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Post by grashtel on Jun 5, 2007 9:58:01 GMT -4
And of course, long before that, we need to find someplace to send it, first. I can't see a use for generation ships other than colonization. There are lots of good places to send a generation ship, most of the stars we can see are probably good targets. Once you can build generation ships you don't need planets anymore, by its very nature a generation ship is a viable space colony so all you need is a decent asteroid belt and you can have more habitable volume than dozens of planets.
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Jason
Pluto
May all your hits be crits
Posts: 5,579
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Post by Jason on Jun 5, 2007 11:16:01 GMT -4
I would prefer to wait until we have a good planet as a target.
I think you're overstating things a bit on generation ships not needing planets anymore. A population in a generation ship is stagnant - they can't grow beyond the bounds the ship will allow, and they will have access to very limited resources.
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Post by Bill Thompson on Jun 24, 2007 16:58:00 GMT -4
There's an old saying that goes "absence of evidence isn't evidence of absence" and that pretty much sums up my thoughts on Fermi's Paradox. The fact that we haven't discovered any sign of extraterrestrial life isn't evidence that there isn't any. It just means we haven't looked in the right places, or that we didn't recognize the signs when we saw them. Absence of evidence is evidence of absence in a court of law. The Burden of Proof should fall on those who claim something exists, not on those who claim it does not exist. Otherwise, we are all just living in a fantasy world and it is perfectly acceptable to believe in any thing that gives us pleasure to believe in. It is not possible to prove a negative. It is not possible to prove that something does not exist. For example, I could claim that Santa Claus exists and challenge you to prove that he does not. It would not be possible for you to do so. You could fly me to the north pole and say that this proves he does not exist because he is not there. But I could say that he knew you were coming and so he is hiding. The same seems to be the logic of those who believe in ETI elsewhere in our galaxy. There is this reason or that reason why they are not just walking down the street as Enrico Fermi suggest should be happening. Sure you can have faith in the existence of ETI and, sure, you can use good and beautiful sounding poetry like "absence of evidence isn't evidence of absence" but it is not good science. What science says is this. The areas that for life to thrive in our galaxy is a continually shrinking region that we recognize as we learn more and more. It is not just a narrow ban around our star, it is also a narrow ban within our galaxy. We live in a universe that is hostile to life. It is not life-friendly. Also, if it was not for several things on Earth existing just right, we would not be here. Our solar system formed from another, and a much larger star. We have this to thank for the existence of heavy metals. Without that, the earth would not have a heavy metal core to generate a magnetic field that keeps deadly radiation away from us. These are just some examples. There are more.
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Post by LunarOrbit on Jun 24, 2007 17:17:07 GMT -4
The Burden of Proof should fall on those who claim something exists, not on those who claim it does not exist. Who is claiming that ETI exists? Not me, and not SETI. Wanting to search for ETI based on the possibility that it might exist is not the same thing as claiming that it does. It appears to me that SETI takes the agnostic approach... they can't prove that ETI exists, but they can't rule it out either. That is a safe and scientific position to take. You take the atheist approach... we haven't proven that alien life exists therefore you believe it doesn't, and that doesn't seem very scientific to me. If you can't prove with 100% certainty that something doesn't exist (and how can you?) you have to leave open the possibility that it does. It's ridiculous, in my opinion, to say with certainty that alien life does not exist in the universe if you haven't explored every corner of the universe (past and present) first. And since life has popped up on at least one planet in the universe... this one... there's no reason for me to believe it hasn't happened elsewhere. It is not possible to prove a negative. It is not possible to prove that something does not exist. You're absolutely right, you can't prove that something doesn't exist... and yet here you are claiming that a math equation proves that alien life does not exist. Do you not see the contradiction in your arguments? People have calculated that it would be impossible for Santa Claus to visit every home on Earth (even if he limited himself to just one religious group) in the time alloted. If mathematics can be used to prove aliens don't exist then surely it can be used to disprove the existence of Santa too.
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Post by Data Cable on Jun 24, 2007 18:38:10 GMT -4
Absence of evidence is evidence of absence in a court of law. I'd like to see a citation on that one. Searching for evidence that something exists does not constitute a claim that it exists. But we can't yet "fly to the north pole" where ETI are concerned. We can just barely discern that there is a "north pole." What you're claiming is that because Santa didn't show up in your living room, he must not exist. Water buffalo are not just walking down my street. Does that mean that water buffalo do not exist? Why must ETI behave as Enrico Fermi suggests in order for them to exist? The equivalent prose from your side would seem to be "If it ain't here, it ain't anywhere."
