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Space Transportation

The Three Possible Classes of Interstellar Travel (forbes.com) 330

An anonymous reader writes: The stars call to us through the ages, with each and every one holding the promise of a future for humanity beyond Earth. For generations, this was a mere dream, as our technology allowed us to neither know what worlds might lie beyond our own Solar System or to reach beyond our planet. But time and development has changed both of those things significantly. Now, when we look to the stars, we know that potentially habitable worlds lurk throughout our galaxy, and our spaceflight capabilities can bring us there. But so far, it would only be a very long, lonely, one-way trip. This isn't necessarily going to be the case forever, though, as physically feasible technology could get humans to another star within a single lifetime, and potentially groundbreaking technology might make the journey almost instantaneous.
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The Three Possible Classes of Interstellar Travel

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  • by Anonymous Coward on Saturday January 02, 2016 @04:47PM (#51227743)
    here is a working link thats not thru forbes. http://scienceblogs.com/starts... [scienceblogs.com]
  • Physically feasible? (Score:2, Informative)

    by Anonymous Coward

    Let's say a single lifetime is 100 years. Well above average, but whatever.
    The nearest star to Sol is a little over 4 light years away.
    So you have to go over 4% of c to succeed. Good luck with that!

    • by KiloByte ( 825081 ) on Saturday January 02, 2016 @05:58PM (#51228019)

      Disregarding science-fiction babble like in this article, the fastest we can get to Proxima Centauri is 80k years assuming no fundamental breakthrough, or 100 years with ultimately advanced technology that's not known to be impossible with our current knowledge of physics.

      Writers of such articles tend to forget that every gram of fuel needs to be accelerated by previous stages, and even worse, all the fuel needed for deceleration must be first accelerated all the way then decelerated partway. This puts a hard cap even if you magically got 100% efficiency.

      But fortunately, such writers are also forgetting that physics isn't the only technology field that advances. I'd expect that both stopping aging and sentient AI are no more than 100-200 years away. Just don't forget to take playing cards with you to spend time during than 80k years long trip.

      • by dryeo ( 100693 )

        An Orion might be able to get there in a hundred years and should be doable with current technology.
        Actually wiki says Dyson had a design almost doable with '60's tech that took 133 years to Alpha Centuari, longer if you wanted to stop at the end. Ship was only 100,000 tons + 300,000 tons of fuel (100 metres diameter) and only achieved 3.3% light speed with a cost of 10% US yearly GDP.
        More realistic design (10,000,000 tons empty, 40,000,000 tons fueled) took 10 times longer and cost a full year of US GDP.
        Th

    • Let's say a single lifetime is 100 years. Well above average, but whatever.
      The nearest star to Sol is a little over 4 light years away.
      So you have to go over 4% of c to succeed. Good luck with that!

      While we are working on that warp engine, we need to also be working even harder on something that is more important -- being able to identify planets that are at least marginally inhabitable.

      While astronomer brag that they have now identified hundreds of extra-solar planets, they still know absolutely nothing about them. And a few planets which have been 'discovered' in recent years have turned out to not actually exist.

    • That someone is speculating about this topic at all is akin to the Knights of The Crusades speculating how warfare will be waged in 2016...
    • by C0R1D4N ( 970153 )
      I think it more likely that we will be able to extend lifespans to thousands or hundreds of thousands of years through cybernetics/cloning/brain transplants long before we can achieve near-light speeds.
  • by Grishnakh ( 216268 ) on Saturday January 02, 2016 @04:51PM (#51227759)

    Only a blank page.

    No, I'm not going to enable Javascript on two dozen sites to see this shit. Post a real link or STFU.

    • I see the same thing. It just redirects to some sort of "welcome to forbes" site.. Not sure if they want you to pay or what.

      Forbes' site is a hot mess. Its even worse on mobile.

