The Hindu : Front Page : Space probes to put Einstein to the test

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Friday, Jun 29, 2007
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Space probes to put Einstein to the test

Alok Jha

When it comes to mysteries, they don’t get any bigger than this: how did the universe begin, and why did it turn out the way we see it today? A century ago, the questions inspired Albert Einstein to develop the radical ideas that made him famous. Now, the United States National Aeronautics and Space Administration (NASA) plans to build on those ideas with a series of missions that will study the most exotic phenomena in the universe.

The Einstein Probes Office (EPO), set up on Wednesday by the agency, will coordinate five missions to study dark energy and black holes and hunt for clues to the origin and evolution of the universe — areas of physics where Einstein’s general theory of relativity has been hugely important.

The plan includes two big space-based observatories and a series of smaller probes to exhaustively test Einstein’s ideas.

The main observatory, the Laser Interferometer Space Antenna, will look for the elusive gravitational waves predicted by general relativity when it launches in 2015. Martin Barstow, head of the physics and astronomy department at Leicester University, U.K., described the waves as “an oscillation in space-time, in just the same way that light is an oscillation in electromagnetic space and sound is an oscillation in gas.”

He added: “Until you really detect them, you don’t know if the theory is correct. Once you do detect them, you can use them in the same way you use light to probe processes in the universe, like creation of black holes or merging of two stars.”

The second large observatory, Constellation-X, will launch in 2016 and watch black holes as matter falls into them. Einstein made specific predictions about the behaviour of matter near a black hole and, because it will be so sensitive, Constellation-X will expose any flaws in the physicist’s calculations.

Of the other missions, the most developed is a plan for a probe to study dark energy. Though it makes up more than 70 per cent of the universe, no one knows what dark energy really is.

The Joint Dark Energy Mission will study the violent star explosions called supernovas in distant galaxies in an attempt to work out how quickly they are moving away from us. Watching supernovas was how dark energy was first discovered in 1998.

Other proposals

The other two proposals for the EPO are a mission to find and take detailed pictures of new black holes and one to study a crucial early time in the formation of the universe called inflation. Scientists think that around 30 seconds after the big bang, some 14 billion years ago, the universe went through a split-second of rapid expansion which enabled stars to form and life to exist.

NASA has short-listed three candidates for its dark energy probe. The rest are still at early stages of development. —

Guardian Newspapers Limited 2007

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