Barry Barish

Barry Clark Barish (born January 27, 1936) is an American experimental physicist. He is a Linde Professor of Physics, emeritus at California Institute of Technology. He is a leading expert on gravitational waves.

Birth and education

Barry C. Barish was born in Omaha, Nebraska, grew up in southern California, and attended high school in Los Angeles. He earned his B.A. in physics (1957) and his Ph.D. in experimental high energy physics (1962) at the University of California, Berkeley. He joined Caltech in 1963 as part of a new experimental effort in particle physics using frontier particle accelerators at the national laboratories.

Research

Among Prof. Barish's noteworthy experiments were those performed at Fermilab using high-energy neutrino collisions to reveal the quark substructure of the nucleon. These experiments were among the first to observe the weak neutral current, a linchpin of the electroweak unification theories of Glashow, Salam, and Weinberg.

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List of minor planets: 17001–18000

Gravitational wave

In physics, gravitational waves are ripples in the curvature of spacetime which propagate as waves, travelling outward from the source. Predicted in 1916 by Albert Einstein on the basis of his theory of general relativity, gravitational waves transport energy as gravitational radiation. The existence of gravitational waves is a possible consequence of the Lorentz invariance of general relativity since it brings the concept of a finite speed of propagation of the physical interactions with it. By contrast, gravitational waves cannot exist in the Newtonian theory of gravitation, which postulates that physical interactions propagate at infinite speed.

Before the direct detection of gravitational waves, there was indirect evidence for their existence. For example, measurements of the Hulse–Taylor binary system suggested that gravitational waves are more than a hypothetical concept. Potential sources of detectable gravitational waves include binary star systems composed of white dwarfs, neutron stars, and black holes. Various gravitational-wave observatories (detectors) are under construction or in operation, such as Advanced LIGO which began observations in September 2015.

Black hole

A black hole is a geometrically defined region of spacetime exhibiting such strong gravitational effects that nothing—including particles and electromagnetic radiation such as light—can escape from inside it. The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole. The boundary of the region from which no escape is possible is called the event horizon. Although crossing the event horizon has enormous effect on the fate of the object crossing it, it appears to have no locally detectable features. In many ways a black hole acts like an ideal black body, as it reflects no light. Moreover, quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation, with the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is on the order of billionths of a kelvin for black holes of stellar mass, making it essentially impossible to observe.

Objects whose gravitational fields are too strong for light to escape were first considered in the 18th century by John Michell and Pierre-Simon Laplace. The first modern solution of general relativity that would characterize a black hole was found by Karl Schwarzschild in 1916, although its interpretation as a region of space from which nothing can escape was first published by David Finkelstein in 1958. Black holes were long considered a mathematical curiosity; it was during the 1960s that theoretical work showed they were a generic prediction of general relativity. The discovery of neutron stars sparked interest in gravitationally collapsed compact objects as a possible astrophysical reality.