Alien life

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That wasn't made obvious. More than one person was confused by it his assertion. It has been cleared up now.
I suspect any confusion was that many think it would take 100,000 years at the speed of light to cross the Milky Way. My intent was to point out it takes much less time. 12 years to cross and I did later add 24 if you want to stop (and live). 12 years, 24 years or 100 years, the point was made.

D H also makes some good points about good manners in these forums. Unless you have the credentials of Einstein, Your opinion is just that, an opinion. Your presentation when disagreeing with some one says it all.
 
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Various estimates for how long it would take to colonize the galaxy range from 1 to 10 million years. Here are a couple in the middle of that range:
That's not what LURCH said, though. LURCH said,

If another civilization exists within this galaxy, it would have to be less than 1,000,000 yrs old, or they would have collonized Earth before we arose. This is a very narrow window, and makes it unlikely that such a civilization currently exists.
Emphasis mine. There is no compromise in that statement. There is no "perhaps," or any such verbiage in that statement. LURCH is stating unambiguously that there is a specific upper limit on the age of a civilization before they colonize the entire galaxy. This isn't even taking into account the fact that there is no guarantee a civilization would want to colonize the entire galaxy.

With so many moving parts, LURCH can in no way, shape or form state there is a "very narrow window." If LURCH had put in some ranges, add some qualifying statements, thrown in a heavy dose of uncertainty, I would have had no issue with the statement. But when phrased as an absolute, as if there were some hard cap as to how long a civilization can exist without colonizing the entire galaxy, I can't take it seriously.

Whoops, there I go appealing to ridicule.
 
Chronos
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It's a long way between stars and hugely expensive to explore. I doubt most rational civilizations would be willing to make the investment.
 
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When the Spanish royalty funded Columbus’ expedition, he didn’t have to create the National Seafaring Administration or hijack German scientists to create the technology for the ships or invent Velcro or Tang. Everything was already in place really and the expense was no more than any other maritime commercial venture of the time. So if Columbus hadn’t done it, then someone else eventually would have. I think that this ‘Columbus Paradigm’ applies to colonizing the universe too.
Eventually, the Earth will no longer provide enough living space for humanity. However, habitats in orbit can use energy from the Sun and resources from asteroids or the Moon to do this. As construction material improves, these self-sustaining habitats could eventually grow to the size of cities with populations of millions. The citizens of these habitats would then comfortably live out their lives in a microcosm. There would eventually be millions of these habitats in orbit around the Sun. Now add a fusion reactor for energy and a sail to any one of these, and then a solar powered laser could move the habitat to a nearby star at near the speed of light and the inhabitants would barely notice.
Our ancestors supposedly lived in trees and caves. Today we build our homes from wood and stone. In the future, we will build habitats in space that resemble our ancient home on Earth. We or a similar alien civilization would not need to colonize any other planet. Each star system would provide energy and most likely building material to sustain growth by construction of habitats in space. A species that colonizes a galaxy most likely won’t stop there. There are millions of galaxies within migration distance of the Earth, but not one single contact.
So this is my speculation on the Fermi Paradox.
 
D H
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That's not what LURCH said, though. LURCH said [some rather strong statements]. There is no compromise in that statement. There is no "perhaps," or any such verbiage in that statement. LURCH is stating unambiguously that there is a specific upper limit on the age of a civilization before they colonize the entire galaxy. This isn't even taking into account the fact that there is no guarantee a civilization would want to colonize the entire galaxy.
LURCH was quite emphatic in what he said. You could have pointed this out and asked for a justification for the statements he made in his post. That would have been a perfectly valid response.

That is not what you did. You instead argued with invective and with logical fallacies. Logical fallacies are not an acceptable form of argument here at PF, and invective is not an acceptable form of discussion. Some advice: Tone down your rhetoric and steer clear of fallacies. By doing so you will be taken much more seriously and you will avoid jumping on the ban wagon.
 
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...Eventually, the Earth will no longer provide enough living space for humanity...
Scientist say we are already using 30% more resources then the Earth can sustain and by 2050 it will take two Earths. Most seem oblivious to the obvious out come in their children's future. Despite all the marvelous things humans have accomplished, it seems we may not have the "Right Stuff" to not become eventually extinct. Now consider nuclear war, meteors, etc...
 
