[HN Gopher] If Loud Aliens Explain Human Earliness, Quiet Aliens...
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If Loud Aliens Explain Human Earliness, Quiet Aliens Are Also Rare
Author : Borrible
Score : 75 points
Date : 2021-09-22 09:56 UTC (13 hours ago)
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| candiodari wrote:
| If you look at the realistic reach of the signals of human
| civilization, it's a few tens of lightyears at best.
|
| And once you factor in how inhumane it'd be to send children out
| to colonize foreign solar systems ... are we really sure we'll do
| that? That's 10 generations that live their entire lives in small
| metal boxes ... without the vast majority of everything we have
| on earth. Not so much as a single field of grass (or field of
| anything, building a big room in space will be a great challenge,
| especially since weightlessness means you don't really need
| room).
|
| 10 generations that will have absolutely zero power to do
| anything about their situation. It will take 100+ generations
| before anything remotely resembling earth level comfort will
| happen (assuming the planets encountered can at any point support
| human life. If they need to be terraformed, we're easily talking
| 1000+ generations)
| dogma1138 wrote:
| That's an accurate statement the reality is that any
| civilization that develops sufficient level of technology to
| allow it to spread across a single galaxy or even to adjacent
| star systems would be able to use that technology to find
| better alternatives in their own star system.
|
| That's if civilizations even live that long in the first place.
| Ekaros wrote:
| Minimal fraction of suns energy output would allow insane
| number of humans to survive. And it will be around a while so
| there is really no hurry to move out.
|
| Kinda comes to calculation that when earliest potentially
| space faring civilisation runs out of their sun? And can't
| adapt to live in system. For us that would still be at least
| few billions of years if not more with proper preparation.
| Nbox9 wrote:
| I could imagine humans fighting over the limited energy
| harvested by Sol's Dyson sphere in 10million years. It
| would give any group of human's controlling it a massive
| advantage, similarly to the advantage having the only
| A-bomb gave US briefly.
| SubiculumCode wrote:
| Maybe. Just maybe. We will have artificial fusion energy
| in 10M years. ;)
| giantrobot wrote:
| There is an absolutely stupid amount of energy given off
| by the Sun. We're finally waking up to the fact we can
| capture a portion of the small portion that hits Earth
| every second to power our civilization.
|
| Higher technology levels have only increased the
| efficiency of our power use and use per capita. I'm not
| saying we're at the height of technology or development
| or anything but the idea we'd need a whole star's worth
| of power output for _something_ I think is ludicrous.
|
| If you've got the technology to build a Dyson sphere (or
| swarm) it's unlikely you'd actually need to. To even get
| to that point as a tool-using civilization you couldn't
| have had unchecked geometric growth. Unless you had some
| Motie-like biological imperative to reproduce
| uncontrollably your civilization would reach a point long
| before Dyson sphere level where it worked fine without
| having to move the mass of several solar systems around a
| star to capture some high fraction of its power output.
| rsynnott wrote:
| That's assuming that people have an inexhaustible
| appetite for energy, geometric population expansion, or
| both. Those are both actually quite big assumptions and
| aren't supported by current trends.
| Ekaros wrote:
| On the other end, looking at the population growth
| projections there might not be too many humans to fight
| over it in 10 million years.
|
| Who am I kidding, they would still fight over it...
| Nbox9 wrote:
| I'm unsure the human rights aspect is going to be the limiting
| factor. Humans are constantly doing inhuman things. We have a
| history of forcibly migrating people, it's not uncommon in our
| history at all.
|
| I think it's just as likely that we never spend the engineering
| effort on a multi-generation colonization ship. Compared to
| inner-stellar travel inter-stellar travel requires much much
| more space, robust systems, and reliability. For example, the
| distance between Earth and the nearest star is over 100,000,000
| times the distance between Earth and Jupiter. It's questionable
| we'll ever put the effort into being inner-stellar, but the
| difference between inner-stellar and inter-stellar is greater
| than the difference between a paddle board and an aircraft
| carrier.
| ido wrote:
| Assume we survive climate change as a technologically
| advanced society & that no other natural disaster or war wipe
| us out, so you really think you can predict what sort of
| technology will or will not be available to humans 1,000
| years from now? How about 1,000,000?
|
| If in those time spans we figure out a way to sustain 1g
| acceleration throughout the trip (currently not achievable
| but less sci-fi than FTL) we can reach nearby stars within
| the lifetime of the astronauts: https://www.forbes.com/sites/
| startswithabang/2021/12/30/how-...
| kypro wrote:
| But why would a sufficiently advanced civilisation choose to
| colonise the galaxy with organic human-like beings? Surely it
| would make far more sense for this hypothetical civilisation to
| send robots first? A technologically advanced civilisation is
| also likely to rebuild their organic bodies specifically to
| overcome these limitations, in which case concerns around
| terraforming really aren't that big a deal.
|
| The problems you're raising are far more technological in
| nature than fundamental IMO. I agree that as it stands it
| wouldn't make much sense to attempt to colonise the galaxy even
| if we had the rocket technology today, but by the end of the
| century we'll probably have the kind of technology required to
| colonise the galaxy (robots, AI, improved battery tech) even if
| we're still stuck with slow combustion rockets.
| nexuist wrote:
| This adds a new, unexpected element to the alien visitation
| theory: the aliens that come here will not be alive at all,
| they will be robots programmed to extract resources that
| cannot be reasoned with diplomatically (assuming they are not
| outfitted with general intelligence). Unless the senders
| thought ahead and built empathy into the robots, there will
| be no way to end the invasion other than to kill everything
| that comes here.
| baja_blast wrote:
| There are no resources on Earth that a space fairing
| civilization or robot would need that they couldn't get far
| more practically from asteroids. Earth is a gravity well,
| extracting resources from the planet and getting it off is
| way harder than just mining Kuiper belt, lots of water,
| minerals, metals anything they would need.
| bluGill wrote:
| One exception to that: gravity. The only reason I can
| think of they would want our gravity is if they want to
| live here though, so we are back to them not sending
| robots which we already agreed isn't likely.
| jjk166 wrote:
| Even our oldest running computers are young by human
| standards, and downright primitive compared to what we are
| producing today. Machines are not immortal, at best they are
| easier to repair than lifeforms but that's not of much use if
| there's no one to repair them. The voyager probes are in
| their 40s, and it's not looking like they're going to make it
| into their 80s. While we can certainly build more robust
| machines with more redundant components, the fact is without
| FTL the overwhelming majority of a galaxy is tens of
| thousands of years away at a minimum[0]. Building things to
| last over such timeframes in a harsh environment like space
| may not even be possible, nonetheless practically achievable.
|
| Even if one assumes we can make such long lived machines, the
| question becomes why? By the time such a craft reaches its
| destination, every being that worked on its construction, and
| all of their descendants for many generations, and indeed
| possibly the civilization itself, will be gone. Even if some
| institution still remains, it will be too far away to
| communicate with, nonetheless transfer anything with mass.
| Whether operated by cloned beings or AI, this new settlement
| is in no way a part of the originating civilization, at least
| not any more than some ancient Egyptians shipped off 1000
| lightyears away would nowadays be a part of ours. There may
| be legitimate reasons to set up a few colonies, such as
| backups in case of solar-system scale catastrophes, but by
| the time you've expanded out even just 100 lightyears
| (0.0001% of the galaxy), there are already tens of thousands
| of systems in your "empire". Of course civilizations don't
| need to act rationally all the time, even though they might
| derive no benefit they might do something just because they
| can. But how many times are they going to do this just
| because they can? 10 times, 100 times? 10,000 times?
| Eventually the novelty is going to wear off, and those
| massive quantities of resources being spent on these
| extremely expensive spacecraft are going to be repurposed for
| the betterment of the civilization.
|
| Now let's say that, despite the extreme technical challenge
| of travelling more than a few tens of lightyears, and despite
| the complete lack of rational reason to do so, a civilization
| decides to just keep expanding anyways. Eventually they are
| going to encounter another civilization. This continuous
| growth is a threat to any other civilization - even if they
| agree to leave their neighbors alone, they are still
| ravenously consuming the resources in the area that such a
| civilization would want to have access to in the future. It
| is in their best interests to get the expansionist
| civilization to stop - possibly by diplomacy, possibly by
| other means. The expansionist civilization is squandering
| resources on its expansion, it's likely a young civilization
| that only recently developed the means to expand, its
| periphery is thousands of years less advanced than its core
| region and likely very underdeveloped, it has no means to
| move its assets to the periphery or concentrate its forces in
| the short term, and it has extremely long supply chains in
| the long run. Conversely the neighbors have been using their
| resources efficiently, they may have been around for a very
| long time, and they are operating close to their core region.
| The expansionist civilization will get in a fight eventually,
| and it will lose. Even if it doesn't get defeated so utterly
| that it is forced to stop expanding, eventually it will just
| encounter another civilization that will stop it from
| expanding.
