Questions tagged [universe]

Questions regarding all of time and space and its contents.

Filter by
Sorted by
Tagged with
1
vote
1answer
95 views

Did universe have finite hydrogen

According to this video stars at end of time and many others on fate of universe they all agree on one thing that stars will eventually convert all the hydrogen into heavier elements and eventually ...
3
votes
0answers
130 views

As the Universe expands, do things like planets expand also, or just the space in between?

Just what the question says. As the universe expands, and space expands, do objects like planets ever expand? Does the space INSIDE of those objects expand?
1
vote
1answer
85 views

Looking at the Expanding Universe through the lens of relativity [closed]

The basis and most observable metric for how the universe is understood to be expanding at an accelerating rate is the red shift in observable light. I am assuming it has been thought about or maybe ...
5
votes
3answers
447 views

Can two planets in an empty universe meet/be pulled together?

For this question assume that the entire universe is completely empty. The universe is not expanding or contracting, it is completely motionless since time immemorial and has never moved before. Only ...
4
votes
1answer
113 views

How can you verify the theories presented on TV shows like “How the Universe Works” is current and/or valid? [closed]

There are many TV shows such as "How the Universe Works" that explain theories about the origin of the universe such as the Big-Bang Theory. What resources can I access to verify the scientific ...
1
vote
1answer
102 views

What was the process of calculating how much darkmatter/matter/dark energy the observable universe consists of and how did it come at this conclusion

In 2015 the Planck satellite consortium released an analysis of data collected by the Planck satellite that showed this percentage break down of the universe’s mass/energy. Ordinary matter: 4.9% ...
6
votes
1answer
608 views

Can information leave the observable Universe?

From what I gather, the observable universe is expanding at the speed of light. In addition, information cannot travel faster than the speed of light. It seems as though these two facts would imply ...
2
votes
2answers
139 views

What happens for a “closed” universe without any content?

Let an universe with no content and positive curvature. Friedmann-Lemaître equation $$H^2=\frac{8\pi G}{3}\left(\rho_m+\rho_r+\rho_{\Lambda}\right)-\frac{k\, c^2}{a^2},$$ where $a$ corresponds to the ...
1
vote
1answer
72 views

Is the universe always expanding

Currently we observe that the universe is expanding. And this expansion even goes faster and faster. Why do we know (or presume) that this expansion started slowly at a singularity (i.e. big bang) ...
2
votes
2answers
121 views

How much of the Universe is subatomic? [closed]

How much does subatomic particles such as photons, tachyons, and electron being the biggest particles etc. occupy space? If put in a ball how big of a ball would that be?
2
votes
0answers
63 views

What is the total number of stars in the universe? [duplicate]

I mean a total number of stars, not the only ones that we can see.
0
votes
1answer
82 views

Why Is The Expansion of The Universe Allowed To Move Faster Than Light? [duplicate]

Why is the expansion of the universe allowed to faster than light if everything that moves within a vacuum can't reach the speed limit of light? I've read that astronomers looked at the distance ...
2
votes
2answers
248 views

What explains the existence of energy/matter if it cannot be created or destroyed?

If the energy/matter that was contained in the singularity before the Big Bang had always existed, and if it’s true that energy/matter cannot be created or destroyed, then what explains its existence?
1
vote
0answers
65 views

3-sphere universe [closed]

I have just read on this site that there is a Newtonian solution to Einstein's field equation but that it is spherically symmetrical and therefore not isotropic (having a centre for example) and so ...
0
votes
1answer
73 views

How can the universe be expanding? [duplicate]

I assume expansion implies an increase in the volume of the universe. But if the volume of the universe is increasing, does that not imply the area it is expanding into's volume is being reduced?
3
votes
0answers
99 views

Is the acceleration of the expansion of the universe a direct observation or an interpretation?

Is the acceleration of expansion we observe with supernovae direct or is this an interpretation according $\Lambda$CDM model ? I mean what we observe is luminosity distance versus redshift, so to see ...
1
vote
1answer
136 views

Is it possible that the Universe is expanding due to additional Big Bang events?

