Forgive me if this has been brought up, I looked back a few pages and didn't find it.

Have you read "Rare Earth"? IMO it is an absolutely fascinating theory.

I would like to have opinions from others, especially astronomers, on this.

Thanks

I read the book and thought it was pretty convincing, though I had thought along the same lines for some time.

I understand there's another book out now that debunks some of its conclusions (can't recall the title, though perhaps someone else here will be able to).

__________________
Everything I need to know I learned through Googling.

It's called Life Everywhere and is also a good read. Having read both, I still side closer to the Rare Earth train of throught, simply because in nature one expects to see a lower number of more complex life forms in any ecosystem, and there are ecosystems that could easily support less complex forms of life but not more complex ones. I found the primary attacks offered by Life Everywhere against the Rare Earth hypothesis were of an ad hominem nature, and didn't do much to suggest that intelligent life is everywhere as opposed to a rare thing.

Ironically, in the last chapter of Life Everywhere, it states various possibilities regarding what we may find or not, and their relative probability with respect to each other. While finding intelligent life under almost every rock ranked #1 (as one would expect with a book of that title [img]/phpBB/images/smiles/icon_smile.gif[/img] ) finding no intelligent life at all was ranked as more probable than intelligent life being rare. I found that interesting, as on the face of it, it went against his own hypothesis.

I don't believe that we are alone in the universe, though. Even if intelligent life is rare, on the order of a handful of intelligent species per Milky Way sized galaxy, I do not believe that it is so rare that we are the only intelligent species in the universe!

All in all, it's a very good read, and if one is going to read Rare Earth or Life Everywhere I would suggest picking up the other book and reading that, too.

_________________
If E = MC², why do I have less energy the more mass my body acquires?
That is all.

--Azpod... Formerly known as James Justin

<font size=-1>[ This Message was edited by: Azpod on 2002-05-08 14:53 ]</font>

Wasn't it Fermi who raised the question of, if life is everywhere then where is it/why aren't they [aliens] here?

__________________
Time crumbles things; everything grows old under the power of Time and is forgotten through the lapse of Time.
~Aristotle

I haven't read either book but here's my worthless 2 cents anyway. (I will definitely
put them on my books on tape to acquire list. It's the only way to drive!)

Vast distances could easily explain why we haven't seen intelligence out there.

We may be the only species on the planet that has advanced technology, but intelligence has certainly shown itself to be a most survivable trait.

I'm in the Life's Everywhere camp. It's staring us in the face but we just can't see it. See:
http://www.geocities.com/CapeCanaveral/Galaxy/7827/

Interesting site, and one that brings up good points. However, tidal friction as a means of energy production generates far less energy than solar radiation does. While environments such as exist on Europa and you theorize exist in dark nebulas are ideal for the existance of simple life forms, it would be difficult to get levels of energy required to support higher life forms. I'm not saying that it couldn't happen, but I am saying that it far more likely that intelligent life would be found on an environment such as the Earth rather than in the cores of Kupier Belt-like objects found in a dark nebula.

__________________
If E = MC², why do I have less energy the more mass my body acquires?
That is all.

--Azpod... Formerly known as James Justin

Ah, "the Fermi Question". Here's a short answer: We're monkeys. We want to go everywhere, and see everything. What's over the next hill? If we eventually discover an earthlike planet 5 or 6 light years away - impossible to get to today. We'll eventually have to go. We will go.

On the other hand, "they" (the aliens) may be out there too, and very intelligent. But maybe they're not "monkeys".

Longer answer: Timothy Ferris has another analogy. He knows lobsters are real creatures. (People claim to have seen them in restaurants). He decides to detect one, but how? He opens his front door, and sets an elegant table, with candles and champagne, and waits.... But no lobster comes up the steps for dinner. Conclusion, lobsters are exceedingly rare. (And they are, in downtown New York (except in some restaurants.) However, there are millions of lobsters in Earth's oceans.

With SETI we're looking logically too, as we should be - but maybe we're missing other subtle points.

For those who have not read Rare Earths (or read it inattentively), that book does not claim LIFE is rare. It claims that COMPLEX LIFE is rare. Its thesis: life is common in the Universe, but vast majority of that life is simple bacteria. This view is entirely consistent with John Kirien's.

Unless he thinks there are fish and lobsters inside comets?

I haven't read Rare Earth yet. Someday, but my stack of books to read is taller than me.

My guess is that life is ubiquitous. It will pop up rapidly whereever it is possible, and hold out under harsh conditions. I think it is probable that there is life beneath the surface of Mars, though I doubt the Europa fad will pay off. However, I think that intelligent life (assuming it is not overly arrogant to call ourselves "intelligent"), is likely to be somewhat rare. If I am not mistaken, this is pretty much what the authors of the book Rare Earth think, though they may think that life in general is more rare than I do.

