Chapter 9 Chapter Eight Controversy

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, Como, which entered the First Division last season (2002︱2003), but is now relegated.It was once reported that it was interested in the Chinese player Wu Chengying, which is 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, and his statue has stood here 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 a hundred 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 had other responsibilities and could not attend.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 Physics Department of the 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.

But in 1927 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 several hours.

However, no matter what, Bohr finally completed the eight-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 at all familiar with the ideas and work of Bohr and others, and this principle of complementarity is puzzling to them.Many people think that this is just a play on words, just another way of saying what everyone knows.As Rosenfeld later commented in the interview program: This principle of complementarity is just an explanation of what everyone knows clearly. The Cuomo meeting did not have clear arguments, and the definition of the concept was not made until later.Eugene.Eugene Wigner concluded: (Bohr's lecture, by all accounts) 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, the cause and the result, 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 would never be forced to abandon strict causality and would defend it vigorously.I find it totally intolerable to think that the electron, exposed to radiation, chooses not only the moment of its transition, but also the direction of its transition, by its own free will.

The old quantum theory had already made Einstein unable to agree, so the crazier new quantum theory made him even more 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, and 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, juniors like Feynman are simply inconspicuous, and Los Alamos is also known as a concentration camp for Nobel Prize winners.But Germany is not bad at all.Yes, Hitler’s Jewish policy drove away almost half of the country’s elite. In the first year the Nazis came to power, about 2,600 scholars left Germany, and a quarter of physicists resigned from German universities. Go, forty percent of university professors had lost their jobs by the eve of the war.Yes, the entire Axis lost as many as twenty-seven Nobel Prize winners, including even the most outstanding figures such as Einstein, Schrödinger, Fermi, Born, Pauli, Debye, and this number does not count Indirect losses such as Bohr and the like.