[HN Gopher] Alone in a Crowded Milky Way
___________________________________________________________________
Alone in a Crowded Milky Way
Author : BerislavLopac
Score : 161 points
Date : 2020-01-01 13:57 UTC (9 hours ago)
(HTM) web link (www.scientificamerican.com)
(TXT) w3m dump (www.scientificamerican.com)
| mnemonicsloth wrote:
| It bothers me that the authors' assumptions are so controversial
| and that they hide them in the middle of the article.
|
| In the simulations the authors are using, civilizations have
| lifetimes, meaning that all of them end after a while. And that
| simply isn't supported by events. Technological civilization has
| never vanished even from our little one-planet civilization.
| Polities do decline, but there is usually someone there to pick
| up the pieces. In an interstellar civilization there would be
| more recovery opportunities: interstellar visitors who arrive to
| see why a collapsed planet went offline.
|
| The authors of this piece are asking us not just to assume that
| simultaneous disaster is possible on ten, a hundred, or a
| thousand planets. They are asking us to assume that it happens to
| every single time a civilization has achieved interstellar
| travel, and that it has been happening for the last ten billion
| years.
|
| Simultaneous catastrophes on thousands of worlds affecting
| millions of species for billions of years? Life arising only once
| could very well be the more plausible option.
| stevev wrote:
| I am intrigued by the simulation theory. That we as a species has
| reached a certain level of advancement to simulate a reality and
| experience it; or we may just be npcs or temporary programs for
| another intelligent race in this simulation.
|
| We could also be a zoo/prison planet far into enemy territory.
| Currently being experimented and observed. Hybridization in order
| to infiltrate our actual civilization that's located elsewhere.
| carapace wrote:
| Fascinating theory, but we aren't Pitcairn Island.
|
| > Why, then, have we found no irrefutable evidence of aliens
| visiting Earth?
|
| We have evidence, it just gets "refuted" for psychological
| reasons. The Fermi Paradox is a Rorschach test, and has nothing
| to do with reality.
|
| In reality, humans in every culture have recorded incidents of
| communications with non-human intelligences.[0]
|
| In reality, the Brazilian Military has gotten much less coy about
| UFO phenomenon in recent years and has started declassifying
| documents. Their overall conclusion is that, whatever they are,
| UFOs are real, pose no national security threat, and should be
| researched and discussed by society at large, with some urgency.
|
| Here's a fascinating lecture by a Brazilian UFO researcher about
| the overall situation in Brazil and he describes three encounters
| that are known to have government involvement (so the researchers
| know what to ask about, in these cases.)
|
| "Operation Saucer - UFO military encounters in the Brazilian
| jungle" https://www.youtube.com/watch?v=ThkmRsEBOY0
|
| > In 1977, numerous UFOs were seen in the Brazilian city of
| Colares, Para. The UFOs fired light beams at people, causing
| injuries and sucking blood from 400 witnesses. After a rise in
| local concern, the mayor of the city requested help from the Air
| Force. Operation Saucer started, during which numerous photos
| were taken and testimonies collected. Operation Saucer is just
| one of the compelling cases which A. J. Gevaerd, editor of
| Brazilian UFO magazine, talked about in his latest lecture in
| Copenhagen, paving the way for complete Disclosure in his
| country. Kudos to Exopolitics Denmark for setting up their
| excellent annual conference at the Danish National Museum on
| September 26 in Copenhagen!
|
| The first case involves thousands of people, living on an island
| in the Amazon, who were attacked by UFOs over a period of several
| years (1975-1977 IIRC). Flying cans with visible pilots were
| shooting people with bending "light" beams and sucking up their
| blood. It got so bad that thousands of people evacuated and the
| Brazilian Army sent in a unit to find out what was going on and
| try to make contact. I won't spoil the rest of the story here.
|
| To me, the strangest thing I can see is the question: Why would
| people (aliens or humans) who have evidently advanced technology
| go around attacking poor villagers to _suck their blood_!? WTF?
|
| [0] (I myself once attended a event at an airport hotel at which
| some purple telepathic space dolphins were guest lecturers. FWIW,
| their basic TL;DR: was "Be nice to each other." Aliens were
| attending underground raves in Seattle in the 90's.)
| [deleted]
| CuriousReader13 wrote:
| What's the point of settling on planets if you can sustainably
| develop anywhere in space, which I think is within the reach of
| any typical space-faring civilization?
| m4rtink wrote:
| I guess, you can do both. Well unless you want to use the mass
| of the planet for a more efficint purpose, eq. habitat swarm.
| [deleted]
| [deleted]
| rainworld wrote:
| More likely we really are alone:
| http://aleph.se/andart2/space/seti/dissolving-the-fermi-para...
| bagacrap wrote:
| That paper only claims that it is _plausible_ we 're alone,
| meaning the Fermi paradox is only a question, not a conundrum.
| jnurmine wrote:
| On Earth, there have been previous life-forms which have died
| out, there have been more or less intelligent life-forms which
| have died out (various dinosaurs and exhausted branches of
| hominids etc.), there have been previous civilizations with
| varying scientifical/technological achievements; but there has
| never been a species on Earth which has created a civilization as
| advanced as humans have.
|
| So, we are the first ones to reach this point on the Earth. Not
| the first ones ever, but first ones to get this far.
|
| If we assume the patterns of evolution observed on the Earth are
| nothing specific to Earth and they repeat throughout the
| Universe, there are/have most likely been life-forms (simple and
| complex) of varying degrees of intelligence, as well as
| civilizations of varying degrees of technological advancement.
|
| However, since we apparently see absolutely no trace of anyone
| else, either they failed to successfully bootstrap their colonies
| outside of their home planet/moon, or we got here first. It's
| unlikely, and absence of evidence is not evidence of absence, but
| someone has to be the first. Maybe it's us, from our little blue
| planet.
| roca wrote:
| I find most Fermi-paradox arguments drift towards being too
| biology-centric even if they acknowledge the possibility or
| probability of a transition to machine-based life.
|
| For example this paper assumes that you need classic "habitable
| worlds" to colonize a solar system, but it's unclear why machines
| would need more than relatively small rocks or comets.
|
| The paper also assumes that each colony needs to operate as a
| continuous entity and can therefore collapse or experience
| massive cultural shift. But if it's all machines, then you can
| put some powered-off seed ships in long orbits for cheap self-
| recolonization (seems strictly easier than crossing interstellar
| space in the first place).
|
| I'd like to see more studies on the feasibility of those ultra-
| long-lifetime interstellar ships (assuming plausible tech like
| general AI). Maybe there are thermodynamic or other reasons why
| that can't be done.
|
| (Personally I'm in the camp of "abiogenesis is actually really
| hard so we're the first civilization in our light-cone; the
| doomsday argument holds, and will be a theistic eschaton".)
| ajnin wrote:
| Machines need to be maintained. Machines of useful complexity
| include such parts as microprocessors. To create new or
| replacement parts, nothing less than the full Earth industrial
| complex is required. It's not clear how to package all that in
| a ship, including enough reserves to bootstrap an industry up
| to the point it is possible to build microprocessors. I doubt
| that "machine life" could subsist on a small barren rock with
| more success than biological life.
| [deleted]
| Aperocky wrote:
| Exactly, any such ship would be packaged around a processing
| unit factory
| roca wrote:
| It's very interesting to consider what would be required for
| a minimal industrial complex that supports microprocessors.
| My intuition is that it would be much smaller than "the full
| Earth industrial complex". Seems like a question that is
| actually answerable with research, and potentially important
| too as a hedge against our current industrial complex
| collapsing.
| robbiep wrote:
| Here's an article on that:
| http://caseyexaustralia.blogspot.com/2018/09/how-to-
| industri...
| roca wrote:
| Excellent link, thanks! That's exactly the sort of
| analysis required, though a lot more is needed.
|
| I didn't follow why mining has to be (or should be) so
| human-labor-intensive.
| isoprophlex wrote:
| Some fun ideas, because there's absolutely no reason why life
| should be so biological, as you say:
|
| - Some ancient civ managed to run computing hardware on the
| surface of cooler stars (there are stars that allow non trivial
| surface chemistry)
|
| - the same but with gas giant planets near their metallic or
| rocky cores
|
| - Gamma ray bursts are galactic compute nodes syncing data
| mouzogu wrote:
| My theory is that any advanced civilisation reaches a point at
| which a vast amount of destructive power becomes accessible to
| individuals. At this point it becomes only matter of time until
| that civilisation is destroyed.
|
| The analogy I use is to imagine that every adult human on Earth
| woke up tomorrow morning with a button on their wrist that could
| destroy the Earth. How long do you think we would last?
|
| We haven't reached a stage where an individual can create a
| nuclear bomb, a new kind of super-virus or some other doomsday
| weapon but I imagine its not an implausible scenario in the
| future. I think this is kind of a wall that all advanced
| civilisation may hit at some point.