Look at the debate between Ernst Mayr & Carl Sagan. Ernst Mayr is the dean of evolutionary biologists, and Carl Sagan was certainly the arch champion of SETI. But I think Sagan's overwhelming desire for intelligent life to be ubiquitous might have gotten the better of him. As Mayr points out, if (human-like) intelligence alone is a strong factor for natural selection to work on, then there should be more than one "intelligent" species, right here on Earth.

I think it's more appropriate to say that intelligence evolves to meet the needs. We see ourselves as "intelligent", when it might be more appropriate to see ourselves as "technological". The more we learn about intelligence in non-human animals, the more it seems that they have the intelligence they need. How does a California Sea Otter know that it can crack open crabs with rocks? It has the intelligence it needs to survive, that's how.

Trish: Wasn't it Fermi who raised the question of, if life is everywhere then where is it/why aren't they [aliens] here?

Probably was; I can't remember, but they do call it the Fermi Paradox. I worked on the NASA SETI project, back in the days when it had one. I always figured the Fermi Paradox was a pretty flimsy excuse. Not to sound too ufo-cultish, but, how do you know that aliens aren't here? The fact is that we can't easily tell that the guy in the next office isn't spying for the Russkies (as the CIA, FBI & etc. can attest), because they are "well disguised". What makes one think that a real live genuine space-alien would be any more obvious? And remember, an alien spacecraft could have come and gone, without us having a clue that it was here, right up to the close of WWII in the late 40's, when radar technology reached the point that such a spacecraft could be detected. We don't know that aliens hav never been here, and we don't know that they are not here now. We may assume both, and it may even be a good assumption, but that does not excuse the lazy practice of failing to distinguish between knowledge & assumption.

I like the idea of searching for extraterrestrial intelligence, because it returns knowledge. Each search sets limits on what is going on out there, as compared to our ability to see it. We might make assumptions about what we expect, or don't expect to see. But once we look, we know what we saw, and what we were capable of seeing, had it been there. We may never know if there is any other intelligence out there, but I can hardly imagine that looking will do any harm.

For those who haven't read the book:

The Rare Earth Hypothesis tries to explain that while LIFE may well be everywhere in the universe, complex life is extremely rare. Note the distinction between complex and intelligent. They are making a bolder claim. They support this hypothesis very well, IMO.

I have not read the other book, but wether I do or not depends on who wrote it. If it is not written by scientists I'm not interested.

I think that there probably is a lot of intelligent life out there. The universe that we can see is vast and seems to go out much, much farther than we can observe. The distances are too great for any real communication to occur (even to the nearest single stars). You can forget about intergalactic travel.

In addition, there will never be a two-way conversation because of the limitation on the speed of transmission of such communication because of the 299,792,458 meters per second (m/s) speed limit of electromagnetic radiation and much, much less for anything with mass.

However, we can all dream about space travel, even if the reality of same is non-existent.

ljbrs [img]/phpBB/images/smiles/icon_smile.gif[/img] [img]/phpBB/images/smiles/icon_confused.gif[/img] [img]/phpBB/images/smiles/icon_rolleyes.gif[/img] [img]/phpBB/images/smiles/icon_smile.gif[/img]

__________________
"There is in the universe neither center nor circumference." Giordano Bruno Born 1548. Torched 1600.

One might consider the number of arguably intelligent species alive right now on this planet. Humans, two types of chimpanzees, gorillas, orangutans, cetaceans of several types, African grey parrots, corvids, canids, and so on. Clearly, to style any of these creatures, other than ourselves, as "intelligent" is controversial, but this illustrates the point that we share a planet with numerous species which very well may be intelligent, but we can't conclusively establish whether they are or not. Where is a Turing test for dolphins? It is possible we might someday encounter a space-faring race with which we could not communicate at all? Where would they fit in our scheme? Lobsters?

I think many people fail to recognize intelligence in animals, thereby judging it to be rare when perhaps it is common. Intelligence is more than just knowing how to find food, etc. Animal intelligence is only beginning to be understood. Human brains are not that different from other primates. Marine mammals' brains are highly developed.

I once put candles out by some oatmeal to watch raccoons eat at a campground. They picked up the candles and turned them upside down to put them out. That had to be more than a learned response.

I am not familiar with the time frame of the debate you refer to. It might be that Mayr, at that time, had less evidence of intelligence in mammals than is available today. Also, I would have to guess that anything an evolutionary scientist wrote more than 5 or 10 years ago may not be valid without new evidence genetic research has provided since.

