The flow of time isn’t as consistent as we might think – gravity slows it down, so clocks on the surface of Earth tick slower than those in space. Now researchers have measured time passing at ...

In a first, researchers from the U.S. and Germany excite Thorium-229 in opaque material, advancing optical nuclear clocks.

Scientists are testing a novel way to measure cosmic expansion using time delays in gravitationally lensed quasars. Their ...

The white pickup truck pulls up to a decommissioned space observatory on top of Mount Blue Sky, one of Colorado’s famous “14ers,” mountains that reach more than 14,000 feet high. The scene is stark on ...