An example of simile and metaphor in popular science writing:
"The high-energy clacium atoms were blasted with a pair of lasers, which knocked some of the atoms up into a higher energy state. Soon after, the atoms would drop back down, giving off a photon of light. This is much the same process as happens in ordinary reflection of light. But every once in a while, instead of one photon, two were given off, each of lower energy. These two photons were 'born' entangled, the optical equivalent of twins."
Brian Cleggs
Clegg, B. (2015). Light Years. The extraordinary story of mankind' fascination with light. Icon.
Note: the atoms were not literally knocked up, and did not literally drop down – though this metaphorical use of up and down is so commonplace (a team moves up the league) it might be considered 'dead' metaphor.
Read about examples of science similes
