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A problem with SETI....


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I believe wholeheartedly that we are not, in fact, alone in the universe. I think there's probably life all over the place, and probably plenty of intelligent life too. So why hasn't SETI found even a hint of it (Wow! signal notwithstanding)? Well, I thought that maybe, not everyone uses radio waves. After all, many stars with planets are turning out to be red dwarfs. Red dwarfs often give rise to flares, which can be quite loud in the radio spectrum. Having radio recievers kicking about at this time could be impractical and frustrating. So I thought 'how else might an alien civilisation communicate with itself around its own planet and solar system?' Enter

http://gsfctechnology.gsfc.nasa.gov/TechSheets

/XRAY_Goddard_Final.pdf

which is a chap at NASA who's developing an x-ray communication system which he reckons will be just peachy for interplanetary distances.

So my question is:

"Is the SETI looking in the right way, and if not, how should we be looking?"

Go!

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Red Dwarf systems aren't thought to be particularly good for habitatability.

And it's not especially surprising that SETI has yet to find any evidence of life beyond the Earth, or any radio signals in that time. It's been around for about 50 years, yet has not been able to search actively for anywhere near that. I think only about 750 stars have been observed by SETI projects and obviously not all the time.

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I too think that unfortunately they're wasting their time.

We are rapidly changing over from radio to cable communications, and so most of the radio signals we produce are pretty low level.

You've got to catch the ET civilisation in exactly the period in its development where it's generating enough radio output to be detected over such vast distances...and this is assuming that all sentient creatures willl develop technology at all....just because we did doesn't mean that it's the rule...we only have one example to draw any conclusions from!

Rob

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We are rapidly changing over from radio to cable communications, and so most of the radio signals we produce are pretty low level.

Even when a signal is very strong, the receiver must be relatively close, or else that signal will be utterly lost amongst the natural background noise, as per the inverse-quare law.

You've got to catch the ET civilisation in exactly the period in its development where it's generating enough radio output to be detected over such vast distances...

Assuming there are and have been many intelligent species beyond the Earth (and yes, it's a big assumption, but nevertheless...) they will likely be spread over distances and therefore time, so I don't think that's as big an issue as you may believe.

The problem is, as stated above, the inverse-square law, which essentially says that unless the source is very nearby, any signal radiating from it will soon be lost, no matter how sensitive the receiving equipment being used.

People often repeat the old myth about little green men being appalled by Hitler opening the Olympic Games, but that scenario is only possible if they are close enough to be able to differentiate the signal from the all-pervasive Cosmic static. We're only talking about 50 LY or so. If they were that close, you'd think we'd have noticed by now.

...and this is assuming that all sentient creatures willl develop technology at all....just because we did doesn't mean that it's the rule...we only have one example to draw any conclusions from!

That's true. But the odds do seem to favour the existence of a fairly large number of intelligent ET species, and that would suggest that a few of them will probably like to tinker with gadgets.

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See a nice (2 megabyte) picture at the link below.

http://jackadam.net/misc/radio_broadcasts/radio_broadcasts.jpg

You can see just how far our man-made signals have propagated in the last 200 years.

And bear in mind too that beyond a few dozen LY, those signals become undetectable because their intensity levels falls below that of the background noise.

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Assuming there are and have been many intelligent species beyond the Earth (and yes, it's a big assumption, but nevertheless...) they will likely be spread over distances and therefore time, so I don't think that's as big an issue as you may believe.

To create something like us, a generation of stars had to be born, die, and then the resulting debris form intp planetary systems and then form life, followed by life that was sentient. I suspect that it's not spread ovetr a truly huge amount of time. Guessing of course, as we all are :-)

But the odds do seem to favour the existence of a fairly large number of intelligent ET species, and that would suggest that a few of them will probably like to tinker with gadgets.

The odds are actually hugely stacked against our existence, but I imagine that in the highly unlikely event that sentient species are common, it's likely thay would be quite fond of gadgets too!

I personally think that life is going to be widespread, and will achieve sentience if conditions allow, but these conditions may well prove to be very rare.

Rob

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See a nice (2 megabyte) picture at the link below.

http://jackadam.net/misc/radio_broadcasts/radio_broadcasts.jpg

You can see just how far our man-made signals have propagated in the last 200 years.

And bear in mind too that beyond a few dozen LY, those signals become undetectable because their intensity levels falls below that of the background noise.

200 years? I do not understand where they get 200 years from? First radio demonstration was in 1893 by Tesla and was short range. The first radio broadcast was in 1906 in Massachussetts. All early radio was in the long, medium and short wave bands wave as they are reflected off the ionosphere and the ground / sea, so the most of the signals did not leave the Earths atmosphere. In the late 1920's they started to develop the technology for VHF radio, and these are the first radio broadcasts to not be reflected by the ionosphere, also they were of low power, a few tens off Watts. The BBC were the first to broadcast TV at a high power in the late 1930's.

