The ones closer to us, if they exist, will likely be alive and the ones coming from far away will be more likely to be dead when they arrive.Space travel is never trivial, unless you go into science fictional levels of technology where you snap your fingers and a spaceship appears and you can travel close to the speed of light. But I suppose we're talking about reasonable, "known to us" means of propulsion as well as manufacturing and outfitting (i.e. no magical force fields to contain hull breaches). The longer they have to travel (just imagine sitting on top of each other for 1000 years, classes/factions are going to form, in-ship wars may be inevitable) the more likely it is that some technical failure, sabotage, uprising or other stuff happens that damages their ship and renders it uninhabitable.So, either a long distance species coming to us is extremely peaceful (towards each other and probably towards outsiders) or dead.
The issue is not about us physically meeting them. It’s about us SEEING (or rather NOT seeing) evidence of their civilizations in their home galaxies. The older they are the more visible an effect these “grabby aliens” should have on their stellar neighbourhood. To explain this lack of detection, the Grabby Alien hypothesis says that those old enough to have visibly changed their stellar environments HAVE to be far enough away that the light of their civilization has not had time to reach us yet.So a “mega structure / stellar engineering capable” civilization could have arisen 500M years ago in a galaxy 1B light years away, but it is not allowed to have arisen in the next door Andromeda galaxy more than 2.5 million years ago. Or in the Milky Way itself more than ~100K years ago. Else we would see evidence of it.So the theory requires that the older a civilization is, the farther away from Earth it has to be. That’s a weird, rather Earth-centric condition that has no logical or natural reason for existing, other than to make the theory work.
Our recent analysis suggests that they appear at random stars roughly once per million galaxies, and then expand at roughly half the speed of light. Right now, they have filled roughly half of the universe, and if we join them we’ll meet them in roughly a billion years. There may be far more quiet than grabby alien civs out there, but those don’t usually do much or last long, and even the ruins of the nearest are quite far away.
Quote from: M.E.T. on 11/30/2022 03:13 amThe issue is not about us physically meeting them. It’s about us SEEING (or rather NOT seeing) evidence of their civilizations in their home galaxies. The older they are the more visible an effect these “grabby aliens” should have on their stellar neighbourhood. To explain this lack of detection, the Grabby Alien hypothesis says that those old enough to have visibly changed their stellar environments HAVE to be far enough away that the light of their civilization has not had time to reach us yet.So a “mega structure / stellar engineering capable” civilization could have arisen 500M years ago in a galaxy 1B light years away, but it is not allowed to have arisen in the next door Andromeda galaxy more than 2.5 million years ago. Or in the Milky Way itself more than ~100K years ago. Else we would see evidence of it.So the theory requires that the older a civilization is, the farther away from Earth it has to be. That’s a weird, rather Earth-centric condition that has no logical or natural reason for existing, other than to make the theory work.From what I gather about the grabby aliens hypothesis, it is specifically designed to address the question of why humans have appeared so early in the universe's existence, 13.8 billion years in, when the average star in the universe will last ~5 trillion years and it is vastly more likely for advanced life to appear later rather than sooner by the hard-steps power law model of the origin of advanced life. It states that if we assume that human civilization is not special in appearing so early (Copernican principle and all), then there must be something that prevents civilizations like ours from appearing and observing the universe like we do in those trillions of years of distant future; that "something" is grabby aliens, which drastically change their stellar environments and prevent the emergence of indigenous alien civilizations within their sphere of influence.Because we don't observe the kind of obvious stellar engineering activity that defines "grabby aliens", the appearance rate of these types of alien civilizations is highly constrained. Robin Hanson, who proposed and wrote the mathematical model behind this hypothesis, states the following here:QuoteOur recent analysis suggests that they appear at random stars roughly once per million galaxies, and then expand at roughly half the speed of light. Right now, they have filled roughly half of the universe, and if we join them we’ll meet them in roughly a billion years. There may be far more quiet than grabby alien civs out there, but those don’t usually do much or last long, and even the ruins of the nearest are quite far away.Those are the median values that his model spits out if we assume grabby civilizations both exist and haven't appeared in our light cone yet. So it's not that "the older a civilization is, the farther away from Earth it has to be"; it's that grabby aliens in particular are so rare and expand so fast that it isn't unusual that we don't see them yet (even then, Hanson predicts that over half the universe can currently see obvious alien activity in their night skies; we're just outside those light cones at the moment). Basically, we'll encounter the nearest one in about a billion years, and in under ten billion years every star in the observable universe will be within a grabby civilization. Thus, we observe ourselves appearing near the beginning of the universe's history because civilizations like ours can only appear near the beginning; Copernican principle preserved.
