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  1. 16 Aug '12 11:53 / 3 edits
    I am making the argument here that we can deduce that it is improbable of us finding intelligent alien life ( but cannot deduce the probability of unintelligent alien life being found ) within the next, say, one billion years.

    This is how:

    The universe is almost 14 billion years old.
    The very first planets formed in a little less than a billion years after the big bang but the first ones would have been too gaseous for it to be likely for life to formed on them. Lets make a guess here that the first planets to form in significant numbers and with conditions suitable for life formation and subsequent evolution did no occur until about ~10 billion years ago; a reasonable guess I think.
    Now; life on earth started about ~3.7 billion years ago and, since earth life is the only example of life we know of that started and then evolved into intelligent life, we should make the educated guess that typically it takes very roughly about ~4 billion years to go from abiogenesis to intelligent life.
    OK, so there is nothing obvious that could have stopped alien life forming ~10 billion years ago and then evolving into intelligent life ~4 billion years after that.
    Therefore, there is no obvious reason to think that it would be unlikely that, if there IS intelligent alien life in our universe, at least some intelligent alien life existed about
    10 – 4 = 6 billion years ago.
    In fact, I would say we could deduce that IF there is intelligent alien life in our universe ( a big IF ) then there was probably also intelligent alien life in our universe 6 billion years ago.

    But if there was alien life 6 billion years ago, then at least some of those species would have had the culture of keep exploring and spreading and multiplying and space-travel and colonising new planets. If, say, such an alien species found our planet, say, a billion years ago, they would have completely colonised our planet and we would not be here because they would still dominate this planet and also we would probably not had a chance to evolve into existence!

    We can now deduce certain probabilities from this. For example, if such an intelligent space travelling alien species existed within our galaxy, these intelligent space travelling aliens would have almost inevitably found earth and colonised and dominated it millions if not billions of years ago and thus we would not be here. So we can deduce from this that it is extremely unlikely that there is intelligent alien species within our galaxy.
    A similar argument can be used to deduce that it is unlikely that there are intelligent space travelling aliens less than ~10 million light years from our own and that would include the Andromeda galaxy.
    But to apply this line of reasoning for assessing the chances of intelligent life more than ~10 million light years from us, we must consider the effect of whether some kind of faster-than-light or 'warp drive' is possible:

    Firstly, IF faster-than-light travel IS possible AND if there exists intelligent space travelling aliens then surely at least one such species would have multiplied and spread throughout the universe by now because, after all, they would have existed for ~6 billion years which is more than enough time for them to work out how do do that. But, if that is the case, then they would have surely found and colonised and dominated our planet billions of years ago and we would then not be here.
    Therefore, we can deduce two things from this:

    1, IF faster-than-light travel IS possible then it is unlikely that there are any intelligent aliens in our universe and we are alone. So even if we achieve faster-than-light travel, we would almost certainly not ever find intelligent aliens.

    2, IF there are any intelligent aliens in our universe then it is very unlikely that faster-than-light travel is possible and it is very unlikely that there are any intelligent aliens within, say, a ~10 million light year radius from us. So even if we space travelled to the maximum extent and speed possible which would probably be only a small fraction of c, we would be unlikely to find any intelligent life within, say, the next billion years.

    -either way, we can deduce that it is improbable that we would or could find intelligent alien life within the next billion years.



    Of course, this tells us nothing about the probability of us finding unintelligent alien life within the next billion years such as alien microbes because, for all we know, all alien life is just microbial and us intelligent life is extremely atypical and freakish.
  2. 16 Aug '12 13:18
    Originally posted by humy
    Lets make a guess here that the first planets to form in significant numbers and with conditions suitable for life formation and subsequent evolution did no occur until about ~10 billion years ago; a reasonable guess I think.
    Based on what? Percentage of heavy elements in the universe?

