The technique relies on the ability of energy to "flip bits" in memory. While cosmic rays very occasionally can cause a random bit in memory to change value, from 0 to 1 or from 1 to 0, Govindavajhala decided not to wait. He used a lamp to heat up the chips inside a computer and cause one or more bits of memory to change.
By doing so, the researcher broke the security model virtual machines rely on: that the computer faithfully executes its instruction set.