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| ▲ | xyzsparetimexyz 16 minutes ago | parent | next [-] | | Yes but none of them are especially pleasant. The least unpleasant way would be some kind of photonic rocket as it gives you the highest possible exit velocity and thus efficiency. Matter - antimatter annihilation produces photons that can be used for this. Antimatter collection and storage is an issue, engine and ship design is an issue, radiation is an issue, in space construction is an issue. But plausible? Sure, I guess. The ISVs from the Avatar movies of all things are the closest to what this would look like. | |
| ▲ | unrented7977 4 hours ago | parent | prev | next [-] | | The answer is actually yes if you're willing to wait. Interstellar travel is not impossible, no matter what anyone tells you. We know how, it's just wildly impractical. We've barely even left our own planet, and we've managed to throw a few chunks of metal out of our solar system so far. We lack the industrial capacity to build an interstellar ship, we do not lack the physics. | | |
| ▲ | stouset 3 hours ago | parent | next [-] | | There’s a huge asterisk here. IIRC, it is possible to get anywhere in the observable universe in one human lifetime assuming 1g of constant acceleration. This does not permit you to slow down and halt at your target, which greatly increases travel times. It is also effectively a one-way ticket for anything other than objects in our immediate stellar neighborhood. If you turned around and returned to Earth after getting to an object 1,000ly away—still well within our own arm of the galaxy—at least 2,000 years will have passed on Earth. It’s probable that no civilization you know of would still exist, nor would anyone be able to understand your language. This isn’t even beginning to address the problem of running into stray atoms at 99.99…% of the speed of light. Or god forbid a handful of stray molecules. We also haven’t discussed the real elephant in the room which is the sheer amount of energy required to accelerate a human and human life support systems at 1g for several decades. | | |
| ▲ | WalterBright an hour ago | parent | next [-] | | What to send is DNA along with some sort of robot that can grow it into a man upon arrival. | | |
| ▲ | dTal an hour ago | parent [-] | | Maybe better to start with a woman... | | |
| ▲ | shevy-java 12 minutes ago | parent [-] | | Not necessary. A cell (with a nucleus) has all the DNA required. You just need to have a viable system to build up a human from it. I think right now this is not possible, but this will be solved eventually. The question is, though: do future humans really want to do that? |
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| ▲ | AnimalMuppet 36 minutes ago | parent | prev | next [-] | | > nor would anyone be able to understand your language. Greek and Latin are still understood. I don't know if the Chinese spoken today resembles Chinese from 2000 years ago, but maybe some of the written language would be understandable. Both Hebrew and Tamil are comprehensible that far back, and farther. Arabic goes nearly that far back. Of course, that's six languages out of... how many do we speak? | | |
| ▲ | ben_w 17 minutes ago | parent [-] | | > Greek and Latin are still understood. Nerds specifically kept the archaic forms alive, but they'd also tell you that Latin and ancient Greek were not static for their whole existence (Attic != Homeric != Koine), and modern Greek is somewhat different from what is taught as "ancient" Greek. Treat Latin and (ancient) Greek like you would Quenya or Esperanto. If this were to happen with English, I'd expect us to keep Chaucer, Shakespeare, and enough to understand Victorian literature, but it's anyone's guess if modern English would survive at all. Arabic… kinda? It has an international standard form, but from what I've been told the language also comes with local dialects which can be difficult to mutually comprehend (though this is also the same with English just by going from central London to Sheffield). |
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| ▲ | tuveson an hour ago | parent | prev | next [-] | | > IIRC, it is possible to get anywhere in the observable universe in one human lifetime assuming 1g of constant acceleration. Huh? You can’t go faster than light speed, and the observable universe is way larger than ~100 light years. | | |
| ▲ | p_l 39 minutes ago | parent | next [-] | | Time experienced will be slowed down for the person in spaceship as you near lightspeed | |
| ▲ | pacman128 an hour ago | parent | prev [-] | | This is using the fact that at 1g acceleration, one will quickly approach the speed of light relative to its starting rest frame and time dilation will give the astronaut a _very long_ life relative to that frame. |