|
| The only scenario where continuous expansion is possible
| without FTL travel is if one of the very earliest
| civilizations in the universe has an inexplicable drive to
| expand and does so fast enough that no other civilization can
| arise fast enough to snuff out all possible competing
| civilizations in their infancy. That we have reached this
| point in our technological advancement long before a non-FTL
| civilization could expand throughout the visible universe
| strongly suggests such a scenario is impossible.
|
| [0] Some people may feel inclined to bring up Von Neumann
| probes - craft which travel to other star systems, repilicate
| themselves several times over, and then launch more such
| probes to more solar systems, thus allowing for exponential
| growth. This technology doesn't actually make expansion any
| faster though. Building a probe at A, sending it to B, where
| it builds a second probe, and then sending that to C will
| always be slower than building two probes at A and sending
| one each to B and C directly. There is also no benefit to
| longevity - building a new probe is equivalent to replacing
| every component of the original.
| bserge wrote:
| We _are_ robots. Pretty advanced, too. If only we were able
| to sudo shit :D
| rsynnott wrote:
| > If you look at the realistic reach of the signals of human
| civilization, it's a few tens of lightyears at best.
|
| And probably getting smaller every year. We don't have as many
| giant multi-megawatt radio transmitters as we used to. Quite
| conceivably it could be ~zero in a few decades, as everything
| goes fibre and cellular.
| giantrobot wrote:
| Even our multi-megawatt transmitters being detectable for
| tens of light years is largely a myth. Omnidirectional
| broadcasts need to be powerful just to be detected several
| _miles_ away thanks to the inverse square law. Most powerful
| TV and radio transmitters won 't be detectable too far
| outside the solar system.
|
| It takes a lot of power (or a highly directional antenna) to
| send a detectable signal detectable light years away. The
| only unintentional signals we generate are high power weather
| and military radar. Those are very tight beams that sweep the
| sky. Any interstellar eavesdropper would need to have the
| beam sweep over them to detect it. Even then it would be a
| transient signal with no guarantee of repetition since
| everything is it motion.
|
| It would be like us being a mile apart in the blackest of
| night and you swinging a laser pointer around. Even if I'm
| looking specifically for you and have a general idea where
| you are the odds are vanishingly small your laser pointer
| will happen to be visible to me. You'd have to be
| specifically pointing it at me to even have a hope of me
| seeing it.
| Ekaros wrote:
| And they stop being trivial to decode like AM or FM was. How
| we reach those higher speeds makes whole thing much harder to
| get anything out of.
| aaroninsf wrote:
| Observations or assumptions about the presence or prevalence of
| life which take as a premise that we could detect them are IMO
| meaningless.
|
| In particular, work like this makes assumptions about what it
| means to be "loud" which contain what amounts IMO to a profoundly
| inane belief that advanced civilizations would employ
| communications that are similar enough to our own that we could
| detect them, or, would leak energy in a fashion we could detect.
|
| Both of these premises are deeply anthropocentric, in specific,
| they extrapolate from our current and 20th c. level technologies
| and understanding of physics, material science, etc., not even
| touching on philosophical matters like the dark forest
| hypothesis,
|
| which are so myopic as to be comical.
|
| Idle comment, sometime in the last year or so there was a
| detailed write up of a zero-day no-touch exploit for the iPhone,
| which included a nice tour through the wireless stacks and hacks
| Apple uses to do things like proximal device detection and
| networking.
|
| What struck me at the time and continues to inform my opinion on
| these SETI questions is,
|
| without the frame for understanding the why- and how- going on in
| the iPhone,
|
| the scale of effort it would take a naive investigator to build a
| basic model of what was going on and why, is already at the
| threshold of human comprehension.
|
| While in this specific case what's at issue is EMF using crudely
| comparable encoding schemes,
|
| the point is simply that even knowing about various obvious ways
| of encoding binary information for transmission in a noisy
| environment,
|
| the active signal(s) are already close to the edge of discernible
| from noise, especially complex but true noise.
|
| I.e., even in the EMF domain, we're already for fungible consumer
| goods dealing with multiple frequency-hopping handshakes and
| sniffs and stochastic back-off and retry and error correction.
|
| But there is no good reason to assume some other civilization at
| some other level of advancement would have any use for EMF. There
| are even with known technologies all sorts of exotic, more
| efficient, more targeted, ways of doing long-distance
| communication. Helically polarized lasers come to mind...
|
| Anyway. I think the authors of these things need to be a lot more
| humble about their presumptions, or at minimum, spell them out
| plainly...
| seph-reed wrote:
| I remember seeing somewhere that witnessing the cosmic radiation
| of the big bang is something we have a fairly lucky time-slot to
| be able to do.
|
| If that's the case, _and we 're early to the universe,_ it seems
| like the kind of data we should try to make sure survives beyond
| us.
| merpnderp wrote:
| Talk about lucky, the Earth will only be habitable by most life
| for another 500 million years. We showed up in the last 10% of
| Earth's (habitable) life. If evolution would have zigged
| instead zagging, we'd never have been at all.
| Reason077 wrote:
| > _"We showed up in the last 10% of Earth 's (habitable)
| life."_
|
| While the Earth has hosted microbial life for about 3.7
| billion years, it was only about 2.3 billion years ago (the
| GOE) that free oxygen started to accumulate in the ocean and
| atmosphere, making complex multicellular life possible.
|
| So we're probably in more like the last 20% or 25% of the
| habitable period.
| jandrese wrote:
| It doesn't seem all that likely that we're just too early. The
| planet was stuck with dinosaurs for hundreds of millions of
| years.
| bserge wrote:
| Maybe someone did write "Don't be a cunt" using a bunch of
| stars and we just can't read it :D
| cletus wrote:
| Given these two constraints:
|
| 1. The speed of light is a hard speed limit. This means there's
| also no cheating with warp drives, other forms of FTL, crossing
| dimensions, parallel universes or time travel; and
|
| 2. The laws of thermodynamics as we understand them hold true.
|
| then the outcome of spacefaring civilization I believe is
| generally inevitable. That is, the ultimately limiting factor is
| energy and mass.
|
| The easiest way to get both is with Dyson Swarms. This requires
| no new physics and no exotic materials.
|
| If so, then a galaxy-spanning civilization is going to be
| completely obvious from a million light years away from the
| spectrum. Why? Because a full Dyson Swarm would have a very
| unique spectrum, specifically very little visible light and a lot
| of IR. That's just basic physics. The only realistic way to get
| rid of heat in space is to radiate it away and the wavelength of
| that is a function of temperature.
|
| This is discussed in the context of the Fermi Paradox, which has
| the advantage that you don't need to determine what every alien
| civilization does, you just need to know if there are any
| exceptions.
|
| Example: if there were 1000 spacefaring civilizations in the
| Milky Way, what are the odds that all 1000 of them (assuming they
| were within out light cone) would remain quiet or hidden? Couple
| that with mass and energy ultimately being limited then there is
| a strong incentive and advantage in becoming as large as
| possible. So even if 99% of civilizations remain quiet, the 1%
| will still make themselves visible.
|
| Additionally, on the notion of hidden civilizations in
| particular, it's essentially impossible to remain hidden to a K2
| or K3 civilization so there's really no point.
|
| This is what gives me confidence that the Milky Way isn't teeming
| with spacefaring life. In fact I consider it much more likely
| we're the only such civilization in the Milky Way (within our
| light cone).
| jjk166 wrote:
| > Couple that with mass and energy ultimately being limited
| then there is a strong incentive and advantage in becoming as
| large as possible.
|
| Unless you can transmit power over infinite disctance without
| loss, you get diminishing returns as you expand. Eventually the
| amount of energy you can beam back from a new dyson swarm does
| not justify the cost of building a new dyson swarm. There is no
| incentive to expand beyond that point. For reasonable
| engineering estimates, such a range is still very small on
| galactic scales.
| jandrese wrote:
| How can we be sure that something we have classified as a Red
| Dwarf star isn't a Dyson Sphere? All of the energy of the star
| has to be vented eventually, so a Dyson Sphere should glow like
| an end of life star that has expanded to the diameter of the
| Sphere.
|
| Also, how do you tell the difference between a solar system
| full of orbitals vs. a young solar system that has not had the
| orbital lanes cleared by planets?
| cletus wrote:
| I don't believe that any Red Dwarf could be mistaken for a
| full Dyson Swarm. Some people more knowledgeable than me have
| put a lot of thought into the science of this. You can
| probably find a more satisfying answer.
|
| As for the second part, that's easy. There are two key
| differences:
|
| 1. Young solar systems are around young stars and young stars
| are... young. We can typically age stars, particularly those
| close by; and
|
| 2. A protoplanetary disk is, well, a disk. A full Dyson Swarm
| is a sphere. To be clear, it's not a rigid sphere, it's just
| a collection of orbitals that end up occluding the star they
| orbit in the same way as small water droplets form a cloud or
| fog.
