When the cosmic rays and gamma rays smash into molecules in the Earth's atmosphere, they set off a cascade of other fast-moving particles.

BBC: Hawc gamma-ray telescope captures its first image

Laser interferometers are looking for disturbances in their experimental set-ups that are equivalent to mere fractions of the diameter of a proton, one of the particles that make up the nucleus of an atom.

BBC: Lab tuned to gravity's 'ripples'