The Rebirth of Physics in Italy
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Lindau Nobel Laureate Meetings128 / 340
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00:00
Particle physicsYearHot workingRRS DiscoveryFinger protocolForceGroup delay and phase delayKardierenAtomismParticle physicsColumbia, KentuckyHourRail transport operationsElectronic mediaStormProzessleittechnikAnomaly (physics)GentlemanArtillery batteryMeasurementElectricityCosmic rayMembrane potentialLimiterCapacity factorWeekMeasuring instrumentLightDayRoman calendarCar seatSpare partNebelkammerMachineMagnetspuleAlpha particleBahnelementMagnetic momentGameWearSheet metalLungenautomatSpantNuclear physicsWill-o'-the-wispAntiparticleCatadioptric systemAmplitude-shift keyingBand gapWeather frontPaperSteinmetzNeutronenaktivierungAutumnOrder and disorder (physics)Field-effect transistorElektroinstallateurCocktail party effectGasPaintQuantumBook designRailroad carSerientor-Sampling-LeitungPower (physics)Model buildingNeutronTrimmenDrehmasseMetreMagnetic coreGunSpectrographAngeregter ZustandMaterialSpaceflightSelectivity (electronic)Shock waveRemotely operated underwater vehicleContinuous trackKey (engineering)Cylinder headDyeingRutschungDesertionSwitcherFlightToolParticleTelephoneCounter (furniture)Sewing needleRedshiftStagecoachMusical developmentTransmission (mechanics)Water vaporStarAccelerationFACTS (newspaper)Hot isostatic pressingGalileo (satellite navigation)Communications satelliteSteckverbinderFunkgerätFeltField strengthClub (weapon)MicroscopeSpeckle imagingTypesettingOptical illusionElectric generatorNetztransformatorMinuteSnowSource (album)Formation flyingForgingContactorFaserkreiselHandwagenElectric motorMarble sculptureFiling (metalworking)MultiplizitätCollisionHydrogen atomIntensity (physics)SchalttransistorUniverseVoltageElectric currentStandard cellCapital shipSilveringOpticsNoise figureThermometerMagnetCartridge (firearms)Absorption (electromagnetic radiation)Effects unitGloss (material appearance)IceSea breezeSeries and parallel circuitsAlcohol proofPionNuclear reactorGamma raySurface acoustic waveLinear motorBackpackInfraredElectrostatic generatorFermionCERNGirl (band)Nuclear powerFoot (unit)KopfstützeDielectricProjectileBeta particleCoherence (signal processing)Coulomb's lawScale (map)WolkengattungFire apparatusPickup truckSpecific weightSpectroscopyRoll formingPlanetary boundary layerHyperbelnavigationTongue and groovePencilX-rayStonewareWoodNuclear transmutationPlane (tool)Uran-238FlorettSummer (George Winston album)Neutron sourceBuick CenturyIonisationskammerMuon
Transcript: English(auto-generated)
00:22
My name is Hern, I am here on the second floor, but it is the first in my own way to speak. I have the opportunity to speak German. I am very happy to see my German friends, who speak English very well.
00:44
Only all of you know how Italian I speak in English is. Next, I shall now continue in English, and the subject of my talk is not physics, strictly speaking,
01:03
but the interesting phenomenon of the resurgence of physics in Italy in the 1920s. Physics in Italy has had very great oscillations. It started with a cosine curve, namely with one at the beginning,
01:24
because of Galileo, whom you have already seen. The first slide, please. That's Galileo, and here I will also show you some of his apparatus and his publications.
01:51
Next slide, please. That's the essay, it's the first book in which physics experiments are described.
02:03
And it's the essay of the experiences, natural experiences, made by the Accademia Alcimiento. The next slide will show you the instruments, some of which are still well preserved.
02:21
You see these are sort of thermometers. The one on the left curling all over is a thermometer, and there are barometers, and such experiments in which you still see the Renaissance art. You see much more art than you would see in a modern experiment.
02:41
After Galileo, the curve sank down, mainly because of what happened to him, and physics traveled to northern countries, mainly England and Holland, to practically disappear from Italy until we have a second big maximum
03:08
at the time of Napoleon through the work of Volta. This work is almost incredible if you read it.
03:21
You find out at the end of the 18th century with rather primitive systems, a man measuring Volta potentials, potential difference between two metals, a thing which would be not quite easy even today.
