[HN Gopher] Grabby Aliens (2021)
___________________________________________________________________
Grabby Aliens (2021)
Author : noch
Score : 86 points
Date : 2024-02-10 21:03 UTC (1 days ago)
(HTM) web link (grabbyaliens.com)
(TXT) w3m dump (grabbyaliens.com)
| fouc wrote:
| What I found most interesting about this model was the
| implication that humans are possibly one of the earliest sentient
| spacefaring species to have appeared so far. Which explains why
| we haven't seen any other signs of extraterrestrial intelligence
| yet.
| delichon wrote:
| Expecting ourselves to be special has a poor track record. The
| same evidence is compatible with lots of loud aliens yelling on
| channels we can't hear yet.
| distortionfield wrote:
| That's the exact opposite of the grabby alien's hypothesis
| tho. The grabby aliens hypothesis says that we're very much
| average but that life as a whole is still quite young in the
| universe.
| delichon wrote:
| The galaxy is around 100k light years across and 13 billion
| years old. For us to be among the first generation born
| within 10^5 years of each other after a gestation of 10^10
| years, would make us special.
|
| Being among the first civilizations in the galaxy is less
| special than being the first civilization, but more special
| than being just another in an ongoing ecosystem.
| tshaddox wrote:
| Why is being first, or being among the first, "special"?
| To me "special" is different than just "specific." If
| some civilization knew it was the 50th advanced
| civilization in the universe, 50 might seem like a very
| special number, but is it really more special than 1?
| Veserv wrote:
| The hypothesis goes:
|
| I want humans to be casually interstellar and expand
| across the galaxy. I want this to occur in less than N
| years, N << 10^10.
|
| If humans are casually interstellar and expansionist,
| then we would colonize the galaxy in M years, M << 10^10.
|
| Humans are not special, therefore if another alien
| species existed in the past at current human tech levels,
| then they would do the same as humans would and colonize
| the galaxy within N + M << 10^10 years after achieving
| current human tech level.
|
| We believe we can detect such a civilization. Therefore,
| if we are more than N + M years after a another
| civilization with current human tech level, then we would
| see them.
|
| We do not detect any such civilizations.
|
| Therefore one of the assumptions must be wrong.
|
| 1. We can not detect a galactic civilization.
|
| 2. No alien civilization has reached current human tech
| level within N + M years of now.
|
| 3. Humans are special. Only humans would colonize the
| galaxy if they had casual interstellar travel.
|
| 4. Humans are not special, but we will never invent
| casual interstellar travel/spread to the stars.
|
| So, if you think humans are not special (3 is false) and
| you hope humans will spread to the stars in the future
| (hope 4 is false), then you hope the answer is 1 (humans
| are bad at detection) or 2 (humans are early).
|
| If you rule out 1 and 2, then 4 can only be true if 3 is
| true. If you rule out 3 as well, then you must conclude
| humanity will never spread to the stars for unknown
| reasons.
| sevensevennine wrote:
| I don't follow the last point in your argument.
|
| Isn't 4 equivalent to, 'no civilization will invent
| casual interstellar travel/spread to the stars'?
|
| And isn't that hypothesis extremely likely, given what we
| now know about the costs of _interplanetary_ travel and
| its relative ease compared to interstellar travel?
|
| That's another assumption, that it's _possible_ to
| colonize a galaxy from a planetary base. We don't even
| know that it's possible to colonize a nearby planet. If
| we were confident that we could, we'd be filling up
| Siberia, Ellesmere Island, and Greenland first.
|
| There's also another assumption missing from your list-
| that technological civilizations can last long enough to
| colonize the galaxy. I'm also surprised that there isn't
| any discussion on the site or here of Great Filters. If
| the average technological civilization wipes itself out
| within a few hundred years of developing technologies
| that enable space travel or even radio, then all
| discussion of "filling the galaxy" is castles in the air.
| eschaton wrote:
| It also could be that interstellar travel is possible but
| never inexpensive enough to be casual or useful for ever-
| expanding colonization. Or it could be that civilizations
| stabilize before the point where ever-expanding
| colonization becomes attractive.
|
| As an example of the latter, look at birth rates in
| different societies on Earth: Almost universally, they
| decline to replacement level once they hit a certain
| level of per-capita wealth.
|
| It's very likely that a society that achieves
| interstellar travel will do so _after_ it achieves the
| ability to provide the highest standard of living for all
| of its members indefinitely using just the resources of
| its local system. This already describes Earth; the
| reasons we don't do this are ideological, not based on
| any inherent constraints, while interstellar travel isn't
| in our grasp yet and is likely to be extraordinarily
| costly.
|
| Such a society wouldn't face any pressure to grow, so any
| colonization would itself likely be ideological--"We
| don't want to do things Surak's way, let's pull up stakes
| and find a world where we can live the way we want!"--or
| as a contingency/hedge against large-scale existential
| risk. Neither demand colonizing even a small fraction of
| a galaxy, assuming habitable worlds are even remotely
| plentiful near and reachable from the origin world.
| Veserv wrote:
| You have missed the point. The goal is humanity becoming
| Star Trek and enclosing every star in a Dyson Sphere; the
| goal is determining whether 4 is true or false. The
| question is what is stopping it. The entire point of
| these thought exercises is setting up proof by
| contradictions/falsifiable experiments to narrow that
| down.
|
| Maybe (4 is false) is inevitable now that humanity has
| reached its current point. Maybe literally every human-
| like species will become Star Trek and enclose every star
| in a Dyson Sphere; that would be awesome since it means
| our goal is now a foregone conclusion. But how would we
| know? Well, we can do a thought experiment assuming it
| and extrapolate toward characteristics that we might be
| able to detect to falsify our hypothesis.
|
| Well if literally every human-like species will enclose
| every star in the future, then we should not be able to
| see any stars at some point after one comes into
| existence. We can still see stars, therefore either it
| has not happened yet (1), there are no other human-like
| species (2), or the supposition is false (3). If the
| supposition is false, then there are risks ahead of us.
| If the supposition is true, then the risks are behind us,
| but then (1) or (2) must be true. For (1) to be true, we
| must either be early or it takes a long time. For (2) to
| be true, we must either be early or rare. If we can rule
| out (1) and (2), then we must conclude (3) which means we
| can be confident that there must be a risk ahead of us
| preventing us from reaching our goal that we as a species
| need to be wary of even if we do not know what it is
| specifically. We just know it has to exist otherwise we
| would see no stars.
|
| If (1) or (2) is true, then (3) no longer needs to be
| true. It might still be the case that the goal is
| impossible, but at least we have a chance. The point of
| this analysis is trying to theorize where we need to look
| that gives humanity the most information about if and how
| to become Star Trek. It is not about coming up with the
| "correct" answer; we do not have enough information for
| that. We are trying to create theories that take facts
| that we can find (or can in theory find) as inputs and
| generate predictions that can be tested and falsified.
| pfdietz wrote:
| > And isn't that hypothesis extremely likely, given what
| we now know about the costs of _interplanetary_ travel
| and its relative ease compared to interstellar travel?
|
| Costs are a function of manufacturing productivity. What
| is the upper bound on manufacturing productivity? With
| automation and AI, I don't see any hard upper bound.
|
| The raw resources are certainly available to build
| starships. I mean, your share of per capita energy
| consumption over your life would be enough to accelerate
| your body to maybe 700 km/s, and that's with us just
| using a small fraction of the energy available on a
| planet; energy in space would be many orders of magnitude
| more abundant.
| 7thaccount wrote:
| Just gotta turn on that subspace receiver and get cosmically
| rick-rolled :)
|
| It is one idea anyway. It would be bizarre for us to end up
| some precursor species...at least in our galaxy.
| actionfromafar wrote:
| _Barely_ spacefaring. We are like fish on the shore who can
| survive in the mud long enough for the tide to come back to
| rescue us, if that.
| morkalork wrote:
| That's a pretty good comparison. We go to space but it's a
| fleeting excursion so far and we haven't yet evolved the
| necessary abilities to make it permanent
| Charon77 wrote:
| If a planet in the nearest star harbors life form that
| launched a rocket, would we know?
| cryptoz wrote:
| No, we wouldn't know today. But this is knowable in about
| 50 years or so, if we send probes to ~550AU and use the
| Sun as a gravitational lens; we will then be able to get
| high-res (1km resolution?) photos/videos of nearby
| extrasolar planets themselves. This may be enough to find
| a spacefaring civilization. (sure, rockets aren't 1km
| big, but they do leave big traces. maybe we could see
| that)
| Qem wrote:
| > if we send probes to ~550AU and use the Sun as a
| gravitational lens; we will then be able to get high-res
| (1km resolution?) photos/videos of nearby extrasolar
| planets themselves.