|
| Alsos I suspect that a protoplanetary disk, even if we're
| directly on its plane, won't be as dense as a Dyson Swarm.
| PeterisP wrote:
| I don't know if we can tell it for any particular star, but
| we can reason about large numbers of stars. We have a decent
| model of how stars must age, given their mass and
| composition; we have a decent model of how that composition
| must have evolved as the universe ages, so if there were
| _many_ Dyson spheres around then I think that should be
| observable as there being "far too much" red dwarfs compared
| to how many we should observe.
| JakeTheAndroid wrote:
| > Example: if there were 1000 spacefaring civilizations in the
| Milky Way, what are the odds that all 1000 of them (assuming
| they were within out light cone) would remain quiet or hidden?
| Couple that with mass and energy ultimately being limited then
| there is a strong incentive and advantage in becoming as large
| as possible. So even if 99% of civilizations remain quiet, the
| 1% will still make themselves visible.
|
| I am not sold on this math necessarily. When you ask "what are
| the odds?" what is that based on? How do we derive these odds
| at all? We know nothing about how these civilizations would
| evolve or what their values would be. So how can we assume that
| out of 1000 that 1% would be visible based on the odds? This
| sort of assumes that the Drake Equation is accurate, when the
| last few parts of that equation are complete guesses.
|
| > Additionally, on the notion of hidden civilizations in
| particular, it's essentially impossible to remain hidden to a
| K2 or K3 civilization so there's really no point.
|
| And maybe this is the difference. Maybe all 1000 are visible to
| K2 or K3's because it doesn't matter. But equally all 1000
| aren't visible to K1's. We are so far away from K2 that I see
| no reason to speculate on the likelihood of this since we have
| literally no basis for this other than some fun thought
| experiments. And all of this is based on how we view ourselves
| and apply those same traits to beings we have never met and
| possibly can't even imagine.
|
| This is simply so far out of our grasp to intelligently
| speculate on, I tend to just avoid doing it.
| genghisjahn wrote:
| I _think_ it was Michael Crichton who said something like,
| "An equation whose variables can mean anything, means
| nothing."
| genghisjahn wrote:
| Here it is:
|
| As a result, the Drake equation can have any value from
| "billions and billions" to zero. An expression that can
| mean anything means nothing. Speaking precisely, the Drake
| equation is literally meaningless, and has nothing to do
| with science
|
| https://stephenschneider.stanford.edu/Publications/PDF_Pape
| r...
| openasocket wrote:
| Are we sure we aren't seeing signs of alien life? I mean so
| much of astronomy is based on just observation, is it possible
| some phenomenon we observe is actually the result of an alien
| civilization and not natural?
|
| Sure, we haven't seen a Dyson swarm, but it's not like we've
| been looking super hard, and we're assuming that a Dyson
| swarm/sphere is practical to make and build. If a civilization
| were to develop a way to, say, directly convert matter to
| energy, the Dyson sphere/swarm is actually the less efficient
| option.
| goatlover wrote:
| It's possible of course, and every so often some new weird
| anomaly is detected, and aliens are suggested. But mostly a
| natural explanation is found. The WOW signal and Oumuamua are
| one of the few exceptions, but natural explanations have been
| suggested for both.
|
| The thing is we know about natural phenomenon. We don't know
| whether aliens exist and are detectable. Occam's razor would
| favor existing natural explanations. Stars, planets, comets
| and what not are common throughout the universe.
| rthomas6 wrote:
| > very little visible light and a lot of IR.
|
| That sounds just like a brown dwarf. How would a Dyson swarm
| look different?
| wolfram74 wrote:
| TLDR: a bright infrared source is differentiable from a dim
| infrared source.
|
| If (big if) you can be confident about the distance of the
| object, that'll help tell you the total power output. If you
| have total power output and the black body spectrum, you can
| gauge it's size. A brown dwarf is, notably, small. If you
| took Sol and put a dyson swarm around it, the eventual power
| output would stay the same, just shifted colder as the light
| is now the waste product of all the industrial activity we
| did with it (minus any anti matter or magic matter
| fabrication we did) as opposed hot plasma collisions.
| lrem wrote:
| How can you get that kind of confidence? I imagine a
| slightly more advanced civilisation than ours can send a
| telescope far enough to use parallax. Are there better
| options?
| PeterisP wrote:
| It's not about measuring "size" by looking at width, but
| rather by looking at the total power emitted (for which
| you need essentially just the brightness and distance)
| which gives you the size (mass) of the star. So the OP's
| point seems to be that a Sol-mass star with a Dyson
| sphere may have the spectrum like a brown dwarf, but it
| would have the total emission quantity many, many times
| larger than a brown dwarf can have.
| rsynnott wrote:
| So I think where this idea runs into problems is assuming that
| people actually want or need a Dyson swarm.
|
| The sun puts out 3.846x10^26W. Let's assume a Dyson swarm
| manages 10% capture efficiency, and a future population of 100
| billion. That would result in every person having access to
| 384TW, or about 25 times Earth's total power consumption.
|
| Clearly, that's far too much power for any reasonable use-case,
| so at that point you're talking about either a far higher
| population (quadrillions) or far smaller collection area.
| Earth's population seems to be destined to cap out at about
| 9bn, and the trend away from population growth is most
| pronounced in highly developed energy-hungry countries. So
| _we're_ probably never going to need a Dyson swarm, anyway...
| cletus wrote:
| First, you'd be surprised how many people we can support.
| Like we could likely support more than a trillion people on
| Earth. The population of a full Dyson Swarm around our Sun
| likely caps out in the quadrillions, possibly quintillions.
|
| Second, it's entirely valid to ask the question of whether
| we'd ever reach such populations. This is of course unknown.
| As a solution to the Fermi Paradox, the idea of reaching a
| steady state (or even shrinking to a fragment) seems
| unsatisfying as a 100% outcome. Once again, it only takes 1
| to keep growing and become detectable.
|
| A lot of things are likely to change in the next millenium,
| for example:
|
| 1. I expect we will live much, much longer than we do now;
|
| 2. Automation will increase to the point where labour is
| highly unlikely to be the limiting factor in any kind of
| industrial output. That leaves resources and energy as the
| limiting factors. Well, resources are just a proxy for
| energy. There are several rocky bodies in the Solar System
| that could, given enough energy, provide unimaginable amounts
| of raw materials;
|
| 3. Despite the wealth of developed nations, we are still
| living in an era of relative resource scarcity. Individuals
| in developed nations are certainly generally more prosperous
| than those in developing nations but it's expensive to raise
| children in developed nations the way most parents want to
| raise them: paying for education, housing, etc.
|
| I'm not comfortable making the prediction than the modern
| trend of having relatively few children per individual in the
| developed world will continue into an era of longer lives,
| far more abundance and being freed from the need to work
| their entire lives to set up those children.
|
| Lastly, there are some very obvious applications for huge
| amounts of energy, for example:
|
| 1. Extracting resources;
|
| 2. Vast amounts of computing power. What would you do with
| this? We haven't been good at predicting this other than to
| say that more bandwidth and more computing power has thus far
| always found applications that people want. One obvious one
| is I suspect we'll have VR worlds that people will basically
| live in on a scale we can't possibly yet imagine;
|
| 4. Interstellar travel; and, of course
|
| 5. Cryptocurrency mining. :)
| jstanley wrote:
| > The only realistic way to get rid of heat in space is to
| radiate it away and the wavelength of that is a function of
| temperature.
|
| Then why would it definitely be IR? Couldn't a different form
| of intelligence thrive at a completely different temperature,
| and rely on elements that have phases that are useful to them
| at different temperatures?
| cletus wrote:
| So the wavelength of black body radiation is called Wien's
| Law [1]. If you look at the electromagnetic spectrum [2], the
| IR spectrum is 25 mm to 2.5 mm.
|
| Compare those two and you'll see pretty much any reasonable
| range of temperatures has a heavy IR element.
|
| Some things to consider:
|
| 1. Tungsten has probably the highest melting point at ~3700K.
| It seems unlikely that complex matter of any kind can
| realistically survive at such extreme temperatures;
|
| 2. Heat above a certain level can itself be used to generate
| energy in a straightforward fashion. This itself will
| generate waste heat, most likely at a much lower temperature.
|
| As an aside, recycling heat is often raised as an objection
| to the IR signature issue with Dyson Swarms but that ignores
| thermodynamics. Let's say heat recycling for a star like the
| Sun is 90% effective then that's still 10% energy lost and
| 10% of the Sun's output is still massively significant.
|
| If there's perfect recycling, well that ignores entropy.
|
| [1]: https://en.wikipedia.org/wiki/Wien%27s_displacement_law
|
| [2]: http://labman.phys.utk.edu/phys222core/modules/m6/The%20
| EM%2...
| jstanley wrote:
| Good info, thanks!
| peakaboo wrote:
| I think it sounds daft to think speed of light is a hard speed
| limit, and there is absolutely a way to "cheat".