Quote from: Yiosie on 11/30/2022 04:39 amQuote from: M.E.T. on 11/30/2022 03:13 amThe issue is not about us physically meeting them. It’s about us SEEING (or rather NOT seeing) evidence of their civilizations in their home galaxies. The older they are the more visible an effect these “grabby aliens” should have on their stellar neighbourhood. To explain this lack of detection, the Grabby Alien hypothesis says that those old enough to have visibly changed their stellar environments HAVE to be far enough away that the light of their civilization has not had time to reach us yet.So a “mega structure / stellar engineering capable” civilization could have arisen 500M years ago in a galaxy 1B light years away, but it is not allowed to have arisen in the next door Andromeda galaxy more than 2.5 million years ago. Or in the Milky Way itself more than ~100K years ago. Else we would see evidence of it.So the theory requires that the older a civilization is, the farther away from Earth it has to be. That’s a weird, rather Earth-centric condition that has no logical or natural reason for existing, other than to make the theory work.From what I gather about the grabby aliens hypothesis, it is specifically designed to address the question of why humans have appeared so early in the universe's existence, 13.8 billion years in, when the average star in the universe will last ~5 trillion years and it is vastly more likely for advanced life to appear later rather than sooner by the hard-steps power law model of the origin of advanced life. It states that if we assume that human civilization is not special in appearing so early (Copernican principle and all), then there must be something that prevents civilizations like ours from appearing and observing the universe like we do in those trillions of years of distant future; that "something" is grabby aliens, which drastically change their stellar environments and prevent the emergence of indigenous alien civilizations within their sphere of influence.Because we don't observe the kind of obvious stellar engineering activity that defines "grabby aliens", the appearance rate of these types of alien civilizations is highly constrained. Robin Hanson, who proposed and wrote the mathematical model behind this hypothesis, states the following here:QuoteOur recent analysis suggests that they appear at random stars roughly once per million galaxies, and then expand at roughly half the speed of light. Right now, they have filled roughly half of the universe, and if we join them we’ll meet them in roughly a billion years. There may be far more quiet than grabby alien civs out there, but those don’t usually do much or last long, and even the ruins of the nearest are quite far away.Those are the median values that his model spits out if we assume grabby civilizations both exist and haven't appeared in our light cone yet. So it's not that "the older a civilization is, the farther away from Earth it has to be"; it's that grabby aliens in particular are so rare and expand so fast that it isn't unusual that we don't see them yet (even then, Hanson predicts that over half the universe can currently see obvious alien activity in their night skies; we're just outside those light cones at the moment). Basically, we'll encounter the nearest one in about a billion years, and in under ten billion years every star in the observable universe will be within a grabby civilization. Thus, we observe ourselves appearing near the beginning of the universe's history because civilizations like ours can only appear near the beginning; Copernican principle preserved.All of that still means that billion year old civilizations have to be more than a billion light years away, while 100 million year old civilizations only need to be 100 million light years away. The inverse would mean that the billion year old civilization would have been visible to us for the last 900 million years or so.So yes, it does mean that older civilizations have to be farther away to make the model work.
