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Remember how Professor Emmett Brown put together the DeLorean (time travel machine) in the legendary Back to the Future? Unfortunately, the adventures of everyone's favorite heroes in the past will remain fiction. But that doesn't mean time travel is impossible. The main thing that any physicist will tell you is that you can only go to the future.
However, according to scientists, there are two ways of time travel, but they are very different from each other. Since the same laws of physics operate in the Universe as on Earth, according to the first method, if you move at a speed close to the speed of light, and then turn around and go back - for example, on a ship of imagination - then the clock on your hand will count down the time slower, and when you return to Earth, you will find yourself in the future. But what about travel back in time?
Is it possible to travel to the future
As Brian Greene, professor of physics and mathematics at Columbia University, explains in a short science fiction video for Tech Insider, we know that travel to the future is possible, we just don't have the technology to do it right now. Albert Einstein was the first to understand that theoretically, having escaped from the Earth at a speed close to the speed of light and returning back to the future, Albert Einstein realized a hundred years ago. In general relativity, he also showed that if you hover next to a strong source of gravity - for example, a neutron star or a black hole - and, as it were, get close to the edge of this object, for you time will slow down very slowly relative to everyone else. Therefore, upon returning home, you will find yourself in the distant future. From the point of view of physics, there is nothing to argue about. But what about travel back in time?
Travel to the past and the future
For many years now, there has been a debate among physicists about whether it is possible to go to the past. The controversy arises, as you probably already understood, because most physicists consider it impossible. But the more interesting is the other point of view, don't you agree? So, the main hypothesis worthy of attention is time travel through a wormhole (wormhole).
Worm-hole- a hypothetically existing region in space-time, which is a "tunnel" in space at each moment of time
In 1935, Albert Einstein and his colleague mathematician Nathan Rosen suggested that there is an impassable wormhole that connects two identical, almost flat space-times, thereby creating a "bridge." Today physicists view the bottleneck of the Einstein-Rosen bridge as the event horizon of a black hole. Presumably, between the right and left parts of the horizon there is a special non-static area, without overcoming which it is impossible to pass the hole.
Black hole event horizon- a region in space-time, a kind of space prison, once it is impossible to get out, even for photons of light
In simple terms, this is a bridge from one point in space to another, a kind of tunnel, with the help of which you can significantly shorten the journey from one place in the universe to another. But what will happen if you still succeed in passing through that non-static region? Physicists assume that as a result of passing the Einstein-Rosen bridge, you will no longer simply move from one place in space to another, but will pass from one moment in time to another. Go to the right - you will find yourself in the past, to the left - in the future. Or vice versa.
Do wormholes exist?
If you are somewhat confused by this question, then it is completely in vain. Let me remind you that until April 12, 2019, black holes - just like wormholes today - were considered hypothetical objects.That all changed when scientists were able to photograph the event horizon of the space monster Sagittarius A *, a supermassive black hole located in the center of the Milky Way galaxy. Therefore, it is possible that someday scientists will be able to prove the existence of wormholes. But even if wormholes exist, we do not know if it is possible to walk through them. Also, as we do not know what happens beyond the black hole's event horizon. The world famous theoretical physicist Stephen Hawking suggested that black holes could be portals to other universes. Read more about this in our material. It is important to understand that such a theory can be a little dizzy, since it assumes the existence of a multiverse - an infinite number of worlds. Moreover, in each of these worlds, the laws of physics, different from our Universe, can operate. Or not.
Either way, today we do not know if there are wormholes, the multiverse, and where black holes lead. And if they are really real, then can we get through them? Most scientists believe not. However, science, armed with the imagination, is capable of much. Who knows, maybe the answer to these amazing mysteries of the Universe will be found in the near future.