China sends farthest 'unhackable' signal from space to Earth
Scientists in China have successfully used its quantum satellite to transmit 'entangled photons' covering a record distance of over 1,200 km from suborbital space to Earth. Photons are elementary particles of light which when entangled (paired) remain connected, implying changes in one affects the other, even if they are separated by huge distances, making the signal "unhackable".