Virtual particles spontaneously pop in and out of existence in the vacuum — the Casimir effect proves this.

Operation CHAOS gathered intelligence on domestic protest movements in the 1960s.

Pianos have over 12,000 individual parts and are considered both string instruments and percussion instruments.

Particles can exist in multiple states until observed.

Extreme sports athlete Travis Pastrana became the first person to land a double backflip on a motorcycle at X Games 2006.

The printing press allowed books to be reproduced more efficiently.

Prehistoric cave paintings provide insight into early humans.

Synchronized skating — where teams of up to 20 skaters perform together — is a competitive discipline not yet in the Olympics.

An NBA basketball court is exactly 94 feet long and 50 feet wide.