| merpnderp wrote:
| It's not hard to imagine in the near future that having a PhD
| in biology and access to a moderately equipped lab would grant
| a person the ability to create super plagues capable of killing
| most humans.
|
| Couple that with the wide spread nihilism that wants to destroy
| the world because they can't stand the injustice of life, and
| it's a pretty good bet our time as a species is limited here.
|
| If I were king for a day I'd do everything I could to get the
| message out that things are getting better, injustice is
| shrinking every year, and there is hope.
| Aperocky wrote:
| A way out would be to quickly move our brain to machines and
| build fully autonomous and self sustaining asteroid sized
| ships (could be built in situ). To function as backups and
| spreader for our civilization
| edjrage wrote:
| Nihilism has nothing to do with people who "can't stand the
| injustice of life", nor does it imply wanting to destroy the
| world. Please inform yourself.
|
| https://en.wikipedia.org/wiki/Nihilism
| alecco wrote:
| Probably an arms race would make defense technology good enough
| to limit the consequences of it.
| zzzeek wrote:
| this is a good theory but you don't even have to look at it as,
| "each being has the will to destroy everyone". way more likely
| that it's a natural byproduct of existence that can't be
| adequately anticipated such that the species can do something
| about it. We're already on the edge of waiting for the bacteria
| that can't be killed, the climate disaster that destroys our
| food supply, etc. (you might say climate disaster is adequately
| anticipated, but while science is anticipating it, the whole of
| the species is unfortunately not).
| qw wrote:
| If that happened you would probably see (wealthy) people
| migrating to underground bunkers to protect themselves and
| interact using VR. That could be one of the explanations why
| they don't go out to create colonies and make enough noise for
| us to detect them.
| tniemi wrote:
| Like "Mail order CRISPR kits for everyone"?
|
| The scary part is that there actually already is a web site
| that sells those...
| gfodor wrote:
| This is an interesting theory I have considered as well,
| however there is a reason to disbelieve it. It assumes at its
| core the diffusion of some form of highly destructive
| technology, and that the technology will be unleashed in an
| irreversible way before it can be recognized and "put back in
| the box", or it can't be "put back in the box".
|
| These assumptions individually seem strong but together they
| get quite weak. For example, diffusion of civilization over
| several planets before this technology is diffused provides a
| potential firewall. (For example, once the technology is
| recognized, an orderly exodus is made which forcibly leaves
| behind any trace of it.) Alternatively, the diffusion itself
| may not occur as well, similar to the current life-ending
| technologies we have now that can only be created by state
| actors.
|
| It is a legitimate prospect -- but hinges upon several aspects
| hung together to get to a point where it's an inductive
| invariant explaining fermi.
| NortySpock wrote:
| Maybe a biological weapon being unleashed from some genocidal
| nutcase's basement hobby laboratory?
| Paperweight wrote:
| This is why they're orbiting at a safe distance and waiting to
| see what we do when we discover antimatter bombs for ourselves.
| graycat wrote:
| (1) Biological life colonizing other planets? The individual
| beings would not live long enough to make the journey. So, would
| have to have reproduction of generations during the trip, and
| that means one heck of a big spaceship. Then for any of the
| motivations, I would be easier just to stay home.
|
| (2) Sending self-reproducing robots? Why? What's the motivation?
| E.g., why should I consent to spending big tax bucks to send
| robots out that would need millions of years to have any effect
| back on earth? I won't.
|
| Okay, there is the scenario that a planet is ready to die, and
| the beings want to move to a new land. Again, for anyone alive,
| what is their motivation? That is, either stay home and wait for,
| say, the star to nova or just die on a long space trip? Just stay
| home; as bad as a star nova would be, just stay home.
|
| One more scenario is that fast space travel is possible but uses
| physics we don't understand and, thus, can't detect.
| pjdorrell wrote:
| The boring answer is that the initial origin of life depends on a
| sequence of extremely improbable chemical reactions (even given
| the prior existence of the most favourable possible "organic
| soup"), and there is no other life of any kind in the observable
| universe.
| dade_ wrote:
| I find it strange that the author thinks that Dark Forest theory
| is implausible. It strikes me as the simplest of explanations.
|
| Granted Cixin Liu stretches physics into all sorts of implausible
| places, but it does make a strong argument for the theory.
|
| https://www.goodreads.com/book/show/48838110-three-body-prob...
| gilbetron wrote:
| I loved the series, but the physics was horrendous, and I don't
| agree it made a strong argument for the Dark Forest theory. It
| made an enjoyable, interesting read about the Dark Forest
| theory, but the schemes the author used didn't make sense and
| wouldn't result in the universe as described in the books.
| fsloth wrote:
| Yeah, the book was about allegories and situations. The plot
| devices were intended to drive certain plot elements, not to
| be in the Clarkean way the first principle driving rationale
| for the work.
|
| The trilogy is very enjoyable!
| fsloth wrote:
| The dark forest theory works wonderfully as a plot device in
| the book. That trilogy is the best sci-fi I've read after
| Banks, Clarke and Asimov, hands down.
|
| But, if you stop and think about it, in the real universe it
| has two gaping problems:
|
| First, The Dark Forest theory depends on the capability and
| willingness to develop world destroying devices.
|
| Second, it depends on the likelihood that the species you
| detect has not yet spread to other systems. If it has,
| congratulations, you have started a shooting war with an enemy
| whose threat level you have no gauge of. Some with an
| inclination of game theory might want to figure this out
| through better, though.
| creato wrote:
| > First, The Dark Forest theory depends on the capability and
| willingness to develop world destroying devices.
|
| Any civilization capable of traveling to another solar system
| has this capability: just take one of their ships designed to
| accelerate to significant fractions of the speed of light and
| decelerate at the other end of the journey, set a course, and
| simply don't decelerate.
|
| > Second, it depends on the likelihood that the species you
| detect has not yet spread to other systems. If it has,
| congratulations, you have started a shooting war with an
| enemy whose threat level you have no gauge of. Some with an
| inclination of game theory might want to figure this out
| through better, though.
|
| There's a good chance the above described weapon would be
| nearly undetectable and untraceable. For at least the latter
| half of its journey, it's just a chunk of mass traveling
| through space, emitting no signals. It would also be only a
| small factor difference in capability (0-1 more accelerations
| and decelerations than an actual interstellar transit) to
| send it from a different part of the galaxy.
| detritus wrote:
| Another book in this vein, although distinctly more
| uncompromising in its conclusion, is The Killing Star, by
| Charles R. Pellegrino and George Zebrowski.
| hindsightbias wrote:
| Available on Audible now. Hard to find it in print.
|
| Another series is Greg Bear's Forge of God
| jmull wrote:
| I loved those books, but the dark forest theory doesn't make
| sense. Given a dangerous universe it would make sense for a
| civilization to try to communicate with other civilizations to
| create alliances for mutual safety.
|
| The civilizations that are able to forge alliances will tend to
| out-compete lone wolves.
|
| Liu assumes that it is somehow a lot easier to wipe out a
| civilization than communicate with it, and that for some reason
| your civilization has to decide to wipe out another
| civilization without communicating with it.
| LoSboccacc wrote:
| alliances put some lower bound constraint on the logistic
| capabilities and density of the civilisations that form them.
|
| strategically speaking and stunning hostile unknowns a stable
| civilization controls a territory matching reasonable
| response time from the ready armies at their combat speed and
| necessarily a requirement for alliances to form is for these
| zones to overlap
|
| but if they are at such distance it negates one of the
| prerequisite for the dark forest theory, that civs are sparse
| enough for the chance of facing hostiles alone is on par with
| encountering non hostile civs
| krapp wrote:
| Interstellar space isn't an ocean, and star systems aren't
| countries. Analogies to Earth militaries and navies simply
| don't apply, the scale of space is too big.
|
| You're not going to form any sort of "alliance" over a
| distance of light-years, much less consider the fleets of
| hostile civilizations to be a threat by their proximity the
| way England once considered Spanish fleets a threat.
| There's no "reasonable response time" when allies will take
| years to hear your distress call, and more years to arrive.
| chmike wrote:
| I don't understand why ufological data is systematically ignored.
| This leads to biased reasoning.
| revscat wrote:
| I wouldn't say it is ignored, more that it isn't particularly
| useful. Shaky YouTube videos don't allow for much in the way of
| study. Even more convincing sources, such as that video
| released last year of the Tic Tac UFO, were interesting, but
| not all that useful.
| plutonorm wrote:
| I agree. To talk about the possibility is to commit scientific
| suicide. Even cautiously talking about the topic immediately
| outs you to others as a crackpot. I think it's undeserved.
| Especially when we are now seeing just how many habitable
| world's are out there. It seems plausible that we have been
| visited by curious extra terrestrial civilisations. The bizare
| patents coming out of the US navy suggest to me that no one
| knows where these things are coming from, if they are real.