Evolution is more complex than simply the fittest surviving. Genetic research has opened huge doors into evolutionary models. Genetic change can be random, forced by climate change, forced by other environmental factors such as disease, and/or the result of being associated with some other survivable trait.

For example, a small percentage of Northern Europeans have a genetic mutation that provides resistance to HIV infection. It evolved in a population not exposed to HIV and has not appeared in Africa despite HIV being in humans there the longest.

My point is that intelligence doesn't have to be only that needed to survive. I think the evidence supports intelligence in animals on Earth as common, not rare.

We didn't think there was any life in our solar system beyond Earth. Life found at seafloor volcanic vents changed biologists view of the limits of life. Life is abundant in crustal rocks now that we're looking for it there.

Who knows what might be in Europa's oceans until we look. (Actually, I hope NASA gets with NOAA and tries listening first. NOAA has been detecting incredible sounds from unknown animals in the open ocean.) It may be that internal planetary heat can support much more than limited life. We know there are big tube worms, crabs and fish that feed off the lower life forms at ocean vents on Earth. But there may be higher life forms feeding off those organisms also. Larger animals might not be around all the time and might not have been observed yet. There isn't any biological barrier that I can think of which would prevent larger and smarter creatures from existing off of tube worms, crab meat and fish.

In medicine we say you can only diagnose what you know. It's a warning not to limit yourself to only the things you are familiar with.

I draw a sharp distinction between intelligence and technology, just to avoid the problem of defining intelligence adequately. Whales may be super intelligent for all we know, though I doubt it. But they are without technology of any kind, and always will be. Whale intelligence is incapable of being detected in a SETI type search, which can detect only technological intelligence. So if we talk about "intelligence" colonizing the galaxy, it will never be whales.

As for animal intelligence, Mayr was quite aware of all the current evidence, but sees it quite differently, as do I. Intelligence in humans is distinguishable from intelligence in other animals through the medium of symbolic abstraction. It is not apparent that any other creature on earth can handle symbolic representation & abstraction the way humans do. And if whales, for instance, could, how would we know?

This line of reasoning is demonstrated in the book The Symbolic Species: The Co-Evolution of Language and the Brain by Terrence Deacon (W.W. Norton & Co., 1997; see publisher's review).

Deacon's point is that humans, because of the way our brains are organized, by the interaction of language & evolution, are able to think in a purely abstract form that we don't see in any other animals. Now, this may be because we don't know how to look for it, or because it really is not there. One of the projects I began to work on for NASA, before SETI was axed by Congress, was an attempt to create a dictionary of Dolphin sounds (maybe somebodyelse has done thoat by now, I don't know). We were going to use signal processing methods to characterize the elements of the Dolphin calls, compared to simultaneous videotaped activity, so we could correlate what they were doing with what they were "saying". It was supposed to be a part of the SETI project dsigned to define non-human intelligence in some objectgive way, with the ultimate goal of studying communication with alien intelligence. But it perished with the rest of SETI (and it was cheap too, all we needed was an old Mac IIfx and a signal processing card). The Dolphin research would have been done at U.C. Berkeley.

But for me the main issue of the moment is the distinction between "technology" & "intelligence". Any kind of intelligence which does not communicate through technology that we can detect, is by definition "undetectable" by us. Likewise, any kind of intelligence which does not also include both the ability & desire to colonize the galaxy, will never show up in Fermi's paradox. That's why I had (and have) not much respect for the Fermi paradox idea. It leaves out too much. There may still be technology without the drive to expand & colonize, and if we don't look for it, we won't see it.


<font size=-1>[ This Message was edited by: Tim Thompson on 2002-05-09 11:12 ]</font>

I posted thoughts similar to this on the Skeptic Friends website under the poll question "Do Aliens Exist?"

It's interesting to me that the concept of picking up an alien signal seems to mirror our technology and society rather than a signal as discovered in nature. What I mean is this:
Early radio pioneers wondered about signals from Mars, and attempted to hear something. They did hear "signals" but their discoveries mirrored Lowell’s visual misinterpretations of “canals.” Later, Carl Sagan, Frank Drake, Jill Tarter and other SETI pioneers conceive of alien signals possibly being picked up at an optimum frequency based on hydrogen. This seems like a very good idea. Drake proposes his equation, another good place to start.
As the personal computer and the Internet develop, Carl Sagan writes “Contact” wherein an alien signal is, in a sense, akin to a set of instructions. Sagan and others proposed alien signals constructed like websites. The signal is a series of mathematical clues, leading to instructions. The instructions are an interactive program. The aliens are temporal creatures like us, and realize that they may not actually be around when the signal is received. Instead, they offer an interactive message. In Sagan’s book, the message leads to instructions on how to build a machine to transport us to other worlds via a wormhole. A one-way signal that opens like a website partially solves the problem of communication which "ljbrs" outlined to a degree.