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.At that time, it was 1939, and only Germany in the world 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 Frieze.Fritz Strassmann (Fritz Strassmann) discovered the previous year, both of them were still in Germany, and Hahn would later win the Nobel Prize in Chemistry for his discovery.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 alpha scattering Experiment), Karl von Weizsacker, Erich Bagge, Kurt Diebner, Walther Gerlach, Karl Wirtz, and of course, Heisenberg, One of the greatest physicists of the twentieth century.All of these scientists participated in Hitler's atomic bomb program and became members of the Uranium Club, of which Heisenberg was in charge. However, Germany failed to build the atomic bomb, it didn't even have access to it.Since 1942, Germany seems to have abandoned the entire atomic bomb program, and instead studied the construction of a nuclear reactor that can provide energy.The main reason is that in June 1942, Heisenberg reported to Armaments Minister Albert Speer that the uranium program was unable to produce any practical results in a short period of time due to technical reasons, causing An atomic bomb is 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, any plan that could not be effective in a short period of time, to be precise, six weeks. was temporarily set aside.Hitler and Speer reached an agreement: there is no need to spend too much effort on the atomic bomb, but since it is still ahead in this area, it might 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 impact with or without it. After nearly two years of laissez-faire at the top, the plan finally came to Himmler's attention 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 then, all of Germany's industries 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 about 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 riddle in the history of science. two The Solvay Conference was founded by and named after a Belgian industrialist, Ernest Solvay.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 regularly 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 meeting lasted six 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 gave an experimental report on X-rays, and then Compton 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 image of waves, and proposed a theory of pivot wave. He believed that particles are a singular point of the wave equation and must be controlled by waves. and boot.