| gfodor wrote:
| Indeed, if this theory is correct what we should expect to see
| are individual, small expedition-like visitations, which aligns
| roughly with the limited bits of credible ufo-related data.
| ryanSrich wrote:
| The article does a good job of explaining some of the numbers,
| but it's important to remember just how large they are.
|
| To a spacefaring civilization a million years might be the human
| equivalent of a decade.
|
| The sad truth is that intelligent humans (enough to think and act
| on thoughts of space travel) have barely existed on the cosmic
| timeline, and likely won't live long enough to know the answer to
| whether or not we're alone. Not because of some romanticized
| fermi gate paradoxical reasoning, but simply because we ran out
| of time.
| lonelappde wrote:
| What do you mean? How is running out of time different from a
| Fermi gate? Without a gate, why would time run out? The only
| natural limits are the time limit to colonize another planet,
| then another solar system, before our earth and sun lose their
| ability to sustain life.
| ws66 wrote:
| One thing I fail to see mentioned here and in such articles is
| the complexity of colonization. We are falling in the trap of
| "idea == profit". A lot needs to be done, and can go wrong,
| between both.
|
| Some examples I am thinking of, and I am certain people will have
| more... All are compounded by the LY distances between colonies
| and whatever home is:
|
| - Terraforming - It would be the exception that new planets are
| 100% hospitable to a specific species. How long to properly
| terraform, and then how long before the can get to a point where
| they can launch a new sub-colony? Need proper population,
| technology and resources.
|
| - Culture drift - how long can the colony and home share the same
| culture, with same values and objectives?
|
| - Political drift - Imagine you are part of a colony, with "home"
| some 4 LY away. How long before you will want to have full
| autonomy, specially given the distance?
|
| - Cultural and political factions - Is it possible that
| individuals in the colony have different objectives, resulting
| with political infighting or open war? What would then be the
| impact on the colony?
|
| - Protection - Depending on technological advancement, how can a
| colony protect itself from external rogue elements (big warship
| gone rogue, pirating the colonies for resources?)
|
| For sure, many of these things depend on the type of species
| colonizing its region, how much sentience and free will they
| have. I also assume they haven't solved FTL travel!
| smallstepforman wrote:
| Well, even if we're not alone, we must acknowledge that someone
| had to be first to develop the ability to travel through the
| cosmos. It may actually be us.
| bagacrap wrote:
| I'd like to think it's at least possible that a life form which
| made it to the stars without blowing itself up is compassionate
| enough to leave Earth the heck alone and treat this system as a
| giant nature reserve. Perhaps they'll swoop in and borrow our
| tech if we ever come up with anything good, just as we might
| draw on the natural world for new medicines or construction
| materials.
| krapp wrote:
| You're assuming a species that practices "compassion" towards
| its own kind would care about us.
|
| Human history is full of examples of societies which treated
| their kin with kindness, but others with cruelty.
| gfodor wrote:
| And yet, over time, humanity has trended to respecting the
| life of all sentient creatures. It seems like in the limit,
| especially if scarcity of resources is eliminated, all life
| will be precious and valued.
| [deleted]
| perl4ever wrote:
| I just googled for how many lab animals are used in
| reseach in the US, and the number was ~800K in 2017.
| _But_ (and this is a big but) rats and mice (and birds
| and fish) are not counted. For some reason, guinea pigs
| and hamsters are considered more equal than rats and
| mice.
|
| _One_ supplier of lab mice in Maine provides ~3
| _million_ mice per year...
|
| Yearly production (and slaughter) of chickens is
| something like _60+ billion_. Not sure if sentient, but
| perhaps they deserve it as descendants of the dinosaurs
| that terrorized human ancestors...
| BerislavLopac wrote:
| We already have that ability. It's just that this travel is
| insanely slow and requires the energy levels that we can't
| easily produce in those timescales. It is quite possible (I
| would even say likely) that any faster travel is not very
| viable, and it might never be possible to make any kind of FTL
| engine.
| alecco wrote:
| We don't have yet the communication technology for anything
| far from our system.
| [deleted]
| jajag wrote:
| Previous discussion on the possibility (mentioned in the article)
| that an advanced industrial civilization existed on Earth:
| https://news.ycombinator.com/item?id=21840320
| hindsightbias wrote:
| Afaik, nobody has debunked the Borra paper, so we already found
| them.
|
| Discovery of peculiar periodic spectral modulations in a small
| fraction of solar type stars
|
| https://arxiv.org/abs/1610.03031
| tokai wrote:
| This study fails to replicate Borra's results.
|
| https://iopscience.iop.org/article/10.1088/1538-3873/aaeae0/...
| hindsightbias wrote:
| Drat! Thanks
| rm445 wrote:
| Discussions of the Fermi paradox get swamped with people's
| individual hypotheses. It's nice to see an article that tries to
| develop a whole different _kind_ of answer. The known
| possibilities seem to be:
|
| 1. We're alone (or very nearly so) due to an early filter. i.e.
| it was vanishingly unlikely for life to develop as far as it has
| here.
|
| 2. We're alone (or very nearly so) due to a late filter. i.e.
| life develops in lots of places but, terrifyingly, it becomes
| overwhelmingly likely to wipe itself out rather than spread.
|
| 3. Life develops frequently but there's some sort of interstellar
| ecology that makes species stay hidden or be wiped out.
|
| 4. Life develops frequently but is overwhelmingly likely to
| develop some other interest (becoming inward-looking, or
| exploring other dimensions) rather than colonising all of space.
|
| This article's suggestion that Earth may be in a backwater
| wouldn't be sufficient by itself, so it is coupled with the idea,
| derived from observations on human colonisation of Micronesia,
| that expansion happens in waves and life on Earth happens to be
| in between waves. The problem is, advanced technological
| civilisations expanding across the galaxy isn't the same thing as
| Polynesian explorers eventually being followed by Europeans. Why
| would the waves die away? This is a late filter with extra steps.
| 8bitsrule wrote:
| 5. No Aladdin's lamp. There's no FLT, no wormholes, no solution
| to the huge distances. And/or interstellar space is so full of
| toxins or plasmas no lifeform can survive it. And/or all EM
| data transmissions are reduced/scrambled/swallowed/encrypted by
| the void. All the experiments are naturally locked in separate
| containers.
|
| 6. _Klaatu barada nichto._ We are indefinitely locked in
| solitary, incommunicado, for creating and using nuclear
| weapons. On ourselves. Immediately.
| lainga wrote:
| I find (6.) somewhat anthropocentric in that it assumes
| nuclear weapons are the _nec plus ultra_ of destructive
| power. You might as well have said in 1917 that we were
| incommunicado for inventing chlorine gas, or shotguns (whose
| use the Germans did object to as a war crime!)
| yborg wrote:
| They aren't. We almost have the capability to do much worse
| ourselves already. If you want big-bang type weapons, you
| can modify an asteroid orbit to drop a K-T event on the
| planet. It's not very target-able, but if you want to try
| and wipe out civilization, it would be pretty effective.
| shawnb576 wrote:
| Yeah (2) seems most likely to me.
|
| Semi-advanced civilization like ours is relatively common but
| almost always depletes it's resources and collapses.
|
| Any civilization needs a lot of energy to grow. Energy is
| generally dangerous.
|
| Climate change and ecological collapse seem to be hard to avoid
| for any civilization wired for growth and advancement.
| ohazi wrote:
| I don't buy this argument. Let's pretend for a moment that there
| are currently 5-20 intelligent species in our galaxy, and
| everyone except us developed deep space ships and successfully
| colonized thousands of other planets (make up almost any numbers
| you want here; the results still hold).
|
| What would our telescopes see? It seems like we would most likely
| see exactly what we see today.
|
| The probability that one of those ships happened to fly anywhere
| close to our solar system, while we were looking, is still
| vanishingly small. Omnidirectional radio transmissions spread so
| quickly that they fall below the noise floor almost instantly
| over interstellar distances.
|
| Space is really really really _really_ big. We can see stars. We
| can just _barely_ see some planets in a few _very_ specific
| configurations. We can sometimes make coarse estimates of the
| chemical composition of those planets. And that 's about it. We
| don't really know how to detect life on extrasolar planets. The
| ones we've already found could be teeming with life and we
| wouldn't know it.
| alecco wrote:
| We might be see them already and not be able to single them
| out. Like the disappearing stars reported recently.
| hoorayimhelping wrote:
| > _What would our telescopes see? It seems like we would most
| likely see exactly what we see today._
|
| We'd see more red than we do - more heat and less light.
| Civilization produces heat. Advanced civilizations would
| presumably convert starlight to energy and produce waste heat.
| pavel_lishin wrote:
| Who's to say that the amount of red we're seeing now isn't
| exactly what you're describing? Maybe if we lived in a barren
| galaxy, we'd see a lot more _blue_, as stars shone
| unencumbered by matrioshka brains.
| phkahler wrote:
| For a simple example, can anyone see Elons Tesla Roadster out
| near Mars? And that's something we know is there.
