The Fermi Paradox - Are we alone?

Drogheda445

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Following on from the previous thread which asked the question, "is humanity afraid of the dark?", perhaps we should consider who, or what, may live in the dark? Although the idea of beings from beyond our world has been pondered by some for centuries, only in the last century, as we have slowly uncovered our true place within the Cosmos, has the question of extraterrestrial life really taken a prominent place in the popular imagination of mankind. Now, we recognise that this world that we call our own forms part of a fairly ordinary solar system, not unlike the multitude of others that exist around most of the nearly 100 billion or so stars in our galaxy, itself one of perhaps as many as 100 billion galaxies in the observable Universe (the part where photons of light have had enough time to reach human eyes - about 13.8 billion years).

In the last 25 years, the number of known planets has grown from 8 to over 1000 as we have detected so called exoplanets orbiting nearby stars - only a tiny, tiny fraction of the overall number of stars in our galaxy, mind you. Vast swathes of the Milky Way remain uncharted, and the latest of our scientific probes to categorise the stars in the galaxy, the ESA's GAIA probe, will chart at best about 1% of them (1 billion in total). The technology for detecting exoplanets is so primitive in its development that thousands more so-called "candidates" have yet to be confirmed, and may not exist at all, such is the lack of precision when dealing with stars that are so incredibly far away. In terms of galactic exploration we are really are taking baby steps at this stage.

There can be no question, at least in cosmological terms, regarding our unremarkable status in the "cosmic arena". Although we have barely scratched the surface in terms of exploration, it is immediately obvious that our self-regarding notions of uniqueness are poorly supported. Of the minute fraction of planets we have observed, a handful of them appear capable of harbouring conditions similar to that of Earth. Surely then, given this extraordinary multitude of possibilities, even if chances of of life arising are very small, there are countless possibilities for it to get going elsewhere, either in this galaxy or certainly in the billions of others. And surely some of that has to be intelligent life which has acquired the ability to develop technology over millennia. And surely, even discounting all the reasons not to do so, some of them must have embarked on migration and must have spread out wards across the void? The numbers alone speak for themselves. There are, to quote Carl Sagan, "more stars in the whole Universe than every grain of sand on all the beaches of the Earth", so even if the odds are infinitesimal, they must arise at some point, especially over billions of years. And yet we still haven't found any of them, yet.

Where are they?

This mystery first occurred to the Italian physicist Enrico Fermi, well known for his involvement in the Manhattan Project after fleeing Mussolini's Fascist Italy. To him the fact that there has been billions of years of time, and that there are a sheer multitude of places, in which intelligent life could have arisen, would suggest that there has been ample time for an intelligent race to propagate across our galaxy and reach Earth, and potentially colonise it as well. In all of recorded history, and in all archaeological records, we see no evidence for this ever occurring. Even more startling is that since radio astronomers first started to listen for potential signs of alien transmissions, perhaps, they speculated, from massive beacons of energy, aside from one or two questionable occasions (such as the famous Wow signal), alien radio transmissions have never been found. The Universe appears to be silent, and organisations such as SETI, who were initially optimistic about what they expected to detect, have thus far been unsuccessful in their search.

In the rapid discovery of new worlds and the revelation of how truly vast the Cosmos is, this paradox seems totally baffling. At least until we realise that despite decades of extensive exploration, we still only know of one place where life exists, our own planet Earth. Many early astronomers once speculated that our nearest neighbours were home to people as well, but they have been shown to be barren and lifeless; Mars is a frozen desert whose liquid water has long since disappeared, the Moon has no atmosphere whatsoever, and Venus is a suffocating world with temperatures hot enough to melt lead. Life, from the massive number of worlds in our own solar system, as far as we know, has only arisen on one of them. Perhaps conditions for life really are very rare, and the chances of it actually occurring may be minimal.

Frank Drake, who was partly responsible for SETI's founding, posited an equation to estimate roughly how many intelligent alien races existed in the Milky Way galaxy, and which is usually written as N = R* x f(p) x n(e) x f(l) x f(i) x f(c) x L

N = Number of intelligent technologically advanced races.
R* = Rate of star formation in the Milky Way.
F(p) = Fraction of stars that have planets.
N(e) = Average number of planets per solar system that can support life.
F(l) = The fraction of habitable planets on which life actually develops.
F(i) = The fraction of planets with life that go on to develop intelligent, sapient life.
F(c) = The fraction of such intelligent species going on to emit radio transmissions into space
L = The longevity factor, how long on average do these advanced races continue to exist.

