Invisible ‘dark radiation’ may explain a big problem with dark energy

There are hints that the universe may be behaving unexpectedly, and astrophysicists are racing to explain why. Their ideas to account for the surprising result include allowing dark matter and dark energy to interact, and arguing for the existence of strange “dark radiation” that is similar in nature to regular light but invisible.

In April, researchers using the Dark Energy Spectroscopic Instrument (DESI) in Arizona released the biggest 3D map of the universe ever created, and it hinted…