The space-expansion tag has no wiki summary.
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Evidence for expansion of space [duplicate]
If I understand correctly, Einstein's theory of General Relativity predicted the expansion of space itself, and Hubble confirmed this prediction by observing the red shift of receding galaxies.
I ...
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According to Hubble's Law, how can the expansion of the Universe be accelerating?
Scientists today think the expansion of the universe is accelerating.
According to Hubble's law, objects further away are moving faster than objects closer to us. The further away an object is, the ...
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Conformal time or cosmological time?
Let us assume a flat FRW metric
$$ds^2 = -dt^2 + a(t)^2(dx^2+dy^2+dz^2)$$
Imagine a lightbeam traveling in the x-direction. It travels on a null geodesic with $ds=0$ so that its path obeys the ...
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Is time slowing down and disappearing from the universe instead of the expansion of universe? [duplicate]
Are we fooled into thinking that expansion of the universe is accelerating, when in fact, time itself is slowing?
Or if dark energy does exist?
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What is the theoretical limit for farthest we can see back in time and distance?
13.2 billion years ago the universe was rather small, having started only half a billion years ago. Today, with the help of Hubble Space Telescope, we are able to capture the light of galaxies emitted ...
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Shrink where mass is present theory
This is a philosophical question first and foremost. Let's pretend that space is static e.g. it has a finite size. Let's assume that there are two bodies for example two solid spheres. Now if space ...
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Will the increasing rate of expansion of the universe eventually result in Hawking Radiation suddenly occurring everywhere?
The universe is expanding at an ever increasing rate. Virtual particles are being created and then destroyed everywhere at every moment. As space expands even faster, will a time come when these ...
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Pretty weird question ~!!! any ideas? [closed]
The galaxies in the universe are all flying away from each other. The speeds of nearby galaxies are proportional to the distance the galaxy is away from us. This relation, v=Hd is known as Hubble's ...
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1answer
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Diameter of the universe [duplicate]
Should the diameter of our universe always be more than its age in light years?
As if the distance between any two points in the universe is equal to 13.5 billion light years then the light from the ...
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Cosmic Inflation: Lower Expansion Rate with than without?
When I read the Cosmic Inflation diagram at
https://en.wikipedia.org/wiki/File:Horizonte_inflacionario.svg
which I rotated to make it readable:
where the Hubbleradius, and therefore also the ...
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Does the expansion of the universe soon after the Big Bang affect the amount of time that light takes to reach us?
If faster than light travel is impossible, how is it that light emitted from matter so close together in the time soon after the Big Bang is only now just reaching us? I would assume that there would ...
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Is there anything physically infinite?
I can't think of a single thing that could be infinite.
Because the universe is expanding, isn't it? But there is an ever-changing barrier, so why could there be anything infinite, both ...
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Is it possible that universe might not be speeding up expansion?
I'm not sure but I was thinking of galaxies shrinking with time while still moving apart from each other at almost a constant speed or less (i.e: uniform/slightly decelerating expansion). This may ...
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If everything in existence were increasing in size at some rate, would we be able to detect it?
Would our eyes observe any changes?
What about electronic measurement devices?
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Could entropy explain dark energy?
This was 3rd beer idea, so please bear with me. What if the universe was not actually expanding but the speed of light was slowing? Wouldn't that be indistinguishable to our observations? Either way ...
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How do we measure the range of distant objects despite relativistic effects?
When we observe astronomical objects like distant galaxies there are several complicating factors for estimating the distance:
Relativistic speed result in length contraction
Relativistic speed ...
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1answer
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Could the outer structure of the Universe be made from Antimatter?
Cern recently stated that antimatter may be repelled by matter, much like the opposite effect of Gravity. So is it possible that antimatter is actually repelled to the edges of the Universe to create ...
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Acceleration in the rate of expanansion of the universe due to weakening gravity?
Could the acceleration in the rate of expansion of the universe be due to the weakening of gravitational forces, as the distance between objects continues to increase?
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1answer
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Is dark matter expanding the universe, and creating the structures within it?
If dark matter repelled other dark matter, as well as regular matter(atomic or celestial), and regular matter were repelled by other regular matter "less" than by the dark matter, would not this ...
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Cosmological redshift interpretation
Can the cosmological redshift be interpreted as atomic frequencies increasing by the scale factor as the Universe expands?
This explanation seems closer to the truth than the popular idea that a ...
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When spacetime expands to the point where galaxy clusters are not observable, will there by any interaction?
It's my understanding that in a few billion years, clusters of galaxies won't be able to directly observe one another due to the expansion of spacetime overcoming gravity between those clusters. ...
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1answer
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Why don't orbits expand with the Universe?
Consider two bodies orbiting each other.
As the Universe expands would the distance between them increase?
Most people say that a gravitationally bound system will not expand with the Universe. They ...
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2answers
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About hubble observatory and distant galaxies [duplicate]
According to Hubble observatory, the age of universe is 14 billion years. But, the distant galaxies are about 40 billion light years. How could that simply be possible? That means the information that ...
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2answers
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Why cosmic background radiation is not ether?
why cosmic background radiation is not ether? I mean it's everywhere and it' a radiation then we can measure Doppler effect by moving with a velocity.
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Can space expand with unlimited speed?
At the beginning, right after the Big Bang, the universe was the size of a coin. One millionth of a second after the universe was the size of the Solar System (acording to ...
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1answer
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Galaxies moving away at the speed of light
As an arts student, I really find those cosmological questions hard to understand and hence come here to seek your kind help.
The Hubble constant $H_0$ is estimated to be about 65 km/s/Mpc, where 1 ...
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3answers
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Looking out into the universe means looking back in time - how does that work?
This is a question that has been gnawing on me for many years now. Back a long time ago, as I recall in reference to a scene in a popular science show on TV, I was asked the following.
The claim is ...
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Universe Expansion and two tennis balls
Clear the universe of all matter except for two tennis balls. Place the two tennis balls in the same inertial frame 1 Mpc apart.
Are the tennis balls getting further apart?
Will the tennis balls ...
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1answer
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Size of the Observable Universe [duplicate]
I wanted to know what the observable universe is so I was thinking and I thought, it must be age of the universe times 2.
Well I was wrong. I found on one website that it is 46B LY across in each ...
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1answer
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Speed of Universe Expansion [duplicate]
How much is the universe expanding every second (Earth second)?
If you could be a bit simple in the answer that would be good.
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1answer
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Gravitationally bound systems in an expanding universe
This isn't yet a complete question; rather, I'm looking for a qual-level question and answer describing a gravitationally bound system in an expanding universe. Since it's qual level, this needs a ...
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1answer
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How do we know space is expanding when we are part of space? [duplicate]
From what I understand space itself is expanding, and the Big Bang attempts to describe this expansion at the very early stages of the universe.
This is usually described in a visual way as 2 dots on ...
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1answer
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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 ...
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2answers
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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 ...
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Where is universe expanding? [duplicate]
According to many physicist space, time and universe came to existence after the big bang. The universe is now expanding since after the big bang continuously. So my question is where our universe id ...
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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 ...
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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 ...
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1answer
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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 ...
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1answer
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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 ...
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1answer
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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 ...
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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 ...
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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 ...
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1answer
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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 ...
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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 ...
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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 ...
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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 ...
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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. ...
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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 ...
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1answer
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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)?
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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 ...