Its largely speculative, and while some estimates place the number into the thousands, some end up with a number less than one. The fact that there are so many unknowns in this equation makes it pretty much unworkable at this stage. It has often been criticised by some as optimistic, as it doesn't include other possible factors which may have helped life to develop on the early Earth (such as the presence of a large gas giant like Jupiter, which directed most life threatening asteroids away from the inner solar system).

Perhaps the fraction of planets with life, or life which goes into develop intelligence, are the factors which are vanishingly small. So far, given our preliminary discoveries, the first for factors appear to be relatively large. The L factor, however, is interesting. Are civilisations destined to last for millions of years, or do they usually end up going extinct as a result of their own technology. Its a question mankind has asked itself since the beginning of the Atomic Age, when we acquired the ability, at least theoretically, to wipe ourselves out by our own deliberate actions. Other risks which may not be as obvious are the result of technology making us advanced and interconnected; the possible spread of global pandemics, or our ability to control the climate. Is this the same with other intelligent beings. David Brin, an astrophysicist, also suggests the possibility of technological regression; that a civilisation chooses to destroy and hinder technological progress in order to consolidate the status quo and political control, a kind of Nineteen Eighty Four type scenario.

There are other things to consider however. The sheer size of the Universe, even for advanced civilisations, poses a problem. Radio transmissions from these civilisations, for instance, may not be strong enough to be received beyond a few light years, and may simply dissipate into noise, making any radio communication significantly more difficult. Even if civilisations are common, the distance between them means that radio messages (which travel at the speed of light), may take decades, centuries, or even millennia to reach their desired destination. We have only been broadcasting messages into space for a few decades, so the area in which human radio messages can be received is only a tiny portion of the Milky Way. Bear in mind that any radio response aliens make will take a similar length of time to reach us. The Arecibo Message, for example, was beamed to a star cluster 25,000 light years away, which means that two way communication will take something in the region of 50,000 years, an unfeasibly long amount of time.

Or maybe the use of radio as communication isn't common or is eventually discarded by aliens as their technological capabilities grow, a bit like carrier pigeons in the modern world of telephones and the Internet.

But why, if they exist, would they not visit us, even over billions of years? Even if restricted to sub-lightspeed, they should be able to cover much of the galaxy in at most a few million years. That's an issue that really depends on their intentions as intelligent species; are they automatically destined to expand and colonise anywhere they see fit? Maybe they are just so alien that the thought of growth and exploration doesn't even occur to them. Perhaps they have a sort of prime directive which prohibits them with interfering in the development of life in its primordial state, as on Earth. Some even crazier hypotheses suggest that we are being kept isolated deliberately until we reach a certain level of technology, like animals being observed in a zoo, a concept known as the Zoo hypothesis.

Michio Kaku, the world renowned astrophysicist and futurist, has stated that our expectations of being visited are extremely arrogant, and likened it to the expectation of a human being visiting an anthill and attempting to communicate with ants. To them, they may have absolutely no desire to contact a far more primitive species, who would probably not even recognise their attempts to communicate anyway.

This paradox does have a lot of possible explanations, but if I was to answer it, I would suggest that the sheer size of the Universe, coupled with the moral motivations of any alien civilisations, may explain why we have never, apparently, been visited. Perhaps when, in centuries or thousands of years to come, we begin exploring other worlds, we may decide against visiting them in order for life to develop, if it hasn't already done so. As for why we can't detect them, again, we've really only begun to scratch the surface. Out of 100 billion stars, we've only investigated several thousands of them at best. That's not even to mention the fact that there are an inordinate amount of possibilities in other galaxies, a fact which we've largely avoided talking about so far. Radio astronomy, as we've already discussed, is incredibly difficult over long distances, so unless we were to be directly contacted, we would likely not know of other civilisations just by listening out for them.

It's a fascinating, and in some ways unsettling thought, that we may be alone or at least incredibly rare. But the question of whether or not we are indeed alone is probably the most significant one in modern human society. If we are contacted in the foreseeable future, it would arguably be the most important event in all of modern human history. There would be so many ramifications for us as a species, politically, legally, in terms philosophy and religion, and in of our very understanding of ourselves and our origins. Mankind would never be the same again, even if it was mere confirmation of alien intelligence.

Arthur C. Clarke accurately summed up the significance of this mystery:

"Two possibilities exist; either we are alone in the Universe or we are not. Both are equally terrifying."

