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SETI - unjustified leap in reasoning?

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#26 dickbill

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Posted 11 February 2013 - 03:01 PM

"It just means we still do not have the capability of making a reasonable determination which in no way can influence the likelihood"

Even that is not obvious.

#27 Qwickdraw

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Posted 11 February 2013 - 04:16 PM

"It just means we still do not have the capability of making a reasonable determination which in no way can influence the likelihood"

Even that is not obvious.


As in the double slit experiment?

#28 dickbill

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Posted 11 February 2013 - 05:49 PM

Hmm, i wouldn't say 'Life' is a quantum state, with an exclusion principle, which would forbid another instance simultaneously, or an indetermination principle which would forbid us to observe another instance without interacting and possibly destroying it.
But some probably do. A theory exists that explains the basis of consciousness resides in the quantum properties of certain elements in the brain (microtubules to be precise, http://www.quantumco...usevents.html).

I am more puzzled by the so-called anthropic coincidences which are more in line with the information theory. Leon Brillouin, an expert in the field, said:"...If a situation is rare, it contains information". It seems that's us. I find the anthropic coincidences very suspicious, some of them more or less so, but there is one that is so un-necessary a-priory (like in a bayesian prior that is non zero when it should be zero) that it has ruined my faith in the current interpretation of Life.

#29 llanitedave

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Posted 13 February 2013 - 10:13 AM

The thing is, what SETI is looking for is not just intelligence, but a familiar technology. That's far more difficult than either "mere" life or "mere" intelligence. It assumes a home planet that is not just Earth-like, but Earth-twin.

There are many scenarios that would allow life on a planet to flourish, and maybe --maybe even intelligent life to evolve, without that life ever developing the kind of technology that would allow them to leave their planet or even easily observe anything beyond it.

If the Earth possessed just a small percentage of water more than it does now, for example, it would be almost completely inundated, with no exposed continental masses. Intelligent creatures there would be aquatic. It's hard to imagine a way that they could use fire-based technology, and without fire as a stepping-stone, any other high-energy power source that would give them access to the universe beyond their atmosphere is difficult to say the least.

A planet somewhat more massive than the Earth, on the other hand, might have a much thicker and less transparent atmosphere on the surface. Stars may be more difficult to see and study, and the entire tradition of their detailed exploration may be hard to establish.

The evolutionary chances and forks that led to the appearance of a technological intelligence on Earth were unique, and probably very unlikely. Even if life is fairly common out there, there would not be many planets, even Earthlike ones, that would develop such a species. And "Earthlike" is so broad a term, that the chances of any life form at any detectable distance being familiar to us seem vanishingly small.

#30 dickbill

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Posted 13 February 2013 - 12:09 PM

If the Earth possessed just a small percentage of water more than it does now, for example, it would be almost completely inundated, with no exposed continental masses. Intelligent creatures there would be aquatic. It's hard to imagine a way that they could use fire-based technology, and without fire as a stepping-stone...


It never occured to me, but that's right!
But anyways, SETI is not so hot anymore. I don't know how it got funded. Did I open a thread once, called 'Kepler killed SETI'? i don't remember but that's the idea. A giant telescope in space actively looking for signs of life is more usefull than a network of antennas passively scanning for extraterrestrial TV broadcastings.

#31 Jason H.

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Posted 13 February 2013 - 01:06 PM

...But anyways, SETI is not so hot anymore. I don't know how it got funded. Did I open a thread once, called 'Kepler killed SETI'? i don't remember but that's the idea. A giant telescope in space actively looking for signs of life is more usefull than a network of antennas passively scanning for extraterrestrial TV broadcastings.


SETI Institute scientists are on the Kepler team (so Kepler didn't kill SETI, Kepler IS SETI.) Indeed a scientist, Laurance Doyle, was the lead on the paper for the first-detected Saturn-class planet orbiting around a binary star system:

NASA's Kepler Mission Discovers a World Orbiting Two Stars
http://www.nasa.gov/...kepler-16b.html

Kepler-16: A Transiting Circumbinary Planet
http://arxiv.org/abs/1109.3432

and also was on this paper
Kepler 16: A System of Potential Interest to Astrobiologists
http://arxiv.org/abs/1111.0002

and a number of other papers.

