clipped from: space.newscientist.com   

The mysterious cosmic presence called dark energy, which is accelerating the expansion of the universe, might be lurking in hidden dimensions of space. The idea would explain how these dimensions remain stable – a big problem for the unified scheme of physics called string theory.

Ever since astronomers discovered in the mid-1990s that other galaxies are accelerating away from us, physicists have struggled to explain why.
Even though the vibration is imprisoned in these other dimensions, it can extend its gravitational influence into our space. Its gravity is also repulsive in our space, just like the "ordinary" cosmological constant, so it would cause cosmic acceleration.

If Adelberger's pendulum does start to see gravity grow below 0.01 millimetre, it could be a sign that Greene and Levin are right, and the force that's tearing our universe apart really is an invader from another dimension.