© American Institute of Physics, Emilio Segré Visual Archives, W.F. Meggers Collection.
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© American Institute of Physics, Emilio Segré Visual Archives, W.F. Meggers Collection. |
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A history of proofs Amazingly enough, as the century closes scientists are still gathering evidence that the revolutionary physicist Albert Einstein got it right when he developed relativity theory early in this century. | ||
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The first evidence came almost immediately after Einstein published his theory of gravity -- called "general relativity" -- in 1916. The theory explained a deviation in the timing of Mercury's orbit which had violated Newton's laws of gravitation. | |
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In 1979, astronomers detected a gravitational lens -- light from distant galaxies that had been focused by the gravity of galaxies closer to us. We'll cover that shortly. | |
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In 1995, scientists created a bizarre form of matter at temperatures barely above absolute zero -- fulfilling another Einsteinian prediction. We'll get to that weird stuff later on. | |
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And on Nov. 6, two groups of scientists found that spinning objects seem to "drag" space-time around with them. They didn't measure roulette wheels, but rather emissions from near black holes and neutron stars -- two of the weirdest and most massive objects around. Although too new to be considered proof that space-time can be dragged by massive spinning objects, as Einstein's theories predict, it's highly suggestive evidence. | |
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What's a black hole? What is space-time? Why should I care?
Face it.
To a great extent, Einstein's revolution in physics grew from his philosophy of nature and insistence that physical laws must be true everywhere, not just here on Earth, but also in fast-moving space ships and inside stars. He combined that with a phenomenal intuition for how nature would work. "Einstein ... relied on his own innate intuition as to how things ought to behave," wrote Kip Thorne, a California Institute of Technology physicist.
Thorne (in "Black Holes and Time Warps" in the bibliography) says Einstein was also exceptional for working in isolation. "He paid little attention to others' work. He seems not to have read any of the important technical articles" on space and time. And yet Einstein concocted theories whose predictions are still being vindicated almost a century later.
All those attributes -- philosophy, intuition and isolation -- were reflected in Einstein's audacious effort to rewrite Newton's laws of gravitation and motion. For a starting point, Einstein maintained that the speed of light must be constant throughout the universe. He then proposed that gravity would affect light and space-time -- the fabric of the universe that humans don't see, but which physicists recognize as the backdrop for all events, atomic, human, cosmic and comic.
And it was that stuff -- space-time -- that was the subject of the most recent proof of Einstein's theories. In November, two groups of scientists said they'd found a distortion of space-time around neutron stars and black holes.
Time for our no-fuss, five-minute guide to black holes. | ||
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8 documents. Bibliography | Credits | Search |
Like you, The Why Files has a hard time fathoming the subtle, abstract notions of relativity, but rest assured that we checked our facts with people who actually understand it.