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Obligatory talking points associated with the Fermi Paradox: - It takes a very short time in comparison to the age of the galaxy for a single self-replicating

Obligatory talking points associated with the Fermi Paradox: - It takes a very short time in comparison to the age of the galaxy for a single self-replicating probe to result in a descendant probe visit to every star. A few million years. This means that you cannot really argue plausibly that all civilizations fail to do this - it would take trivial effort for just one faction within just one advanced civilization to set this underway. It's quite clearly the case that we will do it when we can. - There is a proposal I recall reading that suggests all colonization/self-replicated expansion is patchy in a sort of fractal way. You're always going to get sparse frontiers and empty real estate. - The Great Filter. http://en.wikipedia.org/wiki/Great_Filter http://en.wikipedia.org/wiki/Great_Filter - The Simulation Argument (Bostrom variant). http://en.wikipedia.org/wiki/Simulation_hypothesis http://en.wikipedia.org/wiki/Simulation_hypothesis - The Drake Equation http://en.wikipedia.org/wiki/Drake_equation http://en.wikipedia.org/wiki/Drake_equation - Where are the macrostructures? We don't see Dyson spheres or other evident macroscale engineering. Everything we can see so far looks natural. This is more troubling than an absence of detectable communications. There are any number of ways we can think of for interstellar communication networks to exist and yet be undetectable by us at the moment, and then there are no doubt all the ways that we can't think of. - Agents responsible for the Fermi Paradox through suppression of nascent intelligence are a popular science fiction trope. First one to the top kills off the rest as they turn up. (Berzerkers, Wolves, etc). It makes for good plotting, but in reality this suffers from all the same issues as economic monopolies and monocultures - i.e. without some sustaining outside influence they are fragile and short-lived, prone to defection, being undercut, and out-innovated from a blind spot. So it's not plausible to suppose that we are randomly in a period of suppressive monopoly.

