Sending information to the past through quantum means.

From the perspective of spatio-temporal order, the information is received first, and then the information is sent, and this kind of event with effect and then cause is actually a kind of causal destruction in the spatio-temporal structure. This seemingly impossible thing is exactly what is being studied in the contemporary quantum field, and by all indications, it is achievable.

Subverting the causality of events with quantum means, first there is effect, then there is cause, this is definitely a crazy idea.

If everything is in the same world line, it is reluctantly acceptable because of the fixation of history.

……

……

"Su Yuan, you probably remember the double-slit interference experiment in high school. ”

Gao Jun suddenly spoke.

Su Yuan nodded and replied: "Remember, when the water waves pass through the double slit, there will be interference, and when it extends to the microscopic realm, it is also conclusive evidence to explain the 'wave-particle duality'. ”

Microscopic particles have both wave and particle properties, but two seemingly contradictory properties are actually present at the same time.

Gao Jun glanced at Xia Lin, Xia Linfeng picked up the eraser and erased all the graphics and words on the blackboard, she said: "Next, I will show you and Ye Hao an experimental idea with Gao Jun, and tell you whether quantum can replace cause and effect through it." ”

"How is the experiment done?"

A hint of curiosity flashed in Su Yuan's eyes.

Gao Jun smiled: "This experiment is mainly divided into five thinking steps!"

As he spoke, he drew two vertical lines on the blackboard, and wiped a point in the center of the previous one with his hand, causing a hole in it.

(1), you see. Now there is a slit bezel with a screen behind the bezel. Suppose a large number of small marbles are thrown from the front of the bezel, and the small marbles leave a mark on the screen through the gap in the bezel. Then the trail left should be a strip, right?"

Su Yuan nodded, "That's right, the macroscopic small particles can only move in a straight line after passing through the gap in the baffle, and it is a wide band on the screen behind them." ”

Gao Jun then wiped it again on the vertical line of the baffle, turning it into two holes.

"Now there are two seams, or are there a lot of small marbles thrown, are there two parallel bands left on the screen behind them?"

"Yes. ”

"So let's say we don't throw a lot of small marbles, and what goes towards the baffle is a macroscopic wave of water. Then when passing through a single slit, it should leave a bright stripe on the screen. ”

Su Yuan understood what Gao Jun meant, and simply took the initiative to say: "If there is a double slit on the baffle, then when the water waves pass through the baffle, a superposition of ripples will be formed behind the baffle, thus forming an interference phenomenon, leaving parallel stripes on the screen. ”

"That's right, this is a macroscopic interference experiment!"

Charlene said at this time: "Now for the second step. ”

(2), suppose that it is not a large number of small marbles that are now passing through the single-slit baffle. It's an infinite number of electrons on the microscopic scale, so what does it leave on the screen?"

"A single bright stripe!" Ji Ye Hao said in a determined tone.

Charlene nodded, "Yes, when a large number of microscopic electrons pass through a slit. will leave a bright stripe on the screen on the back. ”

"But what if you replace a single seam with a double seam?"

"A large number of microscopic electrons pass through the double slit, forming bright ripples similar to those caused by water wave interference. ”

Su Yuan replied confidently that the collective departure of a large number of electrons would form an interference phenomenon like water waves. This is the wave nature of microscopic particles.

Gao Jun asked, "Then do you think that a large number of electrons set off collectively after passing through two slits." What causes them to interfere?"

"Maybe it's the ...... between the electrons," Charlene smiled and gave a guess.

Gao Jun nodded, "Perhaps this phenomenon can be explained by the interaction between groups. So let's move on to the next step. ”

“（3）。 Don't let a large number of electrons pass through, but release them one by one, only one microscopic electron at a time, so that they don't interfere with each other. ”

"What will be the result of this?" Su Yuan was a little curious, in the double-slit interference experiment of electrons, he really didn't talk about what kind of results would be caused by using this experimental method.

"As the experiment progressed, after releasing enough electrons in turn, the experimenters found that rows of interfering streaks appeared on the screen behind the double slit again, and the results were exactly the same as if a large number of electrons were being released at the same time. ”

"Why is this happening? Isn't the interaction between electrons ruled out?"

Such a result is indeed incomprehensible. Although Su Yuan knew that most of the results would be like this, why did this happen?

"It stands to reason that only one electron is released at a time, and the electron either passes through the 1st slit or the 2nd slit, and if only one of the slits passes through, then it is the same effect as the single-slit experiment in step (2), which should leave two clear stripes, but in fact it is the effect of double-slit interference. ”

"The only explanation is that when a single electron approaches a double slit, it knows that there is a double slit in front, so it splits in two, half through slit 1 and half through slit 2, and interferes with each other after passing, and then merges into one and leaves a mark on the screen. ”

"But this is mathematically inexplicable, it passes through two seams at the same time, and not chooses one of them!"