| ianai wrote:
| https://www.whereisroadster.com/
|
| "A telescope about 51,075 ft (15,568 m) in diameter would be
| required to resolve the Upper stage from Earth. A smaller one
| could see him as an unresolved dot, about 98.2 ft (29.9 m) in
| diameter, in ideal conditions"
|
| So I recon that reinforces the hypothesis.
| Balgair wrote:
| The angular resolution of a telescope scales as the size of
| the diameter of the telescope, essentially [0]. Meaning
| that if you want to image the roadster in visible light,
| you need a telescope lens about the size of Washington DC
| (currently). To just see it at all you need a lens about
| the size of a McMansion.
|
| To image something like the roadster on a Planet orbiting
| Vega (~26 LY away, furthest star anyone on Earth could
| visit and then return from in a lifetime) you're looking at
| lenses greater than the orbit of Pluto, ish.
|
| Optics/Physics is a bitch here. To really see/prove there
| are aliens running about, they have to screaming at the top
| of their lungs for a very very long time, hoping against
| hope that anyone will hear. It's just really really hard to
| build equipment that can passively listen for accidental
| broadcasts and spy on alien cars. At least under our
| current understanding of physics.
|
| [0] http://hosting.astro.cornell.edu/academics/courses/astr
| o201/...
| aruggirello wrote:
| Not necessarily, the apparent magnitude is the issue here,
| not resolving power. Located at a comparable distance,
| Deimos, the smaller moon of Mars, reaches at most magnitude
| ~12.5, meaning that any telescopes smaller than 6" to 8"
| might not even be able to ever detect it's there. And we're
| talking about a 6.2Km sized moon, not an object with an
| overall visible area ~40000 times smaller - that would mean
| an apparent magnitude of ~23-24 as seen from Earth, meaning
| only the most powerful telescopes on Earth would be barely
| able to detect that "unresolved dot" - provided it had the
| same albedo of Deimos.
|
| https://en.wikipedia.org/wiki/Deimos_(moon)
|
| https://en.wikipedia.org/wiki/Apparent_magnitude
|
| Edit: corrected
| aetherson wrote:
| The thing is, why "5-20"? That's a super narrow range. The
| parameters would have to be tuned to a very small degree to
| produce just a handful of technological species in a galaxy.
|
| A much larger range of the parameter-space could produce either
| thousands+ of technological species (which we have pretty good
| evidence is not the case) or less than one on average pretty
| galaxy.
|
| So we have the options:
|
| Lots of species (contradicted by the evidence)
|
| A handful of species (inherently unlikely)
|
| Very few species (current best bet)
| ohazi wrote:
| I think you could increase the guess to 1,000 or 1,000,000
| species and the outcome would still be basically the same.
|
| We _do not know_ how to detect life outside of our solar
| system. The only way our measurements would change is if one
| of them literally landed on top of us.
| aetherson wrote:
| Well, we know how to detect laser and radio transmissions.
| If there are thousands, tens of thousands, millions of
| species out there right now, we've looked at several of
| their stars.
|
| And if there are all these technological species, we would
| expect some of them to be much more advanced than we are.
| Why haven't some of them noticed us?
|
| You can come up with possible answers to these questions,
| it's just that those answers look less likely than, "those
| species aren't actually out there."
| lonelappde wrote:
| Further, think about how powerful a transmission has to
| be in order to not be drowned out by the power of a star.
| A laser would have a far higher chance (yet still hugely
| powerful to cross the distance), but only if aliens found
| us and pointed a laser directly at us.
| sdenton4 wrote:
| Consider that we have, ourselves, gotten far harder to
| detect over the last fifty years. Energy spent
| accidentally sending signals into space is wasted. And we
| are making much greater use of cryptography and
| compression schemes, which would make signals look like
| pure noise.
|
| So, question: how strong does an undirected, random
| signal need to be to be reasonably detected at 10 light
| years away?
| aetherson wrote:
| Yes, that's another example of tuning the parameter-space
| for a possible answer, just an unlikely one. Yes, maybe
| the Milky Way is just chock full of highly advanced
| technological species who have all made themselves very
| hard to detect and none of whom have any interest in
| communications with other intelligent life.
|
| But a simpler explanation that has many more paths to
| being true is "there's nothing out there."
|
| To be clear, I don't think the evidence suggests near-
| certainty here. I wouldn't say that there's a 99% chance
| that we're alone in the galaxy. But it's also not a wide
| open field. There is some evidence, and so far that
| evidence suggests that we're likely alone.
| ohazi wrote:
| I think your assumptions about what is hard and what is
| easy to detect need some recalibrating.
|
| Alien life forms wouldn't need to use technology to make
| themselves harder to detect. It's extremely difficult by
| default.
|
| They would need to use technology to deliberately spread
| a message in a way that is _at all_ likely to be
| detectable, and even then would still have to get quite
| lucky.
| m4rtink wrote:
| Well, that should be just temporary before our real mega
| engineering projects get started. Hard to not notice
| those, even just by the expected heat signatures.
| CoolGuySteve wrote:
| Even more basic than that, why do we think radio/photons
| are the most efficient/effective way to communicate for
| an advanced civilization? Why would they be using them in
| the first place?
|
| We already know neutrinos can travel through most mass,
| so modulating those would let you transmit through the
| Earth and Sun with lower latency and without a repeater
| constellation routing around the object.
|
| Whatever aliens might be using to transmit information is
| likely more advanced than we're able to detect.
| ivalm wrote:
| > Why haven't some of them noticed us?
|
| Maybe they have?
|
| We don't "contact" every pack of deer that we notice.
| aetherson wrote:
| Deer sure as hell know we exist.
| MattRix wrote:
| Ants then. Or even bacteria.
| ivalm wrote:
| Certain deer do, certain deer dont. Also, feel free to
| use a lower animal if that abstraction works better for
| you. My point is that if humans are some out of the way
| primitive life form it might make sense why aliens may
| know of us but not contact us (as in, there may be no
| purpose to explicitly contact us, as humans dont
| generally try to explicitly contact every deer herd).
|
| It is not that humans are technologically primitive
| (which we are), it might be we are too
| intellectually/capacity primitive to be seen as "contact"
| worthy.
| ohazi wrote:
| We know how to detect laser / radio transmissions
| _pointed at us_.
|
| You can't see a laser transmission off-axis if there
| aren't any stray photons reaching your detector - that's
| just physics.
|
| You can't detect a radio signal below the noise floor
| without _some_ a priori knowledge about the statistics of
| the signal.
|
| These aren't justifications, these are simply facts about
| the current limits of our ability to detect far-away
| signals. These limits suggest that millions of far-away
| worlds could be extremely chatty between themselves, but
| unless they decided to point a transmitter at us, we
| would be none the wiser.
|
| You shouldn't use a measurement that looks identical for
| case A and case B to decide which one is more likely.
| ianai wrote:
| I appreciate seeing your comments. The Fermi paradox and
| these similar ideas seem the modern equivalent to
| assumptions the sun revolves around the earth. We need
| more research and infrastructure in this solar system to
| really progress on this.
|
| Imagine if we had thousands of microsats in orbit around
| the various planets that we could triangulate data
| amongst? We need to be more aware of our solar system
| before we can even make reasoned arguments about life
| within it alone.
| wongarsu wrote:
| > before we can even make reasoned arguments about life
| within it alone.
|
| That's an excellent point, for all we know we have
| intelligent, non-spacefaring life right in our solar
| system. It's unlikely, but there's still plenty of
| oceans, gas giant atmospheres and lava tubes that we
| haven't looked at yet.
| pfdietz wrote:
| Why would they stop at thousands of colonies? What is it
| preventing the colonies from themselves creating colonies?
| Also, realize that a colony in the system of another star will
| move away from the originating system. In our neck of the
| galactic woods the rate of separation is typically about 10^-4
| c, so in a million years they'd separate by 100 light years.
| astrobe_ wrote:
| > Why would they stop at thousands of colonies
|
| Why would _we_ stop at a hundred of colonies? A couple of
| observations:
|
| - in rich countries, the trend is that the birth rate is
| declining, the population gets "older". There seems to be a
| link between wealth and birth rate. Even if space conquest
| gives us a lot of resources, if that trend persists, the lack
| of people will be the limiting factor.
|
| - there are only really two reasons to go out: curiosity and
| making sure that a stellar-scale catastrophic event doesn't
| wipe out our civilization. A bunch of colonies "far enough"
| from Sol achieves this. And probably after visiting a dozen
| of systems, the next one will look like one of the previously
| visited.
| akiselev wrote:
| The curiosity aspect might be generational. After growing
| for enough generations, the critical mass of "curious"
| individuals - people who are persecuted, who don't fit into
| the prevailing culture, or who are just really bored -
| might be there for exploring outwards, even if it had
| already been done many time before.