chongli 13y ago
>Where are the macrostructures? We don't see Dyson spheres or other evident macroscale engineering. Everything we can see so far looks natural. This is more troubling than an absence of detectable communications. Assuming a Dyson sphere was nearby, how would we detect it? What would it look like? If it's able to make use of most of a star's radiation output, wouldn't that make it very difficult to see? It wasn't until recently that we were able to detect black holes and I'd have to guess a Dyson sphere's star would be much less massive and energetic than that.
- Udo 13y ago
  Even a Dyson sphere can't just swallow the star's radiation. It makes use of a potential gradient, which means it would have to radiate away some energy on the outside. This would probably show up as, say, a brown dwarf. Still, if it's not in our direct neighborhood the chances of us discovering it are even lower.
  - abrichr 13y ago
    The Wikipedia article defines a Dyson sphere as a system of orbiting solar-power satellites meant to completely encompass a star and capture most or all of its energy output.
    - Udo 13y ago
      I think there is a misunderstanding here about what that means in practice. Thermodynamics still applies. Energy has to be harnessed across gradients. Even if they wanted to only collect visible light, they'd have to radiate the heat somewhere.
  - jl6 13y ago
    Unless the engineers are concerned about detection and choose somehow to radiate in only one narrow direction, pointed away from any nearby stars.
    - Udo 13y ago
      That's true, and stealth is an interesting proposition. However, there are probably easier methods of preventing detection, such as not building a giant structure in the first place. Also, even if they manage to radiate away most of their waste heat, they'd have to assume eventual detection by an advanced civilization. Sure, with exponential effort you can always get infinitesimally closer to being virtually undetectable, but is that really feasible? In the end, it's certainly not impossible that a civilization would go to extreme lengths in order to hide its enormous artificial structures. But the real issue is: why would all civilizations hide in this way? And if it turns out they do all have elaborate stealth tech in operation, that means there must be an incomprehensibly huge threat out there - which in itself might be the answer to why nobody is calling us up.
Udo 13y ago
Considering the vast time scales and the vastness of the galaxy, the most plausible explanation for me is still that we happen to live in a historical dark zone. But it's fun to speculate since any number or combination of events might be responsible for the absence of fellow civilizations. There is a Great Filter argument that tries to say that we're really, really, really special or that our civilization-ending event might still be in the future. Since we're speculating, I don't think the biological filter argument is very plausible. Historically, we have always been proven utterly wrong after presuppositions of specialness. On the other hand if the Filter is ahead of us, it would have to happen very soon - good candidates for this remain AI, nano tech, or plain apathy. But then again assuming these would be an issue for every advanced civilization seems a stretch. The simulation argument only makes a difference if the simulation is specifically targeted and limited to simulating us humans. If it's just a universe in a box, it wouldn't tip the scales either way. The Drake equation and its cousins are nice, but they contain a lot of unknowns. Still, it's a good tool that shows how easy it would be to have statistical fluctuations resulting in a dark epoch. I personally like the Agents of Suppression theory as well. It wouldn't even have to be another civilization suppressing everything directly - it could just as well be a completely automated armada of leftover killer robots. In my opinion it's one of the more plausible hostile alien invasion-stories as well: one day, we'll fulfill a set of unknown criteria and are simply tagged for extermination. But again, they would have to come our way pretty soon, like in the next 1000 years (which is not a lot of time). This would require a pangalactic drone network for observation and a fast local strike capability. Not completely unfeasible, but not exactly obvious either. The absence of large-scale artifacts is also interesting, but we have to ask ourselves if we could even detect, say, a ring world or a Dyson sphere if it was in our direct neighborhood (and chances are, it wouldn't be that close). Also, intelligent civilizations would not necessarily produce them. However it would be enough if a few did build huge structures. Again, I don't think we're advanced enough to detect them (or their absence) with any confidence.
- sampo 13y ago
  > the most plausible explanation for me is still that we happen to live in a historical dark zone. I am no expert, but I remember reading somewhere that our Sun is among the first generation of solar systems that were born with enough heavy elements to make life based on carbon, oxygen, nitrogen, occasional iron etc. possible. That there first needs to be some generations of starts going nova so that the stars have generated the heavier elements, and then the supernova explosions have to spread these around to that then the new interstellar clouds have enough of these element when they collapse to next generation stars and solar systems.
olalonde 13y ago
I think it is quite likely that after discovering mind uploading technology (assuming such a thing is possible), advanced civilizations lose interest in the "boring" and "dangerous" space-time world. This idea would probably fall into the "Simulation Argument" you mentioned. But in sll honesty, I don't think humanity will ever have a satisfying answer to Fermi's paradox.
- jerf 13y ago
  Without some sort of technology that renders them truly immune to the "dangerous" space-time world, they won't be able to ignore it, because if their sun burps they all die if their simulators get destroyed. Even if they "all" happily charge into simulated bliss, a residual caretaking system should be visible as it performs the necessary cosmic-scale engineering to ensure that the simulated ones don't get wiped out by a cosmological crisis, such as a supernova. Further, any such society will still end up wanting more and more energy, so we ought to be seeing Dyson shells or something pop up, in the continuing absence of any apparently way of converting mass directly into energy. We don't see any of these things. And the amount of "space" left in physics for some sort of true escape hatch that might let us escape fully into an impregnable universe of our own devising or something keeps going down and down. I consider the lack of cosmic-scale engineering to be a much bigger problem than mere inability to detect signals. A lot of it isn't even that "hard" per se, because what's impossible on the year or century scale becomes feasible with only very realistic projections of what self-replicating technology can do if you can put in millions of years of continuous effort. And a lot of this stuff would both be visible, and essentially necessary; if life is so inevitable and intelligent civilizations so likely, quite a few of them will find themselves dangerously close to an incipient supernova on an uncomfortable time frame, and they ought to be doing things about that. Very visible things. It's just too perfectly quiet out there.
