So....where are they? (Fermi Paradox)

[Mangetout]

[QUOTE]
*Originally posted by Gary Kumquat *
**

*Originally posted by Mangetout *
**blah blahQUOTE]

Very true. We’ll only find out if we try though. **

Sure, I’m not suggesting that we stop trying, quite the opposite in fact, I think if we don’t try very hard indeed, then we stand no chance whatever.

[hardcore]

SPOOFE:

::sigh:: You’re missing my point. The simple fact that we haven’t seen any ET’s would discount this reasoning… or would indicate that the ET’s are purposefully trying (and succeeding) to hide themselves from us.

sigh right back atcha :rolleyes: Just because I disagree with your reasoning doesn’t mean I am missing a point, any more than you are missing mine.

I agree that the fact we haven’t seen any ETs probably means there is no Galactic Empire. That’s kinda been my point from the beginning. I discount the possibility of an “invisible” empire, because I don’t think it is likely. Even an unseen empire would need to communicate with one another, and we have yet to intercept anything that indicates intelligence. And this does not address the question of why they would have left our system intact. Plus, the whole “invisible” idea leaves the realm of the logical and enters the highly speculative.

You appear to have fallen prey to what I like to call “Star Trek syndrome”… assuming that alien cultures are even remotely recognizable by our standards, and assuming that we’re important/great enough to be able to detect them. There is no reason why we should assume this.

If anyone is using “Star Trek syndrome” it is you with this Cosmic Quarantine hypothesis. I am simply trying to use Occam’s Razor. The reason we do not detect ET and his galactic empire is because they do not exist.

Additionally, even if we assume that the ET’s are billions of years more advanced than we are, that is no reason to assume that they would have come across us by now. As I’ve said, barring some form of FTL travel, it could take many millenia to starhop just a small distance across the galaxy.

As I have previously indicated, it only takes 5 million years to span the entire 100,000 light-year distance of our galaxy, travelling at 10% the speed of light with a 10 light-year spacing between colonies and a 400 year latency period between expeditions. If ET only had a 0.1% headstart on us, he would have completely colonized the galaxy 5 million years ago while we were still chimps.

There’s that “Star Trek syndrome” again… you’re assuming a steady growth in development and expansion with these ET’s, which, again, there’s no reason to assume exists.

I’m not sure which assumption you think is invalid – ET, or the steady growth and expansion. If it is the expansion, let me point out that I am only assuming a non-uniformity of motivations for the various ETs. It only takes one with the desire to expand.

Why not? Why is 5 billion the magic number and not 10 billion? Who died and made you God?

Huh?! I am not claiming any ‘magic number’ or godlike status. In fact, I am arguing just the opposite – there is no ‘specialness’ to the 10 billion years it took for us to arrive at the brink of galactic domination. Therefore, ET could have accomplished it much sooner.

Gary Kumquat

1. If there’s intelligent life of roughly our tech level, it won’t have made much more progress in travel than we have.
2. If there’s intelligent life of a lower level, it will have made even less progress.

Using the definition of intelligence given in this thread, these two possibilities automatically place ET within 100 years of our current technology. This would mean that ET has matched our development within 0.000001%, which I find unlikely.

All it really says is that if there’s anything advanced enough to travel the universe, either it hasn’t gotten to our neighborhood yet, or it did so a long time ago and didn’t stick around, or it did and seeded the earth before departing, or it’s avoiding us, or it’s so damned alien that we can’t even comprehend it at our current level of knowledge, or…you get the idea.

Sure, I can dream up an infinite number of reasons to explain why we see no evidence of ET. If you find any of these particularly compelling, pick one or two and we’ll debate if you’re interested.

It seems to me the same underlying epistemology - that absence of evidence is not evidence of absence.

I do not claim that the lack of evidence means they definitely do not exist. But just as with unicorns and fairies, the absence of positive evidence eventually must lead us to a conclusion.

