Su Yuan and his colleagues have learned a lot about the theory of the world line after they have been in contact with it for a long time.

The manufacturing principle of the time machine is not mentioned too much in Gaia's database, perhaps because it is just a cosmic shuttle.

However, these things are not difficult for Gao Jun and Xia Linfei to have a general outline and the filling of details is relatively unknown.

Gao Jun looked at Su Yuan and Ji Yehao who were sitting below listening to the lecture, 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 moving objects travels slowly than the time of a stationary object. Scientists' explanation for it is because space and time is a whole. When two objects are stationary in the same place, they only move on the time axis, and the movement progress is the same; and when one object is stationary only moves on the time axis, the other object moves in both space and in the time axis, the motion of the stationary object on the time axis is faster than that of the moving objects."

"So some people proposed the first type of time machine, suppose that a machine that can move at high speed will be invented, and one of the people will be sent out of the earth at an extremely high speed. After moving, he will find that he will return to the earth's 'future'."

"To give an appropriate 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 to circle the universe. When they come back, because b's speed passes faster than a, b is only 30 years old, but a is already 50 years old. Compared with b. It took him ten years to reach the earth's thirty years later."

"This is equivalent to a one-way low-level time machine."

Gao Jun just finished speaking, Xia Linfei smiled at Su Yuan and said, "But here involves an important debate. That is, twins pretend to be a fool!"

"Twin Son-Pan Mu believes that: from the perspective of b, assuming that the earth is still, he does move around at high speed for a circle, but the problem is that if b is assumed to be stationary and different, the earth and a are moving at high speed, there is a contradiction between this. The former statement is that the moving b should be younger than a, while the latter statement is that the moving a should be younger than b."

"This debate has lasted for a long time. Until now, people still cannot understand this phenomenon. But in fact, twins pretend to be misunderstood by a misunderstanding of the theory of relativity."

Gao Jun said: "What is important in the theory of relativity is the word "relative". Compared to themselves, they themselves do not feel that there is any difference in the passage of time. The choice of reference is different, and this kind of comparison will only be meaningful when they meet. This is the best understanding of the high-speed movement of a and the earth, because this is how artificial operations are."

"But in fact. 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 space-time chart on the blackboard and drew the movement of a and b in the four-dimensional space into a plane space-time chart.

"You see, if you assume that b is always still and different, when b is away from the earth. That is, when the earth moves away from him, he sees a younger than himself and he ages faster! Then b starts to turn back, that is, the earth begins to turn. It is during this turn that he suddenly sees a suddenly aging, and then the earth keeps approaching him. He sees a slowly aging than himself. When the two meet, they are still twenty years younger than a."

"Select different reference systems to describe the world line in the space-time diagram, and the final result is that b is younger than a. Therefore, the twins pretend to be murmur is essentially due to their misunderstanding of the theory of relativity."

"In addition, in general theory of relativity, in addition to the different time elapse of moving objects, the effect of gravity will also cause distortion of space and space. The large gravity will cause severe distortion of space and time to move slowly. That is, objects at high altitudes move faster than objects on the ground, so when extending to the edge of the black hole, the time there should be indescribable slowness."

"If the aircraft that B is riding not only moves at high speed, but also goes around the edge of the black hole, the greater the time span of the future he can reach the earth."

Black holes are freaks in the universe. Inside the black hole, the known physical laws are almost invalid, and even the concept of space has no meaning. To say that a black hole is small, it is standing outside the black hole. From our cosmic scale, it is actually impossible to compare the size of the black hole with the universe we are in because of the different laws of space.

In fact, the radius r of a black hole is not a spatial scale, but a time axis! In other words, if a black hole is a standard sphere, its whole is a long time projection of the horizon leading to the central "singularity", and the internal time and space definition are just in tune. This has nothing to do with this article and will not be repeated.

Charlene shook his head and said, "But whether it is a high-speed moving object or moving around a black hole, or a combination of both, they are all unidirectional time machines leading to the future, and the scales that can be crossed are very limited. This type of low-level time machines do not have much practical significance."

Gao Jun wrote a "2" on the blackboard and said: "Kurt Gödel, a mathematical genius who was Einstein's same age as Einstein and was a friend of Einstein, once proposed an idea: He believed that if space-time and space were spiral-curved, and there was an axis in the middle of space-time, when space rotated around this axis, if you could try to keep it still, then you could go to any time and place in space-time."