    Now; life on earth started about ~3.7 billion years ago and, since earth life is the only example of life we know of that started and then evolved into intelligent life, we should make the educated guess that typically it takes very roughly about ~4 billion years to go from abiogenesis to intelligent life.
    Precisely because it is the only example we know of, make that guess rather uneducated.
    Life has undergone various mass extinctions of the higher life forms a number of times. This is, I would think, normal for any life bearing planet. Life changes the environment which in turn causes extinctions, as well as external factors such as asteroid impacts and orbit variations.

    Also our current society is a result of a technological feedback loop that started by chance. We don't really know what the probability of this happening really is, nor the probability of creatures capable of this is.
  3. 16 Aug '12 13:41 / 3 edits
    Originally posted by twhitehead
    Based on what? Percentage of heavy elements in the universe?

    [b]Now; life on earth started about ~3.7 billion years ago and, since earth life is the only example of life we know of that started and then evolved into intelligent life, we should make the educated guess that typically it takes very roughly about ~4 billion years to go from abiogenesis to ...[text shortened]... robability of this happening really is, nor the probability of creatures capable of this is.
    [/b]
    Based on what? Percentage of heavy elements in the universe?

    yes.

    I think we can rule out life been made out of just hydrogen and helium -right?
    Precisely because it is the only example we know of, make that guess rather uneducated.

    yes. Nevertheless, it is the best educated guess we can make Precisely because it is the only example we know of.
    We don't really know what the probability of this happening really is,

    right, so there is uncertainty in the uncertainty. We are just talking about purely subjective probabilities here and not statistical probabilities.
  4. Standard member sonhouse
    Fast and Curious
    16 Aug '12 16:14
    Originally posted by humy
    Based on what? Percentage of heavy elements in the universe?

    yes.

    I think we can rule out life been made out of just hydrogen and helium -right?
    Precisely because it is the only example we know of, make that guess rather uneducated.

    yes. Nevertheless, it is the best educated guess we can make Precisely because it ...[text shortened]... are just talking about purely subjective probabilities here and not statistical probabilities.
    Maybe there is an average of one intelligent species per galaxy.

    Given our own proven track record, none of our civilizations have even lasted 10,000 years much less the millions of years to go from one galaxy to another close one, so if our civilization is any indication of averages, a civilization won't last long enough for there to be significant contact.

    Same goes for trying to find SETI radio or laser signals or IR, whatever, if civilizations have problems lasting more than 10,000 years and there are say, 10 of them in our galaxy, a EM wavefront may only last 10,000 years and so the whole thing passes by our planet in 10,000 years. If we are not at the right stage, it doesn't matter how big our radio or other telescopes get, we miss that signal and it's gone, propagating out of the galaxy. We would probably have better luck scanning an entire galaxy, like the Magellanic clouds or Andromeda with VERY large telescopes. Even so, if the 10,000 year rule is true for most civilizations, if we read an intelligent signal, it has taken hundreds of thousands of years or in the case of Andromeda, couple of million years. So under the 10K year rule, the civilization making the transmission would be long gone anyway.

    In our own galaxy, there is room for dozens of such 10K civilizations where signals could cross the galaxy and new civilizations could spring up at any time but be totally unaware of each other in spite of the fact they could have receivers equally sensitive and dishes at least as big as we have now and never hear a thing.
  5. 16 Aug '12 17:32
    Originally posted by humy
    But if there was alien life 6 billion years ago, then at least some of those species would have had the culture of keep exploring and spreading and multiplying and space-travel and colonising new planets.
    I am somewhat sceptical about this. Interstellar travel is so difficult that I am not sure that humans well ever attempt it much less succeed. What would be the motivation?
    I know that in biology in general life tends to multiply and spread - those species that don't die out. But I am less convinced that this applies to a single species or that it applies to intelligent species. We may end up with negative population growth or near immortality, or living in virtual worlds, or .... we just don't know.
    Its even possible that supper human computers will take over. But again, will they attempt interstellar travel?
  6. 16 Aug '12 19:20 / 2 edits
    Originally posted by sonhouse
    Maybe there is an average of one intelligent species per galaxy.

