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

mister i · Jan 23, 2024

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)

PeroK · Jan 23, 2024

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.

PeterDonis · Jan 23, 2024

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.

PeterDonis · Jan 23, 2024

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.

Ibix · Jan 23, 2024

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.

PeterDonis · Jan 23, 2024

Ibix said:

I think you mean @PeroK.

Oops, yes. Will fix.

mister i · Jan 23, 2024

Ibix said:

OP - I assume this is a followup to my comment yesterday.

Thanks and sorry (I didn't see your reply yesterday)

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

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