A Force from Empty Space: The Casimir Effect
Credit & Copyright: Umar Mohideen (
U. California at Riverside)
Explanation: 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.