Questions tagged [universe]
Questions regarding all of time and space and its contents.
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Universe age and cosmological time dilation throughout intergalactic space
Assuming the cosmological principle, universe has the same age and cosmological time dilation throughout intergalactic space. Why can't we use them as an indicator of synchronicity in two extremely ...
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What exactly does $k\sigma$ mean in astrophysics and cosmology?
In statistics, $\sigma$ or $1\sigma$ is the standard deviation. For the normal distribution, approximately $68\%$ of the values lie within $1\sigma$ range, $95\%$ within $2\sigma$, and $99.7\%$ within ...
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Is the total energy of the Universe not invariant?
Consider a Universe which has only one object (bigger particle). The object exploded (somehow) into two smaller particles (with some release of energy). Consider the two particles to have masses M and ...
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How can $\Omega_m<1$ indicate an infinitely expanding universe?
I was reading up about the cosmological density parameters $\Omega_m. \Omega_{rel}, \Omega_{\Lambda}$ corresponding to total matter(baryonic+dark), relativistic particle matter and dark energy. I ...
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Why does Helix Nebula look like an eye?
The infrared lights, the material clumps that radiate and the whole view resembling a celestial firework or giant eye
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What is Helix Nebula made up of?
The Helix is a planetary nebula, the glowing gaseous envelope expelled by a dying, sun-like star. Helix nebula consists of two gaseous disks, how they are formed or which material is present in it.
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Is there a granted minimum known size of the whole universe? (including the non observable part)
This Forbes article How Much Of The Unobservable Universe Will We Someday Be Able To See?
claims
The unobservable Universe, on the other hand, must be at least 23
trillion light years in diameter
Is ...
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Luminosity distance in a FRW Universe
In the following presentation:
https://www.slac.stanford.edu/econf/C0307282/lec_notes/pinto/pinto.pdf
we have the relation for the luminosity distance in a FRW universe:
\begin{aligned}
D_L & =\...
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Is the gravitational constant really constant over our Universe?
For instance, if objects are travelling at relatively high speed around 'c', is G the same value for them as for us on earth?
I believe a lot of matter is travelling fast away from other matter, so is ...
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What happens at the edge of a finite and "bounded" universe?
So far, we know only about two types of universes: Infinite and finite universes (Unbounded edition).
In an infinite universe, there is no edge. Because well, an infinite space doesn't have an edge. ...
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Light/Dark energy/Dark matter
So I have been working on my comic book project that takes place on another planet. But in my story, there will be warp gates and there will be other civs that can travel between stars. I am ...
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Is there evidence against a Universe Black Hole?
As far as I know, the critical density of our observable universe coincides with the density of a huge black hole of the same radius. It could be a BH expanding at the speed of light and growing in ...
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Was the Big Bang an event within a preexisting Universe, or did it mark the beginning of the entire Universe, beyond just the observable Universe?
Could it be that the Universe is truly infinite, and the Big Bang was merely a singular, specific event that resulted in the birth of a 'bubble,' i.e. what we perceive as 'the observable universe'? ...
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If the universe has no true center, could it have antipodes?
Some time ago, I wondered where the center of the universe could be, and the answers I found were pretty much in agreement that there was no center of the universe, as paradoxical as that might seem.
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Amount of black holes over time
Hello the number of black holes is much bigger than the number of black holes in the past right?Let $b$ be the number of black holes in the universe.Obviously $\frac{db}{dt}>0$ but what about $\...
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