- U.S. NEWS
- Updated April 25, 2013, 7:28 p.m. ET
Theory of Einstein's Proved Right—Again
Scientists have
subjected Albert Einstein's famous theory of gravity to its toughest
real-world test so far—and it has prevailed.
The theory, which was published nearly
a century ago, had already passed every test it was subjected to. But
scientists have been trying to pin down precisely at what point
Einstein's theory breaks down, and where an alternative explanation
would have to be devised.
Einstein's framework for his theory of
gravity, for example, is incompatible with quantum theory, which
explains how nature works at an atomic and subatomic level.
Consider that for a black hole,
Einstein's theory "predicts infinitely strong gravitational fields and
density. That's nonsensical," said Paulo Freire, an astrophysicist at
the Max Planck Institute for Radioastronomy in Germany and co-author of
the study, which appears in the journal Science.
And so scientists are testing the
general theory not because they think it is wrong but because they are
certain it can't be the final explanation—just as Isaac Newton's notion
of gravitational force was superseded by Einstein's.
Einstein's general theory of
relativity states that objects with mass cause a curvature in
space-time, which we perceive as gravity. Space-time, according to
Einstein's theories of relativity, is a four-dimensional fabric woven
together by space and time.
For example, a bowling ball causes a
dent in a mattress, and that dent changes the otherwise straight motion
of a nearby marble on the same mattress. Similarly, the mass of the sun
distorts the space-time around it. A body with less mass, like the
earth, travels along one path in that distorted space, which we call its
orbit.
Dr. Freire and his colleagues put
Einstein to the test in a cosmic laboratory 7,000 light years from
earth, where two exotic stars are circling each other. One, known as a
white dwarf, is the cooling remnant of a much lighter star. Its
companion is a pulsar, which spins 25 times every second. Though the
pulsar is just 12 miles across, it weighs twice as much as the sun.
AFP/Getty Images
Physicist Albert Einstein.
More WSJ Science Coverage
"When you have
such a big mass in such a small space you have extremely high gravity,"
said Charles Wang, a theoretical physicist at the University of
Aberdeen, Scotland, who wasn't involved in the study.
The gravity on the pulsar's surface is
300 billion times as great as the gravity on Earth. The conditions there
approach the relentless, overwhelming power of a black hole, which
swallows even light.
"We're testing Einstein's theory in a region where it has never been tested before," said Dr. Freire.
The pulsar and white dwarf pair emit
gravitational waves and the binary star system gradually loses energy.
As a result, the stars will move closer to each other and orbit faster.
Einstein's theory suggests the stars' orbital periods—the time they take
to go around each other—ought to shrink by about eight-millionths of a
second per year.
Dr. Freire's and his colleagues used
several telescopes to take precise measurements of the two-star system.
Their results perfectly matched the Einstein-based prediction.
Though Einstein's framework remains
intact so far, "the study is significant for the way observations by
astronomers are helping to identify new, extreme cases" to test his
general theory of gravity, said Dr. Wang.
Einstein's theory was first—and
dramatically—confirmed during a solar eclipse within four years of its
publication, making him an instant celebrity. When asked how he would
have felt if he had been proven wrong, Einstein replied: "I would have
felt sorry for the Lord. The theory is correct."
Write to Gautam Naik at
gautam.naik@wsj.com
end quote :
I'm wondering after reading this whether a space time continuum can
actually exist outside of a Black hole gravitational field which holds
our galaxy and every other galaxy together and keeps it from spinning
off in all directions?
No comments:
Post a Comment