Most likely. However I am referring to one planet, and a planet has a finite lifespan in which it will receive enough energy for the anti-fire known as life.

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Yes, and I wasn't clear- I agree that it is not an inevitability.

Thank you. I was fairly sure that was what you meant after I posted my missive. Thank you very much for the clarification.

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Actually, this could also be incorrect. The Fermi Paradox is based on a notion of alien "civilizations" that conform to our concepts of what a civilization is. As brilliant as Mr. Fermi was in many areas, he and his colleagues were discussing 1940s comic book aliens who, no matter how strange they were drawn, were essentially advanced reflections of us. Fermi failed to consider what "alien life" might actually be like. Because of this, in terms of our understanding of biology, one could just as easily imagine a galaxy teeming with advanced alien life and not one of them comes here or contacts us in all the years of human evolution so far. There is nothing in nature to preclude that or make it any less likely. It is no more likely or unlikely than rare aliens. Though we can make informed speculations based solely on our understanding of chemistry and biology on Earth, thus far the real answer about life elsewhere in the galaxy is: we don't know.

If one objects to this notion, then one has to introspect and admit that you are embracing a concept of aliens that think like us and are essentially reflections of us. But in reality, if they exist, they're aliens, so they are not obligated to be like us at all.

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"Insignificant molehill sometimes more important than conspicuous mountain." - Charlie Chan

I suppose that one premise of the Fermi question is not so much that complex phenomena elsewhere are likely to resemble us (I'd guess that mostly they don't, if indeed "they" exist, or even that "they" is a suitable pronoun), but that somewhere in the galaxy there might be, just perhaps, even a very few analogous cultures.

Right, but let's be honest: a civilisation that keeps to itself and does not attempt to travel across the galaxy or communicate with others is not what most of us would consider an "interesting" alien civilisation, is it?

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"A witty saying proves nothing" Voltaire.
"All your bias are belong to us" Ara Pacis.

As might have been pointed out before, Fermi's paradox only addresses the absence of expansive civilisations; it says nothing about the stay-at-homes, except to ask why, if they exist, they all stay at home.

A universe full of stay-at-homes who have formed a galactic society using long-range communications would be an interesting place to be. If communications were efficient enough vast amounts of information could be shared between systems, including all the information required to replicate individuals at long distance. You (or a good copy of you) could travel to distant alien worlds effectively a the speed of light, with no subjective time elapsed during the journey.

This may even be yet another solution to Fermi's paradox- the aliens won't arrive until we can build a device to receive them.

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Wouldn't we? I wonder about this. Assuming, and it's a large assumption, that there is something in common between us and this culture, I would have thought it could be just as interesting, perhaps more in some ways, as hypothetical cultures with a closer match.

Are you equating "stay at home" with "not coming to Earth today"? Because all we can say is that we don't have evidence for ET civilizations within the limits of our current observations. We can only speculate about whether or not there are interstellar civilizations.

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I agree with you, I dont think its inevitable, unless given an infinite amount of time (for the whole universe). I just think it's very likely, given the right initial conditions and environment. Now, how common and likely are these conditions across the Universe and how much of a tolerance does life have for conditions even slightly different-- i.e., K or F type sun's (or even other types of stars), or planets somewhat warmer or colder than ourselves, or multiple stellar systems-- that is anyone's guess. My thoughts are that there are forms of life (even intelligent life) that are so different from us, because they exist in completely-- alien (for lack of a better term)-- environments, and took a completely different evolutionary path (as life would have done even here had even one of these mass extinctions not occured), and might have been evolving for tens of millions of years, or even billions of years, longer than life on earth has. Would we even recognize it as intelligent life, or even life period? In short, in our universe, there might well be a universe of possibilities.

I like this way of thinking... it provides a nice lead in to the "Prime Directive" that we will not be able to detect ET unless we, ourselves, are at the right point in our scientific and technological evolution in order to do so. The universe full of stay-at-homes you are talking about reminds me to what's happened to our world since the internet has developed and evolved! :P

The idea of teleportation you've discussed is an interesting one... that MIGHT be the technology we need to develop in order to detect and receive them... before which, they have deemed us not worthy of attention. Perhaps, they dont want to tamper with us-- who knows.

Or maybe they are stay at home because they are waiting for people to call. Bogged down with funding issues, when there are more 'important' things like national defense, they are labeled kooks and resource wasters. At most they somehow drum up the effort to send a small group of beings to the nearest astronomical object, only to have their funding cut. In some of the worlds, science continues with probes and telescopes, while others listen to the heavens, waiting. However, all efforts to create a second home are labeled fantasy and a travesty when 'there are more important issues down here'. Finally the technological civilization collapses, either in slow decay, or in fire, or under the its own unsustainable weight, it collapsed, like all civilizations do. Then disaster strikes, maybe a few days before a new light was seen in the sky, and the sky burned, or maybe some disease broke the locks on their immunity, or some other calamity, or maybe evolution washed them over, or however, and the brief spark of mind, was over.
As of yet, this may be the fate of all intelligent life, or something like it. For all we know, a technological civilization may be just as rare as intelligent life is compared to any other kind. Or that we will ever spread throughout the heavens. Or that all are listening, but none are speaking. All life fears its death, are we ourselves brave enough to truly live?

