Questions tagged [universe]

Questions regarding all of time and space and its contents.

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Is time finite or infinite? [closed]

I am not a scientist nor do I have a degree in Astrophysics, but I do like to learn new things by asking questions. With that being said, I have read that time is relative to space which began after ...
580 views

Why can we trust Hubble Time if the rate of expansion is not constant?

The age of the Universe can be estimated from taking the inverse of the Hubble constant: $t_\text{universe} = 1/H_0 =d/v.$ It seems to me this method assumes that any given galaxy has been receding ...
2k views

Why does it make sense to say the universe has no centre?

If we suppose we and everything in the universe is perfectly flat. That is, we have width and depth, but no height. And we are situated on the surface of a balloon blowing up with air and expanding "...
35 views

Location of the big bang [duplicate]

If the big bang happened everywhere (as I always read when searching for an answer to "where is the universe expanding from") then we would see galaxies moving not just in an expanding ...
1 vote
93 views

232 views

Conditions in the Early Universe

I am interested in how the large-scale properties of the Universe change over time. Does anyone know a trusted website which gives the temperature, density and radius (distance to the particle horizon)...
148 views

Will the Milky Way galaxy revolve around the Andromeda galaxy or vice versa?

As all of you know, in the Milky Way galaxy, the Solar System revolves around the Milky Way to complete the Galactic year (because we have the supper massive black hole in our Milky Way galaxy) then ...
187 views

Size of the whole universe if it were spherical

Suppose the universe is spherical and its density ratio is $\Omega \leq 1.00125$ $\Omega = 1.00125$ is approximately the maximum possible value of the density ratio according to the Planck Mission ...
6k views

How do we know we're not getting bigger?

Alright so I've been thinking a lot about how the universe expands and I've always wondered if we're getting bigger as well. Since everything would be getting larger at an equal rate (tools of ...
227 views

What is the elemental composition of the universe?

What is the current distribution of elements in the observable universe? Wikipedia lists the composition of the Milky Way, but I'm not sure how the values would change if intergalactic medium were ...
224 views

How did we measure the mass of the universe?

In an wiki article, observable universe, it was mentioned that, Mass (ordinary matter) 1.5×10^53 kg I wonder how did we measure the mass of our observable universe?
94 views

When did the first cold dark matter halos begin to originate?

I know that these dark matter halos should have been created in an early universe because during the formation of galaxies, the baryonic matter was too hot to form gravitationally self-bound objects ...
3k views

Interpretation of Hubble constant in SI units

The standard interpretation of Hubble constant $\approx 70~\text{km/s/Mpc}$ means that each mega-parsec of distance adds $70~\text{km/s}$ to a galaxy recession velocity from us (or to a space ...
630 views

Solar System formation, considering its and the universe's age

It is known that the Sun is 4.6 billion years old, and the complete Solar System is of a similar age. The class of stars to which the Sun belongs seems to be quite common. Stars of its class can live ...
217 views

Mass Content of the Hubble Sphere

How does the mass encased within the Hubble sphere/volume (both proper and comoving) change with time?
201 views

Why is time not a spatial dimension? [closed]

I am a little confused about dimensions. People say we have three spatial dimensions and one temporal dimension but I don't know how this is possible. How can there be different "types" of ...
104 views

Shape of the Universe [closed]

When an explosion takes place, the contents get scattered in every direction. So how is it, that after the "Big Bang", everything only went in one direction, to form a flat Universe?
1 vote
106 views

What is the evolutionary leap in the great filter? [closed]

This might be very unclear, but in pictures explaining the great filter, there is an evolutionary leap that the civilisation is most likely not to be able to pass through. But what is that leap? Is it ...
109 views

Time and space travel as applied to expanding space and the ratio of/between time and distance

If a place is 500 light years away, then I set out to this place, then is it true to say that, the place which I set out from, will be 750 light years away from my destination, once I have reached it? ...