general theory of relativity

Antimatter particles may be a lot more predictable than science fiction makes it out to be, responding to gravity just like regular matter.

Sinking Feeling

Astrophysicist Ron Mallett believes he's figured out how to build a time machine that would allow someone to travel to the past.

Last week, scientists achieved "first light" with the Mayall Telescope's Dark Energy Spectroscopic Instrument. It could teach us about dark energy.