A Man of Science and Engineering in Troubled Times Wandering in the Late Qing Dynasty

Chapter 707 Don’t Tell God What to Do

The formal meeting will not start until tomorrow, so today we are just getting together to have a meal and chat.

Bohr hadn't seen Dirac for a while, so he asked casually, "What research are you doing?"

“I am trying to find a quantum theory of the electron that is consistent with relativity,” Dirac said.

Bohr was puzzled: "Hasn't Klein solved this problem?"

The Klein that Bohr mentioned was the Swedish theorist Oscar Klein. The Klein-Nishina formula that Millikan asked Zhao Zhongyao to verify was also from him.

“Klein’s equations still have many flaws,” said Dirac, who was well qualified to comment on this field, “because according to his equations, the probability of detecting an electron in a tiny range of space and time is sometimes less than zero. It obviously needs further improvement.”

Bohr said: "I hope you can succeed, so that you can have greater theoretical support to refute those who oppose quantum theory."

Li Yu smiled and said, "In fact, everyone has accepted quantum, but what they cannot accept is probability."

The food provided at this conference was good, mainly French cuisine, and there was also Belgian beer.

Pauli, having had a full meal, sat on the sofa, lit a cigarette, took a puff, and then said, "I think Mr. Einstein couldn't accept probability because he was afraid of recreating Newton's first impulse and letting theology enter the field of science."

Three hundred years ago, after Newton proposed the law of universal gravitation and the three laws of mechanics, there was still a problem that could not be solved: what force makes the planets move from a standstill?

Out of desperation, Newton put forward the idea of ​​"God's first mover".

Of course, this statement was later proven to be wrong.

Probability is very useful in mathematics, but physics is physics after all. If probability exists at such a deep core of its essence, it would be really hard for professional giants like Einstein to believe it.

And it is indeed an excellent angle that can be easily seized by theologians to attack science.

——It turns out that, apart from the debates between experts in their fields, Pauli overestimated the scientific literacy of others. But it is a hidden danger anyway.

Li Yu said: "Einstein always liked to use God as an analogy when discussing basic physics."

"Yes," Bohr could well testify, "he told me several times that God doesn't like to play dice."

This is a quote often used by Einstein to attack the probabilistic interpretation of quantum mechanics.

Pauli joked: "No one should play cards with God."

"I don't think this has anything to do with religion," Dirac said suddenly. "Religion is just a bunch of false assertions that don't hold up in reality. The concept of God is a product of human imagination, and the hypothetical omnipotent God is useless and unnecessary. Teaching people to believe in God is just because some people want to keep the lower classes silent."

Pauli laughed and said, "The lower class? Dirac, there is a bit of red thought in your words."

Dirac did have this tendency, as did Oppenheimer mentioned earlier. Both of them had a good relationship with Kapitsa, and I wonder if they were influenced by him.

“I don’t think there’s anything wrong with red ideology,” Dirac said.

At this time, believing in red was quite common and normal in Europe.

"That's true," Heisenberg said, "but I disagree with your statement about religion. In my opinion, most things in this world can be misinterpreted and abused, but they can also be used for good."

Dirac was a staunch anti-religious person. He replied, “But I dislike religious fairy tales fabricated to promote religious beliefs. Whether an idea is correct depends on the individual’s independent judgment. Those religious fairy tales have trapped mankind for too many years. Everyone should be given the right to make independent judgments, rather than continue to be indoctrinated with hypocritical fairy tales.”

Heisenberg poked Pauli: "What are you thinking about?"

Pauli said: "Our friend Dirac also has his own religion."

Dirac said: "I don't believe in God, I believe in science."

Pauli laughed out loud: "Don't be ridiculous, you are God!"

Then everyone started laughing together.

The next day, Li Yu gave the opening report for the formal meeting. Although he had a good relationship with Einstein, this time Li Yu had to stand on the side of Copenhagen.

