Chapter 10 Chapter 8 Controversy-1

one The city of Como (Como) in northern Italy is a beautiful small city, facing the scenic Lake Como in the north, not far from Milan.The famous churches in the city center are full of Gothic style and Renaissance atmosphere, reflecting the country's long history and cultural heritage.This small town also has a football team - the Como team, which also entered the first division last season (2002-2003), but it is a pity that it has been relegated now.It was once reported that it was interested in the Chinese player Wu Chengying, and it was not unfamiliar to the fans. However, the most famous person in Como is of course the great scientist born here in 1745, Alessandro Volta (Alessandro Volta).His achievements in electricity are so great that people use his name as a unit of voltage: volt (volt).Volta died in September 1827, and was regarded as eternal glory and pride by his hometown.The place where he was born was named Volta Square, where his statue has stood since 1839.His name was used for the church and the lighthouse on Lake Como, and his light illuminated the town and brought it worldwide fame.

In the blink of an eye, it is already 1927, and it has been 100 years since the giant of science left us.Como, which has always been quiet and quiet, suddenly became lively again, and the masters of science in the new era gathered here again to discuss the latest developments in physics while commemorating their ancestors.The Como meeting invited almost all the most outstanding physicists at that time, and it was a grand event.Attendees included Bohr, Heisenberg, Planck, Pauli, Bonn, Lorenz, de Broglie, Fermi, Kramer, Laue, Compton, Wegener, Sommerfeld , Debye, von Neumann (of course, strictly speaking, this person is a mathematician)... Unfortunately, Einstein and Schrödinger were unable to attend due to other important business.The absence of the two main rivals of the Copenhagen faction delayed the spark of the debate by several months.Dirac and Bose also failed to make it to Como.Among them, the case of Bose is quite bizarre: he was originally invited to the conference, but the invitation letter was sent to "Professor Bose of the Department of Physics, University of Calcutta".Obviously this letter was sent to the famous SN Bose, that is, the Bose who discovered the Bose-Einstein statistics, and he and Einstein also predicted the famous Bose-Einstein condensation phenomenon. In 2001, three scientists from the United States and Germany won the Nobel Prize in Physics for their experimental confirmation of this phenomenon.

In 1927, however, Bose had long since left Calcutta for the University of Dhaka.But coincidentally, Calcutta also has a DM Bose.By accident, this little-known "Bose" participated in the star-studded Como meeting, which can be regarded as a big talk after the meal. In the process of preparing the speeches for the Como Conference, the idea of ​​the principle of complementarity was further formed in Bohr's mind.He decided to reveal this bold thought at this meeting.While preparing the speech, he also wrote a short article for the journal Nature to introduce this discovery. There were too many things and the time was short, which finally made him in a hurry.Moments before departure, he couldn't find his passport - which delayed the train for hours.

However, no matter what, Bohr finally completed the 8-page speech and successfully delivered a speech at the conference.The lecture was entitled "Quantum Postulates and Recent Developments in Atomic Theory", in which Bohr described the wave-particle duality for the first time, using the principle of complementarity to elaborate our attitude towards the atomic-scale world.He emphasized the importance of observation, claiming that completely independent and absolute measurements do not exist.Of course, the principle of complementarity itself has not been fully finalized at this time, and it was not finally completed until the later Solvay Conference, but this idea has now attracted people's attention.

Born praised Bohr's "pertinent" point of view, while emphasizing the uncertainty of quantum theory.He specifically cited the example of wave function "collapse" to illustrate this point.This "collapse" apparently intrigued von Neumann, who later demonstrated some interesting properties about it.Heisenberg and Kramer et al. also commented. Of course, we must also point out that many people who do not belong to the "Copenhagen School" are not familiar with the ideas and work of Bohr and others. This principle of complementarity is puzzling to them.Many people think that this is just a word game, a "rephrasing" of a situation that everyone knows.As Rosenfeld later commented on the talk show: "This principle of complementarity is just an illustration of what everyone knows...the Cuomo conference did not have clear arguments, and the definition of the concept was not made until later. ’” Eugene Wigner concluded: “… [Bohr’s lecture, it was felt,] did not change anyone’s way of understanding quantum theory.”