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| ▲ | Scarblac 3 hours ago | parent | prev [-] | | Also, how much fuel do you need to bring along to accelerate a human and life support system and the whole craft including fuel, for a lifetime? Is it larger than a planet? | | |
| ▲ | loudmax 3 hours ago | parent | next [-] | | Since we're already in the realm of far out engineering, you could get the energy from a laser beam from a source orbiting the sun. Your spaceship would have some kind of array to capture the energy beam. This gives you energy, but I'm not sure how to turn that into velocity. Presumably you'd want some kind of ion beam emitter on board to propel your craft forward. Halfway through the journey, you'd turn the ion beam around to decelerate as you approach your destination. In the Arthur C Clarke novel Songs of Distant Earth, spacecraft pushed huge blocks of ice ahead of them to absorb stray interstellar dust. | | |
| ▲ | stouset 2 hours ago | parent | next [-] | | As you get going further and faster, this energy redshifts further and further making it less and less useful. Also there’s of course the problem of focusing a laser with that amount of energy tightly enough on an object increasingly far away. | | |
| ▲ | iso1631 an hour ago | parent [-] | | And crucially ensuring that beam continues to run for billions of years. a few decades may pass for you, but not for the laser that's pushing you |
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| ▲ | m4rtink 3 hours ago | parent | prev | next [-] | | So there is also the idea of a ramjet that uses interstellar hydrogen as fuel for fusion, which provides energy & propulsion: https://en.wikipedia.org/wiki/Bussard_ramjet Some recent findings do give it lower feasibility though. | |
| ▲ | __MatrixMan__ 3 hours ago | parent | prev [-] | | Another option is to visit as many massive objects as possible on the way there, doing gravitational slingshots until you're half way, and then gravitational brakes on the approach. Of course now you're taking detours, but since certain amounts of fuel make the trip impossible, any workaround at all is an improvement. What's an extra few thousand years between friends? | | |
| ▲ | stouset 2 hours ago | parent | next [-] | | First, what “many objects along the way”? There are basically none. To do this requires many detours that significantly increase the distance you’re having to travel. Second, the faster you’re going, the less useful a gravitational slingshot is because you spend less time in the object’s gravity well. It’s a fun and useful trick within our solar system, but I don’t think the physics plays out well for interstellar travel. | | |
| ▲ | __MatrixMan__ an hour ago | parent [-] | | Stars is what I meant. Although upon further thought I think you're right. I guess the intervening stars are unlikely to be moving at helpful velocities for such a game of pinball, metric expansion being what it is. |
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| ▲ | m4rtink 2 hours ago | parent | prev [-] | | Slingshots require very specific conditions and configurations of orbiting bodies that won't really work in deep space - all the Kuiper Belt/Oort Cloud bodiees are far too small and too far away to be usable. But assume for example that you don't care about how long it is going to take (you are an immortal cyborg, an upload living in the computer or a popsicle in hibernation & the AI is driving. Then you can just "island hop" between Kuiper Belt/Oort Cloud objects, never gaining any high % of the speed of light but always having the next body in your sights, not farther than a few decades or a couple hundred years of flight at most. You reach the body, refuel, repair, maybe upgrade and then off you go, to the next one. And eventually, you might be at you destination, with a fully fueled and repaired ship. It might just take like 20000 years for start to finish, but hey, you can use it for something productive like learning to play Go or something. :) | | |
| ▲ | __MatrixMan__ 44 minutes ago | parent [-] | | You're right, I overlooked some important slingshot requirements. As for the longevity, I figure the ship can build a facility for growing settlers when it arrives. With no humans on board it can sustain heavier accelerations. |
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| ▲ | m4rtink 3 hours ago | parent | prev | next [-] | | Actually, even something as primitive as a NSWR (https://en.wikipedia.org/wiki/Nuclear_salt-water_rocket) can reach a good percentage of the speed of light after basically processing a comet for fuel. From the Wikipedia article: "The design and calculations discussed above are using 20%-enriched uranium salts. However, it would be plausible to use another design which could achieve much higher exhaust velocities (4,725 km/s) and use a 30,000-tonne ice comet along with 7,500 tonnes of highly enriched uranium salts to propel a 300-tonne spacecraft up to 7.62% of the speed of light and potentially arrive at Alpha Centauri after a 60-year journey." Sure, not 99% the speed of light or continuous 1 g acceleration but IMHO good enough for an oversized nuclear squirt gun. | | |
