http://arxiv.org/pdf/0907.3432

http://arxiv.org/pdf/0907.3432

Relevant link; http://en.wikipedia.org/wiki/Fermi_paradox

Its good Gary,
I didn't read all of it. I read about 15 pages and skipped to the summery.

I do like his final sentiment in the paper;
Milan M. Cirkovi says:

Resolving Fermi’s Paradox is not a luxury; rather, it
is one of the principal imperatives if we wish our scientific worldview to have
even a remote prospect of completeness.

I think its far too simplistic to say that there are no ET's because, if there were, we would have found them by now.

My personal thoughts are that we've only barely scratched the surface with our knowledge of cosmology and the universe. And we have only dipped our toe in the ocean when it comes to human searches for other life, intelligent or not.

Good paper Gary, thanks for the link!

John.

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Isn't saying that aliens don't exist because there's no obvious signs of life throughout the universe like early man knowing nothing about oxygen because they couldn't see it?

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Like Seth Shostak, I tend to dismiss the Fermi Paradox as a baseless proposition for two reasons:

a) They aren't here yet? That's like saying "There are no polar bears in my backyard and they've had THOUSANDS OF YEARS to get here and visit me, therefore they must not exist."

- There is no "paradox" here. The fact that aliens have not visited the Earth or are not present in our solar system (if indeed that's the case) is in no conceivable way incongruous with their possible existence or even the possibility that they are aware of our existence.

b) We haven't detected them yet? That's like scooping up a glass full of water at the beach, not seeing any whales inside your glass, and then concluding that whales must not exist in the ocean.

- There's no "paradox" here either. Earth's cumulative SETI efforts amount to a fairly "adequate" scan of a thousand or so stars out of the 200-400 billion in our Milky Way galaxy alone. Our conventional astronomical technology only just NOW, for the first time in human history has the capability to detect planets the size of Earth orbiting other stars (Kepler launched earlier this year), and even then that technology is still in its raw infancy. There is no guarantee that distant alien technology could be detected given the extremely limited capabilities of our tools and our nascent understanding of the universe (the foundations of modern astrophysics are less than a century old, younger than some people living on Earth today); we could just as easily detect alien technology and misinterpret it as one of the many mysterious "natural" cosmic phenomena for which we have only the barest shred of hypothetical explanations.

Heck, three quarters of the entire universe appears to consist of something we cannot see, cannot directly detect, and for which we have no credible unambigious explanation whatsoever; we call it "Dark Energy".

Humanity is like a blind man strapped to a chair in the middle of a vast desert. We can smell the air around us, hear within a certain distance, and directly touch the ground at our feet. We've come to the point in our history where we can describe our location and the area we can detect around us with reasonable accuracy; but to say we're completely and utterly "alone" in the entire universe is a bit premature.

May be we should call it lack of broad thinking paradox

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We choose to go to the moon and to do other things, we choose to go to the moon not because its easy but because its hard. kennedy

Well considering the topic here, we should try to play Devil's Advocate and consider all the possibilities. In science, its good to be sceptical.

1. Religion - Unlikely as it seems, but maybe a Divine creator made only one intelligent civilisation in the entire universe.
2. ?
3. ?
4. ?

[10 minutes thinking...]

Hmmmm..... My mind is corrupted, i can't actually think of any reason why there would not be other intelligent life out there somewhere. The overwhelming weight of statistics tells me that life is common and intelligent life is less common but it does exist.

The only limiting factor that i can see is our ability to actually detect other intelligence. Our current technology is a massive limiting factor, i do admit!

I see it like this; Going on the statistics of 1 intelligent life we know about, if it occurred once on this planet, there is absolutely no reason why it would not occur again in similar environmental conditions.

If, in the slim chance that we were put here on this earth by a God or Divine creator, then why would he have not done the same thing on another planet in another Galaxy. Either way, God, or a divine creator would be intelligent life other than ourselves! so that makes two if you believe in God.

Be sceptical guys, we need more debate and critical thinking.

John.

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Well considering the topic here, we should try to play Devil's Advocate and consider all the possibilities. In science, its good to be sceptical.

1. Religion - Unlikely as it seems, but maybe a Divine creator made only one intelligent civilisation in the entire universe.
2. ?
3. ?
4. ?

[10 minutes thinking...]

Hmmmm..... My mind is corrupted, i can't actually think of any reason why there would not be other intelligent life out there somewhere. The overwhelming weight of statistics tells me that life is common and intelligent life is less common but it does exist.

The only limiting factor that i can see is our ability to actually detect other intelligence. Our current technology is a massive limiting factor, i do admit!

I see it like this; Going on the statistics of 1 intelligent life we know about, if it occurred once on this planet, there is absolutely no reason why it would not occur again in similar environmental conditions.

