It has now been more than one hundred years since Einstein published his General Theory of Relativity and nearly that long since an experiment measuring the deflection of starlight by the sun gave credence to it. Now, another experiment continues to confirm its continued relevance.
The General Theory of Relativity attempts to explain the phenomenon of gravity. Einstein postulated that gravity is the result of curvature in space-time caused by the mass of objects. His previous special theory of relativity had already equated space and time. Because of the curvature from gravity, Einstein further postulated that the shortest path for light to travel in the universe was not a straight line, but instead curved paths.
The General Theory of Relativity has often been placed at odds with the other major breakthrough in physics in the twentieth century: quantum mechanics. While relativity attempts to explain the macro universe, quantum mechanics explains the micro of what’s happening at the atomic and subatomic level.
One of the key aspects of the theory is known as the equivalence principle. That principle simply states that the mass of an object when acted upon by gravity is equivalent to the mass of an object when acted upon by another force, such as a push from a person. The principle was recently confirmed again by Italian scientists working with rubidium, who demonstrated that the gravitational pull on rubidium atoms was equivalent to the mass expected based upon quantum mechanics.
Although scientists have not been able to unify Einstein’s theories with quantum mechanics, experiments such as this one may bring them slightly closer to a general theory of how the universe functions.