pound of T.N.T. explodes would, if converted entirely into heat, raise the
temperature of 36 lbs. of water from freezing temperature (32 deg F) to
boiling temperature (212 deg F). The nuclear fission of a pound of uranium
would produce an equal temperature rise in over 200 million pounds of
water.

The explosive effect of an ordinary material such as T.N.T. is derived from
the rapid conversion of solid T.N.T. to gas, which occupies initially the
same volume as the solid; it exerts intense pressures on the surrounding
air and expands rapidly to a volume many times larger than the initial
volume. A wave of high pressure thus rapidly moves outward from the center
of the explosion and is the major cause of damage from ordinary high
explosives. An atomic bomb also generates a wave of high pressure which is
in fact of, much higher pressure than that from ordinary explosions; and
this wave is again the major cause of damage to buildings and other
structures. It differs from the pressure wave of a block buster in the
size of the area over which high pressures are generated. It also differs
in the duration of the pressure pulse at any given point: the pressure from
a blockbuster lasts for a few milliseconds (a millisecond is one thousandth
of a second) only, that from the atomic bomb for nearly a second, and was
felt by observers both in Japan and in New Mexico as a very strong wind
going by.

The next greatest difference between the atomic bomb and the T.N.T.
explosion is the fact that the atomic bomb gives off greater amounts of
radiation. Most of this radiation is "light" of some wave-length ranging
from the so-called heat radiations of very long wave length to the
so-called gamma rays which have wave-lengths even shorter than the X-rays
used in medicine. All of these radiations travel at the same speed; this,
the speed of light, is 186,000 miles per second. The radiations are