03:41
Volta was a very, very great man with a powerful mind, but very few mathematical knowledge, very little mathematical knowledge. He was able to disentangle from the Galvani frog to the battery,
04:06
which is a tremendous achievement, and he reached that when he was about 55 years old. The next slide will show you not Volta because I can't find it,
04:21
but some of his experiments are the most famous one, which he showed to the French Academy at the time of Napoleon in 1800. You see some electrostatic experiment, a system by which he built what we would call nowadays an electrometer, and this electrometer is calibrated,
04:47
and so we can know today what was the scale involved of his machine, of his apparatus, and this is how we know what he found for contact potentials.
05:01
But his greatest achievement, the greatest of all, is the passage from the frog of Galvani to a battery, you see it there, which was the first apparatus able to give what we call an electric current of some intensity.
05:24
There were electrostatic machines before him, but the intensity they gave was so small that not much could be done with them. Volta reached this apparatus with 55 years old.
05:40
He became world famous. He was recognized all over France, England, and all countries, but somehow the utilization of his great discovery escaped him. Perhaps he was tired, he was perhaps a little old, and the discovery of electromagnetism,
06:03
the discovery, the new electricity, which was made possible by his battery, was not his work. Furthermore, Volta left no pupils in Italy. I don't know why a possibility is that his limited knowledge of mathematics
06:25
prevented him from communicating his ideas in a coherent fashion. Volta himself had very clear ideas about potential capacity, old notion of electrostatics, quite a few of electric current, in a quantitative way,
06:44
but not having a mathematical language, it was probably very difficult to communicate, somewhat similar to what happened to Faraday, who had to find Maxwell to understand what he really had in mind. The followers of Volta, there was about that time another great physicist in Italy,
07:11
and that was Avogadro. The next slide will show you Avogadro, who discovered Avogadro's Law in 1811.
07:22
I don't know whether Volta recognized the importance of Avogadro's Law. Volta had been, in addition to an electrician, a pretty good chemist, and experimented with gases.
07:42
So he was well in a position to understand Avogadro's Law, but I don't know whether he really did or paid any attention to it. You have to remember also that he was quite aged when Avogadro enunciated his Law. After that, in Italy you find some distinguished physicists,
08:08
but of little importance in the mainstream of physics. I could give you names, persons like Nobili, Meloni,
08:20
who was one of the earliest students of infrared radiation. He made quite valuable things, but they have more or less been forgotten or have been absorbed in the much more refined,
08:40
successive knowledge of experimental physics. Mossotti made a law on dielectric constant, which is probably still taught in school and bears his name, but when everything is said and done, there isn't much,
09:01
especially if you think that the contemporaries of these people were Ampere, Faraday, Fresnel, Helmholtz, and people like that, the real founders of classical physics. Now, there is this very big gap between Volta
09:24
and the resurgence of physics about 100 years later. The reasons for this are not clear, at least not clear to me. Some people say that it had to do with the political situation,
09:41
with the great effort that Italy had to make to reunite the nations and form a coherent kingdom of Italy. That absorbed many of the intellectuals and quite a bit of strength. Other people point out to the relatively backward stage
10:04
of industry and technology in Italy. Some people have advanced Marxian reasons. I think that none of these explanations are very satisfactory. For instance, one can say that industry was backwards in Italy,
10:28
but the best things that were made in Italy were in technology. The study of electric motors and transformers and then, of course,
10:41
Marconi, all these really owe very, very much to Italian contributions. The dynamo was invented by Pacinotti and shortly thereafter by Siemens. The system of transmission of energy is, to a great extent, the work of Galileo Ferraris, at least on the theoretical side.
11:03
And everybody knows the contribution of Marconi to radio communications. Furthermore, in that time, in Italy, there was quite a strong mathematics. There was not much chemistry, except Avogadro, who you see then,
11:25
and later, about 1860, Cannizzaro, who was a follower of Avogadro, and who is a man who really understood the importance of Avogadro's law for chemistry.
11:43
He made big propaganda for Avogadro's law at a congress in Karlsruhe around 1860, and we have testimony of people like Mendeleev and Lothar Meyer and so on, who say, now that we have heard Cannizzaro,
12:03
we have really understood the importance of Avogadro's law. But there was not much in practical chemistry. On the other hand, there was quite a flourishing school of mathematics,
12:20
which started around 1850 or 1860, and it had Beltrami, and then later, Volterra, and ultimately culminated with Levi-Civita, Severi, and other people, who are well known to every student of mathematics.
