Somebody who wants to nab dissidents can send lots of data to the computer running hidden services, heat it up, take a measurement, and then compare those measurements to other computers in the Tor network. Once she has a match, that person will know the IP address of the computer hosting the formerly-anonymous publisher. She can now track the computer down and destroy it. Murdoch speculated that time skew might also reveal the whereabouts of a computer because one could figure out what time of day air conditioning got turned on and off, or when sun was heating up the room where the computer is located. One could also figure out, based on the heat signature, whether a computer was stored in a rack or under somebody's desk.