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Nobel Laureates

Luis Alvarez

1968 Nobel Prize for Physics

Presentation of Award
Acceptance Speech
M. Alvarez, Address to the University Students on the Evening of
December 10, 1968

Biography Submitted by Dr. Alvarez to the Nobel Committee

• Presentation of the 1968 Nobel Prize for Physics

Professor S. Von Friesen of the Royal Academy of Sciences.
Milt White beside the 60-inch cyclotron with which Alvarez showed the stability of helium-3.
Your Majesty, Your Royal Highnesses, Ladies and Gentlemen.
The science of physics has as its function the study of energy in all its forms. Einstein observed that matter, or mass, is one of the forms in which energy manifests itself. This fact was established experimentally 35 years ago, when it was discovered that high-energy electromagnetic radiation was capable of producing pairs of electrons, one with positive, the other with negative charges. It has since been possible to produce other similar pairs. for example protons and antiprotons. These newly-created particles are stable and, if left undisturbed, can exist indefinitely. Unstable particles can also be produced, however. These disintegrate rapidly into other particles and, passing through one or several stages, revert to stable forms or develop into other forms of energy. Many such new particles have been discovered and studied during the last two decades. They are so minute that it is impossible to see them; they can only be identified by the tracks they leave behind them as they move. The scientist must behave like the hunter, who determines the identity and behaviour of his quarry by studying tracks left in the snow.

The new particles are normally produced with the help of the great, new accelerators which cause the particles to move at very great speed. This has the advantage that, although the life-span of the particle might be as little as a ten-thousandth part of a millionth of a second the track acquires a length of several centimetres.

Luis Alvarez with Bubble Chamber display built in Berkeley, California.
One could, however, suspect the existence of particles with considerably shorter life-spans and with such small track-lengths that they are impossible to measure. In this case one is obliged, instead, to study the tracks of their disintegration products and the tracks of the reactions they produce in collision with other particles. The pattern of tracks thus becomes very complicated; the correct interpretation of what actually occurs requires acute powers of discernment and a particularly advanced experimental technique. It is in this field that Professor Luis Alvarez has made the contributions for which he is today being rewarded.

He has with insight and determination developed the bubble-chamber, invented by the Nobel Prize winner in Physics, Donald Glaser, into an invaluable instrument for this type of investigation. Alvarez' bubble-chamber contains many hundreds of litres of hydrogen, reduced to a temperature of minus 2500deg.C, which thus becomes fluid. When the particle passes through the liquid, it is warmed to boiling point along the track it leaves. In the wake are a trail of bubbles that can be photographed whilst still very small. The photographs are able, in this way, to reproduce accurately the path of the particle. Because the chamber contains only hydrogen, it is evident that all reactions must occur with hydrogen nuclei, protons. This considerably simplifies the interpretation of the phenomenon. The cost of this instrument, capable of producing about a million photographs annually, was two million dollars.

Luis Alvarez about 1938, just before his work leading to the identification of helium-3.
The photographs must be studied and measured with great accuracy. In order to carry out this enormous task, Alvarez and his assistants have constructed a series of more and more delicate automatic scanning and measuring instruments capable of transferring the information from. the photographic film into a state suitable for treatment by computer. In this field, too, Alvarez has made contributions of a pioneering nature.

With the establishment of the hydrogen bubble-chamber, entirely new possibilities for research into high-energy physics present themselves. Results have already been apparent in the form of newly-discovered elementary particles. The first, very short-lived, so called, "resonance particle" was found in 1960. Since then there have been a whole series of discoveries made by Alvarez' group in Berkeley, California and in other laboratories where Alvarez material is being used or where his methods and programs are adopted. Practically all the discoveries that have been made in this important field of high-energy physics have been possible only through the use of methods originated by Professor Alvarez.

Dr Alvarez.

Your contributions to physics are numerous and important. Today our attention is focused on the outstanding discoveries which you have made in the field of high-energy physics as a result of your far-sighted and bold development of the hydrogen bubble-chamber into an instrument of great power and high precision and of the means of handling and analysing the large quantities of valuable information which it can produce.

On behalf of the Royal Swedish Academy of Sciences I extend to you our warm congratulations and now ask you to receive the Nobel Prize from the hands of His Majesty the King.

© the Nobel Foundation 1969

• Acceptance Speech

Dr. Luis Alvarez, shortly after being awarded the 1968 Nobel Prize in physics, with Bubble Chamber display.
Your Majesty, Your Royal Highnesses, your Excellencies, Ladies and Gentlemen:
I learned much of the physics I know from two men who preceded me to this banquet table--Arthur Compton and Ernest Lawrence. Because Ernest Lawrence's award came in the war years, I had the unusual opportunity of attending his Nobel Prize presentation ceremony. The Swedish Ambassador to our country came to California to represent his King. I remember the pleasure and satisfaction I had in hearing my friend and Laboratory director mention some of my own work, that had contributed in small measure to the broad picture of Ernest Lawrence's great influence on modern physics.