12:41
So there was strong mathematics. Now, there was no physics. If I were to mention to you the name of the Italian physicist, that wouldn't mean anything at all. You wouldn't know who they are. And it is in this sort of desert, cultural desert, that Fermi was born.
13:07
However, I want to anticipate a little. You will see that although Fermi had a very great part in the development of physics in Italy, he was not the only one. He was an important element, but there were also other centers, as you shall see in a moment.
13:23
Now, Fermi was born in 1901, and he was essentially self-taught. Now, we have his notebooks, and you can see from the notebooks that it would be very difficult to find a better teacher of physics than Fermi himself,
13:41
Fermi teaching physics to Fermi. In an admirable selection of material, it is really a question which turns me how a person who was 16, 17, 18 years old could, with infallible judgment, find out what was important and what was not important in physics.
14:05
This is really astounding. Well, he got his degree around 1923 working on relativity, on general relativity. Now, why general relativity was well known in Italy?
14:26
It was well known because of the contributions mainly of Ricci Curbastro indirectly and Levi-Civita quite directly. The next slide will show you Einstein.
14:41
Einstein, you see, visiting Bologna and speaking with a mathematician there, quite a distinguished geometer in request. And there is a very interesting and fascinating correspondence between Einstein and Levi-Civita in which Einstein is struggling to learn tensor analysis
15:02
and Levi-Civita, who was one of the creators from the mathematical side, discusses lots of equations and whether a thing was really a tensor, was not a tensor, and things like this. There is quite a big correspondence. It is for this reason that relativity was known in Italy
15:25
but was known only to the mathematicians, not to the physicists. Fermi, who was a rather powerful mathematician himself, started his earliest work in relativity by finding a theorem of tensor analysis
15:43
which is still well known to the people who work in this field. He also started as a student to make experiments in a rather primitive way with X-rays. When Fermi got his degree from Pisa, he came to Rome
16:02
and went to talk to a Professor Corbino who is a very pivotal figure in the whole story and it's a very remarkable man. Corbino was a Sicilian, an extremely smart person.
16:23
He was Professor of Physics at Rome, had done some important physics but nothing extraordinary, mainly on magneto-optics. He was a very sharp judge of men, very able to distinguish people,
16:43
and he had a burning ambition, namely to bring about a resurrection of physics in Italy. The next slide will show you Corbino. This is Fermi, 24 years old or 22 years old, when he arrived in Rome.
17:05
This picture was taken by his friend Persico, who asked him some question and very typically Fermi pulled out a pencil and a little piece of paper and said I'm going to calculate the answer and then he took the picture.
17:20
The next one will show you on the right Corbino. The man in the center is Sommerfeld who should be well known in Bayern and on the right is Millikan who should be well known to the Americans at least.
17:43
This picture is taken in Rome. Now Corbino, very unselfishly and with great ability and great intelligence, decided that Fermi was an instrument by which physics could be resurrected in Italy
18:04
and he did everything to facilitate Fermi's work. First he tried to find him a chair, a physics chair. There were no chairs of theoretical physics in Italy.
18:20
They didn't exist. It was a subject matter which was not contemplated by Italian university. There was mathematical physics and that was intended of the classical mathematical physics of the type of Volterra, of also Levitivita, but certainly each was never mentioned.
18:43
And Corbino who had a sharp tongue used to say, well, your mathematical physics is the theoretical physics of 1830, of 100 years before. He succeeded in appointing, he tried to get a job for Fermi, but at first he had difficulties.
19:08
In the meantime, Fermi discovered the Fermi-Dirac statistics and so became pretty well known all over.
19:20
The next slide should show you the Appanisperna, which is the institute where most of this work in Rome occurred. I see that some in the audience have also been there at that time more or less. And the next one will show you Fermi, Heisenberg, and Pauli on the Lake Como in 1927.
19:49
This was a rather epical moment because, first of all, there was an international conference in physics in Italy and it became apparent in it
20:01
that Fermi was the voice through which Italian physics could speak. There was practically no other one. And one saw all these young men, wonder children, Heisenberg, Pauli, and so on, talking to each other and explaining the mysteries of the new quantum theory.
20:26
With this, it was possible to start to establish a school in Rome. And by a series of lucky accidents, we met personally. For instance, I had known Fermi a few years earlier when he was just out of school.
