Space expansion is a cosmological phenomenon wherein the proper distance between two spatial points for a given inertial reference frame increases from one moment of time to another. That is, space itself expands; the added distance is not due to relative motion of points or objects.

learn more… | top users | synonyms

1
vote
1answer
95 views

What is the age of universe? [closed]

As we know at the time of big bang as mentioned by the scientist the universe expanded faster than the speed of light. So does it mean that at that time all the particles present travelled in the time ...
2
votes
3answers
495 views

Why the temperature is getting lower when the universe is expanding

As we know, if an ideal gas expands in vacuum, as its energy is unchanged, the temperature remains the same. An ideal gas's energy does not depend on volume. In general, the energy is $kT$ times the ...
1
vote
0answers
53 views

Is the speed of light the ultimate speed limit? [duplicate]

As we all know nothing can go faster than the speed of light as mentioned by most of our pioneer's in physics. But as I was listening to one of the statements of Sir. Stephen Hawkins he stated that at ...
10
votes
1answer
212 views

Equation of state of cosmic strings and branes

I'm sure these are basic ideas covered in string cosmology or advanced GR, but I've done very little string theory, so I hope you will forgive some elementary questions. I'm just trying to fit some ...
2
votes
1answer
200 views

acceleration of the universe

Moments after the Big Bang, the universe was expanding at an incredible rate, (I've heard) faster than the speed of light. Due to dark energy, scientists predict the rate of expansion will pick up ...
1
vote
1answer
104 views

Redshift and shapes of galaxies

How does peculiar velocities lead to the observed elongation of galaxy clusters in redshift space, otherwise known as the Fingers of God effect? I have read the relevant Wikipedia page, but cannot ...
1
vote
1answer
176 views

Universal expansion faster than the speed of light

If the universe is expanding faster than the speed of light, and force carrier particles move at the speed of light, wouldn't this cause infinite universal expansion? Since no forces would be acting ...
0
votes
1answer
90 views

Time for Light to travel from most distant objects in universe

I understand that it is possible to detect the most distant objects in space over 13 billion light years away from us and that the universe is 13.75 billion years old. Does this imply that there were ...
11
votes
5answers
1k views

Does the amount of gravitational potential energy in the universe increase as it expands?

It seems to me that extra gravitational potential energy is created as the universe expands and the distance between massive objects such as galaxy clusters increases; this implies that energy is not ...
2
votes
2answers
2k views

Is time speeding up due to the expansion of space?

If we just look at our local galactic cluster, if all of the galaxies that are a part of it are moving away from each other, and so the overall 'density' of the strength of gravity in the cluster is ...
0
votes
1answer
110 views

How to understand movement in expanding universe?

I know that universe is expanding equally between every pair of points but it was a single point in it's very past... so I was wondering if we could locate this center point of universe. Now I know ...
1
vote
3answers
330 views

Redshift of light in dark matter

Following Edwin Hubble, it is widely believed that the universe is expanding, which is based on the red-shift of light from distant objects. Can dark matter cause light to be red-shifted and make it ...
4
votes
6answers
223 views

Why are distant galaxies not actually tiny bits of matter?

Distant galaxies are said to be moving away from the Milky Way (and us) at speeds approaching the speed of light. Since Special Relativity tells us that any object moving away from us at a velocity of ...
2
votes
3answers
572 views

If everything in the universe doubled in size overnight, would it be noticeable?

By my understanding, if everything doubled in size, such as the Sun and the Earth, and because the space in between them (which is nothing) can't expand, would the gravities greatly change and the ...
4
votes
3answers
377 views

Could metric expansion create holes, or cavities in the fabric of spacetime?

Is it possible for metric expansion to create holes, or cavities in the fabric of spacetime? According to the Schwarzschild metric, the metric expansion of space around a black hole goes to infinity ...
1
vote
0answers
49 views

What evidence is there for the Big Bang Theory? [duplicate]

Possible Duplicate: What has been proved about the big bang, and what has not? I know the expansion of the universe is the most compelling but what else makes it so well liked and believed. ...
5
votes
3answers
326 views

Is observable universe an explanation against Olbers' paradox?