D H
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Scientist say we are already using 30% more resources then the Earth can sustain and by 2050 it will take two Earths.
Reference, please.
 
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Reference, please.
I believe it was the History channel where I first heard it but a Google search will find more articles then you can count. I am not sure who is the most reputable source but for starters.

http://www.redorbit.com/news/science/1594776/reckless_consumption_depleting_earths_natural_resources/index.html
"If our demands on the planet continue to increase at the same rate, by the mid-2030s we would need the equivalent of two planets to maintain our lifestyles," said WWF International Director-General James Leape.

Another interesting link to information is the world population clock.
http://www.peterrussell.com/Odds/WorldClock.php
The population of the planet is increasing by over 200,000 people per day. Every one of those people will require food and energy to survive. The food clock link on that web site is interesting also. You will not believe how may chickens we consume every day.

I read in the news often about the oceans being depleted of fish, the rain forest shrinking and oil consumption is outrageous. As the forest shrink, the deserts grow and there are more people to fit in the equation. Climate change (natural or man made) will be devastating to the human race if we make it that far.

I would think that those participating in these forums would be most likely to be on top if this type of information and the last to stick their head in the sand. Technology is moving very fast to solve problems but I don't think fast enough. I better get back to work on my dooms day machine. :smile:
 
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The possibility that we don’t survive to find alien life is of course reasonably real. However, I might caution that those 200,000 people born each day could develop skills or discover new skills that they would trade for food and energy, the way I do, to survive. The efficient use of our planet’s, and solar system’s abundant resources could support several million times the Earth’s current population for geological time periods. A single 10-mile wide nickel-iron asteroid has more ore than has been mined on Earth in all of history. Space habitats can collect vast amounts of virtually free energy from the Sun for eons. If we took the money they want to spend to save the planet (from our species) and used it to remove our species to NEO, then we certainly could all live in space habitats within a century. Most of the technology already exists to make this possible. Once we secure our survivability, then it’s just a matter of time before we find alien life.
 
D H
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http://www.redorbit.com/news/science/1594776/reckless_consumption_depleting_earths_natural_resources/index.html
"If our demands on the planet continue to increase at the same rate, by the mid-2030s we would need the equivalent of two planets to maintain our lifestyles," said WWF International Director-General James Leape.
In short, environmental alarmism. Think about it this way. We are not yet a Type I civilization; we're not even close. World-wide energy consumption is 16 terawatts, a paltry 0.01% of the 174 petawatts of energy the Earth currently receives from the Sun. The WWF has pulled a page out of Enron's playbook -- creative accounting. The number in question is the WWF's "Environmental Footprint", defined as the ratio of WWF's accounting of "humanity’s demand on the biosphere" to the Earth's biocapacity (both expressed in area). The demand side assesses "the area of biologically productive land and sea required to provide the resources we use and to absorb our waste." The WWF attributes a demand of 0.6 Earths to offset the burning of petrochemicals.
 
LURCH
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Wow, I need to check in on these threads more often! All I did was re-state the Fermi Paradox. I noticed that some in this thread were referring to it, so I thought it (or a summary of it) should be included within the thread content. Didn't think it would stir up such a hornet's nest. However, I did make some statements without my usual blizzard of qualifiers, and for that I apologize.

First, some other points that have come up;
I suspect any confusion was that many think it would take 100,000 years at the speed of light to cross the Milky Way. My intent was to point out it takes much less time. 12 years to cross and I did later add 24 if you want to stop (and live). 12 years, 24 years or 100 years, the point was made.
Although that statement is completely valid, I think that the reference frame of those observers not inside the vehicle is the one most pertinent to the current discussion. The absence of ET's in our backyard is a puzzle that relates to how much time it takes them to get here in our reference frame, not theirs, don't you think?