[Captain_Amazing]

*Originally posted by hardcore *
**Captain Amazing:

I’ve never been to China, and neither has any member of my family. Why not? You’d think if we existed, at least ONE of us would have gone to China. So, it’s a paradox…if I exist, why haven’t I travelled to China?

I’m not sure if you meant this as a joke. It doesn’t correspond to the Fermi paradox, unless your family is thought to number in the quadrillions. If so, it would be reasonable to expect that at least one of them had travelled to China.
**

Well, I DO have a big family. But, my point was:

Lets assume that there is another species of intellegent life in the universe. Lets also assume it’s 10 million light-years away, and they have ships that travel at light speed, so, hypothetically, they could get here in 10 million years. Now, the question comes up, “Why would they?” For that matter, why would they even know we were here? We first broadcast radio signals about 100 years ago. Assuming there’s no signal degradation (which we know to be false), nobody more that 100 light years out would be able to detect them.

The problem is, you’re making the argument:

1. If intelligent alien life existed somewhere in the universe, we would have the ability to detect their presence.
2. We can not detect their presence.
3. Therefore, no intelligent alien life exists somewhere in the universe.

I don’t understand, and most other people posting to this thread don’t understand where your major premise is coming from. Why is it neccesarily true that, if life exists elsewhere, we’d know? Look at history. Until European explorers came to America, native Americans didn’t know that Europe existed and Europeans didn’t know that America existed. Although both places had civilizations, they were ignorant of each other. Likewise, we and the hypothetical aliens on the other side of the galaxy wouldn’t neccesarily know, or have the technology to discover each other…the distance is just too great.

[Enderw24]

*Originally posted by hardcore *
**As I have previously indicated, it only takes 5 million years to span the entire 100,000 light-year distance of our galaxy, travelling at 10% the speed of light with a 10 light-year spacing between colonies and a 400 year latency period between expeditions. If ET only had a 0.1% headstart on us, he would have completely colonized the galaxy 5 million years ago while we were still chimps.
**

Whoa whoa whoa. Slow down there cowboy. The number of assumptions you’ve just made in this one paragraph alone are jarring, to say the least.

1. You’re assuming the alien colonizers haven’t met any other alien colonizers, had a war, killed each other off.

2. You’re assuming that we’d even be able to see these colonizations happening. At this point, our technilogical capabilities allow us to guess at the possibility of a planet around any particular star. We still really can’t see it. If we can’t see the planet, how in the world (ha!) are we supposed to see the aliens living on that world. Oh yes…their spaceships zipping to and fro. As I said above, as others have said above:
   The galaxy is freaking huge! Let me repeat that
   THE GALAXY IS FREAKING HUGE!
   Just how big are these hypothetical spaceships, that you don’t even think exist, supposed to be? May I refer you to
   The Oort Cloud which may be right smack dab in our own backyard. Or may not be. We don’t know. We’re still guessing on the reality of objects much larger than your hypothetical spaceships and much closer than your hypothetical spaceships.

3. The galaxy is not a straight line. There are three dimensions to travel out there. To say “It’s only 100,000 light years away from us so they surely must have come here already” assumes that they wanted to come straight for us. The logical (we are assuming these aliens you don’t believe to exist are logical, right?) assumption is that they would spread outward in every direction. That takes time. A long time.

4. You’re assuming that the colonizers colonized just because it’s there. Why not assume overpopulation on their planets? They colonized out of necessity. And so yes, they have 100, 1000, 10,000 planets under their empire. But that’s because they needed that many. They didn’t go exploring 100,000 lightyears away because it seemed like a good idea at the time.

5. Furthering on #4. If you were colonizing a planet, wouldn’t the point be to STAY on that planet? Or are we assuming that these aliens stay on a planet only long enough to gather enough raw materials to make it to the next planet?

[AHunter3]

The universe is really really freaking huge!

In addition to that fact, which is fact enough to explain matters all by itself, we are awfully freaking YOUNG.

