1. Uberwatch
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    Uberwatch Active Member

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    Engine required for FTL Travel?

    Discussion in 'Research' started by Uberwatch, Oct 3, 2013.

    Well recently I made a scientific mistake that nuclear fusion engines are good for FTL as part of my story. I was wrong when I found out it only goes 10% of the speed of light. So although Alpha Centuari Proxima is 4.3 light years away, it would take around 40 Earth years to get there using NF engines according to what I researched.

    Would it be ion powered or anti-matter? I just need an explanation on a theorized type of engine propulsion where ships could travel at FTL to distant star systems.
     
  2. Thomas Kitchen
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    Thomas Kitchen Proofreader in the Making Contributor

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    Google is your friend, in this case:

    http://en.wikipedia.org/wiki/Faster-than-light

    That's just one website. There are loads more. :)
     
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  3. Uberwatch
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    Uberwatch Active Member

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    Ah, I was looking at the interstellar travel wikipedia page. This is more like it. Thanks.
     
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  4. Thomas Kitchen
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    Thomas Kitchen Proofreader in the Making Contributor

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    No problem. Have fun! :p
     
  5. Edward M. Grant
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    Edward M. Grant Contributing Member

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    The only theoretically possible form of faster-than-light spaceflight I'm aware of is the Alcubierre warp drive, and that seems extremely unlikely to work in the real universe. It also blasts the destination with extremely energetic radiation when you stop, which makes you a bit unpopular with the natives ('terribly sorry about exterminating all life on the dark side of the planet when we arrived').

    It's the one I use in my 'hard SF' space opera stories.
     
  6. Uberwatch
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    Uberwatch Active Member

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    Okay, then what about a type of propulsion that can go at the speed of light.

    If it takes 40 light years to get from Sol System to Star System A, then the type of propulsion will meet up with that distance. I did some research on other science fiction works and there was this movie called Avatar that had this freight cruiser that was powered by matter-anti matter propulsion. It goes to Alpha Centauri A which is 4.3 light years away, but takes around 6 light years for the ship to get there.
     
  7. Cogito
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    Cogito Former Mod, Retired Supporter Contributor

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    Nope. Not unless you can make mass disappear entirely. But once you do that, time ceases to pass for you, so you have no way to return to normal space.
     
  8. Edward M. Grant
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    Edward M. Grant Contributing Member

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    Matter/antimatter is about the most efficient energy source you can get, because it converts the entire mass of the fuel into energy. I'm not sure what Avatar planned to use, but typically the designs I've seen seem to throw that energy out the back as photons, which gives the most efficient propulsion but is very low thrust.

    Avatar probably isn't a bad place to start, though. From what I remember they did pull in some scientists to check their spacecraft designs, so they should be at least believable, even if not realistic.
     
  9. KaTrian
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    KaTrian A foolish little beast. Staff Supporter Contributor

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    Since we don't have anything that'd work very well even in theory, you'll just have to do what many others have done, create a facsimile of believability.
    Matter/antimatter is proposed as a propulsion option for non-FTL travel, but please correct me if I'm wrong. I'm not sure could that energy be used to do the warp thing, 'cause you'd really require an insane amount of energy for the drive to work.

    In the end, you'll just have to dance around the specifics. Especially if you aren't an astro-physicist, or more like, planning to become one.
     
  10. Edward M. Grant
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    Edward M. Grant Contributing Member

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    As far as we know, you can't beat antimatter as an energy source; you can't do better than converting the entire mass of your fuel into energy. The big problem is that there are no antimatter mines; you first need to convert all that energy into matter before you load it into your starship to use as fuel, and that means you need to produce more energy than you'll use on your trip from another source, probably many times more when you allow for conversion inefficiencies.
     
  11. Burlbird
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    Burlbird Contributing Member Contributor

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    I'm not an astrophysicist, but I'd say your engine needs to work on either handwavium or unobtainium to successfully and in a space-opera-firendly fashion band all those pesky laws of the universe :D
     
  12. Uberwatch
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    Uberwatch Active Member

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    I think the fictional element like unobtanium as you said is how Sc-Fi writers get a way with it easily and realistically. It's tough trying to remain in real-world science for storytelling without the knowledge of astrophysics.
     
  13. Notastatistic
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    Notastatistic New Member

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    Well said.

    I admit some sciences are a way too difficult for many to write about but there are some that writers can very well write about.
     
  14. StoryWeaver
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    StoryWeaver Member

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    I used to teach physics in another life... Take a look at the Lorentz time transformation formula,
    https://en.wikipedia.org/wiki/Lorentz_transformations
    it is not that hard actually, simple algebra in its basic form. If your space travelers do not mind being youthful when their friends back on earth age and die during your travelers journey, it is quite feasible to accelerate at a reasonable rate and then travel close (e.g. even 0.9c) to the speed of light (=c) and make a long journey in what seems like short time actually to those making the journey. Carl Sagan once said if you could travel close to the speed of light, you could circumnavigate the known universe in your ship in what to you the traveler would seem to be about two years of your time.
     