When the Spanish royalty funded Columbus’ expedition, he didn’t have to create the National Seafaring Administration or hijack German scientists to create the technology for the ships or invent Velcro or Tang. Everything was already in place really and the expense was no more than any other maritime commercial venture of the time. So if Columbus hadn’t done it, then someone else eventually would have. I think that this ‘Columbus Paradigm’ applies to colonizing the universe too.
Eventually, the Earth will no longer provide enough living space for humanity. However, habitats in orbit can use energy from the Sun and resources from asteroids or the Moon to do this. As construction material improves, these self-sustaining habitats could eventually grow to the size of cities with populations of millions. The citizens of these habitats would then comfortably live out their lives in a microcosm. There would eventually be millions of these habitats in orbit around the Sun. Now add a fusion reactor for energy and a sail to any one of these, and then a solar powered laser could move the habitat to a nearby star at near the speed of light and the inhabitants would barely notice.
Although I see your position, I think it is built on the assumption that outward migration would be driven by necessity, and civilizations would only move on when all local resources are exhausted. I believe this assumption to be false. There is no known example of a life-form that stays where it is untill forced to move. AFAIK, all species expand their range whenever they can, not when they have to.
Later in that same post;
...A species that colonizes a galaxy most likely won’t stop there. There are millions of galaxies within migration distance of the Earth, but not one single contact.
So this is my speculation on the Fermi Paradox.
I don't know as I agree with this statement, although it depends entirely on what one considers "within migration distance." The Large and Small Magilanic Clouds are about 200,000 ly away, and aside from them, it's all dwarf galaxies untill Bernard's, which is more than a million and a half. To me, this makes traveling around one's own galaxy sound like an entirely different animal from intergalactic travel. A race that has the tech to go star-hopping over distances of 10 to 100 ly is still a long way from having the juice to go a million ly from one galaxy to another.

As for "...no guarantee a civilization would want to colonize the entire galaxy..." I can only repeat that there is no species in existance that does not expand its range whenever possible. According to all availabel data, life continues to spread out untill it reaches a barrier it cannot surmount.
 
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I was simply showing that every ocean-going vessel in Columbus’ age could make the voyage to the New World and that similarly every space habitat would by design be capable of an interstellar voyage.
I’ve read that there are millions of galaxies within a one billion LY radius of our galaxy. At .1c that would make them within range of migaration if the civilization became spacefaring 10 billion years ago. Just speculating.
 
Nabeshin
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I was simply showing that every ocean-going vessel in Columbus’ age could make the voyage to the New World and that similarly every space habitat would by design be capable of an interstellar voyage.
I’ve read that there are millions of galaxies within a one billion LY radius of our galaxy. At .1c that would make them within range of migaration if the civilization became spacefaring 10 billion years ago. Just speculating.
Columbus' voyage was funded because the European royalty knew they would get results when he returned, in a year or so (my historical knowledge is not amazing, but you get the idea). No communication would even be possible with the home planet for decades, for the nearest stars.
 
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No instant communication would be necessary. Millions of people living for generations in a habitat community might not even remember their "home world". They would decide to go to the next star system for any number of reasons.
 
D H
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I was simply showing that every ocean-going vessel in Columbus’ age could make the voyage to the New World and that similarly every space habitat would by design be capable of an interstellar voyage.
The immense differences in scale in cost and time do not justify this false analogy. You assumed a lot of potentially false items:

Eventually, the Earth will no longer provide enough living space for humanity. However, habitats in orbit can use energy from the Sun and resources from asteroids or the Moon to do this. As construction material improves, these self-sustaining habitats could eventually grow to the size of cities with populations of millions. The citizens of these habitats would then comfortably live out their lives in a microcosm. There would eventually be millions of these habitats in orbit around the Sun.
I'll grant you all of this for the sake of argument. Now, first question: Where is the impetus to move on? The sun puts out a lot of energy and the solar system has lots of resources in the form of entire asteroids and lifeless planets to be plundered. Our descendants will have to begin depleting the resources of the solar system before the same kinds of population pressures that forced us to leave the planet make us consider leaving the solar system.

Now add a fusion reactor for energy and a sail to any one of these, and then a solar powered laser could move the habitat to a nearby star at near the speed of light and the inhabitants would barely notice.
Too much handwaving! How many inhabitants on the vehicle? Do the math. You are talking about an exawatt laser, firing continuously for a long time. Now the vehicle gets to the star. How will it slow down? (The target star is presumably void of civilization and thus does not have an exawatt laser on hand.)
 
