Have aliens visited earth?

[astroglide]

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

[Leaky Eye]

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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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There is another book called Probability 1 that makes the exact opposite argument. Both arguments are flawed by probabilistic calculations that ultimately contain a complete guess somewhere in their formulas.

[TimM]

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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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I have not read this book but I am aware of the argument. The problem is we really do only have a sample size of one for a lot of the assumptions being made. Many of the conditions for complex life they consider unlikely may not be so unlikely at all, and many of the conditions for complex life they consider necessary may not be so necessary at all.

[TimM]

jason,

Rather than argue with you, how about a deal? I will read Rare Earth and you can read Darwin's Dangerous Idea by Daniel C. Dennett. It's actually very good and I think you would like it anyway.

[jason_t]

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jason,

Rather than argue with you, how about a deal? I will read Rare Earth and you can read Darwin's Dangerous Idea by Daniel C. Dennett. It's actually very good and I think you would like it anyway.

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Thanks Tim but I've already read that book. If you have another suggestion I'd be happy to take you up on your offer otherwise I could reread it (it's been about 4 years).

[TimM]

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Thanks Tim but I've already read that book. If you have another suggestion I'd be happy to take you up on your offer otherwise I could reread it (it's been about 4 years).

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That's OK, I just thought he had some good points that pertain to this thread. I will take a look at Rare Earth and see what I think. I will probably be going in looking for ways to refute each point they make, but who knows, maybe I will be swayed.

[Alobar]

I think its pretty foolish to think we are the only life forms in the entire universe

I am unsure if any said life form has visited earth tho. I know there are tons of limitations that many argue make it impossible, but I also know we dont know all there is to know, so I definately think it could be possible. Im undecided tho, It wouldnt suprise me if it had happened, but I think pretty much all "crop circles" and "ufo sightings" and "governement coverups" are bogus. I think if aliens did come to earth, theyd have the technology to make it so that we never saw them.

[Piz0wn0reD!!!!!!]

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I think its pretty foolish to think we are the only life forms in the entire universe

I am unsure if any said life form has visited earth tho. I know there are tons of limitations that many argue make it impossible, but I also know we dont know all there is to know, so I definately think it could be possible. Im undecided tho, It wouldnt suprise me if it had happened, but I think pretty much all "crop circles" and "ufo sightings" and "governement coverups" are bogus. 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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it is certainly possible to travel insane distances in space. However to do said traveling would require much much more advanced technology and many resources.

If aliens did visit earth, why wouldnt they want to greet us? also if they were here, i wouldnt think the gov't would have the power to stop them or hide them.

[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.

[Alobar]

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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.

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probably because if we did see them, it would be the most significant event in human history. If there was undeniable proof that intelligent life was visiting this planet, it would cuase an uproar like nothing thats ever happened before.

If there is someone "watching" us it would make sense that they wouldnt want to be seen, because it would be traumatic and alter our course of history. I guess they might not care about that, but it just seems semi logical they would