Quote from: Slothman on 11/27/2022 04:25 pm…..snip…So, either a long distance species coming to us is extremely peaceful (towards each other and probably towards outsiders) or dead.Agree with that assessment, which incidentally simply echoes 'the meek shall inherit...'.One should also adjust for the sheer improbability of technically intelligent life, with much less than 10,000 years of existence in the at least 1 billion years of life on earth.
…..snip…So, either a long distance species coming to us is extremely peaceful (towards each other and probably towards outsiders) or dead.
I also wonder if seeing signs of highly advanced aliens is overstated. It assumes that as aliens advance, their artifacts get larger and more visible. What if it's the opposite? We see some of that right here on Earth. Compare the pile of 19th-century explosives it would have taken to completely flatten London and its environs in Queen Victoria's time with a staged thermonuclear weapon that could so the same today to the even larger London. Or compare the size and contents of the RMS Titanic's engine room, all to produce 38 MW to the Raptor 2 which fits on a forklift pallet and produces multiple GW. Or a 1950's 4-story SAGE blockhouse to a modern truck-mounted air-defense control center.As tech gets better, it gets smaller. Modern computer chips have more transistors than our brains have neurons. Nano machinery is so small that it's invisible. A truly advanced alien may be microscopic, powered by cosmic radiation and manipulating space-time directly with some kind of quantum effectors. They may move have flooded their local space with uncountable numbers of these tiny bodies and be moving their consciousnesses between them at the speed of light. If there are enough of these tiny but highly absorptive creatures out there, we may only "see" them through their net gravitational effects. They could be the explanation for dark matter.Even if that's not the case, if advanced aliens have moved their tech to the quantum scales, they could be all over the space that we see but still be invisible to us. We could be the primitives standing under the cell towers looking for the giant drums that the civilized folks signal with and wondering where they all are.
We could be the primitives standing under the cell towers looking for the giant drums that the civilized folks signal with and wondering where they all are.
*snip* The answer is simple: pollution, changes in chemistry in stars, odd IR signatures. We don't so far as I know, see any of these so far *snip*Life, of course, is everywhere - but it is highly evolved, perfectly adapted, slime.
Quote from: M.E.T. on 11/30/2022 03:13 amThe issue is not about us physically meeting them. It’s about us SEEING (or rather NOT seeing) evidence of their civilizations in their home galaxies. The older they are the more visible an effect these “grabby aliens” should have on their stellar neighbourhood. To explain this lack of detection, the Grabby Alien hypothesis says that those old enough to have visibly changed their stellar environments HAVE to be far enough away that the light of their civilization has not had time to reach us yet.So a “mega structure / stellar engineering capable” civilization could have arisen 500M years ago in a galaxy 1B light years away, but it is not allowed to have arisen in the next door Andromeda galaxy more than 2.5 million years ago. Or in the Milky Way itself more than ~100K years ago. Else we would see evidence of it.So the theory requires that the older a civilization is, the farther away from Earth it has to be. That’s a weird, rather Earth-centric condition that has no logical or natural reason for existing, other than to make the theory work.But the reason why the grabbies have to be farther away, is because if they weren't, then they'd likely have already grabbed us by now. The older they are, the grabbier they can be, since their engineering capabilities only grow with time, and their Von Neumann swarms have more time to grow in size and voraciousness (provided their own swarms don't swarm back at them)Why is it that "the simpler alternative is that they’re just not there in the first place" ?? Why is that simpler?Simpler that they're not there? Or simpler that they're just not grabby?
