WIRELESS ECHOES

Sun (Auckland), Volume III, Issue 795, 16 October 1929, Page 16

WIRELESS ECHOES

BEYOND THE MOON PENETRATING SHORT WAVES On February 29 of last year Professor Stormer, the well-known Scandinavian authority on the aurora borealis, received a remarkable communication from Mr. Jorgen Hals, an engineer, of Oslo. It announced that, when he was listening to the shortwave wireless signals emitted by the Dutch station PCJJ (Eindhoven) he heard two echoes of each signal. One was the well-known repetition of the signal after circling the earth —which it does in one-seventh of a second — while the other was of unknown origin, and occurred three seconds afterward. On receipt of that letter Professor Stormer organised a series of systematic observations of the new phenomenon, with the help of Dr. van der Pol, of Philips Radio, Eindhoven. The experiments took place in the summer of 1928, and very powerful signals were employed, in the form of undamped waves 31.4 metres long. Echoes were heard in Norway and Holland varying between three and fifteen seconds after the main signal, the average interval being eight seconds. Sometimes two echoes were heard within an interval of about four seconds. The strength of these echoes was estimated at between one-tenth and one-twentieth of the main signal. 800,000 MILES AWAY

Having established the facts, it remained to find an explanation. Now it must be remembered that the Eindhoven signals were electric vibrations, inaudible a few yards from the station. They were received instantaneously by telephone. They were received again after they had circled the earth with a speed of 186,000 miles a second. They were received again after about eight seconds, just as if they had been reflected by an object 800,000 miles away. What is this object, and where is it? The nearest object known to us in space is the moon, which is 240,000 miles away. Electric waves would travel to the moon and back in two and a-half seconds. The object or objects must, therefore, be situated beyond the moon’s orbit. Now, as far as we know, the space between us and the moon, as well as the space beyond, does not contain any visible or ponderable matter, so an ordinary material object must be excluded. We must find an imponderable structure which is capable of reflecting electric waves. Professor Stormer finds such structures in the streams of electrons issuing from the sun, which cause auroras and magnetic storms on earth. Another explanation has been put forward by Dr. van der Pol, who believes the signals get entangled in the Heaviside layer, a layer of ionised air some twenty miles up, which is known to facilitate the transmission of short-wave signals. At a certain degree of ionisation the speed of waves becomes very small, and they may emerge again after a considerable interval. “FEELING ABOUT IN THE DARK” A mathematical discussion of the whole subject appears in a paper communicated to the Danish Royal Society by Principal Pedersen, of the Technical College, Copenhagen. In this paper Pedersen proves that the long-delayed echoes cannot- arise either by propagation of radio waves within the earth’s atmosphere or by the waves travelling outside the latter in a strongly ionised medium. They are due to the fact that the waves have travelled very great distances outside the earth’s atmosphere and have then been reflected by swarms or bands of electrons in space, as assumed by Stormer. It is a reasonable assumption that ail waves shorter than about eight metres will penetrate into space with very little attenuation, whereas waves 70 metres long will be completely reflected back to earth even at midnight. Echoes occurring later than ten seconds cannot be due to the propagation of waves within the atmosphere. They must encounter some obstacle far outside the earth. One thing is certain. We have in the short wireless wave a new probe of extraordinary penetrating power. Nobody knows as yet where its limitations are or what it is destined to reveal. We are like a blind man who has just acquired the use of his fingers, and who is feeling about in the dark. MORE DINNER MUSIC SESSION AT 4YA It is announced that with the inauguration of the new station at 4YA, Dunedin, a dinner music session will be started tomorrow evening.