|
| It doesn't scale well. The probe would be able to observe
| a carefully chosen extrasolar planetary system in the
| opposite direction in relation to the sun. If you want to
| observe a second system, it's necessary to launch a
| second probe 550 AU in another direction. You can't
| change targets just by rotating the probe, given its lens
| is the sun.
| cryptoz wrote:
| Oh yeah, I'm aware that you'll need multiple probes - but
| I imagine we could send 50 or 100 of these things
| starting in like 20-30 years once some of the required
| engineering on propulsion systems etc is done. Assuming
| we have the will and money to send 1, I think we'd have
| the will and money to send dozens.
| defrost wrote:
| As Qem mentioned, and as laid out on page 7 of the source
| paper: A significant difference of the
| solar gravitational lens from a conventional telescope is
| that the gravitational lens telescope is not in any
| practical sense pointable. For the telescope
| at a distance F from the sun to be re-aimed to image a
| new target 1deg away, it would have to move a distance of
| (p/180deg)F, which is 10 astronomical units at the
| minimum focal distance-- a lateral distance equivalent to
| the distance from Earth to Saturn. This
| means that, in practice, such a telescope is not able to
| be repointed. Thus, a telescope at the
| gravitational focus is necessarily going to be a
| singlepurpose telescope, with the target of observation
| selected before the mission is launched. A
| gravitational focus mission can't be used as a telescope
| to search for a target: such a mission must be with the
| objective to observe a target whose position is already
| known.
|
| _Mission to the Gravitational Focus of the Sun: A
| Critical Analysis_
|
| Geoffrey A. Landis, NASA John Glenn Research Center
|
| https://arxiv.org/ftp/arxiv/papers/1604/1604.06351.pdf
| p1mrx wrote:
| That seems like a good match for this nuclear sail
| concept:
|
| https://www.nasa.gov/general/thin-film-isotope-nuclear-
| engin...
|
| > The basic concept is to manufacture thin sheets of a
| radioactive isotope and directly use the momentum of its
| decay products to generate thrust.
|
| Actually it's mentioned at the end of the article:
|
| > Novel ability to reach deep space (> 150 AU) very
| quickly and then continue aggressive maneuvers (> 100
| km/sec) for dim object search/rendezvous and/or
| retargeting telescopes at the solar gravitational focus
| over a period of years.
| zarzavat wrote:
| That's just because our neighbourhood is so boring in
| comparison to Earth.
|
| Imagine that by some chance Mars was another Earth with a
| breathable atmosphere. NASA would have been given a trillion
| dollar budget and we would have been there in the 80s.
| Instead it's a dead red rock so NASA gets a small budget and
| the US spends its money on blowing people up instead.
|
| We have the technology to be a spacefaring civilisation but
| we won't care until Earth becomes a worse place to be than
| the rest of the solar system, which is probably never given
| how bad the other bodies in the solar system are. Most likely
| we develop Von Neumann probes before we ever get bored of
| Earth.
| XorNot wrote:
| I do keep hoping we get lucky in my lifetime and a massive,
| water bearing comet with slam into Mars and jumpstart the
| terraforming.
|
| Watching a planet which could retain water go from "nothing
| to oceans" would be amazing.
| lostemptations5 wrote:
| Evidence suggests Mars had oceans before and they just
| evaporated due to the thin atmosphere and non-existant
| magnetic field no?
|
| I'm not sure how that would get solved without some
| active technological solution by humans let's say.
| XorNot wrote:
| Over a timespan of hundreds of thousands of years.
|
| Which is short in geological terms, but an eternity in
| technological ones. We would have plenty of time to solve
| that problem.
| mjevans wrote:
| I'm not sure which is more practical. Diverting enough
| material to replicate earth's natural magnetic core
| system on mars into the planet, or building an artificial
| system. The knowledge gained from attempting either is
| likely valuable.
| ben_w wrote:
| Synthetic magnetic field is much easier than messing with
| the planet's core. Put a relatively small power plant in
| the Sun-Mars L1 point, and attach to a big conductive
| ring: https://phys.org/news/2017-03-nasa-magnetic-shield-
| mars-atmo...
| marcosdumay wrote:
| Fucking journalists publish an article with magnetic
| dipole measured in Teslas... So I go to the linked paper,
| and it has basically the same contents, on basically the
| same wording, with the magnetic dipole measured in
| Teslas.
|
| It appears that at some point, somebody involved with
| this knew what they were doing. But we are removed so
| many steps from that person, that anything said there
| could as well be Star Trek techno-jumble. Including the
| conclusions.
| echelon wrote:
| > implication that humans are possibly one of the earliest
| sentient spacefaring species to have appeared so far.
|
| Or that perhaps we're a simulation.
|
| We exist in a very interesting time in history when the pieces
| are coming together.
|
| Our hypothetical future robot descendents may be very
| interested in learning about their past.
| ionwake wrote:
| i dunno bros, but this is the explanation of the fermi
| paradox for me. Sorry to go all HGTTG but...
|
| >Wake up
|
| >No idea where I am
|
| >Hey we have no idea where everyone is
|
| >According to history nothing much has happened in the
| universe
|
| >Oh look at that, just now that you are alive you are hitting
| the singularity
|
| Feels a little like a rehashed sitcom episode...like a
| director is just brute forcing shit to figure out a solution,
| with our lives. And its all probably just on how to make a
| good cup of coffee for his interdimensional space ship.
| kiba wrote:
| We wouldn't know if we're in a simulation unless the
| diety/programmer wanted us to know that.
| ionwake wrote:
| Not really I disagree.
|
| With software that encourages emergent behaviour we are
| unaware of the abilities the entities take on. So in theory
| I think we could.
| kiba wrote:
| They can just simply pause, delete, reverse, or make us
| outright ignore anything. They are literal god and hold
| ultimate power over us, unless they are willing to
| deliberately let things happen.
|
| The better question is if it even matter.
| ionwake wrote:
| Im sure it matters, or else we wouldnt exist. How "much"
| we matter is the question.
| saghm wrote:
| How would you know? Based on what we know of simulations in
| this reality, which has rules designed by whoever created
| it? If you're programming a simulated universe and don't
| want its inhabitants to know, it seems like a pretty
| obvious mechanism to try to enforce that would be to make
| the rules so that it seemed like "leaking" information into
| a simulation was impossible, even if the rules of their
| "outer" reality made it impossible for them to fully
| prevent it, only dissuade us from looking into it.
|
| This is kind of why I mostly find the discussion of whether
| we're in simulation to pretty quickly reach a point where
| it stops being interesting even from a philosophical
| perspective. I don't really see how you can differentiate
| between fundamental properties that we observe that reflect
| the "real" universe where we're just a simulation and
| fundamental properties that explicitly designed for the
| purpose of the simulation itself and may not actually
| reflect the "real" universe. We might as well ask if the OS
| our simulation is running on has a toggle for dark mode or
| not.
| kiba wrote:
| There's no test that can make us convince ourselves that
| it's a simulation or not. The real question is if it even
| matters. We are just as real if we're not a simulation,
| or are a simulation.
| hotpotamus wrote:
| If we're in a simulation, there's no reason that other beings
| couldn't have also arisen within the simulation with us.
| lostemptations5 wrote:
| Or that they are also in a simulation.
| Kostic wrote:
| Spacefaring is very generious. We still have to make a trip
| between two planets, not to mention two stars.
| distracted_boy wrote:
| We have seen signs, they were called UFOs but are called UAPs
| now, at least by the US government. People have tried coming
| forward over the years and talk about the subject, but was met
| with ridicule.
|
| I suggest googling David Grusch to read about the whistleblower
| from inside US intelligence services. Also search for "Navy
| Rear Admiral Tim Gallaudet ufo" and you'll find additional
| comments.
|
| This is the greatest coverup in human history.
| ben_w wrote:
| Such conspiracy theories amuse and confuse me in equal
| measure.
|
| Do you also think North Korea, Cuba, and Iran either don't
| exist or want to be part of this coverup? Do you live in a
| world where there's really only one government and any
| indication to the contrary is mere kayfabe?
| chad_stephens wrote:
| I'm sure they do, and for all we know may Iran is part of
| the conspiracy. Cuba and NK are small fry and are probably
| excluded.
|
| In the lore, multiple governments are involved in the
| conspiracy. They keep it secret because it is a race to see
| who can crack the alien tech the fastest.
|
| There have been cases in the lore of other countries
| (Brazil and Zimbabwe i believe) having encounters or
| alleged down aircraft and the US has came in to
| investigate/recover the down object.
|
| I don't think there is a world government, but i do think
| we cooperate with each other.
|
| Also President Clinton says he tried to get information on
| UFOs but they refused and gave him the runaround.
| shrimp_emoji wrote:
| Our ability to detect signs of ETI is very limited. It could be
| all over, and we could have even detected it already, but we
| don't realize it. Studying up on astrophysics (how we detect
| and transmit signals, how signals attenuate and fade over
| cosmic distances, and some of the signals SETI has already
| received) reveals that.
