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Thu 23rd of November 2017


IAS EXPRESS - Free Download

2017 Nobel Prize in Physics Awarded to LIGO Black Hole Researchers

Dr. Weiss, 85, Dr. Thorne, 77, and Dr. Barish, 81, were the architects and leaders of LIGO, the Laser Interferometer Gravitational-wave Observatory, the instrument that detected the gravitational waves, and of a sister organization, the LIGO Scientific Collaboration, of more than a thousand scientists who analyzed the data.

Einstein’s General Theory of Relativity, pronounced in 1916, suggested that matter and energy would warp the geometry of space-time the way a heavy sleeper sags a mattress, producing the effect we call gravity. His equations described a universe in which space and time were dynamic. Space-time could stretch and expand, tear and collapse into black holes — objects so dense that not even light could escape them. The equations predicted, somewhat to his displeasure, that the universe was expanding from what we now call the Big Bang, and it also predicted that the motions of massive objects like black holes or other dense remnants of dead stars would ripple space-time with gravitational waves.

These waves would stretch and compress space in orthogonal directions as they went by, the same way that sound waves compress air. They had never been directly seen when Dr. Weiss and, independently, Ron Drever, then at the University of Glasgow, following work by others, suggested detecting the waves by using lasers to monitor the distance between a pair of mirrors. In 1975, Dr. Weiss and Dr. Thorne, then a well-known gravitational theorist, stayed up all night in a hotel room brainstorming gravitational wave experiments during a meeting in Washington.

Dr. Thorne went home and hired Dr. Drever to help develop and build a laser-based gravitational-wave detector at Caltech. Meanwhile, Dr. Weiss was doing the same thing at M.I.T.

The technological odds were against both of them. The researchers calculated that a typical gravitational wave from out in space would change the distance between the mirrors by an almost imperceptible amount: one part in a billion trillion, less than the diameter of a proton. Dr. Weiss recalled that when he explained the experiment to his potential funders at the National Science Foundation, “everybody thought we were out of our minds.”

The foundation, which would wind up spending $1 billion over the next 40 years on the project, ordered the two groups to merge, with a troika of two experimentalists, Drs. Weiss and Drever, and one theorist Dr. Thorne, running things. The plan that emerged was to build a pair of L-shaped antennas, one in Hanford, Wash., and the other in Livingston, La., with laser light bouncing along 2.5-mile-long arms in the world’s biggest vacuum tunnels to monitor the shape of space.

In 1987, the original three-headed leadership of Drs. Weiss, Drever and Thorne was abandoned for a single director, Rochus Vogt of Caltech. Dr. Drever was subsequently forced out of the detector project. But LIGO still foundered until Dr. Barish, a Caltech professor with a superb pedigree in managing Big Science projects, joined in 1994 and then became director. He reorganized the project so that it would be built in successively more sensitive phases, and he created a worldwide LIGO Scientific Collaboration of astronomers and physicists to study and analyze the data. “The trickiest part is that we had no idea how to do what we do today,” he commented in an interview, giving special credit to the development of an active system to isolate the laser beams and mirrors from seismic and other outside disturbances.

“Without him there would have been no discovery,” said Sheldon Glashow, a Nobel Prize-winning theorist now at Boston University.

The most advanced version of LIGO had just started up in September 2015 when the vibrations from a pair of colliding black holes slammed the detectors in Louisiana and Washington with a rising tone, or “chirp,” for a fifth of a second.

It was also the opening bell for a whole new brand of astronomy. Since then LIGO (recently in conjunction with a new European detector, Virgo) has detected at least four more black hole collisions, opening a window on a new, unsuspected class of black holes, and rumors persist of even more exciting events in the sky.


Prelims Question of the Day

With reference to 'Natural Rate of Unemployment', consider the following statements.

1. It is the level of unemployment in an economy that is just consistent with a stable rate of Inflation.

2. It is the unemployment that prevails when all markets in the economy are in equilibrium.


(a)1 and 2

(b)2 only

(c)1 only

(d)None of the above

Mains Question of the Day

1.GS-No party in power can afford to ignore Directive Principles of State Policy. Comment.(200 Words)

2.Political Science - Explain the role of non state actors, like IMF, World Bank, European Union and MNCs, in modulating and transforming the broad dynamics of international relations. (250 Words).

3.SOCIOLOGY - What is the impact of Globalization on the structure and mobilization of the working class in India? (250 Words).

Sociology - Thinkers