What will happen to the world when the universe is over its last second?

Impossible. There will be no last second in the universe.

The universe is formed by the big **, and the universe is now expanding outward at a speed of 100 seconds, when the universe expands to a certain extent, that is to say, when it can no longer expand, it will begin to contract, and when it shrinks to a certain extent, it will re-occur the big **, of course, this is a very long process.

Scientist**: The universe will shrink infinitely to a point, then expand indefinitely, and there will be two cosmic greats (one shrinking and one expansion), and then a new universe will be formed again. So, the universe can't die! ~

I think that if this is the case, then everything will die and there will be no way to start again, and there is no point in saying anything. (Personally, I don't think the above one makes much sense).

First the matter inside is infinitely compressed until it reaches a singularity, then expands again, and then contracts ......

Personal conjecture).

No one will know, if people don't know by then!

Don't worry about that!

It's a new beginning.

It's all a judgment, and it's not true, so the most accurate answer is not to know! Hehe...

What has become?

I think the result should be as hard as your question!

If time were to be reversed, it would be impossible to prove it, because we would not be able to observe the whole time reversal, after all, we ourselves would be reversing time as a whole, which means that we have lost all memories of this time. Thus the conclusion of this hypothesis is that it is possible for time to rewind as a whole, but because the overall regression of time cannot be observed, the overall regression of time has no meaning for us, and according to Occam's razor's principle, we can assume that it does not exist.

Time rewind for individual particles. If it is possible to rewind the time of a single particle, it is difficult to observe with our observational accuracy. According to the principle of quantum inaccuracy, it is impossible to know the precise trajectory of microscopic particles, so if a microscopic particle does not move forward along the time axis at a certain time, it is also difficult for us to observe.

So, on the other hand, what if a single particle were to move in the opposite direction along the time axis, while other particles in its vicinity were moving in the forward direction along the time axis? Einstein was at least mathematically correct when he thought that time could be considered a dimension consistent with space. In the same way, if a person is crowded with a group of people who are moving forward, can it maintain its backward trend?

It's hard, right?

So the idea is that a single particle running backwards on the time axis will be squeezed by other particles moving forward along the time axis and become forward. In order for a macroscopic object to turn back time, all the particles of the object must be reversed in the time axis.

We have not yet observed a macroscopic object moving in the opposite direction along the time axis, but this does not prove that it does not exist.

Conclusion: It is still too early to say that time can or cannot be turned back, and humans have not really understood time.

Time never goes back.