    Given our own proven track record, none of our civilizations have even lasted 10,000 years much less the millions of years to go from one galaxy to another close one, so if our civilization is any indication of averages, a civilization won't last long enough for there to be significant con receivers equally sensitive and dishes at least as big as we have now and never hear a thing.
    Given our own proven track record, none of our civilizations have even lasted 10,000 years much less the millions of years to go from one galaxy to another close one, so if our civilization is any indication of averages, a civilization won't last long enough for there to be significant contact.

    but that is surely irrelevant here because it is how long a technological and intelligent species survives that counts here and not how long a particular civilisation of that species lasts that counts. If our current civilisation crumbles in ~10,000 years time, no doubt it would simply be replaced by another human civilisation and that civilisation can continue with space exploration. We ( or at least an intelligent species that evolved from us ) will almost certainly still be around in billions of years time because we are technological advanced species which will inevitably use technology and intelligence to always make at least some of us survive through any adversity that would make most other animal species extinct ( and not even a nuclear war will make our species extinct; just maybe knock it back for a few centuries ). Why couldn't that be the same with an alien species?

    Particular civilisation of an alien species may come and go often but a technological advanced species that was around 6 billion years ago would probably be still around now precisely because it is technological advanced ( thus, just like us, able to use technology and intelligence to survive through any adversity that would make most other animal species extinct ) and regardless of how many times it has a change of civilisation.
  7. 16 Aug '12 19:53 / 3 edits
    Originally posted by twhitehead
    I am somewhat sceptical about this. Interstellar travel is so difficult that I am not sure that humans well ever attempt it much less succeed. What would be the motivation?
    I know that in biology in general life tends to multiply and spread - those species that don't die out. But I am less convinced that this applies to a single species or that it applie that supper human computers will take over. But again, will they attempt interstellar travel?
    I am somewhat sceptical about this. Interstellar travel is so difficult that I am not sure that humans well ever attempt it much less succeed. What would be the motivation?

    I am not sure but I think you may be making the error here of assuming that there must be a rational motive for interstellar travel for us or aliens to do so.
    The problem is evolution would generally not evolve intelligent species to be perfectly rationally motivated because it is a blind sloppy process.

    The motivation to explore and colonise new land/territory is often very psychologically complex but anything but entirely rational and may come from, for example, a vague sense of adventure.
    Take us for example; what was the motivation of Columbus to attempt to sail around the world? I mean, was it purely rational with applied pure logic? Are the reasons for human explorers exploring and colonising new lands always rational? -I doubt it.
    Why do people climb tall mountains like mount Everest? -I actually don't know but, Whatever that reason, it must be seriously irrational.
    If we are anything to go by, the same would be true for intelligent aliens. Being intelligent doesn't equate with being purely rationally motivated.

    For the same reason, there would be a great many people that would be motivated to travel to and colonise new planets even where and when there is absolutely no rational reason to do so whatsoever! I bet if there was a hostile planet that was only just about inhabitable for intelligent life and Earth being paradise in comparison, there STILL be people that would want to go there and colonise if they could! I mean, just for starters, there are many people that want to colonise Mars which is insane if you think of it because Antarctica is more hospitable than the surface of Mars! Because at least Antarctica has a breathable atmosphere!
    It would be a fair bet that the same would be true for at least some alien species ( if they exist at all ) .

    will they attempt interstellar travel?

    I would say, if they can, yes!
  8. Standard member sonhouse
    Fast and Curious
    16 Aug '12 21:45
    Originally posted by humy
    Given our own proven track record, none of our civilizations have even lasted 10,000 years much less the millions of years to go from one galaxy to another close one, so if our civilization is any indication of averages, a civilization won't last long enough for there to be significant contact.