If, in the slim chance that we were put here on this earth by a God or Divine creator, then why would he have not done the same thing on another planet in another Galaxy. Either way, God, or a divine creator would be intelligent life other than ourselves! so that makes two if you believe in God.

Be sceptical guys, we need more debate and critical thinking.

John.

How about #2 Long lived unbounded growth intelligent life civilizations aren't possible. Here I'm thinking of green house gasses and global warming. It may well be that smart civilizations are forced to limit their growth and population to a level where they never reach the ability to become super advanced.

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How about #2 Long lived unbounded growth intelligent life civilizations aren't possible. Here I'm thinking of green house gasses and global warming. It may well be that smart civilizations are forced to limit their growth and population to a level where they never reach the ability to become super advanced.

But Fermi's Paradox is a sceptical way of saying that there is no other intelligent life. If intelligent life occurs and dies because of climate change or nuclear destruction, that's different, then it did occur but just died out.

Being the ultimate sceptic, you could hypothesise that simple life is common, but intelligent life is not only incredible rare, but it is completely non-existent. You could hypothesise that the intelligence developed by the human race is completely unique. Maybe our intelligence is just a once off thing, never to be repeated. I'm only suggesting this to play Devil's Advocate, i don't believe it for one minute.

John.

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How about #2 Long lived unbounded growth intelligent life civilizations aren't possible. Here I'm thinking of green house gasses and global warming. It may well be that smart civilizations are forced to limit their growth and population to a level where they never reach the ability to become super advanced.

But Fermi's Paradox is a sceptical way of saying that there is no other intelligent life. If intelligent life occurs and dies because of climate change or nuclear destruction, that's different, then it did occur but just died out.

Fermi's Paradox does make the assumption that intelligent life doesn't die out. It also makes the assumption that it wants to go out into space. If the assumptions aren't true then there is no paradox.

Being the ultimate sceptic, you could hypothesise that simple life is common, but intelligent life is not only incredible rare, but it is completely non-existent. You could hypothesise that the intelligence developed by the human race is completely unique. Maybe our intelligence is just a once off thing, never to be repeated. I'm only suggesting this to play Devil's Advocate, i don't believe it for one minute.

John.

I could also hypothesize the intelligence we have is self destructive but all the rest of the life in the universe doesn't wage war on itself so it didn't have need to invent V-2 rockets. It also may have made the decision that beaming a beacon into space is a waste of resources. They may develop in a far different path than we did. I expect a bunch of paths however. Longevity may be tied to a path that doesn't send the civilization into space; one that may limit resource consumption unlike our unbounded path of the moment. Remember they are smarter than we are.

We don't yet have the ability to do more than a beacon but we aren't even doing that, so our lone data point doesn't suggest there is a paradox yet.

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There are many profound scientific reasons as to what type of intelligent life might live close to us in our neighbourhood of the Galaxy, if any, within 10-100ly.

Contrary to what is depicted on Star Trek and the like, maybe travelling linearly at light speed is the ultimate barrier.
Hence, no e.t. visitors.
The vastness of Interstellar distances is very difficult to comprehend.

My personal view is that in the Galaxy as a whole, life is plentiful, varied and suited to it's respective habitat. Life on earth is all we know, and from the earth's history, the development of species can take many twists and turns.
Assuming there is at least one planet in the habitable zone around most stars, multiply that by at least 100 billion for the galaxy as a whole and the result throws up lots of potential

Unfortunately, I have no way of proving it at the moment, nor has anyone else.

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*** Those who know, don't speak,
those who speak, don't know ***

My personal view is that in the Galaxy as a whole, life is plentiful, varied and suited to it's respective habitat. Life on earth is all we know, and from the earth's history, the development of species can take many twists and turns.
Assuming there is at least one planet in the habitable zone around most stars, multiply that by at least 100 billion for the galaxy as a whole and the result throws up lots of potential

Unfortunately, I have no way of proving it at the moment, nor has anyone else.

Hi Donegal_TDI,
Good to see you again buddy!

I tend to agree with your view. Despite the many parameters in the drake equation, i think its almost as simple as you suggest. In our solar system, one in 8 of the planets has life. Using that simple statistic, there are billions of other planets around other stars in the MilkyWay with biological life. Its only a matter of time before science can prove it.

The question of "Intelligent" life is more speculative, its more difficult to say if its a natural progression from simple biological life.

I think i also agree with you about the speed of light. Its possible that it is one of the main reasons why its difficult to detect "Intelligent" life. Its possible that physics and science will NEVER find a way to get around this. It might well be the universal constant that can't be beaten for any reason. There is so much that we still don't understand about cosmological physics.

John.