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 bunker in Copenhagen and opened fire on it. They said at the end of the report: We maintain that quantum mechanics is a complete theory, and its basic physical and mathematical assumptions cannot be further modified.They also focused their fire on Schrödinger's electron cloud, which suggested that the electrons did indeed spread out like waves in space.Heisenberg commented: I don't see anything from Schrödinger's calculations to prove that the facts are what he hoped they would be.Schrödinger admitted that his calculations were indeed unsatisfactory, but he still insisted that talking about the orbit of electrons is nonsense (should be the superposition of Bourbon's eigenstates), and Born replied: No, it is not nonsense at all.In the midst of the smoke, the organizer of the meeting, the veteran Lorenz, also expressed some conservative views, 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 electron, 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, and 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 on the sensing screen respond simultaneously to the electron's observations, this seems to imply an action at a distance, thus violating the theory of 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 "Discussions with Einstein on Epistemological Issues in Atomic Physics" that Bohr himself was invited to write to celebrate Einstein's 70th birthday in 1949, Heisenberg, Deb Memories and letters of Roy and Ehrenfest, etc.At that time, there was a fierce battle, and among the problems discussed were 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 rapidly closing/opening a slit 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 soon turned into a duel between Einstein and Bohr: To what extent could the then atomic theory be seen as the final answer to the difficulties that had been discussed for decades?We usually met over breakfast in a hotel, so Einstein described a thought experiment from 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 listen to the discussion of these two people with very different philosophical attitudes, and I often inserted a few words in terms of the structure of mathematical expressions.In the middle of the meeting, especially during the breaks, we young people, mostly me and Pauli, tried to analyze Einstein's experiments, and at lunch the discussion was between Bohr and others from Copenhagen. in between.Generally speaking, Bohr had a complete idea of ​​these ideal experiments in the evening, and he would analyze them to Einstein at dinner.Einstein could not refute these analyses, 