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Old 11-28-2004, 04:55 PM
ricksummon ricksummon is offline
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Fermi's Paradox: Could We Detect Ourselves?

Fermi's Paradox is often used to argue against the existence of intelligent life elsewhere in the galaxy by stating "If they're out there, why can't we detect any sign of them?" But how easy would it be to detect "them"? If a civilization existed on a planet 20 light-years away from Earth with exactly the same technological level as Earth today, would they be able to detect radio signals indicating intelligent life on Earth?
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  #2  
Old 11-28-2004, 05:03 PM
Mr. Kobayashi Mr. Kobayashi is offline
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Surrounding the Earth is an expanding sphere of radio waves, now over 60 light years in radius, the product of transmissions from radio and TV stations. These could be detected by an advanced extraterrestrial intelligence, who might then send back a signal to us as a means of exchanging a greeting.
http://www.phys.unsw.edu.au/hsc/cosmic_contact.html

So a planet 60 light-years from earth would pick up our first radio broadcasts. The nearest star, Proxima Centauri, is 4.3 light-years away, for comparison.
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Old 11-28-2004, 05:04 PM
Q.E.D. Q.E.D. is offline
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Nope. We don't have the technology to detect radio signals at the level of our current incidental broadcast radio and television emissions. However, we could detect an intentional transmission from something like an Arecibo-class radiotelescope, if it were aimed at us and we were listening at the right moment.
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Old 11-28-2004, 05:18 PM
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Actually, Fermi's paradox doesn't have much to do with SETI. Fermi's paradox says that if there were advanced life out there, they should have colonized the galaxy by now, including our very habitable planet.

It's based on the observation that civilization and technology advance so quickly, compared to the billions of years of evolution it took to get intelligent life capable of advanced technology, that the odds of us and someone else developing in parallel, before one of us could colonize the whole galaxy, is basically nil.
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Old 11-28-2004, 05:41 PM
Loopydude Loopydude is offline
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Along the lines of what bup said, there was an interesting article in SciAm a while ago, in which the authors attampted to show how a hypothetical advanced civilization, using only sub-light-speed propulsion, could colonize the Milky Way in a couple million years. This is approx. 0.02% the life-span of the galaxy itself. So, to put it in perspective, if the age of the Milky Way was one day, this advanced civilization would have colonized all inhabitable worlds in about 15-20 seconds. Obviously, there are a lot of assumptions built into this scenerio, but it gets at the crux of the Fermi Paradox: Unless we're the first advanced civilization to evolve in the Galazy, it's hard to explain why we wouldn't have met up with the descendants of another advanced civilization by now, since in terms of galactic lifespans, it takes but a moment to spread throughout the entire galactic disk.
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Old 11-28-2004, 06:14 PM
toadspittle toadspittle is offline
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Originally Posted by Loopydude
Unless we're the first advanced civilization to evolve in the Galazy, it's hard to explain why we wouldn't have met up with the descendants of another advanced civilization by now, since in terms of galactic lifespans, it takes but a moment to spread throughout the entire galactic disk.
Actually, that's only one of the solutions (we're the first advanced civilization) to the paradox. There could also be a galactic quarantine on us underdeveloped critters (a la the prime directive), or it may be impossible for a civilization to survive its own coming of age (we tend to blow ourselves up).

[I think there are others, but I don't recall them.]
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Old 11-28-2004, 06:19 PM
Loopydude Loopydude is offline
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I think your first alternative falls prey to the human analogy: Would we not make contact, if given the opportunity? I guess some folks think we'll never have the wisdom to follow a Prime Directive. I wonder why.

