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It may be even worse, that different continent is on a different planet. Space(time) is absolutely, mind-boggling massive. Everyone knows it's big but it hard

It may be even worse, that different continent is on a different planet. Space(time) is absolutely, mind-boggling massive. Everyone knows it's big but it hard to comprehend how big and why there could be many alien civilizations out there capable of broadcasting or detecting but never intersect in any way because the detection windows of any 2 civilizations don't line up. The Milky Way alone is ~150000-200000 light years across. Humans have been civilized for only some tens of thousands of years, and capable of sending and receiving signals for a mere century. Imagine that even at the speed of light the entire history of civilized life on Earth might come and go many times before something reaches us, or before the probe comes back. There's no Earth-bound or common sense analogy that can convey this kind of vastness and emptiness.

vmception 6y ago
The fermi paradox does convey this.
- bena 6y ago
  Not well. It makes the assumptions that all of the problems with space travel are logistically possible.
  - deeeeplearning 6y ago
    Given the age of the Milky Way, a civilization using even slow sub light travel with generation ships or autonomous probes could have colonized the entire galaxy many times over. Why has no one done that? Hence the paradox.
    - eloff 6y ago
      I don't know why this got down-voted. The milky way is 100K light years across. It's 13.5 billion years old. It's entirely possible to blanket the whole galaxy with probes, without even getting into self replicating probes.
      - e12e 6y ago
        You have to make an assumption about speed - it certainly won't be more than a tiny fraction light speed. Eg voyager appear to travel now at less than 0.00006 c (16 km/s). Than turns 100k light years into ballpark 150 M year journey (no it doesn't its 1.8 bn years as mentioned in reply) . Still possible to cross 10.000 times - but that would be a straight line. I suspect the distances will grow somewhat fractally if you want to swing by any stars? (ed: so, not really very likely at all)
        Baeocystin 6y ago
        To traverse 100k light-years at 16km/s would take approximately 1.8 billion years. FWIW.
        e12e 6y ago
        Thanks, not sure how I got to just 150 mill years.
        mistersquid 6y ago
        > Than turns 100k light years into ballpark 150 year journey. Forgive my confusion. If 100K light years is 100K years at c, how can > 0.00006 c yield 0.00150K (150) years?
        e12e 6y ago
        It can't (unless you mistype into your plain android calculator app). Ed: Fwiw there was a typo there, too - it was supposed to say 150 million - but it's more like 1.5 billion.
        sliken 6y ago
        There's current projects on earth seriously working on getting probes up to 1% of the speed of light. Just a small/light weight probe, a solar sail, and a large (but feasible) array of lasers.
        eloff 6y ago
    - deeeeplearning 6y ago
      Not sure why it was downvoted. Many people have looked into this. https://gtocx.jpl.nasa.gov/gtocx/competition/ https://gtocx.jpl.nasa.gov/gtocx/competition/ Even entire competitions to find optimal colonization methods. Could take 90M years with measly future human tech. Age of Milky Way is 13.5 Billion so even conservatively you could indeed colonize the galaxy many many times over in that time.
      - Retric 6y ago
        The Milky Way lacked rocky planets early on, making that 12.5 Billion year age largely meaningless. Which is just one of many bad assumptions in how people do these calculations. At a minimum you don’t get a straight path from A to B. Assuming any kind of limitation in distance traveled and your at the mercy of the distribution of whatever resource you need. Aka need rocky planets with liquid water, that’s likely going to be an very indirect path. Even just non binary star systems is significant. Further, assuming every trip is successful is again unlikely. How long you need to wait before the next trip is again a major qualifier. For example, what happens if they first send a probe to verify habitability? Suddenly travel times more than double. I have seen plenty of optimistic calculations that still add up to over a billion years before total colonization and sometimes much much higher than that. And that’s a billion years where expansion is a major priority at the frontier. Look at successful colonizations that don’t expand rapidly and again things keep slowing down.
        mylons 6y ago
        If you used the Von Neumann machine approach wouldn’t it not really matter if the planet was habitable or not?
        Retric 6y ago
        Let’s assume your sending a Von Neumann probe to prep the way for your ship. Now it shows up and does whatever it needs to and then sends an everything is ready signal before you send your generation ship. I mean sure you could in theory send out an endlessly replicating probe that keeps going to other star systems, but that’s even more risky.
    - bena 6y ago
      Yes, I know the paradox. It's simple. It's too simple. It has huge assumptions. Namely the assumption that the current problems to colonization can be solved in a cost-effective manner. The longest continuous length of time spent in what limited space flight we have is just under 440 days. Not to mention, all of it was spent in low Earth orbit. Once we go beyond that, we lose all protection from the Earth's magnetosphere. Then there's also the loss of bone density due to lack of gravity. 1% per month is nothing to sneeze at. We are not built for space travel. We are built to inhabit this planet. We have evolved to the conditions here. And before you say that the generation ships will just fake gravity and have appropriate shielding. Where do you get that assumption? We can't fake gravity. We have a space station where they take 10 times the radiation as here on Earth because we can't even realistically shield that. And then we get to "autonomous probes", the great handwave of people who think they can cleverly sidestep the "humans aren't built for space" issue. Who builds them? For what purpose? What's our expected return? How can you justify the investment in time and resources to shoot into space, with absolutely no hope of even knowing there's a chance for a return on that investment until generations later, a probe that can at best return data. And then there's the issue of it being an autonomous probe. Two words that hide a lot of other problems. A lot of other assumptions. One being that we'll have created an intelligence capable of running this thing. In other words, the Fermi Paradox just assumes that all of these incredibly hard problems can and will be solved and that the solutions are logistically viable. What if they're not?
