Remember how Professor Emmett Brown in the legendary Back to the Future assembled the DeLorean (time travel machine)? 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 the time slower, and when you return to Earth, you will find yourself in the future. But what about traveling back in time?
Is travel to the future possible
As Brian Greene, professor of physics and mathematics at Columbia University, explains in a short popular science video for Tech Insider, we know that travel to the future is possible, we just do not 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 - like a neutron star or a black hole - and sort of get closer to the edge of that 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?
The narrowest point is the wormhole or the Einstein-Rosen bridge.
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 the other point of view, don't you agree? So, the main hypothesis worthy of attention is time travel through a wormhole (wormhole).
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In 1935, Albert Einstein and his colleague mathematician Nathan Rosen suggested that there is an impenetrable wormhole that connects two identical, practically flat space-times, thereby creating a "bridge." Physicists today 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 crossing which it is impossible to pass the hole.
In simple terms, this is a bridge from one point in space to another, a kind of tunnel, with which you can significantly shorten the journey from one place in the universe to another. But what will happen if you still manage to pass through that non-static area? 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.
Are there wormholes?
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 may make your head spin a little,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.
If parallel universes exist, it is likely that in one of them, mankind invented spaceships that can travel into distant space.
Anyway, today we do not know if wormholes, the multiverse, and where black holes lead. And if they are really real, then can we pass through them? Most scientists believe not. However, science, armed with imagination, is capable of much. Who knows, maybe the answer to these amazing mysteries of the Universe will be found in the near future.
Lyubov Sokovikova