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Post by Bill Thompson on Jul 17, 2007 17:46:49 GMT -4
Absence of evidence is evidence of absence in a court of law. I'd like to see a citation on that one. Searching for evidence that something exists does not constitute a claim that it exists. But we can't yet "fly to the north pole" where ETI are concerned. We can just barely discern that there is a "north pole." What you're claiming is that because Santa didn't show up in your living room, he must not exist. Water buffalo are not just walking down my street. Does that mean that water buffalo do not exist? Well, if a tree falls in the woods and there is noone around, for all practical purposes, it did not make a noise. If there are ETI in our galaxy they are hiding for one reason or another and for all practical purposes, they are not there. To me, that is the spirit of Fermi's Paradox. As for absence of evidence in a court of law, if the galaxy was on trial and if it was a crime to have another planet with life on it like ours, the galaxy would be proven innocent.
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Jason
Pluto
May all your hits be crits
Posts: 5,579
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Post by Jason on Jul 17, 2007 17:56:32 GMT -4
"Why are you screaming so loud?" "I'm scaring away the alligators!" "But there aren't any alligators around here!" "Works pretty good, doesn't it?"
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Post by LunarOrbit on Jul 17, 2007 23:13:53 GMT -4
Well, if a tree falls in the woods and there is noone around, for all practical purposes, it did not make a noise. Of course it did. Whether someone heard it is irrelevant to whether it made the noise. When a large object (like a tree) falls and hits another large object (like the ground) the resulting vibrations travel through the air... noise. This happens whether or not there are a pair of ears nearby to detect it. Again, our inability to detect the ETI is irrelevant to whether or not they exist. Their existence is not dependent on our knowledge of them. Then Fermi's Paradox is one of the most ridiculous things I have ever heard of. Does the food in your refrigerator disappear when you close the door, or is it still there despite your inability to see it? Does the universe cease to exist when you close your eyes? Seriously, it is pretty egotistical to assume that the universe needs Bill Thompson to be there to witness it in order for it to be real.
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Post by Data Cable on Jul 18, 2007 1:27:19 GMT -4
Well, if a tree falls in the woods and there is noone around, for all practical purposes, it did not make a noise. And if the sound waves travel far enough to be detected by a sensitive listening device, and said waves haven't yet reached said device? No, the galaxy would be found "not guilty." And no, legally, absence of evidence is not evidence of absence. If the prosecution hasn't recovered a murder weapon, the defense can't use that as evidence that there is no murder weapon. And unlike the law, science has no "speedy trial" or "double jeopardy" requirements, so just because we didn't find any evidence today doesn't mean we can't look/listen again tomorrow.
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Post by Bill Thompson on Jul 18, 2007 13:46:57 GMT -4
Well, if a tree falls in the woods and there is noone around, for all practical purposes, it did not make a noise. And if the sound waves travel far enough to be detected by a sensitive listening device, and said waves haven't yet reached said device? You mean a "sensitive listening device" like an ear? That would be the same thing as being heard. Look, let's just look at the facts. As Fermi clearly observed, human beings went from building huts to building Saturn V rockets in a few thousand years. By any logical estimate made by reputable scientists, it will take less than one million years to colonize the whole galaxy. And the galaxy has been around for billions of years. Now, you can lead a horse to water but you cannot make him drink. So, as long as you can do the math and as long as you can see where this all adds up to, the outcome is clear. If intelligent life like us is abundant in the Galaxy as Frank Drake claims, they should be all over and the Seti@home project should have gotten countless hits by now. For all practical purposes, it is more than logical to assume that we are most likely the only ones like us in the galaxy. You can say, "oh, they are hiding" or "oh they are intelligent but not intelligent like us" well, that is just fudging with the facts. Goats and dogs are intelligent, but that is usually not what people mean when they think of ETI. This goes into statistics and probability. If you cannot visualize the difference between a million year and a billion years, then maybe Fermi's paradox does not have the impact on you that it has had on me. No offense, but I have to wonder about people who do not think Fermi's observation means anything.