Now, imagine back in 1929, Marconi or somebody gets a message that leads to advanced mathematics, that in turn leads to plastics, diodes, transistors, (remember those?) and even computer chips and a hard drive. The message tells 1929 people how to build a modern personal computer. Something they have no concept of. Then the message instructs them how to download it, and poof! a self-contain interactive program is created. Communication then proceeds between us and the alien's program, which reflects who they are (or were.)

The depressing part is, no one has thought of this until after the PC got going. (Why would they?) But they should try to think that way. That's my point. It could be that our methods of seeking ET only mirror us, that if they are really out there, we are not picking up their methods. They're too far away. Or we just are not second guessing them well enough.
Finally, there’s the whole idea that "life" is a different thing from "alien life with which we could communicate." I for one would be very excited indeed if microbes were discovered on Mars or Europa.

I think Tim Thompson's ideas are first rate. We learn by looking even if we don't find anything right away. We learn how to learn in this area. (Maybe we should design and send the interactive signal that allows alien civilizations to talk to us via a proxy computer program?) Eventually, over time, if we don’t go extinct, humans will also push out into the distant solar system and maybe far beyond.

Chip

<font size=-1>[ This Message was edited by: Chip on 2002-05-09 15:20 ]</font>

Tim Thompson last wrote' "I draw a sharp distinction between intelligence and technology, just to avoid the problem of defining intelligence adequately."

Yes, I understand your distinction and how it applies to looking for technological life beyond the reaches of our spacecraft. And, I agree, it's highly unlikely an advanced technological species exists in our solar system.

But, I disagree other species on our planet have such distinctly different brains as to not be capable of abstract thought nor symbolic language. I think technology and intelligence are not useful distinctions to guage the rareity of advanced life on our planet.

Chimpanzies and gorillas can communicate with humans in sign language and with symbolic keyboards. Chimpanzies have recently been taught to communicate with alphabet keys, actually typing out simple names like cat, no matter which order the letters are presented in. In this same research there is strong evidence for chimp vocalizations that communicate names of food types to eachother.

Parrots, with quite different brain structure, have been taught to identify color, shape, material and numbers of objects, and to use language to communicate that information to humans.

Marine mammals live in complex social groups. What alternative explanation would there be for their complex vocalizations than language? I think it's more likely we haven't deciphered the code than that the're only singing mating songs.

Many animals use tools gathering food. There are crows where I live that have their favorite parking lot. They drop filbert nuts from high up to crack them. Chimps use branches that they shake and strike the ground with to threaten other chimps.

We may be the only species on this planet with advanced technology, but we are not the only species with any technology.

I recently heard a computer scientist's response to the question of when he predicted humans and technology would become so linked as to no longer be clearly distinguishable. His answer was, "It happened when we used the first tool".

Getting back to the Rare Earth hypothesis, I think it's worth considering the logrithmic scale technology has developed on. It took millions of years from the first organisms until primates developed. If you use the model in which language and tool use created such a unique species that technology started at that time, then you presumably perceive human primates to be unique and of course, rare.

I do not think the evidence supports that model. Evolutionary science, until recent genetic research was available, looked at survivable traits as the guiding factor in the development of species. Technology, then becomes the distinguishing characteristic that defines humans.

Genetic research now presents us with the true underlying control mechanism. While survivability is still important, it is not at the controls. DNA is. To use the computer as an analogy, it would be like knowing if you typed comands on the keyboard, exactly what would occur. You tested the mechanics inside and out and you have the whole thing mapped out, except the underlying principle of digital communication. Would your word processor look the same as the computer in your car engine?

Back to the logrithmic scale of technological development, if you see DNA changes as the difference between species, rather than some unique ability or characteristic, the continuum of development seems more apparent. Humans are on the vertical curve of the scale. In a very short time, we have moved a tremendous amount higher on the vertical axis but only a short distance on the horizontal axis. That may give the false appearance that we are more different from other species than we actually are.

Advanced technology took several million years to develop. But, if humans had not evolved, it was only a matter of time before another species did. Perhaps in another million years there will be many highly technological species on the planet. Right now the evidence is not direct, and usually you wouldn't want to predict common evolution of higher technology without direct evidence. But, genetic evidence is clear. We are at the top of the technology chain, but it is a chain.

So, given the size and age of the universe, I am certain this is not the first planet in which advanced technology has evolved. I think the evidence we have indicates human technology is not unique, and, given time,we would see other technological species evolve on Earth.

I am not bothered by our lack of finding other technological lifeforms out there. On the time scale of the universe we've been looking for less than a nanosecond.

<font size=-1>[ This Message was edited by: beskeptical on 2002-05-09 16:39 ]</font>