|
| Because aliens are here, and they certainly didn't travel at
| the speed of light to get here. That doesnt work at all. It's
| way too slow.
|
| My bet is they are extracting energy from space itself, what we
| call vacuum and we think there is nothing there. And I also
| think the speed of light only applies to things in our physical
| universe. Frequently these alien ships blink in and out of our
| reality. There is much we don't understand as humans.
| merpnderp wrote:
| It's not impossible that something like solving the
| cosmological constant problem could lead the way for harvesting
| zero point energy. If supersymmetry exists, which is a big if,
| physics would become a whole lot more exciting.
|
| This would make Dyson Spheres unnecessary for advancement on
| the Kardashev scale.
| T-A wrote:
| > harvesting zero point energy
|
| Even if that were possible, it's only 6e-10 J/m^3 [1].
|
| Want to keep a 10W LED light on? That's 10 J/s, so you need
| to extract all dark energy from 17e9 m^3 of space (roughly a
| cube with a side of 2.5 km) every second.
|
| [1] http://www.astronomy.ohio-
| state.edu/~ryden/ast162_10/notes41...
| mattmanser wrote:
| Seems like a good theory, but when I read something like this
| it always makes me think about any of the sci-fi I've read that
| was written 50-75 years ago.
|
| They're also full of what were at the time good theories, but
| that are now so wrong it often makes reading the story
| difficult, even with my fairly rudimentary modern astrophysics
| knowledge.
|
| In all honesty I think it's more likely any sufficiently
| advanced civilization capable of interstellar travel has
| probably descended entirely into virtual reality or a
| singularity.
|
| I mean, what would you prefer? Being the star of your own
| personal VR space, the next Malcolm Reynolds, space cowboying
| around where you are the entire focus of that reality. Or
| schlepping it over to another star in a generation ship or
| whatever where even if you were somehow still alive when it
| arrived, you'd be landing on a planet that will probably
| instantly kill you.
| jerf wrote:
| The thing about the "they'd just descend into VR" is that you
| must explain why _one hundred percent_ of all entities
| capable of doing that decide to do that.
|
| Moreover, even if you do descend into VR, if you have a
| civilization capable of safely doing that, you need to
| explain why _100.0000...%_ of them never say "hey, I sure
| could have a lot more VR resources all to myself if I just
| sent this probe over to that star system over there and
| converted it into computronium".
|
| By the time you get to this level, you don't need to worry
| about "planets that will instantly kill you".
|
| Some sort of "singularity" where they escape our universe
| would explain the emptiness of the sky. However, every year
| the places where such a thing could hide in our physics gets
| a bit narrower, and we have literally zero reason right now
| to believe that such a thing is possible. I have no problem
| speculating, but I prefer to keep the grounded and ungrounded
| speculation clearly delimited, and right now this is
| definitely on the ungrounded side.
|
| (Side not, not targeted at you mattmanser but just to prevent
| me posting another message, it's _really_ tedious to attack
| someone engaging in grounded speculation by pointing out that
| ungrounded speculation exists. Yes, it 's _possible_ that
| humans are just uniquely stupid and there 's some easy
| mechanism to create and escape into infinite energy
| subuniverses and half the planets in the universe have had
| dozens of alien civilizations already do so, it's _possible_
| that aliens are using energies we 've never even heard of to
| communicate, and it's _possible_ that psychic waves are
| radiating right through us this very second telling us how to
| do it, but that 's ungrounded speculation. It doesn't mean
| that we must therefore give up all grounded speculation
| because "what if, like, the aliens are all psychics that
| escaped into the ninth dimension? you can't _prove_ they aren
| 't, man.")
| BrandonM wrote:
| _> I mean, what would you prefer?_
|
| I would not choose to be the star. Observing substance
| (ab)use and suicide among celebrities and the affluent, it
| seems clear that a "starring role" in life is not an
| automatic ticket to happiness or fulfillment.
|
| For me at least, a lot of the meaning in life comes from
| dealing with cold hard reality. Updating my strengths and my
| belief systems to be more aligned with a disinterested
| external world. Connecting with, learning from, and sharing
| with other humans what it all means and what it's like to be
| part of this whole thing, to get a more complete
| understanding of the human experience.
|
| Consider--if we were one unified consciousness with total
| understanding existing in absolute bliss, what would there be
| to _do_ , to discuss? We might produce a limited world like
| our own to make existence more meaningful.
| elcritch wrote:
| StarTrek TNG's "Q" had that problem. They'd effectively
| ascended but were bored out of their minds. Well rather one
| of them was. It was one of my favorite plot elements.
|
| Even in a virtual reality (perhaps especially in VR?) I'd
| fear that a single instantly connected human society would
| stagnate pretty quickly.
|
| At least sub-light speed travel and communications limit
| would allow future human colonies to grow independently
| rather than our increasingly homogeneous worldwide consumer
| culture.
| hungryforcodes wrote:
| No it would probably be a lot more like TikTok or other
| social media. Addictive at first and then most likely
| economically driven as well.
|
| Imagine being able to deliver REAL experiences as ads:
|
| "TRY our new toothpaste. Really!"
|
| So like everything in technology we will just kind of
| evolve into it without even noticing until it's too late
| like Facebook or some such.
| bserge wrote:
| Both tbh. Send the robots (which could even be biological) to
| do real life work and just chill in VR.
| cletus wrote:
| There are several differences between these old predictions
| and now:
|
| 1. We're now assuming based on the limits of known physics
| rather than the expected limits of technology. My father told
| me he once read a book that said it was impossible to go to
| the Moon because it would take 750 years to get there. The
| speed of light was known at that time but assumptions were
| made about the limits of acceleration and velocity that
| weren't grounded in science;
|
| 2. Things like the rocket equation are important.
| Specifically, the reaction mass problem. Even more
| specifically, the only way for an independent body to
| accelerate in space that we know of is by expelling mass (or
| energy). You need to carry that mass and this quickly becomes
| inefficient.
|
| A good example of this is how people have recently started to
| say "if we just accelerate at 1G we can get to Alpha Centauri
| in a few years". 1G acceleration sounds easy but it's not.
|
| So how would you travel between stars? I think it most likely
| that you'd use a ton of energy to accelerate (or decelerate)
| a vessel with lasers on a solar sail. Why? Because energy
| from a star is abundant and cheap and it doesn't require
| carrying reaction mass.
|
| If you accept that, then the need for Dyson Swarms becomes
| more obvious.
|
| 3. Breaking the 2 assumptions I listed makes spacefaring life
| more common not less. By this I mean we only really need to
| consider a million light years (of light cone) because of the
| speed of light. If FTL or even time travel were possible,
| then you need to consider a volume of spacetime orders of
| magnitude larger.
| mattmanser wrote:
| I think it's more that we don't know what we don't know.
|
| That's the thing that usually trips us up.
|
| Also, on a more human level, who's going to even pay/bother
| with these swarms? What will they achieve?
| Calavar wrote:
| > _My father told me he once read a book that said it was
| impossible to go to the Moon because it would take 750
| years to get there._
|
| A bit of a tangent, but that seems absurd even based on
| knowledge from hundreds of years ago. The moon is about
| 250,000 miles away, so the 750 years figure assumes a speed
| of less than 1 mile/day. And a quick google search suggests
| that we've had reasonable estimates of the distance to the
| moon since about the 2nd century BCE.
| SubiculumCode wrote:
| why not both?
| jdkd8 wrote:
| Or every species consumes its planets resources on phones and
| cars, imploding the environment before the necessary
| engineering feats to get them to the stars come along.
|
| My money is on it being too infeasible engineering wise due to
| resource exhaustion just building the infrastructure to get
| there. The carbon feedback loop creating disposable junk is
| destabilizing stable human climate.
|
| I lean towards the idea we'll have to move away from
| industrialism at the scale we apply it today.
|
| Perhaps synthetic drugs can grow neuron structure that mimics
| the experience. Or helps acquire muscle memory from skills
| based work.
|
| Trip balls on the couch for 20 minutes and live life believing
| I just got from Mars Base 1 and have Zappa opening for me
| wouldn't be so bad.
| fallingfrog wrote:
| One issue here is that there's no economic reason for the home
| planet to mount the sort of resources it would take to fund an
| interstellar trip. Stars are farther away than you think. The
| only way I can see that it would happen is for religious reasons,
| if the belief system of the religion required them to do it.
| Because there's no economic reason.
|
| The other issue is that it's not clear how long technological
| civilizations last. We might be close to exhausting our own
| planet just 150 years after the invention of radio. Maybe
| technological civilizations bloom in the dark like beautiful
| flowers, then burn out quickly before they can spread to other
| systems.
| mFixman wrote:
| I never understood these kind of analyses that talk about aliens
| reaching "humanity's level" like it's inevitable or somehow
| special.