"According to current theories and experimental evidence, determinism and strict causality do not exist at the subatomic level. There are no deterministic laws, only probabilities and contingencies. Therefore, it is meaningless to talk about 'reality' apart from observation and measurement. Depending on the type of experiment chosen, light can be either a wave or a particle."

After a concise summary, several people gave their reports in turn.

According to the arrangement of the meeting, experimentalists Compton and Bragg would first talk about the recent experimental progress.

The next person to give the report was de Broglie, after all, his doctoral thesis opened the new quantum era.

But de Broglie had already stood in Einstein's camp. After explaining the theory of matter waves, he actually proposed a very strange theory:

“I came up with a theory that can abandon the probabilistic interpretation of the Schrödinger equation, which I will call the pilot wave model.

"In this model, an electron consists of two interrelated, physically real entities: a wave and a particle, and the particle rides the wave like a surfer..."

De Broglie's statement is obviously far-fetched.

While the others were still listening, Pauli was the first to get impatient and asked, "If matter moves on waves, when does it stop, when does it move forward, and when does it move backward?"

This question was so fatal that de Broglie was instantly stumped. He felt that there was no need to continue, so he said: "It is still a hypothesis and is not particularly perfect."

Pauli was straightforward: "Great, you don't have to waste any more time. No one here wants to hear how history is reversed."

De Broglie was left speechless by Pauli's rebuttal.

Round.1, De Broglie was defeated.

The host Lorentz then said: "The next speakers are Professors Heisenberg and Born."

They must still be talking about matrix mechanics. At the end, Heisenberg solemnly said a very crucial sentence:

"We argue that quantum mechanics is a complete theory and that its basic physical and mathematical assumptions do not require further modification."

Einstein, who remained silent in the audience, immediately picked up the pen and wrote it down in the small notebook in his hand, but still did not speak.

Bohr led the applause.

The next person to report after Heisenberg was Schrödinger.

He spoke of wave mechanics and his own Schrödinger equation as usual, and then tried to win back a point for de Broglie, pointing directly at Heisenberg at the end of his report:

"From Professor Heisenberg's report, I found that he did not agree with my 'electron cloud' view. But according to the current situation, we can only acknowledge the existence of electron clouds and acknowledge that electrons do spread out in space like waves."

Heisenberg was clearly prepared: "This view is untenable! And I don't see anything in Professor Schrödinger's calculations that proves that the facts are as he hopes." Schrödinger frowned: "My calculations are indeed a little unsatisfactory, but talking about the orbits of electrons is pure nonsense. It should be a superposition of wave eigenstates."

Heisenberg shot back, "No, that's not bullshit at all!"

The two continued to argue.

However, no conclusion was reached because the issue of electrons is too complicated. Not to mention now, even a hundred years later, the scientific community has not fully understood the nature of electrons.

Round.2, it’s a draw.

Born looked at Einstein and asked, "Mr. Einstein, you seem to have said nothing."

Einstein coughed slightly and said, "I'm sorry, I didn't study quantum mechanics deeply enough."

Born said: "If you want to study the grand unified theory, you can't avoid quantum theory."

Einstein said: "But I do not want to work on a theory which is constructed of a host of 'perhaps' and which is ultimately wrong, even though it may be empirically and logically correct."

Heisenberg immediately refused: "Probability is the most profound interpretation."

……

The first day of exchanges ended in an argument, which continued after dinner at the Brittany Hotel where everyone stayed, near today's European Parliament office building.

That night, the Copenhagen group held a secret meeting.

"Einstein spoke so little and made such a decisive judgment in the end. He must have had no good intentions!" said Pauli.

Li Yu laughed and said, "No good intentions? The word you use is..."

"Very appropriate!" Pauli said. "I think he will strike back tomorrow."

Bohr was at ease: "I haven't talked about my principle of complementarity yet. At that time, in conjunction with Heisenberg's uncertainty principle, Einstein could continue to remain silent."

