Time Travel is Possible
Modern astronauts, as we know, are already doing so. However, they travel so far only in the future. And for a split second. But who knows – maybe one day we will be able to fly for years or even centuries ahead or, alternatively, pull over forelock of our five-year grandfather? But let’s start from the beginning.
Stop the Moment!
Time in the empty space of the cosmos and on earth flies differently. It is known to every schoolboy. The stronger the gravity of any object, the faster time passes in its vicinity. This is due to the fact that distorted by gravity fabric four-dimensional space-time. On the other hand, Einstein showed that the higher the rate – the greater the weight. Thus, he lives in time, on the whole 1/50 of a second ahead of us.
The theory of relativity tells us that the time machine that will take us into the future, you can create. You enter into it, waiting. Come and discover that the world passed the century. Technologies for this yet, but the science is known – it is possible.
However, it will have to accelerate to speeds close to the speed of light. Is it any wonder that Time Machine is nothing more than a spaceship, because, according to general relativity, space and time are inextricably linked (the question of how to disperse to such a breakneck speed to keep intact your body and the ship itself while it is not necessary). But whether a person will be able, to commit such a journey back into the past?
The first hints of the fact that the laws of physics allow people to travel in the past, appeared in 1949, when the mathematician Kurt Gödel found a new solution to Einstein’s equations, and in fact – a new structure of the space-time, which is quite acceptable from the standpoint of general relativity. However, based on Gödel’s equations, the universe must rotate as a whole, and not expand with acceleration – which, as it turned out since then, not true.
In recent years, scientists have suggested other ways for potential time travel – the curvature of space-time. However, analysis of the microwave background and other data show that the universe has never been so twisted that such travel becomes possible. However, there is a workaround.
What is the past?
According to general relativity, there is not only some kind of the same for all observers, the universal measure of time, but there is no need, in certain circumstances, even to observers agreed on a single sequence of certain events. Assume that time Alpha Centaur moves at the same speed as the Earth and planet where live ETs has the same mass and moves with the same speed). In 2014 he held the Olympics in Sochi. Suppose also that in 2015, will open the interplanetary chess tournament on Alpha Centauri. Which events took place earlier?
From the point of view of the earthlings – the Olympics. After all, the light from the Earth to Alpha Centauri will go four years. Going faster than light, you would be able to attend the Olympic Games and fly to the tournament, and then once again to return to Earth … before the Olympics. Naturally, in theory – if we find a way to move faster than light.
Move faster than light, based on the theory of relativity is known to be impossible. As we approach the light barrier to break up the object takes more and more energy. At one point – the theoretical achievement of the speed of light – it would take an infinite amount. In addition, the body, which has reached this speed, must acquire infinite mass.
It was then and possible workaround. It lies in the potential to distort space-time. For example, so that opened a short way from the Olympics to the chess tournament. You will not move faster than the speed of light – but in space move faster.
In 1935, Albert Einstein and Nathan Rosen wrote a paper in which he argued that general relativity allows the existence of space-time bridges shackles – wormholes.
Maintaining the integrity of the wormhole requires a great deal of energy, and the theory predicts that they cannot survive long enough to pass through them could the spacecraft. This bridge can to collapse, and the ship will be lost somewhere in the singularity.
However, scientists admit the idea that the technically advanced civilization could hold such an open hole and the right time. But how this can be achieved, the question is quite vague.
It is worth mentioning that all matter, to which we are accustomed, has positive energy density, which gives space-time a positive curvature that resembles a sphere. And for the space-time deformation, which would allow us to travel back in time, we need matter with negative curvature – ie, with a negative energy density. Quantum mechanics, as we know, the existence of a negative energy density permits (under the condition that this negative offset by positive in other areas), and allows the theoretical possibility of warp space-time.
Present is not easy. To do this, astrophysicists often cite the example of the hill. If you dig a big hole and throw the earth out of her on the edge of the pit, in the end, you get not only the pit, but the hill. In this case, the hill and is a metaphor for this positive energy and a pit – negative.
Black holes are not only
Scientists cautiously suggest that the original analogue wormholes may possibly be a black hole. The fact that most of the space-time is almost flat. It is strongly deformed only in black holes. A black hole distorts the space-time around itself, which forms a kind of funnel, hole conical shape.