|
| We could blast radio waves with ABBA songs into space to find
| whether there are other Swedish-speaking civilizations, or
| whether we are alone in the Universe. We don't because it's silly
| to think of the Swedish language as a necessary step for
| "advanced life".
|
| Why do we think that human-like intelligence is special?
| astroalex wrote:
| This seems a bit backwards to me.
|
| It's only futile to blast ABBA songs (or other human-like
| signals) into space if we think human-like intelligence is
| special.
|
| It's precisely because we believe human-like intelligence is
| _not_ special that blasting (or listening for) space signals
| makes any sense. The assumption is that other civilizations
| will converge on some of the same technology that we've
| developed and recognize a patterned signal when they see one.
| mFixman wrote:
| > The assumption is that other civilizations will converge on
| some of the same technology that we've developed and
| recognize a patterned signal when they see one.
|
| Why would anyone think that?
|
| No other species in the history of the Earth has the ability
| to create human languages. Nobody outside the tiny group of
| 0.1% of humanity can speak Swedish. No single rock we've
| observed outside our planet can even understand the concept
| of a word like "Laderlappen" or "Knullruffs".
|
| Those 10 million people are alone in the Universe as
| developers and speakers of Swedish just like these 7.9
| billion people are alone in the Universe as developers and
| users of human-like intelligence.
|
| Blasting signals into space is the same as singing ABBA songs
| really loud: maybe a sci-fi civilization of Klingons who
| speak a Swedish-like language could understand it, but in our
| Universe there's no chance that some extraterrestrial thing
| will converge on the same languages or technologies as we
| did.
| T-A wrote:
| Radio is currently the only realistic means of interstellar
| communication at our disposal, so we listen for (and
| sometimes send [1]) radio waves.
|
| In other words, we look for aliens equipped with radio
| telescopes, because they are the only kind we can hope to
| find.
|
| The choice of language follows from that. To have
| technology at the level of radio telescopes, you need to
| understand physics at mid-20th century level (or higher).
| To understand physics at that level, you need math at the
| level of calculus and differential equations.
|
| So we look for, and sometimes send, messages which start
| with simple mathematical relations and then build up to
| physical quantities.
|
| [1] https://en.wikipedia.org/wiki/Arecibo_message
| arbitrage wrote:
| > We estimate that loud alien civilizations now control 40-50% of
| universe volume, each will later control ~10^5 - 3x10^7 galaxies,
| and we could meet them in ~200Myr - 2Gyr.
|
| This is utter nonsense.
| VortexDream wrote:
| In what way is it nonsense?
| icapybara wrote:
| Extraordinary claims require extraordinary evidence. This
| statement, with absolutely no hard evidence, is asserting
| that aliens exist and in fact control 40-50% of the universe.
| Furthermore it is also fundamentally untestable as it
| includes the convenient disclaimer that "we will meet them in
| 200 Myr - 2 Gyr."
|
| "I have never seen a unicorn nor do I have any evidence they
| exist. However, their existence seems logical, and therefore
| I estimate that they control 40-50% of the universe volume,
| each will control ~10^5 - 3x10^7 galaxies, and we could meet
| them in ~200 Myr - 2 Gyr."
| nathanmcrae wrote:
| The preceding sentences explain the model that generates
| that estimate, including the 200 Myr - 2 Gyr number; that's
| not a case of hand-waving.
|
| Is your issue with some aspects of the model or with the
| idea of trying to model this at all?
|
| It's certainly early days for this theory, but it's worth
| not dismissing out-of-hand.
| icapybara wrote:
| My issue is: can this model make testable predictions
| within our lifetimes? It doesn't seem that way.
|
| Even models of the far future and the distance past of
| the universe are held to standards of evidence and
| testability. Why shouldn't this one be?
| nathanmcrae wrote:
| Yeah, that's an important point, but that seems to be an
| issue with the subject of study rather than this
| particular theory. At least their model has very concrete
| and explicit premises that could be used to reject it.
| Particularly the 'hard steps' model of evolution: I don't
| know how widely accepted that is (genuinely don't, it may
| be accepted) and, if it is in time rejected by the
| scientific community then that would discredit--if not
| falsify--the theory.
| thevardanian wrote:
| The idea that only testable predictions are valid is...
| short sighted. Seriously considering extraordinary ideas
| with as much rigor as possible, with the tools available,
| is something that has propelled science. If not then
| ideas about the moon would have been dead in the water.
|
| If anything this kind of "rationalism" only conceals
| dogmatic ideas about what is or isn't possible..
| Reason077 wrote:
| Feel free to post your own estimate. Please include your
| reasoning.
| h2odragon wrote:
| The estimates here are as good as anyone can make, I think.
|
| Of course we can choose our postulates and come to any
| conclusion we want, as they have done here. When we've only
| really got conjecture and guess and golly to work with, it's
| all going to be a bit of an exersize in intellectual
| masturbation.
|
| Quibbles about methodology are just comparing techniques:
| long v short stroke, with or without twist, etc. The input
| and the output is still the same and of the same value.
| dogma1138 wrote:
| You don't need your own estimates to call BS on theirs.
| Including simply on the premise of the volume of the
| universe, most of the universe is an empty void. Even if you
| allow somehow for the traversal of intergalactic void in your
| local clusters this alone should put a much more serious
| dampening effect on the expansion of any given species.
|
| It also assumes that species can even get to the
| technological level required for galactic and then
| intergalactic expansion and maintain that level pretty much
| indefinitely.
|
| But then again this isn't a research paper or even a
| particularly serious statement.
| jefftk wrote:
| _> this isn't a research paper_
|
| It's the host organization's announcement for
| https://arxiv.org/pdf/2102.01522.pdf
| datavirtue wrote:
| You need energy mastery. Ability to harness infinite or
| practically infinite energy available freely. With this
| understanding and power you can innovate further, perhaps
| gaining the ability to create matter and one day transport
| it along the fabric of space outside the constraints of
| existing matter (time).
|
| Then again, maybe true advancement means losing interest in
| manipulating matter, turning inward and finding or
| developing enhanced mental states that let us see things
| clearly without understanding everything empirically.
|
| Perhaps the ultimate goal is to be at peace and even joyful
| at living and dying. Humans are still very believe-y,
| angry, outward and confused.
| dogma1138 wrote:
| If you attain that level of technology why do you need to
| go anywhere? If you gain access to infinite or near
| infinite energy source it seems like it would be a waste
| to use that energy to cross the intergalactic void or
| even outside your solar system or star cluster since you
| could simply use it to build w/e you need anywhere in
| space so you might as well stay put.
| thevardanian wrote:
| Resilience. Being multi-planetary means your species is
| fundamentally protected from almost all catastrophic
| events. Having presence among multiple stars systems
| would mean not even planetary level destruction would be
| a threat to a species. As it currently stands humans are
| still very much in a precarious situation as an errant
| asteroid, even a decade away, could mean game over for
| all of humanity.
| titzer wrote:
| I find these kinds of analyses to be hopelessly oversimplified.
|
| First of all, we are talking about predicting the actions of
| _superintelligent aliens_. We aren 't talking about slime molds
| or a bacterial infection, but beings with _more intelligence than
| us_ , like orders of magnitude more complicated reasoning
| processes. They are effectively unpredictable, because if they
| weren't, wouldn't we be just as smart as they are? That level of
| intelligence comes with new levels of reflectiveness that are
| frankly not accessible to our weak brains. Like, maybe after
| reaching the next level of enlightenment, they decide that
| expansion throughout the universe like a worm is not actually
| what they _want_ or that is what is _good_ for the universe?
| Maybe they decide to rather study the universe and not interfere,
| the way biologists study, say, apes, without wanting to disrupt
| their natural behavior with their presence? Or maybe
| superintelligent beings find a way _out_ of our universe, and
| pass into another dimension (cyberspace? black holes?
| disappearing through quantum foam? heaven?). Or maybe something
| else insane happens, like being superintelligent inevitably makes
| you completely terrified of everything, because you realize how
| powerful _other_ aliens are and your calculations unequivocally
| show it 's safer to stay at home and fart around doing the super-
| intelligent analog of baking chocolate-chip cookies? Not being
| superintelligent, we are like ants trying to contemplate human
| civilization. We have no context or experience, and we simply
| don't have the mental capacity to even _imagine_ what we don 't
| know.
|
| Second, these probabilistic models are so fundamentally stupid.
| It's impossible for us to reliably estimate the probability of
| any event that's happened only once (without reasoning about the
| process that gave rise to that event), as we cannot estimate
| posterior probabilities without lots of samples. And humans on
| Earth have a massive chain of single-occurrence events that all
| seem to be absurdly improbable. Besides that, and perhaps even
| because of that, it's not even a foregone conclusion that our
| universe even selects from the middle of the distribution (i.e.
| is not _biased_ ). We could perfectly estimate the shape of a
| probability curve and yet live in a universe that stubbornly
| selects from the end of the distribution, all the time. All of
| our math could be totally right, but crazy shit just keeps
| happening.