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 w'rfelt)? God doesn't play dice!This is not the first time Einstein has said this.In a letter to Born as early as 1926, he said: Quantum mechanics is impressive, but an inner voice tells me it is not real.This theory yields many good results, but it does not bring us any closer to the old man's mystery.I believe without reservation that the old man does not play dice. Don is 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! Bonn lamented: We have lost our leader. 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 have been widely accepted. refutation, even Einstein and Schrödinger can't do it.Years later he concluded: At first 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, have the tragic spirit of long-term coldness, easy water, and vowing to live and die with the classical theory in the dawn of the quantum age. 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, but in order to get Heisenberg, the first target, the Allied forces sent a small detachment to the Urfeld in May. On the third day, that is, the fourth day after Hitler and his wife 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, the news of the atomic bombing of Hiroshima came, which left 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 releases a large amount of energy every time it splits, which is what is commonly referred to as 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 to trigger Sustainable reaction, otherwise all neutrons would be absorbed by uranium 238. However, uranium 238 accounts for more than 99% of natural uranium, so it was 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.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.However, the Germans abandoned this plan because of the lack of corresponding resources in Germany.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 (rather than no theoretical ability) to build an atomic bomb during the war, so it switched to reactor energy. Research. 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 ambivalent, 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 for the New York Times, defended Heisenberg with a statement that caused an uproar: Liars don't get Nobel Prizes!The implication is naturally that Gudschmidt is lying.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 if Nobel laureates really don't lie?Einstein had no choice but to write back and said: Lying cannot win the Nobel, but it cannot be ruled out that some lucky people may lie under pressure on specific 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.You must aim at the most critical head, which is the essence of the uncertainty principle! 