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Ian Crawford asks: where are THEY?

By Anonymous 242 in News
Fri Jun 16, 2000 at 12:54:59 PM EST
Tags: Science (all tags)
Science

Scientific American (http://www.sciam.com) has an intriguing article, Where Are They (http://www.sciam.com/2000/0700issue/0700crawford.html), by Ian Crawford. Crawford's article explores the Fermi Paradox, If extraterrestrials are commonplace where are they? Should their presence not be obvious? The article goes on to briefly discuss three possible solutions (one of which is the Prime Directive) and how those possible solutions are not entirely satisfactory.

Crawford's piece is an interesting read that discusses some of the ideas that must considered in the hunt for evidence extraterretrial life and in exploring other planets (such as Mars).


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o Ian Crawford
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Ian Crawford asks: where are THEY? | 24 comments (24 topical, editorial, 0 hidden)
<body> ... (4.00 / 1) (#5)
by HiQ on Fri Jun 16, 2000 at 10:17:56 AM EST

HiQ voted 1 on this story.

<body> The fact that no one bothered to contact us, is a clear proof that there *is* intelligent life out there!

But seriously, I see one problem in this article:
It looks to me that astronomers never really bother to read something beyond their own field. They should have looked at evolutionairy biology:
why do people always assume that evolution is targeted towards intelligence? Intelligence is just *one* way of survival, and it has yet to be proven that it is a *good* method; we aren't here long enough to have proven that beyond doubt.

It is very well possible that the universe is full of life, none of them intelligent, but all of them survivors. The most important lesson that evolutionairy biology teaches us is that intelligence is no end-zone for evolution; there is no struggle towards intelligence.
How to make a sig
without having an idea
just made a HiQ

Intelligence (none / 0) (#10)
by Alhazred on Fri Jun 16, 2000 at 01:48:01 PM EST

However, to counter-argue there are strong reasons to believe that increasing intelligence is a strong long-term trend in evolution. Certainly organisms have been increasing in complexity steadily for almost 4 billion years on earth. Obviously bacteria did not possess the organizational complexity to develop intelligence, nor perhaps would it have done them a lot of good.

Organisms have however become steadily more complex. In addition they have tended to advance to a series of different plateaus. For the first say 2 billion years the most complex organisms were akin to bacteria, then Eukariotic organisms arose, and rapidly occupied a whole range of new ecological niches that bacteria were unsuited for.

The same thing happened again with multi-cellular life, and once more with vertebrates, and so on.

I would advance the thesis that in the long interims between new orders of life there is steady but invisible progress at lower levels, like biochemistry, reproductive strategy, etc, which eventually give life the capability to organize itself in a whole new way, which then seems to suddenly arise.

Intelligence should be seen the same way. First life had to achieve the prerequisite levels of organization. Large bodies, high metabolisms, sensitive sensory apparatus, dexterity, social organization, etc. Only then was intelligence itself of any benefit.

As many commentators have pointed out, we may well be just the outlier, the vanguard of a general advance in evolution of life on earth to a self-aware form. Despite people's doubts there are some quite obvious potential advantages to intelligence. Humans may simply be like the archeopteryx, the early predecessor or progenitor.

Or we might be a dead end. I suppose the evidence so far does tend to show that species similar to us are not to be found in every star system.
That is not dead which may eternal lie And with strange aeons death itself may die.
[ Parent ]
Re: Intelligence (none / 0) (#19)
by lucius on Sat Jun 17, 2000 at 12:14:57 PM EST

I remember reading about this in a book by Paul Davies

The thing is, complexity can evolve whether or not there is a "push" from the universe telling it to. It can arise through evolution by simply "diffusing" out. I know that is badly put, but it's hard to describe.

To use an analogy: Say I have a long box with sand up one end that I start shaking. The sand will gradually distribute itself more evenly and thinly along the box, but it will still be higher near end it started at. This will happen whether or not the box is tilted to let it happen. In fact, the only thing that will stop it happening is if the box is tilted to stop the sand moving.