      - deeeeplearning 6y ago
        You talk like this is all expected to be done by 21st century humans when in reality if there were civilizations out there capable of doing this colonization they would likely be millions of years our elders and its incredibly foolish to try to guess their intentions or the capabilities of their technology. Your view is painfully anthropocentric. Just to add, there are plenty of valid criticisms or plausible solutions to the Fermi paradox but I think you've failed to identify a single one.
        bena 6y ago
        You talk like this is all a forgone conclusion. Technology is not magic. Time is not a salve that solves all issues. You say that my view is "painfully anthropocentric", but how? It seems your only response is "but aliens". That is not good enough. You want to say that it is foolish of me to try and guess their intentions and capabilities, but that's what the paradox does as well. It assumes their intentions are to colonize and their capabilities allow it. With no proof. The only life we have to base anything off of is right here. And if you think I haven't identified a single valid criticism of the Fermi paradox, then I'm just going to assume you aren't aware of the criticisms. I've basically touched on this one https://en.wikipedia.org/wiki/Fermi_paradox#Economic_explanations https://en.wikipedia.org/wiki/Fermi_paradox#Economic_explana... So no, I'm not saying that just because it can't be done now, it can't be done ever. I'm saying the Fermi Paradox is basically saying "Once you solve these incredibly hard problems, this becomes easy." I think the Fermi Paradox is phrased wrong. It should state that if it were possible to colonize the galaxy, it would have been done by now.
    - tsimionescu 6y ago
      There are problems of resiliency and energy storage that could be more or less fundamental problems. It could take millions if years of technological civilization to produce a machine capable of sustaining life for the hundreds of thousands of years necessary for interstellar travel, and civilizations may tend to collapse for various reasons before reaching such technological peaks. It's also entirely possible that we are the first, or one of the first, technological civilizations in the galaxy. Given how little we understand about the appearance of life, the emergence of multicellular life from single cell life, and the emergence of intelligence from multicellular life, there's not way to put an estimate on these probabilities. Think about the fact that in 3.5 billion years there hasn't been any new abiogenesis on the only planet in the universe we know for sure can sustain life, and in this billion years a single life form has ever evolved from a single-cell to multi-cellular life, aren't the priors pretty decent that life is an extremely rare phenomenon? Given the fact that the Milky Way is somewhere around 13 billion years old, how often can we expect a once in 3.5 billion years event have happened?
      - Baeocystin 6y ago
        >Think about the fact that in 3.5 billion years there hasn't been any new abiogenesis on the only planet in the universe we know for sure can sustain life, and in this billion years a single life form has ever evolved from a single-cell to multi-cellular life, aren't the priors pretty decent that life is an extremely rare phenomenon? Any freshly-evolved life would have to compete with organisms that have already been honing their survival strategies for literal billions of years. There's no reason to think such a thing is possible, and the lack of it doesn't speak one way or another to the difficulty of it happening in a virgin environment.
      - tzs 6y ago
        > It could take millions if years of technological civilization to produce a machine capable of sustaining life for the hundreds of thousands of years necessary for interstellar travel. For a generation ship, are you referring to all the machinery that can maintain a balanced ecosystem of plants and animals and humans in order to provide food for the people during the trip to the new planet, and to make all the things needed to keep those people healthy during the trip such as medicine and drugs? If so, there may be a way around that. Send all your colonists as frozen embryos or frozen sperm and eggs. Your ship only needs life support then to keep alive the people who run the ship. For food, don't grow it. Take it with you. At first taking your food with you seems absurd, but if you had a food with the same caloric density as rice, enough of it to provide 2000 calories/day to one human for 100k years would fit in a sphere with a radius of 24.4 meters. So once your technological civilization figures out a way to preserve food such that they can make a rice ball equivalent with a 100k year storage life, a generation ship with a small crew becomes a whole lot more feasible. For replacement crew throughout the journey, you can do a mix of using whatever kids the crew produces the old fashioned way and using kids produced from some of the frozen embryos/eggs/sperm. I think technological civilizations will reach the point of being able to do this well before they are millions of years old. We aren't too far from being able to do it ourselves. We are probably farther out on the propulsion for the ship itself.
    - jcims 6y ago
      I'm fairly confident we'll eventually find that our form of life is the result of intentional or unintentional colonization of Earth. If you look at how quickly life began after the oceans settled out, then look at precisely how complex even the most primitive forms of life are (in terms of likelihood of stochastic construction to the point of sophistication to support evolutionary mechanisms) it seems incredibly unlikely that we originated here.
      - Osiris 6y ago
        This is an interesting idea. Look at how religion explains the origin of life: A lifeform not from this planet, far more advanced than us, gave "the breath of life", and calls us their "children". The vastness of this universe leads me to believe that it's impossible to dismiss the idea that there is an intelligence/lifeform sufficiently advanced as to appear to be a God to us.
        jcims 6y ago