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, and 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) lobbied everyone hard, trying to convince them that what Einstein said couldn't be true, or that would be the end of physics.But he could think of no rebuttal.I will never forget the scene when the two opponents left the venue: Einstein walked out quietly with a tall and solemn figure, with a mocking smile.Bohr trotted after him, excited and incoherently arguing that if Einstein's device really worked, physics would be 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.他經過一夜苦思，終於想出了破解此招的方法，一個更加妙到巔毫的巧招。 羅森菲爾德接著說： 第二天早上，玻爾的勝利便到來了。物理學也得救了。 玻爾指出：好，一個光子跑了，箱子輕了△m。我們怎麼測量這個△m呢？用一個彈簧秤，設置一個零點，然後看箱子位移了多少。假設位移為△q吧，這樣箱子就在引力場中移動了△q的距離，但根據廣義相對論的紅移效應，這樣的話時間的快慢也要隨之改變相應的△T。可以根據公式計算出：△T>h／△mc^2。再代以質能公式△E＝△mc^2，則得到最終的結果，這結果是如此眼熟：△T△E >h，正是海森堡測不準關係！ 我們可以不理會數學推導，關鍵是愛因斯坦忽略了廣義相對論的紅移效應！引力場可以使原子頻率變低，也就是紅移，等效於時間變慢。當我們測量一個很準確的△m時，我們在很大程度上改變了箱子裡的時鐘，造成了一個很大的不確定的△T。也就是說，在愛因斯坦的裝置裡，假如我們準確地測量△m，或者△E時，我們就根本沒法控制光子逃出的時間T！ 廣義相對論本是愛因斯坦的獨門絕技，玻爾這一招以彼之道，還施彼身不但封擋住了愛因斯坦那雷霆萬鈞的一擊，更把這諸般招數都回加到了他自己身上。雖說是殫精竭慮最後想出此法，但招數精奇，才氣橫溢，教人擊節嘆服，大開眼界。覺得見證兩大縱世奇才出全力相拚，實在不虛此行。 現在輪到愛因斯坦自己說不出話來了。難道量子論當真天命所歸，嚴格的因果性當真已經遲遲老去，不再屬於這個叛逆的新時代？玻爾是最堅決的革命派，他的思想閎廓深遠，窮幽極渺，卻又如大江奔流，浩浩蕩蕩，翻騰不息。物理學的未來只有靠量子，這個古怪卻又強大的精靈去開拓。新世界不再有因果性，不再有實在性，可能讓人覺得不太安全，但它卻是那樣胸懷博大，氣派磅礴，到處都有珍貴的寶藏和激動人心的秘密等待著人們去發掘。狄拉克後來有一次說，自海森堡取得突破以來，理論物理進入了前所未有的黃金年代，任何一個二流的學生都可能在其中作出一流的發現。是的，人們應當毫不畏懼地走進這樣一個生機勃勃的，充滿了艱險、挑戰和無上光榮的新時代中來，把過時的因果性做成一個紀念物，裝飾在泛黃的老照片上去回味舊日的似水年華。 革命！go ahead!玻爾在大會上又開始顯得精神抖擻，豪氣萬丈。愛因斯坦的這個光箱實驗非但沒能擊倒量子論，反而成了它最好的證明，給它的光輝又添上了濃重的一筆。現在沒什麼好懷疑的了，因果性是不存在的，哥本哈根解釋如野火一般在人們的思想中蔓延開來。玻爾是這場革命的旗手，他慷慨陳詞，就像當年在議會前的羅伯斯庇爾。要是可能的話，他大概真想來上這麼一句： 因果性必須死，因為物理學需要生！ 停止爭論吧，上帝真的擲骰子！隨機性是世界的基石，當電子出現在這裡時，它是一個隨機的過程，並不需要有誰給它加上難以忍受的條條框框。全世界的粒子和波現在都得到了解放，從牛頓和麥克斯韋寫好的劇本中掙扎出來，大口地呼吸自由空氣。它們和觀測者玩捉迷藏，在他們背後融化成概率波彌散開去，神秘地互相滲透和干涉。當觀測者回過頭去尋找它們，它們又快樂地現出原型，呈現出一個面貌等候在那裡。這種遊戲不致於過火，因為還有波動方程和不確定原理在起著規則的作用。而統計規律則把微觀上的無法無天抹平成為宏觀上的井井有條。 愛因斯坦失望地看著這個場面，發展到如此地步實在讓他始料不及。沒有因果性，一片混亂恐怕約翰．密爾頓描繪的那個群魔殿（Pandemonium）就是這個樣子吧？愛因斯坦對玻爾已經兩戰兩敗，他現在知道量子論的根基比想像的要牢固得多。看起來，量子論不太可能是錯誤的，或者自相矛盾的。 但愛因斯坦也決不會相信它代表了真相。好吧，量子論內部是沒有矛盾的，但它並不是一幅完整的圖像。我們看到的量子論，可能只是管中窺豹，雖然看到了真實的一部分，但仍然有更多的真實未能發現。一定有一些其他的因素，它們雖然不為我們所見，但無疑對電子的行為有著影響，從而嚴格地決定了它們的行為。好比我們在賭場扔骰子賭錢，雖然我們睜大眼睛看明白四周一切，確定沒人作弊，但的確可能還有一個暗中的武林高手，憑藉一些獨門手法比如說吹氣來影響骰子的結果。雖然我們水準不行，發現不了這個武林高手的存在，覺得骰子是完全隨機的，但事實上不是！它是完全人為的，如果把這個隱藏的高手也考慮進去，它是有嚴格因果關係的！儘管單單從我們看到的來講，也沒有什麼互相矛盾，但一幅完整的圖像應該包含那個隱藏著的人，這個人是一個隱變數！ 不管怎麼說，因果關係不能拋棄！愛因斯坦的信念到此時幾乎變成一種信仰了，他已決定終生為經典理論而戰，這不知算是科學的悲劇還是收穫。一方面，那個大無畏的領路人，那個激情無限的開拓者永遠地從歷史上消失了。Abraham.帕斯（Abraham Pais）在《愛因斯坦曾住在這裡》一書中說，就算一九二五年後，愛因斯坦改行釣魚以度過餘生，這對科學來說也沒什麼損失。