      This seems to be a copy of the same article without Forbe's garbage:
        http://scienceblogs.com/starts... [scienceblogs.com]

      • Ok, its NOT the full article, and I can't seem to find it from a non-Forbes' site... Ugh.

  • by wjcofkc ( 964165 ) on Saturday January 02, 2016 @04:53PM (#51227761)
    This poses some interesting possibilities. Let us say for example that we do find human-habitable places in the galaxy, but they are very far away so we send generation ships. Now let's say that 150 years into a 300 year journey some seriously fast FTL is invented on Earth (I more than suspect it is not possible though, hope I'm wrong). They now just have a few years journey. Would we send a ship to pickup the people on the slow boat? It would be kinda nuts to finally get there and find humans have been there for shy of 150 years. Then again if it's wormhole technology we would probably have to drag half of the device to the other planet to begin with.
    • I wouldn't worry about the en-route slow boat. They may all be dead anyway so how would you know. Instead if spend the money on a legit welcome celebration for when/if they arrive.

    • by wjcofkc ( 964165 )
      I think I made a mistake... If the slow boat has been travelling at relativistic velocity, 150 on the ship would be pretty far in the future relative to time on Earth. Okay, that is making my head hurt. Is there anyone here who sees where I am going with that and could clarify?
      • If the FTL drive allowed (for simplicity's sake) instaneous travel to another planet (such that the "now" when you arrived would be the same "now" as when you left, in the [again for simplicity] exactly shared reference frame between Earth and the distant planet), then yeah, once the slow ship decelerated and got to the planet, more than 150 years would have passed (more than 300 for the total journey).

        Also note that a 300 year (for the crew) relativistic journey would cover a lot more than 300 light years

    • In one of Lem's books, the protagonist (Ijon Tichy [wikipedia.org]) picks up the Popov [wikipedia.org]'s first radio signal somewhere between stars.
      • Heinlein, Time for the Stars, the fast boat picks up people from the slow boat.

        • by dwywit ( 1109409 )

          Or there's Niven's idea of a fusion ramjet. Endless marginal acceleration, using enormous magnetic fields to funnel tenuous interstellar hydrogen into a usable density.

          Apart from having to carry a reserve, it's self-fuelling. Of course, shielding the cargo/passengers from the radiation would be an issue, but it's an idea worth pursuing, perhaps even modelling in software.

          • That was Robert Bussard's idea (same one who conceived the polywell)

            There are questions if drag can be overcome though

    • Or worse, in 150 years we discover that the planet that the generation ship is headed for is unsuitable for some reason.

      • by wjcofkc ( 964165 )
        Hmm. If the ship is unable to deviate or come back, would we try to get them a message that they are really screwed, or just let it go because there is no point in freaking them out?
    • by westlake ( 615356 ) on Saturday January 02, 2016 @07:09PM (#51228303)

      This poses some interesting possibilities...

      Sci-Fi writers have been looking at these paradoxes from the beginning.

      The short answer is that interstellar emigration implies that your back is against the wall. It is now or never kind of thing --- with a very good chance you will doing everything you can to conceal your true destination.

      Methuselah's Children [wikipedia.org] (1941, 1958)

      Rescue Party [wikipedia.org] (1946)

      Battlestar Galactica [wikipedia.org] (2004)

    • I strongly suggest you read Stephen Baxter's short story Mayflower II [goodreads.com]

      You'll enjoy it, I promise.

  • Even on a text of a wholly speculative nature (something that a piece like this would inevitably have to be), I would expect something more definite. The author simply fled from the difficult (and interesting) part. He didn't even come close to outlining the "constraints" mentioned on the first paragraph, as well as the 'physical feasibility' aspects referred to in the original post. As it stands, the article is wholly irrelevant. (Please spare me the "a la thundercats" thing. And the image from the double-
  • by Beck_Neard ( 3612467 ) on Saturday January 02, 2016 @04:56PM (#51227783)

    1. Generation ships
    2. Nuclear propulsion, antimatter propulsion
    3. Science fiction (warp drives, transporters, etc.)

