The diversity of scientific opportunities that now exists at Columbia has grown out of a long and distinguished tradition of physics teaching and research. Columbia graduates, along with many other scientists who spent their formative years here, have gone on to make extraordinary contributions to science as researchers, teachers, and intellectual leaders. The array of Nobel prizes acknowledges singular accomplishments that are widely recognized by their colleagues and the lay community. Such awards typically represent only the most visible points in a research program. A Nobel prize list only hints at the wide diversity of accomplishment underpinning forefront physics research done by Columbia students and faculty over the decades. Large numbers of Columbia graduates, along with many other scientists who spent their formative years here, have gone on to make extraordinary contributions to science in research, as teachers, and as intellectual leaders.
A CENTURY AGO
The graduate department was formally established in 1892, although the roots of graduate physics can be traced to the opening of the School of Mines in 1864. The first physics PhD, Robert Millikan, went on to win a Nobel Prize. The central figure in the early years of the Department was Michael Pupin, who contributed substantially to new discoveries involving X-rays and to the continued understanding and applications of electromagnetism. He served as Department Chair for many years. Under his impressive leadership, the present Pupin Laboratory was completed in 1925 to serve as the home of the Physics Department. After his death in 1935, the building was named for him.The Department still resides here.
In May 1899, the American Physical Society was founded at Columbia. The Earnest Kempton Adams (EKA) Fund was established in 1904, enabling the department of Physics to invite distinguished scientists to Morningside. H.A. Lorentz was appointed EKA Lecturer in 1905-1906 and Max Planck in 1909. One of Lorentz’ most important works, The Theory of Electrons, was written during his tenure at Columbia.
In the early years of the twentieth century, Lorentz’ work had led toEinstein's theory of relativity, and Planck's black-body radiation formula led Einstein to the concept of the quantum, which culminated in the theory of quantum mechanics, developed by Bohr, Schroedinger, Heisenberg and many others in Europe over the two decades from 1910-1930. These ideas underlie our present understanding of nature at its most fundamental level, and represent great historical intellectual achievements. Most modern scientific and technological developments--nuclear energy, atomic physics, molecular beams, lasers, x-ray technology, semiconductors, superconductors, supercomputers-- were realized only because we could build on the foundations of relativity and quantum mechanics. The Columbia Physics Department played significant roles in several of these and related developments over ensuing decades.
I.I. Rabi, a Columbia graduate student in the 1920’s, was very interested in the new Quantum Mechanics being developed primarily in Europe. After completing his degree, he received a fellowship to spend a few years in European laboratories. On his return to Columbia, he spearheaded successful efforts to put Columbia, and the U.S., at the forefront of scientific research.
By 1931, Columbia had become a visible science presence with Harold Urey’s discovery of deuterium (Nobel Laureate in Chemistry, 1936) using a new spectrometer in Pupin Laboratory. That reputation continued as Rabi did his famous work with atomic beams and George Pegram investigated phenomena associated with the newly discovered neutron. In the fall of 1938, Italian fascism had created a hostile environment for Enrico Fermi, so he decided to leave his native country. His Nobel Prize award that year gave him the perfect opportunity to visit elsewhere. He wrote to George Pegram regarding this possibility, and received every encouragement to come to Columbia.
The war years saw great activity at Columbia and by Columbia faculty.Soon after Fermi arrived, he set about verifying the fission properties of the Uranium isotopes and pursuing what later became the Manhattan Project to develop the first nuclear weapon. Rabi, as wartime Director of Research of the Radiation laboratory located at MIT, worked on the development of radar.
MID 20th CENTURY - ATOMIC AND NUCLEAR PHYSICS
I.I. Rabi's contributions to the development of atomic and molecular physics and some of the basic discoveries in nuclear fission by Enrico Fermi and his collaborators ushered in a golden era of fundamental research. This period just prior to World War II was marked particularly by Rabi’s measurements of the spins and magnetic moments of atoms and nuclei, by the construction of the “Pupin cyclotron” by Dunning, and by the work of Fermi, Dunning and others on nuclear fission. After the war, many experiments were groundbreaking, particularly those by Polykarp Kusch and Henry Foley on the magnetic moment of the electron and Willis Lamb's work on the fine structure of hydrogen. These were crucial to the development of quantum electrodynamics. Theoretical research in the 1940s involved close collaboration with the atomic physics experiments. Goals emphasized calculations to clarify precise predictions of quantum electrodynamics to compare with experiment.
Microwave techniques developed by Columbia faculty members during the war were later used to explore molecular spectra; the observation of large nuclear quadrupole moments stimulated the unified nuclear model of James Rainwater and Aage Bohr. Molecular spectroscopy also led Charles Townes and his collaborators to the development of the maser, the microwave precursor of the laser. These works were recognized by the Nobel Foundation.
High energy physics and properties of subatomic particles increasingly became a major postwar focus. In 1950, Columbia's cyclotron was commissioned at Nevis Laboratories in Westchester County about twenty miles north of Morningside. The Nevis Laboratories continue to house substantial infrastructure in support of experimental programs in the department.T. D. Lee, his collaborators, and their students made major strides in understanding the symmetries of subatomic particles, culminating in the prediction of parity violation in the weak interactions. The effect of maximal parity nonconservation was quickly observed in the landmark nuclear physics experiment conducted in Pupin by C.S. Wu.Soon afterwards, maximal parity violation was also found in pion- and muon- decay experiments by Leon Lederman and Richard Garwin at Nevis.
