The most distant X-ray jet in the Universe, from quasar GB 1428, helps illustrate how bright these fantastic objects are. If we can figure out how to use quasars to measure the expansion of the Universe, we can understand the nature of dark energy as never before. (X-RAY: NASA/CXC/NRC/C.CHEUNG ET AL; OPTICAL: NASA/STSCI; RADIO: NSF/NRAO/VLA)

Dark Energy May Not Be A Constant, Which Would Lead To A Revolution In Physics

A new study claims that dark energy is changing with time. Here’s what it would mean, if true.

For the past generation, we’ve recognized that our Universe is a particularly dark place. Sure, it’s filled with stars, galaxies, and a slew of light-emitting phenomena everywhere we look. But each and every one of the known processes that generate light is based on the particles of the Standard Model: the normal matter in our Universe. All the normal matter there is — protons, neutrons electrons, neutrinos, etc. — represents just 5% of what’s out there.

The other 95% is a dark mystery, but it can’t be any of the particles we know. According to our best measurements, 27% of the Universe is made of some type of dark matter, which doesn’t interact with light or normal matter in any known way. And the remaining 68% is dark energy, which appears to be a form of energy inherent to space itself. A new set of observations is challenging what we presently think about dark energy. If it holds up, everything we know will change.

Without dark energy, the Universe wouldn’t be accelerating. But to explain the distant supernovae we see, among other features, dark energy (or something that mimicks it exactly) appears to be necessary. (NASA & ESA, OF POSSIBLE MODELS OF THE EXPANDING UNIVERSE)