How ghost hunters use Infrared Thermometers?

How do infrared (IR) thermometers work?

IR thermometers capture the invisible infrared energy naturally emitted from all objects. Infrared radiation is part of the electromagnetic spectrum which includes radio waves, microwaves, visible light, ultraviolet, gamma, and X-rays. Any object warmer than absolute zero emits energy somewhere within that range.

How does this apply to ghost hunting?

IR thermometers read the surface temperatures of things. The wall below is giving off a infrared heat signature of 78 degrees and the IR thermometer picks it up. If something invisible to the naked eye gets in between the wall surface and the thermometer and it has a lower you IR heat signature you will get a colder temperature reading. This is