        Totally agree. Joscha Bach laid out a few interesting ideas around this at the end of a podcast. If you have a few minutes start here for a broader context (starts of wholly unrelated but with some great concepts): https://youtu.be/P-2P3MSZrBM?t=10084 https://youtu.be/P-2P3MSZrBM?t=10084 If not, he drills into it here: https://youtu.be/P-2P3MSZrBM?t=10400 https://youtu.be/P-2P3MSZrBM?t=10400
        psychoslave 6y ago
        That doesn't explain where the said intelligence /lifeform would come from itself, so what the point of such a theory?
        sliken 6y ago
        I read a short story that explained the explosion of life on earth during a very short period on some alien that didn't follow protocol and dumped some poop.
      - marta_morena_28 6y ago
        Possible, but far reaching. There are other explanations: * We are a computer simulation (hence there is no colonization, we are in an experiment) * There are like 1,000,000,000,000,000,000 habitable planets in the universe. Just because something is "extremely unlikely" doesn't mean that it didn't happen to us. I.e. whomever this happened to, would ask himself that question. We may just be the ones it happened to. Also: Why would they settle species from millions of years in their own past. If they wanted to colonize, they could start with their own life-forms. Could be several things as well: * We are a genesis project and they will simply come back later and settle in what we left behind (i.e. they let the ecosystem build for a few million years before trying out this settlement) * They don't want to create competitors * We are a population bomb, i.e. they just sent out billions of probes trying to populate any given habitable planet, and they couldn't just spawn themselves there and instead had to start from somewhere where a sustainable ecosystem would derive from
    - tzs 6y ago
      It could be that none of them have seen any point in doing so. Generally on Earth colonization has happened in order to provide a tangible economic benefit to those supporting the colonization effort. With someplace that you can only travel to and from by slow generation ship its hard to find any such economic benefit in having a colony there.
- vl 6y ago
  Basically there is not need and motivation for humans to colonize anything outside the Earth. It's just too far, too expensive and too uncomfortable. Humans evolved specifically to live on Earth, to live somewhere else, they need to be severely altered. Now you just seeded civilization of another species, that might turn out to be confrontational or outright hostile. Why would you do that? Too see how well this works out on the local scale see colonization of Americas.
  - dyingkneepad 6y ago
    > Basically there is not need and motivation for humans to colonize anything outside the Earth. Our current gas emissions would disagree. Also, asteroids, gamma ray bursts, curiosity, sheer ambition, etc, etc. The thing is: we don't need to convince all of mankind to colonize another planet. All it takes is a few people. Crazy rich Mr. Musk is one example. He may not be able to achieve it, but maybe all we need is a few other Musks in the next generations and suddenly we'll be in other planets. The Fermi Paradox discussion is fascinating.
    - AndyPa32 6y ago
      > Our current gas emissions would disagree. While at first it might seem that Mars or any other planet is the solution to our environmental problem, the easiest solution to the problem would be fixing this planet. Colonizing Mars would take up so many resources that fixing Earth might be more cost-effective.
      - psychoslave 6y ago
        This is not Earth that needs to be fixed, it's human behavior. Teraformation and space conquest are fassinating topics, but "fixing our behavior to avoid to fuck up the only accessible viable environment we have" is far from deserving only a mere "might be more cost-effective".
      - dyingkneepad 6y ago
        But way less fun :) Or we could, you know, just transfer our consciousness to machines that can easily survive Mars and other environments and start our colonization after declaring ourselves to be Homo-sapiens-machina.
beamatronic 6y ago
That’s why the best thing any species can do for the other species is to leave signs that we were once here.
- buran77 6y ago
  We still need to leave a heck of a collection. On a living, evolving planet if all civilizations are gone the signs get wiped out pretty fast in geological time (geology, weather), and in space the signs are usually traveling in the emptiness with little chances of being spotted. The best probes will eventually fail and will just add to the countless objects floating never to encounter anything. I know it sounds depressing but I keep getting reminded of this [0] when thinking of loneliness in the universe. It's the most apt description I came across in recent memory. [0] https://www.theoatmeal.com/comics/oracle https://www.theoatmeal.com/comics/oracle
  - njarboe 6y ago
    On the other hand, large objects made by us on the Moon could last for 100's of millions of years. Especially if the object was designed to last that long.
  - beamatronic 6y ago
    I like the comic. It's almost like all intelligent life in the universe was put into escape-proof cages. We need to rage against this! Do it for all the others who can't.
theandrewbailey 6y ago
I remember reading somewhere that due to the differing pace of evolution and technology advancements, any intelligent living aliens we meet are almost certainly going to be gods or cavemen. I can't find the reference.
- krapp 6y ago
  It's from Arthur C. Clarke: "If one considers the millions of years of pre-history, and the rapid technological advancement occurring now, if you apply that to a hypothetical alien race, one can figure the probabilities of how advanced the explorers will find them. The conclusion is we will find apes or angels, but not humans." [0]http://www.projectrho.com/public_html/rocket/alientech.php http://www.projectrho.com/public_html/rocket/alientech.php
  - kfarr 6y ago
    I like that quote but lately feeling like advanced tech doesn't necessarily mean angelic
    - krapp 6y ago
      Angelic doesn't imply good, just being sufficiently advanced enough to seem like magic (to use another Clarke quote.) Demons are technically angels after all.
      - zabardasth 6y ago
        > And she took on another heart—no longer minded toward earthly things—but ecstatically in the angelic dialect, sending up a hymn to God in accord with the style of the angels. And as she spoke ecstatically, she allowed “The Spirit” to be on her garment. It seems that speaking to one would be quite a terrifying experience, especially if one were speaking in tongues.
        krapp 6y ago
