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From the August 2009 Scientific American Magazine | 68 comments

Surprises from General Relativity: "Swimming" in Spacetime ( Preview )

The possibility of "swimming" and "gliding" in curved, empty space shows that even after nine decades, Einstein's theory of general relativity continues to amaze

By Eduardo Guéron   

 


Miracle Studios (www.miraclestudios.com)

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Key Concepts

  • In Albert Einstein’s theory of general relativity, gravity arises from spacetime being curved. Today, 90 years after Einstein developed the theory’s equations, physicists are still uncovering new surprises in them.
  • For example, in a curved space, a body can seemingly defy basic physics and “swim” through a vacuum without needing to push on anything or be pushed by anything.
  • Curved spacetime also allows a kind of gliding, in which a body can slow its fall even in a vacuum.

More from the Magazine

In a famous series of stories in the 1940s, physicist George Gamow related the adventures of one Mr. C.G.H. Tompkins, a humble bank clerk who had vivid dreams of worlds where strange physical phenomena intruded into everyday life. In one of these worlds, for instance, the speed of light was 15 kilometers per hour, putting the weird effects of Einstein's theory of special relativity on display if you so much as rode a bicycle.

Not long ago I figuratively encountered one of Mr. Tompkins's great grandsons, Mr. E. M. Everard, a philosopher and engineer who is carrying on his ancestor's tradition. He told me of an amazing experience he had involving some recently discovered aspects of Einstein's theory of general relativity, which I will share with you. His remarkable story is replete with curved space­time, cats twisting in midair, an imperiled astronaut dog paddling through a vacuum to safety—and Isaac Newton perhaps spinning in his grave.

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