Quote from: sanman on 12/01/2022 04:17 amQuote from: M.E.T. on 11/30/2022 03:13 amThe issue is not about us physically meeting them. It’s about us SEEING (or rather NOT seeing) evidence of their civilizations in their home galaxies. The older they are the more visible an effect these “grabby aliens” should have on their stellar neighbourhood. To explain this lack of detection, the Grabby Alien hypothesis says that those old enough to have visibly changed their stellar environments HAVE to be far enough away that the light of their civilization has not had time to reach us yet.So a “mega structure / stellar engineering capable” civilization could have arisen 500M years ago in a galaxy 1B light years away, but it is not allowed to have arisen in the next door Andromeda galaxy more than 2.5 million years ago. Or in the Milky Way itself more than ~100K years ago. Else we would see evidence of it.So the theory requires that the older a civilization is, the farther away from Earth it has to be. That’s a weird, rather Earth-centric condition that has no logical or natural reason for existing, other than to make the theory work.But the reason why the grabbies have to be farther away, is because if they weren't, then they'd likely have already grabbed us by now. The older they are, the grabbier they can be, since their engineering capabilities only grow with time, and their Von Neumann swarms have more time to grow in size and voraciousness (provided their own swarms don't swarm back at them)Why is it that "the simpler alternative is that they’re just not there in the first place" ?? Why is that simpler?Simpler that they're not there? Or simpler that they're just not grabby?That’s a bit like arguing the reason the boogeyman has to be on Easter Island rather in New York is because if he was in New York he would have attacked us by now.EDITIf you don’t see any aliens, surely it is simpler to argue they are not there (until evidence proves otherwise), than to contrive an answer where they HAVE to be there, but they all just happen to be at a distance where their age does not allow their light to have reached us yet. There could be multiple 5 billion year old civilizations, but according to this theory they just happen to all be more than 5 billion light years away. When in reality their distribution should be random, as the Milky Way or Andromeda is just as old as galaxies 5 or 10 billion light years away.
Quote from: M.E.T. on 12/01/2022 07:56 amQuote from: sanman on 12/01/2022 04:17 amQuote from: M.E.T. on 11/30/2022 03:13 amThe issue is not about us physically meeting them. It’s about us SEEING (or rather NOT seeing) evidence of their civilizations in their home galaxies. The older they are the more visible an effect these “grabby aliens” should have on their stellar neighbourhood. To explain this lack of detection, the Grabby Alien hypothesis says that those old enough to have visibly changed their stellar environments HAVE to be far enough away that the light of their civilization has not had time to reach us yet.So a “mega structure / stellar engineering capable” civilization could have arisen 500M years ago in a galaxy 1B light years away, but it is not allowed to have arisen in the next door Andromeda galaxy more than 2.5 million years ago. Or in the Milky Way itself more than ~100K years ago. Else we would see evidence of it.So the theory requires that the older a civilization is, the farther away from Earth it has to be. That’s a weird, rather Earth-centric condition that has no logical or natural reason for existing, other than to make the theory work.But the reason why the grabbies have to be farther away, is because if they weren't, then they'd likely have already grabbed us by now. The older they are, the grabbier they can be, since their engineering capabilities only grow with time, and their Von Neumann swarms have more time to grow in size and voraciousness (provided their own swarms don't swarm back at them)Why is it that "the simpler alternative is that they’re just not there in the first place" ?? Why is that simpler?Simpler that they're not there? Or simpler that they're just not grabby?That’s a bit like arguing the reason the boogeyman has to be on Easter Island rather in New York is because if he was in New York he would have attacked us by now.EDITIf you don’t see any aliens, surely it is simpler to argue they are not there (until evidence proves otherwise), than to contrive an answer where they HAVE to be there, but they all just happen to be at a distance where their age does not allow their light to have reached us yet. There could be multiple 5 billion year old civilizations, but according to this theory they just happen to all be more than 5 billion light years away. When in reality their distribution should be random, as the Milky Way or Andromeda is just as old as galaxies 5 or 10 billion light years away.There's a video on YouTube from one of the co-authors of the paper proposing the grabby aliens hypothesis that shows a 3D simulation of a median scenario in their model:The first grabby alien civilizations only appear about 6 billions years after the Big Bang due to the lack of heavy elements in Population III and II stars formed in the early universe. After 13.8 billion years, the majority of the observable universe is within a grabby alien civilization, but large gaps still exist where observers would see no obvious sign of aliens in their observable universes. To your point about multiple 5 billion year old civilizations, this particular sim shows only about 8-10 existing grabby alien civs in the observable universe 5 billion years ago; if evenly distributed, their origin points would be separated by over 5 billion light years on average today, and when randomly distributed there would be smaller and large gaps. "Older civilization far, newer civilization closer" is therefore unsurprising, given how incredibly rare grabby aliens are (only 87 appear in total for this particular simulation over the 20 billion years it takes for the observable universe to be full).The grabby aliens model doesn't "contrive an answer where they HAVE to be there", it hypothesizes the existence of grabby aliens (defined as civilizations that expand quickly and radically modify stars and galaxies for their use) specifically and explicitly to explain why humans have appeared very early in the universe's history without rejecting the Copernican principle: it proposes that we aren't special, and have in fact appeared close to the end of the time in the universe when we could have possibly spawned before the universe is filled. The model then constrains the appearance rate and expansion speeds of these grabby aliens due to the fact that we don't currently observe them.Of course, everything here assumes that we are not, in fact, extremely special or unique in the timing or presence of our civilization. That we are not alone, and that we have not appeared early due to luck.
