For many years, astrophysicists have theorized that an invisible material they call “dark matter” makes up the majority of the universe’s mass. Any behavior of objects in the universe that can’t be explained by ordinary mass — such as how galaxies rotate in space — could be due to the gravitational effects dark matter.
But now, a bold new theory from European researchers suggests a startling alternative: the strange behavior of galaxies could be due to the combined mass of untold zillions of photons, each of which has just a tiny bit of mass.
Conventional wisdom is that photons have zero mass (although that claim is complicated). But if each one had just a “vanishingly tiny” mass, according to a new paper published in The Astrophysical Journal, the combined effect could explain large-scale cosmic phenomena, including the rotation of galaxies.
“By assuming a certain photon mass, much smaller than the current upper limit, we can show that this mass would be sufficient to generate additional forces in a galaxy and that these forces would be roughly large enough to explain the rotation curves,” researcher Dmitry Budker, a professor at the Helmholtz Institute Mainz, said in a press release. “This conclusion is extremely exciting.”