Re: Radiation above gamma ray?
From: Gregory L. Hansen (glhansen_at_steel.ucs.indiana.edu)
Date: 10/19/04
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Date: Tue, 19 Oct 2004 15:30:05 +0000 (UTC)
In article <cl3a6a$e5n$1@reader1.panix.com>,
Paul Ciszek <nospam@nospam.com> wrote:
>
>In article <6bd4a4d3.0410190247.765c07e3@posting.google.com>,
>Pascal Damian <pascaldamian@icqmail.com> wrote:
>>nospam@nospam.com (Paul Ciszek) wrote in message
>>news:<cl1ptv$ml$1@reader1.panix.com>...
>>> In article <6bd4a4d3.0410180724.2bb1ce45@posting.google.com>,
>>> Pascal Damian <pascaldamian@icqmail.com> wrote:
>>> >Is electromagnetic radiation with wavelength shorter than the gamma
>>> >band impossible theoretically, or is it just because we cannot observe
>>> >them?
>>>
>>> According to one source, any photon with more than 100keV of energy is
>>> a gamma ray--whether it can be observed or not. If anyone has coined
>>> a term for a higher energy region of the electromagnetic spectrum, I
>>> have not heard of it. So, by default everything from some lower bound
>>> on upward is called a gamma ray, and there is by definition no such
>>> thing as "radiation above gamma rays".
>>
>>Ah, thanks for the clear-up. So similarly there's no "lower than radio waves".
>
>There are systems that use audio (and lower?) frequency EM waves for
>comunication. The people who design, build, or use these systems might
>have specific names for parts of the spectrum below what is usually
>considered radio waves.
http://www.wordiq.com/definition/Super_low_frequency
ULF - Ultra Low Frequency, 300 Hz to 3000 Hz
SLF - Super Low Frequency, 30 Hz to 300 Hz
ELF - Extremely Low Frequency, 3 Hz to 30 Hz
Power line emissions are SLF. Submarines can use ELF to transmit while
under water, but it's slow going.
I guess the radio spectrum isn't considered to go lower than 3 Hz.
-- "The polhode rolls without slipping on the herpolhode lying in the invariable plane." -- Goldstein, Classical Mechanics 2nd. ed., p207.
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