News

Astronomy

Stellar speed limit

Ripples in the fabric of space-time may put the brakes on the fastest-spinning stars in the universe and prevent them from flying apart.

Earth

Not So Green? Using hydrogen as fuel may hurt environment

Replacing fossil fuels with clean-burning hydrogen—considered to be a way to reduce globe-warming carbon dioxide—may create a different set of environmental problems, including larger and longer-lasting ozone holes.

Humans

Small World After All: Short e-mail chains reach targets worldwide

A large-scale study of e-mail users has borne out the notion that one person on the planet can reach any other person through a chain of about six social ties.