| K0SM0S wrote:
| That's the general story of humanity. From the first
| settlements to the ever-away "final frontier" --
| somewhere between Moon and Mars as we speak. There is no
| doubt in the mind of any historian, psychologist or
| sociologist, IMHO, that we'll probably keep doing this
| for as long as we are "homo sapiens sapiens". That should
| be ~50K years total based on past mutations (iirc? anyhow
| much bigger than recorded history), so I figure we can
| take curiosity for granted as a civilization trait for
| next-gen politics. Like, _lots_ of gens. ;-)
| astrobe_ wrote:
| Since I'm no historian, psychologist, etc. I have always
| believed that great migrations were caused by local
| population pressure - _id est_ too few resources for too
| many people. Even Columbus stumbled upon Americas because
| he was looking for a better trade route.
| K0SM0S wrote:
| That's a reasonable enough assertion!
|
| You could argue that exploration, migrations,
| colonization are but the emergent/complex behaviors
| described by more fundamental principles in psychology,
| sociology, biology. Conway's game of life, in a way.
| History being a mere factual, chronological account -- a
| _log_.
|
| You are thereby operating at a high-level, manipulating
| complex umbrella objects like "great migrations", "local
| population pressure", each of whose words (composite
| concepts) map to lower-level datapoints -- e.g. like some
| eternal tension _(psy., soc., hist., bio...)_ between a
| desire to look inwards _(for security? familiarity?
| survival, support?)_ and a drive to seek outwards _(for
| growth? curiosity? lack, want, need?)_
| Retric wrote:
| The problem with endless expansion is it requires stability
| over very long time scales. Sending a probe to another solar
| system is hardly enough. If you can send a ship say 100 light
| years from your home planet that's 2,000+ repetitions of
| terraforming and colonizing a planet, building up an
| industrial base, then sending ships to every planet in reach.
| Under ideal conditions that might take 10,000 years assuming
| everything went well so you need 20 million years to colonize
| our galaxy. But, assuming everything goes well for 20 million
| years and colonization continues to be a priority seems
| unlikely.
|
| It's very possible to reach a wall where zero teraformable
| planets are within reach of your ships. For large
| civilizations that's unlikely to totally block expansion, but
| it might make the path very convoluted thus increasing total
| time by a rather extreme factor.
| TheOtherHobbes wrote:
| Culture rot will kill you quicker than density of
| colonisable planets.
|
| The transport layer is the easy part. Content integrity is
| a much harder problem.
|
| All of your probes and colony ships have to reproduce the
| source culture - or some viable subservient spin-off - with
| 100% accuracy.
|
| This explicitly means 100% reproductive success of all
| features, especially the politics and economics, with no
| errors.
|
| For a successful colony, stability and conformity have to
| be maintained for long periods - centuries at a minimum,
| perhaps even millions of years.
|
| And of course this assumes the source culture is stable in
| the first place.
|
| Otherwise you're just seeding the galaxy with potential
| competitors, and/or setting up some kind of galactic Battle
| Royale.
|
| I'm bemused by the suggestion the first option is actually
| possible. The second seems more likely, but might not be
| considered a success in the sense of creating a stable
| galaxy-spanning civ capable of common strategic goals.
| mc32 wrote:
| Does intelligence and innovation predict cultural change?
| Is there evidence that this is prevalent in other
| species?
| andrewflnr wrote:
| > All of your probes and colony ships have to reproduce
| the source culture - or some viable subservient spin-off
| - with 100% accuracy.
|
| The only thing that needs to be preserved is the desire
| to build more colonies. I'll grant even that's a stretch,
| but demanding 100% cultural fidelity is silly for
| discussing the Fermi paradox.
| wongarsu wrote:
| Even on earth we had plenty of colonies rebelling against
| the founding nation, gaining independence and becoming a
| serious competitor. Britain might conclude that they
| would be better off today had they never colonized
| America and India. Repeat this pattern often enough over
| millennia and it seems plausible that an entire race
| might become very cautious with forming permanent
| colonies.
| jdsully wrote:
| Britain had to colonize the Americas or France and Spain
| would have without them. It would take another 200 years
| for the empire to fully collapse. It's hard to say
| colonization was a net negative just because of America's
| independence.
|
| Further it seems much less likely the populace would be
| so willing to send aide to Britain during WWI if it
| weren't for the cultural similarities. If instead Spain
| had colonized the US it seems very likely the country
| would have remained neutral as Spain did.
| ben_w wrote:
| Spain did colonise much of what is now the USA. That's
| why it's "Los Angeles" and "San Francisco".
|
| https://commons.m.wikimedia.org/wiki/File:Imperios_Espano
| l_y...
| krapp wrote:
| And Louisiana was French.
| alchemism wrote:
| If human history suggests anything, it would be that at a
| certain point invading other colonies will become more
| profitable than founding new colonies in sub-optimal
| locations.
| Retric wrote:
| Invading another star system of similar technology levels
| without FTL seems like non starter. You could sterilize
| planets, but space based assets are another story and
| retribution is possible.
| mnemonicsloth wrote:
| Yes. Invading ships wouldn't be able to bring a lot of
| fuel/propellant with them beyond what's necessary to
| decelerate from the trip. And they would have to be warm
| enough to support life, so they'd radiate a lot of heat.
| They'd be easy to spot. So no fancy maneuvering and no
| stealth. And the defenders have the resources of an
| entire star system to throw at you.
|
| Terrorism, as you mention, might be possible (but again
| remember, no stealth) and claim jumping (where you
| displace another group that got there roughly when you
| did). But even in densely packed stellar neighborhoods
| the average star is surrounded by a moat several light
| years across. Once the locals are developed enough to
| mount a serious defense, they're probably immovable.
| brlewis wrote:
| > The only thing that needs to be preserved is the desire
| to build more colonies
|
| That's hard. I'd say harder than solving the physical
| problems of interstellar travel. Once a generation has
| learned to live with the limited resources of a starship,
| living with the limited resources of a planet is going to
| be a very attractive option. What's their incentive to
| colonize more from there?
| 3pt14159 wrote:
| In the long run resource shortage goes down. Technology
| increases the amount of output possible for a given
| amount of effort over a given amount of matter. For
| example: wood to coal to oil to nuclear. Thinking about
| starships of 3000 AD we're talking about _a thousand
| years_ of scientific development towards nuclear
| reactors, food processing, scientific computing, and
| random technologies I can 't even fathom because they'll
| rest on a bed of mathematics and physics that's not even
| conceivable yet.
|
| If more technologically advanced aliens exist then our
| not sensing them is much more likely because they don't
| want to be sensed than some other consideration like them
| stopping to setup on some habitable planet. I'm horrified
| about war, and I'd hope they would be too, but it may be
| that aliens come to understand species or ecosystems in a
| more expansive way and may consider the process of ending
| war as a necessary one for the maturation of an
| ecosystem.
|
| Or the great filter is true. We all end up killing
| ourselves because it's impossible to escape exponential
| technology growth and mismatched incentive problems, or
| something else like that.
| dwaltrip wrote:
| It's always going to be a small percentage that desires
| to venture further out to new areas. On a newly settled
| planet, most will not want to leave. But some will.
| brlewis wrote:
| But you have to wait for that society to forget that
| living on a starship means spending your whole life never
| venturing out, while a planet lets you spend your life
| exploring.
| Faark wrote:
| Or, you know, some just want to get away from the other
| individuals.
|
| That is, if we are talking about something comparable to
| current humans. Immortal super AIs might don't care about
| idling in the void for a few million years, just for the
| opportunity to re-sync those gained experiences to their
| decentralized knowledge a few million years down the
| line. I really like the single omnipotent AI scenario,
| since being immortal and not depending on others changes
| quite drastically what strategies can be successful - it
| won't be anything like human kings who need to keep their
| subjects at bay and working for them to support their
| power and limited life. But we shouldn't restrict our
| imagination, if we are talking about possibilities and
| galactic time-spans.
|
| The important part is, as mentioned by GP, the desire to
| expand, since this is a dominant strategy. In comparison,
| not every living being on earth has the drive to
| participate in evolution by e.g. creating offspring.
| Those usually just drop out of the "game" and likely
| won't matter in the long term, at worst making it a bit
| harder for the others initially till their disappearance.
| What matters are those who have persistent impact... e.g.
| by colonizing/making offspring.
| maxander wrote:
| Not just the desire, but also the ability- the cultural
| context for an industrial base potentially far more
| powerful than what we have. That may be extremely
| difficult to sustain over such timescales.
| phs318u wrote:
| > For a successful colony, stability and conformity have
| to be maintained for long periods - centuries at a
| minimum, perhaps even millions of years.
|
| The number one attribute that needs to be preserved is
| the disinclination to blow each other to smithereens. I
| suspect self-destruction (to a level where technological
| progress is setback millenia) is a common enough
| occurrence that would occur well-before FTL becomes a
| possibility.