I would tend to consider us to bear the hallmarks of a successful species. I would venture to guess that other intelligent species would also be relatively successful. Successful species on this planet have tended to stick around for many many millions of years. We are in our infancy. Perhaps, on the average, one intelligent species sends in inquiry capable of making contact with intelligent life on Earth once every, oh, let’s say, 500 thousand years. They didn’t catch any likely signals last time, so maybe the next time around?

[Epimetheus]

My take on it is that in the early development of an intelligent race, curiosity outweights knowledge, and being what it is, the so called emergent intelligence starts to try to explain things with limited understanding. Thus a sort of religion is formed. Religion is instrumental in the devlopment of intelligence, and opens the way for the empherical aspects of science. But science becomes complex, and difficult to learn for many.
The old primal instincs still existant in the intelligent creatures cause things like territorialism, Alpha complexes, carnal ownership(or the illusion thereof), and many many more of the more primative things we seem to be plagued with. These primal instincts are strongest as the species’ young are still developing, and cause problems in the learning processes while still in (alien) school. This causes an ignorance to form, and a fall back onto religion. As the species starts to make progress, the religion sees the change and is scared of it, and refuses to change to fit the advances. A mobacracy forms (otherwise laughingly refered to a democracy) and outlaws anything that seems immoral to thier religion. As things start going, the hand that brought them up to such heights starts to drag them back down, fearful that what it is holding will grow wings and fly off on its own, uncontrolled.
Oh, and throw into the equation a factor of selfishness, probably inherent in any species, as it is a good survial instrument, enter finacial problems.
The goverment runs off of money, just as businesses, and the mobacrocy that runs the various worlds start to get angry when taxes cut into their pocketbooks and seem to get wasted on ventures that have no immediate results. End space program.
Eventually the race never leaves the rock they evolved upon, or if they had left once, never do again. They live a happy, sheltered, comfortable life, never venturing out to where the poets and dreamers want to travel.
Ok, pessimistic, but I have never seen anybody suggest that perhaps sociological factors weigh into this. Perhaps the greatest flaw in intelligent life (similar to ours of course) is that we allow all to have a voice, and face it, A mob looses almot half of it’s collective IQ when it forms. It gets even worse when one factors in the fact that IL (humans at least)likes to form opinions even without full understanding.

So my bet is that other life has similar problems with their society/goverment. We will never get off this rock, never visit mars, never get out of this solar system. (We might consider it as the sun ages, and gets close to its death, but that is so far away in time, the chances we will end our exisitance ourselves or get hit with a meteor/comet in that time is too high)
Humans at least. Perhaps there is another race out there that has conquered this problem. At what sacrafice, who knows. Humans won’t. And I would wager that much of the intelligent life that forms out there and reaches our levels will be very, very similar to us.

(Sorry this post is so morbid, but I am just pissed at an article I read about a banning of human clonning and stem cell research. Damnit, I wanted to grow a new heart when this one went bad…Now I have to come to grips with death instead of hoping for immortality. Damn the Mobocracy)

[Enderw24]

Also hardcore, let me sort of play out a conversation we’ve been having with you in this thread:

Hardcore: Scientists haven’t seen any E.T.s yet. Here are all these theories on why they probably don’t exist. Prove to me they do.
Various Dopers: Well, it’s not difficult to imagine that with billions of suns across the universe…
H: No. We’re not talking about the universe. Assume that the aliens that don’t exist exist inside the Milky Way.
VD(heh): OK then. The galaxy is also really big. Billions of stars there as well. See, humans are just in the early stages of looking outward towards the galaxy, timewise. So we haven’t had much of a chance to check out what’s going on out there yet.
H: Well, if there were aliens, and they’re more advanced than we are, we surely would have seen some evidence of their colonization.
VD: What if they’re less advanced than we are?
H: Assume they aren’t.
VD: OK. What if they’re so advanced, they’ve converted their race into pure energy?
H: No, assume we can see them.
VD: OK, ever see The Abyss? What if they’re water dwelling intelligent creatures. They can still be quite advanced.
H: No, assume they live on land and can see the stars.
VD: Hmm…that throws the Nightfall hypothesis right out. OK, what if they don’t want to explore the universe? What if they’re just not interested?
H: Stop assuming so much! My made up aliens want to explore the galaxy but they may not exist. Prove that they do.
VD: Well, I guess we can also assume they haven’t killed themselves when they discovered nuclear power. OK, you know, as I said, the galaxy is REALLY huge and…
H: And my aliens love to colonize planets. And love to travel in spaceships for thousands of years on end. And they know we’re here so they’re coming in a straight line towards us.
VD: But…see, we can’t just assume all this, you see…
H: And they have three feet! And they have seven different sexes! And they wear pink on Saturdays! Why haven’t we found them yet? Huh?
VD: I dunno. I guess you’re right. The aliens don’t exist.

