1. Seeing Red (Temperature & Radiation)

'Nothing tends so much to the advancement of knowledge as the application of a new instrument'. - Sir Humphrey Davy (British chemist)

Infra-red light may feel hot, but Infra-red is NOT a kind of heat. This “heat” misconception results from the idea that heat and light radiation are different: 'Heat radiation' is simply a 'colour' of light that is invisible to human beings. The idea of 'Invisible light' may seems bizarre and mysterious, but “invisibility” is caused by limited sensitivity of the human eye. If humans could see all the light in the IR spectrum, we would say things like this: “of course the electric heater makes things hot at a distance, it is intensely bright, and bright light can heat up any surface which absorbs it.”

Investigating Heat Using Infra-red Technology:

Infra-red radiation (IR) is emitted by all objects with a temperature above absolute zero according to the black body radiation law, making it possible (with the right instruments) to see one's environment with or without visible illumination.

The amount of radiation emitted by an object increases with temperature: When viewed through a thermal imaging camera, warm objects stand out well against cooler backgrounds. As a result, infra-red and similar heat-related photography (thermography) is widely used in cameras designed for security, industrial trouble-shooting and health diagnostics.

For example, government, airport and medical staff used thermography to detect suspected swine flu cases and prevent spread of the disease during the 2009 Swine Flu pandemic. Source: https://en.wikipedia.org/wiki/Thermography