| ▲ | stouset 2 hours ago | parent | next [-] | | Still, this is many, many orders of magnitude short of what’s being discussed. Essentially the forefront of technology could get us to just barely speed past our nearest neighbor in one human lifespan. | | |
| ▲ | saalweachter an hour ago | parent [-] | | That's why we need to find a globular cluster with metal-rich planets, and take a generation ship over there. Sure, a thousand generations will live and die along the way, but once we get over there, you've got stars every 0.1 ly or so, and with very plausible future tech, you could navigate between them in a few years. You could set up a proper starfaring, interplanetary civilization, with tradeships either going back and forth between two neighboring systems, or winding on long, never-repeating routes, visiting a dozen or so star systems in a human life. (Most globular clusters appear to be old and metal-poor, and we haven't found a lot of planets there, and this only works if you find a globular cluster where ~every star can support a colony.) |
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| ▲ | metalliqaz an hour ago | parent | prev [-] | | Imagine such a complex machine working without fail for 60 years. It's just not plausible in my view. |
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| ▲ | __MatrixMan__ 3 hours ago | parent | prev | next [-] | | Less if we just send some eggs and sperm and spin up a human on arrival. We can construct a larger life support system out of things we find at the destination. Or better yet, send some cancer cells so they can replicate during the journey, then switch from cancer mode to gamete mode for the final generation. That way they're fresh when you need them. You're gonna want DNA repair happening continuously, rather than all at once upon a thaw. | |
| ▲ | stouset 3 hours ago | parent | prev [-] | | Yeah, I added that I think around the time you replied :) |
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| ▲ | nonethewiser 3 hours ago | parent | prev | next [-] | | >Interstellar travel is not impossible, no matter what anyone tells you. We know how, it's just wildly impractical. This was provocative and intriguing so I looked into it and this is my understanding of some of the options (theoretically). First, "interstellar" means between stars and the closes star is 4.2465 light years away (Proxima Centauri in Alpha Centauri star system) so I used that. c=speed of light - Chemical (Voyager), ~0.006% c: ~75,000 years
- Nuclear pulse (Orion), ~3-10% c: ~40-130 years
- Fusion (Daedalus), ~12% c, flyby: ~35 years
- Laser sail (Starshot), ~20% c, flyby: ~21 years (gram-scale probes only)
- Antimatter, ~20-30% c stopping: ~14-21 years; ~50% c flyby: ~8-9 years
Nuclear pulse surprised me in particular. My understanding is you basically just detonate a bunch of nukes to propel yourself. There are legal hurdles not to mention fallout, but it sounds like the physics of simply getting there in 40+ years (not stopping, mind you) is possible with todays physics. That's pretty amazing and I had no idea. | | |
| ▲ | m4rtink 3 hours ago | parent [-] | | Yeah - and the mass fraction is also very good for Orion. You can basically build your ship from boiler plate (and you kinda have to) in a shipyard, no need for fragile ultra light stuff. Also past LEO you don't really have issues with fallout. So the only real hurdle is securing the supply of couple thousand nuclear bombs for the trip. But if you told people in 1903 that you can build a plane that will get 850 people 14000 km but you need 250 tons of kerosene to fuel it, they would also think you are insane (e.g. an Airbus A380). But over time, even with Orion, people will just get used to it. :) |
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| ▲ | TheOtherHobbes an hour ago | parent | prev | next [-] | | We also lack the biological knowledge to build stable closed ecosystems that last for years with minimal degradation of essential elements and processing systems, the engineering knowledge to build complex machines that last for years without any significant failures while being ablated by space dust and occasional rocks, and the political and psychological knowledge to keep a crew sane, focused, and functional. Apart from that - solved problem. | | |
| ▲ | thangalin an hour ago | parent | next [-] | | > to build stable closed ecosystems Sealed terrariums? Unless you mean something more complex than plants, soil, sunlight, and water? https://laidbackgardener.blog/2019/10/14/the-worlds-second-o... "That means it has been growing inside its bottle with no additional air, water or fertilizer for 47 years." | | | |