|
| I also suspect (despite decades of reading SF and my own
| wishes to the contrary), that the kinds of attributes
| that encourage exploration, expansion and risk-taking,
| are also somehow linked to aggression and violence -
| "might makes right".
| pfdietz wrote:
| No, endless expansion does not require stability over very
| long time scales. It just requires that each colony
| produce, on average, at least one successful daughter
| colony. It's not even necessary for the colony to have any
| cultural continuity between when it is created and when
| those descendant colonies are created.
| ohazi wrote:
| I think you could change these guesses to be almost whatever
| you wanted with similar results.
|
| We would not observe anything different unless one of them
| actually flew to our solar system and tried to contact us.
| That's how bad we are at detecting distant life.
| lonelappde wrote:
| I reckon astronomers would find anything that entered our
| solar system and _stayed_ in some solar orbit.
| aruggirello wrote:
| You really mean anything at least _comet /asteroid
| sized_, passing _within the inner Solar System_ with a
| speed and _an albedo_ that would make it stand out
| against the background of stars (reaching at least say,
| apparent magnitude 8-10). Also, note that it should be
| found near the ecliptic plane, to improve the chances of
| detection.
|
| Now, exchange that for a black-ish ship a few hundred
| meters sized, quietly coming from Vega to visit say,
| Saturn. Nobody would probably notice it coming and going,
| despite Saturn being one of the most popular targets of
| the entire sky.
| K0SM0S wrote:
| You'd be surprised how much stuff there is just in our
| neighborhood that we're unable to catch, yet. We mostly
| track dangerous stuff, the big enough - fast enough to
| destroy us, and we now have probably in the 6-7 figures
| objects tracked in the inner solar system. That's it.
| Elusive 9th planets and other major 'quests' are shots in
| the dark so far, mostly -- read accounts on why they
| target some region of the sky, how narrow our
| observational capabilities are as we can only point to a
| very specific direction at a time with each telescope,
| etc.
|
| So, some alien unmanned probe the likes of Voyager in
| large orbit around the Sun? Yeah, no chance in hell we'd
| detect that by random chance, we'd have to seriously
| upgrade our space infrastructure to even pretend
| 'monitoring' our close vicinity, let alone post-Jovian
| space. And we have virtually no knowledge of about half
| the distance between interstellar medium and the Sun,
| that's how limited we are to even modeling the closest
| star systems.
|
| Edit: apparently double-post with aruggirello; I agree
| with him.
| Beldin wrote:
| To underline this point: we shot a red tesla into space
| about 2 years ago [1]. We cannot detect it any more. We'd
| need a telescope with a mirror of 15km to see it. Due to
| uncertainties accumulating, even if we'd had a scope like
| that, we'd probably not be able to point it exactly
| enough.
|
| Oh, and that thing is mostly between the orbits of Mars
| and earth - much smaller search space than "the entire
| solar system"
|
| [1] https://www.whereisroadster.com/
| Aperocky wrote:
| You're very mistaken. We still regularly find 300ft
| boulders in _Earth Orbit_. And routinely find city sized
| asteroid in asteroid belt and state sized minor planet in
| Kuiper belt. Suggesting that a ship can be found as long
| as it's in Solar Orbit is an extremely misinformed
| opinion.
| ohazi wrote:
| True, but without radio transmissions, I bet we would
| spend decades arguing about whether it was actually an
| asteroid and a measurement anomaly. We can't really
| distinguish a rock from a Battlestar at those distances
| without physically flying over to look.
| close04 wrote:
| At this point we're relying almost exclusively on radio
| waves to detect any traces of intelligent life out there.
| So whether they're building moon stations in their
| neighborhood, or sending rockets here and there, we'd
| still look for their transmissions to identify their
| existence and to tell them apart from a random natural
| event.
|
| And while intelligent life may exist on a planet for
| millions of years, their window of actually emitting
| something into the void in a manner we can detect with
| our tech today [0] will probably be a lot shorter than
| that.
|
| This gives us a relatively tiny and limited visibility
| window into the history of life out there. Unless we
| manage to sync our window perfectly with theirs we'll
| never know they existed.
|
| [0] https://www.xkcd.com/638/
| K0SM0S wrote:
| Compounded by the fact that advanced space communications
| would likely rely mostly on laser beams[1], whose
| efficiency and general design fits much better with that
| environment and its infrastructure. Unless pointing
| directly at your instrument (good luck, what are the
| odds?) _and_ missed by the intended receiver, the beam
| will never reach you anyway.
|
| [1] Particularly if your operation is covert, discrete,
| observational, non-disruptive: you'd want to avoid
| signaling your presence in all directions, while wasting
| 99.99% of that energy away from your intended receiver.
| It's just military efficiency, a photon-VPN so to speak,
| that you'd need to "physically MitM" to hack.
| krapp wrote:
| It's entirely possible that a civilization would stop at
| thousands of colonies because, they no longer have the
| technological capacity (having regressed for whatever reason)
| or the desire to continue further. It's also possible that
| the odds against successfully expanding beyond a single
| colony are so great that no one ever makes it to a thousand.
| pfdietz wrote:
| ALL the colonies regress? And stay regressed? Forever?
|
| How is that supposed to work?
| krapp wrote:
| Technological civilizations are fragile - it's more
| likely that they collapse than remain and progress
| exponentially forever.
| merpnderp wrote:
| Is this true? Ours is far less fragile than at any point
| in history. Our only long term threat is nuclear war.
| krapp wrote:
| We're on the edge of a global environmental collapse, and
| most of our civilization's knowledge is being kept on the
| _internet_ of all places.
|
| Also, we were able to land men on the moon 50 years ago,
| and now _that knowledge_ is basically gone, and the tapes
| lost, and people are starting to believe the Earth is
| flat and that the moon landing never even happened.
|
| Meanwhile, we can still read tax records from ancient
| Sumeria because they were carved into clay.
|
| Complex systems are always more fragile than simple ones.
| It seems to me like we've been standing on a house of
| cards for the last century.
| 8bitsrule wrote:
| Our worst long-term threat is our inability to coordinate
| our efforts in order to save ourselves. This test is not
| graded, it's pass-fail.
| pfdietz wrote:
| But your argument requires that all these branches,
| separated by light years, collapse, and then stay
| collapsed forever. The counterargument does not require
| that they progress exponentially forever. They can go
| through cycles, even extinctions, but the remnants can
| pick themselves up and go on.
|
| Your scenario requires a uniformity of outcome across all
| the parts of that civilization, spread across multiple
| stars, and spread across all future time. They all have
| to go down and stay down.
| krapp wrote:
| They don't have to "collapse," merely remain at a point
| of stability that doesn't allow for the energy
| expenditure and infrastructure of interstellar travel.
| That's not an unlikely scenario.
| pfdietz wrote:
| Stability is achieved by having excess capacity, then
| limiting use of that capacity. Societies are not stable
| due to being right up at their limit; such societies
| collapse because of external changes push them over the
| limit.
|
| So, if a stable multistellar society is not building
| colony ships, it's not because it can't, but because it
| has chosen not to. How does that uniformity of choice get
| enforced across time and space?
| close04 wrote:
| There is some point to that. We are perfectly adapted to
| our planet because it formed us. Colonists on another
| planet may not find the same perfect conditions and it's
| likely that even to get a partial match (say Mars like
| conditions) they'd have to be many, many light years away
| from each other, with little outside support. And they'd
| need to adapt to colony ship life first, then to life on
| another planet.
|
| They'd more or less evolve completely independently and
| it's conceivable that having these limitations will mean
| they never reach the same potential as the original
| humans did on Earth.
|
| Usually the comparison with colonists of the past pops
| up. But they had the distinct advantage of being
| perfectly adapted to the planet and many civilizations
| still perished. Seeding another planet with humans raises
| a lot the bar for successfully developing a thriving
| civilization capable of reaching the levels required to
| further spawn successful colonies.
|
| And a philosophical thought: would they even still be
| humans after (tens of) millennia away from the home of
| humanity, in vastly different conditions from the ones
| that evolved us? Would they be "our" thousands of
| colonies?
| krapp wrote:
| I don't believe there is, or can be, such a thing as a
| stable multi stellar society. Barring FTL technology,
| it's impossible to correlate activities or maintain
| coherent relationships when every interaction takes
| years, decades or centuries.
|
| What you have are individual civilizations which may or
| may not, as you mention, decide to invest the time and
| resources into interstellar travel. But that investment
| isn't guaranteed. We've had the technology to send out
| interstellar probes for decades, yet we haven't committed
| to sending them out by the hundreds or thousands. We
| could have colonized Mars or the Moon by now, built Orion
| starships, but we haven't. Technology doesn't govern the
| advance of space travel, politics does.
|
| >How does that uniformity of choice get enforced across
| time and space?
|
| I think it's just a matter of probability. I don't
| believe technological development, much less to the
| degree of having a space program, are an inevitable
| result of intelligence or the presence of civilization.