Tloewald 13y ago
The ground assumption in all of this is that we have some comprehension of the technological end-game / plateau. I.e. that a civilization far more advanced than our own will still care about solar energy and EMR communications. Who is going to build a Dyson Sphere for fun? We could be totally wrong about this. We probably are. The other possibility is that there's not much more technology for us. Can we build self-replicating probes that can operate, without maintenance, for thousands of years? No we can't. So we have this wacky set of assumptions -- that alien civilizations will be more advanced than us in certain peculiar ways (able to build self-replicating probes and/or Dyson spheres) but not in others (having the primitive needs and side-effects that we do). This is a tiny corner of a very large set of possibilities. Maybe the aliens simply build new Universes to order and leave their birth universe behind because it's (a) less hospitable than their new "air conditioned" universe, and (b) it's unethical or boring or pointless to colonize a universe full of new potential civilizations. Folks need to read some less mainstream SF. I like Clifford Simak's "City" where the vast majority of the human race emigrates to Jupiter to live as hunter-gatherers (because Jovian life is so much more pleasant than human life) leaving Earth to the dogs, robots, and ants.
- exratione 13y ago
  To be clear, "self-replicating probe" includes all technologies that can transport, at a minimum, human genetic material, a record of all human science and technology to date, and creche-building technology to a distant star. So a few grams or kilograms of bootstrap molecular nanotechnology, computing material, shielding, some form of reaction engine, fuel for deceleration, and fired by the hundred from a solar-system-wide array of magnetic accelerators or accelerated by lasers. More likely the human genetic material will be absent in favor of emulated human minds. Or think about actual humans, something large that we'd recognize as a starship, and a vast amount of antimatter. Much more spectacular, and much less likely, because of the amounts of energy involved in getting the job done - and all that just to ship things that could be build on site. The point being that even if you say that we'll never build self-replicating technology (which is essentially the same as being a vitalist) then given the time scales involved - if every step in the probe network takes 1,000 to 10,000 years of resting time to build a complete organic human civilization before kicking off the next series of probes - it still requires a short time span to visit all stars in the galaxy in comparison to the age of the galaxy.
ChuckMcM 13y ago
This is a good summary. One of the missing pieces is we don't know what the minimum set of combinational factors are to create "advanced" civilization. The scare quotes for advanced here are that two incompatible definitions for civilization quality compete for the nominative "advanced." In the current context advanced means we've developed machines that carry us into space, we can create habitats to survive in even when our surrounding habitat is inhospitable and we leverage natural resources to create excess food. An alternative context for "advanced" is that your civilization exists in balance with the other processes on the planet, you don't create anything that that wouldn't be created by natural processes inherent in the system, and your resource utilization is at a rate that does not exceed its replenishment rate. Further you explicitly do not use any resource that is not naturally replenished. In the context of that dichotomy, the question might be "Why didn't the Dinosaurs develop space flight?" They lived on the planet for millions of years before we got here, there is evidence that their cognitive capacity was at least as large as ours, and some species had the ability to manipulate matter at least as well as our paleolithic ancestors did. So why didn't they build giant Dinosaur cities, grow Dinosaur food, and build institutions of higher learning? Depending on your timeline we went from struggling ape to SpaceX in 3 - 5 million years. They had 165 million years to figure it out. Why were they even on the planet when the asteroid hit, and/or why didn't they do something about it before it hit? Using Dinosaur lasers or something. Depending on how you count we've gone through 5 to 7 nearly total extinctions on this planet. What made this last one special? What is the key set of things that have to be true in order for life to go from being intelligent to manipulating everything around it in its environment to serve the will of that intelligence? They are complex questions. Great fun to contemplate on camping trips, while under the influence, and when you've run out of other 'safe' conversational starters.
- VLM 13y ago
  One of the semi serious answers is you need a peculiar and somewhat unusual arrangement of land and sea to create a long series of oscillating ice ages every ten thousand years or so (to one sig fig), which is just the right wavelength to very strongly evolve intelligence and civilization. Without that intense adaptation pressure you don't get growth. With enough of it, you get us.
sage_joch 13y ago
Where are the macrostructures? We don't see Dyson spheres or other evident macroscale engineering. This might be a stupid question, but could the Red Square Nebula be considered a candidate? http://en.wikipedia.org/wiki/Red_Square_Nebula http://en.wikipedia.org/wiki/Red_Square_Nebula
- PBxdId7wFr 13y ago
  It's probably just in need of better imaging, like that old face of Mars from the 70s. Regards,
- Dn_Ab 13y ago
  I can't say but whenever I hear about something that 'defies' theory [n] I like to take a moment and. Imagine that the anomaly in question was constructed by unimaginably developed beings. Of plasma, computronium and other unmet exotic concepts. Powered by rainbows of gamma radiation from stars coerced into the bellies of super-massive black holes. Then I tidily put away the thought because I know it is not even falsifiable, I don't bother assigning probabilities like unlikely. But the short moment (following such news) of delight at contemplating exotic entities so foreign, that words like conscious and alive are inapplicable is a healthy pastime I much enjoy. [1] http://news.nationalgeographic.com/news/2013/01/130111-quasar-biggest-thing-universe-science-space-evolution/ http://news.nationalgeographic.com/news/2013/01/130111-quasa...
- anonymous 13y ago
  Well, it is probably natural. But if I was tasked with building a nebula-sized art project, that's what I would do. Though, I'd also put three planes intersecting the conical surface and showing off the three different conical intersections, then inscribe their equations on a planet orbiting the star at the centre.
DavidPlumpton 13y ago
Maybe interstellar travel is just really hard even with technology far beyond our own.
gridmaths 13y ago
Is it possible nearly all advanced species have gone to great lengths to hide their existence ? The more advanced, the better at hiding? Perhaps gravity is the only radiation they cant hide, so all we could detect of them is 'dark matter'?

