The universe refers to the cosmos; all of space-time and that which exists as part of it. Alternatively, it can refer to the observable universe, which only contains the part we can see. Questions tagged with this should ask about physics at scales the size of the universe or specific properties of ...

learn more… | top users | synonyms

0
votes
0answers
28 views

Where is the origin of cosmic expansion? [duplicate]

Perhaps, a rudimentary or dumb question, but nevertheless am curious. There is the idea that space is expanding at an exponential rate. From where? If everywhere, why doesn't this rapid creation of ...
0
votes
1answer
35 views

Boltzmann brain vs random star formation [closed]

I can (sort of) understand the Boltzmann brain paradox, but I have a specific question. If the universe does turn into being a thermal equilibrium in a box, wouldn't a scenario consisting of the ...
0
votes
1answer
48 views

In an infinite universe, would there be an infinite amount of matter as well?

Or would you eventually reach a point past which there is no matter? How would an infinite amount of matter work? Would it sort of "loop back" to the beginning, or would it be entirely unique the ...
1
vote
2answers
68 views

Trouble understanding spacetime and invariant interval

First, how is the invariant interval useful? How can it help us understand things around us in the universe? Second, I know that they changed time into space or better say SPACETIME in order to ...
-3
votes
0answers
28 views

What is at the centre of the universe? [duplicate]

If the big bang theory is correct then shouldn't there be an expanding mass at the centre of the universe. A black hole or something of that nature?
-4
votes
0answers
42 views

Is matter shrinking rather than,or additionally to, the universe expanding? [duplicate]

If the universe came into existence in nothing, then shouldn't the spaces between the smallest elements of matter be filled with nothing? Then shouldn't the primarily attractive forces of the universe ...
-4
votes
0answers
41 views

Light, the carrier of information. Is this hypothesis a known phenomenon?

I am seeking clarification on a naive insight that I experienced recently. It seems plausible and may be known to most academics and practitioners in the field but I would appreciate your knowledge ...
0
votes
0answers
39 views

Can we see the past view of our galaxy while observing in the sky because of the homogeneous structure of our universe?

As a sense, we think that simple speed addition should work ($V_1+V_2$) for all references but we know today that universe does not match our this sense. We cannot exceed the speed of light in any ...
-2
votes
2answers
72 views

Universe Expanding

Quick question that I was just hoping to get some clarification on. Current theories state that the universe is expanding; with those planets farther away moving away from us at a faster rate. Is it ...
0
votes
0answers
29 views

Space expanding within atoms [duplicate]

I'm hoping that "all questions are good questions." I'm a layman enthusiastically trying to comprehend cosmology and physics, and the more I learn the more questions I have. My understanding is that ...
-1
votes
0answers
51 views

How big is the universe from the point of view of light?

In the context of General Relativity, assuming an universe that is infinite in extent (which seems to be a popular idea nowadays) how big would the universe be from the point of view of light? Would ...
-4
votes
0answers
76 views

Does absolute motion exist?

Is it possible to determine if an object is in absolute motion by putting a (massless) accelerometer on it (from the moment it came into existence), and see if a flat line is recorded? An object is ...
1
vote
0answers
35 views

Are there characteristics that distinguish our universe?

Are there any defining characteristics of our universe that could be different for other universes (or "instances of our universe") that operate under the same laws of physics? And which, if any, are ...
2
votes
1answer
62 views

Cosmic Rest Frame

Cosmic Rest Frame is defined in the paper "Adventures in Friedmann cosmology :A detailed expansion of cosmological Friedmann equations" by R Nemiroff and B Patla as the frame at a point where average ...
1
vote
0answers
37 views

Is it possible for dark energy density be decreasing? [closed]

I have an equation relating dark energy density and temperature, actually they have a linear relationship, my question is how to choose the temperature? If I choose the temperature of universe, the ...
2
votes
1answer
45 views

Can a theoretical object exist as such that its mass overcomes gravitational collapse

A daydream the other day led me to the question if "a universe filled with water (or any other substance for that matter), instead of being mostly void" could exist within the rules of our current ...
1
vote
1answer
57 views

Many questions about expanding of the space

Sorry if my grammar is a bit off. But I have few questions about space and its expansion. If space expands faster and faster all the time, will there be a time when we cannot see further than "hubble ...
3
votes
1answer
61 views

How could the universe be hyperbolic if hyperbolic space isn't symmetrical?