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  15. Notastatistic
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    Notastatistic New Member

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    Good point. I admit I don't like messing with it since my knowledge of the ideas are a little superficial, however there's probably a good entry to just using it as a element. It's more than a element if used wrong. I don't use physics really if I could. Some soft sciences might be worth exploring. Hard science is something I do wish I could manage. However, I think that we usually find ourselves trying to rethink what we'd like to write about. This for me is how I approach the genre I write in. For example a colony story could use psychology. Or maybe even sociology. Whether it is easier to write, I do not know. I just like this approach since a math equation, can answer things. However I'd rather the story have characters, and other subjects that need to be explored.
     
  16. Morgan Willows
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    Well, matter/anti-matter and Lorentz transformations has been covered so I don't really have anything to add.
    There is always the good old fashioned 'make it up' method - I mean, Star Trek has been doing it for decades - it all depends on just how hard you want your SF to be.

    Avatar did make mention of 'unobtanium' but the substance they applied the name to was a room-temperature superconductor (which is why the little chunk of the stuff was floating on that stand in the mining-manager's office) which, while it is a world-changing level of amazing, wouldn't be much help in an FTL engine, I don't think. I'm not sure what they were using engine-wise.

    I think your best bet is finding some very theoretical stuff and extrapolating as best you can to make a convincing hand wave, which you seem well on the way toward.
    You might be able to 'believably' stretch the efficiency of a matter/anti-matter engine by making use of dark matter since not much is known about the stuff other than it neither emits nor absorbs light or any known electromagnetic radiation and there seems to be an awful lot of it.
     
  17. Low
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    A fusion warp drive employing matter and antimatter fusion would release twice the amount of energy as opposed to just matter fusion. But the engine would require a fission core trigger to go live. Thats a theory anyway. Have fun with that. The engine would have to be the size of a small country. Ha. :cool:
     
  18. Cogito
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    Cogito Former Mod, Retired Supporter Contributor

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    Matter-antimatter reaction releases a minimum of about 100 times the energy of atomic fusion. That's assuming a fusion reaction converting about 1% of the reaction mass to energy, which is extraordinarily high. Matter-antimatter converts ALL the mass to energy, assuming equal masses of matter and antimatter.

    As for estimating the size required for a matter-antimatter reactor, that is pure speculation. Unlike fission or fusion, there is no concept of critical mass in matter-antimatter reactors. If you could make a positron emitter the size of a fountain pen, and suitably compact gamma collectors, you could have a breadbox-sized matter antimatter reactor. But you had better have some damned good superconductor busses to draw off all that power quickly enough to avoid vaporizing your reactor.
     
  19. StoryWeaver
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    StoryWeaver Member

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    I don't read space scifi so my knowledge of that genre is very limited. I wonder how many novels in that area address the issue of cosmic rays bombarding the ship? If not, you might add it in your novel and help lend credibility to the science that some readers might be asking in their heads? Cosmic rays are deadly enough at normal speed, but at FTL it is like sticking your head out a car going 90mph and with a raining downpour-- the rain droples (cosmic rays) pellet you far more than just standing in the rain. barreling through space, an advanced propulsion system would need to have solved the issue of massive cosmic ray bombardment of the ship inhabitants (I was told this even by a writer of an epsiode of Star Trek the Next Generation, even she was a disbeliever in traveling any significant time/distance space because of that-- however I tend to think advanced civilizations will have found a way, i mean just look at humans; we were riding ponies and steam trains just a couple of hundred years ago, so imagine a scientific civilization a 100,000 years+ beyond our own.).
     
  20. StoryWeaver
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    StoryWeaver Member

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    came across this-- NASA discussing FTL warp drive:
    http://www.extremetech.com/extreme/136408-nasa-working-on-faster-than-light-travel-says-warp-drives-are-plausible
     
  21. B93
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    The harder you try to explain it, the less believable it will be. Make up a name and a set of rules for the effects and go with it. "Any sufficiently advanced technology is indistinguishable from magic."
     
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  22. Robert_S
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    Wouldn't that be a reactor and not a propulsion engine?

    AFAIK, there currently is no propulsion engines even in theory. Engines are an...wait for it...engineering problem and until we can solve the problem of the science for generating the energy needed for FTL, engineering can't begin to work.

    However, the two top FTL theories are wormholes and the Alcubierre Warp drive.

    The top pic is a graphic representation of the Alcubierre Warp drive's effect on spacetime outside of the ship's frame of reference.
     
    Last edited: Nov 10, 2013

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