chongli 13y ago

>Where are the macrostructures? We don't see Dyson spheres or other evident macroscale engineering. Everything we can see so far looks natural. This is more troubling than an absence of detectable communications. Assuming a Dyson sphere was nearby, how would we detect it? What would it look like? If it's able to make use of most of a star's radiation output, wouldn't that make it very difficult to see? It wasn't until recently that we were able to detect black holes and I'd have to guess a Dyson sphere's star would be much less massive and energetic than that.

Udo 13y ago
Even a Dyson sphere can't just swallow the star's radiation. It makes use of a potential gradient, which means it would have to radiate away some energy on the outside. This would probably show up as, say, a brown dwarf. Still, if it's not in our direct neighborhood the chances of us discovering it are even lower.
- abrichr 13y ago
  The Wikipedia article defines a Dyson sphere as a system of orbiting solar-power satellites meant to completely encompass a star and capture most or all of its energy output.
  - Udo 13y ago
    I think there is a misunderstanding here about what that means in practice. Thermodynamics still applies. Energy has to be harnessed across gradients. Even if they wanted to only collect visible light, they'd have to radiate the heat somewhere.
- jl6 13y ago
  Unless the engineers are concerned about detection and choose somehow to radiate in only one narrow direction, pointed away from any nearby stars.
  - Udo 13y ago
    That's true, and stealth is an interesting proposition. However, there are probably easier methods of preventing detection, such as not building a giant structure in the first place. Also, even if they manage to radiate away most of their waste heat, they'd have to assume eventual detection by an advanced civilization. Sure, with exponential effort you can always get infinitesimally closer to being virtually undetectable, but is that really feasible? In the end, it's certainly not impossible that a civilization would go to extreme lengths in order to hide its enormous artificial structures. But the real issue is: why would all civilizations hide in this way? And if it turns out they do all have elaborate stealth tech in operation, that means there must be an incomprehensibly huge threat out there - which in itself might be the answer to why nobody is calling us up.

Udo 13y ago

Considering the vast time scales and the vastness of the galaxy, the most plausible explanation for me is still that we happen to live in a historical dark zone. But it's fun to speculate since any number or combination of events might be responsible for the absence of fellow civilizations. There is a Great Filter argument that tries to say that we're really, really, really special or that our civilization-ending event might still be in the future. Since we're speculating, I don't think the biological filter argument is very plausible. Historically, we have always been proven utterly wrong after presuppositions of specialness. On the other hand if the Filter is ahead of us, it would have to happen very soon - good candidates for this remain AI, nano tech, or plain apathy. But then again assuming these would be an issue for every advanced civilization seems a stretch. The simulation argument only makes a difference if the simulation is specifically targeted and limited to simulating us humans. If it's just a universe in a box, it wouldn't tip the scales either way. The Drake equation and its cousins are nice, but they contain a lot of unknowns. Still, it's a good tool that shows how easy it would be to have statistical fluctuations resulting in a dark epoch. I personally like the Agents of Suppression theory as well. It wouldn't even have to be another civilization suppressing everything directly - it could just as well be a completely automated armada of leftover killer robots. In my opinion it's one of the more plausible hostile alien invasion-stories as well: one day, we'll fulfill a set of unknown criteria and are simply tagged for extermination. But again, they would have to come our way pretty soon, like in the next 1000 years (which is not a lot of time). This would require a pangalactic drone network for observation and a fast local strike capability. Not completely unfeasible, but not exactly obvious either. The absence of large-scale artifacts is also interesting, but we have to ask ourselves if we could even detect, say, a ring world or a Dyson sphere if it was in our direct neighborhood (and chances are, it wouldn't be that close). Also, intelligent civilizations would not necessarily produce them. However it would be enough if a few did build huge structures. Again, I don't think we're advanced enough to detect them (or their absence) with any confidence.