20:46
I heard him giving a talk in Rome and it was apparent from the way he spoke that this man knew physics much better than anybody else I had ever heard. I myself was very much interested in physics,
21:00
but there was no way really of learning modern physics. I read books myself in which I found Einstein theory of specific heats, black body theory, and so on, and nothing of that kind of stuff was heard at school. Each was never mentioned.
21:21
Now, after me, Amaldi joined very soon, and I was a close friend of Ettore Majorana, who was my schoolmate, and I told Majorana to come to us and study physics.
21:43
And even more important, Rossetti was there, who had been a schoolmate of Fermi, was a superb experimenter, and in the hopes of Corbino would have done for experimental physics pretty much what Fermi did for theory.
22:04
In this way, we established a small group in Rome who worked mainly in spectroscopy. See, it was relatively easy for us to learn theory. First of all, because Fermi could teach it to us, and Fermi could read it.
22:20
He would read a paper of Schrodinger and tell us what it said and teach us quantum mechanics. He had great difficulty, I must say, in understanding the papers of Mr. Dirac, although he worked hard on them, and finally, he would also tell us what he read there.
22:44
We just had thus become a proficient school in atomic physics and spectroscopy. Now, I told you that Rome was not unique. In fact, similar development, but in an entirely different field,
23:02
were occurring in Florence, where the activity was centered on cosmic rays. In Florence, there was no Fermi. There was not a person, an overwhelming personality, but there were very able people like Rossi and Occellini and Bernardini.
23:26
All three, in later work, became very famous and very distinguished, mainly in cosmic rays. Now, also in Florence, there was no Corbino,
23:43
but there was a professor of physics who was helpful. He was not as wily and as unselfish as Corbino, but certainly he helped. The problem of money was not very important,
24:00
because physics at that time was quite simple. We did experiments which didn't cost anything, and we tried to replace by thought what we didn't have in money. So our operators, you will see later, were always extremely simple.
24:21
Our techniques were rather primitive. We were not skilled experimenters. On the other hand, we had a good command of theory and a good knowledge of the relation between theory and experiment. You see these two autochthonous centers, Florence and Rome,
24:42
which were not completely independent, because a person from Rome, Persico, who was a close friend of Fermi, was also appointed professor of theoretical physics. He was the second professor of theoretical physics in Italy, the first one being Fermi, and went to Florence.
25:02
So there was a continuous interchange. And then there was a little activity also in Turin, not much. But at least Florence and Rome were operating. We come thus to the epoch of the completion of quantum mechanics
25:23
around 1928, 29, 30, at least completion of quantum mechanics in its present form. And it became very clear, we had very clear feeling that there was a sort of closure of the field of atomic physics
25:46
and of non-relativistic quantum mechanics. The next step had to be nuclear physics, namely the next big discoveries would come in nuclear physics.
26:03
I will show you first a slide showing Rossi. Next slide, please. There you see Rossi at the right, Amaldi, who was in Rome, and I, but this is taken years later when we were already somewhat famous,
26:21
but I don't have an earlier one. And the next one will show you, the next slide, please, will show you Occellini at the right with Powell. Of course, Occellini discovered the pi mesons together with Powell and Lattes and other people.
26:42
The knowledge, the feeling that we had finished, that atomic physics, non-relativistic quantum mechanics, and so on were not completely completed but had reached a sort of stage of maturity, was very clear in us, and then we had to do something else.
27:06
And we had absolutely no doubt that the next step would be nuclear physics. So we made a conscious effort around 1930, 1931, to start learning whatever was known in nuclear physics.
27:23
We studied carefully Rutherford's book, and we started to build equipment that could be used for nuclear work. We didn't know what this work would be, but we started building a cloud chamber, counters, a gamma ray spectrograph, and various things of this type.
27:46
Then all this is not hindsight. I mean, it can be documented because there are speeches of Corbino in which he sets out a sort of prophecy of what physics would be in the next 20 or 30 years,
28:03
and this speech is uncanny in its farsightedness. It's quite amusing to read, although it's in a very difficult Italian, I must say that. The next step was to try to have contact with somebody
28:30
more skilled in nuclear physics. And Fermi had become by that time a big shot in the Italian Academy, and it was possible to call a small conference in Rome,
28:44
unfortunately at the very wrong moment, because the conference was called in 1931, just before the discovery of the neutron. But I will show you in the next slide the persons. Next slide, please. The person who were there. Can you focus it a little better?
