Have aliens visited earth?

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Just an FYI-
The pentagon does have detailed plans on what the initial response would be if aliens ever land on US soil. It was in an issue of Discover or Scientific American a while back.

Basically, if some sort of ship touches down the immediate area is evacuated. Juristicion goes to the FBI and the Nuclear Incident Response Team. Any beings on the ship are immediatly taken into custody by the FBI, and the NIR Team takes possesion of the spacecraft.

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I suppose this is marginally better than releasing a dove.

ScottieK

[CCass]

Of course they have been here before. Who do you htink built the pyramids?

[MrMon]

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Of course they have been here before. Who do you think killed the dinosaurs?

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[TimM]

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To everyone who hasn't seen Cosmos,

it's a brilliant mini series from Carl Sagan done 25 some odd years ago. I recommend seeing all 13 episodes, but there is one in particular, "Encyclopedia Galactica" I believe, that deals with this subject. Even today, it's extremely informative and a great watch. This episode even goes into the probability theories.

Check it out,
Ross

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Yes, I loved these shows when I was a kid.

The key variable in that probability, the assumption that makes all the difference, was "how long would a civilization last after it developed the capacity to destroy itself?"

[ChipWrecked]

Project Serpo

Not only have they visited, we did an exchange program with them.

(jk, but this is good reading if you like sf.... physics don't work right on Serpo, oh well.... [img]/images/graemlins/smile.gif[/img])

[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.

[mrkilla]

Also it's possible the speed of light has been reached By another being. Yes I understand very well E=MC2 thank you. However the fact remains there could possibly be a being that would be able to trancend this limitation [ Mass increasing as speed increases for all wondering why we can't reach it], either via force field or some other "alien" method.

Just because we can't doesnt mean they can't.

If they were able to do this theres a good chance that they'd have an undectable stealth tech as well.

[MonkeeMan]

Even if you didn't like Men In Black, just look around...they're everywhere man.

[TimM]

But how would they find us?

If complex life is common enough for highly advanced civilizations to be nearby, there would be many more planets with civilizations not as advanced, such as our own, also nearby. Many of these will be closer to them than we are.

If not, well, our own radio transmissions haven't gotten far enough from Earth yet to be received by anyone advanced enough to reach us. We've only been transmitting for less than a century, and 100 light years is not very far - 0.1% of the diameter of our galaxy.

Either way, finding us is like finding the proverbial a needle in a haystack. The only question is, are we one of many needles in a small haystack, or one of a few in a very big one.

[wacki]

murchinson meteorite

chiral proteins

CO2 cycle on mars. indicates life

Posted a million times.

http://www.space.com/scienceastronom...fe_050216.html

Not going to explain more. DOne it million times.

Oh, jason_t = full of [censored].