Statistical we wouldn't be first or last. There are trillions of planets out there. Life on earth has existed for few 100million years and we've gone from ape to spacefaring in 100,000years.
Quote from: Yiosie on 12/01/2022 09:54 amQuote from: M.E.T. on 12/01/2022 07:56 amQuote from: sanman on 12/01/2022 04:17 amQuote from: M.E.T. on 11/30/2022 03:13 amThe issue is not about us physically meeting them. It’s about us SEEING (or rather NOT seeing) evidence of their civilizations in their home galaxies. The older they are the more visible an effect these “grabby aliens” should have on their stellar neighbourhood. To explain this lack of detection, the Grabby Alien hypothesis says that those old enough to have visibly changed their stellar environments HAVE to be far enough away that the light of their civilization has not had time to reach us yet.So a “mega structure / stellar engineering capable” civilization could have arisen 500M years ago in a galaxy 1B light years away, but it is not allowed to have arisen in the next door Andromeda galaxy more than 2.5 million years ago. Or in the Milky Way itself more than ~100K years ago. Else we would see evidence of it.So the theory requires that the older a civilization is, the farther away from Earth it has to be. That’s a weird, rather Earth-centric condition that has no logical or natural reason for existing, other than to make the theory work.But the reason why the grabbies have to be farther away, is because if they weren't, then they'd likely have already grabbed us by now. The older they are, the grabbier they can be, since their engineering capabilities only grow with time, and their Von Neumann swarms have more time to grow in size and voraciousness (provided their own swarms don't swarm back at them)Why is it that "the simpler alternative is that they’re just not there in the first place" ?? Why is that simpler?Simpler that they're not there? Or simpler that they're just not grabby?That’s a bit like arguing the reason the boogeyman has to be on Easter Island rather in New York is because if he was in New York he would have attacked us by now.EDITIf you don’t see any aliens, surely it is simpler to argue they are not there (until evidence proves otherwise), than to contrive an answer where they HAVE to be there, but they all just happen to be at a distance where their age does not allow their light to have reached us yet. There could be multiple 5 billion year old civilizations, but according to this theory they just happen to all be more than 5 billion light years away. When in reality their distribution should be random, as the Milky Way or Andromeda is just as old as galaxies 5 or 10 billion light years away.There's a video on YouTube from one of the co-authors of the paper proposing the grabby aliens hypothesis that shows a 3D simulation of a median scenario in their model:The first grabby alien civilizations only appear about 6 billions years after the Big Bang due to the lack of heavy elements in Population III and II stars formed in the early universe. After 13.8 billion years, the majority of the observable universe is within a grabby alien civilization, but large gaps still exist where observers would see no obvious sign of aliens in their observable universes. To your point about multiple 5 billion year old civilizations, this particular sim shows only about 8-10 existing grabby alien civs in the observable universe 5 billion years ago; if evenly distributed, their origin points would be separated by over 5 billion light years on average today, and when randomly distributed there would be smaller and large gaps. "Older civilization far, newer civilization closer" is therefore unsurprising, given how incredibly rare grabby aliens are (only 87 appear in total for this particular simulation over the 20 billion years it takes for the observable universe to be full).The grabby aliens model doesn't "contrive an answer where they HAVE to be there", it hypothesizes the existence of grabby aliens (defined as civilizations that expand quickly and radically modify stars and galaxies for their use) specifically and explicitly to explain why humans have appeared very early in the universe's history without rejecting the Copernican principle: it proposes that we aren't special, and have in fact appeared close to the end of the time in the universe when we could have possibly spawned before the universe is filled. The model then constrains the