One indicator of Ernest Lawrence's influence is the fact that I am the eighth member of his laboratory staff to receive the highest award that can come to a scientist--the Nobel Prize. I am deeply grateful to the Royal Swedish Academy of Science for judging me worthy to be associated in this way with my esteemed colleagues, and with the other distinguished physicists who have sat at this table in years past.

I am particularly happy that a number of my young colleagues are here tonight to share with me the great recognition that our joint efforts over the years has just been accorded. We all appreciate that the Prize must be given to a person, rather than to a group, but we are all honest enough with each other to understand just how much of a group effort our work really was. I was afraid that this knowledge might be a sort of private secret between us, so I was delighted to hear my old friend Sten von Friesen refer this afternoon to "a whole series of discoveries made by Alvarez' group in Berkeley". That is the way I remember it, and because of my previous experience at the ceremony in Berkeley almost thirty years ago, I feel particularly close to my colleagues assembled here tonight.

Dr. Luis Alvarez taken in Building 46, July 1, 1966.
In addition to my teachers and my colleagues, I would like to mention one other person who shares equally in the responsibility for my presence here tonight. Janet Landis came to work in my group in the summer of 1957 when our first bubble chamber was churning out its earliest pictures. She scanned and measured the photographs, she operated the computer, and she later trained and supervised the people who did that work. Almost exactly ten years ago, she left the Laboratory to become my wife. Since then, she has rearranged our living room every Monday night to entertain forty of my young associates who arrive on schedule for our weekly seminar. She has provided the warmth and understanding that a scientist needs to tide him over the periods of frustration and despair that seem to be part of our way of life. I know it is an old Swedish custom that a man must Skål his wife at a banquet under penalty of dire consequences for failure. So with your permission, I will now Skål my Jan.

© the Nobel Foundation 1969

• M. Alvarez, Address to the University Students on the Evening of December 10, 1968

Students of Stockholm: I am pleased to have the honor of speaking to you briefly tonight. Before I left Berkeley last week, several of my friends who had attended this ceremony told me that one of this year's Laureates would be given the honor of addressing the assembled students, but they all said I could forget about it--one of the younger men would be chosen. So when I was singled out, I tried to reconcile this fact with what my friends had told me. I then remembered there are many measures of age, for example, the number of years a person has lived, the useful diameter of his arteries, and the activity of his brain cells. The only criterion I could think of that could label me as the youngest Laureate was that I have the youngest child--my wife and I had to leave our one year old daughter at home with her grandmother.

Before replying to the speech that your representative has just given, I must say that I am highly skeptical that you really are students. I am from Berkeley, California, so as I look at you in your formal evening clothes, you can appreciate how disturbed I am to see no men in long hair and beards, and to see no girls in secondhand Army shirts and patched trousers. But in order to get on with the program, let me assume for the moment that you really are students.

The problems of which you have just spoken are among the most pressing the world now faces. and it is clear that my generation needs the help of yours in solving them--we haven't done very well by ourselves. In the few minutes left for my reply, I would simply like to say that the problems you mention are the most difficult ones I know, and there are no simple solutions.

People often say to me, "I don't see how you can work in physics; it's so complicated and difficult." But actually, physics is the simplest of all the sciences; it only seems difficult because physicists talk to each other in a language that most people don't understand--the language of mathematics. The thing that makes physics simple is that when we make a simple change in a system, such as adding a little heat, we can easily predict that the whole thing is going to get warmer. We can even treat more complicated systems, like the famous Swedish Electrolux refrigerator, and correctly predict that if we add heat at one place, the cooling unit will start to make ice cubes.

But in the case of an infinitely more complicated system, such as the population of a developing country like India, no one can yet decide how best to change the existing conditions. You spoke of your concern, which I share, for the people of the lowest economic status, whose birth rate is highest, and who are most clearly faced with the prospect of starvation. But I am afraid that you have not properly identified the cause of the famine and starvation. In my opinion, the present situation is caused not by a high birth rate, but what we should call "death control." It used to be that infant mortality was terribly high in India, but this has recently been arrested by the application of the great medical discoveries, made largely in the Western World. So it is not the high birth rate you mentioned that is the root of the troubles, it is the unnatural survival of so many children to an age when they become major food consumers--a survival made possible by the well intended efforts of good people who hate to see young babies die needlessly.

Would you have been wiser than we have been, if you had had your hand on the "control knob"? Would you have turned the control, as we did, to the position labeled "cut down infant mortality", or would you have been wise enough to foresee the starvation that would be brought to these same infants and others as they grew older? You would probably agree with me that the proper answer to the evils brought about by "death control", is birth control, to restore the population balance. But the religious and ethical problems faced by those who try to introduce birth control into certain cultures are beyond the comprehension of those of us who deal in the simple problems of physics.