However, the historical role of the Cuomo meeting should not be underestimated. The first public appearance of the principle of complementarity marked a crucial step in the Copenhagen Interpretation.Bohr's lectures were published shortly thereafter, and the content has been improved, and the final maturity of this explanation is only the last step. While the Copenhagenists gathered strength, their opposition began to prepare for the final showdown.For Einstein, a physical world without strict causal laws was unthinkable.The laws of physics should rule, and physics should be simple and clear: A caused B, B caused C, and C caused D.Every event has its ins and outs, causes and results, and does not depend on any "randomness".As for abandoning objective reality, it is even more inconceivable.These ideas have already emerged from his views on Bohr's electronic transition. In 1924 he insisted in a letter to Bonn: "I am by no means willing to be forced to abandon strict causality, and will defend it vigorously. I find it absolutely intolerable that the idea that electrons are irradiated Irradiation, not only its moment of transition, but also its direction of transition, is chosen by its own 'free will'."

The old quantum theory has already made Einstein unable to agree, so the more "crazy" new quantum theory made him intolerable.Although Einstein himself once put forward the light quantum hypothesis and made indelible contributions in the development of quantum theory, now he has completely turned to the opposite of this nascent theory.Einstein firmly believed that the foundation of quantum theory was very flawed, and that some thorns would be picked out from it, forcing people to return to a strict, causal theory.Bohr later recalled: "Einstein was the best at not abandoning continuity and causality to label seemingly contradictory experiences. He was more reluctant than others to abandon these concepts."

The two giants failed to meet at the Cuomo meeting, but they looked down and did not see each other. Fate has already arranged such a meeting is inevitable.Just over a month later, another historic moment came when the 5th Solvay Conference was held in Brussels, Belgium.This time, enemies from all walks of life finally gathered together to have a decisive battle on the issue of quantum theory.The old man who came from the golden age, the rebellious youth who grew up in the wave of revolution, the solemn guardian of the classic system, and the adventurer of the new era all have to make a final decision this time.The prelude to the great debate of the century is about to kick off, burning like a raging fire, and quantum theory will also undergo the most severe baptism in this fire, forging a brighter light.

See you in Brussels. *********** Gossip after dinner: Heisenberg and the German atomic bomb program (1) If the Bohr-Einstein debate is the most famous debate in the history of science in the twentieth century, then the role of Heisenberg in World War II is probably the biggest mystery in the history of science in the twentieth century.I don’t know how many historians have spent their mouths on this, and it has involved countless cross-border controversies.Even now, there are still people who continue to raise objections.I plan to talk about this topic in the after-dinner gossip in this chapter. This is a long story, and it may take up a whole chapter. Let's cut the nonsense, and let's start.

Why didn't Nazi Germany build an atomic bomb?Almost everyone was asking that question after the war.Is it a policy reason?Theoretical reasons?Technical reasons?Resource reasons?Or moral reasons?Yes, the United States built the atomic bomb. They had Oppenheimer, Fermi, Lawrence, Bate, Seaberg, Wegener, Chadwick, Perls, Frisch, Segre, and later With Bohr again, juniors like Feynman are inconspicuous at all, and Los Alamos is also known as "the concentration camp of Nobel Prize winners."But Germany is not bad at all.Yes, Hitler’s Jewish policy drove away almost half of the domestic elite. In the first year when the Nazis came to power, about 2,600 scholars left Germany, and a quarter of physicists resigned from German universities. Already on the eve of the war 40% of university professors had lost their jobs.Yes, the entire Axis lost as many as 27 Nobel Prize winners, including even the most prominent such as Einstein, Schrödinger, Fermi, Born, Pauli, Debye, and this number is not counting indirect losses like Bohr.But Germany still retains the ability to fight against the whole world with its amazing strength.

