New research suggests that if dark matter is composed of "dark photons," it would not have heated the early cosmos like scientists previously thought. If correct, this discovery could represent a paradigm shift in the hunt for the universe's most mysterious stuff.
Dark matter remains so elusive because, despite outweighing the everyday matter that composes stars, planets, moons and our bodies by a ratio of five to one, it is effectively invisible. That is because it doesn't interact with light. And the fact that electrons, protons, and neutrons do interact with light (or, more accurately, electromagnetic radiation) has inspired the search for particles beyond the Standard Model of particle physics, leading to lots of hypothetical candidates for dark matter.
One of these candidates is the dark photon, the dark universe's version of a photon carrying a force other than electromagnetism, which is the responsibility of standard photons.
