Recognizing Achievements of Physics in Harvard In 1884, the first building in the western hemisphere designed solely for

research and teaching in physics opened its doors. This was the Jefferson Physical Laboratory, still existing in the north yard. (Gerald Holton, “How the Jefferson Physical Laboratory came to be,” Physics Today 37(12); December 1984.) A hundred years later in 1984 the anniversary was celebrated by a day of talks about the work that had been done which had made their unique contribution. That was followed by a celebratory dinner by the President in Memorial Hall. Many speakers talked about interesting history and there were several items of interest that could be formally recognized by some sort of plaque on the appropriate wall. Such a list was presented to the department but nothing was decided. Issues such as what, and maybe who

should be recognized, completeness, age and so on confused the issue. On the many occasions when potential Harvard undergraduates and graduate

students have visited they have been fascinated by this great history which a faculty member describes to them. We are proud of it. Maybe one should only recognize an event when the people are dead. This was the old fashioned way of proceeding following the precedents created by the canonization procedure in the Roman Catholic Church. But the modern American way is not to recognize a discovery or invention but to name the building after a wealthy donor, before anything useful has ever been done there. Indeed funding for the Jefferson Laboratory came from the descendants --the family of Thomas Jefferson Coolidge. This is recognized by a plaque on the 2nd floor of Jefferson Laboratory facing the entrance with a bust of Thomas Jefferson Coolidge just above the plaque. The department decided upon a compromise between the two positions. The department has recognized discoveries after the discoverer has retired. In the rest of this paper some of these discoveries are noted and the recognition plaque is described.

As is usual in such matters, delay was the decision and the for 25 years the only item that was recognized is the work of the lecturer Wallace Sabine in the main lecture room Jefferson 250. Inside the lecture room his plaque reads:

“Wallace Clement Sabine, professor of physics in Harvard, made in this room many of the experiments through which within the years 1895-1914 he created the science and the art of architectural acoustics.”

With undergraduate students Sabine studied absorption of sound and brought cushions in at night from Sanders theater. These cushions became the standard unit of acoustic absorption for many years and one still exists in the museum of Scientific Instruments in Harvard University’s Science Center. He also used a special reverberation chamber in the basement of Jefferson Laboratory, above which can be read:

“Below here W. Sabine built a reverberation chamber used from 1896 to 1919 for his studies of architectural acoustics.”

Sabine’s papers are in a museum in Batavia Illinois, and a description of them was written by Dr. Leo Beranek. (Leo L. Beranek, “Wallace Clement Sabine and Acoustics,” Physics Today 38(2):44; February 1985.)

The next Harvard Professor recognized here is Theodore Lyman. The lines of the atomic hydrogen spectrum had been measured by Johann Jakob Balmer (1825-1898) and described by Rydberg. There was a gap: no one had measured the 2P -1S transition which according to Rydberg’s formula, would be a line of ultraviolet light. Lyman accepted the challenge of measuring these ultraviolet lines of the 2P to 1S transition. It is unclear to us exactly where this was done, or even when the first measurement of several attempts was made. However it’s importance is now almost universally recognized. The plaque just above steps to the basement of Jefferson Laboratory reads:

“Starting in 1906 in a basement room below here, Theodore Lyman measured the ultra violet spectrum of hydrogen (Lyman Lines) using a spectrograph of his own devising.”

Also in the beginning of the 20th century Percy Williams Bridgman began his work on physics at high pressures. This led to a series of papers. We recognize this as follows:

“Starting in 1905 P.W. Bridgman developed and used apparatus for studying physics at high pressures for which he was awarded the Nobel Prize in 1946.”

One of the first important theorists in Harvard University was E.C. Kemble who was one of the first theorists in the USA to understand the revolution in physics caused by the quantum theory firstly by Schrödinger and then by Paul Dirac in Cambridge, England. However we have no specific work by which to recognize him.

Starting in 1920 was one of Kemble’s graduate students John Hasbrouck Van Vleck, or just Van as he was affectionately called, went to Cambridge about 1927 and became a close friend of Paul Dirac and brought back Dirac’s ideas to the USA. Van showed how a 2-electron atom could demonstrate ferromagnetic properties in his Magnum Opus “The Theory of Electric and Magnetic Susceptibilities” (Oxford University Press, 1st edition; December 1932) recognized by a Nobel Prize in 1977. He later became Hollis Professor of Mathematics and Harvard and Dean of the Division of Engineering and Applied Physics (DEAP), now the School of Engineering and Applied Sciences (SEAS).. As a scientist he was always showing how two scientists describing the same phenomenon in different ways were really talking about the same subject. As one of Harvard’s greatest administrators, he built a bridge connecting the physics department and engineering so that one did not have to go out into the brutal February weather. He is recognized by plaques at the top of each entry to the bridge:

“VAN VLECK BRIDGE to PIERCE HALL, MAXWELL DWORKIN LAB”

And a smaller one on the side summarizing his accomplishments:

“John Hasbrouck Van Vleck (1899-1980)PhD Harvard 1922

Professor Harvard (Hollis Professor of Mathematics) 1934Hon DSc Harvard (Dean, Division of Engineering and Applied Physics) 1966

