The Microscope, a French-built orbiter seeking to poke a hole in Einstein's theory of general relativity
Also on board the Soyuz will be Microscope, designed to test a key component in the theory of general relativity published by Albert Einstein 100 years ago. (READ: Space probe set to test Einstein's relativity theory)More specifically, the equivalence principle states that "the gravitational "force" as experienced locally while standing on a massive body (such as the Earth) is actually the same as the pseudo-force experienced by an observer in a non-inertial (accelerated) frame of reference", or that there is no way to distinguish between gravity and acceleration without outside knowledge. Einstein was never able to prove it, but their numerical equivalency is the basis of general relativity.
The 130-million-euro satellite will probe – with 100 times more accuracy than has been possible on Earth – the so-called "equivalence principle," which says that a feather in a vacuum should fall at the same speed as a lead ball.
The experiment will compare the motion of two different objects "in almost perfect and permanent free fall" aboard the orbiting satellite, according to France's CNES space agency, which financed 90% of the project.I'm betting on Einstein. So far, it's been a pretty good bet.
If any difference in motion is observed, the equivalence principle would collapse – "an event that would shake the foundations of physics," it states on its website.
Such a result would suggest that Einstein's relativity theory may be flawed. This would be a great relief to physicists who have long struggled to explain why the theory cannot be reconciled with quantum physics, the other pillar of modern physics.
"We shall then know that Einstein's theory of general relativity is not the whole story of gravity – that there are other forces contributing to it," French physicist Thibault Damour told reporters in Paris last week.
"It will not mean that Einstein's theory is completely wrong – just incomplete," he added.