Universe Might Weigh Much Less than We Think

Meet the New, Slimmed-Down Universe

The universe might be many billions of light-years wide, but it could be much lighter than its proportions would lead you to believe, according to new research from the University of Alabama at Huntsville (UAH).

In fact, the UAH research team's findings indicate the universe's mass might be 10 to 20 percent less than previous calculations indicated.

The sudden slimdown comes from new information about the source of x-ray energy radiating from the middle of galaxy clusters, which are the largest cosmological structures in the universe. UAH researchers had previously theorized that both low- and high-energy x-rays came from intergalactic clouds of so-called "warm" gas. However, they now believe the low-energy x-rays might be created in collisions between photons and electrons; the energy generated in those collisions revs up the photons, which are electromagnetic particles, from microwaves to x-rays.

The discovery is like finding out that the many points of light you thought were coming from aircraft carriers were instead generated by light, tiny but very bright fireflies.

"This means the mass of these x-ray emitting clouds is much less than we initially thought it was," said Max Bonamente, an assistant professor in UAH's physics department. "A significant portion of what we thought was missing mass turns out to be these 'relativistic' electrons."

UAH researchers in 2002 had speculated that some of the "missing mass" needed to hold the universe together gravitationally came from x-ray emitting gases in the middle of galaxy clusters. While those gases were believed to be present in amounts less than one atom per cubic meter, spread out over the vast reaches of the universe, they could have accounted for up to 10 percent of the mass and gravity required to bind together galaxies, galaxy clusters and more.