但另一方面，愛因斯坦對量子論的批評和詰問也確實使它時時三省吾身，冷靜地審視和思考自己存在的意義，並不斷地在鬥爭中完善自己。大概可算一種反面的激勵吧？ 反正他不久又要提出一個新的實驗，作為對量子論的進一步考驗。可憐的玻爾得第三次接招了。 飯後閒話：海森堡和德國原子彈計畫（三） 玩味一下海森堡的聲明是很有意思的：討厭納粹和希特勒，但忠實地執行對祖國的義務，作為國家機器的一部分來履行愛國的職責。這聽起來的確像一幅典型的德國式場景。服從，這是德國文化的一部分，在英語世界的人們看來，對付一個邪惡的政權，符合道德的方式是不與之合作甚至摧毀它，但對海森堡等人來說，符合道德的方式是服從它正如他以後所說的那樣，雖然納粹佔領全歐洲不是什麼好事，但對一個德國人來說，也許要好過被別人佔領，一戰後那種慘痛的景象已經不堪回首。 原子彈，對於海森堡來說，是本質上邪惡的，不管它是為希特勒服務，還是為別的什麼人服務。戰後在西方科學家中有一種對海森堡的普遍憎惡情緒。當海森堡後來訪問洛斯阿拉莫斯時，那裡的科學家拒絕同其握手，因為他是為希特勒製造原子彈的人。這在海森堡看來是天大的委屈，他不敢相信，那些實際製造了原子彈的人竟然拒絕與他握手！也許在他心中，盟軍的科學家比自己更加應該在道德上加以譴責。但顯然在後者看來，只有為希特勒製造原子彈才是邪惡，如果以消滅希特勒和法西斯為目的而研究這種武器，那是非常正義和道德的。 這種道德觀的差異普遍存在於雙方陣營之中。魏紮克曾經激動地說：歷史將見證，是美國人和英國人造出了一顆炸彈，而同時德國人在希特勒政權下的德國人只發展了鈾引擎動力的和平研究。這在一個美國人看來，恐怕要噴飯。 何況在許多人看來，這種聲明純粹是馬後炮。要是德國人真的造得出來原子彈，恐怕倫敦已經從地球上消失了，也不會囉哩囉嗦地講這一大通風涼話。不錯，海森堡肯定在一九四○年就意識到鈾炸彈是可能的，但這不表明他確切地知道到底怎麼去製造啊！海森堡在一九四二年意識到以德國的環境來說分離鈾235十分困難，但這不表明他確切地知道到底要分離多少鈾235啊！事實上，許多證據表明，海森堡非常錯誤地估計了工程量，為了維持鏈式反應，必須至少要有一個最小量的鈾235才行，這個品質叫做臨界品質（critical mass），海森堡不管他是真的算錯還是假裝不知在一九四二年認為至少需要幾噸的鈾235才能造出原子彈！事實上，只要幾十千克就可以了。 誠然，即使只分離這麼一點點鈾235也是非常困難的。美國動用了一萬五千人，投資超過二十億美元才完成整個曼哈頓計畫。而德國整個只有一百多人在搞這事，總資金不過百萬馬克左右，這簡直是笑話。但這都不是關鍵，關鍵是，海森堡到底知不知道準確的數字？如果他的確有一個準確數字的概念，那麼雖然這德國來說仍然是困難的，但至少不是那樣的遙不可及，難以克服。英國也同樣困難，但他們知道準確的臨界質量數字，於是仍然上馬了原子彈計畫。 海森堡爭辯說，他對此非常清楚，他引用了許多證據說明在與斯佩爾會面前他的確知道準確的數字。可惜他的證據全都模糊不清，無法確定。德國的報告上的確說一個炸彈可能需要十-一百千克，海森堡也描繪過一個鳳梨大小的炸彈，這被許多人看作證明。然而這些全都是指鈾炸彈，而不是鈾235炸彈。這些數字不是證明出來的，而是猜測的，德國根本沒有反應堆來大量生產。德國科學家們在許多時候都流露出這樣的印象，鈾炸彈至少需要幾噸的鈾235。 不過當然你也可以從反方面去理解，海森堡故意隱瞞了數位，只有天知地知他一個人知。他一手造成誇大了的假相。 至於反應堆，其實石墨也可以做很好的減速劑，美國人就是用的石墨。可是當時海森堡委派波特去做實驗，他的結果錯了好幾倍，顯示石墨不適合用在反應堆中，於是德國人只好在重水這一棵樹上吊死。這又是一個懸案，海森堡把責任推到波特身上，說他用的石墨不純，因此導致了整個計畫失敗。波特是非常有名的實驗物理學家，後來也得了諾貝爾獎，這個黑鍋如何肯背。他給海森堡寫信，暗示說石墨是純的，而且和理論相符合！如果說實驗錯了，那還不如說理論錯了，理論可是海森堡負責的。在最初的聲明中海森堡被迫撤回了對波特的指責，但在以後的歲月中，他，魏紮克，沃茲等人仍然不斷地把波特拉進來頂罪。目前看來，德國人當年無論是理論還是實驗上都錯了。 對這一公案的爭論逐漸激烈起來，最有影響的幾本著作有：Robert Jungk的《比一千個太陽更明亮》（Brighter Than a Thousand Suns，一九五六），此書讚揚了德國科學家那高尚的道義，在戰時不忘人類公德，雖然洞察原子彈的奧秘，卻不打開這潘朵拉盒子。一九六七年David Irving出版了《德國原子彈計畫》（The German Atomic Bomb），此時德國當年的秘密武器報告已經得見天日，給作品帶來了豐富的資料。Irving雖然不認為德國科學家有吹噓的那樣高尚的品德，但他仍然相信當年德國人是清楚原子彈技術的。然後是Margaret Gowing那本關於英國核計畫的歷史，裡面考證說德國人當年在一些基本問題上錯得離譜，這讓海森堡本人非常惱火。他說：（這本書）大錯特錯，每一句都是錯的，完全是胡說八道。他隨後出版了著名的自傳《物理和物理之外》（Physics and Beyond），自然再次地強調了德國人的道德和科學水準。凡是當年和此事有點關係的人都紛紛發表評論意見，眾說紛紜，有如聚訟，誰也沒法說服對方。 一九八九年，楊振寧在上海交大演講的時候還說：很好的海森堡傳記至今還沒寫出，而已有的傳記對這件事是語焉不詳的這是一段非常複雜的歷史，我相信將來有人會寫出重要的有關海森堡的傳記。 幸運的是，從那時起到今天，事情總算是如其所願，有了根本性的變化。 Four 愛因斯坦沒有出席一九三三年第七屆索爾維會議，他被納粹德國逼得離開家鄉，流落異國，憂鬱地思索著歐洲那悲慘的未來。另一方面，這屆索爾維會議的議題也早就不是量子論本身，而換成了另一個激動人心的話題：爆炸般發展的原子物理。不過這個領域裡的成就當然也是在量子論的基礎上取得的，而量子力學的基本形式已經確定下來，成為物理學的基礎。似乎是塵埃落定，沒什麼人再懷疑它的力量和正確性了。 在人們的一片樂觀情緒中，愛因斯坦和薛定諤等寥寥幾人愈加顯得孤獨起來。薛定諤和德布羅意參加了一九三三年索爾維會議，卻都沒有發言，也許是他們對這一領域不太熟悉的緣故吧。