As soon as the war broke out, Germany launched a research program for the atomic bomb.It was 1939, and only one company in the world, Germany, was carrying out such a military application project of atomic energy.Germany occupies the world's largest uranium mine (in Czechoslovakia), Germany has the world's most powerful chemical industry, they still have the world's best scientists, the phenomenon of atomic fission is two Germans - Otto? Hahn (Otto Hahn and Fritz Strassmann, both still in Germany, the year before, for which Hahn would later win the Nobel Prize in Chemistry.Of course, not only these two people, Germany also has Laue (Nobel Physics in 1914), Porter (Bothe, Nobel Physics in 1954), Geiger (the inventor of the Geiger counter, he carried out the α scattering experiment), Weizak (Karl von Weizsacker), Bagge (Erich Bagge), Diebner (Kurt Diebner), Gerlach (Walther Gerlach), Woz (Karl Wirtz)... Of course, they also have Heisenberg, the 20th century One of the greatest physicists.All of these scientists participated in Hitler's atomic bomb program and became members of the "Uranium Club", of which Heisenberg was the general manager. However, Germany failed to build the atomic bomb, it didn't even have access to it.From 1942 onwards, Germany seems to have abandoned the entire atomic bomb program, and instead studied the construction of a nuclear reactor that could provide energy.The main reason is that in June 1942, Heisenberg sent Arms Minister Albert Speer Speer reported that the uranium program was difficult to produce any real results in a short period of time for technical reasons, and that an atomic bomb during the war was unlikely.But he also convinced Speer that German research was still ahead.Speer reported this situation to Hitler. At that time, due to the urgency of the entire battlefield situation, Germany's research plan was forced to adopt a quick success strategy, that is, plans that could not be effective in a short time, to be precise, within six weeks were all rejected. Set aside for now.Hitler and Speer reached an agreement: there is no need to spend too much effort on the atomic bomb, but since it is still "leading" in this area, it may as well continue to allocate funds for research.At that time, Heisenberg applied for an additional budget of only 350,000 Reichsmarks, and it would have little effect with or without it. After being let go by the top for nearly two years, this plan was finally noticed by Himmler in 1944.He ordered massive funding to push the atomic bomb program forward and built several new uranium plants.The plan did make progress, but by that time, the entire German industry had been shattered by Allied bombing and it was difficult to sustain it any further.And it was too late, as Germany surrendered soon after. What happened to the 1942 report?What role did Heisenberg play in it?The answer is complicated and confusing, and historians insist on their own opinions. If it were not for the disclosure of new evidence one by one, I am afraid that people are still in the fog.This is the famous "Heisenberg's mystery" in the history of science. two The Solvay meeting was initiated by a Belgian industrialist Ernest Solvay founded and bears his name.The first Solvay Conference was held in Brussels in 1911. Although it was interrupted by the First World War, it resumed in 1921 and was held every three years.By 1927, this was already the fifth Solvay Conference, and perhaps, it would also be the most famous Solvay Conference. This meeting made up for Cuomo's regret, and Einstein, Schrödinger and others all came as scheduled.The most widely circulated photo of the "Physics All-Star Dream Team" is a group photo of this meeting.Of course, nothing is perfect in this world, and if we insist on picking some flaws, Sommerfeld and Jordan are not among them. However, our requirements should not be too high, and there are still nine out of ten people who are unsatisfactory in life. The conference will last for 6 days from October 24th to 29th.The theme is "Electrons and Photons" (we still remember that "photon-photon" is a new term, which was just proposed by the American Lewis in 1926), and the agenda of the meeting is as follows: First, Lawrence Bragg made an experimental report on X-rays, Compton then reported on Compton's experiments and their inconsistencies with classical electromagnetic theory.Next, de Broglie gave a lecture on the new quantum mechanics, mainly about de Broglie waves of particles.Then Born and Heisenberg introduced the matrix theory of quantum mechanics, while Schrödinger introduced wave mechanics.Finally, on the basis of Como's speech, Bohr made another