from NRAO
Let’s face it – gravity is weird. Sure, we have enough everyday experience with Earth’s little gravitational field that most of us have figured how to function within it. But at the extremes of existence – at the scale of the very small, or the extremely dense – its actions aren’t predicted by the centuries-old Newtonian construct.
Along comes Einstein . . .
Pulsars are extremely dense remnants of collapsed massive stars, spinning around hundreds of times each second. Their intense magnetic field enables beacons of radio-frequency waves to sweep through the sky at regular, predictable intervals – a discovery made by Jocelyn Bell Burnell in 1967, thanks to an experiment designed by her graduate advisor.*
These extremely dense objects – each so dense that it would be like squishing the mass of our Sun into a region the size of Kansas City – are so dense that when they’re close to each other, they affect each other and move in ways not predicted by Newtonian gravitational theory. The mathematics of Einstein’s theory of General Relativity predicts that one pulsar’s gravitational pull, along with its spinning, should produce a “tug” on the other pulsar that could be measured by how the second pulsar’s spin changes.
Astronomers have measured this “tug” and found that it aligns perfectly with that predicted by GR.
In the binary-pulsar study, General Relativity “passed the test” provided by such an extreme environment, the scientists said.
“It’s not quite right to say that we have now ‘proven’ General Relativity,” Breton said. “However, so far, Einstein’s theory has passed all the tests that have been conducted, including ours.”
The strength of any scientific theory lies in its ability to generate testable hypotheses. Intelligent design doesn’t have that ability; instead, its proponents try to tear down evolutionary theory to suit their own religious agenda. ID proponents also try to paint science as dogmatic and unquestioning . . . apparently they don’t have a clue as to how REAL science is done in the real world.
Congrats to the McGill group for several years of painstaking work.
Thanks to P.S. for the tip.
*ETA: To learn more about Jocelyn Bell Burnell’s life and work and that of other outstanding scientists, check out Nobel Prize Women in Science: Their Lives, Struggles and Momentous Discoveries. It’s a must-read!
Posted by Cheryl Shepherd-Adams
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on Monday, July 7th, 2008 at 9:14 am.
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