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2answers
246 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 ...
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1answer
766 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. ...
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3answers
215 views

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

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
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0answers
112 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
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2answers
450 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) ...
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2answers
100 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 ...
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3answers
196 views

The radius of the universe and time

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 ...
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3answers
188 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
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2answers
970 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 ...
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1answer
130 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 ...
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1answer
267 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 ...
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1answer
332 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
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5answers
385 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
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1answer
273 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
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5answers
320 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
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1answer
695 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
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4answers
669 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 ...
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2answers
117 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 ...
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0answers
29 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 ...
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1answer
201 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
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6answers
947 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
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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 ...
6
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2answers
302 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 ...
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0answers
24 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
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3answers
462 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
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1answer
381 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
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1answer
230 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
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1answer
246 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
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2answers
129 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 ...
1
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1answer
390 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
410 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 ...
2
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1answer
303 views

how many times have the first photons lapped the universe?

I'm not really interested in the actual number of times, but rather an explanation of a closed Universe. How do we still measure the background radiation of the Big Bang? Those electromagnetic waves ...
4
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2answers
917 views

Elasticity of Space; How does the expansion of Space affect gravity?

Does space have an elastic quality? What I was thinking about was if space is expanding, is it being 'stretched', like a balloon being blown up, and if so, is this causing gravity to weaken? Imagine ...
2
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1answer
141 views

The range of light

It occurs to me that the empirical evidence shows that there is a point out in space where light stops coming from. Putting aside the expansion of the universe for a second, and focusing strictly on ...
3
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2answers
1k views

Value of the Hubble constant over time

There is something I don't understand about the Hubble "constant" H, as it seems to clump two concepts together that I can't quite unify in my head. On the one side, we have V = D * H which means ...
6
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3answers
165 views

Universe is expanding at enormous speed

I'm not an expert but I've come to understand that the universe is expanding at enormous speed. That means that all of the visible galaxies are moving away from us at great speed. I also came to ...
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2answers
128 views

Space expansion effect on wavelengths across two points in space

Is the expansion of space taken into consideration when calculating light or any (Radio to Gamma) wave length distance and speed? I know C is a constant, but my concern is if "space expansion" is ...
0
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2answers
252 views

Reformulated: Universe expansion or collapse

I reformulate the question a little bit because I feel that I was misunderstood. There are cosmic observations that tell us the universe seems to expand. It also seems to expand always faster ...
1
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3answers
289 views

How long does it take for expanding space to double in size

I have been reading about Hubble's constant and trying to make 'sense' of the theory of the expanding Universe. Is is possible that space in the universe expands uniformly? If so, absent of other ...
4
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1answer
205 views

Is the number of wavelengths of light spanning a distance invarient with respect to spacetime distortion?

I was recently asked by a friend how the expansion of spacetime effects photons. I gave him what I feel is a satisfactory general response, but it got me wondering how, exactly to calculate this ...
2
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1answer
76 views

Cosmic bubble collision

I'm reading this review right now. The claim seems to be that when you have an expanding "false vacuum", finite size bubbles form due to phase transition (cause by finite action instantons) (which, in ...
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5answers
979 views

What is the extent of the universe?

Is there any realistic, understandable, provable (even in some extent) explanation/model for the extent of the universe? What is its shape? and Why? I mean physical explanations not philosophical ...
2
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1answer
228 views

Since the universe is expanding, does anything ever occupy the same point in space?

Let's say we can observe expansion in a supercluster. We define origin of our frame of reference at the center of the supercluster. We observe an object/atom at point A at time T. The object is ...
6
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3answers
759 views

At what speed does our universe expand?

Conceivably it expands with the speed of light. I do not know, but curious, if there is an answer. At what velocity, does our universe expand?
2
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1answer
163 views

Virtual particle production in space-time.

Are virtual particles created within existing space-time, or do they create new space-time for them to occupy?
7
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3answers
850 views

How can a quasar be 29 billion light-years away from Earth if Big Bang happened only 13.8 billion years ago?

I was reading through the Wikipedia article on Quasars and came across the fact that the most distant Quasar is 29 Billion Light years. This is what the article exactly says The highest redshift ...
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2answers
308 views

Cosmic Microwave Background (CMB) and its relation to Inertial Frames

We know that the CMB is isotropic when viewed outside of the spinning and revolving earth. Is it homogeneous? Can we relate the CMB to an inertial frame in the Newtonian sense (in which space and ...
2
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0answers
259 views

composition of space expansion and movement as a gauge invariance

suppose i have a space-time where we have one point-like object* which we will call movement space probe or $\mathbf{M}_{A}$ for short, and it will be moving with constant velocity $V^A_{\mu}$ in ...
21
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7answers
4k views

Why is the observable universe so big?

The observable universe is approximately 13.7 billion years old. But yet it is 80 billion light years across. Isn't this a contradiction?
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2answers
659 views

Will the night sky eventually be bright?

I have read that the night sky should have been bright because every spot should end up pointing to a star in the infinite universe but this is not the case because the universe is expanding. I am ...