Hubble's First Great Discovery

June 01, 1994

Modern astronomy and physics regularly confront the public with discoveries that exceed the wildest imaginings of science fiction writers. Ever since Einstein demonstrated the equivalence of matter and energy and the relative nature of space and time, astronomers have grappled with the mind-boggling implications of his theory, from the curvature of space to the existence of black holes.

The former was confirmed experimentally within a few years of publication of Einstein's General Theory of Relativity in 1915. But not until last week did researchers at the Space Telescope Institute in Baltimore announce they had found definitive proof of the existence of black holes -- exotic objects whose gravitational pull is so strong that not even light can escape their powerful embrace.

Since black holes are, by definition, invisible, astronomers can only infer their presence from the enormous gravitational force they exert on objects near them. That was the method used by the Hubble Space Telescope team to confirm the monster-size black hole at the center of a galaxy some 50 million light years away. Astronomers estimate the object contains 2 billion to 3 billion solar masses, or nearly as much matter as contained in the entire Milky Way galaxy of which our sun is part.

The confirmation of the first black hole surely rates as the Hubble Space Telescope's most important scientific discovery to date. Until a black hole was actually observed -- if only indirectly -- there always remained a possibility that either Einstein's theory was wrong or that some other phenomenon was at work. Now astronomers have much stronger grounds for believing there may be black holes lurking at the center of other galaxies in the universe as well, including our own Milky Way.

Still, the physical principles involved in black holes are so bizarre that just thinking about them requires a radical shift in our everyday concepts of reality. For example, the existence of black holes makes plausible the idea that there may exist regions of the universe where gravity is so powerful that space and time literally curve back on themselves, in effect forming a bridge to the past. Or that it might be possible to travel to distant parts of the universe by "tunneling" through "wormholes" in space. Until now, such notions have been the exclusive province of science fiction writers.

Hubble's discovery has just taken a giant step toward turning science fiction into science fact.

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