As for your second alternative: Depressing, but all too likely.
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Old 11-28-2004, 06:27 PM
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Off the top of my head, it could be that we're the first with our particular sort of biochemistry, or the first with an urge to exploration, or some combination, so the rest are uninterested in our planet. It could be that they have visited us, and we just don't know it yet (shades of Chariots of the Gods, here, but it can't be ruled out). It could be that they do visit here on a regular basis, but that regular basis is once every ten thousand years or so. It could be that once a civilization develops technologically enough that they can colonize the Galaxy, technology has also made them essentially independent of planets. It could be that an entire galactic empire did rise, but then fell a few billion years before we arrived on the scene (this could even serve to synchronize the development of post-Empire civilizations). There are a lot of possible explanations, but it does seem a bit odd.
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Old 11-28-2004, 06:33 PM
Bytegeist Bytegeist is offline
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Originally Posted by ricksummon
Fermi's Paradox is often used to argue against the existence of intelligent life elsewhere in the galaxy by stating "If they're out there, why can't we detect any sign of them?"
Actually I think Fermi was speculating: if there's other intelligent life in our galaxy, why aren't they already here? As in physically, right here, in some form or another.

His argument was that a technological species should be able to populate, or at least explore with probes, the entire Milky Way galaxy within a "short" length of time, once they had gone a little past our level of technology. In this context, "short" means maybe a million years give or take — an enormous time-span in ordinary human experience of course, but hardly anything at all in astronomical time. If you ignore issues about the aliens' economics, psychology, and possible motives for such a project, which are hard to know of course, it's at least physically possible to visit every star system in the galaxy in that time frame. And the aliens could do it even assuming they're constrained by the speed of light, which as far as we can tell, we all are.

Since there has been plenty of time for the Milky Way to churn out species of our level of intelligence and technology, and to have done so a billion years before our ancestors could even walk on two legs, Fermi asked the question, "Where are they?" As in, shouldn't the aliens already be here by now? At least one species, if not a hundred of them, many times over? But since they aren't here, and haven't been here, that bodes ill for the prospect of aliens. They probably don't exist. We are either alone in this galaxy, or at least functionally alone for all practical purposes.

(On preview I see that bup and Loopydude have beaten me to my points, and that Chronos has supplied most of the retorts I was going to offer. Ah well, better leave off here. But let me recommend Achenbach's Captured by Aliens as a good book to read for anyone interested in this subject.)
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Old 11-28-2004, 08:47 PM
Loopydude Loopydude is offline
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Originally Posted by Chronos
...shades of Chariots of the Gods, here, but it can't be ruled out...
They could even be here right now, living among us, in disguise!

Oh well. I guess that would have occurred to a mind as brilliant as Fermi's, and I don't doubt he'd have a clever retort, along the lines of "Why bother?" When I first encountered Fermi's paradox, I must admit my heart sank a little.
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Old 11-28-2004, 09:32 PM
asterion asterion is offline
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Quote:
Originally Posted by toadspittle
Actually, that's only one of the solutions (we're the first advanced civilization) to the paradox. There could also be a galactic quarantine on us underdeveloped critters (a la the prime directive), or it may be impossible for a civilization to survive its own coming of age (we tend to blow ourselves up).

[I think there are others, but I don't recall them.]
Or a civilization becomes more and more technological to the point where life basically no longers exists in our universe but in a sort-of online universe. That's a bad description of the idea, but I've seen it in several science fiction short stories.
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Old 11-29-2004, 12:08 AM
ralph124c ralph124c is offline
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Civilizations That urn Inward?

Suppose that as intelligence evolves, these speices become less and less interested in colonizing space..would these civilizations ever be detected? Take our own planet..we may well stop using AM radio very soon, and most of our TV now is delivered by fiber-optic cable. So our own emissions of RF information may well cease (to the point where they would be undetectable outside the solar system). We may also find that genetic research and improving our lives is more interestng than exploring outer space. All this talk about a "galactic civilization"..unless Einstein was wrong..I don't see it happeneing. It would take centuries to get to the nearest inhabitable star-planet systems, and humans don't live long enough to attempt this.
Of course, if we could perfect "coldsleep"..we might have something!
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Old 11-29-2004, 06:17 AM
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Lucky for Arsenal, then!

