get" that the force of the expansionion of the universe is STAGGERINGLY weak on local scales. MANY MANY orders of magniture weaker than gravity, to say nothing of the strong nuclear force.
TVI_1405 said:Could you define "local", please? So, the object in the intergalactic space will not expand due to the strong nuclear force?
The theory of the expansion of the universe is based on the observation that galaxies and other bodies in the universe are moving away from each other at an accelerating rate. This is thought to be caused by a force known as dark energy, which is believed to make up about 70% of the total energy in the universe.
The expansion of the universe does not directly affect matter, as it is caused by the stretching of space itself. However, this expansion can cause matter to become more spread out, leading to a decrease in the density of matter in the universe.
While matter is not expanding, the space between matter is. This means that the distance between objects in the universe is increasing, causing the overall expansion of the universe.
Yes, there is significant evidence to support the theory of the expansion of the universe. This includes observations of redshift in the light from distant galaxies, the cosmic microwave background radiation, and the distribution of galaxies in the universe.
The current understanding is that the expansion of the universe will continue indefinitely, as long as dark energy continues to drive it. However, there are some theories that suggest the expansion could potentially slow down or reverse in the distant future, depending on the amount and properties of dark energy in the universe.