called blackbody such because it absorbs all fall on him (or rather it) radiation in the visible spectrum and beyond.But if the body is not heated, the energy is re-emitted back.This radiation emitted by a black body, is of particular interest.The first attempts to study its properties have been done even before the emergence of the model itself.
In the early 19th century, John Leslie experimented with different substances.As it turned out, not only the black soot absorbs all of the incident visible light on it.She radiated in the infrared range is much stronger than the other, lighter substances.This was heat radiation which is different from all other types of multiple properties.Blackbody radiation equilibrium, homogeneous, there is no transfer of energy and depends only on the temperature of the body.At a sufficiently high temperature the thermal radiation of the object is visible and when any body, including blackbody, acquires color.
This unique object that emits only a certain kind of energy, could not help but attract attention.Since this is a thermal radiation, the first formulas and theories as to how the spectrum should look like, it has been proposed as part of thermodynamics.Classical thermodynamics is unable to determine at what wavelength should be a maximum of radiation at a given temperature, in what direction and how it will move during heating and cooling.However, it was not possible to predict what the distribution of the energy spectrum of a blackbody at all wavelengths, and in particular in the ultraviolet range.
On representations of classical thermodynamics, energy can be emitted by any amounts, including arbitrarily small.But to a black body would emit at shorter wavelengths, the energy of some of the particles must be very large, and in the VHF she went to infinity.In reality, this is impossible, infinity appeared in the equations and is called ultraviolet catastrophe.Only the theory of Planck that the energy can be emitted in discrete portions - quanta - has helped to resolve the difficulty.Today's thermodynamic equations are special cases of the equations of quantum physics.
Originally a black body representing the cavity with a narrow opening.The radiation from the outside gets into a cavity and absorbed by the walls.In the emission spectrum, which should have a black body, in this case, similar to the spectrum of radiation from the entrance to the cave, the opening of the well, the window into the dark room on a sunny day, etc.But most of them coincide with the spectra of the relic radiation of the universe and the stars, including the sun.
It's safe to say that the more a particular object of particles with different energies, the more it will resemble blackbody radiation.The curve of the energy distribution in the spectrum of blackbody reflects the statistical laws of these particles in the system, with the only difference that the energy transmitted in the discrete interactions.