A great deal of physics understanding is required for the design and construction of thermonuclear weapons. Since the days of the Manhattan Project, physicists have relied on a combination of theory and experiment for the successful creation of nuclear weapons. One of the great experimental difficulties faced by the designers of nuclear weapons is that nuclear weapons operate in a high energy density regime not found on the earth except during a nuclear weapon detonation. Replicating these conditions is difficult unless a nuclear weapon is actually detonated. One of the reasons for the large number of expensive tests at the Nevada Test Site was that there was no other way to obtain the required data.