Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!watmath!clyde!burl!mgnetp!ihnp4!houxm!vax135!cornell!uw-beaver!tektronix!hplabs!sri-unix!Shinbrot.WBST@XEROX.ARPA From: Shinbrot.WBST@XEROX.ARPA Newsgroups: net.physics Subject: Re: passing water Message-ID: <13195@sri-arpa.UUCP> Date: Thu, 6-Sep-84 09:36:00 EDT Article-I.D.: sri-arpa.13195 Posted: Thu Sep 6 09:36:00 1984 Date-Received: Wed, 12-Sep-84 02:51:46 EDT Lines: 19 Well, I'm no expert on transmission through water, but since nobody else has addressed the question, I'll have a go. Water severely attenuates all but extremely low frequencies (ELF). As a result, submarines have to surface to get information - a considerable hazard in military environs, obviously. The US Navy has attempted to resolve this issue by proposing an ELF transmitting station in the continental US. Almost by default, they decided upon Michigan as a likely broadcasting station. You may have heard in popular or scientific press the controversy surrounding ELF there, for ELF is reported to cause a variety of health problems. IN any case, the crux of the biscuit is that ELF can be transmitted through water where little else except neutrinos can pass. ELF obviously requires a correspondingly extremely large broadcasting antenna (c = f(lambda)). The curious thing to me in all of this is how the pentagon envisages receiving these waves. Perhaps making extremely long submarines??? - Troy