The most gripping stories in film and literature are based on the idea of time travel and the ability to change the past. While this sounds fiction to most people, Lewis and Clark College astrophysicist Ethan Siegel does not rule out the possibility of going back in time.
Travel in time and space, according to the physicist, originates in such a phenomenon as a wormhole, or wormhole. In the known universe, tiny quantum fluctuations occur in the fabric of spacetime. These include vibrations of energy in both positive and negative directions, often very close to each other. A very strong, dense, positive energy fluctuation could bend space in one way, while a strong, dense negative energy fluctuation could bend space in a completely opposite way. This makes it possible to create quantum wormholes. Imagine a sheet of paper folded in half with a hole in it with a pencil - this is how it should work.
If the wormhole lasts long enough, an object can be guided through it, allowing it to instantly disappear in one place in spacetime and reappear in another, Siegel writes in his Forbes article.
Although every known particle in our universe has positive energy and either positive or zero mass, particles with negative mass or energy are highly possible within the framework of general relativity. Such particles are called exotic in science. Of course, we have not yet found any, but, according to all the rules of theoretical physics, nothing prohibits them from existing.
So, if this substance with negative mass / energy exists, then it is possible to admit the existence of both a supermassive black hole and a negative mass / energy equivalent to it, and, consequently, a wormhole connecting them. No matter how far apart this black hole and its antimatter equivalent, travel between them would be instantaneous. But all this relates to movement in space. But what about the timing? This is where the laws of special relativity come in.
If you are traveling at near the speed of light, you are experiencing a phenomenon known as time dilation. The more you move in space, the less you move in time. Imagine that you had a destination that was 40 light-years away, and you were able to fly towards it incredibly fast - at over 99.9% of the speed of light. Let's say, having reached the specified point, you immediately turned around and returned to Earth. There you will find something strange.
Due to the slowdown in time, you got to your destination in just a year and then came back in the same period. But 82 years have passed on Earth. Everyone you know is either dead or very old. Thus, this is the “easiest” way to travel in time, but only in one direction - to the future. Moreover, the number of travels forward in time depends only on your movement in space. Well, yes - to go back in this way, of course, is impossible.
But if you create a wormhole, things will happen differently. One end of the wormhole remains practically motionless. Let's say it is close to the Earth. At the same time, the other end embarks on a relativistic journey close to the speed of light. If you get into the moving end after it has been on the way, say, a year, then, if you take the speeds from the previous problem, you will find yourself at the static end of the wormhole - on Earth - just a year after its creation, whereas for you themselves will have passed for 40 years.
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If someone created such a wormhole 40 years ago, then you could stand at one end of it today, in 2017, and be in the past - in 1978 (a year after the wormhole appeared).
Alina Nazarova