[hardcore]

Captain Amazing

Lets assume that there is another species of intellegent life in the universe. Lets also assume it’s 10 million light-years away, and they have ships that travel at light speed, so, hypothetically, they could get here in 10 million years.

If you’ll notice what I’ve said previously, I am trying to restrict this debate to our galaxy. 10 million light-years puts you out past the Andromeda Galaxy and closer to M81, Bode’s Galaxy. We’ll have enough trouble trying to detect ET within our own galaxy. I have no doubt there will be ETs in other galaxies, but the incredible distance between us won’t allow meaningful contact.

The problem is, you’re making the argument:

1. If intelligent alien life existed somewhere in the universe, we would have the ability to detect their presence.
2. We can not detect their presence.
3. Therefore, no intelligent alien life exists somewhere in the universe.

That’s not my argument at all. I’ll try to reiterate and make it easier to understand. Please keep in mind we are restricting this to the Milky Way.

1. If ET civilizations exist, some of them are likely to have a significant headstart compared to us.
2. Of the ET civilizations with a significant headstart, at least one of them would have the curiousity and desire to explore the galaxy.
3. The first ET civilization to embark on a colonization directive would find the galaxy open for exploration.
4. The colonization effort would happen in a relatively short timespan by evolutionary and cosmological standards.
5. The first ET civilization that colonizes the galaxy will by its existence naturally suppress any other life from attaining sentience.
6. We have found no evidence of a galactic empire, previous colonization effort, or even any intelligent ET civilization.
7. It is therefore likely that we are the first civilization to reach sentience in our galaxy.

Of course, this can by no means be an example of “airtight” logic, since by its very nature this discussion has far too much ignorance and too little evidence to be conclusive. I am merely advancing what I feel to be the most likely scenario based on the available data. But we cannot have a meaningful discussion if you do not at least understand my position.

Enderw24

1. You’re assuming the alien colonizers haven’t met any other alien colonizers, had a war, killed each other off.

What I am assuming is the first colonizers would by definition be the first. Therefore, they likely would encounter no resistance. (Isn’t resistance futile?) But even if they did meet another ET, they either:

1. Annihilate each other, which still leaves us alone.
2. One kills the other, thereby still being able to expand.
3. Each continues to expand away from the other, which would still resemble one large galactic empire to us anyway.

You’re assuming that we’d even be able to see these colonizations happening.

No, I think the colonizations would have already happened. What we would see (and hear) would be the constant daily activity throughout the empire. Plus the fact that I find it extremely unlikely they would have stayed away from our system entirely.

Just how big are these hypothetical spaceships, that you don’t even think exist, supposed to be? May I refer you to
The Oort Cloud which may be right smack dab in our own backyard. Or may not be. We don’t know. We’re still guessing on the reality of objects much larger than your hypothetical spaceships and much closer than your hypothetical spaceships.

The starships are easier to find than the objects in the Oort cloud due to their necessarily large unmasked energy release into the universe.

Zubrin used the figure of 1,000,000 tonnes to calculate the detectability over interstellar distances. He notes that if you reduce the figure by 2 orders of magnitude (10,000 tonnes), it only reduces the detectability by 1 order of magnitude. It is also significant to note that he believes if we focus our efforts on this type of search, we will find evidence of ET starship movement. As he states, and I wholeheartedly agree, “It’s worth a try.”