    but that is surely irrelevant here because it is ...[text shortened]... her animal species extinct ) and regardless of how many times it has a change of civilisation.
    Don't let the lure of technology go to your head. One thing we are running into right now is the pace of tech change is outpacing our ability to archive. I have a buddy who sells 78 RPM records, he has 25,000 of them, primo ones that he makes recordings of and puts them to a cd or cassette. So here is the problem. The original 78's will probably last a thousand years if taken care of. The same with 100% certainty cannot be said for CD's and cassettes. Now we have flash drives, hard drives and so forth but those will not last for centuries. Suppose for some reason our planetary civilization takes a major dump, say the world population crashes to less than 1% of the peak, so what used to be, say 10 billion, is now less than 100 million world wide. Now we lose technology. It is clear we have scientific knowledge that would help an up coming civilization and so say a thousand years goes by, population on the rise, crisis over and technology starts up again. Archaeologists dig into our times and finds a library of technology but they see a flash drive, and have no idea what to do with it, even assuming the bits are still there in the drive and ready to download given the proper equipment. Now these guys would see we had computers and such but wouldn't know the flash drive was the grandson of windows 8, and the only box they find is a future apple. So it can't be read. Now there are people working on that problem where some kind of solid metal gets engraved on a microscopic scale and can be read with just a microscope but will the future up coming dudes even have a microscope? We could put it all down on gold leaf or something with identical drawings in 30 languages in the hope that the future guys can decipher the thing.

    I remember one of the time machine movies, forget which one, but they thought about that and came up with a solution using these discs that you spin like we do with coins, except they were about a foot across and had information keyed in so that when it spins it projects an image and you see the data there.

    That would be assuming humanity went WAY back on the techno scale and were basically cave men looking for a hide out and one of them picks up the disc and drops it back on the surface of the reader machine when it spins and starts telling a story that is done in a non-language way.

    So if they go back far enough from a previous techno high culture, and they old one died because of running the planet down in resources, say no more easily mined metals or coal all gone, no oil, which takes 100 million years to replace.

    Then the up coming culture has nothing to bootstrap itself up like we have, going from wood fired furnaces/steam engines to gasoline and then the various green fuels, and probably in less than 100 years, fusion will be a done deal.

    That is all from us coming up from scratch and finding massive deposits of coal, oil, natural gas and so forth.

    If a greedy civilization such as ours uses it all up and we die off by the billions there will be nobody to run those future fusion plants and wind generators and tidal machines and so forth.

    So 100 years later, the fusion plants are piles of crumbling rust and radioactive to boot but there is now no gas, oil, fossil fuel at all and most of the copper is gone, no steel, etc.

    How will a new civilization overcome all that?

    I think our only hope for long term survival is to get the hell off Earth and get out into the galaxy, even if we have to do it at 0.5c. Get humanity spread out over say 1000 ly, then we won't die off just due to a random supernova being too close or the Earth undergoing a volcanic explosion like the major ones in Yellowstone so many thousands of years ago.

    If we get off Earth and establish ourselves on say 100 separate star systems, then we would be as a race, immune from all such local disasters. Lose a planet or two, 100% death in some natural disaster but the race goes on.

    There would have to be trade between such a civilization to maintain rough equality between star systems and so forth but losing that, say something happens that all 100 systems can't get to space anymore, one of them will probably fix the problem and get back on track.

    If that all happened here on Earth, goodbye humans.

    Earth is not a particularly benign place for humans in the long term, too many Krakatoa's and such, ice ages come and go and we could live out one of them but eventually if the Earth got blindsided by a flash asteroid, nothing would save us from that, and it happens regularly every 33 million years or so and we are due for one now!

    So we have to get the hell away from here and spread out.

    If other civilizations did that we would have a much longer time frame for their signals, assuming they don't advance beyond the need for EM signals, maybe modulated neutrino beams or some such, all the radio telescopes on the planet wouldn't pick that up.

    So there are a lot of variables about why we didn't immediately see a full dial of signals out there and maybe never will.

    Of course, it's like the lottery, if you get lucky and the aliens are within 40 ly or so and we pick that up, it's a new world. Assuming the aliens are not militant.....
  9. 17 Aug '12 08:04
    Originally posted by sonhouse
    So 100 years later, the fusion plants are piles of crumbling rust and radioactive to boot but there is now no gas, oil, fossil fuel at all and most of the copper is gone, no steel, etc.
    And where did the copper and iron all go? In reality, it should be all still available and largely already refined and ready for use. Recycling is often easier and cheaper than mining.
    Also, although fossil fuels are cheap, they are not the only sources of power. Water power for example pre-dated fossil fuels. In fact, not having cheap fossil fuels might actually spur the development of greener technologies. The biggest hindrance to green technology today is the fact that we subsidise fossil fuels for political reasons.