        When angels are described in the Bible, it's often in strange and abstract terms, beings with multiple faces, legs made of burning bronze, eyes where eyes shouldn't be, etc. As if the writer was having difficulty comprehending what they were seeing,much less finding language for it. And the first thing angels do when they encounter humans is tell them not to be afraid, because of course the logical and proper reaction to skyscraper-sized interlocking, burning, eye-covered wheels with multi-faced, multi-winged beings in the middle is bowel evacuating terror. And of course, many of Lovecraft's eldritch horrors were simply aliens that were so alien that the mere sight of them broke human minds, and that were no more concerned for humanity than humanity is for a particular anthill. That's probably what an actual encounter with an alien is going to be like for us. We'll try to understand why a living infinite-dimensional hypersphere made of flesh made of time whose eyes are our eyes all at once just showed up and "unfolded" our sun into a non-Euclidean shape we can't even describe mathematically without being driven slowly to madness, while it won't even know we were there.
anonAndOn 6y ago
While interstellar travel would be impossible using conventional thrust in a straight line, could you overcome the distance by bending space time?[0] [0]https://www.nasa.gov/centers/glenn/technology/warp/gravstat.html https://www.nasa.gov/centers/glenn/technology/warp/gravstat....
- ben_w 6y ago
  Going fast in a straight line with conventional rockets is achievable, just not very timely. Bending spacetime enough to make a difference — even just to the time taken between here and Alpha Centauri — is beyond any known mechanism humans could build, even in principle, using the total resources of our entire solar system. (Using unknown mechanisms: perhaps, but they’re unknown)
  - skissane 6y ago
    > Going fast in a straight line with conventional rockets is achievable, just not very timely. A constant-acceleration spacecraft could reach the opposite side of the galaxy in 24 years ship time. (That'd be over 100,000 years of Earth time, however.) Conventional chemical propulsion don't have high enough impulse to do that. Possibly some kind of nuclear or matter-antimatter propulsion could?
    - ben_w 6y ago
      Everything would run out of fuel over that distance if you were constantly accelerating ahead [0], but you don’t need to constantly accelerate in space. [0] spinning is accelerating, and you can do that forever, but it won’t help you get anywhere
    - avhon1 6y ago
      Atomic Rockets has some good info on this. > When it comes to [high thrust, high specific impulse] propulsion systems we might actually be able to build in the near future, the list includes Orion drives, Zubrin's nuclear salt water rocket, and maybe Medusa. There have been many studied variations of Orion. Atomic Rockets cites hypothetical Isp between 3,000 and 12,000 seconds. Vehicles with delta-V of up to 100,000 m/s have been proposed. These could definitely be built, and would definitely work, but would require constructing, co-locating, launching, and detonating thousands of 5- to 15-kiloton nuclear explosives. http://www.projectrho.com/public_html/rocket/enginelist3.php#boomboom http://www.projectrho.com/public_html/rocket/enginelist3.php... Medusa is basically Orion crossed with the image of a sailor blowing into their own sails. A huge parachute is deployed in front of the spaceship, and the nuclear explosives are detonated between it and the bow of the spaceship. The parachute can capture more of the explosive output than Orion's pusher plate can, it weighs less (because all of its members are in tension), and it can use its rigging's elastic properties to dampen the intermittent thrust, as opposed to Orion's (heavier) hydraulic dampers. The proposal study for Medusa (which assumed thirty 25-kg explosives) came up with an Isp of 106,220 seconds, and a delta-V of 4775 m/s. http://www.projectrho.com/public_html/rocket/enginelist3.php#medusa http://www.projectrho.com/public_html/rocket/enginelist3.php... The Nuclear Salt Water Rocket assumes plausible (but completely untested, so maybe impossible) continuous nuclear fission in a stream of uranium-salt-y water being sprayed into the combustion chamber. Assuming that this can be made to not blow itself up, 20%-enriched salt nets a theoretical Isp of ~7,000 seconds, and 90%-(weapons-grade) enriched fuel, with somewhat more optimistic efficiency assumptions, has a theoretical Isp of ~400,000 seconds and a delta-V of 10,000,000 m/s. http://www.projectrho.com/public_html/rocket/enginelist2.php#nswr http://www.projectrho.com/public_html/rocket/enginelist2.php... There are also lots of other currently-less-plausible proposals for high-power high-efficiency rockets. (Many of them assume things like efficient proton-proton fusion, which might be possible, but we have no idea how to do it.) Atomic Rockets is a great website for reading about these. My takeaway is that it's almost certainly possible to build spaceships that can travel at >0.01c, but it would take a great deal of resources organized by a society that is more trusting and responsible than we are now. After all, any vehicle with that kind of power is also an equally powerful weapon.
dylan604 6y ago
> Humans have been civilized for only some tens of thousands of years, That's giving humans a lot of credit. Civility has been regressing. I would be embarrassed for another civilization to find us now. Sure, we may have more technology and scientific understanding, but how we treat one another needs another world than civil.
- sbelskie 6y ago
  I don’t think civility has a lot to with civilization in the anthropological sense of the word.
  - dylan604 6y ago
    "...first use in English is attributed to Adam Ferguson, who in his 1767 Essay on the History of Civil Society wrote, "Not only the individual advances from infancy to manhood but the species itself from rudeness to civilisation".[14] The word was therefore opposed to barbarism or rudeness, in the active pursuit of progress characteristic of the Age of Enlightenment." [0] [0]https://en.wikipedia.org/wiki/Civilization https://en.wikipedia.org/wiki/Civilization
    - sbelskie 6y ago
      “... in the anthropological sense of the word.” -me, just recently. If you are wondering where we might find a definition matching that sense, try the first sentence of the article you linked: “A civilization (or civilisation) is any complex society characterized by urban development, social stratification, a form of government and symbolic systems of communication such as writing.”