|
| The Fermi paradox is only a paradox due to the assumption that
| in a few million years a civilization will colonize the entire
| Milky Way just because it's theoretically possible, so we
| should be up to our eyeballs with aliens' von Neumann probes.
| But many things are theoretically possible. We could build the
| world's largest house -- the size of Nebraska. Every nation
| could reorient and sink their economy into that megaproject and
| do it. But it's irrational to; there's better things we want to
| do with our resources (which will always be finite, all the way
| up the Kardashev scale). That's why I think it's silly to
| expect any intelligent life to be that ambitious (or
| competent).
| Arch485 wrote:
| I might be missing something here, but why would alien (or any)
| civilizations continually expand at a constant rate?
|
| While I'm not an expert, it appears that by observing life on
| Earth (not just humans), groups of living things do not expand
| linearly, and eventually hit an upper limit (this happens at all
| scales, from colonies of bacteria to entire civilizations).
|
| Who's to say that other "loud" aliens haven't already expanded
| and begun spacefaring, but simply are not expanding out to where
| we are?
| LoganDark wrote:
| Based on human history, wouldn't the rate of technological
| growth eventually start to skyrocket during/after some
| revolution? And with better technology comes better/more
| expansion.
| Ancapistani wrote:
| So far, it seems like the Industrial Revolution was the key
| accelerating factor for our civilization. Conditions for it
| were right (or very close) at the height of the Roman Empire.
| They were probably pretty close at the height of Chinese
| power, and the Islamic world before the Khans.
|
| ...but we're still a young civilization, and are
| extrapolating from very little data. It could be that we've
| yet to encounter most of those inflection points. Maybe the
| next one is "the Singularity" - but beyond that we really
| have no idea.
|
| All of this is consistent with humanity being very early on
| the timeline of the universe.
| LoganDark wrote:
| What I know is that technological progress was very slow,
| until suddenly there was a breakthrough and it rapidly
| accelerated. Now, we have enough of the fundamentals down
| that new technological breakthroughs are happening
| extremely rapidly. What a time to be alive, of course, but
| what suggests alien civilizations wouldn't follow the same
| trend of rapid acceleration rather than constant growth?
| geor9e wrote:
| Constants are the simplest assumption. It's a "first round" of
| modeling that lets you start having philosophical thoughts on
| the implications. You can always increase the complexity of the
| model after. If you don't hold some parameters constant, the
| model quickly becomes too complex to be of much use for
| philosophical questions. In reality, a civilization can expand
| with exponential acceleration, deceleration, or shrink. I
| didn't even think this the worst of the assumptions. The fact
| that expansion stops as soon as a civilization meets another
| seems silly too. As we know, civilizations love nothing more
| than respecting borders and not conquering each other. But
| again, it can go either way, so they chose the middle
| assumption.
| ben_w wrote:
| Fastest growing subpopulation rapidly dominates the whole
| group.
| tshaddox wrote:
| Aren't you essentially just describing a Great Filter, which is
| one of the classic proposed solutions to the Fermi paradox?
| FrustratedMonky wrote:
| I think that is mentioned in some of the materials.
|
| This 'grabby' alien and 'light cone' discussion is explaining
| , or one solution to the Fermi Paradox.
| Udo wrote:
| > Who's to say that other "loud" aliens haven't already
| expanded and begun spacefaring, but simply are not expanding
| out to where we are?
|
| By definition if they're loud and we can't see them, they're
| not within the volume of our visible universe.
|
| > I might be missing something here, but why would alien (or
| any) civilizations continually expand at a constant rate?
|
| This assumes they keep multiplying and colonizing outward.
| There is no real upper limit - except, eventually, the
| accelerating expansion rate of the universe that keeps them
| from reaching further. Because the colonized volume is so
| large, we don't really assume these colonized volumes form a
| coordinated empire. It would be more like a loose tangle of
| city states spread across a vast landscape. They might share
| common heritage, technology and some amount of culture, but be
| otherwise independent.
| pfdietz wrote:
| > Advanced aliens really are out there
|
| Stopped reading right there.
| behringer wrote:
| You're missing out then. That's the assumption being made in
| the paper and they take it as far as they can while sticking to
| some semblance of reality. Very interesting ideas in here.
| GavinB wrote:
| This is a compelling theory, especially the implication that
| humans are early. I do wonder whether we should see the evidence
| of spheres of growing alien influence out in the stars, but
| instead we see a highly uniform universe in all directions.
|
| This would indicate a few possibilities:
|
| 1. Expanding alien civilizations are relatively low impact and
| don't collect all of the energy of stars in ways that are visible
| to our current telescopes.
|
| 2. We are a very early civilization, civs are fairly rare, and
| we're relatively alone in the parts of the universe that we can
| see. Civs that are expanding in a grabby fashion started less
| recently in years than their distance in light years.
|
| 3. Aliens expand at close to the speed of light, so there are a
| lot out there but we won't see them until they're almost here.
|
| 4. Something that we have already noticed is actually evidence of
| grabby aliens, but it is happening in every direction so we
| assume that it is a natural phenomenon, because it is so uniform.
|
| At the very least, it seems likely that we either we are alone in
| the galaxy, or expansion is very slow. The idea of "expanding in
| a bubble of influence close to the speed of light" seems
| implausible to me, just because of the vast amounts of energy
| required to accelerate and decelerate to relativistic speeds, not
| to mention protecting the cargo in transit--when you're flying at
| .9c, almost every other piece of matter in the universe is flying
| towards you at you at .9c. Accelerating tiny nanomachine von
| Neumann probes might be a solution, but how would they decelerate
| enough to not be destroyed on arrival?
|
| It's all fascinating to think about, at least.
| taneq wrote:
| > how would they decelerate enough to not be destroyed on
| arrival?
|
| Solar sail being pushed on by the destination star? Or to begin
| with, even just a "drouge" creating friction against
| interstellar gas?
| Matt_Mahgerfteh wrote:
| Yeah, it's like we're playing cosmic detective trying to figure
| out if there's anyone else out there in the universe. The fact
| that we haven't seen any clear signs of alien civilizations
| doing their thing is kind of mind-boggling. It's like, are they
| just really subtle about it, or are we just super early to the
| party?
| 7thaccount wrote:
| Or if there is some dark foresting going on or one of a dozen
| other theories
| throwawayqqq11 wrote:
| When you mine asteroids in orbit on a large scale around your
| star, the released dust/debris would form an IR halo around
| the star that would be very easy to detect and reveal your
| presence but we dont see any of it.
|
| So, early humans it propably is.
| ccheney wrote:
| Your point on missing IR halos is valid, but don't overlook
| anomalies like Tabby's Star (KIC 8462852) [0]. Its odd
| dimming led to theories about alien megastructures like
| Dyson Spheres, though dust or comets are possible
| explanations. Still, Tabby's Star highlights the difficulty
| in excluding advanced alien activities with our current
| tech. [1]
|
| [0] https://en.wikipedia.org/wiki/Tabby%27s_Star
|
| [1] https://youtu.be/mZve2Oy3cFg?t=82
| matthewdgreen wrote:
| This person [1] ran a data search for stars with a
| similar light profile ("slow dippers") to
| Tabby/Boyajian's Star, and claims to have found a cluster
| of similar stars in the region. But the results are not
| particularly high confidence and are probably just data
| artifacts.
|
| [1] https://iopscience.iop.org/article/10.3847/1538-3881/
| ac3416
| exe34 wrote:
| Would you pollute your environment with missiles at orbital
| speed? I suppose given our stellar stewardship of the
| atmosphere, maybe they're like us.
| throwuwu wrote:
| I don't think we're going to build rock crushers in space.
| With all that available energy it'd make more sense to just
| throw the whole rock into a smelter and fractionate the
| elements as they boil off. Why waste the slag either? You
| need all the material you can get so hang on to it and use
| it as ballast or extract the carbon and silicon from it.
| It's more likely that we don't see waste because there
| isn't any, a dollar saved is a dollar earned.
| AnimalMuppet wrote:
| Aliens collecting all the light/electromagnetic radiation from
| stars would be an interesting way to get dark matter. That's
| one place it could fit.
|
| And, if our theories are right, we're at 4.9% regular matter
| and 26.8% dark matter, so dark matter is five times as much as
| regular matter, so that's a _lot_ of aliens...
| bhickey wrote:
| What you're suggesting doesn't make sense.
|
| Dark matter isn't non-luminous matter. It's matter that only
| interacts gravitationally, but not electromagnetically. This
| means it doesn't undergo collisions and can't shed angular
| momentum. It forms a diffuse, largely uniform cloud
| throughout galaxies. The result is that galaxies are more
| dense further from the galactic core than we would predict
| from luminous matter alone.
