Electrophonic Explanation Difficulties
It was more than difficult, it was simply impossible for the anomalous sounds from bolides to be explained prior to the theoretical understanding of electromagnetic radiation by James Clerk Maxwell and the production of such radiation by Heinrich Hertz in 1888. After that vital discovery there still remained severe difficulties conspiring to frustrate those seeking a viable physical explanation of the phenomenon.
Here is a list of the six salient features of the anomalous sounds from bolides that needed to be explained by any successful investigator.
This is where matters stood prior to the resolution of the problem which stemmed from the investigation by Colin Keay of many reports describing a huge bolide which turned night into day over the Australian cities of Sydney and Newcastle, New South Wales, in the early hours of 1978 April 7.
- The anomalous sounds are very rare. Few people have ever heard them, and none ever had the good fortune to have a recording device to hand at the time the bolide was in view.
- The sounds are evidently capricious to the extent that not all witnesses in a group may hear them. Sometimes all will agree that sounds were audible. On the other hand only one or two members of a group may hear the sounds, and be ridiculed by the others.
- Propagation of the required energy is instantaneous, implying transmission at the velocity of light. But no electromagnetic disturbance had been known to produce sound except for electrostatic "brush discharges". Such discharges do not propagate over distances of up to 300 km, as often is necessary for the production of electrophonic bolide sounds.
- No electromagnetic disturbance had ever been detected from a bolide. This provoked at least one top meteor scientist, Gerald Hawkins, to declare that meteors (including bolides) "show a surprisingly low efficiency in converting kinetic to radio energy".
- The method of conversion of electromagnetic radiation into sound was quite obscure. It was generally held that a rectifier, such as a metal tooth filling, was needed to detect the sound.
- No physical mechanism was known for the production of strong electromagnetic radiation from bolides.
Despite the time, ninety minutes before sunrise, the New South Wales fireball was observed by thousands of eye-witnesses. It was a media sensation for almost a week. Some of those who heard its electrophonic sounds provided invaluable testimony to assist in studying the phenomenon.