    Anyway all of this seems moot to me. We can already freeze human beings for long periods of time. It's called 'embryo freezing' and it's commonly used.

    • You forgot the possibility of hibernation ships. If it is possible to slow the metabolism of humans to a very slow rate then it might be possible to reach distant systems.

      If we want to settle on a distant planet we are in for a challenge of optimizing the amount of people that can be transferred. Maybe one solution is to freeze semen and embryos and man the space ship with women. Someone calculated that the minimum number of individuals needed to ensure genetic stability is 1600, but I think that 2000 is pr

      • But if humankind shall prosper in the long run it's necessary. In 500 million years earth won't be habitable.

        In 500 million years, our descendants won't be human any more, so no big. The hard limit is in 5 billion years, when the sun goes red giant and fries the planet. But that's a looooong time.

      • I like how we're talking about sending 2000 people to another star system, when the most people we've ever had in space simultaneously is 13, and the total number of people who've even BEEN to space is 1/4th of the number we're talking about, and that is in all of human history.
        Hell, Its fun to think about how to send people across the stars, but when it comes right down to it, we are WAY short of the technology to even start.
        • The good thing about generation ships is that they are possible. Expensive, yes - they are firmly in the realm of megaproject, something that would take a politically unified earth and a good chunk of the GDP of all civilisation for a few decades. But that's just a logistics and engineering problem: They don't depend on any fundamental change in our understanding of the universe or inventions that might not even be allowed by the laws of physics.

          • No they are not. You used current tense there. We have no architecture that even approaches being able to withstand the stresses of that scale resisting the needed forces.
    • Class 1 also includes sending frozen people, etc., but the article doesn't put any more detail into it. It also doesn't include the fact that we don't have a clue how to build a long-term stable ecology that a generation ship or even a Mars colony would need.

      He also doesn't include Class 4 - Robots/AIs instead of canned meat humans. That's the most likely option, and building a drive that will ever get to another star is still in the "sufficiently advanced technology" category, not actually conventional t

    • Organic matter deteriorates in cryostasis. There is a limit on keeping human eggs in a freezer and still be viable. One of the issues is radiation damage accumulates, with no system to purge it as a living creature does.
      • This really depends how long you can keep it in stasis, how good your shielding is, and how many embryos you can take. Given good shielding and low enough temperatures, eukaryotic cells can probably be stored for at least a millenium or two with a feasible percentage of the cells surviving the journey. Beyond that, we simply don't know, but there are some ways to work around that. You could store germ line stem cells and periodically 'wake' them up to divide and repair their damage and then freeze them agai

    • ... is non-biological survival, as described in Arthur C. Clarke's Rendezvous with Rama. [wikipedia.org] (1973) Rama is also a reminder that you don't need true "artificial gravity" or even a "space drive" if you can build on the grandest of scales and don't particularly care how long the journey will take or that it will almost certainly be a one-way trip.
    • 1. Generation ships
      2. Nuclear propulsion, antimatter propulsion
      3. Science fiction (warp drives, transporters, etc.)

      Anyway all of this seems moot to me. We can already freeze human beings for long periods of time. It's called 'embryo freezing' and it's commonly used.

      You can freeze the embrios, but you still need a mother that will give birth to the babies. At the very least you need some kind of matrix.

  • by gijoel ( 628142 ) on Saturday January 02, 2016 @05:00PM (#51227799)
    So it looks like I won't be reading it. Such a shame.
    • Would you prefer everything be locked down behind paywalls? "Free" content has to be paid for somehow you know. I'd rather have adverts on sites than have to keep track of hundreds of subscriptions, each of which I'd only read a few articles on a couple times per month.

      • I'm not using an ad blocker, just NoScript and I cannot read Forbes.com content w/o allowing (probably unnecessary) Javascript on about two dozen third-party sites, which is unacceptable. Forbes should consider using fewer third-party references or perhaps only JS from their own domain.

