Can the "creation" of space in the Universe affect the speed of light?

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mister i
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TL;DR Summary
Can the expansion/creation of space in the universe affect the speed of light over long distances? (dividing the space traveled (including expanded space) by the travel time).
Can the expansion/creation of space in the universe affect the speed of light over long distances? (dividing the space traveled (including expanded space) by the travel time). If the Hubble constant is valid throughout the universe, it follows that from a certain Megaparsec of distance, galaxies should separate from us faster than light. Could the same thing happen to light? (I understand that not because this would imply an observer, but if we could see them we would see the galaxies move slower because the trail of their light would be slower)
 
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mister i said:
TL;DR Summary: Can the expansion/creation of space in the universe affect the speed of light over long distances? (dividing the space traveled (including expanded space) by the travel time).

Reference: https://www.physicsforums.com/forums/cosmology.69/post-thread

Can the expansion/creation of space in the universe affect the speed of light over long distances? (dividing the space traveled (including expanded space) by the travel time). If the Hubble constant is valid throughout the universe, it follows that from a certain Megaparsec of distance, galaxies should separate from us faster than light. Could the same thing happen to light? (I understand that not because this would imply an observer, but if we could see them we would see the galaxies move slower because the trail of their light would be slower)
In cosmology, the speed of light is constant (invariant) when measured locally. On cosmological scales, the speed of light over longer distances is not well defined.

In this posts, as in previous posts, you are trying to squeeze modern cosmology into a classical framework, using classical concepts. If you want to learn about cosmology, you will have to open your mind somewhat.
 
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mister i said:
the expansion/creation of space
Is not a real physical thing, it's a coordinate artifact, so it can't affect anything.
 
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mister i said:
If the Hubble constant is valid throughout the universe, it follows that from a certain Megaparsec of distance, galaxies should separate from us faster than light.
This "separation speed" is a coordinate speed and has no physical meaning. This was pointed out in one of your previous threads. As @PeroK [Edit--fixed] has commented, you are using a flawed conceptual scheme, and that's not going to change no matter how many questions along these lines you ask.
 
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  • #5
PeterDonis said:
As @Ibix has commented, you are using a flawed conceptual scheme, and that's not going to change no matter how many questions along these lines you ask.
I think you mean @PeroK.

OP - I assume this is a followup to my comment yesterday. The best way to ask your question is to ask if there are regions of the universe that will always be outside the future lightcone of some distant galaxy, no matter how far into the future we wait. Yes there are. Light from them will never reach us.

If you choose to describe spacetime in terms of "expanding space" then yes, this can be interpreted as the distance growing too fast for light to reach us. But describing this as space being created is wrong - you are looking at different sections of spacetime, not one "piece of space" that is growing.
 
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Ibix said:
OP - I assume this is a followup to my comment yesterday.
Thanks and sorry (I didn't see your reply yesterday)
 
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1. Can the expansion of space in the Universe affect the speed of light?

No, the expansion of space does not affect the speed of light itself. The speed of light in a vacuum, denoted as 'c', is a constant at approximately 299,792 kilometers per second. This speed remains constant regardless of the expansion of space. However, the expansion can stretch the wavelength of light, which is observed as redshift, but this does not change the speed at which light travels.

2. What is redshift and how is it related to the expansion of the Universe?

Redshift occurs when the wavelength of light or other electromagnetic radiation from an object is increased (stretched) as it travels through expanding space. In the context of the Universe, as space expands, light traveling through space stretches to longer, redder wavelengths. This is a key observation that supports the theory of the expanding universe, indicating that galaxies are moving away from us.

3. Does the expansion of space mean that distant galaxies are moving away faster than the speed of light?

Yes, in some cases, the space between galaxies can expand faster than the speed of light. This does not violate Einstein's theory of relativity, which states that nothing can travel through space faster than light. Instead, it is the space itself that is expanding, causing galaxies to recede from each other at speeds that can exceed that of light. This is why we observe some galaxies that are so far away and moving so fast that their light will never reach us.

4. How does the expansion of the Universe affect our observations of distant objects?

The expansion affects observations in several ways. Firstly, as mentioned, there is redshift, which makes objects appear redder and can be used to measure the rate of expansion. Secondly, the expansion can make distant objects appear dimmer and more difficult to observe, as the light is spread out over a larger area. Lastly, the expansion can limit the observable universe, as there may be regions from which the light will never reach us due to the rapid expansion of space.

5. Is the speed of light always constant, even in non-vacuum conditions?

No, the speed of light is only constant in a vacuum. When light travels through other mediums, such as water or glass, it slows down. This slowing is due to the light interacting with the atoms and molecules in the medium. However, once it leaves the medium and returns to a vacuum, its speed returns to the constant c (299,792 km/s).

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