vmception 6y ago

The fermi paradox does convey this.

bena 6y ago
Not well. It makes the assumptions that all of the problems with space travel are logistically possible.
- deeeeplearning 6y ago
  Given the age of the Milky Way, a civilization using even slow sub light travel with generation ships or autonomous probes could have colonized the entire galaxy many times over. Why has no one done that? Hence the paradox.
  - eloff 6y ago
    I don't know why this got down-voted. The milky way is 100K light years across. It's 13.5 billion years old. It's entirely possible to blanket the whole galaxy with probes, without even getting into self replicating probes.
    - e12e 6y ago
      You have to make an assumption about speed - it certainly won't be more than a tiny fraction light speed. Eg voyager appear to travel now at less than 0.00006 c (16 km/s). Than turns 100k light years into ballpark 150 M year journey (no it doesn't its 1.8 bn years as mentioned in reply) . Still possible to cross 10.000 times - but that would be a straight line. I suspect the distances will grow somewhat fractally if you want to swing by any stars? (ed: so, not really very likely at all)
      - Baeocystin 6y ago
        To traverse 100k light-years at 16km/s would take approximately 1.8 billion years. FWIW.
        e12e 6y ago
        Thanks, not sure how I got to just 150 mill years.
      - mistersquid 6y ago
        > Than turns 100k light years into ballpark 150 year journey. Forgive my confusion. If 100K light years is 100K years at c, how can > 0.00006 c yield 0.00150K (150) years?
        e12e 6y ago
        It can't (unless you mistype into your plain android calculator app). Ed: Fwiw there was a typo there, too - it was supposed to say 150 million - but it's more like 1.5 billion.
      - sliken 6y ago
        There's current projects on earth seriously working on getting probes up to 1% of the speed of light. Just a small/light weight probe, a solar sail, and a large (but feasible) array of lasers.
      - eloff 6y ago
  - deeeeplearning 6y ago
    Not sure why it was downvoted. Many people have looked into this. https://gtocx.jpl.nasa.gov/gtocx/competition/ https://gtocx.jpl.nasa.gov/gtocx/competition/ Even entire competitions to find optimal colonization methods. Could take 90M years with measly future human tech. Age of Milky Way is 13.5 Billion so even conservatively you could indeed colonize the galaxy many many times over in that time.
    - Retric 6y ago
      The Milky Way lacked rocky planets early on, making that 12.5 Billion year age largely meaningless. Which is just one of many bad assumptions in how people do these calculations. At a minimum you don’t get a straight path from A to B. Assuming any kind of limitation in distance traveled and your at the mercy of the distribution of whatever resource you need. Aka need rocky planets with liquid water, that’s likely going to be an very indirect path. Even just non binary star systems is significant. Further, assuming every trip is successful is again unlikely. How long you need to wait before the next trip is again a major qualifier. For example, what happens if they first send a probe to verify habitability? Suddenly travel times more than double. I have seen plenty of optimistic calculations that still add up to over a billion years before total colonization and sometimes much much higher than that. And that’s a billion years where expansion is a major priority at the frontier. Look at successful colonizations that don’t expand rapidly and again things keep slowing down.
      - mylons 6y ago
        If you used the Von Neumann machine approach wouldn’t it not really matter if the planet was habitable or not?
        Retric 6y ago
        Let’s assume your sending a Von Neumann probe to prep the way for your ship. Now it shows up and does whatever it needs to and then sends an everything is ready signal before you send your generation ship. I mean sure you could in theory send out an endlessly replicating probe that keeps going to other star systems, but that’s even more risky.
  - bena 6y ago
    Yes, I know the paradox. It's simple. It's too simple. It has huge assumptions. Namely the assumption that the current problems to colonization can be solved in a cost-effective manner. The longest continuous length of time spent in what limited space flight we have is just under 440 days. Not to mention, all of it was spent in low Earth orbit. Once we go beyond that, we lose all protection from the Earth's magnetosphere. Then there's also the loss of bone density due to lack of gravity. 1% per month is nothing to sneeze at. We are not built for space travel. We are built to inhabit this planet. We have evolved to the conditions here. And before you say that the generation ships will just fake gravity and have appropriate shielding. Where do you get that assumption? We can't fake gravity. We have a space station where they take 10 times the radiation as here on Earth because we can't even realistically shield that. And then we get to "autonomous probes", the great handwave of people who think they can cleverly sidestep the "humans aren't built for space" issue. Who builds them? For what purpose? What's our expected return? How can you justify the investment in time and resources to shoot into space, with absolutely no hope of even knowing there's a chance for a return on that investment until generations later, a probe that can at best return data. And then there's the issue of it being an autonomous probe. Two words that hide a lot of other problems. A lot of other assumptions. One being that we'll have created an intelligence capable of running this thing. In other words, the Fermi Paradox just assumes that all of these incredibly hard problems can and will be solved and that the solutions are logistically viable. What if they're not?
    - deeeeplearning 6y ago
      You talk like this is all expected to be done by 21st century humans when in reality if there were civilizations out there capable of doing this colonization they would likely be millions of years our elders and its incredibly foolish to try to guess their intentions or the capabilities of their technology. Your view is painfully anthropocentric. Just to add, there are plenty of valid criticisms or plausible solutions to the Fermi paradox but I think you've failed to identify a single one.
      - bena 6y ago
        You talk like this is all a forgone conclusion. Technology is not magic. Time is not a salve that solves all issues. You say that my view is "painfully anthropocentric", but how? It seems your only response is "but aliens". That is not good enough. You want to say that it is foolish of me to try and guess their intentions and capabilities, but that's what the paradox does as well. It assumes their intentions are to colonize and their capabilities allow it. With no proof. The only life we have to base anything off of is right here. And if you think I haven't identified a single valid criticism of the Fermi paradox, then I'm just going to assume you aren't aware of the criticisms. I've basically touched on this one https://en.wikipedia.org/wiki/Fermi_paradox#Economic_explanations https://en.wikipedia.org/wiki/Fermi_paradox#Economic_explana... So no, I'm not saying that just because it can't be done now, it can't be done ever. I'm saying the Fermi Paradox is basically saying "Once you solve these incredibly hard problems, this becomes easy." I think the Fermi Paradox is phrased wrong. It should state that if it were possible to colonize the galaxy, it would have been done by now.
  - tsimionescu 6y ago