report on the quantum postulate and the new theory of atoms, further summarizing the principle of complementarity, and laying the entire philosophical foundation for quantum theory.The agenda itself is nothing short of a miniature history of quantum theory, from which three distinct factions can be distinguished: the experimental faction, concerned only with experimental results: Prague and Compton; the Copenhagen faction: Bohr, Bonn, and Heisenberg; and Copenhagen Pi's sworn enemies: De Broglie, Schrödinger, and Einstein in the audience. The atmosphere of the meeting was hot from the very beginning, just like a boxing championship match, before the main event came a series of preliminary matches: everyone discussed Compton's experiment first, and then everyone was divided into distinct camps, each other shelled.De Broglie took the lead in making a speech. He tried to integrate particles into the wave image, and proposed a "guided wave" (pivot wave) theory, that the particle is a singularity of the wave equation, it must be controlled and guided by the wave.Pauli stood up and criticized this theory fiercely. First of all, he could not tolerate the turning of the wheel of history and returning to a traditional image, and then he cited a series of experimental results to refute de Broglie.As we all know, Pauli is the world's number one sniper, and whoever is targeted by him will probably end badly. De Broglie had to publicly renounce his point of view in the end.Fortunately, Schrödinger came to help, but he still insisted on a very traditional explanation, which even the Allied Army De Broglie was not satisfied with. Pauli had long ridiculed Schrödinger as "naive".Bonn and Heisenberg hid behind the Copenhagen bunker and opened fire on it. At the end of their report, they said: "We maintain that quantum mechanics is a complete theory, and its basic physical and mathematical assumptions cannot be further modified." They It also focused heavily on Schrödinger's "electron cloud", which argued that electrons did indeed spread out in space like waves.Heisenberg commented: "I don't see anything from Schrödinger's calculations to prove that the facts are as he hoped." Schrödinger admitted that his calculations were indeed not satisfactory, but he still insisted, talking about the orbit of the electron It is "nonsense" (should be the superposition of Bourbon's eigenstate), Bonn replied: "No, it is not nonsense at all." In the smoke, the organizer of the meeting, the veteran Lorenz also published some conservative Viewpoint, and so on and so on... At first Einstein held back, keeping an eerie silence, but when Born mentioned his name, he finally couldn't help but strike.He proposed a model: An electron passes through a small hole to obtain a diffraction image.Einstein pointed out that there are currently two viewpoints. The first is that there is no "one electron", but only "a cloud of electrons", which is a reality in space, described by de Broglie-Schrödinger waves.The second is that there is indeed an electron, and ψ is its "probability distribution". The electron itself does not diffuse into the air, but its probability wave.Einstein conceded that Viewpoint II is more complete than Viewpoint I because it encompasses Viewpoint I in its entirety.Still, Einstein said, he had to object to View II.Because this randomness suggests that the same process can produce many different outcomes, and that many areas of the sensing screen respond simultaneously to the observations of the electrons, it seems to suggest an action at a distance, thus contradicting the relativity. The situation is changing, dragons and tigers are fighting each other, and now the masters behind the scenes of the two camps have finally come to the stage to start a fate-determining duel.It is a pity that there are no official records of the original discussion records of Bohr and others, and the reconstruction of the scene at that time mainly relies on the memories of several parties involved.Among them is the long article "Discussion with Einstein on Epistemological Issues in Atomic Physics" that Bohr himself was invited to write to celebrate Einstein's 70th birthday in 1949, and Heisenberg, de Broglie and Memories and letters of Ehrenfest, etc.At that time, there was a fierce battle, and the problem discussed was the dilemma of the electron in front of the double slit that we have already described: how to choose its path and the effect of closing/opening a slit quickly on the electron.There are many, many other thought experiments.Ehrenfest described in a letter to his disciples (Uhlenbert and Gudschmidt, etc.) who stayed in Leiden: Einstein