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In short, environmental alarmism...
Let me guess, republican. I usually vote conservative but that is just so I can keep my guns so I will be able to get food when things go down. :smile:

Lets say the "environmental alarmist" are 90% wrong. Then it would be your kids kids rather then you kids that endure the issues. Or do you believe we can continue reproducing like we are forever with out problems from it? Do the pictures from space showing the desserts expanding and the forest getting smaller concern you at all?
 
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Although that statement is completely valid, I think that the reference frame of those observers not inside the vehicle is the one most pertinent to the current discussion. The absence of ET's in our backyard is a puzzle that relates to how much time it takes them to get here in our reference frame, not theirs, don't you think?
Not at all. It is just that things are taken out of context when read out of order.

In post #9 yenchin said:
" Space travel is not just about exploration though, it is essential for survival of any advanced species if they were to live pass the life time of their star. When the Sun goes into red giant stage, we had better have somewhere else to go by then (although one can just get into a space colony of some sort without travelling too far I supposed...)"

My first post concerning quick travel accross the Milky Way in post #14:
"A 1G continuous acceleration rocket could take us from one edge of the Milky Way to the other in just 12 years travel time. Our likely destination would most likely be much less distance. Earth time may be many thousands of years but who cares if it is dying. It would be a one way trip to save the human race. "

Now it seems to make a lot of sense Don't you think?
 
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I was simply showing that every ocean-going vessel in Columbus’ age could make the voyage to the New World and that similarly every space habitat would by design be capable of an interstellar voyage.
I agree, There was a time when crossing the Atlantic was impossible. I am sure there were many folks back then thinking just like many in this forum are thinking now. It won't be that hard to do with the know how and equipment just like space flight is routine now. My parents would have laughed at anyone talking about space travel when they were young.
 
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http://science.nasa.gov/headlines/y2008/31jul_solarsails.htm [Broken]
"Solar sailing is the only means known to achieve practical interstellar flight,"
http://www.niac.usra.edu/files/studies/final_report/333Christensen.pdf
http://science.nasa.gov/newhome/headlines/prop08apr99_1.htm [Broken]
http://aerospace.wcc.hawaii.edu/sail.html [Broken]
Etc.
Sorry if I skipped over too much. I didn’t want to hijack the thread discussing really basic stuff. The problem of interstellar flight is that not only must the fuel accelerate the mass of the craft, but the fuel must accelerate the mass of the rest of the fuel as well. I read in a book where someone had done the math that to send a 10 ton craft to the next star would take several thousand tons of antimatter and a similar mass of matter. A solar sail uses light “pressure” to move through space and doesn’t carry its fuel. The light would come from an enormous orbital laser that receives virtually endless energy from the Sun and then aims a beam at the sail. By angling the sail to create drag the ship can be slowed. Interstellar travel is possible and a species that colonizes a galaxy will find a way to get to the next galaxy. As I mentioned, there are lots of reasons for people like me or aliens to go to other stars and galaxies. My ancestors came from Europe. I’ve never missed their ‘home continent’ and I sadly don’t communicate with any distant relatives there.
 
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D H
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http://science.nasa.gov/headlines/y2008/31jul_solarsails.htm [Broken]
"Solar sailing is the only means known to achieve practical interstellar flight,"
Please. That is a quote from a solar sail fanatic. This ignores work (much more successful work) done in the realm of advanced propulsion techniques, and ignores other even more fanciful techniques (e.g., Bussard ramjets) that, like solar sails, are presently solidly in the realm of science fiction. From the same article, "To date, no solar sail has been successfully deployed in space as a primary means of propulsion."

Using a solar sail to launch a tiny unmanned probe to another star is science fiction but may well become science fact. Using a solar sail to launch a huge colonization spacecraft to another star is science fantasy.
 
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LURCH
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Not at all. It is just that things are taken out of context when read out of order.