First of all, let me tell you that I'm not a physicist but rather a computer scientist with a mere interest in physics at nowhere near a professional level so feel free to close this question if it ...
1
vote
1answer
163 views

Accelerating expansion of universe - entire universe a non-inertial frame of reference?

If the expansion of the universe is accelerating, doesn't that mean that the entire universe is a non-inertial frame of reference? And if so, what implications does this have (if any)?
1
vote
2answers
252 views

Cosmology questions from a novice

These ideas/questions probably represent a lack of understanding on my part, but here they are: 1) Cosmologists talk about the increasing speed of expansion of the universe and talk of dark energy as ...
0
votes
1answer
1k views

How does an inflationary universe solve the Flatness Problem, Horizon Problem and Monopole Problem? [duplicate]

Possible Duplicate: What is the evidence for Inflation of the early universe? I am reading some public science books on inflationary universe, e.g. The Inflationary Universe by A. Guth. ...
-6
votes
3answers
229 views

Could some Red and Blue shifts be the result of light passing through “dark matter”? [closed]

As i see it, light behaves in certain ways, as the Double Slit experiement shows, So when light comes into contact with dark matter, it becomes both a wave and a particle, the wave is bent around the ...
2
votes
0answers
116 views

Can decompactification explain the inflation of the early universe?

I've just reread chapter 11 of this book where it is explained among other things, that our four dimensional universe could be unstable concerning a decompactification transition, since potential ...
3
votes
2answers
485 views

How do we know the universe is expanding, and not that its contents are shrinking?

Is there a physical reason why not to think that instead of space expanding, all physical constants and parameters are shrinking (including of course the instruments we use to measure the constants) ...
0
votes
2answers
107 views

Causal reconnection

Can causally disconnected regions join up again? For example the universe is expanding faster than light creating cosmological horizon, but what if something causes the expansion to slow down and ...
0
votes
3answers
230 views

The radius of the universe and time [closed]

Ok - fair warning - Non-physicist asking dumb-assed questions here again. I've been reading a lot of Einstein, Feynmann, Ferris etc. I'm just loving this stuff. But I suddenly found myself looking at ...
0
votes
3answers
198 views

Accelerating expansion of the universe and cyclic model

So I've heard that recent observations indicated that the rate of expansion of the universe is accelerating. Does this indicate that the universe can NOT be cyclical, with an infinite series of big ...
1
vote
2answers
1k views

How can galaxies collide if everything moving outwards

If the universe started from Big Bang and everything is expanding outwards and actually accelerating away from each other, than "How is it possible for two galaxies to collide as they all are moving ...
2
votes
1answer
139 views

On non-local physics

Recently I've encountered work by prof. B.V Alekseev, in which he claims that some physical problems can be easily solved if we consider non-local interactions in kinetic theory (interactions of ...
0
votes
1answer
329 views

Space expansion looking like time dilation

Space looks like time depending on the motion of the observer so I was going to ask if space expansion was the same as the unfolding of time, but this was asked on physics.stackexchange before and the ...
1
vote
1answer
416 views

Do atoms expand with universe? [duplicate]

Possible Duplicate: Why space expansion affects matter? Why does space expansion not expand matter? As we know, the universe is expanding, galaxies are away from each other. But what ...
3
votes
5answers
425 views

How does the Hubble Redshift work?

I am a little confused about the workings of the Hubble Redshift. I do understand the classical Doppler-effect, however in special relativity the velocity of light c is a natural velocity limit. So ...
2
votes
1answer
316 views

Light coming from distant galaxies

Some of the distant galaxies appear to be receding from us faster than the speed of light due to stretch of the space between us and those galaxies. By an analogy with the ant on a rope paradox, the ...
3
votes
5answers
377 views

Space Expansion vs. Relative Motion

Inspired by a recent dialogue from another question: Given 2 objects moving at some velocity $v$ relative to one another, is it possible to determine whether they are moving or whether the space ...
1
vote
1answer
819 views

Does the large red shift value of galaxies mean they are far away?

