The idea that everything that exists can be built from the bottom up has long held sway among physicists. Now, a new kind of ...

Explore 25 thought experiments that challenge reality, from simulations to brains in vats. Question existence, identity, and ...

Curiosity has detected a surprising variety of organic molecules on Mars, including compounds tied to the chemistry of life.

A molecule so small it could fit on a Post-it note of genetic code has just pulled off something scientists have chased for ...