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The point is - if aliens exist, it is just as likely that all of the advanced ones (that are not extinct) have never come near us as it is that aliens are very rare and/or extremely far away, outside our galaxy.

Also, we don't actually know what a civilization is when it comes to speculations about nonhuman extraterrestrial life. It is parochial to assume "alien civilizations" are going to be anything like us, even remotely. It is better to speculate about extraterrestrial life as a whole rather than presume aliens would be anything like human civilization.

Though we don't know that aliens exist, we do know so far that the basic elements of chemistry upon which life is based exists in deep space and that in itself is a minuscule step toward an assumption that life forms have likely evolved elsewhere in the galaxy. Other than this, and until there is more evidence, we don't know if or how advanced aliens exist regardless of whether they have visited us or not. There is nothing in nature or evolution that dictates that advanced aliens of any kind must travel in space to us.

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"Insignificant molehill sometimes more important than conspicuous mountain." - Charlie Chan

You appear to be saying that if advanced alien civilisations do exist and are relatively nearby they have simply not come to our system? The question is - why not? There are many possible answers, and perhaps that really makes it pointless to even ask the question without further information.

But in my opinion the question does still remain an important one. We aren't seeing evidence of a massive, ancient, all-pervading civilisation.

Perhaps we just don't recognise the signs; m1omg suggested that an advanced civilisation might be unrecognisable and therefore invisible to us.

It might, for instance, colonise the deep hot biosphere beneath our feet; I have read an estimate that the mass of that deep hot biosphere is greater than the surface biosphere. We might just be the irrelevant scum that lives on the outside of the planet to such a civilisation. Or a civilisation located inside gas giants, or even inside stars, could have colonised the Galaxy long ago. But that would leave an opportunity for a second advanced civilisation to arise, one consisting of surface dwellers, one which is not affected by the deep hot biosphere, or stellar, civilisation and may not even know about it. We should be able to notice the second civilisation, as it occupies the same sort of environment as we do.

The question could then become - what has prevented this second civilisation from arising? Does the existence of the first civilisation inhibit the second? An invisible and exotic civilisation (or several different ones) might pervade the Galaxy and somehow prevent recognisable civilisations from arising. The older, and invisible civilisation might even absorb the non-invisible civilisations; life in an invisible civilisation might offer so many benefits that it would be foolish to reject the offer. Even this would represent (to get back to the original post ) a 'filter' of sorts - developing but visible civilisations are contacted by invisible ones and given the opportunity to join them in blissful invisibility.

Or perhaps visible civilisations simply destroyed as they arise (for some unnown reason). In which case we should ask ourselves- are we too visible?

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There is nothing in nature or evolution that would force extraterrestrials of any kind (if they exist) to travel in space to us. Fermi was thinking of pulp fiction and comic book aliens in science fiction civilizations based on empires, values and technology from human history. It is just as likely that the galaxy is teeming with alien life, none of which has traveled here, as it is that aliens are very rare.

And we do not know what an extraterrestrial civilization is because "civilization" is solely a human concept. It is like saying "alien automobiles" or "alien uniforms" - if these seem comical it is because we assume "advanced alien civilizations" can beam themselves around and don't need old-fashioned automobiles, just as we rarely use horse drawn carriages and in the future might develop advanced transport systems. But in reality, all of these "advanced alien" notions are an extrapolation solely of human history applied to hypothetical advanced aliens.

Most people when discussing possible alien life are inferring their existence or behavior based entirely on known human values and human history. This leads to a cul-de-sac.

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"Insignificant molehill sometimes more important than conspicuous mountain." - Charlie Chan

But what would stop them? That is the question. From a hypothetical population of diverse extraterrestrial civilisations some may be expansionist; those are the ones we would expect to see. Our experience of intelligent civilisations should show a bias towards the expansive ones- yet we see none.

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Why should we assume that some may be expansionist? That would assume that the tendency to expand we see on Earth is, if not universal to life at least found in some other species, and we have no way of knowing if that is the case.

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"You miss 100% of the shots you don't take" - Wayne Gretzky

Well, we could assume that expansive civilisations are rare, but I am trying to avoid making such assumptions. We simply do not see them, and that poses a question which we can't answer without more information.

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For the purposes of this discussion civilisation may be defined as an entity or group of entities which uses intelligent action to to perpetuate its own existence. We cannot make any assumptions about such entities apart from that. Such civilisations might be very diverse, from AI units to intelligent bacteria, and anything between. But unless they use intelligent acton, they are not really a civilisation. I think we just about qualify by this definition, ourselves. And civilisations which don't perpetuate aren't around for very long, so we wouldn't expect to see them.