    There are problems of resiliency and energy storage that could be more or less fundamental problems. It could take millions if years of technological civilization to produce a machine capable of sustaining life for the hundreds of thousands of years necessary for interstellar travel, and civilizations may tend to collapse for various reasons before reaching such technological peaks. It's also entirely possible that we are the first, or one of the first, technological civilizations in the galaxy. Given how little we understand about the appearance of life, the emergence of multicellular life from single cell life, and the emergence of intelligence from multicellular life, there's not way to put an estimate on these probabilities. Think about the fact that in 3.5 billion years there hasn't been any new abiogenesis on the only planet in the universe we know for sure can sustain life, and in this billion years a single life form has ever evolved from a single-cell to multi-cellular life, aren't the priors pretty decent that life is an extremely rare phenomenon? Given the fact that the Milky Way is somewhere around 13 billion years old, how often can we expect a once in 3.5 billion years event have happened?
    - Baeocystin 6y ago
      >Think about the fact that in 3.5 billion years there hasn't been any new abiogenesis on the only planet in the universe we know for sure can sustain life, and in this billion years a single life form has ever evolved from a single-cell to multi-cellular life, aren't the priors pretty decent that life is an extremely rare phenomenon? Any freshly-evolved life would have to compete with organisms that have already been honing their survival strategies for literal billions of years. There's no reason to think such a thing is possible, and the lack of it doesn't speak one way or another to the difficulty of it happening in a virgin environment.
    - tzs 6y ago
      > It could take millions if years of technological civilization to produce a machine capable of sustaining life for the hundreds of thousands of years necessary for interstellar travel. For a generation ship, are you referring to all the machinery that can maintain a balanced ecosystem of plants and animals and humans in order to provide food for the people during the trip to the new planet, and to make all the things needed to keep those people healthy during the trip such as medicine and drugs? If so, there may be a way around that. Send all your colonists as frozen embryos or frozen sperm and eggs. Your ship only needs life support then to keep alive the people who run the ship. For food, don't grow it. Take it with you. At first taking your food with you seems absurd, but if you had a food with the same caloric density as rice, enough of it to provide 2000 calories/day to one human for 100k years would fit in a sphere with a radius of 24.4 meters. So once your technological civilization figures out a way to preserve food such that they can make a rice ball equivalent with a 100k year storage life, a generation ship with a small crew becomes a whole lot more feasible. For replacement crew throughout the journey, you can do a mix of using whatever kids the crew produces the old fashioned way and using kids produced from some of the frozen embryos/eggs/sperm. I think technological civilizations will reach the point of being able to do this well before they are millions of years old. We aren't too far from being able to do it ourselves. We are probably farther out on the propulsion for the ship itself.
  - jcims 6y ago
    I'm fairly confident we'll eventually find that our form of life is the result of intentional or unintentional colonization of Earth. If you look at how quickly life began after the oceans settled out, then look at precisely how complex even the most primitive forms of life are (in terms of likelihood of stochastic construction to the point of sophistication to support evolutionary mechanisms) it seems incredibly unlikely that we originated here.
    - Osiris 6y ago
      This is an interesting idea. Look at how religion explains the origin of life: A lifeform not from this planet, far more advanced than us, gave "the breath of life", and calls us their "children". The vastness of this universe leads me to believe that it's impossible to dismiss the idea that there is an intelligence/lifeform sufficiently advanced as to appear to be a God to us.
      - jcims 6y ago
        Totally agree. Joscha Bach laid out a few interesting ideas around this at the end of a podcast. If you have a few minutes start here for a broader context (starts of wholly unrelated but with some great concepts): https://youtu.be/P-2P3MSZrBM?t=10084 https://youtu.be/P-2P3MSZrBM?t=10084 If not, he drills into it here: https://youtu.be/P-2P3MSZrBM?t=10400 https://youtu.be/P-2P3MSZrBM?t=10400
      - psychoslave 6y ago
        That doesn't explain where the said intelligence /lifeform would come from itself, so what the point of such a theory?
      - sliken 6y ago
        I read a short story that explained the explosion of life on earth during a very short period on some alien that didn't follow protocol and dumped some poop.
    - marta_morena_28 6y ago
      Possible, but far reaching. There are other explanations: * We are a computer simulation (hence there is no colonization, we are in an experiment) * There are like 1,000,000,000,000,000,000 habitable planets in the universe. Just because something is "extremely unlikely" doesn't mean that it didn't happen to us. I.e. whomever this happened to, would ask himself that question. We may just be the ones it happened to. Also: Why would they settle species from millions of years in their own past. If they wanted to colonize, they could start with their own life-forms. Could be several things as well: * We are a genesis project and they will simply come back later and settle in what we left behind (i.e. they let the ecosystem build for a few million years before trying out this settlement) * They don't want to create competitors * We are a population bomb, i.e. they just sent out billions of probes trying to populate any given habitable planet, and they couldn't just spawn themselves there and instead had to start from somewhere where a sustainable ecosystem would derive from
  - tzs 6y ago
    It could be that none of them have seen any point in doing so. Generally on Earth colonization has happened in order to provide a tangible economic benefit to those supporting the colonization effort. With someplace that you can only travel to and from by slow generation ship its hard to find any such economic benefit in having a colony there.
vl 6y ago
Basically there is not need and motivation for humans to colonize anything outside the Earth. It's just too far, too expensive and too uncomfortable. Humans evolved specifically to live on Earth, to live somewhere else, they need to be severely altered. Now you just seeded civilization of another species, that might turn out to be confrontational or outright hostile. Why would you do that? Too see how well this works out on the local scale see colonization of Americas.
- dyingkneepad 6y ago
  > Basically there is not need and motivation for humans to colonize anything outside the Earth. Our current gas emissions would disagree. Also, asteroids, gamma ray bursts, curiosity, sheer ambition, etc, etc. The thing is: we don't need to convince all of mankind to colonize another planet. All it takes is a few people. Crazy rich Mr. Musk is one example. He may not be able to achieve it, but maybe all we need is a few other Musks in the next generations and suddenly we'll be in other planets. The Fermi Paradox discussion is fascinating.
  - AndyPa32 6y ago
    > Our current gas emissions would disagree. While at first it might seem that Mars or any other planet is the solution to our environmental problem, the easiest solution to the problem would be fixing this planet. Colonizing Mars would take up so many resources that fixing Earth might be more cost-effective.
    - psychoslave 6y ago
      This is not Earth that needs to be fixed, it's human behavior. Teraformation and space conquest are fassinating topics, but "fixing our behavior to avoid to fuck up the only accessible viable environment we have" is far from deserving only a mere "might be more cost-effective".
    - dyingkneepad 6y ago
      But way less fun :) Or we could, you know, just transfer our consciousness to machines that can easily survive Mars and other environments and start our colonization after declaring ourselves to be Homo-sapiens-machina.