In the 2-D projections of the shape of the universe shown here, we see that the flat universe and the spherical universe are perfectly symmetrical, so any triangle drawn anywhere on them will be the ...
0
votes
1answer
57 views

Big Bang not really the beginning of a completely new universe? [closed]

From what I know about the origins of the universe and the big bang, it is stated that it all started from an intensely hot and dense mass. This sounds like a singularity to me, which means a black ...
1
vote
1answer
62 views

In a static bounded universe, what happens to particles that hit the edge?

Consider a flat universe. The metric tensor is $$g_{\mu\nu}=\left(\begin{array}{cccc}-1 & 0 & 0 & 0 \\ 0 & 1 & 0 & 0 \\ 0 & 0 & 1 & 0 \\ 0 & 0 & 0 & ...
6
votes
4answers
2k views

Does physics claim that every possible world has or will exist? [closed]

Has physics proven that every possible world has or will exist? Someone on-line, who actually seems fairly intelligent, but troll-ish, claims that there is good reasons for it, not from any ...
-1
votes
1answer
67 views

What is a simple explanation to the fact that the universe is expanding? [closed]

How can we prove that the expansion of the universe is actually occurring to highschool children?
1
vote
1answer
46 views

Can the curvature of the Universe be a function of time?

Apologies for the repetition here, but can our Universe experience (either physically or mathematically) non-constant curvature that is a function of time?
-7
votes
1answer
64 views

If a being was able to swallow itself, where would it go physically? [closed]

if a being was made from a special type of material that allowed it to stretch and was very flexible, if it were to swallow itself, where wold it go. I mean the physical aspects of it since it wont be ...
0
votes
1answer
40 views

One particle infinite manifestation universe [closed]

I know how non-intuitive everything related to quantum physics is and I was thinking on some very unintuitive things like John Wheeler one electron universe theory ...
1
vote
0answers
32 views

Curisioty about universe [duplicate]

I am a bachelor student and I have a question going round my mind about the universe. Every one says that the universe is ever expanding and it is also said that the vast possible space is also the ...
1
vote
1answer
82 views

What would happen if there was a fifth fundamental force? [closed]

Preceding this question, as a student of physics, my knowledge of theoretical physics is somewhat limited. So I came across this article, which posited what the universe would be like if three ...
1
vote
3answers
68 views

What evidence is there that universe will not shrink again?

There are theory that universe eternally expanding and shrinking, so that every event and our lives will repeated again. At the other hand some scientists thinks that it will not shrink again because ...
-1
votes
1answer
55 views

Equation for everything?

Suppose, I throw a ball and it bounce. If we observe it from the time of it hitting the ground, we can see it moves due to the initial velocity it had and the interaction it had with the ground. We ...
5
votes
1answer
52 views

Did our Universe experience a curvature dominated phase?

So, my question is simple: did our Universe experience a curvature dominated phase? Or, rather, could our Universe have experienced a curvature dominated phase? This seems quite shruggish, at first ...
-4
votes
1answer
37 views

Put energy into void [closed]

what happens when you drop matter or energy of any type into the void , by void I mean a space of absolute emptiness with nothing more than darkness and total absence of every kind of energy , ...
1
vote
1answer
65 views

Rotational relativity? Is there an universal frame of reference for rotation?