        I don't have a problem with (preferably minimal, unobtrusive, un-annoying) advertising, but tons of crap Javascript is something else.

      • by wjcofkc ( 964165 )
        I agree. I don't ad block for that very reason.
  • by gavron ( 1300111 ) on Saturday January 02, 2016 @05:09PM (#51227837)

    First, the link goes to forbes.com which blocks any browser with an ad-blocker. http://fortune.com/2015/12/22/... [fortune.com]
    That's ironic and hamfisted, but particularly in light of Forbes own September 2015 article that says ad blockers won't hurt online adversiing. http://www.forbes.com/sites/ro... [forbes.com]

    Second, the summary of this "anonymous posting" says:

    The stars call to us through the ages, with each and every one holding the promise of a future for humanity beyond Earth

    No. They don't. Humans evolved to live here, on Planet Earth. Not on our own star, or on any other star, and humanity's future is right here where we have an entire planet we were built for... not on a foreign star.

    How CRAZY would we think it of MONKEYS who want to live underwater? We'd marvel at why happy jungle monkeys would leave a comfortable environment free of most predators and full of food to go somewhere hostile where they can't breathe, their temperature will decay, and without machine aids would soon die.

    That's no different than us claiming that other stars[sic] becon us to live there. No. There's great scientific exploration to be done, and we could even establish limited outposts where machines keep us alive despite the harsh vacuum and cold [or relative heat] of space. The ISS is a good example of one such outpost. However, there's no "interstellar colonialism" happening because the rest of the universe is inhospitable.

    Saturday... when an "anonymous" (friend of the editor?) posts something that makes no sense, and links to a site that's about as close to a paywall as you can get.

    Ehud

    • ...Humans evolved to live here, on Planet Earth. Not on our own star, or on any other star, and humanity's future is right here where we have an entire planet we were built for... not on a foreign star.

      I disagree. No matter how inhospitable, we will go there, and try to live there. My opinion is based on history. People migrated out of Africa, where they had evolved, into Eurpoe and Asia, which had relatively inhospitable climates. More recently, people have chosen to live at the South Pole, which is almost as desolate as the Moon.

      • "More recently, people have chosen to live at the South Pole, which is almost as desolate as the Moon."

        No-one has been optimistic enough to colonise near the pole. There are outposts there for scientific purposes, but they are not self-sustaining - they depend entirely on supplies from outside.

    • Re: (Score:2, Insightful)

      by Anonymous Coward

      Humans evolved to live here, on earth, sure. So what? Evolution is a constant process, by which an organism adapts itself to a particular enviroment. Sure, you don't see your average tree hopping monkeys make machines that let them live underwater, but do you think humans could've survived in arctic, or central european climate without clothes? By your logic humans should've stayed in Africa hunting whatever runs around there. Of course, space is an example of a far more harsh enviroment, but that's what ev

      • Humans evolved to live here, on earth, sure. So what? Evolution is a constant process, by which an organism adapts itself to a particular enviroment. Sure, you don't see your average tree hopping monkeys make machines that let them live underwater, but do you think humans could've survived in arctic, or central european climate without clothes? By your logic humans should've stayed in Africa hunting whatever runs around there. Of course, space is an example of a far more harsh enviroment, but that's what evolution is for. If it requires humans to create complicated machines, humans will create complicated machines. It might not be reasonable to even colonize the solar system right now, but 500 years into the future? How about 5000 years into the future, humans won't be building and launching generation ships towards earth-like planets, just because it's ok to live here on earth? Earth has limited resources, and the sun has a limited lifespan. If you want us to survive for more than a billion years, you'll have to colonize other star systems.

        Adaption from oceans to dry land is possible over millions of years and is possible because there exist places where the ocean and the dry land are right next to each other. Adaption from an Earthlike atmosphere to a planet X atmosphere would not be possible by natural evolution because the two ecosystems are separated by many lightyears of empty space.

