Scientists say 20 percent of the universe is missing

The same UAH group that found what was theorized to be a significant fraction of the "missing mass" that binds together the universe has discovered that some x-rays thought to come from intergalactic clouds of "warm" gas are instead probably caused by lightweight electrons.

If the source of so much x-ray energy is tiny electrons instead of hefty atoms, it is as if billions of lights thought to come from billions of aircraft carriers were found instead to come from billions of extremely bright fireflies.

"This means the mass of these x-ray emitting clouds is much less than we initially thought it was," said Dr. Max Bonamente, an assistant professor inUAH's Physics Department. "A significant portion of what we thought was missing mass turns out to be these 'relativistic' electrons."Traveling at almost the speed of light (and therefore "relativistic"), these feather weight electrons collide with photons from the cosmic microwave background. Energy from the collisions converts the photons from low-energy microwaves to high-energy x-rays.