The galaxy is not a straight line. There are three dimensions to travel out there. To say “It’s only 100,000 light years away from us so they surely must have come here already” assumes that they wanted to come straight for us. The logical (we are assuming these aliens you don’t believe to exist are logical, right?) assumption is that they would spread outward in every direction. That takes time. A long time.

I am already assuming that the ETs would spread outward in every direction. This would be a colonization wavefront spreading in a spherical motion from the planet of origin. Therefore, I am calculating the movement of the wavefront through the widest part of our galaxy.

You’re assuming that the colonizers colonized just because it’s there. Why not assume overpopulation on their planets? They colonized out of necessity. And so yes, they have 100, 1000, 10,000 planets under their empire. But that’s because they needed that many. They didn’t go exploring 100,000 lightyears away because it seemed like a good idea at the time.

I’m afraid I don’t understand this objection. Maybe you could restate?

If you were colonizing a planet, wouldn’t the point be to STAY on that planet? Or are we assuming that these aliens stay on a planet only long enough to gather enough raw materials to make it to the next planet?

I am assuming an exploration of the frontier much like what we experienced on Earth. I used a 400 year average latency period, meaning the amount of time until the colony sent out explorers of its own. You can change it to a 5000 year latency, which makes the galactic effort take 50 million years, but I still think this is a virtual eyeblink on a cosmological scale.

I will refrain from responding in detail to your 7/26 9:57 CST post, as I think you may have been drinking prior to it. But I will point out that I am not asking anyone to “prove” ETs existence, since the only evidence I would accept would be scientific, which is not something we are likely to encounter in this discussion. All I am attempting to do is engage in an intellectual exercise and debate others about their preconceptions on the state of intelligent life in the galaxy. As I mentioned at the beginning of this thread, our ignorance far outweighs our knowledge on this issue. I am simply trying to use logic in conjunction with the small amount of data we do have and defend my preferred hypothesis.

Let me know if you feel there is a valid point in your imaginary discussion and I will try to respond to it.

[Enderw24]

*Originally posted by hardcore *
**

You’re assuming that the colonizers colonized just because it’s there. Why not assume overpopulation on their planets? They colonized out of necessity. And so yes, they have 100, 1000, 10,000 planets under their empire. But that’s because they needed that many. They didn’t go exploring 100,000 lightyears away because it seemed like a good idea at the time.

I’m afraid I don’t understand this objection. Maybe you could restate?**

Put yourself in the shoes of a drama director. What is the alien’s motivation? Find it. Embrace it. Love it.

OK, if we’re going to assume that these aliens must live in the Milky Way, must be more advanced than us, and must have ships that explore the stars, one of the few things left for us to question is why they’re exploring. Are they doing it because they’re curious? Perhaps they’re merely doing it because they need to. They breed like rabbits and the population on their planets fills up really really quickly. So they jump to a new planet when they fill up the old one. In this case, they’re not looking to go as far as they can, as fast as they can. They’re looking to stick around on one planet until they need to branch off into one or two more.
If so, the reason we haven’t seen them yet is because they have no need to travel 10, 20, 100 thousand light years out of their way, when all they need is the next planet over.

Besides, lets assume they are born explorers. They breed like rabbits and they just hippity hop from one planet to the next. If this is the case, they must be colonizing for something, right? For somebody? A home planet? 5 million years is a looooong time to be away from a home planet and 100,000 light years is quite a time delay in messages…even with a cable modem. Should we also assume that the need to colonize is somehow instinctual?

Oh yeah, and we shouldn’t forget that xenophobic races may use their technological superiority to create ringworlds or dyson spheres rather than going off and exploring.
Also, I wasn’t drinking. Just studying too hard. Tension breaker, had to be done.