| bqmjjx0kac wrote:
| I'm speaking outside my area, but dark matter is not really
| confirmed to even exist?
| bhickey wrote:
| It's consistent with observational evidence. You are
| correct that no one has detected dark matter particles.
| revscat wrote:
| https://youtu.be/nbE8B7zggUg?si=QcBpuxSvXsGGxTKk
| tsimionescu wrote:
| It's clearly confirmed that galaxies don't obey the known
| laws of quantum electrodynamics (QED) + general
| relativity (GR) if we assume they are made entirely of
| Standard Model particles. So, either QED is wrong
| (extremely unlikely) or GR is wrong (unlikely) or there
| is some matter that is not in the Standard Model
| (plausible).
|
| Dark matter corresponds to option 3 - and there are
| observations that conform some models of dark matter
| distribution that match quite well between different
| galaxies. There are other theories as well, such as MOND
| (modified Newtonian gravity) that explore option 2 (GR is
| wrong).
|
| Still, whatever the theory, it's clear that what is _not_
| happening is "aliens someone consuming all of the EM
| radiation from some stars". With anything resembling
| currently known physics, it's impossible to "consume" EM
| radiation in this way. Electric charge is always
| conserved, electrons and quarks don't disappear just
| because they move around, even with something like
| controlled fusion. A Dyson sphere would be an extremely
| hot visible object, not some dark point.
| ben_w wrote:
| > So, either QED is wrong (extremely unlikely) or GR is
| wrong (unlikely)
|
| Not my area, but I thought both were known to be
| incomplete? Q because it presumes a flat spacetime; R
| because it predicts the formation of singularities that
| the maths used to develop it assume don't exist?
| tsimionescu wrote:
| I think the general belief is that it will turn out that
| space time is actually approximately flat at small
| levels, so that QED will be essentially exactly correct,
| while GR will turn out not to apply past a certain small
| scale.
| FrustratedMonky wrote:
| Wasn't the term 'dark matter' just meant to indicate
| 'unknown'.
|
| It wasn't meant to be descriptive, just that there is a
| gap between theories.
|
| And one theory is there is some 'unknown' type of matter,
| and they called it dark.
| bhickey wrote:
| No. 'Dark' comes from 'dunkle' in German. It refers to
| non-luminous matter.
| throwuwu wrote:
| What if they're really greedy about energy and store
| everything they can in superconductors?
| tsimionescu wrote:
| Superconductors still have an EM signature, they still
| have magnetic fields around them and are detectable.
| bhickey wrote:
| > Dark matter isn't non-luminous matter.
|
| What I meant to write is--
|
| > Dark matter isn't merely non-luminous matter.
| c22 wrote:
| I like option 4. Perhaps some of the things we think are black
| holes are just grabby aliens.
| therockspush wrote:
| Who knows what they've been grabbing.
|
| https://www.youtube.com/watch?v=u5qYH-Y3tQ4
| cwillu wrote:
| Alas, there's a fifth possibility:
|
| 5. Controlled transportation between the stars, sufficient for
| colonization, is sufficiently impractical that there are no
| grabby aliens within our light-cone.
| XorNot wrote:
| That itself would be quite interesting though, because based
| on what we know now it's merely difficult, not impossible
| with reasonably foreseeable technological improvements.
|
| The dynamics which would make it _impossible_ on any known
| timespan don 't seem currently observable.
| whizzter wrote:
| I think a huge factor you don't account for here is that
| some of these technological improvements might imply a
| great-filter that we really haven't passed yet as humans,
| and the negative effects would affect most similarly
| expansionist and competitive races alike us since it might
| be questionable if there would be enough pressure on a non-
| competitive race to expand rather than just conserve local
| resources.
|
| Just with state-controlled nuclear weapons we've been on
| the brink of extinction a couple of times already, the
| energy levels required for star-travel implies this kind of
| destructive power being in the hands of even more people
| (and by necessity more or less out of control of the nation
| states). A commercial airliner took down WTC, a starship
| would be an WMD capable of taking out a city (or more).
|
| One implication of this is that there's a chance that we've
| already invented practical fusion power, but if it's
| trivial to miniaturize AND weaponize then people in control
| of it have decided to withhold it to avoid every weird
| terrorist group creating one.
| scotty79 wrote:
| Maybe all roads to space travel lead through global
| dystopian panopticon and police state?
| throwuwu wrote:
| You might want to check the physics on your assertion
| that a starship could take out a city. It'd have to be
| designed to do so otherwise it would just vaporize as it
| entered the atmosphere at the velocity you'd need for
| that kind of impact.
| whizzter wrote:
| I haven't done any calculations (since we don't have any
| feasible crafts for interstellar travel that's irrelevant
| really), but considering it for a few minutes I'd say
| there's 3 increasingly likely ways around that.
|
| 1: Considering the amount of rocket fuel we need to leave
| earths atmosphere and reach the Moon, people have been
| proposing nuclear rockets to reach Mars. That's still
| within the solar system, reaching another star requires
| magnitudes more energy, even more so to accomplish enough
| acceleration to reach another star within a persons
| lifetime. Such a mode of energy generation not having an
| explosive failure more feels unlikely (thus making it
| blow up in a dock is enough).
|
| 2: Barring option 1, reaching fractional light speeds,
| would not a ship need enormously more capable shields
| than anything today to safeguard humans? The Tunguska
| event(3-5 mt) was at "just" 27km/s of a 50 meter object.
|
| 3: Speaking of Tunguska, even if the ship itself would
| lack such shields (however a human would be expected to
| survive w/o one), a ship capable of interstellar travel
| should be able to push out a rock and then accelerate it
| back to earth to create a Tunguska (or larger) event at a
| target location.
|
| The core issue is the energy levels required(1),
| converting them to something destructive is usually
| within grasp of less intelligent people than those that
| research the advances that make them available.
|
| 1: https://www.sciencedirect.com/science/article/abs/pii/
| 009457...
|
| TL;DR; quotes 10^20 joules of energy, as the article says
| equivalent to complete fissioning of 1000 tons of
| Uranium.
| throwuwu wrote:
| If we're talking specifically about interstellar craft
| with enough shielding to survive an uncontrolled reentry
| at high velocity then what the heck are those going to be
| doing near a planet? Sublight travel would have to be
| performed by craft large enough to support the crew for
| years if not decades or generations. You're not going to
| want to maneuver that much mass into orbit around a
| planet. They'd be better off parked in a trojan orbit and
| letting smaller craft move people and supplies back and
| forth You might as well try to hijack an aircraft carrier
| and fat chance of surprising anyone if you could pull it
| off.
|
| To get a ship to hit the ground at the velocity you're
| talking about a large chunk of it would need to be solid
| steel like a bullet basically. Space craft aren't built
| like that, they need to be mostly empty space for storing
| propellant and people. A reactor and its shielding might
| survive but that's on the scale of 5 - 10 meters and it's
| still not 100% solid so it doesn't compare to a large
| metallic asteroid.
|
| Throwing rocks at a planet might work but you need the
| right equipment and expertise to bullseye a planet from
| 100 million miles away and if anyone saw you do it they
| could take their time intercepting the rock.
| SV_BubbleTime wrote:
| We barely knew about flight in air, or germs on hands, sent
| even small objects in to space in extremely recent history.
|
| Hand waving away "we can't travel through stars" because we
| currently don't get it, seems like the weakest way to
| discuss the topic.
|
| You/we can't imagine it; so it must be impossible or in
| practically difficult? What if it turns out to be extremely
| easy, we're just extremely small or extremely
| uninteresting? Those are far more likely topics than we
| already have the answers and have decided it's not
| possible.
| throwuwu wrote:
| If you assume FTL travel will never be developed then
| distance and time are simple limiting factors. How do you
| keep a cohesive civilization going when communication takes
| 200 years? Or even just 20? Here on Earth entirely new
| languages and cultures arose across distances that wouldn't
| even cross a state line when communication was limited to a
| small handful of travellers and merchants. Any colony
| further away than 5ly would quickly diverge. I'm pulling
| that number out of my hat but I'm sure you could figure out
| the effect of time spent in journey on willingness to
| travel. Not many people would commit significant chunks of
| their lives to interstellar business trips. Radio
| communications won't solve it either since they'd be out of
| date and essentially one way if it took decades to get a
| response. No I think any interstellar colonization effort
| would immediately create competing civilizations distinct
| from their homeworld.
| jiggawatts wrote:
| Consider a colony of bacteria multiplying by splitting.
| Each new pair of cells is independent and do not
| cooperate. Some die, some stay put. Nonetheless, the
| "colony" spreads and explores new territory with zero
| coordination of these activities. Certainly not an
| intelligent centralised leadership!