    • Forbes own September 2015 article that says ad blockers won't hurt online adversiing. http://www.forbes.com/sites/ro... [forbes.com]

      This article is now blocked as well!

      • I wonder what's wrong/right with my setup? Opening this link in a new private window gets me the stock Forbes opening page, which includes a "proceed to site" link (sometimes after a few second countdown). Some dumb quote but no ads. My blocker stops 10-15 elements on each Forbes page, but I get the article. No mention that I'm running an ad blocker.

        Mac OSX 10.11.2, Firefox 43.0.3, uBlock Origin 1.5.1.
    • How CRAZY would we think it of MONKEYS who want to live underwater? We'd marvel at why happy jungle monkeys would leave a comfortable environment free of most predators and full of food to go somewhere hostile where they can't breathe, their temperature will decay, and without machine aids would soon die.

      You make some nice points, but actually, living underwater is something we can do, and should do.

      Build a hyperbaric lab (think of the South Pole stations) –with work, living, and socializing quarters. 200 m deep, 400 m deep. Each level with air pressure (and gas mix) appropriate for human function.

      Why? Oh, TONS of reasons. Medicine, microbiology, sub-cellular chemistry, organic chemistry, drug discovery, hydrothermal vent investigations, immediate access to the deep-water conditions one wants to study because you live in a large building or complex that is at 200 or 400 m under the sea

      You walk around in pants and a shirt. There is enough space that it does not feel like a jail. And instead of taking a two-week field trip as an oceanographer (or whatever), you just live at the pressure. No autoclaves, no high humidity, and an environment like a large hotel-hosted conference, with labs. In the labs, you just put on regular safety equipment.

      As for results, materials synthesis, medicine, and even some manufacturing processes would benefit tremendously from being able to rent lab space for 3 to 12 months. Vapor pressures of chemicals are the same at any given temperature.

      Humanity needs a hyperbaric lab. Pressure is a state variable, just like temperature, but a little more difficult to work with. A hyperbaric lab complex would solve this problem. It would also open up myriad new R&D projects.

      It is possible. Far more possible than a moon base, and infinitely more possible than a Mars station.

    • by TexNex ( 513254 )

      The stars call to us through the ages, with each and every one holding the promise of a future for humanity beyond Earth

      No. They don't. Humans evolved to live here, on Planet Earth. Not on our own star, or on any other star, and humanity's future is right here where we have an entire planet we were built for... not on a foreign star.

      How CRAZY would we think it of MONKEYS who want to live underwater?

      Ever heard of a SEA monkey?!

    • In reality though, most of the planet is inhospitable, except for a small portion of Africa where we evolved, and even that is no cakewalk. As physicist David Deutsch says, you could drop most of us into the environment where we live, with no advances to keep us alive, like clothes, fire, houses and iPhones, and even most friendly climates like the Southeast US where I live would kill me during winter. We rely on a lot of knowledge-based technology to keep us alive here on Earth. I don't know that it woul
  • by Dr. Spork ( 142693 ) on Saturday January 02, 2016 @05:20PM (#51227863)
    You can make human colonies in faraway places without humans having to travel there. In 200 years, I expect that we will be able to reproduce entire ecosystems from data alone. That data "recipe" could be packed into a rather small package and transported slowly to many distant solar systems to germinate into diverse islands of life and civilization. Once this becomes possible, I really doubt that nobody is going to get around to doing it. We will need an autonomous asteroid miner, ore processor, and a primitive 3D printer to produce other, increasingly more precise and specialized machines. To do their job, all they will need is the right software, lots of ordinary rocks, and the energy of a nearby star. The system will be able to build anything that we are able to build, including viable cells with human DNA, and the technology to gestate them. With careful planning, I suspect that the starter kit will fit inside the volume of a shipping container. Since the data/software will be stored in a very stable medium, these seeds will work even if their trips to the stars are slow. But if we spam the galaxy with these little seeds, the future of humanity will eventually be pretty grand.
    • This simplifies everything by at least a couple orders of magnitude in food and fuel.