Nobel Laureate 1977In his life he built many intellectual bridges, as well as, this physical bridge.“

The scientist Edwin Land dreamed of having a simpler way of polarizing light than the Nicol prism that had been used for over 50 years. He designed a special plastic filter. The filter can be thought of as having long-chain molecules that are all aligned within the filter in the same direction. During the fabrication of the filter, the long-chain molecules are stretched across the filter so that each molecule is (as much as possible) aligned in say the vertical direction. As unpolarized light strikes the filter, the portion of the waves vibrating in the vertical direction are absorbed by the uncertain exactly when and where he produced the first such filter but his genius was recognized by Theodore Lyman, by then Director of the Physical Laboratories and our recognition on the wall of a laboratory in the 4th floor of Jefferson Physical Laboratory is as follows:

“In 1930 Edwin Land, an undergraduate, was given this room to develop his invention of Polaroid, later described in a colloquium in February 1932.”

Land never got his undergraduate degree and was always a little reticent about his work. He was, however later given an honorary DSc by Harvard for his lifetime work. Late in his career he founded the Rowland Institute of Science on the water front in east Cambridge. Land always admired the work of the physicist Rowland and wished to honor his memory. But the fact that the name ended in Land probably influenced his enigmatic choice. In 2002, after his death the Rowland Institute became a part of Harvard University

From 1880 until the 1940s phonograph records were on shellac disks. Attempts to record on vinyl disks were unsuccessful because the “needles” used to follow the tracks quickly destroyed the record surface. It became important in 1936 for the 300th anniversary of Harvard University. The proceedings were recorded on vinyl. The problem of playing them back was solved by Frederick Vinton Hunt and his graduate student Leo Beranek who devised a light weight phonograph pick up in a room on the 4th floor of Lyman Laboratory. We recognize this by the following:

“In this room FV Hunt and his student Leo Beranek built the first light weight phonograph pickup enabling long played records on vinyl.”

Dr. Beranek is probably the oldest living graduate of the department. We print here his photograph taken when he was 95 years old next to this plaque.

In 1940 Dr. Beranek was called by the federal government for war work. This is noted in this plaque on the ground floor of Lyman Laboratory:

“Between 1940 and 1945 on this floor and the basement Leo Beranek directed the Harvard Electro-Acoustics Laboratory for airborne sound research in World War II. It was the first federally funded research program at Harvard and at its height it employed 100 persons.”

This work was secret. Anyone had to pass security guards posted at the entrance to Lyman Laboratory. Over the years some $4 million (in 1940 dollars) was provided by the federal government and unlike today, Harvard did not charge any overhead. Let it not be said that Harvard did not support the war effort.

Dr. Hunt also put his acoustical skills at the service of the government. In the ground floor of Lyman Laboratory we recognize his work which began a little later:

“In this room FV Hunt in June 1941 started the Harvard Under Water Sound Laboratory for torpedo guidance and submarine detection before moving to Hemenway gymnasium in 1942.”

At the end of World War II both the Beranek Laboratory and the Hunt Laboratory had to close because Harvard did not want secret work any longer. Part of the Underwater Sound Laboratory went to Pennsylvania State University which did not worry about secrecy restrictions. Penn State was happy to have a fine laboratory which became the start of a fine scientific institution and both institutions gained by the deal.

Professor Howard Aiken was always fascinated by the 100 year old ideas of Babbage of building a digital computer that could modify its own program. The opportunity came in the 1940s. It was installed in the basement of Lyman Laboratory and was also a secret installation at first:

“In 1944 IBM and Professor H. Aiken installed here the “Harvard Mark I

Sequence Calculator” which may now be seen in the Science Center.”

But Harvard was changing its scientific directions from merely studying bulk properties of materials, to studies of fundamental units of matter. On the ground floor of Lyman Laboratory several discoveries are recognized:

“In 1937 in a shed outside this room, J.C. Street and E.O. Petersen used a triggered cloud chamber to see the decay of muons into electrons and thereby establish the existence of the muon. Later in December 1945 the same magnet was used by E.M. Purcell, H.C. Torrey and R.V. Pound in the first observation of nuclear magnetic resonance”

In September of 1934 Kenneth Bainbridge arrived in the Harvard Physics Department. He was known for two major items at Harvard. Firstly the construction of the first Harvard cyclotron and planning for the 2nd cyclotron, (described by Richard Wilson, a short history of the Harvard cyclotrons, HUP) but he was already known for his study of the mass energy relations with steadily increasing precision. Outside a room in the basement of Lyman is the plaque:

“In this room Kenneth Bainbridge built the last of a series of precise mass spectrometers with which he verified Einstein’s mass-energy relation E=mc2.”

Harvard physics was also moving to other fundamental directions. On the 4 th

floor of Lyman Laboratory the following plaque may be seen:

“On the balcony outside this room in 1951 H.I. Ewen and E.M. Purcell mounted a microwave horn and were the first to see the 21 cm microwave radiation from interstellar hydrogen.”

