The universe tag has no wiki summary.
4
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2answers
243 views
Does the current acceleration of universe imply that our universe is open?
Does the current acceleration of universe imply that our universe is open?
If the universe is closed, from the Friedmann's equation, the acceleration of universe wouldn't be possible, would it be? (Of ...
2
votes
2answers
63 views
Questions about the Jeans length
I have a couple of questions about the Jeans length. Suppose the universe has a homogeneous energy density, except there's a spherical region that is overdense.
I understand that if the region is ...
1
vote
1answer
33 views
Non-isolated universe and arrow of space
Could you please help me to understand two statements in physics:
1) Universe by definition is an isolated system.
But universe expands, space pours into universe, space (vacuum) has zero-point ...
-1
votes
1answer
333 views
parallel universe- are there an infinite amount of universes?
Parallel universe: in every universe, you are presented with a different decision. Does that mean there are an infinite amount of parallel universes? I.e., if in one universe I choose to go left, I am ...
-2
votes
1answer
110 views
Finite amount of matter and space
(Please bear with me.)
If the universe included multi-universes, and black holes transferred matter between them, AND yet there was a large, but FINITE amount of matter and space, How would that ...
-3
votes
1answer
168 views
If the universe is infinite, shouldn't I already have been contacted by a time and space travelling doppelgänger?
If the universe is infinite, by virtue of chance it means that every possible configuration of matter must exist somewhere (according to this documentary).
Therefore, if we accept that the universe ...
3
votes
0answers
37 views
In the αβγ cosmology paper, how do the authors assume the integral of density over time in the early universe?
In the famous Alpher-Bethe-Gamow paper, the authors say: "it is necessary to assume the integral of $\sigma_n dt$ during the building-up period is equal to $5 \times 10^4 \frac{\text{g ...
1
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0answers
58 views
Total positive charge in the Universe
In their last homework, some of my students miscalculated a charge to be $10^{20}$ C over a squared meter and I was wondering if there was as much positive charges in the entire Universe. It would do ...
1
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0answers
49 views
Why does $H_2$ form on such a long time scale?
If we were trying to figure out the time scale for a gas-phase reaction between two hydrogen atoms in a molecular cloud (which has density $~10^4/$cm$^3$), apparently the reaction would happen on a ...
0
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0answers
46 views
Flung out of the galaxy
I watched a video by Dr. Michio Kaku, in which he states a theory about Dark Matter.
This theory says that Dark Matter could be just ordinary matter from another parallel universe, which would be ...
-1
votes
0answers
33 views
What is the wave length of the entire universe?
In quantum physics, particles are also waves. Larger particles have shorter wave lengths, and macroscopic objects have extremely short wave lengths so that the wave aspect can be ignored, and ...