|
| Even if our first interstellar colonies diverge
| immediately and some even turn into reclusive hermits,
| some may expand, repeating the cycle.
| FrustratedMonky wrote:
| I think the assumption is that 'transportation' between stars
| will be solved by sufficiently advanced aliens/us.
|
| BUT, that this will be one of those very difficult tasks, so
| it will take many thousands or millions of years.
|
| And so goes towards 'we are early'. So, if we are grabby, and
| all the other grabby aliens, are all still getting over this
| transportation hump.
| cwillu wrote:
| The universe isn't a rock concert, "we're here too early"
| is not the only possible reason why there's no band on the
| stage.
| FrustratedMonky wrote:
| ? Did you read the original post? On grabby aliens?
|
| This whole discussion is about being 'early'.
|
| Not sure you are making a point.
|
| Edit: The original post discusses below light speed
| transportation. 25% speed of light is used in the
| estimates.
|
| But guess I agree, if no aliens including us, never-ever
| with infinite time ever develop transportation that can
| get up to some fraction of light speed. Then maybe no
| colonization ever happens, and the grabby guys stay in
| their system.
| cwillu wrote:
| "Alas, there's a fifth possibility" was my comment, and I
| made it because the discussion was excluding the
| possibility, despite it being explicitly discussed in the
| paper.
|
| "We can't see any evidence because there is nothing there
| to see" is a possibility, grabby aliens _requires_
| significant-fraction-of-C travel for the argument to
| hold, and it's entirely possible that it's just
| impractical-to-the-point-of-impossibility. (That's why I
| quoted it in another comment).
|
| Yes, it's possible that we're early. It's equally
| possible that we're "early" because there's no concert:
| _everybody_ is early in a universe where the band never
| gets on stage and it turns out that nobody bothers
| colonizing the universe due to the cost and lack of
| benefits.
|
| See also: "Please don't comment on whether someone read
| an article. "Did you even read the article? It mentions
| that" can be shortened to "The article mentions that"."
| https://news.ycombinator.com/newsguidelines.html
| FrustratedMonky wrote:
| No. Your point is not clear at all.
|
| And I can ask for clarification concerning if you read
| the original post, since your objection/point was already
| covered.
|
| Did you read it and simply making some additional
| argument against it, or did you miss it entirely?
|
| "5. Controlled transportation between the stars,
| sufficient for colonization, is sufficiently impractical
| that there are no grabby aliens within our light-cone. "
|
| This is covered in the other points of the theory? So
| should I assume you read it?
|
| "The universe isn't a rock concert, "we're here too
| early" is not the only possible reason why there's no
| band on the stage. "
|
| "Don't be snarky. "
| https://news.ycombinator.com/newsguidelines.html
| yreg wrote:
| Even if interstellar travel is impractical, an advanced
| expansionist civ would be interested in building
| megastructures. And since there is no stealth in space
| (unless you can somehow mask heat), they should be
| observable.
|
| Ofc there are explanations for that part of the paradox as
| well, but the impractical travel theory doesn't cover it.
| zare_st wrote:
| A hypothetical megastructure Dyson's sphere would not
| radiate heat. And I'm not so sure that you can apply the
| stealth principle here. Stealth inhibits active measurement
| and astronomical measurements are passive. We have sensor
| resolution and we have a mass of data to sift through -
| each time sensor generation or data processing advances, we
| see stuff we haven't seen before.
|
| The data is analyzed as a dynamic system. Radar just looks
| at a bounce. If you setup radar incorrectly you might get
| false hits and no returns on valid targets. If you use a
| wrong model in analysis of astronomical data you're never
| getting anywhere close to a correct result.
| mattashii wrote:
| > A hypothetical megastructure Dyson's sphere would not
| radiate heat
|
| Could you elaborate why not? All current technology I
| know of has an efficiency of <100%, with waste energy
| being lost as heat (which in space would be radiated away
| in the infrared spectrum). Why would this not be the case
| for a hypothetical dyson sphere or swarm?
| zare_st wrote:
| Because the topic isn't about heat per se but heat
| signatures and detecting artificial heat signatures
| across the universe.
|
| Of course everything radiates heat I did not think I have
| to get down to that level in commenting here.
| yreg wrote:
| Sorry, I don't understand you either. Without new physics
| Dyson spheres radiate heat. Therefore they are
| detectable.
| cwillu wrote:
| A Dyson's sphere is a device to convert high frequency
| photons (visible light and uv) to low frequency photons
| (radiated "heat"). A sufficiently deep stack of shells
| can bring the temperature of the radiated light closer to
| the temperature of the cosmic background radiation, but
| it absolutely will radiate.
| zare_st wrote:
| Which is exactly my point.
|
| The question isn't whether Dyson speheres radiate, the
| question is can we detect an artificial megastructure and
| my answer is no, based on the hypothetical Dyson design.
| cgriswald wrote:
| That is physically impossible unless there is new physics
| in that hypothetical design. All physical objects radiate
| heat and a Dyson sphere in particular would be trivial to
| detect. You look take a picture of the sky in infrared
| and in the visible spectrum. If you find an infrared
| source but no associated visible star you've got a strong
| candidate for being a Dyson sphere. Such searches have
| actually been conducted.
|
| Other megastructures might be discovered through the same
| methods as exoplanets.
| shrimp_emoji wrote:
| You're implying we'd easily see megastructures. Believe it
| or not, there's many more stars we haven't inspected than
| have. And our telescopes suck too much to see all but the
| largest megastructures, which you're assuming it would make
| rational sense to build in the first place. There can be
| better things for an economy to spend its (always finite)
| resources on.
| yreg wrote:
| > which you're assuming it would make rational sense to
| build
|
| Yes I mean why not. If you are an expansionist advanced
| civ, travel is impractical and you have enought time and
| resources then what else is there to do?
|
| Obviously there are explanations "why not" (as I said),
| but insterstellar travel unavailability is not one of
| them.
| scotty79 wrote:
| Lightsail seems sufficiently practical if you don't care
| about being fast. You basically directly exploit energy of
| the stars you are traveling between.
| cwillu wrote:
| The argument is premised on grabby aliens being fast enough
| to explain why we don't see their expansion; grabby aliens
| that don't care about being fast would have showed up
| _long_ ago.
| api wrote:
| There are many middle possibilities between that and aliens
| expanding at c.
|
| Expansion at c is very unlikely. Insane things happen when
| you approach c, like the cosmic microwave background
| transforming into a gamma ray laser aimed at your head and
| collisions with microscopic particles destroying you. It may
| be that travel close to c is so hard as to be effectively
| impossible.
|
| I've read that speeds up to about 30% the speed of light are
| "thinkable" with currently known physics plus advances like
| compact fusion reactors. Think something that looks like the
| Epstein Drive in The Expanse or the ships from Avatar.
|
| These models provide indirect evidence against the existence
| of FTL travel. If FTL exists it means we really have to be
| _extremely_ early, maybe even the first in our galactic
| cluster. Otherwise someone would have visited at least.
|
| I also think if someone has visited, such as if some tiny
| number of UFOs are actually of ET origin, it means we are
| probably incredibly lucky to have neighbors that aren't
| "reapers" in the dark forest sense. It'd be funny if our
| galaxy is actually full of aliens and we lucked out and are
| camped next to some superintelligence that is both benevolent
| and powerful enough to fight off anyone who isn't. So hey if
| they're taking our cattle maybe that's a pretty small price
| to pay.
| brazzy wrote:
| My money is on option 2 with the key factor being that complex,
| intelligent life takes a _long_ time to develop. Our empirical
| data (of sample size one) indicates that it takes multiple
| billions of years to go from single celled life to even quite
| simple multi-celled life. If we got lucky with that, the
| average could easily be longer than the age of the universe.
| willis936 wrote:
| The problem with option 3 is that even a small drop below light
| speed becomes a large multiplier when looking at galactic and
| intergalactic distances. Let's say you can manage 0.5 c
| (pushing far beyond any current physical understanding of what
| is possible), that means we would have up to a 40,000 year
| heads up on an approaching galactic civilization. Even if it
| was 0.9c we would have up to 8,000 years notice. Even with
| something crazy like direct antimatter - matter conversion the
| amount of energy to bring a ship to that kind of speed would be
| a gigantic beacon in the night sky. Barring science fiction we
| can be relatively confident none are on their way right now.
| pfdietz wrote:
| Given that the universe is 13.8 billion years old, 40,000
| years is nothing.
|
| The presumption that other putative galactic civilizations
| start at nearly exactly the same time as us is implausible,
| especially considering more than 9 billion years passed
| before the solar system even formed.
| willis936 wrote:
| Sure, but we'd see the markers on timescales relevant to
| us. The gap between the light cone and actual velocity is
| the critical difference between a kugelblitz and an
| invasion: you could conceivably conceal the former but not
| the latter.
