Regarding the theory of the world line, Su Yuan and they have been in contact for a long time, and they also know about it.

The principle of the time machine is not mentioned much in Gaia's database, probably because it is just a space shuttle.

However, these are difficult for Gao Jun and Charlene, with a rough outline, and the filling of details has a new world compared to the state of complete unknown.

Gao Jun looked at Su Yuan and Ji Ye Hao, who were sitting below and listening, and suddenly felt a sense of accomplishment, and wrote a "1" on the blackboard.

He cleared his throat and said: "According to the view of special relativity, the time of a moving object is slower than that of a stationary object, and scientists explain it because space-time is a whole, when two objects are stationary in the same place, they only move on the time axis, and the progress of the motion is the same, and when an object is stationary and only moves on the time axis, and another object moves in both space and time, the stationary object moves faster on the time axis than the moving object." ”

"Someone has come up with the first type of time machine, if a machine that can move at high speed is invented, one of them is sent out of the earth at a very high speed, and after the movement and then back to the earth, he will find that he is back to the 'future' of the earth. ”

"To give a good example, suppose there are twins A and B, when they are twenty years old, they leave A on Earth, and B takes a high-speed moving object into the universe and comes back, because B's speed passes faster than A's, so B is only 30 years old, and A is 50 years old, relative to B. It took him ten years to come to thirty years after the earth. ”

"It's the equivalent of a one-way low-level time machine. ”

As soon as Gao Jun finished speaking, Xia Linfeng smiled at Su Yuan and said, "But there is an important argument involved here. That's the twin preintendents!"

"The twin son Fei Miao thinks: from the perspective of B, assume that the earth is stationary. He does move at high speed, but the problem is that if B is assumed to be at rest and different, but the earth and A are moving at high speed, there is a contradiction, the former statement that B in motion should be younger than A, and the latter that A in motion should be younger than B. ”

"This debate has been going on for a long time. Until now, some people have not been able to understand this phenomenon. But in reality, the twin puppets are the result of a misunderstanding of the theory of relativity. ”

Gao Jun said: "The important thing about the theory of relativity is the word 'relative', relative to themselves, they themselves do not feel any difference in the passage of time, they choose to refer to different things, this is the difference, and only the moment they meet, this comparison will be meaningful." B is moving at high speed relative to A and the earth This is best understood, because human manipulation is like that. ”

"But actually. Whether you choose A as a reference or B as a reference, the final conclusion is one, B is younger than A!"

At this time, Gao Jun drew a time-space map on the blackboard. The motion of A and B in the four-dimensional space is drawn into a plane space-time diagram.

"You see, if you assume that B is always stationary different, in B is far from the earth. That is, when the earth moves away from him, he sees that A is younger than himself. And then B starts to turn back, and the earth starts to turn. It was in the process of turning this corner that he suddenly saw that A had suddenly aged, and then the earth continued to approach him, and he saw that A was aging slower than himself, and the two met, and the result was that he was still twenty years younger than A. ”

"Different reference frames were used to depict the world line in the space-time map, and the final result was that B was younger than A. So the twin feints are essentially derived from a misunderstanding of the theory of relativity. ”

In addition, in the general theory of relativity, in addition to the different time flow of moving objects, the effect of gravity will also cause the distortion of space-time, and the large gravitational force will cause the space to distort sharply, and time will go slowly. That is, the object in the high altitude travels faster than the object on the ground, so extend to the edge of the black hole, where the time should be indescribably slow. ”

"If B's vehicle not only travels at high speed, but also circles the edge of the black hole, then the greater the time span for him to reach the future of the Earth. ”

Black holes are freaks of the universe, and inside black holes, almost all known physical laws are invalid, and even the concept of space has no meaning. To say that a black hole is small is to stand outside the black hole, from the scale of our universe, but in fact, how big is the inside of the black hole, because the laws of space are different, and it is impossible to compare the size of the black hole with the universe in which we are located.

In other words, if a black hole were a standard sphere, its entirety would be a long-term projection of the event horizon to the central "singularity", with the internal definitions of time and space in unison. This has nothing to do with this article and will not be repeated.

Charlene shook her head and said, "But whether it is an object moving at high speed, moving around a black hole, or a combination of the two, they are all one-way time machines leading to the future, and the scale that can be crossed is also limited. This kind of low-level time machine doesn't have much practical significance. ”

Gao Jun wrote a "2" on the blackboard and said: "Kurt Gödel, a mathematical genius who was a contemporary of Einstein and a good friend of Einstein, once proposed an idea: he thought that if space-time was spiral-curved, and there was an axis in the middle of space-time, if you could manage to stay still when space and time rotated around this axis, then you could go anywhere in space-time." ”

But now scientists realize that space-time does not revolve around an axis, and Gödel's idea is impossible. ”

Then he wrote a "3".

