Starts With A Bang

Could Dark Energy Be Caused By A Reaction To What’s In The Universe? (Synopsis)

The full UV-visible-IR composite of the XDF; the greatest image ever released of the distant Universe. Every galaxy shown here will eventually accelerate away from us at greater than the speed of light, thanks to dark energy. Image credit: NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI).

“Another very good test some readers may want to look up… is the Casimir effect, where forces between metal plates in empty space are modified by the presence of virtual particles.” -Gordon Kane

If you ask what the zero-point energy of space itself is, you can sum up all of the quantum fluctuations you can that arise in quantum field theory, and arrive at an absurd answer: 120 orders of magnitude greater than the observed. Yet if you assume that there’s an incredible cancellation and you get exactly zero, that removes the one thing our Universe needs to explain its expansion: dark energy.

The four possible fates of our Universe into the future; the last one appears to be the Universe we live in, dominated by dark energy. Image credit: E. Siegel.

Yet the Universe has matter, radiation, the Hubble horizon and other forms of artificial boundaries in it, and we know that boundaries (like metal plates in electromagnetism) can cut off some of the allowed modes of quantum fluctuations, and lead to a real force: the Casimir effect. Could this same effect — which exists for all the forces, not just electromagnetism — be responsible for dark energy?

An illustration of the Casimir effect, and how the forces on the outside of the plates are different from the forces on the inside. Image credit: Wikimedia commons user Emok, under a c.c.a.-by-s.a.-3.0 license.

Come find out what the possibilities are over at Starts With A Bang today!