is like a spring doll, bringing a new one every morning. Ideas popped out of the box, and Bohr found tools in the cloud of philosophy to crush all the arguments of the other party. Heisenberg recalled in 1967: "The discussion quickly turned into a duel between Einstein and Bohr: how far could the atomic theory of the time be seen as the final answer to the difficulties that had been discussed for decades? We met over breakfast, and Einstein described a thought experiment in which he thought the internal contradictions of the Copenhagen interpretation could be clearly seen. Then Einstein, Bohr, and I walked to the venue together, and I could Listening to the discussions of these two people with very different philosophical attitudes, I often insert a few words on the structure of mathematical expressions. In the middle of the meeting, especially during the break, we young people-mostly me and Pa Leigh—just tried to analyze Einstein's experiments, and the discussion at lunch was between Bohr and other people from Copenhagen. Generally speaking, Bohr fully understood these ideal experiments in the evening. Knowing it well, he would analyze them to Einstein at dinner. Einstein could not refute the analysis, but in his heart he was not convinced." Einstein, of course, was not convinced. He believed in the law of causality so devoutly that he could never believe the cynical probability explanation of Copenhagen.Bohr recalled that Einstein once asked him mockingly, did he really believe that the power of God depended on the throwing of dice (ob der liebe Gott wurfelt)? God doesn't play dice!This is not the first time Einstein has said this.Writing to Born as early as 1926, he said: "Quantum mechanics is impressive, but an inner voice tells me that it is not real. The theory has produced many good results, but it has not We are closer to the mystery of 'The Don'. I believe without reservation that the 'Don' doesn't roll the dice." "Old Man" was Einstein's nickname for God. However, in the Huashan debate in 1927, Einstein finally lost a move.It's not that he's not good at swordsmanship, it's that he lacks internal strength.Facing the mighty historical tide, he stubbornly went upstream, but was washed away so that he could not stand firmly and struggled to support. In 1927, the explosion of the quantum revolution had entered its third year, and it had reached a final stage.The seeds planted in the past are now bearing fruit, and the revolutionary trend of thought has swept the entire physics world, unreservedly pointing out the direction of the future.More and more people have finally realized the core esoteric meaning of Copenhagen's explanation, and sincerely converted, and cast themselves under the gate of quantum.Instead of convincing Bohr, Einstein was often refuted speechless, and his "reactionary" attitude caused many people to sigh.Back in the day, in 1905, Einstein was born out of nowhere, and he made six shots within a year, each of which was earth-shattering, shocking the world, and created a vigorous career by himself.At that time, the young man was full of spirit, looked down upon the heroes, whipped his horse, and smiled proudly. This legendary picture left an eternal fascination in the hearts of many people!However, Einstein, who was the most rebellious, revolutionary, informal, and contemptuous of authority back then, is now standing on the opposite side of the new quantum theory! "We have lost our leader," Bonn lamented. Ehrenfest said to Einstein angrily: "Einstein, I blush for you! You put yourself in the same position as those who try in vain to overthrow the theory of relativity." Einstein lost this battle embarrassingly, and Bohr looked silent and dull, but his epee had no edge, and there was no good luck. He almost never lost a serious debate in his life.The Copenhagen School and its interpretation of quantum theory won a big victory. Heisenberg said in a letter to his family: "I am very satisfied with the results. Bohr and my views are widely accepted, at least no one mentions them." Even Einstein and Schrödinger can’t come up with strict rebuttals.” Many years later he concluded: “At the beginning (holding this point of view) it was mainly Bohr, Pauli and me, probably only the three of us, but It spread quickly." But Einstein was not the kind of person who was easily defeated. He stood against the wind, his disheveled hair could not conceal the determination in his eyes.There are two people standing behind him, one is De Broglie and the other is Schrödinger.The three of them, Wu with Lingfeng and fluttering clothes, in the dawn of the quantum age, have a great sense of sadness, and