PAIR'S BINARY PULSAR DISCOVERY IN UMASS RESEARCH EARNS NOBEL

Author: By David L. Chandler, Globe Staff

Date: Thursday, October 14, 1993
Page: 1
Section: NATIONAL/FOREIGN

Joseph H. Taylor Jr. and Russell A. Hulse, now at Princeton University, made the discovery while both were at the University of Massachusetts at Amherst. Yesterday's announcement marks the first time work done by researchers at UMass has been so honored, a university spokesman said.

"There's been a lot of jubilation in the astronomy and physics departments today," said a UMass spokesman, who added that ceremonies to honor the laureates were expected soon.

The $825,000 prize was awarded for the first detection of a binary pulsar, a kind of aged, collapsed star emitting prodigious amounts of energy, orbiting another similar object.

The discovery by Taylor and Hulse launched a flurry of research in astrophysics that continues today and led to the most precise test yet of Albert Einstein's theory of relativity.

In the early 1970s, in their quest for the mysterious celestial beacons called pulsars, astrophysicist Taylor and his graduate student Hulse, along with other scientists at UMass-Amherst, used discarded telephone poles and wire mesh ordered from the Sears catalog to build a powerful radiotelescope next to the Quabbin Reservoir. The telescope's receiver, later attached to a telescope in Puerto Rico, was one of the inexpensive resources that helped make possible the discovery that earned the Nobel prize.

"We built the whole experiment there at UMass and then carried it down to Arecibo," a radiotelescope in Puerto Rico, Taylor said in a telephone interview yesterday. "We built it mostly out of used, surplus parts and whatever. It was pretty low budget."

At UMass, the Swedish Academy's announcement was met with pride. "We're pretty excited," said William Irvine, a UMass professor and director of the Five College Radio Astronomy Observatory. He said that at UMass, "we probably train more radio astronomers than anywhere else in the country." Radio astronomers use specialized telescopes to observe radio emissions from celestial objects.

Physicists and astronomers yesterday said the discovery was one that had long been considered of Nobel caliber.

"My wife asked me Monday who I thought would win, and Joe was at the top of my list," said astrophysicist John Bahcall, professor of natural science at Princeton University.

"Joe Taylor is the kind of person who makes you proud to be a human being," Bahcall continued. "He is such a modest, thoughtful, insightful, organized, hard-working and pleasant person."

Pulsars, for which British astronomer Antony Hewish received the Nobel Prize in 1974, were discovered in 1967. Many astronomers have since grumbled that graduate student Jocelyn Bell, who actually made the discovery under Hewish's direction, was unfairly bypassed for the honor. Some observers saw this year's recognition of Hulse for his contribution while doing his PhD thesis work -- he was the one who made the initial discovery of the binary pulsar -- as a counterpoint to the earlier omission.

At a press conference yesterday in Princeton, Hulse said he never forgot the moment the odd new pulsar showed up in the radio data. "It was a very exciting thing to have happened as a graduate student," said Hulse, 42, a research physicist at the Princeton Plasma Physics Lab. Taylor, 52, is now distinguished university professor of physics at Princeton.

Pulsars are dying stars, in which an amount of matter with a mass greater than the sun's has collapsed into a space just a few miles across. If it were possible to stand on the surface of a pulsar, its intense gravitational field would make a person weigh 100 billion times more than on Earth.

Pulsars spin very fast, and they emit twin beams of energy (in the form of radio waves) in opposite directions, like the beams from a lighthouse. Just as a lighthouse appears to a passing ship as a fixed point that emits regular flashes of light, pulsars appear to radiotelescopes on Earth as regular flashes of radio waves. The timing of the flashes, determined by the pulsar's rotation speed, makes them among the most accurate clocks in the universe.

But when Hulse and Taylor discovered a new pulsar in 1974, using the receiver built at UMass and attached to the world's largest radiotelescope, the Arecibo dish in Puerto Rico, they found something odd: The time between flashes changed, in a regular cycle, alternately speeding up and slowing down.

They realized that the only thing that could make such a perfect clock run fast and then slow was if it were in orbit around another massive object, presumably another pulsar whose beams were pointed the wrong way and were invisible from Earth.

Because the pulsar is moving around its orbit, sometimes it is moving toward Earth, causing its pulses to be bunched closer together and appear faster, and sometimes it is moving away, causing the pulses to spread out and appear slower, they concluded.

They realized that such a binary system would, according to the predictions of Einstein's theory, emit gravitational waves that would carry away some of its energy, causing it to slow down gradually. Taylor continued to observe the pulsar -- and two other similar ones he discovered later -- over the ensuing years, and eventually found that it was slowing down exactly as much as predicted by the theory.

"Here, a new, revolutionary 'space laboratory' has been obtained for testing Einstein's general theory of relativity," the Swedish Academy wrote in its citation. "So far, Einstein's theory has passed with flying colors."

Gravitational waves have never been detected, despite several efforts to do so. In the meantime, Taylor and Hulse's findings are the strongest evidence for their existence. Bahcall, the Princeton astrophysicist, said, "I don't think you'd find any physicist who wouldn't say it's a very precise confirmation of general relativity."

The binary pulsar discovery also provided the first way to determine the exact mass of a pulsar, because theory says the speed of objects orbiting each other is precisely determined by their mass. This enabled astronomers to establish the size of the pulsar to within a margin of error of about 10 percent.

And the technology used to build the radiotelescope and detection equipment used for the discovery have led to practical spinoffs. Richard Huguenin, who was director of the Five College observatory when Taylor and Hulse did their work there, left in 1982 to set up a Massachusetts company called Millitech, which makes products derived from radiotelescope technology. The company plans to make a collision-avoidance radar system for cars and remote-sensing equipment for environmental monitoring.

Taylor, when asked how the prize would affect him, said: "I hope not very much. I'm very happy doing what I do, and I'm not looking for an abrupt change. I hope my life won't get so complicated that I won't be able to continue meeting with students every day."