I think a black-body is a model of an object. For me that means it has a sort of surface and all light falling on that surface will not appear on another site of the object. The surface emits only radiation caused by the temperature within the object. This means a black-body is not transparent. A vakuum is a model of the state of space between objects. Don't know it there is space at all without objects. A vakuums should be transparent for radiation. Kurt
On 21 Jun., 22:26, socratus <[email protected]> wrote: > 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 -~----------~----~----~----~------~----~------~--~---