| ▲ | PaulHoule an hour ago | parent | prev [-] | | ... and once you get to the destination you have to build your whole industrial infrastructure from a tiny seed. It's bad enough to do on Mars (or an asteroid or other solar system environment) where you can get spare parts sent over in a few years and ask ground control for answers to problems, have them simulate things on Earth or in cislunar space and put a lot of engineers on it. The more I think about it the worse it seems in our solar system -- but interstellar travelers are truly on their own. |
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| ▲ | stymaar 3 hours ago | parent | prev [-] | | We don't lack the industrial capacity either, we mostly lack a good reason to spend these resources in that direction. And IMHO that's the main explanation for the Fermi paradox: we don't see aliens everywhere because they don't have a good reason to colonize other planets than their own either. | | |
| ▲ | 7373737373 3 hours ago | parent | next [-] | | Would that not also imply that improvements in ease of access to space, increase of energy production and -price reduction all level off before it becomes easy and affordable enough that mere curiosity would suffice to make it possible, for ALL civilizations? | | |
| ▲ | stymaar 3 hours ago | parent [-] | | Due to science fiction people tend to forget how miserable life in space is. Nobody would chose to sacrifice themselves and their descendants (because that's what such an expedition is about), for mere curiosity. And nobody would fund an expedition that will not reach destination before multiple hundreds of years, even if the said expedition doesn't consume the entire industrial output of a major nation. Space is BIG. |
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| ▲ | mytailorisrich 3 hours ago | parent | prev | next [-] | | We do lack the technological capacity. Travelling to another star would require a fully self-contained spaceship with energy, life support, food, medical facilities, even production facilities able to function for centuries or millenia. We simply don't know how to do that. | | |
| ▲ | stymaar 2 hours ago | parent [-] | | Yes, we don't know how to do that, but we don't know how to build hundreds of aircraft carriers per year right now either, yes the US has done the later in WW2 and would probably be able to do it again should it be needed in an existential war. With a sustained nationwide effort comparable to WW2 we could most likely send a spaceship out if the solar system in ten years or so. But why would anyone do that? | | |
| ▲ | mytailorisrich 2 hours ago | parent [-] | | Building hundreds of aircraft carriers a year is an issue of scale, so of money and allocation of resources (assuming we have the manpower). But what I mentioned is more profoundly that we simply don't know how to even build one. It's knowledge and technology which are lacking. Typical these things fall into one, two, many. Can you build one, two, many? These are very different propositions. One means you know understand how to do it, mostly. Two means you can repeat it, so you do understand it, it wasn't a fluke. Many is scaling the process. | | |
| ▲ | stymaar an hour ago | parent [-] | | Scaling is a technology of its own (and it's often the hardest part). |
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| ▲ | iso1631 an hour ago | parent | prev [-] | | Once it becomes cheap enough then religious or similar cults will do it, and the cost of doing isn't a great deal more than colonising the solar system where are are economic benefits. That assumes reaching 5 light years in say 50 years However once it's done a few times, then it can't be stopped. If you're going at say 1/1000th of the speed of light (50 years to travel, 450 years to settle and build the next wave is 1% the speed of light) then your successor species will have colonised the galaxy in 100 million years, and we know that hasn't happened. |
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| ▲ | m4rtink 3 hours ago | parent | prev | next [-] | | Well, even if we could not reach such a planet in a reasonable time yet, a research like this could still be very useful for many reasons. It could help us learn how our habitable environment works and operates, it might be applicable for terraforming or habitat construction. There is also a non-zero chance of some sort of life, possibly intelligent developing in such an environment (as proven by our sample size of 1). That life can be active at the moment (from our PoV - light speed and all) or was active in the past, so we should look for bio signatures or even signs of mega scale engineering. | |
| ▲ | theptip 3 hours ago | parent | prev | next [-] | | Yes, easy assuming multi-generational arcologies. There are plenty of designs that get you to 0.1c or above if you are Kardashev 2, things like light sails powered from the Dyson sphere. Nothing plausible for anyone living today AFAIK. | |
