Nuclear reaction energy transfer

[Pengwuino]

Ok i have a question that I've been wondering about for a while here...
One of my chemistry professors stated to the class that E=mc^2 means that energy is transferred through light, sound, and heat. Now i was under the impression that 1, heat is light... and sound was simply particle movements.
Now I am confused as to exactly what happens in a nuclear bomb. You see light... you see sound waves (detect)... and there's the big fireball (and I also want to know what exactly that fireball is on a molecular level). What determines how much energy is dispersed for each mechanism and exactly what kind of energy is being transmitted in the first place?
Kind of a confusing question... because I am kinda confused :)

 

[pervect]

It's a rather complicated process, I would suggest that you might find

http://nuclearweaponarchive.org/Nwfaq/Nfaq5.html

interesting. Especially the following section

5.3.1.1 The Early Fireball

Immediately after the energy-producing nuclear reactions in the weapon are completed, the energy is concentrated in the nuclear fuels themselves. The energy is stored as (in order of importance): thermal radiation or photons; as kinetic energy of the ionized atoms and the electrons (mostly as electron kinetic energy since free electrons outnumber the atoms); and as excited atoms, which are partially or completely stripped of electrons (partially for heavy elements, completely for light ones).

Thermal (also called blackbody) radiation is emitted by all matter. The intensity and most prevalent wavelength is a function of the temperature, both increasing as temperature increases. The intensity of thermal radiation increases very rapidly - as the fourth power of the temperature. Thus at the 60-100 million degrees C of a nuclear explosion, which is some 10,000 times hotter than the surface of the sun, the brightness (per unit area) is some 10 quadrillion (10^16) times greater! Consequently about 80% of the energy in a nuclear explosion exists as photons. At these temperatures the photons are soft x-rays with energies in the range of 10-200 KeV.

The first energy to escape from the bomb are the gamma rays produced by the nuclear reactions. They have energies in the MeV range, and a significant number of them penetrate through the tampers and bomb casing and escape into the outside world at the speed of light. The gamma rays strike and ionize the surrounding air molecules, causing chemical reactions that form a dense layer of "smog" tens of meters deep around the bomb. This smog is composed primarily of ozone, and nitric and nitrous oxides.

X-rays, particularly the ones at the upper end of the energy range, have substantial penetrating power and can travel significant distances through matter at the speed of light before being absorbed. Atoms become excited when they absorb x-rays, and after a time they re-emit part of the energy as a new lower energy x-ray. By a chain of emissions and absorptions, the x-rays carry energy out of the hot center of the bomb, a process called radiative transport. Since each absorption/re-emission event takes a certain amount of time, and the direction of re-emission is random (as likely back toward the center of the bomb as away from it), the net rate of radiative transport is considerably slower than the speed of light. It is however initially much faster than the expansion of the plasma (ionized gas) making up the fireball or the velocity of the neutrons.

An expanding bubble of very high temperatures is thus formed called the "iso-thermal sphere". It is a sphere were everything has been heated by x-rays to a nearly uniform temperature, initially in the tens of millions of degrees. As soon as the sphere expands beyond the bomb casing it begins radiating light away through the air (unless the bomb is buried or underwater). Due to the still enormous temperatures, it is incredibly brilliant (surface brightness trillions of times more intense than the sun). Most of the energy being radiated is in the x-ray and far ultraviolet range to which air is not transparent. Even at the wavelengths of the near ultraviolet and visible light, the "smog" layer absorbs much of the energy. Then too, at this stage the fireball is only a few meters across. Thus the apparent surface brightness at a distance, and the output power (total brightness) is not nearly as intense as the fourth-power law would indicate.

There is much more, I just thought I would quote some of the relevant section to aid you in seeing if you were interested in reading the whole article.