Two Johns Hopkins scientists played a role in the conception of an instrument that is now being tested in the space shuttle as part of a long-range mission to search for stars and galaxies made of antimatter.

The space shuttle Discovery blasted off June 2, beginning a 10-day mission to test the Alpha Magnetic Spectrometer, which will use a super-strong magnet to look for the telltale trajectory of atoms that come from antimatter. Scientists plan to install the instrument in the international space station early in the next century.

"We are getting our space legs under us," said Aihud Pevsner, a high-energy particle physicist in the Department of Physics and Astronomy.

Pevsner and research scientist Andre Gougas were among physicists who, in a published scientific paper, officially proposed the idea in 1994. The project, led by Nobel Prize-winning physicist Samuel Ting, from the Massachusetts Institute of Technology, involves scientists from 37 universities and laboratories around the world.

The existence of antimatter lies at the heart of modern physics. It is the essential glue needed to merge two major schools of thought explaining atomic structure and function: quantum mechanics, which reveals that subatomic particles behave as both particles and waves, and Einstein's theory of relativity. Both views are needed to explain the behavior of atoms, but they are incompatible without antimatter.

Antimatter also is a key piece of the puzzle of how the universe was born. All versions of the Big Bang theory require that, at some point after the initial explosive birth, there had to be equal parts of matter and antimatter.

Once considered strictly theoretical, antimatter has been steadily emerging into the world of reality. Since 1932, when a Caltech physicist discovered the antimatter equivalent of an electron--a positron--scientists have found "antiparticles" for just about every subatomic particle in existence.

Antiparticles look and behave the same as ordinary subatomic particles. But although they have the same mass as their matter counterparts, they have the opposite electrical charge. If particles and antiparticles meet, they instantly annihilate each other, releasing a large amount of energy in the process.