|
| Third, the anthropic principle is a total bitch. It means that we
| will _never_ be able to estimate probabilities of events that
| were required to create us, because no matter how improbable they
| were, if they didn 't happen, we're not even here to argue about
| it. If there are infinite universes (a multiverse, see Tegmark),
| then forget this whole mathematical sophistry, because then there
| is no need to live in some "average" universe; we can easily live
| in some stupidly improbably snowflake universe that has the 90
| trillion improbable things that make apes possible; infinity
| doesn't care.
| brian_cloutier wrote:
| Your comment deserves a much longer response than I can give
| it, but you seem to be saying that it's impossible to know
| anything with any certainty, and that is absolutely true. I'm
| sure all the authors of this work would agree with you.
|
| Coming to conclusions/guesses requires starting with some
| assumptions about about how the universe works. It's important
| not to lose sight of those assumptions and very important to
| have a discussion about how likely each assumption is to be
| true. So to the extent that anyone is saying "this is
| definitely how the universe is", I wholeheartedly agree with
| you.
|
| However, it feels like you're being a little too epistemically
| nihilistic here. This kind of speculative work always starts
| without confirmation or any particular reason to believe it
| beyond how well it matches the curve it was fit to.
|
| To quibble with a particular, this work doesn't attempt to
| predict the actions of super-intelligences, it's not making the
| claim that most civilizations will be "grabby", it's making
| predictions about what will happen under the assumption that
| some subpopulation of them decides to become grabby.
| titzer wrote:
| I am not being nihilistic, I am being realistic. We really
| can't predict the actions of superintelligence, full stop.
|
| Here's what I mean. What makes the lights on your router
| blink? Usually, it's packets going in and out. At a coarse
| level, if your computer is doing something on the internet,
| the lights are gonna be blinking. But now increase the
| resolution, from seconds, to milliseconds, to microseconds,
| to nanoseconds. At a nanosecond level, whether the LED is on
| or off depends on whether a packet is going over the wire
| _right this nanosecond_. Whether a packet is earlier or later
| by a nanosecond is influenced by a _bazillion_ variables: the
| router 's internal state, its own operating system's
| scheduling, whether the devices connected to _it_ are sending
| packets at it, dragging in their state, their scheduling,
| their programs, packet queues, etc. Gigabytes of state,
| changing nano-second to nano-second. Oh, and it 's connected
| to the internet. When does the internet decide to send a
| packet to this router? If those are faster or slower by a
| nanosecond, it could be due the state along the _entire_
| path, all of which are servicing packets from all over the
| place, decided upon by super-complex distributed systems--
| datacenters full of them. So even the blinking of a router
| LED is connected to a supremely complex causality tangle. To
| understand the blinking nano-second to nano-second, you
| basically have to replicate the details of the entire
| internet. So, if I were to ask you instead to predict what
| will happen tomorrow at 3:33am--will your router be blinking,
| let 's say, fast or slow? Who knows. A DDoS might crop up
| because someone was mad at Amazon, or maybe your OS downloads
| a software update, or maybe you are up watching Netflix, or
| maybe the whole thing is down because nuclear war. It's
| progressed so far from a simple bell curve that probabilistic
| reasoning, I would argue, is useless. And that's just without
| the internet being "intelligent"! Now assume the internet
| knows this prediction game is afoot, and it gets to bet too.
| The whole thing goes off the rails.
|
| No, we can't predict what aliens will do. This paper is a
| mathematical exercise that might apply to bacteria or video
| game characters, not interstellar civilizations.
| qwytw wrote:
| How can you predict that a "superintelligence" does or
| could even exist then?
|
| To be fair, based on your description, assuming is is not
| completely random, you can still build a somewhat accurate
| model that would be able to somewhat accurately estimate
| when and how often the light will be blinking without
| having a full understanding on what exactly causes it.
| nathanmcrae wrote:
| The paper addresses your first point in section 7 'Model
| Rationale'. Essentially, anything that is subject to self-
| propagation is going to tend to expansionism at a large enough
| scale, superintelligence or not. The only thing that would
| prevent this is wide-scale coordination (e.g. a universal
| autocratic government). And if any species did accomplish this,
| they would just be one of the 'quiet' ones.
|
| That's my take, they wrote it better though. That section is
| short, straightforward, and worth reading.
| Gravityloss wrote:
| Interesting points, though the abstract is quite hard to follow.
| I guess it makes sense: 1. aliens spread at a
| certain speed after developing spaceflight 2. they're not
| here 3. there are no spacefaring aliens in the galaxy
| currently
| kenjackson wrote:
| Thanks for that simplification. I didn't get that at all from
| the abstract (as I didn't really follow much of it) :-(
|
| What is "volume appearance" BTW?
| addingnumbers wrote:
| A turtle on the Galapagos Islands in 1450AD could use the same
| reasoning to conclude that no seafaring civilizations existed.
| jandrese wrote:
| It's not a matter of limited perspective, it's a matter of
| the laws of physics. The rocket equation is a harsh mistress.
| Without FTL or reactionless drives the physics of going to a
| distant solar system is absurdly unfavorable. It takes many
| decades/centuries, is a one way trip, and the ability to
| build a self contained self powered ecosystem that can
| survive the entire trip without support. Once you have that
| why bother going to a distant solar system? You have a
| perfect orbital habitat.
| hansbo wrote:
| Yeah, but if humans keep existing for millions of years, then
| the probability for a turtle on the Galapagos Islands to live
| in the time between when humans started seafaring and when
| humans visited the islands would be extremely small compared
| to any other time period.
| addingnumbers wrote:
| Since we know the conclusion to be false, any reasoning
| that would support this hypothetical turtle's conclusion
| that no seafarers existed in 1450 is inarguably an example
| of bad reasoning.
| gpm wrote:
| No, because the turtle is concluding that it's _likely_
| false, not _definitely_ false. There happens to be a
| cosmic coincidence working against the turtle, but that
| doesn 't mean that it was bad reasoning to conclude that
| the cosmic coincidence was very unlikely.
| addingnumbers wrote:
| The turtle is saying with certainty, not likelihood, that
| no seafarers exist, analogous with the explicit
| conclusion (3) in the top level comment
| gpm wrote:
| People are lazy when they speak, it's best to understand
| basically every claim as probabilistic (and meaning
| "almost certainly") even when it isn't stated as such.
|
| Certainly no-one would make the claim that "there are
| (definitely) no aliens in the galaxy" when we can't
| disprove the idea that aliens traveling at the speed of
| light just reached the galaxy (with our current
| understanding of physics). That doesn't mean you can't
| make the claim "there are (almost definitely) no aliens
| in the galaxy (because I just created the most amazing
| telescope ever and looked at every particle of matter in
| the galaxy and there were no aliens there)". The
| principle of charity demands that understand the bare
| claim that "there are no aliens in the galaxy" to mean
| something that is plausible, such as "there are almost
| certainly no aliens in the galaxy".
| addingnumbers wrote:
| A line of reasoning that tells our turtles something
| totally false doesn't deserve validation for doing it
| with slight uncertainty.
| indrax wrote:
| You have to weight the validity of the reasoning across
| all turtle observers through history. If you reject
| probabilistic reasoning because it sometimes tell you
| things that are wrong, then you have no way to reason
| about uncertainty.
| addingnumbers wrote:
| If your reasoning about uncertainty tells you there's a
| 99% chance something is false while it's true, what good
| is it? All the math in the world won't save you from the
| specious premises in this no-seafarers argument.
| RupertEisenhart wrote:
| That is incorrect. Good reasoning can lead to conclusions
| that are strictly false.
|
| For example, when asked to be more granular, the turtle
| could say 'I reason that there is only a 1 in 10 chance
| that seafaring civilizations exist'. The existence of
| seafaring civilizations doesn't make the turtle wrong in
| this case.
|
| If the turtle concluded that 'there can not possibly be
| any seafaring civilizations, because I don't see any'
| then you could accuse it of bad reasoning.
| addingnumbers wrote:
| > If the turtle concluded that 'there can not possibly be
| any seafaring civilizations, because I don't see any'
|
| The hypothetical turtle did exactly that, loyally
| following suit with the commenter who I replied to.
| jameshart wrote:
| The turtle would be working with considerably less data,
| though. Does he know how old his island is? Does he have
| conclusive evidence of the existence of other islands? Is he
| aware of the similarity or difference of other islands
| compared to his own? Would he be able to observe if seafarers
| were living on a nearby island or does he need to wait for
| them to actually land on his beach? Does he have a reasonable
| estimate for the size of the earth? The amount of ocean? For
| the distribution of islands across the ocean?
|
| Also, since he's a turtle, he doesn't, presumably, yet
| actually know how hard it is to make a boat. The argument for
| determining whether or not you are the only seafaring species
| depends, first, on you having attained the ability to travel
| the seas...