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My personal view is that life is abundant throughout the galaxy.
However,intelligent life may be quite rare.
Reptiles/Dinosaurs lived here for a very long time and seem to be the natural species to first evolve but apart from a few smart parrots, nothing really smart has ever been discovered, or survived, from that era so was an evolutionary dead end.
This scenario may be prevalent throughout the galaxy on planets similar to ours.
On the rare planets that intelligent life has evolved,
given sufficient time, they could colonise other planets near them.
This may be the scenario for the bulk of intelligent life,
same species on multiple planets.

A word of caution here, one possible reason that very advanced species may be deliberately suppressing any radio/communication signals is that they want to stay low profile to avoid attracting the attention of hostiles.
I strongly suspect that there may be a sentience out there we do not want to make contact with.
This is nature, the strong predate on the weak.

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*** Those who know, don't speak,
those who speak, don't know ***

I'm not a cosmologist, but it's always seemed to me that there's one critical element missing from discussions of the likelihood of "intelligent" life arising elsewhere in the Universe. We're fortunate to have evolved on a planet with around 20% oxygen in the atmosphere. This, combined with abundant woody vegetation allowed early man to create fire to heat his cave, cook food, and much later, extract metal ores to create primitive tools. But supposing that the predominant vegetation had been succulents? Almost impossible to burn, and so the ability to create fire would have stalled. Fast forward a few million years, and the ready availability of fossil fuels kick-started the Industrial Revolution. But without fossil fuels, how could any civilization possibly advance to a space age and then to interstellar travel? So, there's my thesis - for any sentient lifeform to evolve to an advances civilisation they would need an oxygen-rich atmosphere; woody vegetation and readily-available fossil fuels. Possibly a little simplistic, but what do others think?

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Succulent plants could be uprooted and laid out in the sun to dry, and then used for fuel. Succulents are generally common in sunny, semi-arid climates. Even in rain forests, people have managed to find enough burnable fuel to make routine use of fire. Michael

I think this theory assumes that for life to develop ,the exoplanet should be partially similar to ours, which is not neccesarily the case. first may be we would look at how fire projected us to were we are . I personally see its importance in three major ways and that is 1)as a defense against preditors 2)as a means for cooking which enabled us assimilate more nutrients than we would be able with out cooked food and lastly to enable us smelt iron ore , now thats our story. But the reality out there could be very different i.e the life forms though advanced may not nessecarily require oxygen to survive, due to the fact that even here on earth there various organisms which are actually killed by the presence of oxygen. Now that alone changes a lot of things because you even cant start imagining how different their biochemistry is , in that they may not require cooked food to attain intelligence in fact it may be to the contrary. As for the need for fire to make tools that again can be achieved in various ways, they might have used the natural heat near volcanoes to develop their tools and then possibly moved directly to the use of radioactive fuels at a later stage . Then again their is a possibility of the use of various abandunt natural fuels present on different planets not fossil fuels, but natural gases buried under ground like methane and ethane.they can be even able to generate the oxygen they require , if they are advanced enough after all there are various groups of civilizations. Then there is a possibility of them migrating to other near by planets that have what they require if for example two planets are close to one anther like earth and moon.

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We choose to go to the moon and to do other things, we choose to go to the moon not because its easy but because its hard. kennedy

Excellent review of the Fermi Paradox. Thanks for sharing !

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But Fermi's Paradox is a sceptical way of saying that there is no other intelligent life.

Some other alternatives:

1) The farther "up" the technological scale you go, the smaller the available audience becomes. For instance, if you throw a rock into a crowd, anyone can "receive" that message, but if you use a cell phone, only someone on the same technological level can receive that communication attempt.

2) Assuming any world will have finite resources and that life expands to fill every nook and cranny possible, maybe the only way to survive long term is to abandon the never ending cycle of more-newer-more-better-more-faster-repeat.

3) "They" don't really want to talk to us or be discovered!

Martin

2) Assuming any world will have finite resources and that life expands to fill every nook and cranny possible, maybe the only way to survive long term is to abandon the never ending cycle of more-newer-more-better-more-faster-repeat.

Martin

I like your point No.2, it makes sense!

We can clearly see how evolution has worked over time. In any species, a character trait that gives you an advantage over the others will do well. But evolution also takes a very very long time to fine tune any character trait, hundreds of thousands of years.

We as humans have only become really clever in very recent times, so evolution has not decided yet if being really clever is a "good" genetic trait. Maybe in time when we destroy ourselves with our own clever curiosity, nature will reset the clock and cleverness and conscience intelligence will be history.

Maybe Fermi was right!, Maybe there is very little intelligent life because any time it develops, it gets too enthusiastic with technology and destroys itself.

John.

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actually evolution has been proven to move in jerks and spurts. It hasn't been a smooth transition over time. More of a kick start when a population becomes stressed

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In a rich man's house there is no place to spit but his face.
Diogenes Of Sinope

actually evolution has been proven to move in jerks and spurts

I can believe that.

For now, I just hope we can keep SETI and Hubble going!

Martin