So, there is obviously no such thing as an universal frame of reference for velocity. According to the relativity theory, there is no difference between two observers moving with respect to each ...
11
votes
1answer
2k views

Is the question: 'Is our universe the inside of a black hole?' meaningful? [duplicate]

By meaningful I mean experimentally falsifiable.
1
vote
0answers
26 views

How is it possible to have such massive black holes? [duplicate]

Recent observations discovered really massive black holes, up to $20-40$ billions Solar masses. Now, according to an recent study and various computer simulations (I'm sorry, I don't have any ...
0
votes
1answer
54 views

Rate of change of temperature of the Universe

Temperature of the whole universe is about 2.7K base on the wmap satellite. I know that temperature has to decrease to time and I have difficult time finding references for rate of change of ...
1
vote
1answer
52 views

Expanding space and red shift

Assuming space is really expanding - Due to expanding space, distant galaxies are supposed to be moving away from us. When light leaves a distant galaxy, it's wavelength is red shifted to begin with ...
-4
votes
1answer
68 views

Creating something from nothing [closed]

Space is NOT NOTHING this is space in Cantorial Set Theory: S = {(x, y, z) | r² = x² + y² + z² } But NOTHING in set theory has a special symbol and it is written like this: Ø = { ...
2
votes
1answer
77 views

Why can't our expanding universe be an imploding universe that appears expanding relative to us? [closed]

Galaxies moving away from us is our proof of an expanding universe. However, if the universe was contracting towards a black hole we would see a galaxy ahead of us accelerating faster towards that ...
1
vote
1answer
60 views

What are the pieces of evidence that universe is expanding? [duplicate]

Do we have any other evidence other than red shift? Is anyone trying to disapprove inflation? Also, can red shift occur because of large distance, not only because two objects are going farther from ...
0
votes
1answer
72 views

What happens to spacetime in a universe with no clocks?

For example, in the far future when all matter has been absorbed into BHs which have evaporated leaving only photons.
5
votes
1answer
73 views

Does the Universe spin? [duplicate]

Maybe it's a stupid question, so I will delete it if it will receive too many down votes but.. I was wondering about the Universe, and the fact that We know it's expanding; We don't know if it has ...
-1
votes
1answer
69 views

Wouldn't it take an infinite amount of time to create an infinite universe? [duplicate]

I have heard many people say that the universe is possible infinite. But, if it takes time and energy to create bodies such as planets and stars and the universe has only existed for 13.7 billion ...
-2
votes
1answer
31 views

Is it possible to detect strong light rays before they hit us? Can those light rays be strong enough to wipe out life on earth? [closed]

Our observable universe is continually expanding, so as soon as a powerful source of light is within our horizon, it should be visible from earth. I know that light weakens with distance but Would ...
3
votes
1answer
56 views

Is the cosmological horizon expanding faster than space itself?

I read that the rate of expansion of the universe is still a mystery. But if it's actually decelerating, wouldn't it mean that our cosmological horizon is expanding faster than space, and that one day ...
-2
votes
1answer
41 views

Does our Universe reside in the smallest particle? [closed]

I do not know where to ask this question in the first place, but I think here would be a start. Is there a possibility that if we go inside the smallest particle (which we have not discovered yet; ...
0
votes
0answers
26 views

What would happen if another big bang occurred at the centre of the current universe? [duplicate]

If another Big Bang occurred now, at the centre of our universe, what would happen? As the rate of expansion is increasing, the two "layers" (if there were any) would never meet, in which case, would ...
0
votes
0answers
60 views

Scale factor of the universe

Do we impose that the scale factor $a(t)$ of the Universe is a continuous function? Or there is a physical meaning? Usually in physics we define functions to be continuous, such as the velocity of a ...
0
votes
2answers
79 views

How is the universe flat?

I have real trouble visualising what is meant by the descriptor 'flat' when referred to the shape of the observable universe. Which one of the below is more accurate? a) It is flat in a 2D way, like ...
1
vote
0answers
19 views

Rate of expansion of universe during big bang [duplicate]

We say big bang was the explosion not in the space but of the space itself that took place in a fraction of seconds. Speaking practically, we say the universe has no edge and is infinite. If the ...
4
votes
5answers
172 views

Is the universe bounded?

As I understand it nobody can pinpoint an objective "center" of the universe nor "where" the Big Bang happened. It seems the observable universe is limited by our event horizon at some 14 billion ...