| pfdietz wrote:
| I'm pointing out that any scenario that requires this
| synchronization is inherently implausible. So if we don't
| see the markers, trying to say it's because there are
| lots of civilizations but they just happened to pop up in
| synchrony with us is not a plausible theory.
| iraqmtpizza wrote:
| All evidence says that humans stand alone in the galaxy.
|
| Everything else is cope.
| LadyCailin wrote:
| That's like looking only in the drawer, and saying, there is
| no evidence here that a cat lives in this house. When in fact
| the cat is just upstairs.
| iraqmtpizza wrote:
| There are electromagnetic waves reaching the earth from
| this galaxy which were emitted anywhere from 80,000 years
| ago to an instant ago, and everywhen in between.
| Practically all alien races among the hundreds of billions
| of solar systems would have to have been
| electromagnetically silent for a minimum of 80 thousand
| years for us not to see them.
|
| If you include other galaxies, then they would've had to
| have been silent since the beginning of time.
|
| Also, non-living matter spontaneously forms into living
| matter by no known mechanism.
|
| If you're going to believe something religiously, make it
| something less trivial than muh aliens.
| throwuwu wrote:
| Not silent, just not broadcasting.
| iraqmtpizza wrote:
| Okay, so you imagine a galaxy-wide communist society in
| which everyone is successfully prevented from emitting
| any unencrypted signal from so much as a Dyson
| refrigerator, for tens of thousands of years at a time.
| throwuwu wrote:
| No, I imagine them doing exactly the same thing we are:
| using more and more efficient methods of communication as
| we develop them. Compressing and encoding data, focusing
| our transmissions where they need to be instead of
| blasting at max power in all directions, using the most
| effective form of transmission for the purpose whether
| it's laser, microwaves, specific wavelengths of radio, or
| hard line connections for planet side comms. Signals
| decay very rapidly over distance so unless you have a
| very good reason to build a gigantic transmitter capable
| of reaching beyond a few light years in all directions
| you're not going to just accidentally wind up
| communicating with a random star 100ly away.
| iraqmtpizza wrote:
| Oh, yeah, because zero of the roughly 5 quintillion
| aliens which the Milky Way could comfortably support have
| hobbies (very primitive) and none would ever use a cheap
| and effective terraforming unit or dyson sphere even once
| in 80 thousand years when they could use a more expensive
| one which mimics pure blackbody radiation
|
| even in war (or are they pacifist communists), they would
| never emit a signal for any reason on any of the multiple
| trillions of planets during this 80,000 year period. not
| even from a bomb.
|
| yes, yes; this all makes sense -- I have done the math.
|
| maybe all 5 quintillion aliens are being hunted by
| equally non-emitting terminators and they don't want to
| give themselves away and also they want to save energy
|
| directional communication makes sense when you have only
| two planets. if you have an entire solar system (or the
| entire galaxy) it's a dumb idea to eschew simple
| omnidirectional devices
| jiggawatts wrote:
| Just not broadcasting powerfully enough to be detected by
| our current technology... which can only detect very
| powerful broadcasts very close to us.
| beAbU wrote:
| You might enjoy this creepypasta of yore...
|
| https://creepypasta.fandom.com/wiki/Radio_Silence
| not_the_fda wrote:
| I don't think we are alone. We are just separated by enormous
| amount of distance, and inter-solar system travel isn't
| feasible.
| gmuslera wrote:
| It feels like talking about religion. In a lot of them at the
| very least, there is an almighty, omniscient god, the alpha, the
| everyday, and the omega god, the one that maximizes knowledge,
| intelligence, power, whatever. And people following that religion
| know exactly how that entity thinks and behave. Because that
| entity should think like humans of the current culture does, no?
|
| With aliens, with a different culture, civilization if that
| concept applies, language or not, and enough technology to make
| interstellar travel, and all of that for thousands to millions of
| years, those aliens that are far beyond our imagination, well,
| somewhat we know how they think and should behave, now knowing
| the technology they should have, the knowledge about the universe
| they should have, philosophy or whatever.
|
| We don't even know if it will be ever practical interstellar
| travel, because we didn't reach that stage yet. In theory it
| should work... in theory I could climb stairs till reaching the
| moon too. People is too busy trying to figure out how advanced
| aliens should think, and didn't stopped to analyze how they are
| thinking.
| kiba wrote:
| _We don 't even know if it will be ever practical interstellar
| travel, because we didn't reach that stage yet. In theory it
| should work... in theory I could climb stairs till reaching the
| moon too. People is too busy trying to figure out how advanced
| aliens should think, and didn't stopped to analyze how they are
| thinking_
|
| By using our knowledge of physics, we can make reasonable
| speculation on what is possible and not possible, and what
| engineering we need to do to make these effort successful. Some
| people's work are so successful that they became foundational
| to our knowledge base today.
|
| Same as with aliens. We can make reasonable extrapolation on
| what we might see from the type of aliens that expand versus
| and aliens that don't. They are of course, guesses, and those
| guesses continued to be argued and refined. Note that the site
| doesn't assumed that all aliens are grabby, only that some are
| grabby aliens, and try to extrapolate on what it might look
| like if they are grabby.
| pavel_lishin wrote:
| > _By using our knowledge of physics, we can make reasonable
| speculation on what is possible and not possible, and what
| engineering we need to do to make these effort successful_
|
| Our speculation is only as good as our understanding of
| physics. Which is pretty good! But people in 1800s thought
| they had discovered just about everything to be discovered,
| and thought themselves at the end of physics, too.
| kiba wrote:
| Eh, people like to extrapolate by analogies. Doesn't
| actually mean that it's true.
|
| We can only reasonably speculate using our existing
| knowledge base. Doesn't mean that people literally think we
| know all there is to physics. People even acknowledged that
| it's incomplete.
| o11c wrote:
| > And people following that religion know exactly how that
| entity thinks and behave. Because that entity should think like
| humans of the current culture does, no?
|
| Those are really interesting claims you make. Very often I see
| the exact opposite claims out there: humans have almost no idea
| what the god(s) are really thinking, and religion seeks to
| _contrast_ itself from the surrounding culture.
|
| (that's not the biggest philosophical conflict I see in
| religious discussion, but the other is Christian-specific)
| pavel_lishin wrote:
| > _that early deadline explains human earliness._
|
| I don't buy these statistical arguments.
|
| If only one sentient species is born before 20 billion years have
| passed since the big bang, and ten million sentient species are
| born after that time, yes - statistically, you're more likely to
| be one of the later species.
|
| _But that early worm species still exists, and experiences its
| existence._
|
| If they thought to themselves, "obviously there's others out
| there, it's statistically certain!", then they are _wrong_.
| behringer wrote:
| 20 billion is a long time, and the universe is very big. And
| we're not the first galaxy to form within that 20 billion year
| time frame.
|
| It's very likely we're not the first in the universe and it's
| also likely we're not alone in coming to sentience at this very
| moment in the universes life.
| MrScruff wrote:
| What I don't understand is how we reasonably quantify the
| probability of sentient life evolving. Sure the universe is
| very big, but the probability could be very small. All the
| discussions I've seen make the assumption that there's
| nothing unusual about life on Earth and given similar
| conditions elsewhere we would expect to see life, but how
| does one conclude that from a sample size of 1?
| qnleigh wrote:
| I guess the argument is something like 'if life is unlikely
| to evolve, then it is surprising to find ourselves existing
| so early in the history of the universe. If life is likely
| to evolve, then how do we explain being apparently alone?'
| and then the grabby aliens theory tries to answer the
| second question.
|
| I don't find the argument convincing though (per my other
| comment)
| pfdietz wrote:
| But we are not "so early" in the history of the universe.
| Something like 95% of all the stars that will ever be
| formed have already been formed. It's actually rather
| late in the day.
| qnleigh wrote:
| I agree. I didn't know that statistic, but that was my
| impression from other things I've heard.
| eightysixfour wrote:
| > While the current date is 13.8 billion years after the Big
| Bang, the average star will last over _five trillion years._
|
| That does not seem right. Isn't the lifespan of a star between
| 100m and 100b years or so?
| eschaton wrote:
| I think it depends on what you mean by "last," a star might
| "last" even longer than 5x10^12 years before the last component
| nucleons of its remnant evaporate. If you consider how long a
| star lasts to be how long it emits around the same amount of
| energy until becoming another class of object the time will be
| shorter.
|
| Sol will grow large and red in another 4x10^9 years or so, then
| after that phase it'll leave a stellar remnant like a brown
| dwarf or neutron star, which will last another period of time.
| How long did Sol last?
| brazzy wrote:
| No, it doesn't depend on any such interpretation. The key
| word is "average". A majority of stars are red dwarves, and
| those do in fact last for trillions of years without
| significant change.