新新人類們在激動地探討物質的產生和湮滅、正電子、重水、中子那樣多的新發現讓人眼花繚亂，根本忙不過來。而愛因斯坦他們現在還能做什麼呢？難道他們的思想真的已經如此過時，以致跟不上新時代那飛一般的步伐了嗎？ 一九三三年九月二十五日，埃侖費斯特在荷蘭萊登槍殺了他那患有智力障礙的兒子，然後自殺了。他在留給愛因斯坦，玻爾等好友的信中說：這幾年我越來越難以理解物理學的飛速發展，我努力嘗試，卻更為絕望和撕心裂肺，我終於決定放棄一切。我的生活令人極度厭倦我僅僅是為了孩子們的經濟來源而活著，這使我感到罪惡。我試過別的方法但是收效甚微，因此我越來越多地去考慮自殺的種種細節，除此之外我沒有第二條路走了原諒我吧。 在愛因斯坦看來，埃侖費斯特的悲劇無疑是一個時代的悲劇。兩代物理學家的思想猛烈衝突和撞擊，在一個天翻地覆的飄搖亂世，帶給整個物理學以強烈的陣痛。埃侖費斯特雖然從理智上支持玻爾，但當一個文化衰落之時，曾經為此文化所感之人必感到強烈的痛苦。昔日黃金時代的黯淡老去，代以雨後春筍般興起的新思潮，從量子到量子場論，原子中各種新粒子層出不窮，稀奇古怪的概念統治整個世界。愛因斯坦的心中何曾沒有埃侖費斯特那樣難以名狀的巨大憂傷？愛因斯坦遠遠地，孤獨地站在鴻溝的另一邊，看著年輕人們義無反顧地高唱著向遠方進軍，每一個人都對他說他站錯了地方。這種感覺是那樣奇怪，似乎世界都顯得朦朧而不真實。難怪曾經有人嘆息說，寧願早死幾年，也不願看到現代物理這樣一幅令人難以接受的畫面。不過，愛因斯坦卻仍然沒有倒下，雖然他身在異鄉，他的第二個妻子又重病纏身，不久將與他生離死別，可這一切都不能使愛因斯坦放棄內心那個堅強的信仰，那個對於堅固的因果關係，對於一個宇宙和諧秩序的癡癡信仰。愛因斯坦仍然選擇戰鬥，他的身影在斜陽下拉得那樣長，似乎是勇敢的老戰士為一個消逝的王國做最後的悲壯抗爭。 這一次他爭取到了兩個同盟軍，他們分別是他的兩個同事波多爾斯基（Boris Podolsky）和羅森（Nathan Rosen）。一九三五年三月，三人共同在《物理評論》（Physics Review）雜誌上發表了一篇論文，名字叫《量子力學對物理實在的描述可能是完備的嗎？》，再一次對量子論的基礎發起攻擊。當然他們改變策略，不再說量子論是自相矛盾，或者錯誤的，而改說它是不完備的。具體來說，三人爭辯量子論的那種對於觀察和波函數的解釋是不對的。 我們用一個稍稍簡化了的實驗來描述他們的主要論據。我們已經知道，量子論認為在我們沒有觀察之前，一個粒子的狀態是不確定的，它的波函數彌散開來，代表它的概率。但當我們探測以後，波函數坍縮，粒子隨機地取一個確定值出現在我們面前。 現在讓我們想像一個大粒子，它是不穩定的，很快就會衰變成兩個小粒子，向相反的兩個方向飛開去。我們假設這種粒子有兩種可能的自旋，分別叫左和右，那麼如果粒子A的自旋為左，粒子B的自旋便一定是右，以保持總體守恆，反之亦然。 好，現在大粒子分裂了，兩個小粒子相對飛了出去。但是要記住，在我們沒有觀察其中任何一個之前，它們的狀態都是不確定的，只有一個波函數可以描繪它們。只要我們不去探測，每個粒子的自旋便都處在一種左／右可能性疊加的混合狀態，為了方便我們假定兩種概率對半分，各五十％。 現在我們觀察粒子A，於是它的波函數一瞬間坍縮了，隨機地選擇了一種狀態，比如說是左旋。但是因為我們知道兩個粒子總體要守恆，那麼現在粒子B肯定就是右旋了。問題是，在這之前，粒子A和粒子B之間可能已經相隔非常遙遠的距離，比如說幾萬光年好了。它們怎麼能夠做到及時地互相通信，使得在粒子A坍縮成左的一剎那，粒子B毅然坍縮成右呢？ 量子論的概率解釋告訴我們，粒子A選擇左，那是一個完全隨機的決定，兩個粒子並沒有事先商量好，說粒子A一定會選擇左。事實上，這種選擇是它被觀測的那一剎那才做出的，並沒有先兆。關鍵在於，當A隨機地作出一個選擇時，遠在天邊的B便一定要根據它的決定而作出相應的坍縮，變成與A不同的狀態以保持總體守恆。那麼，B是如何得知這一遙遠的資訊的呢？難道有超過光速的信號來回於它們之間？ 假設有兩個觀察者在宇宙的兩端守株待兔，在某個時刻t，他們同時進行了觀測。一個觀測A，另一個同時觀測B，那麼，這兩個粒子會不會因為距離過於遙遠，一時無法對上口徑而在倉促間做出手忙腳亂的選擇，比如兩個同時變成了左，或者右？顯然是不太可能的，不然就違反了守恆定律，那麼是什麼讓它們之間保持著心有靈犀的默契，當你是左的時候，我一定是右？ 愛因斯坦等人認為，既然不可能有超過光速的信號傳播，那麼說粒子A和B在觀測前是不確定的幽靈顯然是難以自圓其說的。唯一的可能是兩個粒子從分離的一剎那開始，其狀態已經確定了，後來人們的觀測只不過是得到了這種狀態的資訊而已，就像經典世界中所描繪的那樣。粒子在觀測時才變成真實的說法顯然違背了相對論的原理，它其中涉及到瞬間傳播的信號。這個詰難以三位發起者的首字母命名，稱為EPR佯謬。 玻爾在得到這個消息後大吃一驚，他馬上放下手頭的其他工作，來全神貫注地對付愛因斯坦的這次挑戰。這套潛心演練的新陣法看起來氣勢洶洶，宏大堂皇，頗能奪人心魄，但玻爾也算是愛因斯坦的老對手了。他睡了一覺後，馬上發現了其中的破綻所在，原來這看上去讓人眼花繚亂的一次攻擊卻是個完完全全的虛招，並無實質力量。玻爾不禁得意地唱起一支小調，調侃了波多爾斯基一下。 原來愛因斯坦和玻爾根本沒有個共同的基礎。在愛因斯坦的潛意識裡，一直有個經典的實在影像。他不言而喻地假定，EPR實驗中的兩個粒子在觀察之前，分別都有個客觀的自旋狀態存在，就算是概率混合吧，但粒子客觀地存在於那裡。但玻爾的意思是，在觀測之前，沒有一個什麼粒子的自旋！那時候自旋的粒子是不存在的，不是客觀實在的一部分，這不能用經典語言來表達，只有波函數可以描述。因此在觀察之前，兩個粒子無論相隔多遠都好仍然是一個互相關聯的整體！它們仍然必須被看作母粒子分裂時的一個全部，直到觀察以前，這兩個獨立的粒子都是不存在的，更談不上客觀的自旋狀態！ 這是愛因斯坦和玻爾思想基礎的尖銳衝突，玻爾認為，當沒有觀測的時候，不存在一個客觀獨立的世界。所謂實在只有和觀測手段連起來講才有意義。在觀測之前，並沒有兩個粒子，而只有一個粒子，直到我們觀測了A或者B，兩個粒子才變成真實，變成客觀獨立的存在。