Perhaps the first we will know of alien civilisations is when they build a hyper-space bypass, blowing up Earth in the process...
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Old 11-29-2004, 07:15 AM
wevets wevets is offline
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Originally Posted by toadspittle
[I think there are others, but I don't recall them.]
Perhaps another is that advanced civilizations exist, and have the ability to spread themselves throughout the galaxy using sub-light speed methods, but don't have the incentive to?

I know that even if one existed, I wouldn't make any plans to step on an interstellar colony ship just so my great-great-great grandkids could land and terraform some distant planet. I like it here too much.
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Old 11-29-2004, 07:22 AM
Mangetout Mangetout is offline
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Other possibilities:

Individual planets do not typically contain sufficient resources to jump-start a galactic civilisation (or they do, but technological societies always deplete the resources too far before they attain the (doubtful)technologies for insterstellar travel)
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Old 11-29-2004, 07:48 AM
SentientMeat SentientMeat is offline
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SETI tells us that nobody within 5 light years (see map) is broadcasting TV or radio, nobody within 50 light years (map) is using military radar, and nobody in this galaxy ever swept the skies occasionally with a high frequency gigawatt beam (eg. Arecibo) just to see if anyone sent anything back. So, at 20 light years I believe they could detect military radar (but not TV or radio) having "structure", and could certainly detect the deliberate high powered emissions (which we haven't bothered with for some years, I believe).

Now, this does not necessarily mean that there is nobody there, but the alternatives are all unlikely for one reason or another:
  • There might be a ruthlessly enforced galactic silence policy, and nobody uses electromagnetic signals any more. However, each such civilisation could still not prevent the leaks from their technological infancy, and it is difficult to believe that nobody, not even a malfunctioning piece of equipment or a mischievous joker, ever lets slip an electromagnetic signal detectable by the incredibly sensitive receptors on Earth.
  • The aliens might have encased this planet in a “shield” impermeable to transmissions. Unfortunately, this would require such enormous resources and manipulation of spacetime that we might as well suppose that they are keeping us in the Matrix.
  • Perfect compression is indistinguishable from noise (ie. a signal which has been coded for optimum efficiency simply sounds like a detuned radio). This is a genuine possibility. However, again, there must surely be some leaks from way back when the coding was imperfect, and it would seem imprudent to code eg. emergency beacons so that they couldn’t be identified.

So, it is still possible they are out there in this galaxy. However, there are two definite facts:
  • The technology required to emit a galaxy-wide audible signal is only as advanced as that required to make a nuclear weapon.
  • We appear to be the only ones ever to have done so.
One wonders whether the two facts are related.
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Old 11-29-2004, 07:57 AM
tim314 tim314 is offline
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I think it's a bit much to expect any civilization (including our own) to embark on an exploration project that would take millions of years to complete, given a lifespan of only about a hundred years. Who's to say there'd be anyone waiting for the explorers when they came back? And if they're not planning on coming back, then there's all the less reason to send them in the first place. Does it really satisfy our desire to explore just to know that there's some human who's seen the other side of the galaxy up close -- even if they never come back and tell us about it? When in human history has anyone ever financed a one-way mission of exploration? (Meaning one that was deliberately one-way, not just one that happened to work out like that.)

And as far as galactic civilizations, is there really that much incentive to expand beyond the point where we can even communicate with each other? If we extend ourselves more than 100 lightyears out, it would take a lifetime just to call home.
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Old 11-29-2004, 08:43 AM
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Originally Posted by tim314
I think it's a bit much to expect any civilization (including our own) to embark on an exploration project that would take millions of years to complete, given a lifespan of only about a hundred years. Who's to say there'd be anyone waiting for the explorers when they came back? And if they're not planning on coming back, then there's all the less reason to send them in the first place. Does it really satisfy our desire to explore just to know that there's some human who's seen the other side of the galaxy up close -- even if they never come back and tell us about it? When in human history has anyone ever financed a one-way mission of exploration? (Meaning one that was deliberately one-way, not just one that happened to work out like that.)

