Few maps are made of where the mines are laid, and since the home-made varieties contain very little metal, they are extremely difficult to detect and so sensitive that even sniffer dogs can detonate them.

BBC: Farc rebels have been fighting the government for decades

For example, most of the energy from supernovae is thought to be carried away by neutrinos -- the lightweight, difficult-to-detect particles that are so important to understanding the fundamental laws of nature.

CNN: Why gamma-ray burst shocked scientists