Up unto 1919, radio was mainly broadcast as Morse and by means of spark transmitters, then transmission by AM began with valve technology to amplify the transmitted and received signals.

So really we have only been broadcasting radio inadvertantly into space for around 80 years.

Also anyone listening to radio broadcasts from Earth in space would have a job to pick up individual signals, as they are re-used all around the globe, and would become a jumble of languages and music, with no single station standing out above the other. To add a further complication, each broadcast arriving at the alien receiver, would arrive in different phases, and as such, reduce or increase the signal strength. Still this effect would average its self out, with possibly over a hundred stations all broadcasting on the same frequency :)

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To create something like us, a generation of stars had to be born, die, and then the resulting debris form intp planetary systems and then form life, followed by life that was sentient. I suspect that it's not spread ovetr a truly huge amount of time. Guessing of course, as we all are :-)

Stars and planets last a long time, by the standards of life.

The odds are actually hugely stacked against our existence...I personally think that life is going to be widespread, and will achieve sentience if conditions allow, but these conditions may well prove to be very rare.

It's a numbers game. The number of galaxies; the number of stars in those galaxies; the percentage of stars that have planets; the percentage of planets in orbits suitable for Life As We Know It; etc, etc. It's a big number.

Still, somebody has to be the first.

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For something like us to evolve, a generation of stars had to form, then eventually burn out, collapse or explode, and then the resulting debris form into planetary systems and then form life, followed by life that was sentient. ...

Fixed your typos. :)

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...and this is assuming that all sentient creatures willl develop technology at all....just because we did doesn't mean that it's the rule...we only have one example to draw any conclusions from!

It's merely a constraint on that particular search.

The operational definition currently used by SETI of "intelligence life" is whether or not something can make a radio transmitter. Because, from the point of view of SETI, if something can build and use a radio transmitter then they have a chance of finding them.

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It's merely a constraint on that particular search.

The operational definition currently used by SETI of "intelligence life" is whether or not something can make a radio transmitter. Because, from the point of view of SETI, if something can build and use a radio transmitter then they have a chance of finding them.

Whilst I applaud the intentions behind the search I think this is a fairly hopeful criteria. As has been pointed out, the human use of radio waves as a medium of communication is already heading towards obsolescence and that great media junkyard to join cave paintings, smoke signals and the electric telegraph ('the first internet'! :)). Give it another 20 years and you have, what? A century's worth of signals.

Given how contingent the selection of materials, wavelengths and forms of broadcast have been the chances of an ETI using them in same way as us, to a sufficient degree, for a long enough time, in close enough proximity to us (etc) is pretty remote. Being an optimist, I'm sure that at some point we will develop a communications system (neutrino carrier nano-pigeons?) which is of use over the vastness of space and which might be usefully perceivable any number of LYs away.

Of course, that is dependent upon ETIs also having developed neutrino carrier nano-pigeons otherwise they might fly past the ETIs psychic strangeness amplifiers and quark receivers undetected... :)

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Rob, I know what you mean when you say that the odds are stacked against life, but there may be other factors at play which might, in fact, make it probable. We need to know what to factor in when calculating the probabilities.

Evolution by natural selection, in which I'm almost as firm a believer as Dawkins, seems to drive matter into forming self reproducing automata. (like us!) Or, to look at it another way, stopping life seems to be nigh on impossible. It is easy to do away with any one species or group of species but to do away with life is not something nature has managed to do since the dawn of life on earth. And try keeping hospitals sterile!

The distribution of matter and energy (the stuff of life) is very consistent throughout the observable universe. Maybe we are wrong to concentrate on the forces adversarial to life. I wonder if there is a deeper set of forces driving life on into existence. I'm really just thinking of statistical forces at small scales, nothing mystic at a all. I'm always mindful of the Copernican principle stating that, if there seems to be something special about your situation, then your underlying theories are probably wrong. I suspect that there will emerge an explanation of the presence of life that, like Darwinism, makes the seemingly improbable into the probable.

Lee Smolin took this approach in order to tackle the various fundamental problems in cosmology - in which fine tuning of the numbers seems to be necessary for us to exist. He produced an hypothesis in which universes which are good breeders reproduce themselves via star formation - of which we seem to be a by-product.

Olly

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Whilst I applaud the intentions behind the search I think this is a fairly hopeful criteria. As has been pointed out, the human use of radio waves as a medium of communication is already heading towards obsolescence and that great media junkyard to join cave paintings, smoke signals and the electric telegraph ('the first internet'! :)). Give it another 20 years and you have, what? A century's worth of signals.

Given how contingent the selection of materials, wavelengths and forms of broadcast have been the chances of an ETI using them in same way as us, to a sufficient degree, for a long enough time, in close enough proximity to us (etc) is pretty remote. Being an optimist, I'm sure that at some point we will develop a communications system (neutrino carrier nano-pigeons?) which is of use over the vastness of space and which might be usefully perceivable any number of LYs away.