Is it theoretically possible that the Universe is expanding due to additional Big Bang events that have occurred at the same location that the original Big Bang occurred at? Perhaps there has been an ...
7
votes
3answers
2k views

When the universe expands does it create new space, matter, or something else?

I am wondering what exactly is meant when it is said the universe expands. Does it simply create new space for matter to fill, does it also create new matter/dark matter to fill that space, or am I ...
5
votes
4answers
275 views

Influences from outside the observable universe explaining dark energy and expansion?

Could some influence from outside the observable universe be causing the expansion?
58
votes
4answers
16k views

Does the Milky Way move through space?

Does our galaxy moves through space? Or does it stay in a single location? If it does move, what causes it to move?
2
votes
1answer
51 views

Where can I find source data for the graph of metric expansion over time, as shown in this ESA web page?

This web page from ESA/Hubble, shows the size of the universe over time. (I know that "size of the universe" is a gross simplification and open to multiple definitions and ambiguity, but this kind of ...
3
votes
2answers
115 views

Light beam (1 photon) in the limited universe?

If our universe is not infinite, what happens with the light beam (or photon) when it will travel through the whole universe? For example, observable universe according to wikipedia has diameter 93 ...
1
vote
2answers
151 views

Why do we presume that the universe has always expanded?

When I read about the universe having always expanded from a 'singularity', I can't help but wonder if that is perhaps not the case. If a singularity is a point at which everything is infinite and is, ...
8
votes
1answer
2k views

is there any theory or observational evidence that our universe is electrically neutral or not?

It seems our universe is neutral in large scale. There is CP violationwiki problem about matter and dark matter. Similarly is there any theory about whether our universe is electrically neutral? ...
0
votes
2answers
395 views

Does the edge of the Universe travel faster than the speed of light?

The Universe is expanding faster than the speed of light then does that mean matter at the edge of the universe is also traveling at the speed of light or are ether opposite sides of the universe are ...
23
votes
4answers
5k views

Why is the observable Universe larger than its age would suggest?

The age of the Universe is estimated at 13.8 billion years, and current theory states nothing can exceed the speed of light, which can lead to the incorrect conclusion that the universe can't have a ...
2
votes
1answer
125 views

Yet another Question about the expansion of universe

A galaxy 13 billion light-years distant is 94% of the way to the big bang. The universe was 800 million years old when the light was emitted. That galaxy today is traveling away from us at 94% of the ...
3
votes
1answer
117 views

Methodology for size of Universe

I understand that the Universe could be either finite or infinite and that it is, at the least, "very large". :) My question is, why doesn't the math involved in making the CMB and other predictions, ...
4
votes
1answer
166 views

How can heavy elements exist when the universe is young compared to the lifetime of a star? [duplicate]

Our sun is said to be incapable of producing heavier elements, and these are thought to originate from older stars dying and going supernova. If our sun is 4-5 billion years old, and has a lifetime of ...
43
votes
8answers
5k views

What is in the center of the universe?

If the universe has formed & originated by a Big Bang Explosion, then there must be empty space left in the center of the explosion site, as all the matter is travelling at tremendous speeds away ...
2
votes
2answers
2k views

Will a black hole swallow the universe?

If black holes swallow stuff, will a big black hole eventually swallow the universe? The universe will eventually go dark, because there will not be enough matter to make stars, and all that will be ...
2
votes
1answer
2k views

If an object with mass were to somehow go the speed of light, would it destroy the whole universe? [closed]

Would an object with mass traveling the speed of light destroy the whole universe because it would have infinite energy / mass? According to wikipedia and other sources, it takes infinite energy to ...
8
votes
1answer
161 views

Does the CMB pattern evolve in a human lifetime?

