The tiny ball in the image provides evidence that the universe will expand ad inifinitum.
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 Dutch discoverer, who, 50 years ago in 1948, was trying to understand why certain fluids move too slowly!
In quantum field theory the vacuum expectation value (also called condensate) of an operator is its average, expected value in the vacuum. One of the best known examples of the vacuum expectation value of an operator leading to a physical effect is the Casimir Effect. It is also important in spontaneous symmetry breaking.
The Higgs field, of which the Higgs boson or God Particle is one component, has a vacuum expectation value of 246 GeV or 246 Billion electron Volts! 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 is likely to 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 in the emerging field of nano-technology.