[Badtz_Maru]

I think that most civilized races would spend a long time (by historical standards) in their home system before they felt any pressure to colonize other star systems. The cost is too high, unless some unforeseen development in science allows us to side-step the limitations on interstellar travel that physics give us. Even considering the possibility that most alien races would be unwilling to alter themselves to be able to survive in environments drastically different from the conditions on the planet they evolved on, there are too many better options that fit well with what we do know is true of the universe. It looks like overpopulation may cease to be a problem in industrial societies, look at the UN’s population projections, even the less conservative ones show the population stabilizing in a relatively short period of time. Even if a species did start colonizing their own solar system there would be a LOT of room - with colonization of asteroids, exploitation of the top few kilometers of suitable planet’s lithospheres, our solar system could easily accomodate hundreds of trillions of humans. If we allow the hypothetical race the possibility of changing their own physical nature we can blow that up to hundreds of quadrillions, or even near-infinite numbers if we find a way of transferring our consciousness to a different media.

What this comes down to is that an intelligent, tool-using race could easily expand their numbers for tens of thousands of years past our current level of development before they had to choose between limiting their reproduction or expanding past our solar system. We have no way of knowing how a culture would change over the course of that much time (look at how much we have changed in the last 10,000 years) so you have to be careful basing your guesses on what a race at this point would be like on what we know of the behavior of sentient beings at this point in time.

But what if there is a race that, because of some strange circumstances, does begin to colonize other star systems? Perhaps their very nature forces them to keep population density low and they can not (or will not) make the necessary changes to do the things I think we would do in our future if we keep expanding - let’s say that they will only live on the surface of habitable planets, they have no means of effective population control, and they develop the technology to send colonists to other star systems before they destroy themselves or get caught in a cycle of expansion followed by fierce wars that reduce their population to manageable levels. For one thing, with current knowledge it seems highly unlikely that space travel would ever reduce the pressure of population growth on a planet. Even with our population thousands of people are born a day, moving enough into space to make up for that would probably require many orbital elevators constantly carrying colonists to vessels that bus them to their new homes, whether in orbital habitats or (even less feasible) on the surfaces of other planets. And that’s not colonizing other star systems, just moving them around in the same system. It’s hard to imagine a civilization that can build STL starships fast enough to move tens of thousands a day to other star systems - even if they were all going to one star system 4 light years away and the ships were reaching near C en-route and turning around to come back for another load as soon as they got there, you are going to need at least 30,000 starships each capable of carrying 1000 people in rotation if we assume they are moving 10,000 people a day out of the system.

But let’s assume that they maintain a relatively low population density, have a an efficient means of moving their population out of the system, and spread relatively quick. Unless they are the only civilization in the galaxy, they are eventually going to encounter another. The odds are this civilization is not anywhere near the same age as theirs. What if they encounter one that’s only 50,000 years older than theirs, that reached the population densities I mentioned in my hypothetical example in the first paragraph? On one side you have a rapidly expanding loosely-knit (we’re assuming no FTL communication or travel) empire with thousands of ships, with a few billion beings each on various planets across their neighborhood of the galaxy. On the other hand you have a civilization of a trillion beings or so on each solid planet or moon in their system, a hundred trillion or so living in hollowed out asteroids, a hundred quadrillion vacuum-dwelling beings basking in the sun of the inner system and/or drifting in the cometary halo, and a google intelligences ‘living’ in quantum computers, probably experiencing thousands of years worth of consciousness each second. What do you think is going to happen to the fast-expanding warlord-types if the older civilization sees them as a threat (which they could be, eventually)? I have a feeling the races that can’t turn inward and make the most of the system they are in don’t last long once they start leaving their own system.

This is all assuming that life occurs frequently enough that several civilizations have risen in our galaxy. I personally feel that life is probably much rarer than that, and we could be the first.

[hardcore]

Enderw24, good luck with your studies. Try to avoid goofing off too much, or engaging in too many irrelevant theoretical debates. Lord knows what would have happened to me had the Internet existed when I was in college. Maybe I would have partied less. Yeah, right.