I was thinking, as CMB is a snapshot of a slice of the Universe during recombination, how much the cmb is changing with time ? I mean as we progress in time we look a CMB a bit more faraway each time, ...
1
vote
1answer
115 views

Question on Friedman equation involving cosmological constant

This is the question: By considering both the Friedmann and acceleration equations, and assuming a pressureless Universe, demonstrate that in order to have a static Universe we must have a closed ...
2
votes
0answers
72 views

How to derive the equation for the age of a flat universe with a positive cosmological term?

Can anyone show the steps involved in deriving this equation from the friedmann equation with the cosmological constant involved
3
votes
3answers
115 views

Account for radiation energy in the statement “total energy of universe is zero”

I've read in Hawking's book The Theory of Everything that total energy of the Universe is zero. He explained this by saying that if there are two bodies separated by a distance and having some mass, ...
3
votes
1answer
643 views

Latest cosmological parameters

I'm looking for the latest values (with uncertainties) of the four main cosmological density parameters $\Omega_i$ : \begin{align}\tag{1} \Omega_{\text{mat}} &={} ?, &\Omega_{\text{rad}} &=...
4
votes
3answers
2k views

Are black holes expanding?

We know that it is a commonly heard claim that in every black hole there is a universe. It is also believed that the universe is expanding. If we use both of these, can we conclude that every black ...
0
votes
1answer
78 views

SETI search for extraterrestrial life [closed]

In all these years of listening, why hasn't SETI detected anything ? Is there no intelligent life out there or is it too far away to detect ?
23
votes
3answers
7k views

What would happen to a polished marble statue left in space for a million years?

Consider it doesn't collide with any other objects. Would it be preserved perfectly in the vacuum or would its surface be damaged by anything like UV rays, radiation, gas, space dust, etc?
0
votes
1answer
62 views

Is the Cosmos a super set of the Universe and any hypothetical multiverse(s)? [closed]

I'm quite lost on the definitions of words like omniverse, megaverse, multiverse, meta-universe, universe, and cosmos. I used to think the Universe and the Cosmos were essentially the same things, but ...
18
votes
9answers
2k views

Is there any practical use for astronomy?

Although astronomy is very cool and the things we are learning are awesome, is there really any practical use to knowing the things we know about the universe? Do other fields of science draw from ...
0
votes
1answer
101 views

what happens when we keep going radially away from earth?

Is the generally accepted belief in the science community, that if one sits in a spaceship and move away from Earth where r (distance between earth and my ship) is continuously increasing, can one ...
4
votes
1answer
270 views

Use of type-I a supernovae as standard candle

Why only type -Ia supernovae are used as standard candle to calculate age of universe and why not type II, type Ib, type 1c ?
1
vote
2answers
3k views

Does every object in the Universe have gravity? Space has no gravity, why?

My science teacher told me that every object in Universe has gravity but space is a part of Universe too, so, why does the space have no gravity?
2
votes
2answers
87 views

What happens if one day aliens want to talk to us. How can we talk to them? [closed]

Always I wonder about that if some day alien wants to talk to us, then how can we talk to them? They didn't know any of the language on the Earth. What will be the basic building blocks for it?
2
votes
1answer
211 views

If the Universe is Flat, why does it look 3D from our View?

So I know that the universe is flat in a 4D point of view, but what about a 3D point of view? The universe does not SEEM flat from our view, so how can it really be so? Please answer more simple, im ...
-2
votes
2answers
147 views

Is there any way to tell which way is the next universe? [closed]

Is there a observable void outside our universe that can give a clue on how far the next on is? How many universes can surround ours? What does a universes gravity well look like?
3
votes
2answers
65 views

How to fix a Direction in the context of universe? [duplicate]

My question is regarding the direction/orientation of earth. Is it a constant with reference to universal parameters?
-1
votes
1answer
84 views

Can the shedding of radiation of stars contribute to the red-shift of the universe?

The sun is losing mass(1.5cm per year) by emitting radiation and the orbits of the planets are widening because of the weakening gravity of the sun. Are most of the stars shedding mass via ...