但在那以前，它們仍然是互相聯繫的一個虛無整體。並不存在什麼超光速的信號，兩個遙遠的粒子只有到觀測的時候才同時出現在宇宙中，它們本是協調的一體，之間無需傳遞什麼信號。其實是這個系統沒有實在性，而不是沒有定域性。 EPR佯謬其實根本不是什麼佯謬，它最多表明了，在經典實在觀看來，量子論是不完備的，這簡直是廢話。但是在玻爾那種量子實在觀看來，它是非常完備和邏輯自洽的。 既生愛，何生玻。兩人的世紀爭論進入了尾聲。在哲學基礎上的不同使得兩人間的意見分歧直到最後也沒能調和。一直到死，玻爾也未能使愛因斯坦信服，認為量子論的解釋是完備的。而玻爾本人也一直在同愛因斯坦的思想作鬥爭，在他一九六二年去世後的第二天，人們在他的黑板上仍然發現畫有當年愛因斯坦光箱實驗的草圖。兩位科學巨人都為各自的信念而奮鬥了畢生，但別的科學家已經甚少關心這種爭執。在量子論的引導下，科學顯得如此朝氣蓬勃，它的各個分支以火箭般的速度發展，給人類社會帶來了偉大的技術革命。從半導體到核能，從鐳射到電子顯微鏡，從積體電路到分子生物學，量子論把它的光輝播撒到人類社會的每一個角落，成為有史以來在實用中最成功的物理理論。許多人覺得，爭論量子論到底對不對簡直太可笑了，只要轉過頭，看看身邊發生的一切，看看社會的日新月異，目光所及，無不是量子論的最好證明。 如果說EPR最大的價值所在，那就是它和別的奇想空談不同。只要稍微改裝一下，EPR是可以為實踐所檢驗的！我們的史話在以後會談到，人們是如何在實驗室裡用實踐裁決了愛因斯坦和玻爾的爭論，經典實在的概念無可奈何花落去，只留下一個蒼涼的背影和深沉的嘆息。 但量子論仍然困擾著我們。它的內在意義是如此撲朔迷離，使得對它的詮釋依舊眾說紛紜。量子論取得的成就是無可懷疑的，但人們一直無法確認它的真實面目所在，這爭論一直持續到今天。它將把一些讓物理學家們毛骨悚然的概念帶入物理中，令人一想來就不禁倒吸一口涼氣。而反對派那裡還有一個薛定諤，他要放出一隻可怕的怪獸，撕咬人們的理智和神經，這就是叫許多人聞之色變的薛定諤的貓。 飯後閒話：海森堡和德國原子彈計畫（四） 海森堡本人於一九七六年去世了。在他死後兩年，英國人Jones出版了《高度機密戰爭：英國科學情報部門》（Most Secret War: British Scientific Intelligentce）一書，詳細地分析了海森堡當年在計算時犯下的令人咋舌的錯誤。但他的分析卻沒有被Mark Walker所採信，在資料詳細的《德國國家社會主義及核力量的尋求》（German National Socialism and the Quest for Nubclear Power，一九八九年出版）中，Walker還是認為海森堡在一九四二年頭腦清楚，知道正確的事實。 到了一九九二年，Hofstra大學的大衛．凱西迪（David Cassidy）出版了著名的海森堡傳記《不確定性：海森堡傳》，這至今仍被認為是海森堡的標準傳記。他分析了整件事情，並最後站在了古德施密特等人的立場上，認為海森堡並沒有什麼主觀的願望去摧毀一個原子彈計畫，他當年確實算錯了。 但是很快到了一九九三年，戲劇性的情況又發生了。Thomas Powers寫出了巨著《海森堡的戰爭》（Heisenberg's War）。Powers本是記者出身，非常瞭解如何使得作品具有可讀性。因此雖然這本厚書足有六百零七頁，但文字奇巧，讀來引人入勝，很快成了暢銷作品。Powers言之鑿鑿地說，海森堡當年不僅僅是消極地對待原子彈計畫，他更是積極地破壞了這個計畫的成功實施。他繪聲繪色地向人們描繪了一幕幕陰謀、間諜、計畫，後來有人揶揄說，這本書的前半部分簡直就是一部間諜小說。不管怎麼樣說，這本書在公眾中的反響是很大的，海森堡作為一個高尚的，富有機智和正義感的科學家形象也深入人心，更直接影響了後來的戲劇《哥本哈根》。從以上的描述可以見到，對這件事的看法在短短幾年中產生了多少極端不同的看法，這在科學史上幾乎獨一無二。 一九九二年披露了一件非常重要的史料，那就是海森堡他們當初被囚在Farm Hall的竊聽錄音抄本。這個東東長期來是保密的，只能在幾個消息靈通者的著作中見到一星半點。一九九二年這份被稱為Farm Hall Transcript的檔解密，由加州大學伯克利出版，引起轟動。Powers就借助了這份新資料，寫出了他的著作。 《海森堡的戰爭》一書被英國記者兼劇作家Michael Frayn讀到，後者為其所深深吸引，不由產生了一個巧妙的戲劇構思。在海森堡之謎的核心，有一幕非常神秘，長期為人們爭議不休的場景，那就是一九四一年他對玻爾的訪問。當時丹麥已被德國佔領，納粹在全歐洲的攻勢勢如破竹。海森堡那時意識到了原子彈製造的可能性，他和魏紮克兩人急急地假借一個學術會議的名頭，跑到哥本哈根去會見當年的老師玻爾。這次會見的目的和談話內容一直不為人所知，玻爾本人對此隱諱莫深，絕口不談。唯一能夠確定的就是當時兩人鬧得很不愉快，玻爾和海森堡之間原本情若父子，但這次見面後多年的情義一朝了斷，只剩下表面上的客氣。What happened? 有人說，海森堡去警告玻爾讓他注意德國的計畫。有人說海森堡去試圖把玻爾也拉進他們的計畫中來。有人說海森堡想探聽盟軍在這方面的進展如何。有人說海森堡感到罪孽，要向玻爾這位教皇請求寬恕 Michael Frayn著迷於Powers的說法，海森堡去到哥本哈根向玻爾求證盟軍在這方面的進展，並試圖達成協議，雙方一起破壞這個可怕的計畫。也就是說，任何一方的科學家都不要積極投入到原子彈這個領域中去，這樣大家扯平，人類也可以得救。這幾乎是一幕可遇而不可求的戲劇場景，種種複雜的環境和內心衝突交織在一起，糾纏成千千情結，組成精采的高潮段落。一方面海森堡有強烈的愛國熱情和服從性，他無法拒絕為德國服務的命令。但海森堡又掙扎於人類的責任感，感受到科學家的道德情懷。而且他又是那樣生怕盟軍也造出原子彈，給祖國造成永遠的傷痕。海森堡面對玻爾，那個偉大的老師玻爾，那個他當作父親一樣看待的玻爾，曾經領導夢幻般哥本哈根派的玻爾，卻也是敵人玻爾，視德國為仇敵的玻爾，卻又教人如何開口，如何遣詞少年的回憶，物理上的思索，敬愛的師長，現實的政治，祖國的感情，人類的道德責任，戰爭年代這些融在一起會產生怎樣的語言和思緒？還有比這更傑出的戲劇題材嗎？ 《哥本哈根》的第一幕