"But now scientists realize that the universe and space-time do not rotate around the axis, and Gödel's idea is impossible to achieve."

Then he wrote a "3".

"Modern physicist Professor Frank Tippler proposed: We cannot let the universe rotate, but we may be able to make some attempts in a small range. We just need to create a relatively small rotating cylinder, which rotates at the speed of light. At this time, the time and space around the cylinder will be affected by it, and space will become time, and time will become space, (similar to the time axis of the black hole, and the space axis exchange), and time channels can be generated inside the rotating cylinder. When people approach and rotate around it, they can travel through time and space. When they rotate downward, they will return to the past. When they rotate upward, they will arrive at the future - thus he also imagined writing a paper "The Destruction of the Rotating Cylinder and the Overall Causal Relationship."

"This is the most pioneering time machine theory in modern times, but unfortunately. This is also unrealistic, and the paper was not written."

Charlene’s task is as if it is specifically to reject the idea given by Gao Jun. Both of the first two ideas were rejected, and this third one is inevitable.

She said: "The rotating cylinder needed to break the time and space will be infinitely large cylinders, which is as difficult as creating the universe. So you need to try to reduce the cylinder structure, but Tipler found that it was impossible, because when you try to create 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 need to instill the mass of the entire universe into it, that is to create a universe."

"The fourth type is the wormhole concept that is often used in science fiction novels!"

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

In the early conception of cosmologists, the universe had many natural Lorentz wormholes and many pipelines connecting the mother universe, but these wormholes were all decayed and closed. It was already difficult to use for humans. Even the existing Lorentz wormholes in the universe were so small that they were only enough for particles to pass through. Therefore, the scientific community was pessimistic about this wormhole.

The Euclid Wormhole is a wormhole that passes instantly. It reaches the exit as soon as it enters the hole, but there is too much uncertainty in its appearance, which is difficult for humans to master.

Charlene said: "Physicists propose that if there is a wormhole at the quantum level, we need to use negative energy to expand it to a large enough level to tear open time and space. Negative energy will prevent gravity from destroying the wormhole, but the negative energy required is not something that humans can create now."

...

"The fifth time mechanism thinks. Cosmic string theory: There are thin energy lines that cross the universe - cosmic strings. Richard Gott believes that surrounding the cosmic strings with extremely strong gravity is enough to create a space-time tunnel."

"But when two cosmic strings approach at high speeds, black holes may be generated. In addition, if you want to go back a year ago, the mass required is half the mass of the Milky Way. So it is also unrealistic."

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

"I have introduced so many things, are there any practical ideas?"

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

"Yes!" Gao Jun nodded, "There is an idea on Earth that uses quantum non-locality and uses quantum non-locality (quantum entanglement) to send information to the past. This is also the method used by Gaia's hometown."

The so-called non-locality of quantum is the characteristic of two quantums in an entangled state that communicate across regions. It is a manifestation of the quantum entangled state. No matter how far they are, two quantums in an entangled state, as long as one quantum changes in state, the other entangled quantum will inevitably change accordingly. This change is instantaneous, ignoring the information transmission of distance. Some people think that it exceeds the speed of light transmission and think that it cannot exist, but in fact this phenomenon does exist.

It’s like a and b are mother and daughter. Daughter B gave birth to a child in the United States. When B became a mother, A, who was far away in China, was immediately upgraded to grandma. In this regard, there is no need to call B to become grandma before she becomes grandma, but instantaneous.

"If a quantum a and quantum b in an entangled state, if a is on the earth and b is on the moon, when a man-made change of a state, b on the moon will also make corresponding changes at the same time. Their information propagation exceeds the speed of light."

"Through this principle, we have the conditions to send information to the past, which is to break the causality of events in the quantum field..."

"Send information to the past, is this possible?"

Su Yuan's face was full of disbelief. No matter how information communication is, the time for receiving the information is later than the time for sending it. Isn't it received it first and then sent it?

In her traditional consciousness, there seems to be no means to do this at all.

"No, this can be done."

This time, Xia Linfei did not reject Gao Jun's idea, but expressed his agreement.
Chapter completed!