And as far as galactic civilizations, is there really that much incentive to expand beyond the point where we can even communicate with each other? If we extend ourselves more than 100 lightyears out, it would take a lifetime just to call home.
The most compelling reason to colonize is that a star won't last forever. Would a civilization rather die violently than try to reach the next star?

However, that is one resolution of the Fermi paradox - interstellar travel is too close to impossible, or the emotional barriers make it just too sucky.

Another way around colonization, which I've mentioned before on these boards, is the idea of building our own star out of local brown dwarves rather than trekking off many light years in finding a pre-fab.
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Old 11-29-2004, 08:49 AM
Bryan Ekers Bryan Ekers is online now
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Originally Posted by tim314
And as far as galactic civilizations, is there really that much incentive to expand beyond the point where we can even communicate with each other? If we extend ourselves more than 100 lightyears out, it would take a lifetime just to call home.
My guess is that if you're 100 light-years out, Earth is only "home" in the theoretical sense. Heck, within two generations, tops, many children of immigrants may view "the old country" wistfully, but with not a huge amount of desire to visit or communicate with it.

Actually, picture a generational colony sent out at slower-than-light, with no expectation of ever returning to Earth or communicating regularly with it. Technological progress continues on Earth, faster-than-light travel is developed and new colony ships are built and sent forth. When the STL colonists arrive and emerge from their hibernation chambers, they find their utopia already overrun by McDonald's and Wal-Mart, built by people for whom Earth is just a few hours away and thus with no desire to make anything radically new or different. That'd suck.
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Old 11-29-2004, 09:41 AM
Aagramn Aagramn is offline
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Originally Posted by bup
Fermi's paradox says that if there were advanced life out there, they should have colonized the galaxy by now, including our very habitable planet.

It's based on the observation that civilization and technology advance so quickly, compared to the billions of years of evolution it took to get intelligent life capable of advanced technology, that the odds of us and someone else developing in parallel, before one of us could colonize the whole galaxy, is basically nil.
A couple points. Firstly, building interstellar craft may prove to be impossible in practise, even if you have the technology to do it. Not many aliens would want to board one if it only had a 0.001% chance of success. Secondly, once you get to another world, you might have to spend hundreds of millions of years terraforming it before you could live there. Even if you found a planet which had evolved complex life, you probably wouldn't be able to eat any of the food there. We evolved on this planet, and our body chemistry is very sensitive to the presence of a whole range of chemicals, such as arsenic or lead. Basically, we can tolerate them in the abundance that we find them naturally on earth. A very similar planet with a slightly different composition would probably be poisionous to us.

Fermi's paradox seems to assume that technology can overcome any of these barriers, and that an alien civilization would have access to effectively unlimited resources.
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Old 11-29-2004, 09:43 AM
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Going back to the OP, does anyone know how many stars are within 20 light years of Earth? From memory, I think it's only a handful. Does anyone know the average density of the milky way (stars per cubic light-year)?
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Old 11-29-2004, 10:03 AM
Shrinking Violet Shrinking Violet is offline
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Going back to the OP, does anyone know how many stars are within 20 light years of Earth?
106.
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Old 11-29-2004, 10:15 AM
Loopydude Loopydude is offline
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Fermi's paradox seems to assume that technology can overcome any of these barriers, and that an alien civilization would have access to effectively unlimited resources.
Well, if we perfect the generation of practical power from nuclear fusion, about the only potentially limiting resource is deuterium, of which there is a vast and easily extractable supply here on Earth. With all that essentially free energy, creation of large usable stores of antimatter is basically just an engineering problem, and so now the mass:energy part of the equation is small enough that interstellar travel is quite feasible on a colony vessel of some sort. Maybe some folks wouldn't like the idea of leaving Earth forever, but I'm sure there are plenty who would be clamoring for a place on board, probably some of the same sorts of people who might set off across the ocean, believing they might fall off the edge if the round-Earthers goofed.

