The Unruh effect (alternatively known as the Unruh-Davies-DeWitt-Fulling effect) was named after Canadian physicist W. G. Unruh.
It's a proposed prediction about temperature gains for a theoretical accelerating observer in a vacuum.
[…] in layman's terms, an accelerating thermometer (like one being waved around) in empty space, removing any other contribution to its temperature, will record a non-zero temperature, just from its acceleration."
Source : Wikipedia
The theoretical implications have been studied from 1973, and few quantum physicists currently dispute its potential possibilities.
To date, however, there is no experimental evidence that the effect is real.
For an extensive technical overview see : The Unruh effect and its applications Reviews of Modern Physics, APS