Doesn't the universe have to be finite because of gravity?
[From: ] [author: ] [Date: 14-06-15] [Hit: ]
His general relativity equations told him that the universe could not be static based on the way gravity curved spacetime. Again, it was widely believed the universe WAS static so he introduced a constant to ensure his equations gave a static universe. He later called the introduction of that constant (for which there was no theoretical basis) the biggest mistake he made. So, the point is that whether the universe is finite or infinite does not alter the fact that it cannot be static.......
This is counter-intuitive, but then, that's why we needed to wait until the mathematics was sorted out before we could do the calculation properly.
Interestingly, Einstein also made a similar error. His general relativity equations told him that the universe could not be static based on the way gravity curved spacetime. Again, it was widely believed the universe WAS static so he introduced a constant to ensure his equations gave a static universe. He later called the introduction of that constant (for which there was no theoretical basis) the biggest mistake he made.
So, the point is that whether the universe is finite or infinite does not alter the fact that it cannot be static. Therefore, you cannot reverse the argument to draw a conclusion about the nature of the universe - you cannot tell whether the universe is finite or infinite based on the fact that gravity is attractive according to Newtonian physics. That's why you need General Relativity to describe the 'correct' nature of the universe.
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The universe is finite because its total mass-energy is zero.
Source(s):
http://universemass.blogspot.com
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No.
Even an infinite universe, with matter (and gravity) everywhere, can "resist" collapse... as long as the density of matter is low enough.
Also, because the universe is young (13.8 billion years), the gravitational "information" from each bit of mass, cannot have reached further out than 13.8 billion light-years (the size of the Observable Universe in "look-back" distance).
So, even if there is an infinite amount of mass located beyond that "horizon", it has no gravitational effect on "our" corner of the universe. And we have no effect on them.
Astrophysicists worked out a unit to measure the average mass density of the universe, and assigned the value "1" to the critical density. The measure is called Omega.
If the universe's Omega is greater than 1, it will eventually collapse onto itself due to its self-gravity.
If less than 1, expansion continues forever.
So far, measurements indicate that the actual value is... darn close to 1.
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Source(s):
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http://en.wikipedia.org/wiki/Friedmann_e...
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No, the Universe is finite and limitless. and dont forget it´s expanding.
the most recently discovers about the hubble ultra deep field shows that all the galaxies are been atracted eachother in clusters, to form a cosmic web called "Great Atractor".
http://en.wikipedia.org/wiki/Great_Attra...
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The beginning and central point is everywhere.
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No gravity in outer space. Crazy, isn't it?
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