| ▲ | cdelsolar 3 hours ago | parent | prev | next [-] | | It wouldn’t be that fun to live on one. The article says picture paradise, but we’re talking about potentially 1.5-2g with a dense atmosphere; we’d feel terrible all the time. Also whatever biology is in that planet is probably not compatible with us; we likely wouldn’t be able to eat it. Finally once you land, you’re screwed and stuck there. Traditional chemical propellants barely work for our planet, we’d need new ways of taking off for higher escape velocities. | | | |
| ▲ | imzadi 4 hours ago | parent | prev | next [-] | | Generation ships with plasma sails, probably. | | |
| ▲ | neaden 2 hours ago | parent | next [-] | | But we don't know how to make a self sustaining fully sealed environment on Earth, let alone in space. | |
| ▲ | bilbo0s 4 hours ago | parent | prev [-] | | And what happens when they encounter a GRB? Interstellar travel is not a propulsion problem. It's a space travel problem. The medium itself, is the vast majority of the problem. | | |
| ▲ | Tuna-Fish 16 minutes ago | parent | next [-] | | Just die. That's not actually a problem, because dangerous GRBs are simply not that common. Earth gets hit by one every day, but, that includes GRBs from very distant galaxies that are so weak when they hit us that they would not be any danger even to a completely unshielded person in orbit. GRBs of sufficient power to be an actual threat to people in a tin can is one/millions of years, at which point it's a propulsion problem again. Yes, there are lots of things that could kill the ship on route. No, none of those are actually a significant problem compared to the basic "how to get there before everything breaks down from internal issues". | |
| ▲ | unrented7977 4 hours ago | parent | prev | next [-] | | Space is, and I must emphasize this in the strongest possible terms, really FUCKING BIG and dangerous GRBs tend to be tightly focused given the inverse square law. It's highly unlikely that a ship gets hit by a GRB. On the other hand, general radiation gets worse the faster you go, so you need shielding either way. All you have to do is line the walls of your ship with a shit ton of water, which can be mined in space. | | |
| ▲ | arbuge 10 minutes ago | parent | next [-] | | > All you have to do is line the walls of your ship with a shit ton of water, which can be mined in space. But that water needs to be encased in something, and your problem now becomes protecting the encasement. | |
| ▲ | zdragnar 3 hours ago | parent | prev | next [-] | | I'm reminded of the joke that the most dangerous thing in the ocean is all the water. We don't have fuel sources that can run long enough for the trip, and deep space won't have enough solar radiation. We would need reliable mining spots along the way to replace metals made brittle by exposure or punctured by micro asteroids. Even travelling at 1% the speed of light, stray hydrogen atoms become a problem. Not counting acceleration or deceleration time, that would be over 400 years just to get to the nearest star, let alone one with a habitable planet. | | |
| ▲ | m4rtink 3 hours ago | parent [-] | | In all current realistic plans the idea is to accelerate once and decelerate (if needed) at the destination. So not really doable to stop by on the way, unless you are going really slow - or its a part of the Voyage (e.g. multi millennia round trip where you replenish in every suitable star system along the way) provided your ship can handle the acceleration (could be assisted by built infra) and deceleration of a given "hop". |
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| ▲ | cdelsolar 4 hours ago | parent | prev [-] | | Can you really mine water in interstellar space, how? there’s not that many asteroids just floating out there, I think. | | |
| ▲ | GolfPopper 3 hours ago | parent [-] | | Maybe the previous poster was referring to the Kuiper Belt and/or the Oort Cloud? There's certainly plenty of water ice out there, with no particularly deep gravity wells to worry about. Collecting it while usefully en route to another star system seems like it would be tricky from a delta-v perspective, but maybe the solution is to: 1) build a small worldship from an appropriate asteroid
2) fill your internal ocean in the outer solar system over the course of a generation or three
3) dive back down the gravity well for a gravitational assist from the Sun as you head to your interstellar destination
4) en route, slowly use part of your ocean as propellant, while living inside the rest of it as shielding | | |
| ▲ | m4rtink 3 hours ago | parent [-] | | There is a nice concept I've read I think on either Orions Arm or Project RHO about basically settling the Kuiper Belt and the Oort Cloud. It would not really be about primarily traveling anywhere, just people settling this are with its immense resources over many generations, until possibly the ones on the furthest reaches would be able to make the jump to the next systems Oort cloud & slowly settling it down the gravity well, maybe even reaching the inner system eventually, provided something so tiny and sweltering would be of interest for them by that point. ;-) IMHO this is actually much closer to how humans spread along the Earths surface. It was no like someone just get up and walked from Afrika to Australia. The various human group just expanded their habitat over time until they spread all over the place over many thousands of years and this would be similar. |
