Linked Questions

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0answers
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Expansion of the Universe (within galaxies) [duplicate]

We know that the universe is expanding. The galaxies are moving far away from each other. But what is happening inside those galaxies or inside the solar systems? Is our Earth moving further away from ...
2
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1answer
141 views

Changes to a Length of Physical Ruler Caused by Gravity vs Caused by Cosmological Expansion of Space

I read here (Feynmann Lectures, Lecture 42) that "Just as time scales change from place to place in a gravitational field, so do also the length scales. Rulers change lengths as you move around." (...
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1answer
54 views

If space expands, why does a liter of water stay a liter? [duplicate]

From observing the universe, we know that space expands. I see what that means on cosmic scales. But what does it mean on smaller scales? If I have a graduated beaker of 2 liter, and 1 liter of ...
29
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6answers
5k views

If spacetime itself is expanding, how could we ever tell?

If space is the measured distance between 2 objects, then saying the space expanded is nonsensical unless we have a measuring stick outside of the space fabric to measure the expansion. 2 objects ...
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0answers
45 views

Can the metric expansion of space theoretically be exploited to do work?

Other questions tackle why space doesn't expand matter, and I've read their respective top answers, but I'm interested in something a little different. Let's say I set up two masses that are 1 Mpc ...
3
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0answers
107 views

Instead of space expanding maybe atoms are shrinking? [duplicate]

Naturally we would not be able to detect this effect directly by measuring the size of objects using rulers because any such ruler would be shrinking too. Also cosmological redshift can be explained ...
2
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1answer
152 views

Would the contraction and expansion of space by gravitational wave produce a Force?

Considering the information found from the LIGO experiment. The gravitational wave causes a contraction(In horizontal direction) and expansion(In vertical direction). Can this be a source of energy. ...
3
votes
2answers
121 views

Light's redshift in a vacuum tube due to expansion

If we have two bodies separated by 1 Mpc, but still connected with a tube then it's evident that these two bodies distance won't change because they are connected (If they're not connected their ...
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1answer
65 views

Why redshift of light occurs between galaxies only? [duplicate]

Edwin Hubble discovery of redshift of distant galaxies make me wonder why is this phenomenon only occurs when object is further away, is it possible that redshift happens in short distance too such as ...
1
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1answer
50 views

Does the expansion of the universe stretch distances in non-radial/angular directions?

At time $t = t_0$ a galaxy is situated at a proper distance $r_0$ and has a proper diameter $D_0$. Setting $a(t_0) = 1$ the proper distance to the galaxy will then of course evolve with the expansion ...
26
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4answers
2k views

Can the Hubble constant be measured locally?

The Hubble constant, which roughly gauges the extent to which space is being stretched, can be determined from astronomical measurements of galactic velocities (via redshifts) and positions (via ...
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1answer
2k views

What does a point in space mean? What we humans think a point in space is in scientific term? (a broader picture)

I am a first year and general student. I Am just curious about the vacuum or space. I just don't get what actually space is. Well, I know our scientists are still working on it but still I just want ...
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4answers
3k views

Expansion of the Universe: is new space(time?) being created or does it just get stretched?

Is new space(time?) being created as the Universe expands, or does the existing spacetime just get stretched? If it just gets stretched, why do galaxies move along with the expansion instead of just ...
52
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5answers
9k views

Can space expand with unlimited speed?

According to this article on the European Space Agency web site just after the Big Bang and before inflation the currently observable universe was the size of a coin. One millionth of a second later ...
2
votes
4answers
1k views

What is a layman explanation for why the wavelength of light increases when space itself expands?

I understand that the universe is generally agreed to be expanding based on observations. What I have read is that space itself is expanding. My question is why does this expansion of space affect the ...

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