The same formula also reveals the time it would take liquid deuterium to ignite at higher temperatures, the increase of which shortens the ignition time. These figures show that the ignition time for liquid deuterium at 75,000,000 degrees centigrade is 40 microseconds. At 100,000,000 degrees the time is 30 microseconds; at 150,000,000 degrees, 15 microseconds; and at 200,000,000 degrees on the centigrade scale, about 4.8 millionths of a second. Doubling the temperature speeds up the ignition time for liquid deuterium by a factor of about six. The problem thus is a dual one: to raise the temperature at which the A-bomb explodes, and to extend the time before the A-bomb flies apart. It is also obvious that if the liquid deuterium is to be ignited at all, it must be done before the bomb has disintegrated—that is, during the incredibly short time interval before it expands into a cloud of vapor and gas, since by then the deuterium would no longer be liquid. Can we increase the A-bomb’s temperature fourfold to 200,000,000 degrees and literally make time stand still while it holds together for nearly five millionths of a second? To get a better understanding of the problem we must take a closer look at what takes place inside the A-bomb during the infinitesimal interval in which it comes to life. This life history of the A-bomb is an incredible tale, from the time its inner mechanisms are set in motion until its metamorphosis into a great ball of fire. As explained earlier, the A-bomb’s explosion takes place through a process akin to spontaneous combustion as soon as a certain minimum amount (critical mass) of either one of two fissionable (combustible) elements—uranium 235 or plutonium—is assembled in one unit. The most obvious way it takes place is by bringing together two pieces of uranium 235 (U-235), or plutonium, each less than a critical mass, firing one of these into the other with a gun mechanism, thus creating a critical mass at the last minute. If, for example, the critical mass at which spontaneous combustion takes place is ten kilograms (the actual figure is a top secret), then the firing of a piece of one kilogram into another of nine kilograms would bring together a critical mass that would explode faster than the eye could wink—in fact, some thousands of times faster than TNT.