So, the universe's push is analogous to the tilt (or more generally, the shape) of the box. And the amount of sand at a given point to the number of species of a given complexity. And each scenario will produce a different distribution.

The problem is, the complexity of an organism is hard to define, let alone measure (what would the units be?), and the number of organisms at a given complexity is nigh on impossible to measure for the ones where the distributions differ the most: viruses, bacteria et al.

The big issue, to my mind, is how it all got started in the first place

lucius

[ Parent ]

Re: Intelligence (none / 0) (#24)
by Alhazred on Tue Jun 20, 2000 at 12:44:49 PM EST

Essentially what your describing is 'diffusion', which can be modeled by the "drunkard's walk". A system will eventually visit every possible portion of its allowed state space. In the case of evolution, if you had infinite time then every possible evolutionary path would eventually be followed.

That doesn't materially affect the argument though, each generation of organisms must be viable, therefore evolution can only follow certain PATHS to get to certain points. In addition competition can exclude certain paths from any likelyhood of being followed. In your model that could be seen as the box being flexible and the weight of the sand changing its shape (that is to say life is part of its own environment). Thus a particular line of evolution might be viable on its own, but other better competitors might block it from happening and thus prevent life from reaching certain possible forms, even ones that might be much better evolved.

We see this a lot when we look at organisms and wonder why they don't have certain characteristics that would seem obviously advantageous to us. Why don't humans have more strength or whatnot. Those might be possible things, but either they simply haven't had time to evolve yet, or they can't evolve because getting from where we are now to there would involve intermediate steps that are poorly adapted.
That is not dead which may eternal lie And with strange aeons death itself may die.
[ Parent ]
Mmmm, extraterrestrial life....... (1.00 / 1) (#6)
by Denor on Fri Jun 16, 2000 at 11:08:43 AM EST

Denor voted 1 on this story.

Mmmm, extraterrestrial life....

-Denor


Supposing that ETs found us, they w... (none / 0) (#1)
by Neuromancer on Fri Jun 16, 2000 at 11:15:48 AM EST

Neuromancer voted 1 on this story.

Supposing that ETs found us, they would probably have the culture and technology to want to merely observe us (sorta like we do with wildlife). I mean, it's one thing if we find walking talking humanoids. If we found slime monsters that live in mercury, we would probably wouldn't start sending down space men to scare the piss out of them. However, space is a big place. If the theoretical speed limit holds true, there really isn't much way that any civilization could just be zipping around space, coming our way to give us a hihi every time they have a free afternoon. Maybe they exist and just live really far away. It seems that that is a valid assumption if you ask me.

I went through a lot of thought abo... (none / 0) (#4)
by unayok on Fri Jun 16, 2000 at 11:56:15 AM EST

Athos voted 1 on this story.

I went through a lot of thought about this at a couple of points. The conclusions I came up with are: 1. intelligent life is exceedingly rare; 2. an intelligent species has a short lifespan (from the point at which it becomes radio-capable) 2a. the period during which a species is radio-visible is even briefer (spread-spectrum radio would almost certainly be missed by current SETI efforts). 3. there is no FTL travel 4. people saying we should be able to hear (local) radio traffic of neighbouring civilizations are missing (2a) and may be misperforming the math (Earth would be undetectable to our currently deployed antennae at a distance of a couple light years at best IIRC). I doubt there's more than a couple dozen intelligent species in the Galaxy at any one time. Spread out across a vast volume. With a short lifespan. (I hope I'm wrong.)

Re: I went through a lot of thought abo... (none / 0) (#8)
by Alhazred on Fri Jun 16, 2000 at 01:22:13 PM EST

Well, your point 4 is not entirely correct, though its still a good point. The big dish at Aricebo is the most sensitive antenna we possess, at least over a wide range of wavelengths. A 1 million watt commercial TV broadcast would be visible to this antenna at a range variously estimated from 10 to 100 light years. That of course assumes someone bothers to listen. Perhaps more advanced species quickly discover that they have little to say to one another and they just don't talk.

