In a very long time from now, when we become milkomeda and the galaxies expand...?

Question

will the expansion be faster than the speed of light? If so, how is it possible for this to happen? If these galaxies move faster than the speed of light then eventually astronomers will never be able to find these distant galaxies. If cosmological history is not passed down or somehow lost by this distant future then there would be no way for astronomers to know other galaxies exist.

Answer 1

You're partly right---the parts of the Universe that are receding from us will recede faster and faster if Dark Energy continues to hold sway, and will eventually be moving faster than light with respect to us, and so will be beyond our event horizon.

However, and this is a big however, the part of the Universe that is receding from us is only the part beyond the local supercluster of galaxies.  The Earth, the Solar System, the Milky Way galaxy, the local group of galaxies, the Virgo Cluster, the Coma Cluster and the Great Attractor are not expanding, and will not disappear beyond our event horizon.  That's a lot of real estate.

There was "early inflation" in the first second of the Universe, and it came to an end.  The current regieme of Dark Energy may also come to an end.  This is all very little understood, and relates to the nature of the vacuum and to the as-yet-undiscovered "theory of everything".

Answer 2

There is no known object that travels faster than light.  If a galaxy was receeding from us at the speed of light, which is impossible, we wouldn't be able to see it.

The Milky Way Galaxy and the Andromeda Galaxy may merge in about 3-4 billion years.

Answer 3

>will the expansion be faster than the speed of light?

It is quite possible.

>If so, how is it possible for this to happen?

You have to understand just what it is that the speed of light limit entails. It is true that nothing can move through space faster than the speed of light. However, with the expansion of the Universe, nothing is moving through space, it is space itself that is growing larger. So a pair of galaxies might start out 10 million light years away from each other and soon afterwards (in cosmological terms) be 20 million light years away from each other without actually propelling themselves anywhere, simply because the space between them has been stretched over that time period and left the galaxies farther apart. This stretching can happen faster than the speed of light without causing any relativistic issues.

>If these galaxies move faster than the speed of light then eventually astronomers will never be able to find these distant galaxies.

That is correct.

Answer 4

"Some of the misunderstandings surrounding this topic might come from confusion over what is meant by the universe "expanding faster than the speed of light." However, for the simplest interpretation of your question, the answer is that the universe does expand faster than the speed of light, and, perhaps more surprisingly, some of the galaxies we can see right now are currently moving away from us faster than the speed of light! As a consequence of their great speeds, these galaxies will likely not be visible to us forever; some of them are right now emitting their last bit of light that will ever be able to make it all the way across space and reach us (billions of years from now). After that, we will observe them to freeze and fade, never to be heard from again."

I think cosmological history will be passed down.  However, people may not believe the histories about these galaxies, just as the young people now don't believe any history that occurred before they were old enough to know about it, eg:  the moon hoax advocates and those who insist that the Holocaust didn't happen, no matter how well these historical events were documented.