Not all civilisations would be expansive; but we can't assume that none would be- and we would expect to see more instances of an expansionist civilisation, since they might be expected to occupy a large proportion of all the suitable locations in a galaxy after a few millions, or a few tens of millions, of years.

However, as Landis has pointed out, not all expansionist strategies would mean that every location in a galaxy would eventually be occupied; it may be the case that each colony can develop in three ways- to die out, to enter a steady state, or to establish a new colony. If the chance of each outcome is the same, the overall expansion eventually stalls without colonising all of the Galaxy. And of course there are many other options.

One other alternative to all-out expansionism is to establish one single optimum colony in a prime location. Some red dwarfs are expected to persist for a trillion years or more- if a civilisation wants to avoid the eventual demise of its own G-Class star (or whatever) it could colonise a sngle nearby red dwarf and perpetuate happily for a very, very long time.

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I think one of the few assumptions we can reasonably make about life in general,
is that it has to be expansionist to a certain extent in order to survive and evolve.

Species that never go beyond their original habitat tend to go extinct faster.
They also have fewer pressure to evolve than the expansionists.

They might be really careful (like the puppeteers, for example) and rather build their own worlds or keep down their numbers artificially than expand.
Unlikely, but possible. Culture amounts for a lot.

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"Half of what I say is meaningless, but I say it so that the other half may reach you."

But those assumptions are based on our single sample. That is how life works here, but do we have any indication it must work that way elsewhere? We really need to find some elsewhere before we have enough data to work with.

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"You miss 100% of the shots you don't take" - Wayne Gretzky

Without making any assumptions at all, a life-like phenomenon which increases in volume will be more prevalent than one which does not. So, although we might find instances of life-like phenomena which do not increase in volume, they will be rare compared to the instances of once which do increase.

I can't think of any instances of life on our planet which do not grow in some way or another, and it is difficult to imagine how life could exist without growth- but perhaps such a phenomenon might exist somewhere.

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I suppose that we could speculate that if a biosphere produced a culture that was essentially memetic, rather than genetic, then it might find enough advantage in miniaturisation to shrink overall.

Not really - think stable population in an enclosed system.
There are examples of animals changing their reproduction rate depending on surroundings.

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Si tacuisses, philosophus mansisses.

"Half of what I say is meaningless, but I say it so that the other half may reach you."

Difficult to imagine is the point. If it's alien then it may be truly unimabinable.
What if life on Earth just happens to be the one form of life that fills its available volume, with the rest of the universe following a completely different, unimabinable pattern?
We have no way of knowing at this point.

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"You miss 100% of the shots you don't take" - Wayne Gretzky

Then isn't that like saying the world is full to the brim with coffee pots, and anything we don't recognize as a coffee pot is merely a coffee pot in an unimaginable form. Take this thing on my desk I like to call a 'computer'. I can't imagine it as a coffee pot, the very idea of it being a coffee pot is unimaginable and very silly idea to me. But then, could that not merely be my limited human perspective? After all, who knows what other coffee pots there could be, we only have a very limited sample right here on earth, and we have no way of knowing if coffee pots are mostly like the ones here, unique to this world, or come in such in an unimaginable shape and form, that if we ever came across one, we wouldn't recognize it as a coffee pot. It would be the height of arrogance indeed to think that the coffee pots of the universe would be anything like OUR coffee pots. After all we only know what we know here, confined by our own minds, unable to perceive the coffee pots of other worlds for what they truly are.

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I suppose we may, or may not, discover (or be discovered by) a range of complex phenomena and entities from, "yes that's life although not exactly like us", through "it's life Jim, but not as we know it", and "wow, that's complex, but what is it", to "!".

I see no reason to rule in or rule out anything in that spectrum, nor a way to guess at the probabilities of the various possibilities. It, whatever it is, may be similar, it may be different, but I'd guess we could easily encounter both and neither.

Hey, if you want to believe the universe is full of wierd, unrecognizable coffee pots we really don't have any way to prove you wrong at this point.

My point is we only have one sample case for how life should behave, and no idea how unique or common it is. If we start saying things like "life needs to expand to fill its volume" then we are making a broad assumption based on one data point.

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"You miss 100% of the shots you don't take" - Wayne Gretzky

And I agree with that. But on the other hand, we DO have that one data point. We have a living vibrant world, full of all manner of creatures, and there are others in the past even more varied. And it is form that on which we judge life. We quite possibly may find things that make us go '!'. And those things won't be life. They will be 'something else', and we will make metaphors and analogy's, and simplifications, just like we we use the flatlander story to try and understand higher dimensions. Hopefully we will be able, if we bend out heads like a spoon, to understand enough that we don't put the rest of the universe in the miscellaneous pile.

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