Heisenberg was quite confident in this explanation: "Even if they don't admit it, we have to admit it."

The next day, the report was still normal.

Bohr brought out the principle of complementarity that he had just realized.

Sure enough, Einstein in the audience was taking notes again.

After Bohr finished speaking, Lorentz looked at Einstein and said, "I know you have a lot to say."

"Thank you."

Einstein walked to the stage with great confidence and first drew a picture of the diffraction image formed by an electron passing through a small hole. This experiment had been confirmed.

He went on to say:
"I have listened to all the reports in full. To summarize briefly, there are two views now.
“The first view is that of Professors de Broglie and Schrödinger, who believed that matter waves are real, so electrons can be seen as electron clouds that permeate the air;

"The second view is the probability explanation supported by Heisenberg, Li Yu, Bohr, Born and others, which holds that waves only describe the probability of the position of particles in space, that is, there is only one electron, but its position cannot be determined.

“Obviously, the second view encompasses the first.

"But! I think the second one is wrong.

“Physics should not be uncertain because this randomness states that the same process can produce many different outcomes.

"For example, when an electron is emitted toward a screen, its position in space is uncertain before it reaches the screen. But once the electron reaches the screen, the wave function collapses and the position is determined. The probability of the electron receiving point instantly becomes 100%, and the probability of other positions instantly becomes 0.

"What is this? This is action at a distance, which violates the theory of relativity!"

Although Pauli had long guessed that Einstein had some "dirty tricks", he did not expect that his tricks were so brilliant.

The meeting place suddenly fell into silence.

After a while, Li Yu said, "The microcosm is different from the macrocosm. In the microcosm, the position of particles in space is probabilistically distributed and uncertain. But once measured, its position is determined. So the screen itself is a means of measurement."

Einstein stroked his chin and said, "Let's just assume so."

There was no doubt in his tone that he was not convinced at all.

Heisenberg knew that what Einstein wanted to attack most was the uncertainty principle, which was one of the quantum theories that he could not accept the most. So he said: "The uncertainty principle is based on very rigorous mathematical derivation, and the physical basis used is all from observable measurements, which is completely tenable."

Einstein retorted: “But you do not seriously believe that nothing besides observables can appear in a physical theory?”

Heisenberg seemed to have guessed what Einstein would say and quickly hit back: "In your theory of relativity, you also exclude concepts such as absolute space and absolute time because they are unobservable."

Einstein's eye twitched, and after thinking for a moment, he said, "But in my theory of relativity, God does not play dice! The uncertainty assumption violates the most basic law of causality."

Bohr smiled and said, "Mr. Einstein, we talked about the issue of God on the first day, so please don't tell God what to do anymore."

Li Yu listened to their heated debate and casually wrote a line of words on the blackboard: "God really confused people's language!"

When everyone in the audience saw this line of words, they all laughed out loud.

This story is quite famous and comes from a Western fable:

Legend has it that the ancestors of mankind originally spoke the same language. They found a very fertile land, so they settled down there and built a city. Later, they decided to build a high tower that could reach the sky. This is the Tower of Babel (also known as the Tower of Babylon).

They used bricks and river mud as building materials, worked together in unity, and the project progressed smoothly. The tower continued to grow higher until the top of the tower reached the sky.

When God heard about this, he immediately came down to earth to inspect. He was a little panicked, thinking that if humans worked together, nothing in the world could stump them.

At the same time, God was also very angry and thought this was a symbol of human vanity.

So God scattered mankind all over the world and decided to confuse the world's languages ​​so that they could not communicate and understand each other. Later, people called Babylon "the city that offended God."

Dirac, who had been silent the whole time, smiled and said, “It turns out that God has already told humans what to do.”

Einstein said slowly: "The old man is so bad!"

Although he often used God as a metaphor, most of the time afterwards, he used the term "old man" to refer to God.

And this God is obviously not the God in religion, but just a metaphor.

(End of this chapter)