beamatronic 6y ago

That’s why the best thing any species can do for the other species is to leave signs that we were once here.

buran77 6y ago
We still need to leave a heck of a collection. On a living, evolving planet if all civilizations are gone the signs get wiped out pretty fast in geological time (geology, weather), and in space the signs are usually traveling in the emptiness with little chances of being spotted. The best probes will eventually fail and will just add to the countless objects floating never to encounter anything. I know it sounds depressing but I keep getting reminded of this [0] when thinking of loneliness in the universe. It's the most apt description I came across in recent memory. [0] https://www.theoatmeal.com/comics/oracle https://www.theoatmeal.com/comics/oracle
- njarboe 6y ago
  On the other hand, large objects made by us on the Moon could last for 100's of millions of years. Especially if the object was designed to last that long.
- beamatronic 6y ago
  I like the comic. It's almost like all intelligent life in the universe was put into escape-proof cages. We need to rage against this! Do it for all the others who can't.

theandrewbailey 6y ago

I remember reading somewhere that due to the differing pace of evolution and technology advancements, any intelligent living aliens we meet are almost certainly going to be gods or cavemen. I can't find the reference.

krapp 6y ago
It's from Arthur C. Clarke: "If one considers the millions of years of pre-history, and the rapid technological advancement occurring now, if you apply that to a hypothetical alien race, one can figure the probabilities of how advanced the explorers will find them. The conclusion is we will find apes or angels, but not humans." [0]http://www.projectrho.com/public_html/rocket/alientech.php http://www.projectrho.com/public_html/rocket/alientech.php
- kfarr 6y ago
  I like that quote but lately feeling like advanced tech doesn't necessarily mean angelic
  - krapp 6y ago
    Angelic doesn't imply good, just being sufficiently advanced enough to seem like magic (to use another Clarke quote.) Demons are technically angels after all.
    - zabardasth 6y ago
      > And she took on another heart—no longer minded toward earthly things—but ecstatically in the angelic dialect, sending up a hymn to God in accord with the style of the angels. And as she spoke ecstatically, she allowed “The Spirit” to be on her garment. It seems that speaking to one would be quite a terrifying experience, especially if one were speaking in tongues.
      - krapp 6y ago
        When angels are described in the Bible, it's often in strange and abstract terms, beings with multiple faces, legs made of burning bronze, eyes where eyes shouldn't be, etc. As if the writer was having difficulty comprehending what they were seeing,much less finding language for it. And the first thing angels do when they encounter humans is tell them not to be afraid, because of course the logical and proper reaction to skyscraper-sized interlocking, burning, eye-covered wheels with multi-faced, multi-winged beings in the middle is bowel evacuating terror. And of course, many of Lovecraft's eldritch horrors were simply aliens that were so alien that the mere sight of them broke human minds, and that were no more concerned for humanity than humanity is for a particular anthill. That's probably what an actual encounter with an alien is going to be like for us. We'll try to understand why a living infinite-dimensional hypersphere made of flesh made of time whose eyes are our eyes all at once just showed up and "unfolded" our sun into a non-Euclidean shape we can't even describe mathematically without being driven slowly to madness, while it won't even know we were there.

