A Force from Empty Space: The Casimir Effect

This tiny ball provides evidence that the universe will expand forever.
Measuring slightly over one tenth of a millimeter, the ball moves toward
a smooth plate in response to energy fluctuations in the vacuum of empty
space. The attraction is known as the Casimir Effect, named for its
discoverer, who, 50 years ago, was trying to understand why fluids like
mayonnaise move so slowly. Today, evidence is accumulating that most of
the energy density in the universe is in an unknown form dubbed dark energy.
The form and genesis of dark energy is almost completely unknown, but
postulated as related to vacuum fluctuations similar to the Casimir Effect
but generated somehow by space itself. This vast and mysterious dark energy
appears to gravitationally repel all matter and hence will likely cause the
universe to expand forever. Understanding vacuum fluctuations is on the
forefront of research not only to better understand our universe but also
for stopping micro-mechanical machine parts from sticking together.