May possibly 4, 2011: Einstein was correct again. There is a space-time vortex around Earth, and its shape specifically matches the predictions of Einstein's principle of gravity.
Scientists confirmed these details at a press conference today at NASA headquarters the place they introduced the lengthy-awaited benefits of Gravity Probe B (GP-B).
"The space-time around Earth seems to be distorted just as basic relativity predicts," claims Stanford College physicist Francis Everitt, principal investigator of the Gravity Probe B mission.
An artist's notion of GP-B measuring the curved spacetime around Earth. [more]
"This is an epic outcome," provides Clifford Will of Washington College in St. Louis. An expert in Einstein's theories, Will chairs an independent panel of the National Research Council set up by NASA in 1998 to check and review the final results of Gravity Probe B. "One day," he predicts, "this will be penned up in textbooks as one of the traditional experiments in the history of physics."
Time and space, in accordance to Einstein's theories of relativity, are woven collectively, forming a four-dimensional fabric called "space-time." The mass of Earth dimples this material, a lot like a large individual sitting in the center of a trampoline. Gravity, says Einstein, is basically the motion of objects following the curvaceous lines of the dimple.
If Earth ended up stationary, that would be the end of the story. But Earth is not stationary. Our world spins, and the spin must twist the dimple, a bit, pulling it around into a 4-dimensional swirl. This is what GP-B went to space in 2004 to check.
The idea behind the experiment is straightforward:
Put a spinning gyroscope into orbit close to the Earth, with the spin axis pointed toward some distant star as a fixed reference point. Totally free from external forces, the gyroscope's axis really should continue pointing at the star--permanently. But if space is twisted, the course of the gyroscope's axis ought to drift over time. By noting this adjust in path relative to the star, the twists of space-time could be measured.
In practice, the experiment is immensely difficult.
One of the super-spherical gyroscopes of Gravity Probe B. [a lot more]
The four gyroscopes in GP-B are the most perfect spheres ever made by individuals. These ping pong-sized balls of fused quartz and silicon are 1.5 inches across and in no way differ from a best sphere by far more than forty atomic layers. If the gyroscopes weren't so spherical, their spin axes would wobble even without the outcomes of relativity.
In accordance to calculations, the twisted space-time all around Earth must result in the axes of the gyros to drift basically .041 arcseconds over a year. An arcsecond is 1/3600th of a diploma. To evaluate this angle fairly well, GP-B essential a wonderful precision of .0005 arcseconds. It's like measuring the thickness of a sheet of paper held edge-on 100 miles away.
"GP-B researchers had to invent complete new systems to make this possible," notes Will.
They designed a "drag free" satellite that could brush versus the outer layers of Earth's ambiance without disturbing the gyros ( via science.nasa.gov ).