If all galaxies began to show red shifts, what would this change indicate about the fate of our universe?
1 Answer
The red shift alone would only say that those galaxies are moving away from us, but would not be enough to tell us the ultimate fate.
Explanation:
To my knowledge, we do see red shifts in all galaxies, which means they are travelling away from us as the universe expands.
To gain some insight into what this might mean in the distant future, there are three scenarios generally suggested:
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The closed universe: If there is sufficient mass in the universe, the combined gravity of all this mass will eventually halt the expansion, then reverse it, leading to a collapse that physicists call the Big Crunch.
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The open universe. If the quantity of mass is far short of what is needed in the closed scenario, the universe may go on expanding forever, and the expansion will never stop.
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The flat universe. If the quantity of mass is "just right", the expansion will gradually slow, and eventually stop, just as the size of the size of the universe becomes infinite.
Most physicists believe that the flat universe scenario is the correct one, even though it implies "just the right amount" of matter exists.
So, the total amount of matter in the universe is the crucial factor.
And then, there is dark energy...