appearance rate and expansion speeds of these grabby aliens due to the fact that we don't currently observe them.Of course, everything here assumes that we are not, in fact, extremely special or unique in the timing or presence of our civilization. That we are not alone, and that we have not appeared early due to luck.Feels similar to the probabilistic Doomsday Argument, which makes no practical sense. In this case SOMEONE had to be early. It might as well be us. It doesn’t need invisible grabby aliens to CAUSE our earliness to be normalised.Just like SOMEONE has to win the Powerball lottery draw. However improbable it might be for any specific individual.We just won the cosmic lottery. As will many others over the ensuing trillions of years of the universe’s existence. We just happen to be in the first 13.8 billion years.
Quote from: M.E.T. on 12/01/2022 02:11 pmQuote from: Yiosie on 12/01/2022 09:54 amQuote from: M.E.T. on 12/01/2022 07:56 amQuote from: sanman on 12/01/2022 04:17 amQuote from: M.E.T. on 11/30/2022 03:13 amThe issue is not about us physically meeting them. It’s about us SEEING (or rather NOT seeing) evidence of their civilizations in their home galaxies. The older they are the more visible an effect these “grabby aliens” should have on their stellar neighbourhood. To explain this lack of detection, the Grabby Alien hypothesis says that those old enough to have visibly changed their stellar environments HAVE to be far enough away that the light of their civilization has not had time to reach us yet.So a “mega structure / stellar engineering capable” civilization could have arisen 500M years ago in a galaxy 1B light years away, but it is not allowed to have arisen in the next door Andromeda galaxy more than 2.5 million years ago. Or in the Milky Way itself more than ~100K years ago. Else we would see evidence of it.So the theory requires that the older a civilization is, the farther away from Earth it has to be. That’s a weird, rather Earth-centric condition that has no logical or natural reason for existing, other than to make the theory work.But the reason why the grabbies have to be farther away, is because if they weren't, then they'd likely have already grabbed us by now. The older they are, the grabbier they can be, since their engineering capabilities only grow with time, and their Von Neumann swarms have more time to grow in size and voraciousness (provided their own swarms don't swarm back at them)Why is it that "the simpler alternative is that they’re just not there in the first place" ?? Why is that simpler?Simpler that they're not there? Or simpler that they're just not grabby?That’s a bit like arguing the reason the boogeyman has to be on Easter Island rather in New York is because if he was in New York he would have attacked us by now.EDITIf you don’t see any aliens, surely it is simpler to argue they are not there (until evidence proves otherwise), than to contrive an answer where they HAVE to be there, but they all just happen to be at a distance where their age does not allow their light to have reached us yet. There could be multiple 5 billion year old civilizations, but according to this theory they just happen to all be more than 5 billion light years away. When in reality their distribution should be random, as the Milky Way or Andromeda is just as old as galaxies 5 or 10 billion light years away.There's a video on YouTube from one of the co-authors of the paper proposing the grabby aliens hypothesis that shows a 3D simulation of a median scenario in their model:The first grabby alien civilizations only appear about 6 billions years after the Big Bang due to the lack of heavy elements in Population III and II stars formed in the early universe. After 13.8 billion years, the majority of the observable universe is within a grabby alien civilization, but large gaps still exist where observers would see no obvious sign of aliens in their observable universes. To your point about multiple 5 billion year old civilizations, this particular sim shows only about 8-10 existing grabby alien civs in the observable universe 5 billion years ago; if evenly distributed, their origin points would be separated by over 5 billion light years on average today, and when randomly distributed there would be smaller and large gaps. "Older civilization far, newer civilization closer" is therefore unsurprising, given how incredibly rare grabby aliens are (only 87 appear in total