anonAndOn 6y ago

While interstellar travel would be impossible using conventional thrust in a straight line, could you overcome the distance by bending space time?[0] [0]https://www.nasa.gov/centers/glenn/technology/warp/gravstat.html https://www.nasa.gov/centers/glenn/technology/warp/gravstat....

ben_w 6y ago
Going fast in a straight line with conventional rockets is achievable, just not very timely. Bending spacetime enough to make a difference — even just to the time taken between here and Alpha Centauri — is beyond any known mechanism humans could build, even in principle, using the total resources of our entire solar system. (Using unknown mechanisms: perhaps, but they’re unknown)
- skissane 6y ago
  > Going fast in a straight line with conventional rockets is achievable, just not very timely. A constant-acceleration spacecraft could reach the opposite side of the galaxy in 24 years ship time. (That'd be over 100,000 years of Earth time, however.) Conventional chemical propulsion don't have high enough impulse to do that. Possibly some kind of nuclear or matter-antimatter propulsion could?
  - ben_w 6y ago
    Everything would run out of fuel over that distance if you were constantly accelerating ahead [0], but you don’t need to constantly accelerate in space. [0] spinning is accelerating, and you can do that forever, but it won’t help you get anywhere
  - avhon1 6y ago
    Atomic Rockets has some good info on this. > When it comes to [high thrust, high specific impulse] propulsion systems we might actually be able to build in the near future, the list includes Orion drives, Zubrin's nuclear salt water rocket, and maybe Medusa. There have been many studied variations of Orion. Atomic Rockets cites hypothetical Isp between 3,000 and 12,000 seconds. Vehicles with delta-V of up to 100,000 m/s have been proposed. These could definitely be built, and would definitely work, but would require constructing, co-locating, launching, and detonating thousands of 5- to 15-kiloton nuclear explosives. http://www.projectrho.com/public_html/rocket/enginelist3.php#boomboom http://www.projectrho.com/public_html/rocket/enginelist3.php... Medusa is basically Orion crossed with the image of a sailor blowing into their own sails. A huge parachute is deployed in front of the spaceship, and the nuclear explosives are detonated between it and the bow of the spaceship. The parachute can capture more of the explosive output than Orion's pusher plate can, it weighs less (because all of its members are in tension), and it can use its rigging's elastic properties to dampen the intermittent thrust, as opposed to Orion's (heavier) hydraulic dampers. The proposal study for Medusa (which assumed thirty 25-kg explosives) came up with an Isp of 106,220 seconds, and a delta-V of 4775 m/s. http://www.projectrho.com/public_html/rocket/enginelist3.php#medusa http://www.projectrho.com/public_html/rocket/enginelist3.php... The Nuclear Salt Water Rocket assumes plausible (but completely untested, so maybe impossible) continuous nuclear fission in a stream of uranium-salt-y water being sprayed into the combustion chamber. Assuming that this can be made to not blow itself up, 20%-enriched salt nets a theoretical Isp of ~7,000 seconds, and 90%-(weapons-grade) enriched fuel, with somewhat more optimistic efficiency assumptions, has a theoretical Isp of ~400,000 seconds and a delta-V of 10,000,000 m/s. http://www.projectrho.com/public_html/rocket/enginelist2.php#nswr http://www.projectrho.com/public_html/rocket/enginelist2.php... There are also lots of other currently-less-plausible proposals for high-power high-efficiency rockets. (Many of them assume things like efficient proton-proton fusion, which might be possible, but we have no idea how to do it.) Atomic Rockets is a great website for reading about these. My takeaway is that it's almost certainly possible to build spaceships that can travel at >0.01c, but it would take a great deal of resources organized by a society that is more trusting and responsible than we are now. After all, any vehicle with that kind of power is also an equally powerful weapon.

dylan604 6y ago

> Humans have been civilized for only some tens of thousands of years, That's giving humans a lot of credit. Civility has been regressing. I would be embarrassed for another civilization to find us now. Sure, we may have more technology and scientific understanding, but how we treat one another needs another world than civil.

sbelskie 6y ago
I don’t think civility has a lot to with civilization in the anthropological sense of the word.
- dylan604 6y ago
  "...first use in English is attributed to Adam Ferguson, who in his 1767 Essay on the History of Civil Society wrote, "Not only the individual advances from infancy to manhood but the species itself from rudeness to civilisation".[14] The word was therefore opposed to barbarism or rudeness, in the active pursuit of progress characteristic of the Age of Enlightenment." [0] [0]https://en.wikipedia.org/wiki/Civilization https://en.wikipedia.org/wiki/Civilization
  - sbelskie 6y ago
    “... in the anthropological sense of the word.” -me, just recently. If you are wondering where we might find a definition matching that sense, try the first sentence of the article you linked: “A civilization (or civilisation) is any complex society characterized by urban development, social stratification, a form of government and symbolic systems of communication such as writing.”