Black-body radiation has a characteristic, continuous frequency spectrum that depends only on the body's temperature, called the Planck spectrum or Planck's law. The spectrum is peaked at a characteristic frequency that shifts to higher frequencies with increasing temperature, and at room temperature most of the emission is in the infrared region of the electromagnetic spectrum. As the temperature increases past about 500 degrees Celsius, black bodies start to emit significant amounts of visible light. Viewed in the dark, the first faint glow appears as a "ghostly" grey. With rising temperature, the glow becomes visible even when there is some background surrounding light: first as a dull red, then yellow, and eventually a "dazzling bluish-white" as the temperature rises.
This appearance is caused by a distribution of all wavelengths of light more or less based on temperature in blackbody radiation. In laser radiation, only a single frequency appears. Light from a infrared laser cannot be seen. The Rossi reactor may be acting like an infrared laser since few visible wavelengths are seen at 1400C,