for this particular simulation over the 20 billion years it takes for the observable universe to be full).The grabby aliens model doesn't "contrive an answer where they HAVE to be there", it hypothesizes the existence of grabby aliens (defined as civilizations that expand quickly and radically modify stars and galaxies for their use) specifically and explicitly to explain why humans have appeared very early in the universe's history without rejecting the Copernican principle: it proposes that we aren't special, and have in fact appeared close to the end of the time in the universe when we could have possibly spawned before the universe is filled. The model then constrains the appearance rate and expansion speeds of these grabby aliens due to the fact that we don't currently observe them.Of course, everything here assumes that we are not, in fact, extremely special or unique in the timing or presence of our civilization. That we are not alone, and that we have not appeared early due to luck.Feels similar to the probabilistic Doomsday Argument, which makes no practical sense. In this case SOMEONE had to be early. It might as well be us. It doesn’t need invisible grabby aliens to CAUSE our earliness to be normalised.Just like SOMEONE has to win the Powerball lottery draw. However improbable it might be for any specific individual.We just won the cosmic lottery. As will many others over the ensuing trillions of years of the universe’s existence. We just happen to be in the first 13.8 billion years.I also thought of the Doomsday Argument when first reading about this, and saw that Robin Hanson had previously rejected it comprehensively. So I guess there must be some distinction between it and the grabby aliens hypothesis that I don't understand.Yes, it is very possible that we are early due to luck (that's my personal stance on the question too). Just wanted to focus the discussion back to the hypothesis that inspired the video in the first post. The authors of the paper thought that "someone has to be early, and it might as well be us" ought to be countered with an explanation rooted in the Copernican principle to consider before leaving it up to dumb luck. Their answer is "we're actually not early; we're in the middle of the distribution of emerging spacefaring civilizations", and grabby aliens is their attempt to take that possibility to a logical conclusion.In any case it was fun to put aside my own priors and explore this hypothesis here.
Quote from: TrevorMonty on 11/12/2022 07:23 amStatistical we wouldn't be first or last. There are trillions of planets out there. Life on earth has existed for few 100million years and we've gone from ape to spacefaring in 100,000years.Evolution does not have a purpose or a goal, and it does not necessarily select for complexity or intelligence. Simple / Bacterial life forms ruled the Earth for ~4 billion years. There is no particular reason, that we know of anyway, that they could not have continued to be the dominant life form for tens of billions of years. There may be trillions of planets out there with such simple life, but that does not guarantee they will eventually produce an intelligent species that creates a civilization. Even using Earth as an example, it is statistically very unlikely. We are the only one of many billions of the complex species on Earth that has developed the high level of intelligence we have. And even if a species develops intelligence, it may not have the capability or resources to produce technology. A human-intelligent dolphin could never smelt metals and build a radio, for example. Or their planet may not have a crust rich in workable metals, or they don't have any animals suitable for domestication, or crop plants that can be grown en mass with storable seeds for food during lean seasons / years. Humanity really hit the jackpot with a large amount of exploitable resources on our planet. It's also possible also that supernovae and gamma ray bursts extinguish life in large areas of the galaxy (one of the several possible Great Filters). Anyway, when I plug in my personal estimates into the Drake equation, I get maybe 5 technological civilizations in our galaxy. I don't think we are alone, but I think it may be a very long time before we find another intelligent, technology-making civilization. It is entirely possible we are the first (at least in our galaxy or in our region of the galaxy) to be able to leave our home planet.