Its a thought to bear in mind whenever we marvel at the cosmic infinity of the night sky. Whether we are alone or not, we cannot help but be humbled by the profundity of the possibilities.

http://en.m.wikipedia.org/wiki/Fermi_paradox

Your own thoughts on what is arguably the greatest mystery of modern times?
 


Mackers

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So in effect there are enough stars in the Universe that might enable the same conditions as pertain here on earth for there to be another earth somewhere? Sounds like a goer to me. And that's without the mathmatics.
 

Clipper

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There is no real mystery, the idea that we are the only sentient lifeforms in the unimaginable expanse of the universe is utterly preposterous.
 

Radix

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Yeah, a bit like the idea that if you give a million monkeys a million typewriters, one of them is bound eventually to come up with the entire works of Shakespeare. The advent of the internet has of course disproved that particular theory. :)

On matters like this I think we should have open minds, after all, nothing is impossible to God.....
 
G

Gimpanzee

Great OP. My guess is that just like at every other turn of history, when people found out that there were others elsewhere that they didn't know about, that is the case once again. Why haven't we seen or heard from them? I suppose our attempts to rationalise this fall far short of what is required.
 

Half Nelson

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If life is so common then we should, by now, be able to create life.

After all, we have the finished product and all the building blocks. What's keeping us back?
 
G

Gimpanzee

If life is so common then we should, by now, be able to create life.

That's ridiculous HN. Let us say for argument sake that every planet in the Milky way was covered in slime. How would that imply that whatever slime existed on Earth should be able to create life? It doesn't. Nor does the new found ability of some species on one planet imply that the rest of the universe holds life. There is no connection between the two.
 

Half Nelson

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What is the effective radius within which our radio communications could have been received? 30 light years?

Rough calculations suggest that we have advertised our presence to 1.0273691131749815073559628503329e-26 % of the observable universe.

0.00000000000000000000000001 %
 

Radix

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If life is so common then we should, by now, be able to create life.

What's keeping us back?


Listen, you'll have to overcome your shyness and just ask her.

:)


Can he eat his own head?


Interesting you should pose that particular question because the rather paradoxical answer is yes, in light of the words of Jesus when he said, "the bread that I shall give you, is my flesh for the life of the world", while considering that we are his brothers and sisters, and he is the son of God.
 

statsman

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The quest for intelligent life elsewhere, fascinating as it is, might reasonably take second place to the search for intelligent life on earth. The latter's not going too well so far.
 
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Seanie Lemass

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There is no real mystery, the idea that we are the only sentient lifeforms in the unimaginable expanse of the universe is utterly preposterous.


As I said on another thread, an American scientist - Wright? - once said, "give us just one miracle (the Big Bang) and we'll explain all the rest" :)
 

Seanie Lemass

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What is the effective radius within which our radio communications could have been received? 30 light years?

Rough calculations suggest that we have advertised our presence to 1.0273691131749815073559628503329e-26 % of the observable universe.

0.00000000000000000000000001 %
There is also the possibility that as when you are stalking some woman through text (not suggesting for one moment that you would ever be such a cad :) that the recipients are saying "Don't text those mad fkers back. They'll all come over some night."
 

Socratus O' Pericles

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In terms of galactic exploration we are really are taking baby steps at this stage



And yet we still haven't found any of them, yet.

Where are they?




Or maybe the use of radio as communication isn't common or is eventually discarded by aliens as their technological capabilities grow.



Michio Kaku, the world renowned astrophysicist and futurist, has stated that our expectations of being visited are extremely arrogant, and likened it to the expectation of a human being visiting an anthill and attempting to communicate with ants. To them, they may have absolutely no desire to contact a far more primitive species, who would probably not even recognise their attempts to communicate anyway.


I think you are answering your own questions really. We can't even get the Internet to work properly and we are relying on beings with enough technical nous to navigate the expanses of the universe to contact us on the radio. The anthill simile may be a good one.
 

Socratus O' Pericles

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Listen, you'll have to overcome your shyness and just ask her.

:)






Interesting you should pose that particular question because the rather paradoxical answer is yes, in light of the words of Jesus when he said, "the bread that I shall give you, is my flesh for the life of the world", while considering that we are his brothers and sisters, and he is the son of God.
Yeah ! But can he make a rock so heavy he can't lift it.
 

Socratus O' Pericles

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The quest for intelligent life elsewhere,fascinating as it is, might reasonably take second place to the search for intelligent life on earth. The latter's not going too well so far.
I resemble that remark.
 


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