Professor Frank Tipler, a modern physicist, proposed that we cannot make the universe rotate, but we may be able to try something on a small scale, just by creating a relatively small rotating cylinder, the cylinder rotates at nearly the speed of light, and then the time and space around the cylinder will be entangled by it, and space will become time, and time will become space, (similar to the internal time axis of a black hole, Space axis swap), you can create a time channel inside the rotating cylinder, and when people approach the cylinder and rotate around it, they can travel through time and space. Go back in time when spinning down. Upward rotation reaches the future - from which he also conceived a treatise on "The Rotating Cylinder and the Destruction of the Overall Causal Relationship". ”

"This is the most groundbreaking time machine theory of modern times, but it's a pity. This is also unrealistic, and that paper was not written. ”

Charlene's task was as if it were specifically to veto Gao Jun's idea of giving an example. The first two ideas were rejected, and the third was inevitable.

"The rotating cylinder needed to break time and space would be an infinite cylinder, as difficult as the creation of the universe," she said. So you need to try to shrink the structure of the cylinder, but Tipler finds that it is not possible, because when you try to make a time machine, you will find that before the time machine is formed, you will pull a hole in time and space, create a singularity, and you need to instill the mass of the entire universe into it, and that is to create a universe. ”

"Fourth. It's the wormhole concept often used in science fiction!"

There are two types of wormholes, one is called Lorentz wormhole and the other is called Euclid wormhole. The former is a space-time tunnel that can be passed, it is a long-term conduit through which it can travel to other universes or jump in this universe, and even to the past and the future.

In the imagination of cosmologists, the early universe had many natural Lorentz wormholes, as well as many pipes to connect to the parent universe, but these wormholes were decaying and closed. It is already difficult for humans to use, and even the Lorentz wormholes that exist in the universe are small enough for particles to pass through. Therefore, the scientific community is pessimistic about this kind of wormhole.

And the Euclid wormhole, it is a wormhole that passes through instantaneously. As soon as you enter the cave, you will reach the exit, but there are too many uncertainties in its appearance to be difficult for humans to grasp.

Charlene said: "Physicists have proposed that there are wormholes at the quantum level. We need to use negative energy to expand it big enough to tear apart time and space. Negative energy will prevent gravity from destroying wormholes, but the negative energy required is not something that humans can create today. ”

……

"The fifth kind of time agency thinks. Cosmic string theory: There is a thin line of energy across the universe - the cosmic string, and Richard Gott believes that a very strong gravitational force around the cosmic string is enough to create a space-time tunnel. ”

"But when two cosmic strings come close together at high speed, black holes can be created, and if you want to go back a year ago, you need half the mass of the Milky Way. So it's not really connected. ”

****************

"So much has been introduced, do you have a practical idea?"

Su Yuan looked at the blackboard full of words and asked curiously.

"Yes!" Gao Jun nodded, "There is an idea on Earth to use quantum non-locality, using quantum non-locality (quantum entanglement) to send information to the past, which is also the method used in Gaia's hometown. ”

The so-called non-locality of quantum is the characteristic of cross-regional communication between two quantum beings in an entangled state, which is a manifestation of quantum entanglement. Two quanta in an entangled state, no matter how far apart they are, as soon as one quantum changes state, the other quantum entangled with it must change with it. This change is instantaneous, regardless of distance. Some people think that it cannot exist beyond the speed of light, but in reality it does exist.

It's like A and B are mother and daughter, and daughter B gives birth to a child in the United States, and at the moment when B becomes a mother, A in China is immediately promoted to a grandmother.

"Quantum A and quantum B in an entangled state, if A is on Earth and B is on the Moon, when the state of A is artificially changed, B on the Moon will also make corresponding changes at the same time. Their information travels faster than the speed of light. ”

"Through this principle, there are conditions to send information to the past, and this is the causality of breaking events in the quantum realm......"

"Is it possible to send a message to the past?"

Su Yuan's face was full of disbelief, no matter what, the time of receiving information and communication is later than the time of sending, sending information to the past, wouldn't it be received first, and then sent?

In her traditional consciousness, there simply seemed to be the means to do this.

"No, it can be done. ”

This time, Charlene did not reject Gao Jun's idea, but agreed.

"The results of some experiments on our planet hint at the existence of this possibility, and Gaia's hometown has proven it correct, and used it to create a 'generation time machine' that can travel through the same world. (To be continued......)