Science: Don’t Look Now

Sightseeing during an atomic bombing is unwise; it may destroy the sight of anyone who is otherwise safe from the heat and blast. This is the warning of Ophthalmologist Heinrich W. Rose and Biophysicist Konrad Buettner, who looked into the matter at the Air Force School of Aviation Medicine.

In the case of a “nominal” (Nagasaki-type) atomic bomb, the heat cooks the skin up to two miles away. But if a person happens to be looking at the detonation, he will certainly be blinded permanently at more than four miles away, and even at a greater distance his eyesight will be seriously damaged.

The cause is a simple optical principle. The burning effect of the bomb’s heat on exposed skin diminishes as the square of the distance (twice as far away, it is one-fourth as strong). But the eye is a lens that concentrates heat and light in a spot on the retina. As distances increase, the spot grows smaller but remains as bright. At four miles away, a nuclear fireball 90 feet across forms a brilliant spot on the retina 1/300th of an inch in diameter. This is larger than the fovea centralis, the part of the retina that is used in accurate vision.

At four miles, enough heat will be concentrated on this area to cook the tissue, which will turn to something like hard-boiled white of egg. The immediate effect will be a large blind spot. Then, as inflammation spreads, the eye will lose its sight entirely. At night, when the pupil is wide open, blinding will occur at 25 miles or more.

If the atomic sightseer happens to be looking to one side of the fireball, his blind spot will not cover the center of his visual field, and the blindness is less likely to be permanent. But even off-center views of the bomb will make him partially or temporarily blind.

No count was made of people blinded at Hiroshima and Nagasaki; perhaps few people were looking into the sky at the right moment. If modern bombs attract more sightseers, they will blind them at greater distances than four miles, for they are far brighter than the nominal bombs were. Hydrogen bombs, say Drs. Rose and Buettner, will probably blind from as far away as they can be seen at all.