    I think our only hope for long term survival ....
    And I often wonder how strong a motivation we have for long term survival. We cant even be bothered to do anything about global warming, and you think we would build interstellar space ships?
  10. 17 Aug '12 08:48 / 5 edits
    Originally posted by twhitehead
    And where did the copper and iron all go? In reality, it should be all still available and largely already refined and ready for use. Recycling is often easier and cheaper than mining.
    Also, although fossil fuels are cheap, they are not the only sources of power. Water power for example pre-dated fossil fuels. In fact, not having cheap fossil fuels might ...[text shortened]... ered to do anything about global warming, and you think we would build interstellar space ships?
    And I often wonder how strong a motivation we have for long term survival.

    actually, I don't think we need to think about long term survival to survive long term ( although it really would help a lot ) .
    Even if we NEVER think about long term survival and think about a million years time, despite world famines, warfare, and depletion of fossil fuels, we are virtually guaranteed to be around ( either as our current species or as a descendent species ) in a billion years time. That is because, despite the stupidity of man, some of us will always be willing to use our intelligence and technology to survive through any given disaster.

    Take for example the depletion of fossil fuels; lets say, through stupidity and short-termism, we WILL let them run out before fully developing sustainable alternatives. I have no doubt this would cause a global economic collapse and a world famine. But we are not so dependent on fossil fuels that NONE of us cannot adapt and survive without them! And it is inevitable that some of us would survive through such a man-made disaster to then rebuild civilisation and multiply so that, in perhaps ~300 years later, not only would our species would be very much alive but it would be thriving ( and using solar/wind power etc for generating ALL its energy ) .

    So there is good reason to suppose we ( or a descendent species evolved from ours ) will probably be around in a billion years time although beyond that we would need to space travel to survive because our expanding sun will make our Earth too hot but SURELY by then our technology will be sufficiently advanced to space travel to other solar systems! I mean, just look at the astonishing rate of technological progress we made in just the last 100 years and then consider that a billion years is 10 million times that. No doubt that progress will greatly slow as we bumper-up against various fundamental limits of what can physically be achieved ( mainly imposed by the laws of physics but there are also other constraints ) but those limits are not be sufficient to stop us space travelling to other solar systems so I have no doubt that we will.
  11. Standard member sonhouse
    Fast and Curious
    17 Aug '12 16:12
    Originally posted by humy
    And I often wonder how strong a motivation we have for long term survival.

    actually, I don't think we need to think about long term survival to survive long term ( although it really would help a lot ) .
    Even if we NEVER think about long term survival and think about a million years time, despite world famines, warfare, and depletion of foss ...[text shortened]... sufficient to stop us space travelling to other solar systems so I have no doubt that we will.
    I hope your optimism works out. One asteroid hit and all that is gone, we could be literally wiped out to the last person by one of those things. That said, I think we would have a better chance of SOME people surviving that catastrophe (people in caves already because of war, underground railways and such. The big problem would be feeding the survivors. The one that hit in the Yucatan caused a firestorm with about a 3000 mile radius. To say nothing of 700 foot high drifts as far away as Burmuda.

    All that could certainly ruin your day.

    We do have the beginnings of an asteroid watch scope systems but one asteroid can sneak in unannounced and hit in spite of the watch system. The slow ones we can get decades of advance warning. The fast ones are the ones that can get you despite diligence.

    Long term, Earth has another problem, you talk about 1 billion years.

    We may not have that much time. When the sun runs out of fuel, it will inexorably expand and perhaps become as large as the entire orbit of Earth, 1 AU in radius.

    That can also ruin your day

    But long before that happens the sun will get hotter so we probably don't have your billion year head start.

    Besides, the time from the Cambrian explosion is only about 500 million years and Earth has gone through a LOT of biological changes in that time.

