Have aliens visited earth?

[Alobar]

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id say its probable for other intelligent life to exist somewhere. getting here is highly unlikely.

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Actually, the conditions for life to exist are extremely rare. Life as we know it is extremely fragile and it appears, based on probabilistic arguments, that the conditions for life to exist are not that common in the universe. Microbes quite likely exist in abundance but complex life not. This argument was first set forth in the book Rare Earth: Why Complex Life is Uncommon in the Universe by Peter Ward, Donald Brownlee.

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even if its uncommon tho, the incredibly vast number of other stars/planets in the universe means its pretty likely its happened elsewhere.

[TheMainEvent]

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It doesn't seem almost equally unlikely that no form of intelligent life has ever formed on another planet?

Let's define "intelligence" as chimp-smart, just for laughs.

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My thinking was that simple organisms could live in a much more hostile environment/atmosphere than ours. It's like how people say if we have a nuclear holocaust, mammals would die but cockroaches would survive.

[Piz0wn0reD!!!!!!]

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Actually, the conditions for life to exist are extremely rare. Life as we know it is extremely fragile and it appears, based on probabilistic arguments, that the conditions for life to exist are not that common in the universe.

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while this may be true, the universe is extremely large and we really dont know that much about it relativley speaking.

[asofel]

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Considering the alien's obsession with SIIHP, I think its possible to assert that they are browsing OOT as we speak.

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BIMO

It's almost a statistical certainty that some sort of intelligent life exists somewhere else in the universe. That's a lot of planets out there, and that's just in our galaxy.

I don't care what those fools down in Roswell say. They got hoodwinked by the federales. You'd think we would have been contacted by an alien species before we were visited by one. They speak english, right?

ScottieK

[B Dids]

Given how much is out there we don't know, it's really hard to say what "life" even is.

It does seem kinda vain to think that we're the only populated planet in the universe, but it seems highly unlikely that we'll ever see any evidence to the contrary.

[HopeydaFish]

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I think if aliens did come to earth, theyd have the technology to make it so that we never saw them.

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I've heard people make this argument before, and I've always wondered what it would matter to them if we saw them? It's not like we'd be any sort of threat to them.

[MrMon]

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id say its probable for other intelligent life to exist somewhere. getting here is highly unlikely.

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Actually, the conditions for life to exist are extremely rare. Life as we know it is extremely fragile and it appears, based on probabilistic arguments, that the conditions for life to exist are not that common in the universe. Microbes quite likely exist in abundance but complex life not. This argument was first set forth in the book Rare Earth: Why Complex Life is Uncommon in the Universe by Peter Ward, Donald Brownlee.

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As the previous poster said, the number are just too big not for it to have happened elsewhere. 100 billion (10^11) stars in the Milky Way alone, probably 100 biliion galaxys. There are four worlds where life may originiate in our system alone (Earth, Mars, Europa, Titan). Say 25% of all systems have planets, so you've got 100 billion planets in the Milky Way where it has been/will be possible, 10^22 in the universe.

One could be vast orders of magitude off on probablity estimates and still have almost uncountable intelligent civilizations in the universe, let alone planets where there is mere life.

[MonkeeMan]

duh

[astroglide]

star trek seems to find no shortage of class m planets. agree to disagree!