There aren't any Earth-like planets that we know of nearby; but there are lots of gas giants, some of them far enough away from their stars that if they posessed moons (which seems altogether likely), some of those moons could meet all the habitation requirements of human colonists capable of making the journey in the first place; and such worlds could be reached in just a few generations at even fairly modest speeds (like maybe 20-30% the speed of light). Given our colonial history on Earth, I see no reason to assume any of the above is impossible or unlikely. Would other civilizations be so indifferent as to refuse the adventure of the great beyond? One can only speculate.
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Old 11-29-2004, 04:11 PM
Chronos Chronos is offline
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So, it is still possible they are out there in this galaxy. However, there are two definite facts:

* The technology required to emit a galaxy-wide audible signal is only as advanced as that required to make a nuclear weapon.
* We appear to be the only ones ever to have done so.
We have not done so. We once sent a single signal in a very specific direction which could be detected by our own technology at Galactic distances. I believe that the resolution of the Araceibo telescope is approximately one degree; if this is accurate, then we've only transmitted to one part in 40,000 of the sky. If this is the same sort of effort that ET is devoting to the task, then it's no wonder at all that we haven't heard him call.
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Old 11-29-2004, 05:58 PM
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Well I will throw out my ignorance for all the World to gawp at, not to revel in it but to be disabused. I am not tracking.

If there are 700 billion solar masses in the Milky Way
http://www.astronomycafe.net/qadir/q76.html

How on earth (so to speak) can they all be visited in 1 million years at sublight speeds? Isn't that a rate of visiting 700,000 unique Stars a year?

Isn't a more logical number that they would visit, say 350 new Stars a year, and to do this steadily this presupposes many, many thousands of ships making journeys at once. At 350 new Star falls a year, with no repeats, wouldn't that take 2 Billion years? At 700 new stars a year a Billion years ....

I am now mathematician or cosmic theoretician, and am certainly not being chesty with anyone -- show the dumb guy what he isn't tracking
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Old 11-29-2004, 06:14 PM
Loopydude Loopydude is offline
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The idea is that a single colony seeds multiple colonies, which in turn seed their own colonies, etc. It's not a purely linear process, but rather the number of colonies increases, at least for a while, geometrically, and so the species (or more accurately, its sundry descendants) spreads out in all directions where worlds lie until virtually all habitable worlds are occupied.
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Old 11-29-2004, 06:37 PM
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I can't remember the name of the book, but some British theoretical physicist wrote a sequel to H. G. Wells's The Time Machine, the book basically serves, really, as a way of him explaining cosmological theory, and I only mention it so that if someone out there knows who it is, they can supply the name and a few more details.

Anyway, in one of his non=fiction writings, he states that if it's impossible to develop some form of FTL travel, then a spacefaring species will essentially strip themselves out of resources and collapse. This, of course, will happen to non-spacefaring species that much faster. I've not read the original piece by him, so I've no idea as to how plausible his statement is. Certainly sounds reasonable to me (but then again, I'm a space geek), and if we're unable to find a loophole in Einstein's theories, then it's pretty obvious why no one's shown up: They've collapsed before they could get here.
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Old 11-29-2004, 06:44 PM
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There's also the paranoid explanation for this deafining silence : others civilizations exist but they know it's very unwise to be noticed. So, they stay silent and if they explore anything, it's in a very discreet way.

IOW : there's *something* out there that all other civilizations are afraid of.

(or at least exploring the galaxy systematically ends up very badly for some reason, so the only existing civilizations are the silent and/or cautious and/or unadventurous ones)


I heard this explanation being advanced seriously, but I can't remember at all by whom.
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Old 11-29-2004, 07:16 PM
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Originally Posted by Loopydude
They could even be here right now, living among us, in disguise!
Presumably as Hungarians.
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Old 11-29-2004, 07:20 PM
Loopydude Loopydude is offline
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One solution that might be plausible is simply disease. As it is, medical technology is giving us severely decreasing marginal returns. Over the last couple centuries, average lifespans could increase by a dozen or more years through the simple use of soap and other means of sanitation we now take completely for granted. Most of the remaining diseases humans normally succumbed to were then virtually or completely eradicated by antibiotics and vaccines. When did we last see such a leap?