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| ▲ | indoordin0saur 2 hours ago | parent | prev | next [-] | | Destructive GRBs are actually so rare that I'd seriously bet on our spaceship getting attacked by a belligerent alien vessel before thinking the mission gets taken out by a GRB. | |
| ▲ | mrnotcrazy 4 hours ago | parent | prev | next [-] | | What is a GRB? | | |
| ▲ | marricks 3 hours ago | parent | next [-] | | Gamma Ray Burst https://en.wikipedia.org/wiki/Gamma-ray_burst : > (GRBs) are extremely energetic events occurring in distant galaxies that represent the brightest and most powerful class of explosion in the Universe. > The sources of most GRB are billions of light years away from Earth, implying that the explosions are both extremely energetic (a typical burst releases as much energy in a few seconds as the Sun will in its entire 10-billion-year lifetime)[11] and extremely rare (a few per galaxy per million years). > All in all, a GRB within a few kiloparsecs, with its energy directed towards Earth, will mostly damage life by raising the UV levels during the burst itself and for a few years thereafter. I'm guessing without an atmosphere protecting a ship it'd be a bit worse? But it's like winning a very bad lottery to get hit by one. I guess if you're traveling thousands of years in deep sleep odds get higher? | | |
| ▲ | iso1631 an hour ago | parent [-] | | Sending one ship will probably fail, but if you can send one, you can send 1000, and they aren't all going to be wiped out. |
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| ▲ | philk10 3 hours ago | parent | prev [-] | | Gamma-ray burst |
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| ▲ | marcusverus 4 hours ago | parent | prev [-] | | The solution to this problem is straightforward, isn't it? Just add mass. Propulsion is the technological bottleneck. |
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| ▲ | ajuc an hour ago | parent | prev | next [-] | | Sure, just not the same human that launched from Earth. The Cologne Cathedral in Germany was started in 1248 and finished in 1880. That's 632 years. | |
| ▲ | Jtarii 3 hours ago | parent | prev | next [-] | | We are at least 1000 years away from being anywhere close to this. | | |
| ▲ | indoordin0saur 2 hours ago | parent [-] | | Whenever people say we are "x years away from this technology" I find it incredibly silly. You have no idea if in 2028 AGI is going to deliver some way to efficiently create and store antimatter. Nor do you know if (assuming AGI never comes) there will be some intellectual flourishing of humanity in a few decades. Nor do you know if we're on the precipice of a multi-millenia dark age. |
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| ▲ | bilbo0s 4 hours ago | parent | prev [-] | | >given what we know about physics at the present? No. My hypothesis has always been, hey, have enough kids out there, and sooner or later, they'll learn enough about the physical sciences to at least explore far away worlds. (If not go there in person.) But yeah, expecting we can get there with what we currently know is a bit naive. We need to, <gasp>, horror of horrors, fund more research. | | |
| ▲ | bluGill 3 hours ago | parent [-] | | Space is really big. We might be able to get a probe someplace, but can't get data back. We don't even have the ability to detect a civilization as advanced as us at the nearest star (only 4 light years away, but probably can't support life as we know it) if they put all their resources into sending us a message, and we spend all our resources to look at the right moment. There are laws of radio propagation that mean I doubt we ever will. In turn this means a probe needs to get there, and then come back. That is a lot of energy... I can't say it is impossible, but it is highly unlikely the laws of physics will ever give us a loop hole big enough to pull this off. | | |
| ▲ | m4rtink 2 hours ago | parent | next [-] | | I don't think there any physical limitation for communicating with a probe at a couple light years at least. Project Daedalus had this all modeled and specified back in the 1970s (https://en.wikipedia.org/wiki/Project_Daedalus), using a 40 meter directional antenna on the probe. | |
| ▲ | m4rtink 2 hours ago | parent | prev [-] | | Not to mention sufficiently big megascale engineering not to mention some of the more crazy kinds of propulsion (NSWR, antimatter, etc.) should be perfectly visible with current technology over 4 light years and possibly much farther away. |
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