Neutron stars are some of the densest objects in the universe. They are the core of a collapsed megastar that went supernova, ...

Sound waves are vibrations that are passed on between particles. The speed of sound is the distance a sound travels divided by the time it takes.

A person fires a starting pistol. A distant observer stood 200 metres away (measured using a 20 m tape measure or trundle wheel) records the time between seeing the flash of light from the ...