When the red shifts of galaxies are large, why do we think that they are far away? I know about Hubble's law, Tully-Fisher relation of spiral galaxies, Faber-Jackson relation of elliptical ...
3
votes
4answers
870 views

As the universe expands, why do some things stretch but not others?

I got into watching a video on Olbers' Paradox a few days ago, and from there read about the origins of the universe, its expansion, and so on... it's always fascinated me, but now something about it ...
1
vote
2answers
127 views

Cosmological constant of standard model of cosmology and observational data

I am curious whether the current Lambda-CDM model of cosmology matches well with observational data, especially expansion of the universe. How well does Lambda-CDM defend its established status from ...
5
votes
2answers
906 views

How is dark energy consistent with conservation of mass and energy?

I initially thought that dark energy must in some way violate conservation of mass and energy since the component of the energy density of space that comes from dark energy is constant, and space is ...
1
vote
0answers
32 views

Expansion of space [duplicate]

Possible Duplicate: spacetime expansion and universe expansion? So I've heard that space is expanding very quickly and that the redshift we see when we look at other galaxies is evidence of ...
-1
votes
1answer
223 views

The expansion of space time (EST)..and the one directional flow of time?

Time flows one way...cause creates effect. Could the expansion of the universe also cause an expansion of space time in a similar fashion?...and if so, would this phenomenon explain the one way ...
3
votes
6answers
1k views

Does gravity slow the expansion of the universe?

Does gravity slow the expansion of the universe? I read through the thread http://www.physicsforums.com/showthread.php?t=322633 and I have the same question. I know that the universe is not being ...
3
votes
1answer
127 views

Does cosmic expansion imply the possibility of the universe splitting in half; multiple big-crunches?

There is an event horizon where cosmic expansion leads to superluminal recession speeds for sufficiently distant objects -- the Hubble Volume. 1) Does matter beyond the event horizon affect us ...
7
votes
2answers
354 views

Will acceleration rate of expansion of space become faster than speed of light?

From watching cosmology lectures, it seems that the space between galaxies is expanding at an accelerating rate, my question is since it is the space that is (acceleratingly expanding), the special ...
0
votes
0answers
25 views

Expansion of Universe [duplicate]

Possible Duplicate: Why space expansion affects matter? If the Expansion is prevalent, i.e. it is observable and true then shouldn't that result in the expansion of the Milky Way galaxy, ...
-3
votes
3answers
506 views

Can the big bang be “light turning into space” at the edge of the universe? [closed]

The theory I've recently come to postulates that: The volume of space filling the universe is finite and is constantly growing, thus the boundaries of the universe are constantly expanding. The ...
1
vote
1answer
474 views

spacetime expansion and universe expansion?

First of all, does the expansion of spacetime solely cause the expansion of universe? Secondly, if spacetime is the sole cause, do objects(matter with mass) themselves expand? Thirdly, by spacetime ...
0
votes
1answer
247 views

Is the FRW metric describing the shape of the universe or the shape of the expansion applied to the universe?

Is it (the output, i.e, spherical, flat, hyperbolic) describing the physical shape of the universe and its curvature at any given instance of time or is it describing the shape of the expansion ...
3
votes
1answer
295 views

Curvature, Omega, the Flatness problem, and the evolving shape of the universe

I'm a little confused by this: http://en.wikipedia.org/wiki/Flatness_problem Which seems to imply the universe is more curved now than it was soon after the Big Bang. Look at the graph on the right ...
2
votes
2answers
130 views

How to test whether galaxies are moving away from each other in a static background or whether space is being created beween them?

Observations show that galaxies are moving away from one another on the macroscopic scale. Now, scientists interpret this by saying this happens not because galaxies are really moving away from each ...
2
votes
1answer
505 views

Superluminal expansion of the early universe how is this possible?

Is this a postulate? I get the expansion of the universe, the addition of discrete bits of space time between me and a distant galaxy, until very distant parts of the universe are moving relative to ...
2
votes
1answer
421 views

How is the expansion of space itself explained in LQG?

To explain the expansion of space I have often heard people saying that space is continuously created. This picture is usually applied to cosmological scales but I`m nevertheless curious if some ...