The really nasty pathogens we know of out there, things like Ebola and other hemorrhagic fever viruses, have the nice built-in safety of killing their hosts too quickly for them to spread it around widely. It's relatively easy to quarantine the remaining infected so that the virus never gets too far from its source.

But say you get something like an AIDS virus that can survive in aerosols and enter the body more easily. It's not impossible. All you need is one deadly, incurable, easily communicable virus that waits a few years before it finally kills its hosts, and is contagious while subclinical, just as HIV is. Millions could be infected before we were even aware, and billions could die before we found a way to manage it.

The more dense, widespread, and mobile the human species is on Earth, the more vulnerable we are to the uncontrolled spread of deadly pathogens, if they cannot be detected quickly enough to avoid a pandemic, and/or we cannot rapidly find a cure. We have thus-far avoided such a disaster with AIDS because it's so difficult to transmit. If we do encounter another "superbug", we may not be so fortunate next time. I sometimes wonder if the "better mousetrap" rule holds inexorably for microbes and viruses, such that as soon as new hosts present themselves in large numbers, the rapidity with which microorganisms/viruses can reproduce virtually guarantees the evolution of new pathogens that can take advantage of the available habitat. Given this continual problem, it's basically a numbers game until we either lick all disease for good, or we finally come into contact with something that licks us. The human species may be periodically knocked down such that it makes it very hard for us to devote our resources to major endeavors like interstellar travel; and what holds true for life here would likely hold true for life elsewhere, if it fits similar paradigms.
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Old 12-17-2016, 01:10 PM
Leo Bloom Leo Bloom is offline
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Would Contact with Extraterrestrials Benefit or Harm Humanity? A Scenario Analysis
Seth D. Baum,1 Jacob D. Haqq-Misra,2 & Shawn D. Domagal-Goldman3
1. Department of Geography, Pennsylvania State University. http://sethbaum.com 2. Department of Meteorology, Pennsylvania State University 3. NASA Planetary Science Division
Acta Astronautica, 2011, 68(11-12): 2114-2129


This superbly entertaining article is about how to even formulate questions such as "do they eat us or milk us" or "can we do it to them" [my quote marks, my examples, i.e. not in paper].

The introductory material has rich references to scientific and fictional approaches to the Fermi Paradox, and that section I excerpt and condense here. ["ETI" is "extraterrestrial intelligence" and "METI" "messages sent [by us] to extraterrestrial intelligence.]
The Fermi paradox

So far, no extraterrestrial civilization has been unequivocally observed by humans. ...Enrico Fermi suggests that ETI should be widespread throughout the galaxy [8]. This conspicuous absence of extraterrestrials is often referred to as the Fermi paradox...three paradox resolutions are worthy of consideration in our discussion.

One: [...] life, or at least intelligence, is rare [...] If intelligence is rare, then it is quite unlikely that humanity would have detected ETI. In the extreme case, humanity is the only intelligent civilization in the galaxy or even in the universe. Along the same lines, other intelligent civilizations may be beyond the physical limits of contact even if they do exist [15-17]. These scenarios are of limited value to this paper because they imply that contact with ETI is impossible.

[Two:] A second possible resolution [...] derives from the challenges of expanding rapidly throughout the galaxy. Perhaps rapid expansion is unsustainable at the galactic scale, just as rapid expansion is often unsustainable here on Earth. This suggests that the absence of extraterrestrials might be explained by the fact that exponential growth is an unsustainable development pattern for intelligent civilizations [18], a response to the Fermi paradox known as the Sustainability Solution [19]. [which states] rapidly expanding civilizations may face ecological collapse after colonizing the galaxy, analogous to the fate of Easter Island [20].

On the other hand, the galaxy could be teeming with ETI that expand too slowly to have reached Earth yet [21]. These slowly expanding ETI civilizations could still be detected by us or send us messages, and their nature as slow expanders has some implications for contact scenarios.