    • Dr Fermi raises his ugly head again: Why has this not already been done? Bear in mind that our solar system is not that old, as stelar systems go.

      • Why has this not already been done?.

        To quote Greg Egan: That's what bacteria would do if they had spaceships

        The "Fermi Paradox" assumes that a race with that level of technology and the inclination to make long-term plans that won't come to fruition until the instigators had crumbled to dust would be stupid and short-sighted enough to set of an uncontrolled exponential growth (with the capacity to mutate and backfire on its creators). NB: its not the technology that's the issue (the human race would certainly be stupid enough) - its the matu

      • Re: (Score:3, Interesting)

        by Anonymous Coward

        "Bear in mind that our solar system is not that old, as stelar systems go."

        To be fair, on astronomical scales, yes it is. We're in the first generation of stars that could possibly have live evolve around them. So-called Pop III stars were behemoths that obliterated themselves in no time - 100,000 years or less - and were around when the universe was, oh I don't know, a few million years old or so. (Redshift of around 8 or so, whatever that corresponds to. I do my cosmological history in redshifts, and when

        • "As a result, stars of our Sun's generation are the earliest that could possibly form planetary systems. On a galactic timescale, we're first wave."

          This is exactly my point. Our stellar system is young in comparison to others we can see, and not even that distantly. We should, or should shortly be able to see, evidence of exported life in some form from these older systems.

          • Re: (Score:2, Interesting)

            by Anonymous Coward

            I think you may have slightly misunderstood (or I'm slightly misunderstanding you - it's gone one in the morning here and I'm shattered so forgive me if that's the case). If we rigidly stuck to the generations for the sake of argument, it's like this:

            Pop III: Nothing.
            Pop II: Not enough heavier elements for life.
            Pop I: The Sun. Us and a few other first-wavers. Every chance we're so far from each other we'll never have a single hope of knowing each other exist, especially since we have no idea if our technolo

  • Without all the crap (Score:3, Interesting)

    by Anonymous Coward on Saturday January 02, 2016 @05:27PM (#51227895)

    Is Interstellar Travel Possible

    For generations, when we looked out at the distant stars, we could only wonder whether there were planets and the conditions for life-as-we-know-it around them. The past 25 years have brought forth a revolution in planet-finding, with thousands of known, confirmed planets, including many of potentially habitable, Earth-like worlds. But could we ever get there? Reader C. Vidal wants to know:

    Do you think interstellar travel is possible (by any civilization). It seems to me that all possible solutions are one way trips.

    When it comes to interstellar travel, I definitely do think it’s possible. But there definitely are constraints, dependent on how we’re willing to do it.

    1.) Conventional Technology. If all we’re willing to use is the technology we have today, we could, theoretically, reach another star. By building a large enough ship that we could have a sustainable mini-civilization — a “generations ship” of sorts — we could boost up to speeds of tens or maybe even hundreds of km/s, growing our own food and recycling our water along the way. An alternative would be to develop cryogenic freezing-and-thawing technology, where humans, plants and other living creatures could be transported in suspended animation (a la Thundercats), only to be reanimated and revived upon arrival.

    Some “standard” concerns, like collisions with interplanetary/interstellar objects, like rogue asteroids or planets, are actually not particular causes for concern. These objects — although plentiful — are so low in density that strikes even between stars are extraordinarily unlikely, even on million-year timescales. A trip like this would take hundreds of thousands of years to reach the nearest star system, and seems to be within reach.

    But this is the ultimate one-way trip, and not at all a satisfying solution.

