Re: What is the light loss rate in a box (mirror, etc) of ultraviolet light?

My, that's quite a bunch of questions you have asked. Let me try to take them one at a time...

if you created a light beam that matched the frequency of the mirror that was placed in front of it in a vacuum, and placed an identical mirror at the other end and aligned them so that they will reflect back and forth. Will there be any energy loss (at what rate is it lost (I read this in an article response)? If so, how much (I will then calculate the loss in energy (Percent or energy level, to see how long it will last)?

The amount of energy lost as the light bounces back and forth from mirror to mirror depends on a number of properties: the wavelength of the light, the composition and surface properties of the mirror, the angle of incidence, and so forth. It's a complicated issue. Fortunately, one of the other Mad Scientists has placed a very comprehensive discussion of the issues into the MadSci archive. If you go to the MadSci search page,

http://www.madsci.org/MS_search.html

and type into the Keywords Query box the words

mirror reflectivity

and click the "Submit Query" button, you will see a list of about 15 answers to questions about mirrors. One of them, written by Adrian Popa on the topic of two-way spherical mirrors, should provide good answers to your questions. You could also read the answers to some of the other questions which are returned by this query.

Your next question is

I have found contradicting data on the interaction of photons on each other. If two electrons bounce off each other, what happens? I have read that two beams of light hitting each other will at their incident angle disperse. However, will the photons lose energy?

I am guessing that you meant to type "If two PHOTONS bounce off each other" instead of "two ELECTRONS" in your question. If you really mean "electrons", then the answer depends: for collisions at low energies (meaning that the combined total energy of the electrons is too small to produce new particles; non-relativistic collisions, in short), you can use the laws of conservation of momentum and energy to figure out what will happen afterwards. Any good introductory physics textbook will have a chapter which discusses collisions and how to solve for the final trajectories of two particles, given their initial conditions. For collisions at very high energies, I'm afraid that there is no simple answer: once again, energy and momentum must be conserved, but in this case, new particles can be created, and the original electrons may be converted into energy or new particles.

So, assuming that you did mean to write "what will happen if two PHOTONS collide?", there is again a very nice discussion in the MadSci archives. If you search for keywords

photons collide

you will find, among the list of related answers, one by Phil Marsden. It is quite lengthy, since the result tends to depend on exactly what you mean by "interact" or "collide". Let me quote just a very small bit of Phil's discussion:

The simple answer to this question is that photons really do collide and interfere with each other they just do it very quickly and it is very difficult to detect. They do not scatter off each other however since they can only exchange energy and momentum when in a medium. .... The conclusion to all of this is that photons are quite strange and, although not like solid matter where you can easily see collisions and interactions, still can interact and influence each other, given the right circumstances.

I urge you to read all of Phil's discussion -- it helped ME to understand what can happen!

The final part of your question is

My next question is that what the best reflecter of light/Ultraviolet light is. I have read that snow is the best reflector of light. However, I am told to find out the next best light in respect to the spectrum of light that is (visible and ultraviolet) listed above. What is the best for this (Mirror, metal, glass, etc)?

I'm an astronomer, so I know a bit about mirrors used to reflect and focus visible light in telescopes. Snow is certainly a good reflector of light, but it's not the best one. You can see some measurements of the "albedo" of snow -- that means "the amount of light snow reflects" -- at these two URLs:

Optical Properties of Snow from the Airborne Visible/InfraRed Imaging Spectrometer at University of California, Santa Barbara.

Spectral Albedo Observation on the Snow Field at Barrow, Alaska from the Climate Monitoring and Diagnostics Laboratory of the NOAA

As you can see, snow reflects about 90 percent of incident light at wavelengths of 500 nm -- in the middle of the visible range -- but only about 75 percent at 1000 nm, in the near-infrared. That's pretty good, but not great; and just think how hard it would be to use a snow-mirror on a hot summer's night!

Astronomers typically make mirrors by shaping glass very carefully into a parabolic shape, and then coating its surface with a thin layer of some material. Some simple metal coatings do a very good job: silver and aluminum, for example. You can see graphs showing their reflectivity as a function of wavelength at

SNAP passbands: design and actual

Look at the section labelled "Reflectivity of the mirrors." You'll see that silver reflects more than 90 percent of the incident light throughout the visible and into the near-infrared. Its reflectivity drops sharply as one looks into the ultraviolet, though.

For some applications, scientists place a special, very very thin layer of material over the metallic coat. If one is interested in a rather narrow range of wavelengths, one can design what are called "interference coatings" which will reflect light in that range VERY well; the disadvantage is that they may reflect very poorly outside the range of interest. It is a very interesting problem to design a coating which will reflect (or NOT reflect) light of particular wavelengths. You can find a very simple introduction to the idea in university textbooks of physics: look for chapters on interference of light waves. You might also look at some of the notes for a course I teach:

Lecture notes on Thin Films

I hope that this information will help you. Remember that the MadSci Archives contain a great deal of information already, since there are many curious people in the world (and many knowledgeable scientists willing to provide answers).