|
| All of that seems necessary before he can conclude whether or
| not he should consider it 'surprisingly late' for his island
| not to have been reached yet by any seafarers.
|
| But the interesting part of the analogy is maybe that the
| turtle might fool himself into thinking he understands the
| parameters well enough to estimate this probability - after
| all, he's paddled around off the beach and even made it to a
| nearby rock - so he reckons he's got a pretty good handle on
| how hard it must be to travel between islands.
| addingnumbers wrote:
| I wonder how I failed to express my position so badly that
| people who seemingly agree with me think they don't.
|
| Ignorance and misestimation of the true underlying factors
| isn't a trait unique to these hypothetical turtles.
|
| Or, perhaps you have a much higher confidence than I do in
| humans' assessment of the factors involved in your
| questions.
|
| I'm saying we are over-confident in the underlying premises
| of our understanding, just like the turtles would be. The
| more of the questions you pose that go partly unsolved, the
| more unsubstantiated the conclusion. Their probability
| calculations are pointless -- garbage in, garbage out. As
| demonstrated by the patent wrongness of their conclusion.
|
| If you are confident that we've got solid answers to the
| interstellar corollaries of all your questions with the
| evidence we can gather at this point, then we aren't on the
| same page at all.
|
| This idea, that our observations of the universe are a
| properly representative sample from which to form
| conclusions about the unobserved universe, makes as much
| sense to me as the thinking-turtles assuming you need a
| small green island to and a thick shell to enable sentience
| because that's what their observations show.
| m3kw9 wrote:
| The incentives and disincentives of exploring other systems is
| largely unknown. There could be huge risks in visiting other
| systems in which your own system of origin could be revealed if
| you happen to find another advanced civilization, I would think
| if a civilization is even predicted to be in a system, it will
| likely not be visited.
| 7thaccount wrote:
| The Fermi Paradox (where is everyone) has been debated for
| decades. There are so many possibilities such as great filters
| (early or late), prime directive, zoo hypothesis, dark forest
| hypothesis...etc etc. I'm sure you're aware of this, but I
| included just in case you wanted to explore in more depth. Some
| really good stuff.
| AtlasBarfed wrote:
| I just heard about the dark forest a couple weeks ago. I
| believe it to be the model we should proceed with for safety.
|
| Assuming FTL isn't possible, the fact that dark energy makes
| large sections of the visible universe fundamentally
| inaccessible is probably a good thing.
|
| Otherwise that is a lot more of the universe that may be
| ahead of us and would stomp us like ants.
| TheOtherHobbes wrote:
| 1. No they don't. Spreading at sub-FTL requires redundant self-
| correcting technology which can run for thousands of years
| without breaking down. This is about as achievable as FTL.
| _Nothing_ lasts for thousands of years in deep space without
| being abraded, fried, nuked, or physically stressed to breaking
| point.
|
| 1b. Assuming you can solve 1. with some kind of magical
| alchemical spares-generating technology that never fails, the
| technology also has to be politically and philosophically
| stable, with reliable and persistent goals. Otherwise you'll
| get offshoots competing with each other. Which may mean
| undermining and perhaps even destroying previous settlements.
| How much independence is enough? How accurate are your initial
| models going to be?
|
| 2. We don't know that for sure. Absence of evidence is not
| evidence of absence. (We do know weird things happen, but we're
| not putting any serious effort into researching them, so we
| don't know what they are.)
|
| 3. There's no need to think about this after 1. and 2.
|
| Edit: to put this in context, you don't need to launch a probe.
| You need to launch a complete perfectly self-reproducing error-
| free space program. Which can also adapt to local resources.
|
| This seems... difficult.
| jandrese wrote:
| If you have #1 you no longer need to go to a distant solar
| system to survive. By the time you have the tech you no
| longer have the need.
| jamesdmiller wrote:
| Hanson doesn't think (2) and (3) follow because of the
| possibility of panspermia. It's possible that our galaxy is the
| only one in a billion light years that has given rise to life,
| but there could, because of panspermia, skill be a high
| probability that a planet in our galaxy outside our solar
| system has life. See this podcast Hanson did with me:
| https://soundcloud.com/user-519115521
| blfr wrote:
| Your podcasts with Greg Cochran are quite possibly the most
| interesting (interesting stuff per minute) audio I've ever
| listened to.
| jamesdmiller wrote:
| Thanks!
| rsynnott wrote:
| I think (1) is probably the main questionable assumption, to be
| honest. Let's take as given that travel faster than light via
| some form of cheating isn't possible. Under that assumption,
| for mass interstellar travel in reasonable time, you would
| require the ability to produce vast amounts of cheap energy
| (either via fusion on the starship, or antimatter produced with
| cheap energy at home and used on the starship, or by some other
| means).
|
| And at that point, where is the incentive to colonize other
| star systems? You're still probably not going to be able to
| move a meaningful part of your population, and if you can
| produce energy that cheaply you can sustain a large population
| in comfort at home.
|
| It's not inconceivable that there are advanced aliens all over
| the place, but that interstellar travel is basically limited to
| probes for pragmatic reasons.
|
| I think when the Fermi Paradox was brought in, there was still
| some lingering Malthusian idea that geometric population
| expansion was inevitable. We now know it very much isn't, at
| least for us. That changes things.
| PeterisP wrote:
| The big issue here is different understanding of "reasonable
| time". The galaxy is very large, and the time spans involved
| are very large, but they are not in the same ballpark of
| "large", the time gaps involved are so much larger. If one
| civilization gets their evolution of intelligent life just 1%
| quicker than us, that's a head start of 50 million years. On
| that scale, "reasonable speed" required to fill the galaxy
| (to use round numbers, 10000 "hops" of 10 ly each for
| 100000ly distance across the whole galaxy) means something
| like a planet launching a single colony ship to a nearby star
| once in 5000 years (and the new colony populating the planet
| and launching another ship in 5000 years, which seems quite
| reasonable). You don't need FTL, you don't need fast ships,
| you don't need many ships, just one generation ship in a few
| millenia moving at 0.01c or even less is amply sufficient to
| colonize all of the galaxy many times over in that time
| range. And if someone was 2% or 3% faster than us, then
| they'd have even more excessive time to swarm the galaxy even
| if they're doing it at snail's speed.
|
| So to explain the fact that the aliens aren't swarming
| everywhere because they can't afford it means accepting that
| either they launching a single generation-ship every 5000
| years is a huge expenditure (which IMHO it wouldn't be even
| with our current economy size, definitely not an issue with
| the tech of 2100 or 2200 assuming at least some growth
| because at that point a Musk-type figure with a wish to "make
| humanity interstellar" would be able to afford it from
| private funds) or that we're the first (only?) life in galaxy
| or that all the aliens before us didn't try to expand, like,
| at all - because getting just one single rich eccentric every
| 5000 years (like a bunch of billionaires here are) would be
| sufficient to make the galaxy swarm with juuust a bit higher
| tech level than ours now.
| Gravityloss wrote:
| Well, maybe "constant speed" is a bad wording.
|
| An example:
|
| We have 1000 stars within the 30 light year radius
| neighborhood. Traveling at Voyager 1 speed, it takes half a
| million years to do a 30 light year trip. [1]
|
| Given another half a million years for bootstrapping at the
| destination for ten more probes, we can send ten more probes,
| 1 million years from the launch of the first one. At two
| million years we get 100 probes.
|
| How many probes do we get in a 11 million years? 10^11
| probes. We have 10^11 stars in the galaxy.
|
| Dinosaurs roamed the earth aleady 200 million years ago, and
| died in the mass extinction 65 million years ago. 20 to 5
| million years ago was the Miocene, when life was pretty close
| to modern already. [2]
|
| It's really the nature of exponential growth that makes
| things seem instantaneous compared to celestial phenomena or
| evolution. Colonizing the galaxy, even with abysmally slow
| speeds, is possible, because of the magic of exponentials.
|
| (Certainly this has a lot of assumption, like that you can
| bootstrap, or that the probe survives the trip. Anyway,
| optimal probes would be a lot faster and bigger, and there
| would be more of them. This was just to tie in with something
| concrete that we know we can do, as Voyager 1 really is out
| there traveling at 15 km/s, as are Voyager 2, Pioneers and
| New Horizons probes.)
|
| 1: https://www.wolframalpha.com/input/?i=+30+light+years+%2F+
| vo...
|
| 2: https://en.wikipedia.org/wiki/Miocene
| wing-_-nuts wrote:
| We always assume that civilizations expand into space without
| consideration for benefit, but I don't think that will be the
| case, honestly.
|
| Should we want a colony on another planet? In another star
| system? Absolutely. It doesn't take much expansion for us to
| achieve the goal of having a 'redundant backup' for humanity.
|
| Beyond that, there _has_ to be some sort of economic
| incentive to drive it. Given there is little chance we can
| economically trade between planets, much less between star
| systems, I don 't think that incentive is there.
| tobyjsullivan wrote:
| Exactly this. I was thinking about this the other day and
| using the web as a metaphor (bear with me).