| It's easier not to have a space program. It's easier, if
| you have a space program, to only explore your own solar
| system. Any number of issues, such as not being near
| enough to a colonizable star, not having sufficient
| energy or resources, natural disaster, giant ants, robot
| uprising, superflu, etc. could keep a civilization from
| starting, much less maintaining, a project of the
| necessary magnitude for the necessary amount of time.
|
| And then you have to survive the trip, and actually
| succeed at colonizing another planet.
|
| I think it's entirely within the bounds of reason for
| every civilization which has attempted interstellar
| travel to have failed up to this point.
| ben_w wrote:
| We don't know how fragile technological civilisations are
| because we've only got one example. It's reasonable to
| say the technological civilisations are highly
| specialised, and it's not unreasonable to suggest that
| excessive specialisation is fragile as we have many
| examples of that in the form of biological speciation.
|
| However, the economic cost of making an interstellar
| colonisation ship is so vast, that from where we are it
| seems reasonable to assume that anyone who does it has
| fully automated manufacturing and resource gathering -
| or, to put it another way, they are post-scarcity. If
| you're post-scarcity, then you're no longer fragile,
| because you can have a complete backup of everything you
| need, including the skills needed to rebuild.
|
| Of course, there's lots of ways for things to go wrong,
| and if I were to imagine badly written control software
| that means the fully automated manufacturing kills
| everyone, I'd be accused of being _too derivative_ rather
| than _implausible_ ...
| Beldin wrote:
| I wouldn't assume that colonies would have anywhere near
| the technical capabilities of the seeding planet.
|
| Just look at what we have achieved in Earth vs. what we
| have achieved on the moon, or anyone's plans for a Mars
| colony. Mankind may set for on Mars eventually, but i
| don't think we'll ever do something like set off
| fireworks there.
|
| Any colony that moves past the immediate survival stage
| is a success. That does not mean they have millions of
| years of fossil fuel stored to start further exploration.
| iso1210 wrote:
| generating methane from co2 and electricity is fairly
| easy, mining helium from jupiter too. Once you have self
| sustaining colony on mars it can colonise the rest of the
| solar system far easier than earth can.
| qw wrote:
| If our technology continues to improve, future humans could
| be looking at life spans of thousands of years if they are
| not killed by accidents.
|
| I assume that it will require population control, because
| we will not be able to find enough habitable planets to
| keep up with the growth we have today. Basically a choice
| of "immortality" or procreation. This will also set a limit
| to how many colonies that are practical to create.
|
| Also some may not accept the risks of travelling to other
| solar systems. Why risk dying "young" when you can expect
| to live for thousands of years?
| m4rtink wrote:
| Well, if you combine these advances even with basic
| artificial habitat building at reasonable scale(Oneil
| cylinders, world houses, covered craters, cavern cities,
| asteroid habitats, etc.) you should be able to house all
| these people quite easily.
|
| If all these long living people dont have to much new
| children (and might not be able to ? eq. if fully
| digitized or with body fully replaced with mechanical
| parts), it might be even easier.
| Magi604 wrote:
| Perhaps slightly off topic, but the title reminded me of this
| picture I took a few years back.
|
| https://www.flickr.com/photos/earlvontapia/16211171391
|
| I really wanted more of the Milky Way to pop out, but was hard
| given the sensor and the lens I was using.
| papito wrote:
| I think it's time we stop looking for life near other stars and
| start saving our own. This planet is completely neglected. You
| want to live on Mars? That should be fun, without a magnetic
| core. Living underground, like rats.
|
| If you want to know what frontier living feels like, take a week
| off and stay in one of the Inupiat villages on the edges of
| Alaska. You'll be climbing up walls in 3 days. And _that_ is a
| luxurious vacation compared to frontier living on a barely
| habitable planet. Netflix? Nah, bro. They still have Blockbuster.
| archeantus wrote:
| It seems to me that the millions of events that happened in order
| to get to where we are now (alive on a rocky, water and oxygen-
| filled planet, in the Goldilocks zone of a healthy star) were
| sequential in nature and they took a finite amount of time to
| occur.
|
| Assuming that there was A Beginning, where everything started at
| the same time, wouldn't the steps to get to where we are in this
| process take about the same time for everyone else? Meaning that
| if there are other civilizations out there, that they'd more or
| less be as advanced as we are? Which is pretty sophisticated in
| certain areas at home, but not yet super capable in the long-
| distance human space travel department.
|
| Not a scientist, just thinking out loud the thought I had reading
| the article.
| peteradio wrote:
| 50000 years ago we were throwing chipped rocks at hairy
| elephants. Technology moves fast on galactic time scales.
| Expecting two alien species to have roughly the same tech would
| be like two randomly fired bullets to collide mid air.
| MattRix wrote:
| There are many stars and planets much much older than ours.
| Earth is 4.5 billion years old, the oldest exoplanet we've seen
| is 12.8 billion.
|
| The terms of the Fermi paradox are are designed to cover things
| like this.
| IAmGraydon wrote:
| Perhaps, but even tiny variances could cause shifts in the
| timeline of thousands or millions of years, which would be a
| blink compared to the age of the universe. Look how far we've
| come in the last 200 years. Imagine a civilization that is only
| 10,000 years ahead of us.
| archeantus wrote:
| I'd love to see what the iPhone 10,000 ends up looking like
| bmdavi3 wrote:
| Does a lion born in a zoo understand it's being held captive by
| (in comparison) super intelligent humans? When it's tranquilized,
| does it know this isn't a normal thing for a lion? When the
| caretaker throws food out or pets it, does the lion have the
| capacity to think about it in any other way than what it means
| right now for the lion - food, feels nice, etc?
|
| If there's a correspondingly more intelligent alien species
| hanging out on our planet with us, would / could we even hope to
| know?
| analog31 wrote:
| Franz Kafka proposes this kind of scenario in "Investigations
| of a dog."
| lordnacho wrote:
| But Lions don't appear to have any abstraction ability, or
| reflective thought. By that I mean you as a human can imagine
| yourself thinking about some hypothetical situation, as well as
| consider what kind of evidence would support a given
| hypothesis.
|
| I think this might have actually happened (apocryphal?), but
| just imagine if you took humans from another country and put
| them in a zoo. They would surely figure it out, based on the
| evidence at hand.
| bmdavi3 wrote:
| Definitely agree.
|
| Just like how a lion or a chimpanzee wouldn't make a
| convincing zoo for another lion or chimp, a human could
| figure out they're in a zoo made by another human.
|
| But when you make a zoo for an animal that isn't on your
| level, you can figure out what's needed to satisfy it (even
| if it's really crappy compared to their normal environment).
|
| So if something smarter than us by an order of magnitude or
| more made a zoo for us, it would be a much more elaborate and
| convincing zoo, and I'm not sure we'd figure it out.
| Syzygies wrote:
| Lions are also unaware of radio waves. We could be unaware of
| self-organizing ripples at the scale of subatomic particles.
| That's a life form that could efficiently colonize the universe
| hitching rides on rocks.
| lifeisstillgood wrote:
| yes.
|
| Edit: Ok. This is a common argument (well apart from the
| "living on earth with us" bit which requires some Doctor Who
| levels of mind-wiping so let's discount that.
|
| Lions see humans in the zoo, and they see the walls of theie
| prison. Lions definitely have had psychological problems in the
| worst run zoos so it is fair to say they are affected and
| aware.
|
| Are they aware of the concept of zoo? Equally unlikely. And the
| next question is how much more intelligent is a human to a
| lion. the answer is not comforting to us as a species.
| bmdavi3 wrote:
| I'm not sure where the corresponding boundary would be
| exactly, since we do seem to be on the verge of exploring
| other planets, but you could say that we also understand
| where it is we're allowed to roam - the surface of Earth. And
| we aren't free of psychological problems.
| nsomaru wrote:
| Interesting philosophical proposition, have an upvote.
|
| It also speaks to the limitations of our senses and the way we
| experience the world.
| lifeisstillgood wrote:
| I would be especially careful of arguments that end up like "it's
| a great opportunity for humankind as no-one else is there to
| compete for the next million years"
|
| It might be true. But the most likely thing we will find on the
| nearest habitable planet is a legal writ and summons.
| zw123456 wrote:
| I have a somewhat nihilistic theory around the Fermi paradox.
| What if all intelligent life annihilates itself before reaching
| high enough technical proficiency to achieve widespread inter-
| planetary travel (or time travel). The idea is that intelligent
| life emerges from the process of evolution (natural selection)
| where the stronger survive. But that leaves you with people who
| have the tendency to kill each other and themselves off. As the
| technological ability to completely annihilate ourselves
| increases the probability that it will eventually happen goes up
| over time. As technological prowess increases and population
| increases, intelligent species eventually destroy themselves by
| using up all their resources or ruin the planet with climate
| destruction before achieving inter-planetary capability. Similar
| to how yeast will reproduce until they all kill themselves off in
| their own waste product (alcohol). It is possible that this is a
| universal axiom, hence intelligent life does not spread across
| the galaxy. I know this is a depressing thought but it's an idea
| that has haunted me once it occurred to me.