    2.) Future Technology based on known Physics. But if we’re willing to consider other technological possibilities, we can certainly do better. In particular:

    Fuel improvements: rather than using chemical-based rocket fuel, which releases about 0.001% of its mass into energy which can be used for thrust, we can use nuclear-based fuel (which is about ~1% efficient), or even antimatter-based fuel, which would be 100% efficient.
    Thrust improvements: if we can transport large amounts of matter-and-antimatter for fuel on board a ship, we can continue to accelerate along our journey. Since humans can withstand (and even prefer) thrusts that are similar to Earth’s gravity, we could point our ship towards our destination, fire the thrusters at 9.8 m/s2, and when we reach the halfway point, point the opposite direction and fire again, decelerating until we reach our destination.
    Time improvements: because this will bring us close to the speed of light after only a few years of acceleration, we could get to pretty much any star we choose in no more than 20-40 years of travel.
    This would be great, because we wouldn’t need a ship to last for generations. Sure, it’d have to survive traveling at very high speeds through the interstellar medium, but a strong enough magnetic field (and a map of neutral gas clouds to avoid) should take care of that. And if we can master the cryo-freeze technology, we wouldn’t even need to bring resources other than seeds to plant and eggs to incubate upon our arrival.

    The downside, though, is that a one-way journey might only take a few decades from the perspective of the person on the journey, but that’s due to special relativistic time dilation. If we’re visiting a star hundreds or thousands of light years away, then hundreds or thousands of years pass here on Earth. Even if we make this journey, our prospects of communication with anyone still on Earth (assuming there is still anyone here on Earth that far in the future) will have to be with their distant descendants. The journey need not be one-way for the people who go,

  • The only method we could have access is generation ship. And access is a big word seeing how much resource we would need and some problem at the moment seem quasi intractable. The rest, is speculation as we have no way to create anti matter and store it in meaningful quantity and speculative tech is just that : speculative. This is just a fluff piece from forbes. Probably something they have in stock for long holidays while writers are away.
  • by HiThere ( 15173 ) <charleshixsn@earthlink. n e t> on Saturday January 02, 2016 @05:41PM (#51227951)

    FWIW the only validated method is slower than light, and, due to energy considerations, at considerably less than 1G. There are, IIUC, speculative ways around the light barrier, but they're all quite dubious. Perhaps one of them would work, but not with any foreseeable technology.

    That said, there could be some kind of breakthrough, eventually, but it hasn't happened yet. Were I to bet, I'd bet on ion rockets with around 100-200 pounds of thrust as the way most likely to succeed. And this might be doable with fission power, but may well require fusion. (Light sails require either an even lower thrust, or trusting someone back home to keep your engine running for several centuries.)

    For various reasons I don't expect any group to set out aiming to reach distant stars, but rather aiming to live off the Oort cloud, and eventually deciding to make the jump to another one. Or via a series of loose planets. When resources are rich, build a second ship and then the two of you go your separate ways. Eventually some of them would end up on other solar systems, but this would just be because that's where resources were thickest, and nobody was defending them. (Sort of "life as a von Neuman Probe".)

    N.B.: For various reasons these ships would need to be quite large. A question that hasn't been answered is "What is the minimum number of people required to maintain a technological civilization?", but presumably laser communications would be possible and cut down the minimum number. So say a stable population of 100,000 or more. And not too crowded, as that causes increased unrest...and it's already going to be stressed as there's going to be needed a firm limit on the size of the population. Virtual reality is also going to need to be well developed to defuse social stresses.

    P.S.: Don't suggest suspended animation. Interstellar space is where these people are going to live. Planets will only be occasionally visited for special reasons. And will probably only be visited by robots.

    Now give me a magic space drive and all this changes, but I'll believe it when I understand that it can actually be built.

    • N.B.: For various reasons these ships would need to be quite large. A question that hasn't been answered is "What is the minimum number of people required to maintain a technological civilization?", but presumably laser communications would be possible and cut down the minimum number. So say a stable population of 100,000 or more....

      Yep, a large population.