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Post by Data Cable on Jul 18, 2007 14:32:12 GMT -4
You mean a "sensitive listening device" like an ear? No, I mean much more sensitive than that.
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Jason
Pluto
May all your hits be crits
Posts: 5,579
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Post by Jason on Jul 18, 2007 15:20:23 GMT -4
Look, let's just look at the facts. As Fermi clearly observed, human beings went from building huts to building Saturn V rockets in a few thousand years. By any logical estimate made by reputable scientists, it will take less than one million years to colonize the whole galaxy. And the galaxy has been around for billions of years. The problem with this idea is that we have only one sample species - us. We can point to the fact that we went from huts to rockets in a few thousand years and say that it can happen that quickly, but that tells us nothing of how often it should happen. We might be on one end of a curve, and it may be the quick end. Other races might take millions of years to go from huts to rockets. Or, if we're in the middle of a curve, then most of the other races are too, and we can't expect to see their Saturn V rockets from lightyears away. Of, if we're on the slow end, what other forms of communication will be discovered in the next few centuries? If radio is just the passing fad of a few centuries then we should in no way be surprised that we don't hear others using it. The sticking point is like us. Why should we assume other intelligent life is like us? And SETI has said that we could only detect radio signals within about 100 light-years. That's a tiny fraction of the galaxy. If we just happen to be 100 light-years outside the galactic empire that controls all the rest of the galaxy we would have no way to tell, even if they were still using radio. I think the most sensible course of action is to state that we have no real evidence either way and be ready for either eventuality. Like I said earlier, if the day comes when we have colonized hundreds of other worlds and we still haven't found anyone else, then we might have a paradox.
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Post by Bill Thompson on Jul 19, 2007 2:22:17 GMT -4
Look, let's just look at the facts. As Fermi clearly observed, human beings went from building huts to building Saturn V rockets in a few thousand years. By any logical estimate made by reputable scientists, it will take less than one million years to colonize the whole galaxy. And the galaxy has been around for billions of years. The problem with this idea is that we have only one sample species - us. We can point to the fact that we went from huts to rockets in a few thousand years and say that it can happen that quickly, but that tells us nothing of how often it should happen. We might be on one end of a curve... Jason, it can be argued that no one in their right mind would call a species SLOWER than human beings "Intelligent". Once again we are talking about dogs and goats. And once again we are talking about waiting around billions of years, not a few thousand. So even if they are 100 times slower than us, they would still have had more than enough time to colonize the galaxy and we are back again to facing the fact that Fermi's observation is valid.
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Jason
Pluto
May all your hits be crits
Posts: 5,579
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Post by Jason on Jul 19, 2007 11:14:22 GMT -4
You seem to imply that intelligence is absolutely tied to technological progress. That is, if a species is more intelligent than humanity then it must develop things like radio and rockets faster than humanity did. How can we prove that this is the case?
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Post by Bill Thompson on Jul 19, 2007 18:53:21 GMT -4
You seem to imply that intelligence is absolutely tied to technological progress. That is, if a species is more intelligent than humanity then it must develop things like radio and rockets faster than humanity did. How can we prove that this is the case? Buy a puppy. You are not likely to find a better companion in the stars that is a good substitute for what you will fine at a pet store or the pound. As for an intelligent not inventing a radio.... That pretty much cuts them off from the rest of the universe and stops effective conversation and sending of data within their species. It does not sound very intelligent regardless of your definition. I find it hard to accept such a species would be worth finding. And, once again we are back to the tree falling in the woods. For all practical purposes, if they are impossible to see hear or detect, they are not there for practical purposes. We all want there to be ETI. It is an emotional issue since we are a species that hates to be alone. And that is how SETI traps us into supporting them and believing in them -- without intending to do so of course. Groups use ideas with strong emotional value to bypass critical thinking. Kathleen Taylor wrote a good book called "Brainwashing: The Science of Thought Control" where she describes how people do this. I am not saying that the SETI people intentionally brain wash people. But, at the same time, they are making the decision that there MUST be ETI out there because of the intense desire to believe in it. And they only look at the facts and figures that support it and interpret the data they want to and ignore information that does not support what they want to believe. What science tells us that ETI is unlikely and this view is increasing as we learn more and more. I suggest you find and read "Refuges for life in a hostile universe" published in Scientific American.
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