There is also nothing to say that the urge to communicate is as strong in other species is in ours.
That is not dead which may eternal lie And with strange aeons death itself may die.
[ Parent ]
Very good article. Hopefully it'll ... (none / 0) (#7)
by excession on Fri Jun 16, 2000 at 11:56:29 AM EST

excession voted 1 on this story.

Very good article. Hopefully it'll create an interesting, although doubtless heated flamewar^Wdebate here. Th eplace needs livening up occasionally:-)

i'd give a 1 to a writeup... (none / 0) (#3)
by 31: on Fri Jun 16, 2000 at 11:59:52 AM EST

31: voted -1 on this story.

i'd give a 1 to a writeup

-Patrick

Seems to me that as how in 3.5 bill... (none / 0) (#2)
by Rand Race on Fri Jun 16, 2000 at 12:50:43 PM EST

Rand Race voted 1 on this story.

Seems to me that as how in 3.5 billion years Terra has produced exactly 1 intellegent technical species, the presence of intelegent life could be very very rare. Good atricle for discussion.
"Question with boldness even the existence of God; because if there be one, He must approve the homage of Reason rather than that of blindfolded Fear." - Thomas Jefferson

Very Interesting (none / 0) (#9)
by hrunting on Fri Jun 16, 2000 at 01:44:42 PM EST

The whole problem with the debate, though, is that it's all based on assumptions and vague calculations. There is no control group for an unbiased evaluation of what it takes to produce life, much less intelligent life. It could be that intelligent life is a freak occurrence, as witnessed by the fact that the dinosaurs lived 140 million years without a technological civilization. Or, it could be that a species living 140 million years without a technological civilization is a freak occurence that prevented the norm from happening. Even some of the tenets of evolution that the author uses to draw his final conclusion are suspect when you consider that evolution is now thought to not be as random as previously thought (ie. rather than chance mutations surviving, mutations happen with a greater profinciency towards survival). I do agree that it's foolish to think that if other civilizations exist, they're simply ignoring us because the chance that we're the only species with our tendencies seems even more remote than having no other intelligent species at all.

What the author fails to consider is that we may be looking in the wrong spot for intelligent life. Our whole assumption is that intelligent life has to be like us or its not intelligent life, that is that it's carbon-based, requires the same sort of environment considerations that we require, communicates using the same technologies that we use, etc. People have put forth the idea of silicon-based life forms, life forms that live in conditions inhospitable to us (indeed they exist on Earth), life forms that communicate using telepathy or some sort of advanced physics or other dimensions. All of this would hide these life forms from our prying eyes, and if they're operating the same way we are, we may be hidden from them as well. It may very well be like two ships passing in the night that never see each other, but may have hit each other had they been on different paths.

But as I said in the opening, there's too many what-ifs. It's like solving a+b=c for c when you know neither a nor b, nor the geometric space for the equation.

Entropy, Communications, and Evolution (none / 0) (#11)
by mcelrath on Fri Jun 16, 2000 at 04:06:17 PM EST

We're looking for radio transmissions from other species that are a) powerful and b) localized in frequency. But as we know that information density is proportional to "randomness", it is conceivable that an advanced civilization, wanting to transmit massive amounts of data would use a spread spectrum, compressed, error correcting method. This, to us, would be indistinguishable from background noise. Think about it: the first human transmissions were at a fixed frequency and amplitude modulated. This is an extremely inefficent use of the EM spectrum, and prone to noise and distortion (but very easy to pick up with a radio telescope). Now we use frequency modulation, but still in a very narrow frequency band. Spread spectrum technologies are appearing. The fact that we localize particular kinds of transmissions to narrow frequency bands is an artifact of trying to control the EM spectrum. What if other civilizations use broad spectrum, error correcting techniques, and don't try to regulate the hell out of the spectrum?

The EM spectrum is also a finite resource, one which can be used up. What happens when your information needs surpass the capacity of the EM spectrum? You wire the hell out of everything. Suddenly your civilization's EM usage drops because it's inefficent. And suddenly your civilization is undetectable by looking at radio emissions.