One more illustration will show how difficult it is to decide whether we are helping or hurting humanity when we do something that is very obviously humane. Most women today are just barely able to give birth to children, in what is a terribly painful experience, if unaided by drugs. The reason women are able to endure childbirth is simply that those who couldn't do so in the past, died in childbirth, and didn't pass this inability on to their daughters. But what happens today? No doctor will let a woman die in childbirth if he can prevent it with a Caesarean operation, and you and I would do the same thing. But what is this doing to our hard-won genetic heritage? This illustration occurred to me simply because one of my friends owns a rare kind of small dog that has been bred to the point that all births must take place by Caesarean section. If we do the same thing to our human population--and we are certainly moving in that direction as a result of our feelings of personal humanity, what will happen to the human race if we face a natural disaster that would remove the possibility of modern medical care. We are not free from future global catastrophies such as an ice age, a period of intense volcanic activity that could blanket the atmosphere in dust, or a melting of the Antarctic ice cape that could flood most of the land on which we now live.

I am not trying to be a prophet of doom; I have merely given you two examples of the difficulties that will confront you when you have the responsibility to make decisions that will affect the future of mankind. I wish you the best of luck and good judgment when that time comes. The world would be a much better place in which to live if my generation and those that preceded it had had more of those two essential attributes, good luck and good judgment.

© the Nobel Foundation 1969

• Biography Submitted by Dr. Alvarez to the Nobel Committee

Luis W. Alvarez
Portrait of Luis Alvarez, 1962.
Luis W. Alvarez was born in San Francisco, California, on June 13, 1911. He received his Bachelor of Science Degree from the University of Chicago in 1932, a Master of Science Degree in 1934, and his Ph.D. in 1936. Dr. Alvarez joined the Radiation Laboratory of the University of California, where he is now a professor, as a research fellow in 1936. He was on leave at the Radiation Laboratory of the Massachusetts Institute of Technology from 1940 to 1943, at the Los Alamos Laboratory of the Manhattan District from 1943 to 1945.

Professor Alvarez is a member of the following societies: National Academy of Sciences, American Philosophical Society, American Physical Society, and American Academy of Arts and Sciences. In 1946 he was awarded the Collier Trophy by the National Aeronautical Association for the development of Ground Control Approach, an aircraft landing system. In 1953 he was awarded the John Scott Medal and Prize by the city of Philadelphia, for the same work. In 1947 he was awarded the Medal for Merit. In 1960 he was named "California Scientist of the Year" for his research work on high energy physics. In 1961 he was awarded the Einstein Medal for his contribution to the physical sciences. In 1963, he was awarded the Pioneer Award of the AIEEE, in 1964 he was awarded the National Medal of Science for contributions to high energy physics, and in 1965 he received the Michelson Award. Sc. D., University of Chicago, 1967; Sc. D., Carnegie-Mellon University, 1968; Nobel Prize for Physics, 1968.

Seven LBL Nobel laureates, posed in front of Ernest Lawrence's 37-inch cyclotron magnet. Left to right are Owen Chamberlain, Edwin McMillan, Emilio Serge, Melvin Calvin, Donald Glaser, Luis Alvarez and Glenn Seaborg. March 7, 1969.
Early in his scientific career, Dr. Alvarez worked concurrently in the fields of optics and cosmic rays. He is co-discoverer of the "East-West effect" in cosmic rays. In 1936, he joined the Radiation Laboratory at the University of California, and for several years concentrated his work in the field of nuclear physics. In 1937, he gave the first experimental demonstration of the existence of the phenomenon of K-electron capture by nuclei. Another early development was a method for producing beams of very slow neutrons. This method subsequently led to a fundamental investigation of neutron scattering in ortho- and parahydrogen, with Pitzer, and to the first measurement, with Bloch, of the magnetic moment of the neutron. With Wiens, he was responsible for the production of the first Hg198 lamp; this device was developed by the Bureau of Standards into its present form as the universal standard of length. Just before the war, Alvarez and Cornog discovered H3 (Tritium) and He3. (Tritium is best known as an ingredient of thermonuclear weapons, and He3 has become of importance in low temperature research.)

During the war (at M.I.T.) he was responsible for three important radar systems--the microwave early warning system, the Eagle high altitude bombing system, and a blind landing system of civilian as well as military value (GCA, mentioned earlier). While at the Los Alamos Laboratory, Professor Alvarez developed the detonators for setting off the plutonium bomb. He flew as a scientific observer at both the Alamagordo and Hiroshima explosions.

Dr. Alvarez is responsible for the design and construction of the Berkeley 40-foot proton linear accelerator, which was completed in 1947. Since that time, he has engaged in high energy physics, using the 6 billion electron volt Bevatron at the University of California Radiation Laboratory. His main efforts have been concentrated on the development and use of large liquid hydrogen bubble-chambers, and on the development of high speed devices to measure and analyze the millions of photographs produced each year by the bubble-chamber complex. The net result of this work has been the discovery by Dr. Alvarez' research group, of a large number of previously unknown "fundamental particle resonances".

[Dr. Alvarez died in 1988]

© the Nobel Foundation 1969

Ernest Orlando Lawrence Berkeley National Laboratory

Last modified Tuesday, 23-Mar-2010 14:44:48 PDT