the sad and heroic spirit of vowing to live and die with the classical theory. Time flies, another three years in a snap of the fingers, and the heroes from all sides reunited in Brussels to meet at the 6th Solvay Conference.The battle three years ago has become a thing of the past, and this second Huashan sword debate, who will win and who will lose? *********** Gossip after dinner: Heisenberg and the German atomic bomb program (2) In 1944, the Allied forces landed in Normandy, forming a two-sided attack.By April 1945, Nazi Germany was over, and the end of the fighting in Europe was imminent.The task before the Americans is now to collect as many remaining German scientists and equipment as possible, and prevent them from falling into the hands of other countries (neither the Soviet Union nor France).In a hopeless race against the Soviets to see who would capture Berlin first, they turned south and soon captured the scientists of the German uranium program, seizing most of the materials and equipment.But at that time, Heisenberg had already left early and fled back to his home in Urfeld, which was still in the hands of the Germans at the time. However, in order to get Heisenberg, the "first target", the Allied forces sent a small detachment. On May 3, four days after the Hitler couple committed suicide, they went to Heisenberg's home and caught him.The scientist behaved quite gracefully. He introduced his wife and children politely, and asked the American soldiers what they thought of the scenery in Germany.On May 7, Germany surrendered. Ten of Germany's most famous scientists were secretly sent to England and locked up in a house called "Farm Hall" near Cambridge.They didn't know that the house was bugged and that their conversations were taped and recorded. We will talk about these key records later. On the night of August 6, news of the atomic bombing of Hiroshima came, leaving everyone dumbfounded.We will talk about the details of that time later. After the war, these scientists were all released.But now both experts and the public are interested in why Germany failed to build the atomic bomb.With the usual pride of German scientists, it is absolutely unacceptable to admit that they are inferior to others.While still in prison, on the third day after Hiroshima, Heisenberg and others drafted a memorandum stating: 1. The phenomenon of atomic fission was discovered by Germans Hahn and Strassmann in 1938. 2. Only after the outbreak of the war did Germany set up relevant research groups.But from the point of view of Germany at that time, it was impossible to build an atomic bomb, because even if it was technically possible, there was still a problem of insufficient resources, especially the need for more heavy water. After returning to Germany, Heisenberg drafted a more detailed statement.Generally speaking, the German team has long realized that uranium 235 can be used as a reactor or a bomb, but it is extremely difficult to separate the rare isotope uranium 235 from natural uranium. (*Here is a supplement to the common sense of the atomic bomb: when a neutron bombards the easily split uranium 235 nucleus, it will be split in half, and more neutrons will be released to further bombard other nuclei. This will cause a series of chains The reaction, releasing a large amount of energy every time it splits, is what is commonly called a "chain reaction". But only uranium 235 is unstable and easily fissile, and its isotope uranium 238 is not, so the concentration of uranium 235 must be increased Only then can a sustainable reaction be triggered, otherwise all neutrons will be absorbed by uranium 238. But uranium 238 accounts for more than 99% of natural uranium, so it is extremely difficult to separate that little uranium 235 from the technology at that time of.) Heisenberg said that separating enough uranium-235 required a lot of resources and manpower and material resources, and this work was difficult to complete during the war.German scientists also became aware of another possible method, which is that although uranium-238 itself cannot be split, it absorbs neutrons and decays into another element, plutonium.And this element, like uranium 235, can form a chain reaction.But in any case, the premise is that there must be an atomic reactor, and the reactor that makes atoms needs a neutron moderator.A good moderator was heavy water, but for Germany the only source of heavy water was a factory in Norway which had been repeatedly damaged by Allied contingents and was rendered unusable. All in all, Heisenberg's subtext was that German scientists had the same theoretical and technical advantages as Allied