Note that his employer as stated in the first paper is "Carl Sagan Center for the Study of Life in the Universe, SETI Institute, 189 Bernardo Avenue, Mountain View", and in the second paper
"Carl Sagan Center, SETI Institute, 189 Bernardo Avenue CA 94043"

(disclosure: I just started moderating a forum of Dr. Doyle's.)

Also, what started this thread is the fact that the SETI Institute (and others) can finally target specific real targets because of Kepler; Kepler permits SETI, doesn't kill it. Kepler also shows that SETI can be done on very nearby planets, by proving they are ubiquitous.

Also, SETI is not a monolithic entity, there are others beside the SETI Institute who are conducting their own searches in other parts of the electromagnetic spectrum that differ from those searched by The SETI Institute (i.e. not in 'the waterhole', but in lower frequencies, much higher frequencies and even the optical and IR.)

SETI does not look for extraterrestrial TV broadcasts, as it is not sensitive enough to detect such signals.

And regarding searching passively in the microwave band, there are many good reasons to search there (that I don't think are necessary to elaborate on.) There are many good reasons to search the rest of the electromagnetic spectrum too. The search domains are not mutually exclusive, and there is no evidence at all that one method would or should be preferred (and if one thinks that searching for 60 years is a reason why radio shouldn't be searched, one really doesn't understand the search space and what has been done previously.)

Of course a super-massive space telescope would be a desirable next step, to image exoplanet's directly and detect their simple biology, but that doesn't seem likely in the near future.

Regarding "I don't know how it got funded...", please consider taking the time to look into this. I fund it, and like-minded people fund it, and an incredibly small fraction of 1 penny/cent of your personal taxes may have funded one kind of SETI back in the early 1990's.

All SETI radio telescopes conduct radio-astronomy science simultaneously. Nobody's money is wasted. Indeed, one of the direct spin-offs of creating the Allen Array in California will be applying the same dish combining solutions to the Square Kilometer Array (the same scientists and engineers are involved.)

My personal hope is somebody comes up with a different solution to the budget problems of creating a giant space telescope; I've personally been thinking a lot about polarized light, both light that's polarized by extraterrestrial oceans, but also as a means of communication (easier to differentiate from other light sources?) I guess that's for another thread?

Regards, Jason W. Higley

#32 llanitedave

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Posted 13 February 2013 - 09:26 PM

+1 Jason. Whatever you think of the odds of success for SETI, it's worth it, because the data collected is so useful across such a broad spectrum of studies.

The purpose of science is to drive knowledge forward, and SETI is doing just that -- at a pretty slim expenditure too.

#33 SteveMushynsky

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Posted 15 March 2013 - 05:11 PM

What would the margin of error be for a null result among a statistical sample of 86 among a near-infinite number of star systems?

#34 Qwickdraw

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Posted 16 March 2013 - 10:31 AM

I also have to wonder if the lack of contact can point to the conclusion that intellectually superior races by misfortune stumble upon some unknown force of nature during physics experiments that systematically eliminates whole planets or even solar systems during the course of discovery. We don't know what we don't know.

#35 Jason H.

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Posted 16 March 2013 - 09:28 PM

"The existence of extraterrestrials is not an issue that can be determined on the basis of theory, no matter how compelling the arguments. SETI by definition is an experimental science." - Frank Drake

#36 Ira

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Posted 17 March 2013 - 08:57 PM

I also have to wonder if the lack of contact can point to the conclusion that intellectually superior races by misfortune stumble upon some unknown force of nature during physics experiments that systematically eliminates whole planets or even solar systems during the course of discovery. We don't know what we don't know.


Death Stars rule! :dabomb:

/Ira

#37 llanitedave

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Posted 18 March 2013 - 02:32 PM

We've already seen arguments that we should let robots do just about everything that might be dangerous, difficult, or inconvenient for humans. I can see the possibility that we just might invent ourselves right out of biological relevance.

Maybe the robots will help us to our extinction out of pure mercy. That may be more likely or sooner than the asteroid impact.






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