sampo 13y ago
> the most plausible explanation for me is still that we happen to live in a historical dark zone. I am no expert, but I remember reading somewhere that our Sun is among the first generation of solar systems that were born with enough heavy elements to make life based on carbon, oxygen, nitrogen, occasional iron etc. possible. That there first needs to be some generations of starts going nova so that the stars have generated the heavier elements, and then the supernova explosions have to spread these around to that then the new interstellar clouds have enough of these element when they collapse to next generation stars and solar systems.

olalonde 13y ago

I think it is quite likely that after discovering mind uploading technology (assuming such a thing is possible), advanced civilizations lose interest in the "boring" and "dangerous" space-time world. This idea would probably fall into the "Simulation Argument" you mentioned. But in sll honesty, I don't think humanity will ever have a satisfying answer to Fermi's paradox.

jerf 13y ago
Without some sort of technology that renders them truly immune to the "dangerous" space-time world, they won't be able to ignore it, because if their sun burps they all die if their simulators get destroyed. Even if they "all" happily charge into simulated bliss, a residual caretaking system should be visible as it performs the necessary cosmic-scale engineering to ensure that the simulated ones don't get wiped out by a cosmological crisis, such as a supernova. Further, any such society will still end up wanting more and more energy, so we ought to be seeing Dyson shells or something pop up, in the continuing absence of any apparently way of converting mass directly into energy. We don't see any of these things. And the amount of "space" left in physics for some sort of true escape hatch that might let us escape fully into an impregnable universe of our own devising or something keeps going down and down. I consider the lack of cosmic-scale engineering to be a much bigger problem than mere inability to detect signals. A lot of it isn't even that "hard" per se, because what's impossible on the year or century scale becomes feasible with only very realistic projections of what self-replicating technology can do if you can put in millions of years of continuous effort. And a lot of this stuff would both be visible, and essentially necessary; if life is so inevitable and intelligent civilizations so likely, quite a few of them will find themselves dangerously close to an incipient supernova on an uncomfortable time frame, and they ought to be doing things about that. Very visible things. It's just too perfectly quiet out there.

Tloewald 13y ago

The ground assumption in all of this is that we have some comprehension of the technological end-game / plateau. I.e. that a civilization far more advanced than our own will still care about solar energy and EMR communications. Who is going to build a Dyson Sphere for fun? We could be totally wrong about this. We probably are. The other possibility is that there's not much more technology for us. Can we build self-replicating probes that can operate, without maintenance, for thousands of years? No we can't. So we have this wacky set of assumptions -- that alien civilizations will be more advanced than us in certain peculiar ways (able to build self-replicating probes and/or Dyson spheres) but not in others (having the primitive needs and side-effects that we do). This is a tiny corner of a very large set of possibilities. Maybe the aliens simply build new Universes to order and leave their birth universe behind because it's (a) less hospitable than their new "air conditioned" universe, and (b) it's unethical or boring or pointless to colonize a universe full of new potential civilizations. Folks need to read some less mainstream SF. I like Clifford Simak's "City" where the vast majority of the human race emigrates to Jupiter to live as hunter-gatherers (because Jovian life is so much more pleasant than human life) leaving Earth to the dogs, robots, and ants.

exratione 13y ago
To be clear, "self-replicating probe" includes all technologies that can transport, at a minimum, human genetic material, a record of all human science and technology to date, and creche-building technology to a distant star. So a few grams or kilograms of bootstrap molecular nanotechnology, computing material, shielding, some form of reaction engine, fuel for deceleration, and fired by the hundred from a solar-system-wide array of magnetic accelerators or accelerated by lasers. More likely the human genetic material will be absent in favor of emulated human minds. Or think about actual humans, something large that we'd recognize as a starship, and a vast amount of antimatter. Much more spectacular, and much less likely, because of the amounts of energy involved in getting the job done - and all that just to ship things that could be build on site. The point being that even if you say that we'll never build self-replicating technology (which is essentially the same as being a vitalist) then given the time scales involved - if every step in the probe network takes 1,000 to 10,000 years of resting time to build a complete organic human civilization before kicking off the next series of probes - it still requires a short time span to visit all stars in the galaxy in comparison to the age of the galaxy.