scientists.But because Germany lacked corresponding resources, the Germans gave up this plan.He claimed that until 1942, the progress of the two sides was "basically the same", but due to the influence of external factors, Germany believed that it had no conditions (not no theoretical ability) to build an atomic bomb during the war, so it turned to the research of reactor energy . Heisenberg claimed that German scientists were aware from the beginning of the moral problems posed by the atomic bomb, and that such a destructive weapon made them aware of their responsibilities to humanity.But obligations to the state (not the Nazis) forced them to work.However, they were contradictory, passive and sabotaged, and intentionally or unintentionally exaggerated the difficulty of manufacturing, so in 1942 they convinced the top management that the atomic bomb had no practical significance.Coupled with the fact that the deterioration of the external environment made actual manufacturing impossible, German scientists were relieved, because they did not have to make this moral dilemma in person like Antigone in the tragedy. In this way, the scientific superiority of the Germans was maintained while at the same time a moral status was defended.The best of both worlds. This statement angered Goldschmidt, who was a key leader of the Manhattan Project during the war and was originally a good friend of Heisenberg.He thought it was nonsense to say that the Germans knew as well as the Allies the technical principles and key parameters of the atomic bomb. In 1942, Heisenberg reported that it was difficult to manufacture an atomic bomb in a short period of time. It was because the Germans miscalculated the parameters. They really believed that it was impossible to manufacture it.Goldschmidt has a special position and holds a lot of information in his hands, including Germany's own secret report. He soon wrote a book called ALSOS, which mainly introduced the process of the Manhattan Project, but also reported the situation in Germany.How could Heisenberg agree with them? The two debated publicly in Nature magazine and newspapers, fought off and on for many years, and finally made peace in private. Both sides have supporters. Kaempffert, a correspondent of the New York Times, defended Heisenberg and said something that caused an uproar: "Liars don't get the Nobel Prize!" The implication is that Goldschmidt lied.This feeling is definitely not good for the latter. We all know that Goldschmidt is one of the discoverers of electron spin. Many people complained that he did not win the Nobel Prize for such a great discovery. Schuman, the publisher of ALSOS, really wrote to Einstein, asking, "Do Nobel Prize winners really not lie?" Some lucky people may lie under pressure on certain occasions." Einstein probably thought of Lenard and Stark, two bona fide Nobel laureates, attacking him and the theory of relativity for fanatical Nazi beliefs, still before his eyes. three Flowers are blooming and falling, yellow leaves are falling, and it is autumn season again. The sixth Solvay Conference was held in Brussels.Bohr was apprehensive when he came to the venue. Seeing Einstein's half-smile, he wondered what new tricks he had practiced in the past three years, and what level he had reached.However, Bohr was not too worried. The rise of quantum theory was a certainty, and now the whole system had already established itself and grown luxuriantly.No matter how powerful Einstein is, it is difficult for one person to shake its foundation.Bohr's disciples back then, Heisenberg, Pauli, etc., are now independent great masters. The Copenhagen School is famous throughout the physics world, and Bohr is confident that he will not suffer a big loss. Einstein was thinking of another thing: Quantum theory was in its infancy, and it was too strong to defeat it.But is the law of causality and classical theory just finished?Impossible, quantum theory must be wrong!Well, after much deliberation, in order to break quantum theory, the only way to get rid of it is to defeat its foundation.Einstein knew from his experience fighting Bohr that he couldn’t argue about the details. Quantum theory is like the hydra in mythology. There will be another one.It is necessary to aim at the most critical head, which is the essence of it - the principle of uncertainty! Einstein stood up and spoke: Imagine a box with a small hole on it and a shutter that can be controlled to open and close. There are several photons in the box.Well, assuming the shutter can be controlled well enough that it opens so briefly at a time that only one photon is allowed to fly from the box to the