NOT PRACTICABLE

Gisborne Herald, Volume LXVI, Issue 20128, 23 December 1939, Page 13

NOT PRACTICABLE

DEATH RAYS NATURAL LAWS OPERATE DIFFUSION CURBS USE NEW YORK, Dec. 1. London and Paris have reports that Adolf Hiller possesses a ray to stop airplane engines—and the death ray story is revived in the United States, but none of these reports, now or in the past, has mentioned the one significant fact that would make the claims plausible to scientists. None tells how they plan to avoid Nature’s inverse square law of dissipation of energy, which includes rays of all kinds whatsoever, when travelling in space. This law was explained by Dr. Alfred N. Goldsmith, of New York, a widely known radio authority and engineer. He described exactly the ray which would bring down warplanes and the prosaic handicaps which would render it impracticable. Under the inverse square law, energy decreases in intensity in incerse proportion to the distance it travels. It is like gravitation. Example of the Sun

The commonest example is the sun. On the planet Mercury sun rays would melt lead; on earth, at about three time Mercury’s distance from the sun. only butter. Yet rays reaching the earth are individually exactly as strong as on Mercury, or as at the instant of leaving the sun. They spread as they travel, and that accounts for their ever growing weakness with distance. When' distance doubles, rays must spread over four times more space; when it triples, through nine times as much. This is true also when light or heat is focussed in a beam. Beam rays are never parallel, never the endless pencil-shape of comic thrillers. They travel in always widening cones.

This cone is true of all other kinds of rays, whether X-rays, ultra-violet, infra-red, radio, electron or less well known varieties. The problem, then, is to find what rays can be projected a military distance. Immediately, all rays, except a narrow band of radio, are ruled out by two other conditions. One is the absorption, or blanketing effect of air on all the short wave rays, which means all kinds except radio. Radio Waves Air does not stop radio waves. But the huge wave lengths of all but the shortest radio waves make it impracticable to convert them into beams. A reflector would have to be miles in diame'er to focus many of the common radio waves. In the micro radio range, which is one millimetre to one metre wave lengths, reflectors are, possible, with diameters of 2ft. to 200. A beam of Ihese could be projected against a distant plane. The beam would have to be strong enough to cause sparks or to melt ignition wires. It would have to do this after passing through shielding, already common on motors. Assume a reasonable thickness of shielding, of one-eighth of an inch of aluminium. Make it effective on a plane distant 21,000 ft. Undfer the losses of the inverse square law, this ray would have to start with almost incredible power. The necessary power would be enough to penetrate 400 ft. of aluminium 100 ft. away. This apparently means several Niagaras of power to project a single effective ray to a good military distance. Leaving out the question of where to obtain such power, the ray would still be impracticable, because some of the power would penetrate whatever protective shielding surrounded the generator and make it impossible for men to be anywhere near.