At the heart of Einstein’s theory of gravity (general relativity) is the equivalence principle. The equivalence principle says that there is no difference between being stationary and subject to ...

For the first time in space, scientists have produced a mixture of two quantum gases made of two types of atoms. Accomplished with NASA's Cold Atom Laboratory aboard the International Space Station, ...

Since Galileo Galilei and Newton, the assumption is valid that inert and heavy mass are equivalent. This is, however, questioned by new physical theories such as the String theory. Now, the ...

One way to explain the puzzling acceleration of the universe is to modify Einstein’s theory of general relativity to create a fifth force that can account for the acceleration. These theories have to ...

If you simultaneously drop a feather and a bowling ball in a vacuum, they’ll hit the ground at the same time. In other words, despite their mass, they’re affected by a gravitational field in exactly ...

In the late 1500s, the Italian scientist Galileo Galilei conceived of an experiment that changed a foundation of physics. He mulled — and by some accounts actually tested — what would happen if two ...

How Einstein's equivalence principle extends to the quantum world has been puzzling physicists for decades, but a research team has now found the key to this question. How Einstein's equivalence ...

Scientists from Garching and Tuebingen investigated the equivalence principle for two different rubidium isotopes with an atom interferometer, a quantum mechanical device. They stored a billion ...

One of the most counter-intuitive notions in physics is that all objects fall at the same rate, regardless of mass, aka the equivalence principle. This was memorably illustrated in 1971 by NASA Apollo ...

The physics of the microrealm involves two famous and bizarre concepts: The first is that prior to observation, it is impossible to know with certainty the outcome of a measurement on a particle; ...