Lastly, try to imagine our species 1000 years from now. I'm not convinced that any civilization capable of colonizing the galaxy will choose too. In my mind, 1000 years will see us passing through a genetic modification stage, through a Borg-like stage, and on to an entirely digital stage. In all this, what will become of the hormones that make us want to hump like rabbits and make more of ourselves? Will we still have them? In the absence of sex, would we want to create new beings? In the book Eon by Greg Bear he depicts an advanced civilization (about 10000 years from now for humanity) which has a population of about 20000 beings (despite the availability of enough space to support billions), few of which even resemble humans. Birth rates decline in developed, technologically advanced civilizations. What reason do we have to believe that this trend will not continue, and the earth's populations of humans drop?

These arguments basically narrow the window of opportunity for detection to about 50-100 years, and decrease the maximum possible transmission to the largest transmitter on earth today (1 million watts?).

But then, we're all feeling in the dark, in the absence of hard data on the subject...

--Bob
1^2=1; (-1)^2=1; 1^2=(-1)^2; 1=-1; 2=0; 1=0.

Re: Entropy, Communications, and Evolution (none / 0) (#14)
by synaptik on Fri Jun 16, 2000 at 05:05:33 PM EST

How do you wire between planets?

--synaptik
warning C4717: 'WORLD3D::operator=' : recursive on all control paths, function will cause runtime stack overflow
[ Parent ]

Re: Entropy, Communications, and Evolution (none / 0) (#16)
by YellowBook on Fri Jun 16, 2000 at 05:46:15 PM EST

How do you wire between planets?

Message lasers.



[ Parent ]
DOCUMENT CONTAINED NO DATA (none / 0) (#12)
by 3than on Fri Jun 16, 2000 at 04:30:02 PM EST

Gotta say, it's tough to make any conclusions at all. We're acting in what's more or less a total vacuum-there's a huge amount of speculation, and very little information. But it seems to me that most of our assumptions are pretty wrong. Like:
1. It's great to be intelligent. Why wouldn't every living thing want to be intelligent?
2. It's possible for us to communicate. Serial communication based on a series of symbols, visual or sonic, is the natural way to communicate, Right?
3. We'd know it if we saw it.
I just don't know. It seems to me that 'life' as we conceive it may be of fairly little value to an advanced society. We seem to have enough trouble with it....what if an information society went into a long-term phase, where they only exist as data encoded into DNA with specialized delivery systems? Isn't a virus the ultimate in indestructible, encrypted data? I'm a fan of the extraterrestrial virus idea, obviously, since it seems so apt-virii are arguably the best form of interstellar information exchange.
Well, whatever the speculation might be, it seems that we're a long way(in our terms)away from any ET civilization. If we want to find other civilizations in space, we'd better put them there. I'm with Crawford-let's go to Mars. It may be a waste, or a total boon, but it's the next place that man the explorer needs to go. Let's concentrate on the alien nature of our civilization-it seems like, long-term, we can make ourselves the everything that we want them to be.

FTL and Radio (none / 0) (#13)
by tommasz on Fri Jun 16, 2000 at 04:31:46 PM EST

As much as I hate to admit it, perhaps Faster Than Light travel really is impossible (no artificial wormhole shortcuts either). That would certainly explain why no one has come to visit, it just takes too long. Of course, we just might not be interesting enough for the "neighbors" to visit :) That aside, they'd know were we are, culture-wise, by having detected our transmissions (provided they could decode them, etc.) that we've been pumping out into the cosmos. So where are their transmissions? Electromagnetic radiation is all over the universe and a handy way of communicating over distances without infrastructure between sender and receiver(s). It's hard to imagine that we're the only ones using it. Is seti@Home just not sophisticated enough to detect what someone's sending us? Are we being "quarantined" for our own good? I hope I live long enough to find out.

Good Books (none / 0) (#15)
by Anonymous Hero on Fri Jun 16, 2000 at 05:29:57 PM EST

There are a number of very interesting and very sophisticated books on the subject of extraterrestrial life. Two of the best I have come across are Barrow and Tipler's "The Anthropic Cosmological Principle" and Tipler's "The Physics of Immortality". Both are primarily concerned with cosmology (and get very "far out"), but spend a good amount of time discussing extraterrestrial life and interstellar colonization and both have a good overview of the history of thought on the subject.