|
| It's easy to know where to go next when we only have one
| option to pursue (such as travelling to the next nearest
| planet or star). This is a lot like the early web when
| there were only a handful of interesting sites and
| discovering new cool sites was a goal in and of itself.
|
| Today, I think we intuitively understand that there's no
| longer any value in trying to visit every website on the
| internet. Most sites offer zero value or even net negative
| value. The entire problem space pivots to one of knowing
| which 0.00001% of websites are valuable to a given
| situation.
|
| When a civilization gains the ability to visit any
| planetary system, the problem shifts to one of filtering
| choices and information to minimize the amount of
| unnecessary travel or world-settling.
|
| I assume this is a well-known concept. I'd love to read
| more if anybody knows what it's called.
| brabel wrote:
| Absolutely agree. I think that once you've established your
| civilization over a few stars and planets your survival is
| pretty much guaranteed against astronomical destruction (if
| there's anything huge enough to destroy ALL the stars
| you've colonized, you probably can tell with billions of
| years in advance), the incentive changes and you now want
| to basically go on stealth mode to make sure you don't
| actually attract any nasty neighbour's attention, because
| that may be the only thing you can NOT see that may be
| dangerous.
|
| And notice that people from different star systems in the
| same civilization will very likely only have extremely rare
| direct encounters due to the brutally long distances
| involved... it's highly likely the civilization will split
| up into completely separate "star nations", with their own
| internal issues to keep them busy and at some point may
| lose interest even in communicating with other star
| systems... without any incentive at all to expand further
| as the species survival is guaranteed... curiosity wouldn't
| be strong enough, probably, because after getting to know
| several star systems, you may decide they are look more or
| less the same, and to find anything really interesting
| might take multi-million year journeys and no one would be
| able to embark on something like that just for curiosity.
| lrem wrote:
| > if there's anything huge enough to destroy ALL the
| stars you've colonized, you probably can tell with
| billions of years in advance
|
| I can't think of any phenomena that could come close to
| doing such a thing. But if there was one, why couldn't it
| be like gamma bursts?
| anomaloustho wrote:
| I've heard it said that if humanity simply maintains its
| growth pace, there should be enough human bodies to pile up
| into the entire solar system just by waiting X number of
| years.
| bluGill wrote:
| > if humanity simply maintains its growth pace
|
| But humanity is not doing that. The current trend is
| world population will peak at just over 9 billion in
| about 30 years. Trends can change, but that is the
| current one.
| jandrese wrote:
| Every growth curve is an S curve. Every time you see one
| of those studies where someone takes a system that is
| still in an early growth phase and projects it out to
| infinity at the current growth rate it is always
| nonsense.
| netjiro wrote:
| One benefit is reduced risk of extinction by the various
| nasty ways the grand cosmos might annihilate a local-only
| civilisation.
|
| Let's consider extinction mitigation as a luxury? I posit
| that sooner or later, as technology improves, the relative
| cost of such projects will go down to a point where some
| group of people think it is a good idea.
| wing-_-nuts wrote:
| Again, you don't have to expand to more than a couple of
| self sustaining planets in a couple of solar systems to
| establish a reasonable redundant backup for mankind.
|
| I don't think new discoveries suddenly change the physics
| of escaping gravity wells. I question whether
| interplanetary trade will ever move beyond intellectual
| property.
|
| Basically, colonization will have to be altruistically
| funded without any expectation of economic return. We've
| proven we have limited capacity for that.
| Loughla wrote:
| >We've proven we have limited capacity for that.
|
| Currently.
|
| In a system where resources are allocated not to cover
| the needs of all, but instead to ensure that the victor
| gets their spoils, this is true.
|
| But IF a civilization makes it to a point where self-
| sustaining planet settlement is even a real possibility,
| I think you just have to assume they are post-scarcity
| and post-currency. Economic return isn't really a thing,
| if everyone can get what they want whenever they want it.
|
| Therefore, any species with a natural propensity to
| exploration and curiosity as an individual is going to
| necessarily seek out new places as a whole. The
| individual will drive the societal, I guess is what I
| mean there. Because I want to see something new, and
| there is no scarcity of resources, society as a whole
| gets to see something new.
|
| >I question whether interplanetary trade will ever move
| beyond intellectual property.
|
| Honestly, I don't think so. Because, again, I'm of the
| firm belief that once a society is able to establish off-
| world colonies successfully, economics stops meaning
| anything at all, really.
| rsynnott wrote:
| > Because I want to see something new, and there is no
| scarcity of resources, society as a whole gets to see
| something new.
|
| You might _explore_. You're less likely to _colonise_.
| The only way you get the sort of geometric expansion
| people love to talk about is if there's a very strong
| imperative to colonise, and it's just not clear that it
| exists.
| deepsun wrote:
| > if you can produce energy that cheaply you can sustain a
| large population in comfort at home
|
| Don't see the reasoning here.
|
| For example, we currently can feed the whole Earth population
| "cheaply". But the wars didn't end. Same with cheap energy.
|
| E.g. we can try to install vast amounts of mirrors to direct
| Sun's light towards an accelerating ship. But that won't
| bring us here more comfort.
| kindle-dev wrote:
| Even without FTL travel, just having constant acceleration at
| 1g is enough to travel the width of the galaxy in 12 years
| ship-time: https://en.wikipedia.org/wiki/Space_travel_using_c
| onstant_ac....
| rsynnott wrote:
| That is a _huge_ 'just', tho. That's a lot of energy.
| jandrese wrote:
| Try plugging 12 years of 1G acceleration into the Rocket
| Equation.
|
| If reactionless drives remain science fiction this mode of
| travel is flat impossible. There literally isn't enough
| mass in the solar system.
| htrp wrote:
| Welcome to the delta V problem....
| Retric wrote:
| #1 has some huge assumptions built in. A civilization can
| travel a long distance without visiting every star system
| between it's origin and destination.
|
| The limitation could be doubling time not travel time. Sure
| double every 100,000 years or less and in 4 million years
| you've run out of stars in the Milky Way which is an eye blink
| on cosmic timescales. But, a civilization that's remote
| terraforming worlds that might greatly slow things down. How
| long does it take Cyanobacteria to create an oxygen atmosphere
| for example?
| AutumnCurtain wrote:
| I felt like I could have used a better articulation of their
| definition of "loud" and "quiet" aliens, unless these are well
| known terms in the domain terms and I am just unfamiliar...
| [deleted]
| mannykannot wrote:
| The abstracts of papers are intentionally terse, which
| usually means they are addressed to people already familiar
| with the field. The paper itself is often more readable
| (though by no means always!) and it is often worth taking a
| look at the introduction and conclusion, at least. Here, we
| have _' To a first approximation, there are two kinds of
| aliens: quiet and loud. Loud (or "expansive") aliens expand
| fast, last long, and make visible changes to their volumes.
| Quiet aliens fail to meet at least one of these criteria.'_
| tgv wrote:
| 1. People named "Wang" spread at a certain speed after coming
| into existence.
|
| 2. I don't know anybody named "Wang".
|
| 3. There are no people named "Wang" in the galaxy.
| [deleted]
| groby_b wrote:
| "If we assume that our knowledge is the pinnacle of knowledge, we
| are the first to reach it" is a bit tautological, no?
|
| You can apply a very similar reasoning to an isolated tribe stuck
| at, say, stone-age level on a remote island. With barely
| seaworthy canoes. They very likely have no idea we exist, and
| their assumption will be that if there were better canoes, and
| people had them, they would've made contact. So clearly, they
| must be among the first.
|
| I am continually amused by the gyrations we go through to avoid
| saying "we don't know".
|
| I mean, last I checked we couldn't even account for 85% of the
| matter in the universe that should exist according to the laws of
| physics as we know them. If we can't even find the vast majority
| of matter, why do we think we'd do better with civilizations?
| whyAstate wrote:
| What if aliens nearly exhausted their home planet resources and
| scaled back industrial life?
|
| Perhaps too many technical missteps, social unrest, meant they've
| linearly creeped along making no technological leaps, but still
| providing a decent life to each other, until so much time went
| by, they realized too late about the possibility of space travel?
|
| This is always feels like humans looking for our doppelgangers to
| sell a sensational concept.
| [deleted]
| [deleted]
| jefftk wrote:
| Full paper: https://arxiv.org/pdf/2102.01522.pdf
| est31 wrote:
| HTML version: https://www.arxiv-vanity.com/papers/2102.01522/
| matchagaucho wrote:
| > _Which seems bad news for SETI._
|
| SETI conceded many years ago that the evidence of a "Loud" alien
| species > a few Million years ago might be virtually undetectable
| today.
| RupertEisenhart wrote:
| For more background and related material, look at Hansons blog[0]
| or the dedicated website[1].
|
| [0]: https://www.overcomingbias.com/?s=aliens
|
| [1]: https://grabbyaliens.com/
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