      But one quibble with communications: Lasers have divergence. On human length-scales, they are close enough to being collimated. On interstellar, or even just Earth-local stellar, beam divergence means loss of signal at greater distances. Satellite-to-satellite communications by laser are hampered by this.

      Lenses don't help, and in any case, because lasers are coherent, there is the problem of 'laser speckle' on the receiving end. That is, nano-scale imperfections in your laser wi

  • by Sir Holo ( 531007 ) on Saturday January 02, 2016 @05:57PM (#51228011)

    How did this get posted the the /. main-page? Forbes is a magazine about money, with a known editorial slant. The article's author apparently discovered science fiction novels, and then perused Wikipedia for all of his sources (except for a pic or two from NASA/JPL, which are public == free).

    WP is great, but for some bozo to lazily summarize a few WP articles, all written by many volunteers, including their fair-use images, and then selling it in a for-profit magazine w/website is disgusting.

    It's totally against everything that Wikipedia is about. Ah, but it is also everything that Forbes is about. So there is that.

  • by Sir Holo ( 531007 ) on Saturday January 02, 2016 @06:23PM (#51228119)

    By interstellar medium, does the author mean "space." That is, dimensional space but a very hard vacuum.

    Isn't interstellar space somewhere around 10^-25 Torr, or roughly one atom per cubic meter? (I did not check my math for the conversion, so go easy on me.)

    For comparison: On Earth, we can build usable vacuum chambers that go down to about 10^-13 Torr, at room 'temperature'. Lower than that, hydrogen just seeps through your chamber walls as if it they were a sieve. And a single fingerprint can out-gas for a month.

    There is NO interstellar "medium". It is called space; void.

  • by burtosis ( 1124179 ) on Saturday January 02, 2016 @06:57PM (#51228257)
    Before going speculative about teleportation and work holes, but past antimatter propulsion is a miniature black hole power source. A million metric ton black hole would radiate about three terawatts (with less mass dramatically raising the radiated power) and you could use magnetic fields to pump in material from in front of the ship. It would eat anything even photons and nutrinos. It should be able to power a decent sized ship and would be the most ideal power source known to modern physics.
  • .... if one is travelling sufficiently close to the speed of light, time dilation can make a trip that would take many thousands of years only seem to take a tiny fraction of that for those on board the space craft.

    And with the quantum vacuum thrust engine, which would not require the mass of any fuel to be brought on board, the kind of lengthy accelleration times involved to get up to such speeds should be entirely feasible.

    • The quantum vacuum thruster might be a dead end - right now it's just a few interesting results that are likely just the result of experimental error. It's going to need a lot more confirmation yet. Even those few interesting results haven't made peer review journals. Even if it does pan out though, and the physics actually works, it's still not fuelless. It's propellentless, but it does need energy, and a lot of it. Solar panels are essentially useless in interstellar space, so you'll still end up slowly b

  • I click on the link using IE 10 with AdBlock Plus with EasyList enabled which takes me directly to Ethan Siegel's blog for Forbes. Loads instantly with all images. No adds. No problems.
  • by supernova87a ( 532540 ) <kepler1@NOspAM.hotmail.com> on Saturday January 02, 2016 @08:06PM (#51228499)
    Oops, I was hoping that the article was about 3 different seating classes for the interstellar travel, as in:
    • -- 1st class (extra legroom, all-you-can-breathe oxygen, plus massages)
    • -- Business (minimum guarantee not to be ejected to space if energy concerns)
    • -- Economy frozen (we'll wake you up when you get there, though may incur extra $50 fee)

    I dearly hope so. For those who can barely tolerate the rest in steerage, imagine decades with your fellow man!

  • Come to beautiful Alpha Centauri, and stay at the Holiday Inn. It's within walking distance to McDonald's, Wendy's, and Wal-Mart.

"Love may fail, but courtesy will previal." -- A Kurt Vonnegut fan

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