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UFO/ET… How sceptic are you ?
Posted: 20 October 2010 07:40 PM   [ Ignore ]   [ # 31 ]
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DarronS, is it then? I always thought of the Milky Way as being not particularly large for a galaxy! Ah well!! back to the books!! smile

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Posted: 20 October 2010 07:54 PM   [ Ignore ]   [ # 32 ]
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That’s what we are taught growing up. We are also taught our Sun is an average star, when it most certainly is not. One of the major issues I see in the philosophy of science is that scientists keep insisting we do not occupy a special place in the Universe, but a little inquiry reveals this is false. We live at a time when we can see both the slowing and acceleration of the Universe’s expansion. We live in a rare stellar system around an apparently even more rare planet which is, briefly, capable of supporting not only complex life but has the energy resources available to allow one rare species on that planet the free time to ponder how and why the Universe exists as it does. We could very well be the only advanced civilization in our galaxy.

With one hundred billion other galaxies in the observable Universe the odds are overwhelmingly in favor of other advanced civilizations existing in the Universe, but the odds are also overwhelmingly against us contacting any of those civilizations.

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Posted: 20 October 2010 08:12 PM   [ Ignore ]   [ # 33 ]
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DarronS - 20 October 2010 07:54 PM

With one hundred billion other galaxies in the observable Universe the odds are overwhelmingly in favor of other advanced civilizations existing in the Universe, but the odds are also overwhelmingly against us contacting any of those civilizations.

We are certainly in agreement there!!

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Posted: 20 October 2010 09:01 PM   [ Ignore ]   [ # 34 ]
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DarronS - 20 October 2010 07:54 PM

We live in a rare stellar system around an apparently even more rare planet

How do we know our planet is rare?

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Posted: 20 October 2010 09:06 PM   [ Ignore ]   [ # 35 ]
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See post #24 in this thread, George.

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Posted: 20 October 2010 11:18 PM   [ Ignore ]   [ # 36 ]
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Personally, I think we’re asking the wrong questions here. The real question lies in whether Zeus, Vishnu, or the Leprechauns created the UFO’s.

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Posted: 21 October 2010 02:40 AM   [ Ignore ]   [ # 37 ]
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Now, now. I do not believe in leprechauns

And I very much suspect that they do not believe in me either.

It may well be true that there are only, perhaps, 70 or fewer planets in our galaxy where advanced civilizations could have ORIGINATED. That’s not the same as saying there are only 70 or so planets where advanced civilizations MIGHT CURRENTLY EXIST. Colonization, even of planets that are too short-lived, or that have environments not conducive for complex life-forms to have evolved, may well be common throughout the galaxy.

I suggested that interstellar propulsion systems might exist that we don’t yet know about. To infer from this suggestion that, therefore, we KNOW that alien spacecraft must use them, is a logical fallacy of monumental proportions. They MIGHT exist. Other advanced civilizations MIGHT use them. We don’t KNOW, one way or the other.

I agree that the Phoenix lights were most probably flares.

We should, however, keep our minds open to possibilities that presently seem outlandish - unlike Lord Kelvin who proved, to his own satisfaction at least, that heavier-than-air flying machines were impossible.

Perhaps the aliens, if they exist, don’t give much weight to the economic imperatives that seem so important to us humans. From our economic perspective, interstellar travel may well be a losing proposition. Perhaps our hypothetical aliens have quite different motivations.

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Posted: 21 October 2010 04:33 AM   [ Ignore ]   [ # 38 ]
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Return on investment is not about motivation, it is about sustainability. Any society that continually depletes its resources faster than it can replace them will collapse.

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Posted: 21 October 2010 06:34 AM   [ Ignore ]   [ # 39 ]
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DarronS - 20 October 2010 09:06 PM

See post #24 in this thread, George.

The only thing in reference to the “right” planet you say in that post is that one needs a “planet of the right size in the right place, [with] right chemical mix on the planet.” I still don’t see how you derived that such planets are rare.

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Posted: 21 October 2010 06:41 AM   [ Ignore ]   [ # 40 ]
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Apparently you missed the parts about red dwarf stars being to unstable to support complex life, stars lager than our Sun being too hot and too short-lived to enable complex life to develop, and, most stars, even Type G stars, existing in binary systems which makes them unsuitable for complex life to develop. I also mentioned that for complex life to develop a stellar system will need a gas giant planet outside the orbit of the rocky planet in the habitable zone to protect that planet from incoming comets and asteroids. If you need further evidence look at Venus and Mars.

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Posted: 21 October 2010 07:56 AM   [ Ignore ]   [ # 41 ]
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Right, I agree with you on the stars. When it comes to planets, however, I really don’t think we know enough to conclude that planets like ours are rare. They could be, the could be not.