ChuckMcM 13y ago

This is a good summary. One of the missing pieces is we don't know what the minimum set of combinational factors are to create "advanced" civilization. The scare quotes for advanced here are that two incompatible definitions for civilization quality compete for the nominative "advanced." In the current context advanced means we've developed machines that carry us into space, we can create habitats to survive in even when our surrounding habitat is inhospitable and we leverage natural resources to create excess food. An alternative context for "advanced" is that your civilization exists in balance with the other processes on the planet, you don't create anything that that wouldn't be created by natural processes inherent in the system, and your resource utilization is at a rate that does not exceed its replenishment rate. Further you explicitly do not use any resource that is not naturally replenished. In the context of that dichotomy, the question might be "Why didn't the Dinosaurs develop space flight?" They lived on the planet for millions of years before we got here, there is evidence that their cognitive capacity was at least as large as ours, and some species had the ability to manipulate matter at least as well as our paleolithic ancestors did. So why didn't they build giant Dinosaur cities, grow Dinosaur food, and build institutions of higher learning? Depending on your timeline we went from struggling ape to SpaceX in 3 - 5 million years. They had 165 million years to figure it out. Why were they even on the planet when the asteroid hit, and/or why didn't they do something about it before it hit? Using Dinosaur lasers or something. Depending on how you count we've gone through 5 to 7 nearly total extinctions on this planet. What made this last one special? What is the key set of things that have to be true in order for life to go from being intelligent to manipulating everything around it in its environment to serve the will of that intelligence? They are complex questions. Great fun to contemplate on camping trips, while under the influence, and when you've run out of other 'safe' conversational starters.

VLM 13y ago
One of the semi serious answers is you need a peculiar and somewhat unusual arrangement of land and sea to create a long series of oscillating ice ages every ten thousand years or so (to one sig fig), which is just the right wavelength to very strongly evolve intelligence and civilization. Without that intense adaptation pressure you don't get growth. With enough of it, you get us.

sage_joch 13y ago

Where are the macrostructures? We don't see Dyson spheres or other evident macroscale engineering. This might be a stupid question, but could the Red Square Nebula be considered a candidate? http://en.wikipedia.org/wiki/Red_Square_Nebula http://en.wikipedia.org/wiki/Red_Square_Nebula

PBxdId7wFr 13y ago
It's probably just in need of better imaging, like that old face of Mars from the 70s. Regards,
Dn_Ab 13y ago
I can't say but whenever I hear about something that 'defies' theory [n] I like to take a moment and. Imagine that the anomaly in question was constructed by unimaginably developed beings. Of plasma, computronium and other unmet exotic concepts. Powered by rainbows of gamma radiation from stars coerced into the bellies of super-massive black holes. Then I tidily put away the thought because I know it is not even falsifiable, I don't bother assigning probabilities like unlikely. But the short moment (following such news) of delight at contemplating exotic entities so foreign, that words like conscious and alive are inapplicable is a healthy pastime I much enjoy. [1] http://news.nationalgeographic.com/news/2013/01/130111-quasar-biggest-thing-universe-science-space-evolution/ http://news.nationalgeographic.com/news/2013/01/130111-quasa...
anonymous 13y ago
Well, it is probably natural. But if I was tasked with building a nebula-sized art project, that's what I would do. Though, I'd also put three planes intersecting the conical surface and showing off the three different conical intersections, then inscribe their equations on a planet orbiting the star at the centre.

DavidPlumpton 13y ago

Maybe interstellar travel is just really hard even with technology far beyond our own.

gridmaths 13y ago

Is it possible nearly all advanced species have gone to great lengths to hide their existence ? The more advanced, the better at hiding? Perhaps gravity is the only radiation they cant hide, so all we could detect of them is 'dark matter'?