[Three:] ETI are actually already widespread throughout the galaxy but are somehow invisible to us. The ETI could be unintentionally [or intentional]. The intentional form of this solution is sometimes known as the Zoo Hypothesis [22] because it implies that ETI are treating Earth like a wildlife preserve to be observed but not fully incorporated into the Galactic Club. This idea has been popularized through the Star Trek series as the “prime directive” for non- interference with a primitive culture. [...] They may be waiting until we have reached a sufficient level of sophistication as a society such as the start of a METI program or the discovery of light speed travel [22-23], or they could be applying a societal benchmark such as sustainable development or international unity. The possibility that the Zoo Hypothesis explains the Fermi paradox has several important implications for contact scenarios.

"ETA" ["extraterrestrial assumption"]: It too 12 years of an expanding Universe for Leo to contact the dead.

Last edited by Leo Bloom; 12-17-2016 at 01:14 PM.
  #32  
Old 12-17-2016, 01:25 PM
Leo Bloom Leo Bloom is offline
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[BTW, how much has the Universe expanded in the last 12 years?]
  #33  
Old 12-17-2016, 02:36 PM
Hari Seldon Hari Seldon is offline
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Originally Posted by bonzer View Post
Presumably as Hungarians.
Ninjaed.

For those who don't get this, let me explain. When Leo Szilard heard Fermi's paradox, his response was that they are already here. We call them Hungarians. (For the record, Szilard was Hungarian.)
  #34  
Old 12-17-2016, 02:47 PM
Okrahoma Okrahoma is offline
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Originally Posted by Bryan Ekers View Post
Actually, picture a generational colony sent out at slower-than-light, with no expectation of ever returning to Earth or communicating regularly with it. Technological progress continues on Earth, faster-than-light travel is developed and new colony ships are built and sent forth. When the STL colonists arrive and emerge from their hibernation chambers, they find their utopia already overrun by McDonald's and Wal-Mart, built by people for whom Earth is just a few hours away and thus with no desire to make anything radically new or different. That'd suck.
Smaller scale, (first manned landing on Mars, disrupted by someone getting there from Earth through a wormhole): the beginning of Pandora's Star, by Peter F Hamilton.
  #35  
Old 12-17-2016, 02:48 PM
doubleminus doubleminus is offline
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There is also the simplest of assumptions: There is no one else around, and we are alone. Until someone comes up with a convincing theory of how the first DNA was created and that it was not a freakish low-probability event, this is my zero hypothesis.
  #36  
Old 12-17-2016, 02:49 PM
Darren Garrison Darren Garrison is offline
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Originally Posted by Leo Bloom View Post
[BTW, how much has the Universe expanded in the last 12 years?]
Nobody knows how big the universe is. It could be a little bigger than the edge of the visible universe, it cold be trillions of times bigger. So that isn't an answerable question.
  #37  
Old 12-17-2016, 03:39 PM
LSLGuy LSLGuy is offline
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Originally Posted by Leo Bloom View Post
...
This superbly entertaining article is about how to even formulate questions such as "do they eat us or milk us" or "can we do it to them" [my quote marks, my examples, i.e. not in paper].
...
"ETA" ["extraterrestrial assumption"]: It too 12 years of an expanding Universe for Leo to contact the dead.
Leo, I gotta say you find the most amazing stuff. And on quite a wide variety of topics.

Part of me really wants to ask how you do it and part of me is afraid to find out.
  #38  
Old 12-17-2016, 06:01 PM
Leo Bloom Leo Bloom is offline
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Originally Posted by Hari Seldon View Post
Ninjaed...
I'm confused about time dilation here. Or else Hari Seldon is saying, like Maxwell Smart, he missed posting by that much...
  #39  
Old 12-17-2016, 07:02 PM
LSLGuy LSLGuy is offline
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I think Hari is saying that as you get older your lightning ninja reactions lose a step or two. He's slowed down to swinging his rhetorical katana a mere 12 years too late to slay the enemy. He just needs to aim a little farther ahead of where the bad guys are.