| dang wrote:
| Related:
|
| _Grabby Aliens: A Resolution to the Fermi Paradox_ -
| https://news.ycombinator.com/item?id=33402628 - Oct 2022 (334
| comments)
|
| _Grabby Aliens_ - https://news.ycombinator.com/item?id=26502232
| - March 2021 (176 comments)
|
| _A Simple Model of Grabby Aliens_ -
| https://news.ycombinator.com/item?id=26045731 - Feb 2021 (80
| comments)
| ck2 wrote:
| the fantastic PBS Space Time on the subject
|
| https://www.youtube.com/watch?v=uTrFAY3LUNw
| mapmeld wrote:
| My go-to counterargument for this is that galaxies are really far
| apart (from us to Andromeda is 25x the diameter of the Milky
| Way). If you haven't developed FTL travel, it's a long haul with
| very little benefit on the way.
| a_wild_dandan wrote:
| Your "counterargument" is a presumption in Fermi paradox
| models. The alternative isn't particular interesting.
| Animats wrote:
| Actual article: [1]
|
| _" We estimate that loud alien civilizations now control 40%-50%
| of universe volume, each will later control ~ 10^5 to 3 x 10^7
| galaxies, and we could meet them in ~200 Myr-2 Gyr."_ Those
| numbers seem inconsistent.
|
| _" Ours is a model of grabby aliens, who by definition (a)
| expand the volumes they control at a common speed, (b) clearly
| change the look of their volumes (relative to uncontrolled
| volumes), (c) are born according to a power law in time except
| not within other GC volumes, and (d) do not die unless displaced
| by other GCs."_
|
| That's an interesting set of assumptions. Kind of a 1960s science
| fiction model.
|
| If we now have a reasonable understanding of physics, you get a
| different model. No FTL, radio works at light speed,
|
| Technological civilizations may not last all that long. Human
| civilization is about 6,000 years old. Heavy industrial
| civilization is about 200 years old. Most mineral resources
| already are past the point where the easy stuff has been mined.
| The USGS tracks total worldwide mineral resources.[2] On a scale
| of years, things look good. On a scale of centuries, not good. On
| a scale of millennia...
|
| [1]
| https://iopscience.iop.org/article/10.3847/1538-4357/ac2369/...
|
| [2] https://www.usgs.gov/publications/mineral-commodity-
| summarie...
| cryptonector wrote:
| The speed of light is a tremendous limitation. W/o FTL there's
| no such thing as "loud alien civilizations" that can "control
| 40%-50% of [the] universe['s] volume".
| XorNot wrote:
| Rather depends on other factors though: you can perfectly
| well run an interstellar empire with very long communication
| times and people going into suspended animation for transit.
|
| Control strategy simply has to adapt accordingly: i.e. a
| message probably comes with a fleet sufficient to ensure its
| obeyed.
|
| This was one of the ideas in the Doom novelizations: that the
| aliens had spent so long travelling that there was little
| chance of victory because of you attacked a place you took
| along everything needed for overwhelming victory.
| Mistletoe wrote:
| Suspended animation may be as impossible as faster than
| light travel.
| pfdietz wrote:
| Much more plausible, IMO.
| ben_w wrote:
| We've already got examples of small creatures in
| suspended animation.
|
| I only wish Alcubierre-type drives were as well-developed
| as that.
| Animats wrote:
| > Rather depends on other factors though: you can perfectly
| well run an interstellar empire with very long
| communication times and people going into suspended
| animation for transit.
|
| Probably not. Historically, a few months of lag is roughly
| the upper limit for running an empire. The Roman empire got
| round trip lag down to two months to the distant provinces.
| The Spanish empire was at 4-5 months of lag for the New
| World. Holding an empire together with a lag of decades
| probably won' work.
| cryptonector wrote:
| > you can perfectly well run an interstellar empire with
| very long communication times and people going into
| suspended animation for transit.
|
| If travel times are orders of magnitude longer than
| lifetimes, then you will tend to lose civilizational
| cohesion.
|
| > Control strategy simply has to adapt accordingly: i.e. a
| message probably comes with a fleet sufficient to ensure
| its obeyed.
|
| What even is the point? The message takes N years to be
| received by a receiver N light-years away, but travel times
| will be orders of magnitude longer, so no "fleet" can be
| sent.
| exe34 wrote:
| The fleet carries the message.
|
| Of course, there's a fair chance that by the time the
| fleet gets there, the colony is long dead, or has
| advanced in weaponry in a different but overwhelming
| direction, so they just barely notice the little flash
| way out past their oort cloud.
| XorNot wrote:
| Ascribing limited-lifespan human motivations to
| potentially infinite lifespan non-human intelligence is
| the core mistake here though.
|
| You look at running an empire with hundreds of years of
| message delay as pointless, they may view it as totally
| necessary. After all - if from your subjective opinion
| you blink and you're in another star system (hundreds of
| years later), then are you even worried about that time
| difference, or are you worried about whether they're
| still flying the right flags when you get there?
|
| (you can imagine a similar arrangement of times working
| out for social relationships over such timespans -
| duration might not much matter if everyone sort of agrees
| they'll wake up for X amount of subjective time before
| meeting up again in person).
| FrustratedMonky wrote:
| AI.
|
| Instead of FTL, or FTL communication lines, or forms of
| suspended animation.
|
| The ships that are sent out could be run by an AI. Maybe
| the ships are factory ships to self-replicate.
|
| The Grabby could be more like Blindsight.
| cwillu wrote:
| As stated in the paper: "The second of our three model
| parameters is the (assumed universal) speed at which grabby
| civilizations expand. Our model predicts that on average at
| grabby origin dates, a third to a half of the universe is
| within grabby-controlled volumes. So if the grabby expansion
| speed were low, many such volumes should appear quite large
| and noticeable in our sky. However, as noted by (Olson '15;
| Olsen '17) and discussed in Section 13, if their expansion
| speed were within ~25% of lightspeed, a selection effect
| implies that we are less likely to see than to not see such
| volumes. Thus if we could have seen them, they would likely
| be here now instead of us. As we do not now see such volumes,
| we conclude that grabby aliens, if they exist, expand very
| fast."
| cryptonector wrote:
| They couldn't be cohesive civilizations though, not unless
| their individual lifetimes were _very_ long.
| ben_w wrote:
| While true, a poor choice of name doesn't invalidate the
| logic.
|
| I'd call them "lineages" for this reason, but I don't
| really expect the name to catch on.
| scotty79 wrote:
| We are living an mining just the skin of our planet. If we
| achieve technologies to extract interesting resources out of
| magma w could have boundless resources.
| brazzy wrote:
| This kind of thing always has the same weakness: it's
| extrapolating from a sample size of one. It of course tries to
| account for that by adding large error margins based on what we
| know, but for some of them it's pure guesswork that could easily
| wrong.
| qnleigh wrote:
| I'm confused by the argument here; is the argument that 'humanity
| could not arise once the universe has been taken over by grabby
| aliens, so a possible explanation of finding ourselves existing
| so early in the history of the universe is that this will be the
| only opportunity'?
|
| But if the universe will soon be filled with gajillions of grabby
| aliens, who's to say that we couldn't have been born as grabby
| aliens instead of humans? In fact if there will be so many of
| them, isn't the fact that we're not grabby aliens ourselves
| evidence that there will be no grabby aliens?
|
| I feel like there is some implicit assumption about 'who you are
| likely to be born as' that I'm not getting here. Do I need to
| assume that I could only have been born as a human for the
| argument to go through?
| ben_w wrote:
| It's saying there's a good chance we'll be one of the grabby
| civilisations.
|
| Or at least, it doesn't rule it out. Non-grabby aliens aren't
| visible in this model; given the distances, "grabby" is the
| only way to change the environment enough for current human
| tech to even notice something unusual.
| qnleigh wrote:
| But if we'll become a grabby civilization, then there will
| presumably be at least trillions of humans born in the
| distant future who will live all throughout the universe.
| Isn't it that an extraordinary coincidence to find oneself
| born among the first few billion?
|
| Incidentally, Carl Sagan used the above line of reasoning as
| a sign that human civilization was going to collapse before a
| few more doubling times.
| Towaway69 wrote:
| My thinking is that the universe is full with life and
| communicating life. However communication is only possible with
| the right technology.
|
| What is that technology? Technology that can only be created by a
| harmonious society working together to share ideas and combine
| ideas from everyone in a non competitive manner.
|
| In that way the universe ensures peace and harmony ensures
| knowing that warring civilisation aren't able to leave their home
| base nor communicate with the universe.
|
| It might sound slightly esoteric and spiritual but there many
| ways to societally live together in harmony with all humans.
|
| After all not one individual can completely understand the
| universe, how can one nation hope to reach out to a non
| understandable universe.
