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From: desj@brahms.BERKELEY.EDU (David DesJardins)
Newsgroups: net.columbia
Subject: Re: Shuttle sonic booms
Message-ID: <11242@ucbvax.BERKELEY.EDU>
Date: Sun, 15-Dec-85 06:53:44 EST
Article-I.D.: ucbvax.11242
Posted: Sun Dec 15 06:53:44 1985
Date-Received: Tue, 17-Dec-85 03:47:57 EST
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Reply-To: desj@brahms.UUCP (David DesJardins)
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In article <815@umd5.UUCP> don@umd5.UUCP writes:
>
>                                      ... one can't HEAR a sonic boom
>because by the very nature of the phenomena it is SUPERSONIC.
>
>One does sense the window-rattling abrupt changes in air pressure, however.
>If I'm not mistaken, the air pressure states go: ambient-low press.-ambient
>as the shockwave "cones" pass by.
>
   I don't know what you think sound is, other than a variation in air
   pressure.  The fact is that a sonic boom is produced by any object
   traveling at (or near) the speed of sound.  It is (loosely speaking)
   the superposition of the sounds emitted by the object at different
   times, arriving at the observer at the same time.  (Note that I am
   not claiming that this is completely accurate, but it is sufficiently
   so for this discussion.)
      Furthermore, in the absence of temperature changes pressure throughout
   a volume must be conserved, and so it is not possible for pressure to dip
   below ambient without also rising above ambient.
      Finally, I guarantee that I, and many other people, have HEARD sonic
   booms.

      -- David desJardins