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Posted: 21 October 2010 08:34 AM   [ Ignore ]   [ # 42 ]
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DarronS - 21 October 2010 06:41 AM

Apparently you missed the parts about red dwarf stars being to unstable to support complex life, stars lager than our Sun being too hot and too short-lived to enable complex life to develop, and, most stars, even Type G stars, existing in binary systems which makes them unsuitable for complex life to develop. I also mentioned that for complex life to develop a stellar system will need a gas giant planet outside the orbit of the rocky planet in the habitable zone to protect that planet from incoming comets and asteroids. If you need further evidence look at Venus and Mars.

All true.  But the immense size of the Universe could easily accommodate many, many Goldilocks planets with life-saving asteroid-vacuum gas giants nearby.  The same thing proponents of the UFOs-are-visiting-alien hypothesis don’t understand—the incredible vastness and size of space—is the one thing that could make life-friendly planets abundant.  Granted, if there are any, they are never coming here and we are never going there.  The Universe is too big and the space in between is too far away.  But it is that same size that keeps us apart is the same thing that could provide more than enough room for other life-bearing planets to form.  We know it happened once, so it is not impossible.  Improbable?  Perhaps.  But clearly not impossible.  It can be done because it has been done…at least once.

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Posted: 21 October 2010 10:08 AM   [ Ignore ]   [ # 43 ]
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George, you are right, we don’t have enough data to draw definite conclusions, but considering all the coincidences necessary for a planet to support complex life the reasonable conclusion is planets like ours are exceedingly rare. What are the odds of a Mars size asteroid hitting an Earth size planet early in the solar system’s history and forming a moon that causes tides? There is no physical law that states an Earth size planet has to exist at about the same distance from a star as we are from the Sun. We know very little about solar system formation, and admittedly what I have proposed is mere speculation. It seems most of us agree that even if there are other advanced civilizations in our galaxy the chances of contact are nil.

Looking at that last sentence, I see another issue. We keep using the present tense when discussing the possibility of alien civilizations, but the odds of such a civilization existing in the same time as ours are just as long as the odds of a suitable solar system for other civilizations to arise. As I mentioned earlier, if intelligence does evolve around another star the civilization could rise and fall millions of years before our ancestors were walking the savannas. Plus, there is no guarantee that intelligence will evolve even on a suitable planet. Of all the millions of species that have evolved, lived and died out on this planet only one has been capable of leaving the planet.

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Posted: 21 October 2010 12:00 PM   [ Ignore ]   [ # 44 ]
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dougsmith - 05 August 2010 04:30 AM

I should add that while it is against the laws of physics to travel faster than light, and to do many of the things one finds on shows like Star Trek, it is not strictly speaking against any physical laws to build multi-generational ships that could travel between the stars. There would be formidable obstacles to doing so, and they would be prohibitively expensive at this point, but I don’t see anything that would make them literally impossible.

You’re also assuming that “multi-generational” pertains to life spans somewhat similar to ours.  If some beings have developed their medical technology to the point that living 10,000 years is normal, interstellar travel is certainly viable within one lifetime.

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Posted: 21 October 2010 03:02 PM   [ Ignore ]   [ # 45 ]
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asanta - 20 October 2010 07:02 PM

Mind boggingly huge is an apt description! Another thing to note…our galaxy isn’t even a very large one!

100,000 light years in diameter.  We are about 30,000 light years from the center.

@DarronS - Is there any kind of chart with the number of stars within a given radius of Earth.  Like how many within 10 LY, within 20 LY, 30 LY, etc, etc.

I like the idea of building the starship into an asteroid.  Create spaces by hollowing out a nickle-iron asteroid.  Process the dug out matter to produce as many components as possible.  Check out Rite of Passage by Alexi Panshin.  Assume the aliens have some propulsion system that can get that mass to 20% of C.  We will probably have life extension techniques within the next 200 years even if it is only based on genetic engineering so assume 300 year life spans.  Add to that some kind of cold sleep to reduce boredom and drain on consumables. 

http://www.lunch.com/Reviews/book/Rite_of_Passage-1631905.html?cid=121&rid=21748#rid_21748

So a 20 light-year voyage would take 100 years and the crew ccould sleep 2/3rds of that in shifts so they only age 33 years.  That doesn’t sound like a bad deal with a 300 year life span.  So presumably a civilization capable of doing this would send von Neumann probes to find places worth sending live crews to.  But if modulated radio waves are detected from someplace that would attract attention.  We have been transmitting for close to 100 years.  Has anyone ever computed at what distance we could detect ourselves with our current technology?

psik

[ Edited: 21 October 2010 03:08 PM by psikeyhackr ]
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