The microwave horn itself has an honored place in the Smithsonian institution in Washington D.C. But its photograph and caption thereon are next to the recognition plaque: “This horn antenna was used by Harold I. Ewen and Edward M. Purcell at the Lyman Laboratory of Physics at Harvard University in 1951 for the first detection of radio radiation from neutral atomic hydrogen gas in the milky way at a wavelength of 21 centimeters.”

There were two interesting items of note. The horn was constructed with a total budget of $500 compared with the multimillion budgets of today. Secondly it was of immediate interest as noted by the proceedings of an international conference in 1951 in Holland. (H.I. Ewan and E.M. Purcell, "Observation of a line in the galactic radio spectrum," Nature 168 (4270): 356; September 1951.)

As soon as the maser was invented by Charles Townes in Columbia University, Professor Bloembergen realized its potential and with a group of outstanding students made further developments which won him the Nobel prize in 1964. It is hard to pinpoint the exact location so the work is recognized by a plaque beside his old office in the 2nd floor of Pierce hall: It was perhaps appropriate that this plaque was unveiled in the presence of Nico on his 90th birthday

“It was from this office that Nico Bloembergen generated the ideas for the 3 Level Maser and Non-Linear Optics and also supervised the experiments.”

Norman F. Ramsey was awarded the Nobel prize in Physics in 1989 "for the

invention of the separated oscillatory fields method and its use in the hydrogen maser and other atomic clocks", The invention was about 1947 and it is unclear whether it was at Columbia University (which he was leaving) or at Harvard University where he arrived. But further development in precision certainly deserves recognition by the following plaque on the ground floor of Lyman laboratory:

“In this room in 1959 D. Kleppner and N.F. Ramsey built the first atomic hydrogen maser, marking a dramatic improvement in the measurement accuracy.”

Professor Pound was still thinking fundamentally. At one corner of the central tower in Jefferson laboratory, on each of several floors, may be found the plaques:

“In 1959 R.V. Pound and G.A. Rebka, using the Mossbauer effect, measured the change in frequency of the 14 keV iron 57 line between the top and bottom of this tower, thereby measuring “the weight if photons” and confirming this aspect of the general theory if relativity.”

But important instrumentation advances in the less microscopic fields were also made in the ground floor of Cruft laboratory as the following plaque describes:

“In these rooms Ivan Sutherland built the first hardware matrix multiplier for a PDP1 computer. This enabled drawings in two dimensions to be seen in three dimensions and revolutionized the way architects and engineers do their work.”

The second Harvard cyclotron mentioned earlier was dismantled and the building removed in 2005. The most important work was probably the use of the proton beam for medical treatment as first envisaged by Robert Rathbun Wilson in 1947. (R.R.Wilson, "Radiological Use of Fast Protons," Radiology, 47:487-491; 1946.) The exact location of the cyclotron is partially the entrance to a parking garage but at the northern entrance of the NW building may be found the following recognition plaque:

“This is the site of the second Harvard cyclotron. It was designed in 1946, and first put into operation June 3rd, 1949. After more than twenty years of service in nuclear physics research, it provided a total of 9116 patients with medical treatment for cancer and tumors for another thirty years. The last treatment was on April 10 th, 2002. This pioneering program continued with a new cyclotron at Massachusetts General Hospital, and was copied by more than thirty accelerators throughout the world.”

But a more important discovery was made using the cyclotron laboratory facilities but not with the beam itself. This work was funded by a grant from Harvard University after a request to use funds from the joint ONR-AEC contract was denied. This is described by the following plaque:

“In 1967 using a radioactive source at this location in the basement of the cyclotron laboratory, A.M. Cormack, made the first CAT SCAN in history.” For this task, Cormack and Hounsfield shared the 1979 Nobel Prize in Medicine.

The general acclaim of these recognition plaques when installed has overcome previous reticence. There are obviously other places in Harvard where great physics done by great physicists deserves to be recognized, but are outside the jurisdiction of the physics department or the School of Engineering and Applied Sciences. The

Hemenway gymnasium the location of Dr. Hunt’s Underwater Sound Laboratory during WWII is one such. So also is the location underneath Sanders Theater where a physicist Dr Georg von Bekesy, although not a member of the physics department did his work which won him the 1961 Nobel prize in medicine.

There were also many theoretical studies of importance. But where was the theoretical work performed? At home? In the office? Or like famous discovery of “negative feedback” on a Hudson river ferryboat? Many experimental physics discoveries are made outside Harvard and a plaque does not seem to be sensible either. What about discoveries by Harvard Physics professors at Brookhaven National Laboratory, Fermilab, CERN or Grenoble? Or in astrophysics at a distant mountaintop examining an even more distant galaxy? Even the first to be recognized on this list, Wallace Sabine did his most well known work in downtown Boston by designing the acoustics in Symphony Hall.

Maybe it is best to leave ambiguity and flexibility for the future. A small plaque on the entrance to the 3rd floor bridge connecting the Laboratory for Integrated Science and Engineering (LISE) and the Gordon McKay Laboratory beyond it to the Cruft laboratory has the simpler sign:

“Bridge between Theory and Experiment”

It is left to the imagination, and perhaps to future generations, to decide on which side of the bridge lies the theory and on which lies the experiment.