Cryosleep.
A lot of people believes that we will be able to achieve cryosleep like in sci - fi movies.
In the movie Avatar, Passenger, Aliens, Interstellar etc, we have an entire pods of human beings put to sleep.
Cryosleep is basically impossible because when a person is frozen, they would be sleeping forever because we have no means to restart our brain.
Freezing causes water to crystallize. The ice crystals that form will completely destroys the cell's structure and end up shredding your tissues.
There are only a handful of animals on Earth that can be fully frozen and make it out alive.
Hibernation may be possible by drastically reducing a person’s metabolism. The key to these technologies is finding ways to slow down cell replication with the body during these periods, which effectively tricks the body into forgetting that it is aging.
There are chemical compounds and medicines that are being examined but they will be difficult to test without accidentally killing a lot of the subjects. Realistically, we are still a long way off from but it’s not completely off the table.