29:03
Well, you can see here, Otto Stern, Bleckett, Mott, Debye,
29:20
Richardson, Millikan, Compton, Madame Curie, Marconi. Marconi was there because he was the president of the Academy, not that he had anything to say. Corbino, Niels Bohr, Ashton, Bote, Rossi, Sommerfeld, Goudsmit, and here behind,
29:44
Fermi, Persico, Ehrenfest, and lesser lights, which I will omit, mainly Rossetti here, and Ellis. This is Ellis. Now, with a small conference like this,
30:02
we tried to learn everything that could be learned, but as I say, unfortunately the time was poorly chosen. In 1932, there was the wonder year of physics with the discovery of the neutron, of the positron, of deuterium,
30:22
the anomalous magnetic moment of the proton, and everything came in that year. As you probably know, the discovery of the neutron is quite complicated, and the Joliot, Curie and Joliot missed quite a few things.
30:41
They were somewhat unhappy because they really had bad luck and not much insight in what they were doing. Well, let me go in this order. A little later, at the end of 33,
31:04
there was a famous Solvay conference. I will not show you the slide of it because it has been shown so many times that I would be a little ashamed of showing you that slide again. But it was a memorable conference
31:20
in which all the important people in nuclear physics met, and it was after the discovery of the neutron, after the discovery of the positron, and so there was much to discuss. In this connection, I would also say that you heard yesterday from Merzbauer
31:41
about the neutrino, and I don't know whether that was the occasion, but certainly a little before, the neutrino, which had been invented by Pauli, was christened by us in Rome as neutrino, which means small neutron, as distinguished from the big neutron,
32:01
which was the neutrone. In this conference, many ideas were in the air, and soon thereafter, weeks thereafter, Fermi came out with the theory of beta decay, which is more or less a theoretical masterpiece.
32:24
But more important, or equally important, Curie and Joliot discovered artificial reactivity early in 1934. In fact, already, if you read the reports of the Solvay Conference of 1933,
32:42
you see how near the discovery of artificial reactivity was. There are remarks by Francis Perrin, which really almost tell you, but have you looked that there is no artificial reactivity? It doesn't say so in so many words, but by hindsight, one can see it.
33:00
The discovery of artificial reactivity produced a tremendous impression all over the world, and in Rome, we felt that this was a sort of godsend. We had prepared all the tools for doing nuclear physics,
33:23
and this was something to work on. And the first idea, which is quite simple but very important, was to use neutrons instead of alpha particles as projectiles.
33:41
The Curie and Joliot used only alpha particles. By using neutrons, which are not repelled by the Coulomb force, you could attack not only the very light elements, but also heavy elements. Of course, the neutrons were fewer in numbers, but you could compensate by being fewer
34:04
because they were the penetrated matter and could be stopped only by nuclear absorption. In other words, it's almost a way of making all elements light as far as nuclear absorption is concerned.
34:20
With this, we started a systematic bombardment of all elements until and then proceeding. Fermi was a very systematic man. He started with hydrogen, helium we didn't have, lithium and so on. He never found any activity until he arrived to Florin.
34:42
You see, but since he was determined to persist until he found the phenomenon, the first eight failures didn't scare him. At the time then, he asked Amaldi and me and Rossetti to help in this work
35:00
because it was clear that it was an overwhelming amount of stuff to be seen and worked on. And this is one of the very first team works, although it was a ridiculously small team by present standards. We were five, but five persons was considered
35:22
a very great number, all working together. We bombarded all the elements, including uranium and thorium, where we found very strange phenomena which we misinterpreted. First, we couldn't understand them.
35:42
Then we interpreted them as formation of transuranic elements and then we got into troubles, but I must say that Hahn and Meitner, who were great experts in the Korean Joliot and everybody who bombarded heavy elements,
36:02
remained blind to what was really going on for several years, as you shall see in a moment. The vacations of the summer of 1934 found us in... Well, Fermi went to South America, Amaldi and I went to Cambridge,
36:22
where I saw, again, several of the people who are in the audience here, including Professor Kapitsa. Then, when we came back to Rome, we started to find phenomena which were completely ununderstandable, namely, if you were to activate a foil of silver
36:43
on a table, you would find a certain activity. You would repeat the same experiment with the same source, the same foil and everything else, but on another table, and you would find a completely different result. This was a puzzle for quite a bit until, finally, we discovered that
37:03
the important thing was that the table was of wood and the other table was of marble. And then, what was holy about wood, wood contained hydrogen, then we put paraffin, and we found out that one could slow down the neutrons by multiple collisions,
37:23
and that, contrary to all expectations, slow neutrons were much more efficient in producing transmutations than fast neutrons. This was something that nobody knew or nobody expected. There is a whole study on how this discovery was made, but this is the principle thing.