    I would be surprised if intelligence is around on Earth even in 10 million years much less than 1 billion.

    I think we have our chance right now to build some kind of interstellar ship, if we don't, the world can catch us unawares and kick our butt.
  12. 17 Aug '12 17:21 / 4 edits
    Originally posted by sonhouse
    I hope your optimism works out. One asteroid hit and all that is gone, we could be literally wiped out to the last person by one of those things. That said, I think we would have a better chance of SOME people surviving that catastrophe (people in caves already because of war, underground railways and such. The big problem would be feeding the survivors. Th ome kind of interstellar ship, if we don't, the world can catch us unawares and kick our butt.
    It would be extremely unlikely that we would be made extinct by an asteroid because we would at least get a few weeks warning because, at any one time, there are many astronomers looking at the sky and one will be bound to spot it heading our way well before it hits. That would give us more than the required time for a great many people to make preparations ( at least those that can ) and stock up for a long global winter and guarantee at least SOME of us will survive through it and then slowly remultiply and rebuild civilisation. I would say, short of an unlikely extreme disaster such as a black hole entering our solar system or a planet colliding into the Earth etc, we ( or a descendent species ) would almost certainly be around in a billion years time and even almost certainly be around in ten billion years time thanks to space travel!
    And once we do colonise other planets ( esp in other solar systems other than our own ) which I am sure will easily happen well within the next million years (and this is assuming there cannot be such thing as warp drive! ), then even if a disaster destroys all life on Earth including human life, we would be guaranteed to be still around in a billion years because there would always be some of us still around alive somewhere in the universe! ( well, at least until entropy makes it uninhabitable )
  13. Subscriber AThousandYoung
    Do ya think?
    17 Aug '12 19:45
    Originally posted by humy
    I am somewhat sceptical about this. Interstellar travel is so difficult that I am not sure that humans well ever attempt it much less succeed. What would be the motivation?

    I am not sure but I think you may be making the error here of assuming that there must be a rational motive for interstellar travel for us or aliens to do so.
    The ...[text shortened]... .

    will they attempt interstellar travel?

    I would say, if they can, yes!
    I don't disagree with your overall point, but Columbus' journey was highly rational. Educated people have known since ancient Greece that the world is a sphere. It's the stupid masses and religious zealots that did not know this. Columbus was trying to take advantage of this fact to establish a trade route to India because the spice trade was IMMENSELY profitable and the Portuguese controlled the around-Africa route, while any number of civilizations controlled the overland route. So Columbus, Ferdinand and Isabella made a very rational choice to send him west.
  14. 17 Aug '12 19:55 / 1 edit
    Originally posted by AThousandYoung
    I don't disagree with your overall point, but Columbus' journey was highly rational. Educated people have known since ancient Greece that the world is a sphere. It's the stupid masses and religious zealots that did not know this. Columbus was trying to take advantage of this fact to establish a trade route to India because the spice trade was IMMEN ...[text shortened]... and route. So Columbus, Ferdinand and Isabella made a very rational choice to send him west.
    I certainly would not imply that Columbus was not more rational than “the stupid masses and religious zealots” nor that he was 'irrational' ( in character ) particularly. That certainly was not the point I was making at all.
  15. Standard member sonhouse
    Fast and Curious
    17 Aug '12 20:36
    Originally posted by humy
    It would be extremely unlikely that we would be made extinct by an asteroid because we would at least get a few weeks warning because, at any one time, there are many astronomers looking at the sky and one will be bound to spot it heading our way well before it hits. That would give us more than the required time for a great many people to make preparations ( a ...[text shortened]... around alive somewhere in the universe! ( well, at least until entropy makes it uninhabitable )
    It will be a while before we can say we get minimum a few weeks heads up. The system as it is has already failed twice. Asteroids have popped up going like a bat out of hell between the Earth and the moon, total surprise time. They were not too big, like a small mountain but still a piece that size could wreck a few states, it would be more than a city buster for sure, probably more like a thousand megaton H bomb.