I haven’t assigned a motivation to the alien exploration, since any of the numerous possibilities will suffice. I do think it likely that one of the first few ETs to develop will be driven by the same insatiable curiosity that is characteristic of our species. In other words, we are not unique with respect to motivation.

Of course it’s entirely possible that all other ETs are within a few thousand years of us technologically and have yet to make it to the Alpha quandrant. Or they all want to stay home, or they are simply unable to mount a successful exploratory campaign, etc. I just don’t like the odds of any of these scenarios. But I do hope one of these turn out to be true. I don’t relish the thought of us not finding a similarly intelligent species among the stars in our galaxy. Not that I’m likely to be alive when it happens anyway.

[archmichael]

I think it is very interesting the assumptions that each person has chosen to attack.

1. If ET civilizations exist, some of them are likely to have a significant headstart compared to us.
2. Of the ET civilizations with a significant headstart, at least one of them would have the curiousity and desire to explore the galaxy.
3. The first ET civilization to embark on a colonization directive would find the galaxy open for exploration.
4. The colonization effort would happen in a relatively short timespan by evolutionary and cosmological standards.
5. The first ET civilization that colonizes the galaxy will by its existence naturally suppress any other life from attaining sentience.
6. We have found no evidence of a galactic empire, previous colonization effort, or even any intelligent ET civilization.
7. It is therefore likely that we are the first civilization to reach sentience in our galaxy.

Fermi seemed to think that aliens would be similar to us, and I agree with him. The problem I have is that he seems to assume that they would like to colonize and explore like we do, but he assumes that they would not have the problems we do.

1. All civilizations rise and fall: I think even alien civilizations will have this problem. When the civilization collapses, it would fracture into ‘warring states’. The ‘warring states’ civilization would spend most of their time looking inward until they unify into a new civilization. This situation would be exacerbated by a the lack of FTL communications and travel. A colony on the edge of empire that communicates with the capitol in terms of hundreds of years, would start governing themselves.

2. Motivation and resources for colonization: History has taught us that there must be a motive for colonization and exploration to take place. Perhaps in terms of the Galactic Empire we live in a very resource poor region. Exploration by curiosity is a very slow process. There are supposed to be regions in the Amazon where there exists tribes that have not had contact with the outside world. The tribesmen who live there don’t consider where they live to be resource poor, but for industrialized countries it is considered poor. The only people looking to make contact are private organizations like National Geographic, but it is a slow process because of the cost of conducting these explorations. Maybe a group of young tribesmen are lying in their hammocks having the same discussion we are having. One tribesman might be arguing that if there existed a ‘super-tribe’ with better tools, then they would have heard their drums far off in the forest, or would have made contact with our tribe. Since there has been no evidence, no ‘super-tribe’ exists.

3. Logistics of a galactic civilization: I firmly believe that a galactic civilization would have to have FTL travel, and instantaneous (or near-instantaneous) communications to be able to exist. So the ‘we have heard no radio chatter so ET intelligence does not exist’ argument does not ring true for me. I think that all our efforts like SETI are for naught. I think we are the Amazon tribespeople listening for jungle drums and looking for smoke signal, in a world of satellite phones. I think that if SETI ever finds a signal, it will be because some alien child went to the alien equivalent of a Radio Shack, picked up a radio frequency hobby kit, and sends out a message, “Hi, my name is XXXXXXXX. I am 6 planetary orbits old. Is there anyone out there?”

Sorry if I rambled. It is late.