HIGH ENERGY AND NUCLEAR PHYSICS
The desire to investigate matter on an increasingly fine scale led to experiments using beams of increasingly high energies. Beginning in the 1950’s, the Nevis cyclotron and accelerators at Brookhaven National Laboratory were used in a number of experiments that continued beyond the decade. The structure of nuclei was delineated by observing X-ray transitions in muonic atoms; observations of pion and muon decay constituted further validation of maximal parity nonconservation; and in 1964, Lederman, Mel Schwartz, and Jack Steinberger proved that the muon neutrino was distinct from the electron neutrino.
By the early 1970s, particle physicists began using even higher energy accelerator beams, and Columbia experimenters spread out to accelerators in Europe and the new Fermi National Accelerator Laboratory (FNAL) west of Chicago. By mid-decade, the Standard Model of elementary particles was becoming established, with electroweak interactions and quantum chromodynamics (QCD) describing the basic forces and constituents of matter. It ultimately incorporated three families of leptons (electron-like) and three families of quarks (proton-like) as the observed constituents, with two members in each family. The second quark family, with one already well-established (“strange”) member was then confirmed to have a second member: the “charm” quark.In 1977, Lederman led an effort at FNAL which discovered the first member (“bottom” quark) of the third quark family. (The remaining very massive “top quark” was confirmed in 1995 by experiments performed at Fermilab; collaborators from Columbia participated in this discovery.)
During the ensuing two decades, experiments at FNAL with neutrino beams, led by Columbia experimenters, verified electroweak predictions of the Standard Model, and definitively established the quark and gluon constituency of nucleons assumed in QCD. Furthermore, these and other experiments demonstrated QCD as the best predictor of measurable strong interaction phenomena. Beginning in 1985, Columbia physicists led experiments using the accelerator complex at the German DESY laboratory, where predictions of the Standard Model were further verified while searching for specific effects beyond the Model. Properties of nucleon structure and QCD, the force holding quarks within the proton were investigated in many different ways and in phenomena that QCD did not easily predict. In the process, the proton was found to contain huge numbers of gluons carrying very tiny fractions of the proton momentum as expected in the developed QCD theory; where such gluons carry the strong interaction force.
Many studies of the second quark family’s charm quark were carried out in the period between 1985 and 1995 by Columbia physicists at the Cornell accelerator. These measured specific properties of charm, and properties of the binding of charmed quarks inside nucleons. Additional studies of important properties of the bottom quark were led by Columbia physicists using the Stanford SLC accelerator during the same period. This program also provided important information on the properties of the elementary bosons that carry the electroweak forces.
Substantial theoretical work on QCD continues to be carried out by Columbia theorists, with many difficulties to be overcome in making predictions from such a highly nonlinear theory. Since 1981, Columbia theoreticians have led in designing, constructing, and utilizing novel parallel processing computing systems to carry out these calculations. The details of many strong interaction phenomena, including the binding properties and masses of specific meson and baryon states, could begin to be predicted with accuracy.
By 1990, Columbia-led experiments were exploring implications of QCD in collisions of heavy nuclei at higher and higher energies. In collaboration with Brookhaven National Laboratory, the Relativistic Heavy Ion Collider (RHIC), constructed to accelerate and collide heavy nuclei, is advancing our understanding of nuclei and explores new forms of nuclear matter, including the quark-gluon plasma. This program continues today.
Columbia scientists will be playing an important role in major experiments at the soon-to-be completed LHC super-high energy collider in Switzerland. Among other exciting possibilities, these may at last reveal the origin of the masses of the familiar elementary particles of our Universe. Columbia physicists are also continuing to play important leadership roles using neutrinos to understand their intrinsic nature, including their masses and interactions with each other.
Astrophysics had its roots in early collaborations between astronomers and physicists at Columbia. In 1967 the Columbia Astrophysics Laboratory (CAL) was founded and, under the leadership of Columbia physicist Robert Novick, this fledgling organizationquickly moved to the frontier of high energy astrophysics. By the early 1970's, CAL was, along with MIT, Harvard, and the NASA Goddard Space Flight Center, the architect of a series of three satellites that would make X-ray observations a central feature of our study of the Universe. Today the astrophysics lab boasts 23 faculty, 37 other PhD scientists and 40 graduate students from three departments.
In addition to studies of extraterrestrial X-rays, areas of research in the department have included measurements of the very highest energy cosmic rays; design, construction, and operation of innovative instruments to find the thus far undiscovered dark matter; measurement of the radiation from the Big Bang, detection and studies of neutron stars and black holes; and charting the star formation history of the Universe. Throughout the entire period, such experimental and observational efforts have always complementedforefront theoretical and phenomenological research.
ATOMIC AND CONDENSED MATTER PHYSICS
Columbia had, from the postwar period onwards, been involved in the study of complex material and electromagnetic systems, both from theoretical and experimental perspectives. The Columbia Radiation Lab gave such programs a home and work on laser phenomena has continued in the Department since the invention of the maser here by Townes and Schwalow. Experimental condensed matter physics had a rebirth in the department in the late 1980’s with the establishment ofprograms studying spin glasses and high temperature superconducting systems with muons and neutrons. The program grew with new people and efforts, both from joint programs with other departments and with new individuals who joined the department. One new appointment, Horst Stormer, received the Nobel Prize soon after coming to Columbia for his discovery of the fractional quantum hall effect. More recently, interdisciplinary collaboration between physics, chemistry and the engineering school has given Columbia a leadership role in the burgeoning field of nanoscience.
Although some of today’s questions and the tools used to answer them were inconceivable 50 years ago, one aspect of life in Pupin has not changed: Science at Columbia continues to be done by people who care deeply and passionately for the truth.
More detailed descriptions of current experimental and theoretical efforts can be found at the department’s research web page.