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- From: garry@sr.hp.com (Garry Bryan)
- Newsgroups: alt.paranet.ufo
- Subject: Re: Radiowaves?
- Date: 18 Jun 1996 23:45:34 GMT
- Organization: Hewlett Packard Sonoma County
- Lines: 47
- Message-ID: <4q7f2u$76t@canyon.sr.hp.com>
- References: <700.6741T278T966@gaia.swipnet.se> <4q3tve$m5r@canyon.sr.hp.com> <2304.6743T957T712@gaia.swipnet.se>
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-
- Tommy ClarΘn (mg19768@gaia.swipnet.se) wrote:
-
- : >Here's a repost of one reason why we won't hear them. . .
-
-
- : >The formula for EMF propagation is P(ower detected)*4Pi(D)istance)^2 =
- : >ST(rength of source signal.
- : >Using 3.0E8 mps as the distance light/EMF travels in a second you can get a
- : >distance of 9.23E16 meters at 10LY. This is relatively close.From a
- : >conversation with Dr. Beck of the PHOENIX project he told me that they
- : >currently can detect signals on the level of 1.3E-27 watts. Plugging in the
- : >numbers you get a source strength of 139,099.068.68 Watts of power at the
- : >source. 139 Megawatts is a LOT of power. If you use a typical 20dB gain
- : >antenna you could narrow the beam and lessen the power to 1.39 Mega watts.
- : >And SETI is looking at stars in
- : >50LY range, again from a talk with Dr. Beck. So the power needed is 69.5 Mw
- : >for use to detect it. We have no need for such signal strength, I don't even
- : >think HAARPo will use that much power. Why would we suspect an ET race to be
- : >wasting such power on local communications? It just doesn't make any sense to
- : >expect these ET's to be doing things differently than us. After all, SETI
- : >assumes that they will use radio waves for communication. . .
-
- : >Garry (%^{>
-
- : I read somewhere that because our radiosignals have reach 40-50 LY out in
- : space, the earth would shine as a small sun in a radiotelescope, so I
- : thought that radiowaves just goes on for ever out there.
-
- : But this is obviously not the case.
- : Thank's, I appreciate your good answer.
-
- : But this generates a new question. How did they find us?
-
- The speculative answer would be the same way we decide which stars to listen to
- (unsuccessfully) in the SETI searches. We target stars in the neighborhood that
- are of a similar luminosity or age. So far we have detected planets around other
- suns without a lot of difficulty. Now the big if is IF one had FTL or near light
- speed transport one could get within a few lightyears of some candidates and
- then listen for EMF. Better yet, just go to the stars that have detected planets
- and look for planets in the region where liquid water is possible. Oh, and as
- far as our planet "shining" with EMF we are too close to another broadband EMF
- radiator, the Sun, to be easily detected. Remember SETI is looking for
- intentionally created signals. We don't send EMF messages to the stars so why
- hope an ETI would do so. . .
-
- Garry (%^{>
-
-