Is time travel possible?

Writing this post inspired me to the topic Physics of the impossible - or rather, a passage about the relativity of the impossible.

Is time travel possible?

Not. At least in our reality. If it were possible, we would already know about it - the reality would change and we would know the precedents of the appearance of travelers from our future in our past. However, the story does not report anything like that.
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There is, however, one “but”: my statement is true under the condition of linearity of time, i.e. if it is an infinite continuous line.

It is quite possible that time is capable of branching: this means that having returned to the past, the time traveler at the point of his appearance creates a branch, which follows a new scenario, taking into account his presence. But this automatically means two things: firstly, the possibility of the existence of an unlimited set of parallel universes, secondly, that you cannot fix anything back to the past, because the reality from which the traveler went into his past will remain unchanged - everything he can do , it is to create another reality where things will go differently. And that is not a fact that is more successful.

And the most interesting thing in assuming the possibility of "reproduction" of the universes - and can they come back together?

In this I see a parallel with the discussion of the motion of the Universe after the Big Bang: some scientists claim that it will expand indefinitely until it is scattered infinitely far; others - that sooner or later the Universe, having reached a certain limit, will begin to shrink until it collapses completely and creates a new explosion, restarting the cycle. Personally, this option seems to me more likely and natural, chtoli.

But is it then possible that parallel universes generated by time travel will, like rays from one point, eternity endlessly scatter from each other? I think no. If we accept the version of a shrinking Universe, then its various alternative variants must also be subject to this “pulsation” - which means that inevitably they will come to an end sooner or later - that is, they will collapse. In other words, the diverged branches of time will meet again at one point - at the point of the Big Bang.

In addition, the possibility of time branching presupposes the existence of one “correct” universe, which is uniquely identified by just such - and this is our universe, and many “wrong” ones. It is very easy to identify them - if suddenly in the Stone Age an army arises on tanks and aircraft carriers, then you are in a parallel reality.

But I got distracted, of course. The genesis of parallel universes is a very interesting topic - if you allow them to exist.

I will return to the question asked in the subject and answer it a little wider: if time travel is possible, then only as time travel and reality. Because the fact of movement in time (if it is possible) opens up a new reality.

Just a journey through time - within the framework of one reality - is an unattainable dream.

So if you want to create a time machine to correct something, for example, in your past, think about it - your past will not change anyway.

UPD User dimonline pointed to a very important thing that I missed first: people cannot consistently travel to the same past, because each time they appear there will create a separate branch of time.

And this means that on such alternative branches there could be a group of people, one person or even an inanimate object from the future - even a molecule accidentally transferred into the past is enough to launch an alternative branch.

This kind of presence people in this alternative reality could not notice or not recognize.

And this means that my statement above, that we live in the only correct universe, is not true. We can live in this kind of branch. As for me, it is very sad :(