NASA successfully launched the Gravity Probe B satellite yesterday after a software problem forced a delay on Monday. The Gravity Probe B is designed to test two heretofore unproven parts of Einstein’s general theory of relativity:
The experiment will check, very precisely, tiny changes in the direction of spin of four gyroscopes contained in an Earth satellite orbiting at 400-mile altitude directly over the poles. So free are the gyroscopes from disturbance that they will provide an almost perfect space-time reference system. They will measure how space and time are warped by the presence of the Earth, and, more profoundly, how the Earth’s rotation drags space-time around with it. These effects, though small for the Earth, have far-reaching implications for the nature of matter and the structure of the Universe.
The gyroscopes are contained in almost-perfect spheres fabricated to an amazing tolerance:
These spheres, the size of Ping-Pong balls, are the roundest objects ever made by man. The tiny spheres are enclosed inside a housing chamber to prevent disruption from sound waves, and chilled to almost absolute zero to prevent their molecular structure from creating a disturbance. The accuracy of these gyroscopes is 30 million times greater than any gyroscope ever built.
I think that this is a very cool experiment, one which will hopefully allow us to better understand some of the underlying physics governing our universe. The Gravity Probe B home page has a whole lot more information and links to other sites if you’re interested in more details.