Of course, that is dependent upon ETIs also having developed neutrino carrier nano-pigeons otherwise they might fly past the ETIs psychic strangeness amplifiers and quark receivers undetected... :)

True....it is time we all upgraded our carrier pigeons.

I suppose as we develop, there will be other techniques developed to attempt SETI detections or the current experiments will be refined - the Allen Telescope Array was somewhat meant to do this. I think there are already other projects looking to detect high-power laser beams near stars - still a futile endeavour perhaps, but then money is wasted on far less worthwhile things.

The ATA cost about £20million to build and needs about £1.5million per year to run, with a 20 year expected lifespan (compare that to the £50million that Prince William's wedding cost or the $800million a Presidential candidate receives in donations).

Also remember that several of the SETI experiments have produced new techniques for data gathering, signal analysis, computational algorithms that I would assume have other uses.

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True....it is time we all upgraded our carrier pigeons.

I suppose as we develop, there will be other techniques developed to attempt SETI detections or the current experiments will be refined - the Allen Telescope Array was somewhat meant to do this. I think there are already other projects looking to detect high-power laser beams near stars - still a futile endeavour perhaps, but then money is wasted on far less worthwhile things.

The ATA cost about £20million to build and needs about £1.5million per year to run, with a 20 year expected lifespan (compare that to the £50million that Prince William's wedding cost or the $800million a Presidential candidate receives in donations).

Also remember that several of the SETI experiments have produced new techniques for data gathering, signal analysis, computational algorithms that I would assume have other uses.

Don't get me wrong, I fully agree with SETI's ongoing efforts for all the reasons you lay out but I, sadly, don't expect them to bear fruit in my lifetime. But, as ever, fingers crossed!

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Hi Olly....I don't believe that the odds are stacked against life itself, in fact I wouldn't be at all surprised if it turns out that self replication etc is a fundamental property of matter.

What I suspect may be rare is for self aware technologically capable life to arise. Of course, the universe (just this one!) is vast and so there are lots of chances, but it also means that it might not be just around the corner so to speak, and it also needs to be at roughly the same stage in an almost parallel development to us in order for SETI's radio search to find it.

This I find extremely unlikely.

Of course, this entire thread is pure conjecture....until we either find that life has been fruitful, and multiplied, or it hasn't, all we have are opinions based on what we know about life in our own particular cradle.

Cheers

Rob

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Pure conjecture indeed, but perhaps one of the most delicious of questions! Personally my instinct tells me that the universe will be teeming with life. Dwelling on all the objections seems to me to be rooted in preconceptions based on too closed an attitude to how it might work. To get earth-like life you need an earth-like environment, and that isn't likely at all. But what else might be possible?

Olly

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if you take the earth as a model, I think that life may be common but intelligent life rare.

Life started on the earth very quickly, probably 1/2 a billion years after it had formed. This is quiet amazing considering the environment - very hot from formation, lots of radionucleides abounding, subject to massive asteroid bombardment, high UV radiation - every thing against it really.

However it then stayed much as it was for the next 2-3 billion years. The next big thing was multicellular life - somewhere around 600-700 million years ago.

After that we see the rise and fall of lots of creatures. None of them as far as we know became intelligent. Trilobites, all sorts of dinosaurs, other things came and went, none of them became intelligent. This happened over 500 million years - so lots of attempts.

Humans appeared within the last 2 million years.

So it would seem life gets started pretty much come what may on something like the earth. Getting to the next stage takes quite a while and a happy accident probably, and intelligence takes another time and probably another happy accident.

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So it would seem life gets started pretty much come what may on something like the earth. Getting to the next stage takes quite a while and a happy accident probably, and intelligence takes another time and probably another happy accident.
Yes - Basic life seems almost inevitable. Advanced life does seem to require a lot more "fine tuning". A planet with axis (seasonal) stability etc. etc. Also the high risk of "extinctions" - Some global, some rather more "personal"? The Malaria parasite almost "did for" most of homo sapiens? - Those it didn't kill, almost ended up a (big) Cat Food. :)
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It's a numbers game. The number of galaxies; the number of stars in those galaxies; the percentage of stars that have planets; the percentage of planets in orbits suitable for Life As We Know It; etc, etc. It's a big number.

Aye, and it's known as the Drake Equation and there are 7 factors. Interestingly, the people as SETI recently revised their own estimates of the factors using the latest Kerpler data and they "reckon" they could detect a signal within the next 15 years. Obviously it can only be an estimate, but I *do* think that they at least factored in the fore-mentioned problems associated with the inverse square law, noise etc etc.

if you take the earth as a model, I think that life may be common but intelligent life rare.

Well, it's always going to be controversial but apparently Drake himself used a value of 0.01 (1%) for this particular factor (fi = the fraction of planets with life that actually go on to develop intelligent life).

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