Freethought & Rationalism Archive

cricket · 10-04-2002, 02:24 AM

Now I'm reading the link someone posted above; this is a portion of Mayr's argument:

Quote:

Let us assume that there were really intelligent beings on another planet in our galaxy. A billion years ago their astronomers discovered Earth and reached the conclusion that this planet might have the proper conditions to produce intelligence. To test this, they sent signals to Earth for a billion years without ever getting an answer. Finally, in the year 1800 (of our calendar) they decided they would send signals only for another 100 years. By the year 1900, no answer had been received, so they concluded that surely there was no intelligent life on Earth.

My question: why would signals need to be directed at earth? If those beings' technological lifestyle involved radio or TV-like signals, wouldn't the signals be emitted anyway? Why must they deliberately "send signals to earth"?

Lord Asriel · 10-04-2002, 02:46 AM

Assume that there is an advanced civilisation somewhere else in our galaxy.

Assume that this civilisation has developed a technology that can examin distant stars for life-bearing planets and simultaneously detect intelligent, civilized life.

Assume the technology can do this instantly, regardless of the limitations of Relativity, and at the rate of 1 star per second.

Given that there are 100 billion stars in our galaxy (a figure from a previous post, I can't vouch for its accuracy), it would take them roughly 3180 years to search them all.

Assume the civilisation will survive long enough to complete this search.

Try to estimate the probability that, during a 3000+ year search, the one second that they are looking at our sun corresponds with a time that our civilisation is active.

Then count the number of assumptions we've just made, and estimate probabilities for them.

Then switch off your SETI screensaver, and play Counter-Strike instead

[ October 04, 2002: Message edited by: Lord Asriel ]</p>

Jamie_L · 10-04-2002, 05:11 AM

Yeah, I can believe the arguements that it's possible for all sorts of life to be out there, but that intelligent civilizations are just ships passing in the night that founder on the rocks long before encountering one another. The time scales involved in any kind of interstellar communications are so large as to make all these arguements quite plausible.

As for the probability of me vs. God, that sounds like an excellent candidate for a different thread.

Jamie

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10-04-2002, 02:46 AM	#22
Lord Asriel Regular Member Join Date: Aug 2002 Location: Essex, UK Posts: 467	Assume that there is an advanced civilisation somewhere else in our galaxy. Assume that this civilisation has developed a technology that can examin distant stars for life-bearing planets and simultaneously detect intelligent, civilized life. Assume the technology can do this instantly, regardless of the limitations of Relativity, and at the rate of 1 star per second. Given that there are 100 billion stars in our galaxy (a figure from a previous post, I can't vouch for its accuracy), it would take them roughly 3180 years to search them all. Assume the civilisation will survive long enough to complete this search. Try to estimate the probability that, during a 3000+ year search, the one second that they are looking at our sun corresponds with a time that our civilisation is active. Then count the number of assumptions we've just made, and estimate probabilities for them. Then switch off your SETI screensaver, and play Counter-Strike instead [ October 04, 2002: Message edited by: Lord Asriel ]</p>

10-04-2002, 05:11 AM	#23
Jamie_L Veteran Member Join Date: Oct 2001 Location: U.S. Posts: 2,565	Yeah, I can believe the arguements that it's possible for all sorts of life to be out there, but that intelligent civilizations are just ships passing in the night that founder on the rocks long before encountering one another. The time scales involved in any kind of interstellar communications are so large as to make all these arguements quite plausible. As for the probability of me vs. God, that sounds like an excellent candidate for a different thread. Jamie

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