1. In physics, a black body is an idealized object that absorbs all electromagnetic radiation that falls on it. No electromagnetic radiation passes through it and none is reflected. Because no light (visible electromagnetic radiation) is reflected or transmitted, the object appears black when it is cold. However, a black body emits a temperature-dependent spectrum of light. This thermal radiation from a black body is termed black-body radiation. # Studying the laws of the black body historically led to quantum mechanics # Blackbody radiation is light in thermal equilibrium, light radiation with a given temperature. It is the basic thermodynamic state of light. Because light is the oscillation of a continuous electromagnetic field, the study of blackbody radiation reveals how continuous fields can have a temperature, something which contradicts classical physics. Because the thermal state of light was so confusing before the advent of quantum mechanics, the 19th century arguments that light has a thermal equilibrium state were made very carefully. # Today the black-body cavity may be thought of as containing a gas of photons # An almost perfect black-body spectrum is exhibited by the cosmic microwave background radiation., Hawking radiation is the hypothetical black-body radiation emitted by black holes. !!! # Super black is an example of such a material, made from a nickel-phosphorus alloy. More recently, a team of Japanese scientists discovered a material even closer to a black body, based on single-walled carbon nanotubes (SWNTs), which absorbs between 97% and 99% of the wavelengths of the light that hits it.
http://en.wikipedia.org/wiki/Black_body 2. Max Laue (who won the Nobel Prize in Physics in 1914 ) called the model of a black body as the ‘ Kirchhoff's vacuum.’ 3. And I have naive question: Can a ideal black body be model of real Vacuum T= 0K ? ========== . --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Epistemology" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/epistemology?hl=en -~----------~----~----~----~------~----~------~--~---