Gravity in the immediate vicinity of a black hole is so huge, that the space-time, it essentially ceases to exist or is distorted so much that practically stops. In addition, some black holes rotate at light speed. As a result, the space-time rolls up almost in the tube in the hole. Maybe, entering into a black hole, we could go through its narrow tunnel and be … in the past, or, for example, in another universe?
The most famous physicist of our time – Stephen Hawking – sure, it’s impossible. Even if a spaceship in some incredible way (breaking unharmed a huge effect of gravity) will be able to get into the center of the black hole, it will be in the singularity and simply cease to exist.
However, many other scientists believe that, once the black hole, under certain conditions, you can still survive, and even looking for ways to do it. Of course, it looks eccentricity. But the history of science knows many examples of such eccentrics invented the airplane, or went to the moon.
Professor of Astrophysics at Princeton University Richard Gott (Richard Gott) – fan of time travel. It creates a theoretical time machine design and even claims to have found a solution to travel into the past. After some astrophysicists, Gott believes that the natural time machine – is the center of a rapidly rotating black hole. But he also understands how fragile it may be a transport.
However, Gott found a less dangerous potential analogue center of a black hole – a phenomenon which is called cosmic strings. Cosmic strings – it hypothetically existing folds of space-time, thin strands of energy remaining after the Big Bang. Their width is less than the atomic nucleus, but they have a phenomenal density. Such a string length of 1 m would have had more gravity than the Earth as a whole, and would create a big bend. Gott found that the interaction of fast moving string can lead to the appearance of a natural time machine.
Gott’s calculations have not yet been confirmed by observations, but scientists are trying to prove that these strings exist. However, even he says that finding these two strings, which would have been next to each other, it is practically impossible. Therefore Gott draws attention to the different theoretical framework, on the ring space that could generate closed strings. Despite the lack of evidence of their existence, a direct error in Gott’s no theory. In addition, the inside of the ring will be … again a black hole. And in general, to manage the system with such grandiose gravity, would need the energy resources of entire galaxies.
Back to the past cannot stay
But if admits quantum time travel theory of our – macroscopic – scale? Stephen Hawking says that, at first sight, permits. This is evidenced by the Feynman path integrals (Feynman diagrams are that they replace the definition of the unique, the only possible path of movement of any elementary particle is the sum total of an infinite number of possible trajectories of its motion). After all, they cover all possible scenarios, and, therefore, allow the existence of such a distortion of space-time that is needed to travel into the past. Therefore, to say that such travel is not possible, in principle, impossible.
Heavy particles are dispersed in a collider at the European Center for Nuclear Research (CERN), or in the National Laboratory. US Fermi reach rate of 99.99% of the speed of light. However, no matter how much plant capacity was increased to exceed the light barrier will not succeed.
Ay, guests from the future!
But if so, why are we still not visited by guests from the future? A popular point of view that the future of civilization is so advanced that he considered it inappropriate to disclose the secret of time travel so unreasonable beings like us. What, if any contemporary enthusiast will want to go back in time and discover the secret of the Nazi atomic bomb? ..
Such different story
It may be that the story is a strictly fixed sequence of events, so even if you go back in time, you will be doomed to do the same things they were doing before. Otherwise, returning in the future, you may even find that you simply do not exist … or not you’re loved ones, or not the country in which you live, etc. This drama is well described in the famous sci-fi short story by Ray Bradbury A Sound of Thunder, which the protagonist, making a journey into the past, accidentally crushed a butterfly – and came back and found out that his family written in another language, and power instead presidential- liberal is a dictator. In the natural sciences, this term is called – the butterfly effect: a slight impact on the chaotic system can have large and unpredictable consequences somewhere else and at another time.
Another possible way to resolve the paradoxes of time travel can be designated as the hypothesis of alternative history. When the time travelers go back in time, they fall into the alternative stories that are different from the one they know. Many scientists today talk about the possible existence of the multiversity, which may include all of these – and an infinite number of others – the last options, branching into an infinite number of worlds…
At first glance, this hypothesis is reminiscent of Feynman quantum mechanical equations. But there is an insoluble contradiction between them. In Feynman integrals each path includes a fully space-time, and all that is in it. And, as we found out, in the framework of the submission of the missile through the curved space-time could even go back in time. But the missile itself when it would have remained the same, his space-time and, consequently, in the same story. Therefore Feynman integrals rather speak in favor of the hypothesis of a fixed past.
Modern science is in the travel opportunities in the past questioned. But still we do not recommend to argue with someone on this matter: suddenly that someone argues, knowing in advance the future..?
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