[warmgun]

The single most complex machine ever invented by man is the modern rocket.It was not invented to colonize the universe. Or even spread humans through space BECAUSE WE CAN. It was a propaganda toy to ‘prove’ one nations superiority over another.
It’s amazing to me how even the most broad-minded posters here cannot think of other beings in ,at least, some type of earth bias.
No, I can not tell you what else might be out there. But I’ve got a strong feeling TV and movies have influenced our thinking.
If other ET developed and gained superiority as Mangout suggests by gobbeling up other ‘lesser’ species, their world and associated problems will be the same as ours.
Just because spreading through the cosmos is technically possible at a ‘certain’ rate is possible, that is a long, long way from it actually happening. ET’s have to eat. They would need funding (of course a ‘king’-based civilization wouldn’t, but then they never even conquered the world!), lots of natural resourses, etc.
Essentially what I’m saying is that the image of earthlike creatures living an elegant lifestyle with time, resourses, know-how, motivation and the thumbs-up from the masses is highly remote.
Heck, maybe everybody else is vegiterian…

[warmgun]

Oops…“Mangetout”, so sorry - it’s late.
And vegitarian…

[SPOOFE]

The reason we do not detect ET and his galactic empire is because they do not exist.

Specious reasoning. It is true that our lack of detection of a massive galactic empire can allow us to reasonably conclude that a massive galactic empire does not exist. However, we CAN’T conclude that other intelligent species do not exist, nor can we conclude that they haven’t mastered space travel.

The flaw in your reasoning, sir, is that the evidence you are presenting only indicates the nonexistance of a massive, galaxy-spanning empire. Nothing more. It says nothing about the possibility of slightly less-grand “nations” existing elsewhere in the cosmos, nor does it say anything about the likelihood of other intelligent species.

As other posters have hinted at, perhaps system-to-system space travel simply isn’t cost-effective. Or perhaps other species evolved in some of the globular clusters above/below the primary galactic plane, and as have expanses of tens of thousands of lightyears between their group of stars and the galaxy proper. Or perhaps humanity smells bad, and there’s a 300-lightyear quarantine zone surrounding our system.

[Gary_Kumquat]

*Originally posted by warmgun *
The single most complex machine ever invented by man is the modern rocket.

Now how arguable a starting point is that? Citety cite cite cite, please.

[warmgun]

Nova. They stated that fact flatly. But even if it’s not, it’s up there and the integrity of my point stands.

[The_Bad_Astronomer]

*Originally posted by Captain Amazing *
**I’ve never been to China, and neither has any member of my family. Why not? You’d think if we existed, at least ONE of us would have gone to China. **

If Chinese were wondering about your specific existance that would be a valid point, but a better analogy is that Chinese are wondering about the existance of Americans in general. Then, it only takes one Aemrican to visit China to prove that Aemricans exist.

It only takes a spacefaring race a few million years to travel to every star in the Galaxy. There are plenty of stars a billion years older than the Sun, so we can assume that there are planets like the Earth older than us too. Mind you, if evolution had zigged instead of zagged here on Earth, space faring beings might have arisen here millions of years ago.

So. Where are they? Maybe Earths are very rare. Or life is. But any assumptions you make based on psychology (aliens don’t like to travel, or keep us in a zoo) are suspect.

[Captain_Amazing]

*Originally posted by The Bad Astronomer *
**

*Originally posted by Captain Amazing *
**I’ve never been to China, and neither has any member of my family. Why not? You’d think if we existed, at least ONE of us would have gone to China. **

If Chinese were wondering about your specific existance that would be a valid point, but a better analogy is that Chinese are wondering about the existance of Americans in general. Then, it only takes one Aemrican to visit China to prove that Aemricans exist.**

Well, but there was a time when Americans never visited China. What I was trying to say was that the assumption the OP made, “The fact that we haven’t encountered aliens means they don’t exist” isn’t neccesarily valid.

[The_Bad_Astronomer]

*Originally posted by Captain Amazing *
**
Well, but there was a time when Americans never visited China. What I was trying to say was that the assumption the OP made, “The fact that we haven’t encountered aliens means they don’t exist” isn’t neccesarily valid. **

But then you have to play the time card. If Americans had good sailing vessels for thousands of years and not visited China, then something would be odd.

Again, the point is that if we are not the first, then we are unlikely to be the second, or even third. There are likely thousands of civilizations that arose before us, and only one is needed to fill the Galaxy in a short time compared to stellar and planetary lifetimes.