Charlene said, "So scientists have to figure out which one it went through! ”

(4), two detection devices are installed on both sides of the rear of the two seams to monitor the state of electrons when they pass through the gaps. When an electron passes through the No. 1 slit, the detector on the same side as it will give an alarm. The purpose of this experiment is to determine what route a single electron takes when passing through the double slit, and whether it is possible to pass through both slits at the same time. Our experimental thinking has already considered electrons as macroscopic particles, but what we are actually looking at is particle. ”

"What was the result?" asked Su Yuan.

"By releasing one electron at a time, repeated experiments have revealed that the electrons pass through the slits one by one. Two bright stripes appear on the screen, and there is not a single ripple that interferes. ”

Ji Ye Hao said unexpectedly: "It's just that detectors are installed on both sides of the gap." It doesn't affect the path of the electrons, but the result becomes the same as that of a macroscopic particle?"

In step (4). The wave-like nature of microscopic particles disappears, and instead they appear as granular properties as macroscopic particles!

"Yes, we just want to see which slit the electron passes through, to determine if it is possible to pass through both slits at the same time, the experimental thinking is based on particle, and the result is that the electron seems to know that we are observing it, and does not show wave at all. ”

"Electronics are fine!"

Su Yuan frowned and joked.

"Then I'm going to move on to the fifth step. ”

(5), if it is still the same as step (4). As long as the detector does not alarm, humans will not know which slit it has passed, and there is no premise of preset particle, and under such conditions, the experiment of step (4) continues. ”

In fact, the experimental equipment of the experiment (5) and the experiment (4) are exactly the same, and the difference is whether the alarm is used to let humans know the path of the particles.

"What is the result? Will it still show granularity like (4)?" asked Ji Ye Hao.

Su Yuan shook his head, "Since Gao Jun and Sister Xia have given this example, the result is definitely not the same!"

Gao Jun said: "Su Yuan is right. The experimental result of step (5) is indeed different from that of (4), and the experimental result is that rows of interference fringes appear again on the rear screen, showing volatility. ”

"So why is that, why is it that humans can't know its path of movement in the first place? The only difference between the experiment in step (5) and step (4) is whether we know the trajectory of the electron. But if we know the electron trajectory, will it affect the results of the experiment?"

This is really a question that makes people think deeply.

We don't want to see particles, and we design experiments based on this (5). It ends up showing interference fringes in front of us, showing volatility.

We designed the experiment with particle thinking (4). An alarm function has been added, but it behaves as particles.

Other words. The purpose of our experiments, and the experiments designed for this purpose, led to the emergence of results that matched them.

Ji Ye Hao wrinkled his brows and said, "If you have to explain it with a theory, this is probably the 'observer effect'. ”

Gao Jun agreed: "Yes, in quantum theory, particles are in a superposition state or wave function with multiple possibilities, and according to the wave packet collapse effect of the Copenhagen School, when an observer observes it, the superposition state will collapse into a fixed state to be observed, which is the 'observer effect'." ”

"But what does this have to do with causality?"

Su Yuan thought of the purpose of the experiment at the beginning, Gao Jun and Xia Linfeng aimed to tell the reversal of cause and effect through this experiment.

"Don't worry. ”

Xia Linfang looked at her with a smile and said to Gao Jun, "You come and tell everyone." ”

Gao Jun nodded and said: "In the above experiment, since the whole process is the release of a single electron and a single electron, when showing wave nature, the electron obviously passes through two slits at the same time and has two paths, so self-interference occurs; ”

In other words, after passing through the first vertical line with two notches, the electron itself has already chosen a way to pass through, either through two slits at the same time, choosing two paths, showing wave, or only passing through one slit, choosing a path, showing particle. ”

"The reference for this choice depends on knowing in advance what properties we want to observe it. ”

"So let's stretch it a little bit, let's say we design an experiment where we suddenly change the properties we want to observe when an electron passes through a vertical line on a separator, but before it reaches the screen. ”

"For example, if the original experimental condition is that no alarm device is added as in step (5), indicating that we do not emphasize particle, then according to step (5), the electron should make a choice when passing through the double slit and pass through both slits at the same time. And when the electrons have made a choice to pass through the two gaps but have not yet reached the detector, we suddenly add an alarm device artificially and quickly, indicating that we have changed our minds and now want to see the particle properties of the electrons. ”

"As a result, only a one-sided alarm reacted, and after trial and error, it showed a particle-like streak on the screen. ”

"What does this mean, in chronological order, the electrons make the choice first to show volatility, and the electrons split in two and pass through the double slit. However, due to the artificial change of the measurement target, the electrons that have passed through the double slit have only passed through a thin slit ......"

This suggests that after we have made our choice, the electrons that have identified the path have changed.

Cause and effect are altered on a small scale, and we "observe" the electron, resulting in a change in the "past history" of the electron.

On the other hand, the choice of the present can change not only the future, but also the past. Time and space are continuous, and any little action on the timeline may affect the development of events in the entire time and space! Based on this, it is only necessary to increase the amount of causal displacement on the timeline to create the prototype of a time machine. (To be continued......)

PS: This chapter is more difficult to understand, everyone read it carefully!!