In post #9 yenchin said:
" Space travel is not just about exploration though, it is essential for survival of any advanced species if they were to live pass the life time of their star. When the Sun goes into red giant stage, we had better have somewhere else to go by then (although one can just get into a space colony of some sort without travelling too far I supposed...)"

My first post concerning quick travel accross the Milky Way in post #14:
"A 1G continuous acceleration rocket could take us from one edge of the Milky Way to the other in just 12 years travel time. Our likely destination would most likely be much less distance. Earth time may be many thousands of years but who cares if it is dying. It would be a one way trip to save the human race. "

Now it seems to make a lot of sense Don't you think?
Ah yes, now I follow you. Certainly the duration of the trip as experienced by those onboard the vehicle would be a significant factor regarding the decission to go or not.
 
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Do you mean to tell me a species is going to travel 1000, 5000, 10,000, or 50,000 light years across the galaxy to live on our modest planet?

What do you think we would do if we found a livable planet and had the means to get there?

I have no doubt we would colonize it. Why should an alien race be any different?
 
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What do you think we would do if we found a livable planet and had the means to get there?

I have no doubt we would colonize it. Why should an alien race be any different?
My point was there is an immense number of worlds, and turning any of those into a livable planet seems more efficient than traveling halfway across the galaxy. Even if we had the means to get there, I'm having trouble imagining a time where the expense to do it would be anywhere near trivial.

Also, why might an alien race be different? Well, because they're an alien race.

Sorry, circular argument, logical fallacies don't fly here, right?

An alien race would most likely have grown up in an entirely different environment than we have on Earth. There's no guarantee that the same chemicals and temperatures we find necessary for life would work for them. If we can't even get into alien biology, there's simply no way we can even begin to look at alien psychology, in my opinion.

This all started when LURCH failed to put in any kind of qualifiers to his "1,000,000 year upper limit" to a civilization before they colonize everything. With so many unknowns, I wouldn't be comfortable guessing at such a thing with a range smaller than 3 orders of magnitude.

I apologize for my abrasive tone earlier. Seeing exact numbers (such as the Drake Equation "solution,") where ranges spanning many orders of magnitude should be threw me off a bit.
 
D H
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My point was there is an immense number of worlds, and turning any of those into a livable planet seems more efficient than traveling halfway across the galaxy. Even if we had the means to get there, I'm having trouble imagining a time where the expense to do it would be anywhere near trivial.
Please stop using straw men. Nobody is saying that species would travel halfway across the galaxy to get here. That is a mischaracterization of the colonization argument. The colonization arguments says that an space-faring species would colonize every available planet in the galaxy in a fairly short period of time (10 million years constituting a short period of time compared to the age of the universe).

So, why hasn't this happened? There are after all several valid arguments against the Fermi paradox. Here are but a few:
  • Colonization is sporadic. A colony set up by a space-faring species will be on its own. Some colonies will die, some will stay contended in their new home. This is the percolation argument. http://www.geoffreylandis.com/percolation.htp

  • Space colonization is essentially impossible. Space travel even amongst the planets is presently an extremely expensive proposition. Even if a species does manage to expand beyond the bounds of its home planet, expanding beyond the bounds of its home star system may well be forever out of reach. http://www.antipope.org/charlie/blog-static/2007/06/the_high_frontier_redux.html

  • Intelligent species don't last long enough to take the first step. They self-destruct.

  • Intelligent species are so incredibly rare that we are for all practical purposes all alone. Stephen Webb, If the Universe Is Teeming with Aliens... Where Is Everybody? Fifty Solutions to Fermi's Paradox and the Problem of Extraterrestrial Life, Springer (2002). Webb provides 50 solutions to the Fermi paradox in this book. This is solution #50, and is his preferred solution.
 
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Please stop using straw men. Nobody is saying that species would travel halfway across the galaxy to get here.
D H:

I was responding a specific post by BoomBoom saying that we would travel to a habitable planet if we had the means to get there. I said that we might not, because even if we had the means to get there, we'd likely also have the means to make a lot of easier steps. In that part of the post, I was not responding to aliens coming here, I was responding to the human species going elsewhere, and more specifically, the human species as it stands right now on Earth.

So, now who's using the straw man?
 

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