Re: Good Books (none / 0) (#17)
by Anonymous Hero on Fri Jun 16, 2000 at 07:14:57 PM EST

The coollest argument in the Anthropic Cosmological Principle is the one that shows, by purely probabilistic arguments about the likelihood of life evolving, that we are doomed to extinction any day now. The basic idea is this: Suppose (a reasonable suggestion) that in a solar system's lifetime that there is only a certain window of opportunity in which life can arise (maybe several billion years before the star goes nova or red giant - say this time T)

Suppose also that life is in fact extremely unlikely and that it takes time t (much bigger than T) for it to 'spontaneously' arise out of a primordial soup (again reasonable for reasons given in SciAm - we don't see much life out there).

Then we have a joint probability for t and T. We know the value of t (3.5 billion years) but this has been sampled from a special supspace (t<T) so we must use conditional probabilities. It's tricky to get good figures but one thing that can be shown (because the mean of t is much greater than the mean of T yet we are conditioning on t<T) is that t is likely to be quite high compared to T (though not greater than T of course). If life is really unlikely (and you must read the book to see the details) than T-t might be expected to be of the order of only a few tens of thousands of years.

Think about it - or even better read the book. It's a pretty good argument from a mathematical perspective.
--
http://www.sigfpe.com

[ Parent ]
What's wrong with the obvious answer? (none / 0) (#18)
by Wolfkin on Sat Jun 17, 2000 at 07:34:27 AM EST

Why is it that so many people seem to take it as a given that intelligent extraterrestrial life must exist, and then try to explain away the evidence? It seems fairly clear that intelligence (and possibly life in general) is not at all common in the universe.

Randall.

Re: What's wrong with the obvious answer? (none / 0) (#22)
by tommasz on Sat Jun 17, 2000 at 10:38:18 PM EST

Why is that the obvious answer? Wasn't it Carl Sagan who said "Lack of evidence does not imply evidence of lack"? There's plenty of evidence the universe likes to repeat patterns, why not us?

[ Parent ]
Re: What's wrong with the obvious answer? (none / 0) (#23)
by Anonymous Hero on Sun Jun 18, 2000 at 03:56:21 AM EST

>Why is it that so many people seem to take it as a given >that intelligent extraterrestrial life must exist, and >then try to explain away the evidence? It seems fairly >clear that intelligence (and possibly life in general) >is not at all common in the universe.

Going deep into the realm of speculation, could it be possible for intelligence to exist without life (our definition at least)

That the conditions for life abound(sp?) in the galaxy i'll buy it. That life MUST lead to intelligence, that i'll doubt. Has anyone ever considered the alternative (that intelligence NOT NECESARILY means life)
But anyway, we are talking about BILLIONS of years for crying out loud! Anything could have happened. Maybe dinosaurs evolved into intelligent beings, screwed up, and destroyed almost all the traces of life on earth (in such case we must reconsider the definition of "intelligent beings"). More than a hundred millions years after that, another species with nuclear weapons wonders how could the dinosaurs become extinct.

Just wondering of course

[ Parent ]
Broadband... (none / 0) (#20)
by w3woody on Sat Jun 17, 2000 at 02:57:24 PM EST

I just wonder if the SETI folks would be able to distinguish an error-correcting broadband transmission from background radiation. I doubt it. Which means that in the equation of computing how many ETs are out there, we also need to factor in the percentage of ETs we are able to detect with our current technology. And I suspect, giving how long it took us to go from AM to Broadband (about half a century), that we could believe we're quite alone out there when there are literally thousands of advanced civilizations out there.

My Theory (none / 0) (#21)
by Anonymous Hero on Sat Jun 17, 2000 at 07:30:44 PM EST

Every technological civilization naturally develops an interest in particle physics. They build more and more energetic experiments, culminating in a machine like Brookhaven's RHIC, and inadventantly convert their planets to strange matter before migrating to space.

Ian Crawford asks: where are THEY? | 24 comments (24 topical, 0 editorial, 0 hidden)
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