Chuck Bednar for redOrbit.com – @BednarChuck
This year marks the 100th anniversary of Einstein’s general theory of relativity, and one century after its publication, modern technology has finally advanced to the point where the concept can be put to the test to see if it can survive the most extreme conditions.
According to Space.com, Einstein originally determined that the laws of physics were the same for all non-accelerating observers, and that the speed of light in a vacuum was independent of the motion of those observers. This theory of special relativity introduced new concepts of space and time and established a new framework for the field of physics.
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However, the German-born scientist then spent the next 10 years attempting to add acceleration to the theory. He published his theory of general relativity, and in it he determined that massive objects cause a distortion in space and time (or space-time) that can be felt as gravity, the website added. Einstein then developed a series of equations that related the curvature of space-time to the momentum and the energy of the matter and radiation that exists in a particular area.
Will the theory withstand?
Over the course of the next century, the theory was able to withstand every challenge scientists could throw at it, according to Live Science, and remains one of the pillars of physics today. Yet it has only recently been able to conduct experiments under the most extreme conditions to see if the theory hold true, or if it begins to break down. Now, scientists have the technological ability to search for physics that exist outside the scope of general relativity, the website added.
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“To me, it is absolutely amazing how well general relativity has done after 100 years. What he wrote down is the same thing we use today,” said University of Florida theoretical physicist Clifford Will. However, even though previously there has been no evidence to suggest that there is anything wrong with the theory, he emphasized that it is “important to test the theory in regimes where it hasn’t been tested before.”
Einstein’s theory, which correctly predicted the existence of black holes and is used as the basis of the currently accepted notion that the universe is expanding and accelerating, has already been confirmed through multiple observations. In fact, it was used by the scientist himself to predict the orbital motion of Mercury, and also predicted the phenomenon called gravitational lensing, in which an object is space was large enough to actually bend light itself.
Extreme testing
Nonetheless, as Live Science and Mashable have reported, general relativity has not yet been tested in extremely strong gravitational fields. In order to find potential candidates for testing the theory in the manner, scientists are looking for gravitational waves, or ripples in space-time that are produced by violent cosmological events, such as the merging of two massive bodies.
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While gravitational waves are short-lived and incredibly difficult to detect, there are experiments currently ongoing that are capable of detecting these space-time ripples, and Will explained that there is a “very good chance” that they will be directly detected “in the next couple of years.”
One such experiment is known as the Laser Interferometer Gravitational-Wave Observatory (LIGO). LIGO uses lasers capable of detecting miniscule distortions in two long, L-shaped detectors, Live Science said. As ripples in space-time pass through those detectors, they stretch and compress space, which can change the length of the detector in such a way that the observatory can measure the waves.
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LIGO ran from 2002 through 2010, and was unable to detect any gravitational waves during that time. It went offline for upgrades in 2010, and a successor called Advanced LIGO is scheduled to begin operations later this year. But it is not the only experiment designed to test general relativity: some scientists hope to test it by polarizing gravitational waves in order to compare the actual properties they observed to those predicted by Einstein’s theory.
“Anything that deviates from [these predictions] would be bad for the theory,” Will said. However, he predicts that if researchers are able to detect gravitational waves, their work will only serve to strengthen what we already believe about the concepts of physics. “My opinion is, we’re going to keep proving general relativity to be right,” he noted.
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