Questions tagged [cosmology]

Questions about the origin, history, evolution and fate of the Universe.

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Could the Sun's planetary nebula be dangerous for the planets?

Since the Sun's mass isn't high enough it won't go supernova being a red giant but instead release a planetary nebula. So that seems to be kind of a substitute for a supernova. Would ejecting the ...
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1answer
99 views

Fundamental axioms in LCDM

What are the axioms (if any) behind the LCDM model of cosmology? NB: axioms, not postulates (e.g., inflation)
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1answer
173 views

Is there any other theory, apart from the Big Bang paradigm, which describes the birth of universe? [closed]

The Big Bang theory is the approved theory of the "birth" of Universe. Are there any other theories which can explain how our Universe came into existence?
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64 views

Why does the Hubble flow does not carry photons with it?

I have this naive question. We know that the expansion of the universe "takes" or "carries" the galaxies with it, separating them, but this doesn't apply to photons. My guess is ...
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2answers
294 views

Can gravity cause a Big Crunch, if the cosmological principle holds?

Say we have a closed universe that follows the cosmological principle. As a result, mass is distributed equally and, if as far as I know, gravity should have no net effect on the movements of galaxies ...
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2answers
282 views

What covers the outside of the Universe? [closed]

Is the Universe a sphere with water or ice surrounding its' confinement? Are there any theories that imply the Universe being confined within a sphere of water/ice material?
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1answer
71 views

Can we observe the Milky Way on the edge of the universe? [closed]

If you traveled outward and outward in a straight line, indefinitely and pugnaciously, you would never arrive at an outer boundary. Instead, you would come back to where you began. Hence, in the same ...
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2answers
98 views

Create an inhabited black hole

Hello I was watching one of Isaac Arthur's videos about the end of time and i just got a crazy idea Is it theoretically possible to "create" a "solar system" that would look like a supermasive black ...
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1answer
198 views

Solving Friedmann equation for specific conditions

In Friedman equation: the case k < 0, with a Universe containing only matter (pressure = 0) so that $\rho = \rho_0/ a^3$ . What is the solution a(t) in a situation where the final term of ...
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1answer
134 views

What is dark energy made of? [duplicate]

What are the fundamental constituents of Dark Energy? Can we quantize dark energy in the first place, if it is a kind of Energy?
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1answer
179 views

Could there be massive charged “rivers” in interstellar space?

Some suggest that there might be currents of charged particles moving at 0.98c in interstellar space. Since this is tainted by association with the crack “Electric Universe” cosmology, my first ...
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2answers
186 views

Is parallel universe possible [duplicate]

Does parallel universe really exists or just science fiction which ain't possible? Can we ever know?
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1answer
50 views

How do you calculate comoving distance and light's travel distance? According to the formulae below?

According to Wikipedia, Distance measures (cosmology), Comoving distance: $${\displaystyle d_{C}(z)=d_{H}\int _{0}^{z}{\frac {dz'}{E(z')}}}$$ Light-travel distance: $${\displaystyle d_{T}(z)=d_{H}\int ...
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126 views

Does space being at right angles to time imply that the expansion or contraction of each occurs in a direction opposite the other's?

The Minkowski diagrams that are employed to illustrate Special Relativity depict changes in the motion of objects through the dimensions of space as occurring within a field (that's otherwise divided ...
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5answers
1k views

Vacuum of space [closed]

Firstly I’m genuinely interesting in a working explanation for this question. It is for this reason that I am editing the question to fine tune the question. In essense the question has remained the ...
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1answer
99 views

How Essential is the Vacuum Energy to Our Present Model of the Expanding Universe? [closed]

How essential to modern cosmology is the vacuum energy concept, and what would happen to our model of the expanding universe if it were proved to be non-existent?
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61 views

Discrepancy Between Results of Cosmological Observations & the Assertions of Quantum Mechanics [closed]

Quantum mechanics requires a vacuum energy 40 orders of magnitude higher than that indicated by cosmological observations. Which side is most likely to be right,& when the truth is finally ...
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1answer
146 views

How do we know that there is no border at the end of “infinite” space? [duplicate]

It has been suggested that space and beyond is infinite, but admittedly the same hypothesis was made by virtue of the fact that it is physically impossible to prove otherwise. How do we know that ...
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2answers
104 views

Large hadron collider [closed]

Whether the collision of particle will lead to a massive WORMHOLE or if BLACKHOLE is also possible? How much I know is that it's created for einstien's E=mc^2 ,conservation of energy from mass and ...
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1answer
84 views

Is our universe a singularity?

According to the Big Bang theory our universe used to be a lot smaller in size. It actually used to be so small that in the beginning it used to be a singularity. And the universe started to expand ...
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2answers
751 views

Time dilation at the Big Bang [duplicate]

At the time the Big Bang happened the matter had enormous density. According the GR (I may be wrong here) such density dilates time. If so, could it be that the time periods just after Big Bang which ...
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1answer
120 views

Why Did The Universe Expand? [duplicate]

If all of the mass and energy in the universe was in a point smaller than the size of an electron at one time, why did it expand? Did it necessarily expand immediately on formation, or could it have ...
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2answers
2k views

Which are the most energetic events in the Universe?

That's the question. I know about gamma ray bursts, is there anything more energetic?
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1answer
239 views

can a life exist outside the universe? [closed]

can a life exist outside of universe. but we know that in our universe many galaxies have life without water and oxygen and it is possible that life exist outside the universe so help me to find the ...

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