Kinda the opposite of that old Viet Nam era chestnut:
Quote:
Outraged news reporter: Captain, how can you strafe women and children??!?
Grizzled F-100 pilot: Easy; you just don't lead 'em as much.

Last edited by LSLGuy; 12-17-2016 at 07:03 PM.
  #40  
Old 12-17-2016, 07:17 PM
panache45 panache45 is offline
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Originally Posted by LSLGuy View Post
Leo, I gotta say you find the most amazing stuff. And on quite a wide variety of topics.

Part of me really wants to ask how you do it and part of me is afraid to find out.
Perhaps Leo is the ETI who has already arrived.

Last edited by panache45; 12-17-2016 at 07:19 PM.
  #41  
Old 12-17-2016, 07:26 PM
LSLGuy LSLGuy is offline
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I read Leo's referenced paper. All 33 pages. Most of their scenarios end badly for humanity. Very badly.

If he is the ETI, we're screwed. Maybe we can make nice.

Umm, err, LISTEN UP FOLKS! ... I for one welcome our new Leo Overlords. I hope he believes me.
  #42  
Old 12-18-2016, 09:45 AM
Leo Bloom Leo Bloom is offline
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Greeting.
  #43  
Old 12-18-2016, 11:01 AM
Andy L Andy L is offline
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I can't remember the name of the book, but some British theoretical physicist wrote a sequel to H. G. Wells's The Time Machine, the book basically serves, really, as a way of him explaining cosmological theory, and I only mention it so that if someone out there knows who it is, they can supply the name and a few more details.
That sounds like Stephen Baxter's "The Time Ships."
  #44  
Old 12-18-2016, 05:18 PM
bonzer bonzer is offline
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Quote:
Originally Posted by Hari Seldon View Post
Ninjaed.
And, as others have noticed, only a dozen years too late at that.

Quote:
For those who don't get this, let me explain. When Leo Szilard heard Fermi's paradox, his response was that they are already here. We call them Hungarians. (For the record, Szilard was Hungarian.)
Did Szilard ever make the joke in the context of the Fermi Paradox? I'm not sure he did. Though I'm willing to be corrected.
Because, at this remove, I don't think that's the specific joke I was making. No, the point is that there was the spectacular early-20th century generation of Hungarian mathematicians and physicists: Szilard, Tellar, Von Neumann and Wigner. Together with the fact that Hungarian doesn't fit within the Indo-European languages, the traditional joke - and, without checking, I can well believe that Szilard furthered it - was that the Hungarians were "Martians". As in The Martians of Science - which I haven't read.

Evidence to the contrary, I'd be fairly sure that the joke that Hungarians are extraterrestrials is otherwise traditionally independent of the Fermi Paradox.

But still. Just saying ... Twelve years on.
  #45  
Old 12-18-2016, 06:50 PM
Leo Bloom Leo Bloom is offline
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Teller you used to say he spoke 12 languages, all in Hungarian.
  #46  
Old 12-18-2016, 07:46 PM
LSLGuy LSLGuy is offline
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In the late 1970s I heard him (Teller) in person giving an emeritus lecture at my university. He would have been 70 +/- 1 years old.

He totally was speaking English. But definitely doing it in Hungarian.

Last edited by LSLGuy; 12-18-2016 at 07:46 PM.
  #47  
Old 12-18-2016, 08:54 PM
Chronos Chronos is offline
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Interesting. I've long known that C programmers can write C code in any language, and Fortran programmers can write Fortran code in any language. But this is the first I've heard that Hungarian speakers can give a Hungarian talk in other languages.
  #48  
Old 12-18-2016, 11:21 PM
Leo Bloom Leo Bloom is offline
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Originally Posted by Leo Bloom View Post
Teller you used to say he spoke 12 languages, all in Hungarian.
My only cite for this is my father, who met him somewhere at some Hungarian award ceremony.


ETA: FTR, A légpárnás hajóm tele van angolnákkal is the correct response when asking for directions at a street corner.

Last edited by Leo Bloom; 12-18-2016 at 11:25 PM.
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