| hesdeadjim wrote:
| The models attempt to encapsulate this issue through the
| variable of how long a civilization lasts. As easy as it is to
| imagine civilizations similar to us, it's equally easy to
| imagine others where other variables prevent the intense egoism
| we evolved as a species. Or worlds where competition is less
| fierce perhaps. Etc..
|
| Either way I find it fascinating that we could be living in
| what is essentially the rural area of the galaxy.
| lonelappde wrote:
| With a sample size of 1, there is no way to estimate the
| possibility of a species fundamentally unlike us becoming
| spacefaring.
|
| We can count stars pretty well, but we can only barely
| estimate the probability of an earth-like planet existing
| around a star and forming cellular life.
| yborg wrote:
| This actually was kind of the nugget for me in this story:
| "At one extreme, it is easy to make the galaxy empty by
| simply shrinking the number of usable planets and having
| civilizations last for only, say, 100,000 years or so."
|
| i.e. 10x longer than we have had even rudimentary
| technological civilization on our own planet. Sample size of
| 1, etc. but this to me seems the simple explanation of the
| "paradox". Space is big, and 100k years is a long period of
| time to not make a mistake.
| lonelappde wrote:
| They theory already is shown on Earth. Look how long it take
| humans to get to where we are, compared to how long it would
| have taken if a God had carefully guided us away from
| castrophes like the meteors, plagues, famines, and wars.
| typon wrote:
| This is known as the Great Filter theory
| zw123456 wrote:
| oh thanks, just googled it, I had not heard of it.
| sethd wrote:
| It's described in the article:
|
| > Sounding a more ominous note are concepts such as the
| "great filter"--the idea that there is something that
| always limits a species, perhaps an inevitable failure to
| achieve that green revolution, leading to an implosive
| extinction of all potentially technological life.
| yibg wrote:
| The problem with these types of arguments is they are assumptions
| built on top of other assumptions.
|
| We don't know how to colonize other star systems, so we don't
| really know the factors at play. How easy is it to travel to
| another planet and start a colony? We don't know. How likely is
| it that that colony will colonize other planets? We don't know.
| We are taking numbers we guessed and multiplying with other
| numbers we guessed to get to an answer. If any of them are much
| off the answer doesn't make sense?
|
| What if the amount of resources to successfully travel to and
| colonize a planet in another solar system is so high that the
| vast majority of attempts fail and only a few attempts can be
| made? We can have n (pick some random large number) intelligent
| civilizations in our galaxy and not know a thing about them.
| DubiousPusher wrote:
| My thoughts exactly. I've always found it funny how people
| imply there's some major issue with cosmology because the Drake
| equation shows there should be intelligent life all over. Even
| though some of the terms in that equation are very not known
| and it would only take a few being an order of magnitude or two
| smaller than expected to result in a paucity of intelligent
| life rather than an abundance.
| BerislavLopac wrote:
| I personally subscribe to the school of thought that interstellar
| travel is impossible, except through some form of suspended
| animation or generation ships (which both have its own problems).
| So no warp/hyperdrives, no wormholes, no shortcuts to travel
| between the stars. This article dismisses that notion before it
| even begins, but this is the only theory that fits the currently
| observed laws of the universe.
| m4rtink wrote:
| Even with no FTL, you can still do interstellar travel just
| fine if you make people live longer, which is being worked on
| for other reasons already.
| jcranmer wrote:
| It's not individual lifespans that are the issue, it's the
| lifespan of your equipment. If your rocket breaks down in the
| interstellar void, you have no resources with which to fix
| it.
|
| And then you need to be able to bootstrap the entire
| industrial base to build a new rocket at your destination
| without any help whatsoever aside from what you brought with
| you. Given the history of interoceanic colonization efforts
| on Earth, this suggests that the difficulty ranges from
| "insane" to "impossible."
| m4rtink wrote:
| I think thats stil managable, even simply by redundancy and
| sending fleets of ships. Also 3D printing of replacement
| parts seems pretty promissing and is already being looked
| into (there is a basic 3D printer or the ISS).
| zzzeek wrote:
| the article refers to travel not just by the species itself but
| by machinery that is not limited by lifespan, which in theory
| would also be observable. We have probes that have left the
| solar system through this means. not to mention just the simple
| example of radio waves.
| BerislavLopac wrote:
| The lifespan (either longer human, or mechanical) of
| individual travellers does not affect the speed of
| colonisation, so any communication would be quite limited.
| Which means that there be will be no interstellar "empires"
| or even cultures -- and if any habitable worlds are as rare
| as it seems to be the case for us, I'm not very optimistic
| about encountering any alien species any time soon.
| j_m_b wrote:
| The theory of this article is that we are not just in a gulf of
| space but also a gulf of time. We are after all on the relative
| outskirts of our galaxy, vastly isolated from other
| civilizations. Perhaps one day we'll be the ones knocking on our
| neighbor's door to say hello!
| bena wrote:
| Fermi paradox. I never liked it.
|
| It presumes too much.
|
| It presumes that technology will advance to the degree that we
| overcome the speed of light. Not directly, but that's where it
| has to wind up.
|
| Because no matter how you slice it, it's still four years to
| Alpha Centauri at the fastest possible speed we know. That means
| it will be at a minimum 8 years before we know if anything was
| successful.
|
| And yes, for the travelers, _they_ experience time dilation, but
| we here on Earth would not. That time does matter. Even with
| self-replicating Von Neumann probes, they still have to send that
| information back. That 's still going to take time.
|
| How many resources can you dedicate to a bet that's going to take
| at least a decade to show a return? How many of those bets can
| you make before you've depleted your resources to the degree that
| you simply cannot do it anymore?
|
| I think we may find ourselves up against the uncomfortable truth
| that our cosmic range is rather limited.
| m4rtink wrote:
| IIRC Fermi paradox does not expect FTL - a locust style
| colonization effort should be able to settle the whole milky
| way quite quickly (couple hundred thousand years) even with not
| very fas sub light travel.
| jcranmer wrote:
| It still expects technology that we do not know is possible
| to build.
| bena wrote:
| Like I said, not directly, it doesn't, but once you start
| digging down, you're going to need that.
|
| A couple hundred thousand years is quick on a cosmic scale,
| but we, as a species, have never undertaken any project on
| that scale ever. No species has that we have evidence of.
|
| Any sublight travel is a one way trip with almost no hope of
| ever knowing it was a success by the people back home. No one
| funds that. And I don't blame them. There is no return in any
| fashion for the people who remain. And little to no return
| for anyone who starts the journey. The only thing you can
| possibly satisfy is some minor curiosity.
|
| Travel to Proxima Centauri at the current highest speed we've
| sent probes into space would take over 80,000 years. If you
| double that speed. It will still take over 40,000 years.
|
| So, cosmically, the time scale is short. And compared to
| light, the speed needed is slow.
|
| But we're not light, are we? We don't exist on cosmic scales.
| I'm not concerned with the theoretical limits of physics. I'm
| more concerned with the practical limits of us.
| antepodius wrote:
| Don't be; 'we' won't be doing it. These are
| evolutionary/revolutionary timescales; how many millenia
| away do you think general artificial intelligence is?
| johnwheeler wrote:
| I think if you look at patterns in nature this has to be
| possible. Surely there are some remote ant colonies that don't
| have interaction with anything outside the natural resources that
| sustain them.
| radford-neal wrote:
| The simulations in this article are compatible with the more
| abstract analysis in my paper at
| http://www.cs.utoronto.ca/~radford/anth.abstract.html (see
| Section 7).
|
| The brief summary is that we observe two things: (1) we exist,
| with the full set of memories we have, (2) these memories don't
| include any evidence of other intelligences (I'll assume -
| readers who think they've ridden on UFOs can draw other
| conclusions).
|
| The existence of our particular civilization (in all its detail)
| is more probable if intelligent life is more probable in general
| (assuming one dismisses arguments about infinite universes
| containing all possibilities, so you can never conclude anything
| from anything).
|
| But if intelligent life is generally more probable, it's more
| probable that we have seen other intelligent life, contrary to
| observation.
|
| So the most likely situation given what we observe is a
| compromise - intelligent life is fairly likely (explaining our
| existence), but not really likely, or at least not really likely
| to explore other stars (explaining why we haven't seen any
| aliens).
|
| One unfortunate possibility is that intelligent life reaching our
| technological level is common, but getting to the level of
| colonizing the galaxy is uncommon. But that needn't be highly
| likely. It's also possible that there's other intelligent life
| out there not far away, in which case it may well be within our
| ability to detect it with a bit more effort. That's what one
| would conclude from this article as well.
| [deleted]
___________________________________________________________________
(page generated 2020-01-01 23:00 UTC)