37:43
I want to know at what time... Oh, I have five minutes more, seven minutes more. The discovery of slow neutrons was obviously of industrial importance,
38:02
and Corbino asked us immediately to patent it, saying, I don't know what it will be used for, but there is no doubt in my mind that this is going to be a big, practical thing. Mainly what we thought at that time was the formation of radioactive isotopes.
38:21
We didn't know, of course, of nuclear energy. The next slide will show you Rossetti and Fermi in academic garb about that time, about 1933, something like this.
38:41
This is Rossetti, and this is Fermi. I am the other one. The next one, next slide, please, will show you our great accelerator and our great neutron source. As you see on scale, this is it. All the work was done with apparatus similar to this,
39:04
with neutron sources similar to this one. In fact, I have one of them still because they were filled with emanation, which decayed every week, and you had to make a new one. The next slide shows you...
39:23
You see how simple our apparatus was. This is an ionization chamber. And it was our main instrument. It was so important to us that we called it, jokingly, the signum Romanum, or the Roman sign,
39:42
because wherever we went, we would build one like that. In fact, this one is the Berkeley edition of the Roman sign. But there is one in Ann Arbor. There is one at Columbia. There is one in Palermo. There is one in Rome, and so on. They're all over like the media stone of the Romans.
40:05
With these simple apparatus, it was possible to make very precise measurements. And it was used to develop the theory of the slow neutrons and their motion,
40:22
slowing down, and everything else, which became later of very great practical importance for making reactors. Now, this is 1934, 35. By that time, the political situation in Europe
40:43
was deteriorating very badly. Italy was embarking on the Ethiopian war. The Spanish war was imminent. In Germany, there was Hitler. And we all felt extremely uneasy
41:01
and very conscious of impending catastrophe. Thus, external forces destroyed our group. They destroyed it because Rossetti said, I have enough of this Europe. I will go to America, and went to America.
41:22
I was promoted and became professor in Palermo, but I was not in Rome anymore. Pontecarlo, who had joined us, went to France, and so on and so forth. There was a sort of destruction of the group.
41:41
The only one who remained in Rome were Fermi and Amaldi. But Fermi himself was becoming very dubious. He had had previous offers to go to Zurich and to various other places, and had always renounced or declined,
42:02
mainly at the instances of us, of his friends. But when Mussolini discovered the antisemitic laws, he copied Hitler. Then it was too much. It was 38.
42:20
And by that time, the whole place collapsed. Fermi came to America. I was at that time in America and remained there. Rossetti was in America. Rossi went through Denmark to America.
42:42
Occellini went to Brazil. And practically, Majorana killed himself. And practically, the only person who remained in Italy was Amaldi, who for family reasons and for various reasons didn't move.
43:01
Now, what is most remarkable is that in spite of all this, physics was not destroyed in Italy. There was a tremendous number of linears with extremely difficult conditions and situations. But there was also a great will to do something
43:23
and to survive. They reduced all the operations to cosmic ray alone. They concentrated them all practically between Rome and the little Florence, but mainly Rome. And they had luck because they could make the experiment
43:40
of conversi, pancini, and Piccioni on the mu meson and pi meson, which was very important. And then, shortly thereafter, Powell and the Inford people in England developed sensitive emulsion. Occellini from Brazil came there, saw the situation, and helped to use these emulsions
44:04
or persuaded them to use these emulsions with cosmic rays, bringing about the great discovery of the pi meson. Emulsions were very cheap. They required big manpower,
44:20
but they were cheap and simple to use. And thus, immediately after the war, Italy found itself in not too bad a position because cosmic rays come everywhere. They could buy a pack of emulsion. They could get some microscope. And they studied, and they had lots of girls
44:40
to measure the emulsions. And so cosmic rays and high-energy physics became the main type of Italian physics for a few years. On the illusion that this was the cheapest type of physics you can imagine. I mean, that was, of course, before the accelerators.
45:02
Then came the accelerators, and Italy joined CERN. In fact, they were among the promoters of CERN. And ever since, Italian physics has survived on a foot of equality with all the rest of good European physics.
45:25
It isn't anything extraordinary, but it isn't in no way worse than what you find in many of the other countries. And this is how Italian physics was re-established. Thank you.