outside at a time.Because the time is extremely short, Δt is small enough.So now there is one less photon in the box, and it is a little lighter, which can be measured with an ideal scale.If it is lighter by △m, then it means that the weight of the flying photon is m. According to the mass-energy equation E=mc^2 of the theory of relativity, the reduced energy △E can be accurately calculated. Then, △E and △t are very certain, and Heisenberg's formula △E×△t > h/2π is not valid.So the whole quantum theory is wrong! This can be said to be the blow of Einstein's life-long efforts, which also includes his famous stunt theory of relativity.This move is like a white rainbow penetrating the sun, hitting the vital point, calm and sophisticated, clean and beautiful.Bohr was unprepared for this. He was so taken aback that he couldn't think of any way to fight back.According to eyewitnesses, he became ashen-faced, transfixed (not figuratively!), and speechless.All night he was unhappy, scratching his stomach, brooding. Rosenfeld later described it: "(Bohr) tried to convince everyone that what Einstein said couldn't be true, or that would be the end of physics. But he couldn't think of any counterargument. I'll never forget the two The scene when the two opponents left the venue: Einstein, tall and solemn, walked out quietly with a mocking smile. Bohr trotted all the way behind. He was so excited that he argued that if love Einstein's device actually works, and physics is doomed." This move is really so pure and perfect, impeccable?Bohr tried his best to turn the tide at this critical moment, showing his true qualities as a hero.他经过一夜苦思，终于想出了破解此招的方法，一个更加妙到巅毫的巧招。 罗森菲尔德接着说： “第二天早上，玻尔的胜利便到来了。物理学也得救了。” 玻尔指出：好，一个光子跑了，箱子轻了△m。我们怎么测量这个△m呢？用一个弹簧称，设置一个零点，然后看箱子位移了多少。假设位移为△q吧，这样箱子就在引力场中移动了△q的距离，但根据广义相对论的红移效应，这样的话时间的快慢也要随之改变相应的△T。可以根据公式计算出：△T>h/△mc^2。再代以质能公式△E=△mc^2，则得到最终的结果，这结果是如此眼熟：△T△E > h，正是海森堡测不准关系！ 我们可以不理会数学推导，关键是爱因斯坦忽略了广义相对论的红移效应！引力场可以使原子频率变低，也就是红移，等效于时间变慢。当我们测量一个很准确的△m时，我们在很大程度上改变了箱子里的时钟，造成了一个很大的不确定的△T。也就是说，在爱因斯坦的装置里，假如我们准确地测量△m，或者△E时，我们就根本没法控制光子逃出的时间T！ 广义相对论本是爱因斯坦的独门绝技，玻尔这一招“以彼之道，还施彼身”不但封挡住了爱因斯坦那雷霆万钧的一击，更把这诸般招数都回加到了他自己身上。虽说是殚精竭虑最后想出此法，但招数精奇，才气横溢，教人击节叹服，大开眼界。觉得见证两大纵世奇才出全力相拚，实在不虚此行。 现在轮到爱因斯坦自己说不出话来了。难道量子论当真天命所归，严格的因果性当真已经迟迟老去，不再属于这个叛逆的新时代？玻尔是最坚决的革命派，他的思想闳廓深远，穷幽极渺，却又如大江奔流，浩浩荡荡，翻腾不息。物理学的未来只有靠量子，这个古怪却又强大的精灵去开拓。新世界不再有因果性，不再有实在性，可能让人觉得不太安全，但它却是那样胸怀博大，气派磅礴，到处都有珍贵的宝藏和激动人心的秘密等待着人们去发掘。狄拉克后来有一次说，自海森堡取得突破以来，理论物理进入了前所未有的黄金年代，任何一个二流的学生都可能在其中作出一流的发现。是的，人们应当毫不畏惧地走进这样一个生机勃勃的，充满了艰险、挑战和无上光荣的新时代中来，把过时的因果性做成一个纪念物，装饰在泛黄的老照片上去回味旧日的似水年华。 革命！go ahead!玻尔在大会上又开始显得精神抖擞，豪气万丈。爱因斯坦的这个光箱实验非但没能击倒量子论，反而成了它最好的证明，给它的光辉又添上了浓重的一笔。现在没什么好怀疑的了，因果性是不存在的，哥本哈根解释如野火一般在人们的思想中蔓延开来。玻尔是这场革命的旗手，他慷慨陈词，就像当年在议会前的罗伯斯庇尔。要是可能的话，他大概真想来上这么一句： 因果性必须死，因为物理学需要生！ 停止争论吧，上帝真的掷骰子！随机性是世界的基石，当电子出现在这里时，它是一个随机的过程，并不需要有谁给它加上难以忍受的条条框框。全世界的粒子和波现在都得到了解放，从牛顿和麦克斯韦写好的剧本中挣扎出来，大口地呼吸自由空气。它们和观测者玩捉迷藏，在他们背后融化成概率波弥散开去，神秘地互相渗透和干涉。当观测者回过头去寻找它们，它们又快乐地现出原型，呈现出一个面貌等候在那里。这种游戏不致于过火，因为还有波动方程和不确定原理在起着规则的作用。而统计规律则把微观上的无法无天抹平成为宏观上的井井有条。 爱因斯坦失望地看着这个场面，发展到如此地步实在让他始料不及。没有因果性，一片混乱……恐怕约翰?米尔顿描绘的那个“群魔殿”（Pandemonium）就是这个样子吧？爱因斯坦对玻尔已经两战两败，他现在知道量子论的根基比想象的要牢固得多。看起来，量子论不太可能是错误的，或者自相矛盾的。 但爱因斯坦也决不会相信它代表了真相。好吧，量子论内部是没有矛盾的，但它并不是一幅“完整”的图像。我们看到的量子论，可能只是管中窥豹，虽然看到了真实的一部分，但仍然有更多的“真实”未能发现。一定有一些其他的因素，它们虽然不为我们所见，但无疑对电子的行为有着影响，从而严格地决定了它们的行为。好比我们在赌场扔骰子赌钱，虽然我们睁大眼睛看明白四周一切，确定没人作弊，但的确可能还有一个暗中的武林高手，凭借一些独门手法比如说吹气来影响骰子的结果。虽然我们水平不行，发现不了这个武林高手的存在，觉得骰子是完全随机的，但事实上不是！它是完全人为的，如果把这个隐藏的高手也考虑进去，它是有严格因果关系的！尽管单单从我们看到的来讲，也没有什么互相矛盾，但一幅“完整”的图像应该包含那个隐藏着的人，这个人是一个“隐变量”！ 不管怎么说，因果关系不能抛弃！爱因斯坦的信念到此时几乎变成一种信仰了，他已决定终生为经典理论而战，这不知算是科学的悲剧还是收获。一方面，那个大无畏的领路人，那个激情无限的开拓者永远地从历史上消失了。亚伯拉罕?帕斯（Abraham Pais）在《爱因斯坦曾住在这里》一书中说，就算1925年后，爱因斯坦改行钓鱼以度过余生，这对科学来说也没什么损失。但另一方面，爱因斯坦对量子论的批评和诘问也确实使它时时三省吾身，冷静地审视和思考自己存在的意义，并不断地在斗争中完善自己。大概可算一种反面的激励吧？ 反正他不久又要提出一个新的实验，作为对量子论的进一步考验。可怜的玻尔得第三次接招了。 *********** 饭后闲话：海森堡和德国原子弹计划（三） 玩味一下海森堡的声明是很有意思的：讨厌纳粹和希特勒，但忠实地执行对祖国的义务，作为国家机器的一部分来履行爱国的职责。这听起来的确像一幅典型的德国式场景。服从，这是德国文化的一部分，在英语世界的人们看来，对付一个邪恶的政权，符合道德的方式是不与之合作甚至摧毁它，但对海森堡等人来说，符合道德的方式是服从它——正如他以后所说的那样，虽然纳粹占领全欧洲不是什么好事，但对一个德国人来说，也许要好过被别人占领，一战后那种惨痛的景象已经不堪回首。 原子弹，对于海森堡来说，是“本质上”邪恶的，不管它是为希特勒服务，还是为别的什么人服务。战后在西方科学家中有一种对海森堡的普遍憎恶情绪。当海森堡后来访问洛斯阿拉莫斯时，那里的科学家拒绝同其握手，因为他是“为希特勒制造原子弹的人”。这在海森堡看来是天大的委屈，他不敢相信，那些“实际制造了原子弹的人”竟然拒绝与他握手！也许在他心中，盟军的科学家比自己更加应该在道德上加以谴责。但显然在后者看来，只有为希特勒制造原子弹才是邪恶，如果以消灭希特勒和法西斯为目的而研究这种武器，那是非常正义和道德的。 这种道德观的差异普遍存在于双方阵营之中。魏扎克曾经激动地说：“历史将见证，是美国人和英国人造出了一颗炸弹，而同时德国人——在希特勒政权下的德国人——只发展了铀引擎动力的和平研究。”这在一个美国人看来，恐怕要喷饭。 何况在许多人看来，这种声明纯粹是马后炮。要是德国人真的造得出来原子弹，恐怕伦敦已经从地球上消失了，也不会罗里罗嗦地讲这一大通风凉话。不错，海森堡肯定在1940年就意识到铀炸弹是可能的，但这不表明他确切地知道到底怎么去制造啊！海森堡在1942年意识到以德国的环境来说分离铀235十分困难，但这不表明他确切地知道到底要分离“多少”铀235啊！事实上，许多证据表明，海森堡非常错误地估计了工程量，为了维持链式反应，必须至少要有一个最小量的铀235才行，这个质量叫做“临界质量”（critical mass），海森堡——不管他是真的算错还是假装不知——在1942年认为至少需要几吨的铀235才能造出原子弹！事实上，只要几十千克就可以了。