Cooking soup, thermogram footage. Thermography records the temperature of surfaces by detecting long-wavelength infrared radiation. The colours show variations in temperature. The scale runs from white (warmest), through yellow, orange, red and purple to blue and black (coldest). This footage shows soup (orange and yellow) being heated in a pan, with bubbles forming (yellow). A spoon is used to stir the soup, bringing hotter liquid to the surface (yellow). The spoon (purple) and hand (black) used to taste the soup are colder than the soup.