| 8jef wrote:
| The idea of global harmonious cooperation represent the main
| evolutionary threshold appearing before us all. This should be
| our future, if We all individually find enough trust in
| ourselves, and let us collectively evolve in such direction.
|
| And as We, I do not foresee only human beings, but more broadly
| the Living, as We, interspecies from Earth. Finding a way to
| unite individualities should include ways to establish
| communication channels with so-called wildlife individuals.
|
| The idea of considering such a path being esoteric is a way to
| get distrustful people on board, which may be a waste of time
| and resources. We should focus on uniting everyone who already
| think this is the new normal.
| Towaway69 wrote:
| Well said and thank you for saying it.
|
| And yes, we should start at home and begin communicating with
| our surroundings. Be it the planet or the species with whom
| we share this spaceship earth.
| yreg wrote:
| How can a particular technology have a non-competitive
| harmonious society as a hard requirement for it's discovery?
| Towaway69 wrote:
| Think of technology that we can't imagine.
|
| Just as we can't imagine a harmonious society, so we can't
| imagine the technology that would arise from such a society.
|
| It's a recursive argument, I know, but that's the core of the
| problem.
| yreg wrote:
| I'm sorry, but this seems like handwaving. I don't see why
| we couldn't imagine the technology?
|
| Perhaps we are using technology in different context. I
| mean understanding of physics + a machine (made out of
| matter) built thanks to that understanding. Do you perhaps
| mean something else?
| Towaway69 wrote:
| Not wanting to handwave, I was suggesting that I don't
| know what this technology might be.
|
| Sure we can have ideas and possible approaches but just
| as many scifi authors thought that we would be flying
| around instead of driving by now, it doesn't have to be
| the right idea.
|
| My favourite idea is to consider the planet our spaceship
| and ensuring our existence into the future the technology
| that we need. It does seem to be the hardest problem to
| solve currently.
| api wrote:
| Not a tech per se but I think they'd be more efficient.
| They'd go for standardization as the default, which would
| mean far less duplication of effort. They'd only break with
| that if a gain was to be realized.
|
| In many cases higher rank humans block innovation because it
| threatens them. There'd probably be less if that too.
| Personally I suspect this is one reason it took 300000 years
| for humans to start building significant technology.
|
| The thing that's hard to imagine is what the driving force
| would be without much conflict. Conflict and competitions are
| easy motivators, at least for us. But a being with a
| different psychology might have different drives. It doesn't
| have to be conflict that motivated growth, just some drive
| that ties into motivation.
| Towaway69 wrote:
| I think if we look at pure science (science outside of
| publish-or-die commercial universities) and see the desire
| to learn and discover, that is plenty of motivation for
| many.
|
| Humans have a natural urge to be inquisitive and make their
| life's simpler. Obviously if war and conflict were to be
| the only motivational possibilities, then I do wonder how
| we made it down from the trees!
| qnleigh wrote:
| If the resources required to communicate are planet-scale,
| then it would require comparable cooperation to build it.
| Maybe that gets you somewhere. And then maybe you choose to
| communicate in a way that requires massive resources at the
| receiver end too... Not a full answer to your question, but
| this gets you somewhere.
|
| A more compelling answer to me is this; civilizations that
| don't learn how to cooperate at the scale of their planet
| will destroy or deplete it before they are able to build
| something of this scale. We have some evidence for this
| suggestion here on Earth...
| yreg wrote:
| Planet scale cooperation utilizing planet scale resources
| is possible in a planet scale military dictatorship as
| well. Actually it sounds easier and more plausible than in
| a free society.
|
| > A more compelling answer to me
|
| Agreed, but that's just the usual great filter idea.
| Towaway69 wrote:
| > Actually it sounds easier and more plausible than in a
| free society.
|
| It doesn't have to be but with our current mindset, I
| would agree.
|
| If imagining a cooperative society is hard then it is
| even harder to imagine the technology that would arise
| out of such a society.
|
| Edit: for me the open source software movement is a good
| example of what a cooperative society could do. In 40
| years we have gone from room size computers to mobile
| device that can communicate with anyone on the planet and
| have access to all the worlds knowledge. This would never
| have been possible IMO without millions of developers
| sharing their knowledge.
| not_the_fda wrote:
| I think there is a great filter. The trait that makes a species
| grabby is also the trait that leads to its downfall. They end up
| destroying their home ecosystem before they can achieve inter-
| solarsystem travel, wiping themselves out.
| bonzaidrinkingb wrote:
| This theory is itself grabby, and grabs itself at that.
|
| > Furthermore, we should believe that loud aliens exist, as
| that's our most robust explanation for why humans have appeared
| so early in the history of the universe. But if loud aliens will
| soon fill the universe, and prevent new advanced life from
| appearing, that early deadline explains human earliness.
|
| Even furthermore, we should believe that Big Foot Medusas exist,
| as that's our most robust explanation for why humans have not
| seen these yet and are still alive. Since Big Foot Medusas turn
| everything alive into stone upon observation, and we are still
| here, it suggests we are early in our explorations and
| observations of Big Foot Medusas.
|
| Anyway, a loud grabby alien civilization expanding is "first
| come, first serve". Perhaps we have not seen grabby aliens,
| because the first grabby aliens became quiet, and make new grabby
| aliens impossible, or they finally became superrational and
| realized they need more than one civilizations to have an
| economy, cooperation, cosmodiversity, or competition: If aim is
| to win at tennis, you can't play tennis alone.
|
| As for earth specifically, it was probably already grabbed, and
| humans are the terraforming organisms put in service of the
| grabbies to make our planet habitable. Or the grabbies are in
| such a zeal to expand and get the most of our galaxy that they
| focus on planets that are close to the horizon, after which they
| will be moving away at faster than light speeds due to
| accelerating expansion of the universe. Only after that will they
| get around to Earth (first building a Dyson Sphere around the
| universe to harness its energy).
| BugsJustFindMe wrote:
| Yeah, the first reaction to "we should believe that loud aliens
| exist, as that's our most robust explanation for why humans
| have appeared so early" should be "sorry, but that's not how
| explanation, loudness, or existing work."
|
| The most robust explanation for why we're here now is that
| unlikely things happen all the time, and we only think that's
| weird because of anthropic bias.
| johnfn wrote:
| If you yourself are a Big Foot Medusa then I would believe this
| logic.
| makeworld wrote:
| > humans are the terraforming organisms put in service of the
| grabbies to make our planet habitable
|
| Now there's a thought.
| geon wrote:
| Or we are the descendants of a failed colony.
| antifa wrote:
| It is interesting, but I think a civilization capable of
| planning on million year timescales would have a better plan.
| Veserv wrote:
| Of course it makes no sense if you are answering the wrong
| question.
|
| The question being asked is not: "Why do we not see grabby
| aliens?"
|
| The question being asked is: "Under what circumstances can
| humanity become grabby aliens that colonize the galaxy in
| reasonable time given that we do not see grabby aliens?"
|
| The simplest circumstances that would allow humanity to become
| grabby aliens in the future is that becoming grabby aliens is
| easy for a modern human-like society. However, grabby aliens
| that colonize the universe in reasonable time preclude humanity
| from existing if we intersect with their existence.
|
| That means there must either be something else special about
| our existence, or that we are unlikely to ever become grabby
| aliens. That is the entire point of the thought exercise,
| figuring out if there is a hope that humanity will become
| grabby aliens (Star Trek).
| gcanyon wrote:
| In case anyone is interested in how grabby aliens (or we!) could
| travel the galaxy, Kurzgesagt has an excellent video on building
| a stellar engine to move our solar system at up to 50 light years
| per million years. Setting aside considerations of whether we'll
| survive the next few decades as a technological civilization, let
| alone the next few millions of years, the Caplan engine would let
| us colonize a significant fraction of the galaxy within a billion
| years or so.
|
| https://www.youtube.com/watch?v=v3y8AIEX_dU
| jojohohanon wrote:
| Why are we now?
|
| https://www.ox.ac.uk/news/science-blog/why-are-we-now
|
| It's early here, but it think the gist of it is using Bayes to
| quantify:
|
| Given that the universe would seem to get more hospitable at
| older ages,
|
| why are we alive now?
|
| IIUC the most likely explanation is some secondary force (
| _aliens_ ) to modify the future hospitality.
| flenserboy wrote:
| Ecosystems on Earth might be a better way of thinking about this.
| Notice how we do not see one organism or type of organism squeeze
| out all the others, or work to take in all energy available to
| them; this is also true of human settlements, whether rural or
| urban. There is a clear diversity of energy extraction methods, &
| singular dominance (think algae-clogged lakes) tends to lead to
| stagnation & death. Mechanical expansion might look grabby (as in
| Von Neumann probes), but life expanding through the universe
| could instead follow biological & human-settlement patterns.
___________________________________________________________________
(page generated 2024-02-11 23:01 UTC)