Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

A problem with interstellar travel

  1. May 26, 2017 #1
    Hi guys,

    I am writing an undergraduate screenplay about physicist. The physicist is working on a mission with the aim to fly a spaceship with human crew to an extremely distant planet with an environment suitable for humans.
    Its really not that important for the story, because the film is drama not sci-fi and moves on to be about something completely different (the colonizing mission just stands for the abstract variable "The great cause"), but still - the physics has to be plausible (in theory is absolutely enough) otherwise the audience disconnects.

    I have the abstract idea and need to fill in particulars:

    So here is what I need to find out:

    1. the theory of how the interstellar flight would be possible - In the movie the mission and how it works will be presented at university for students of astrophysic, even the freshmen so it should be in easily understandable language. (Just a possible theory is enough. I liked the black hole starship idea, but the reason that I cant just wikipedia this whole thing is the presence of the next point)

    2. The theoretical problem of this interstellar flight that needs to be solved by the physicist for the mission to be possible - The main hero works on this theoretical problem (something like Michael Caine in Interstellar having to solve some theoretical problems for the whole thing to work). I actually dont need to understand this theoretical problem or have the solution. I need just, say, snippets for two movie scenes:

    a) Other physicist says during presentation that our protagonist "is going to give us the new world" to which main hero humbly replies that its only small portion of the project and very briefly - again in simple language - explains what the theoretical problem is.

    b) On the meeting of professors, other professor attacks (and he is correct) protagonists latest advancement in solving of the problem - (and this actually should be highly technical because they are professionals talking). The scene is really about heros work being threatened, but it has to have realistic feel. So 1-2 sentences of criticism in technical terms is all i need. Ideally formulated as a criticism of professional directed to another professional.

    I will be very grateful for any help.

  2. jcsd
  3. May 27, 2017 #2

    Vanadium 50

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2017 Award

    I don't believe this.

    Did the audience disconnect from Star Wars?
  4. May 27, 2017 #3
    Star trek did OK with things like warp drives and teleporters, both of which seem utterly infeasible according to today's accepted physics.
    (While the Alcubierre drive is possible in theory, in practice it is unrealistic), but anyway the warp drive was explained by 'dililhium crystals', while the teleporters made use of the 'subspace continuum'.
    Somebody once said in here (I think) that genuine sci fi has has to be based on scenarios that are at least somewhat plausible,
    everything else is space drama or similar, but nevertheless can be good entertainment,
  5. May 27, 2017 #4


    User Avatar
    Staff Emeritus
    Science Advisor

    There are many ideas of how interstellar flight would be possible. Some involve known physics, others involve hypothetical (but not disproven) physics, and others require things that outright violate our current understanding of the universe. Can you narrow things down a bit?
  6. May 27, 2017 #5
    I too have to disagree with this. Being internally consistent is critical, and adhering to currently proven knowledge is important. But you can get burned if you start building off of science speculation like string theory or dark matter. Imagine if you had built cold fusion or the "Big Crunch" into your premise.

    Flaws in older series can get grandfathered in if they were popular enough, but new stories making the same mistakes won't be forgiven. A good example of this is R2D2 not being able to speak english. In 1977 the general public might not have seen anything wrong with this, but in a new series it would never work.

    So for your story, you are better off keeping your FTL solution in the background and not too important to the plot. Have vague references to something totally outside real science - an elementary particle of location, perhaps?
  7. May 30, 2017 #6
    Thanks for all replies, sorry I couldnt answer sooner, too many deadlines closing :)

    Sorry, I was not precise in my formulation. I meant that it has to sound realistic (in the sense that general audience feels like that is something e.g. a professor could say when introducing the mission) or the audience disconnects. However, for obvious reasons, even if you could afford it without loosing your audience you dont want that theory to be a complete hogwash. You dont want a film supposed to be realistic to be tainted in this way. And imagine the pure dread of physicists watching.

    But of course I can afford a leeway. E.g. if there is some proposed principle for interstellar flight, but we, lets say, didnt yet discover the hypothetized matter crucial for it to be possible, It can be dealt with as already discovered in my film universe.

    this is exactly what I have in mind

    I would also say there is a different standard for realism for space operas like Star-trek and realistic dramas (for many different reasons). If I would be doing sci-fi film and in the first scene the spaceship travels through warp, everyone is fine with it. Yet if I just shot a ship through warp in my drama, without having professors solving it, without realistically sounding theory, without all these components grounding it to reality, it would ruin the whole film. Because its a drama set in the year 2017 I have to present it as a thing possible in my movie universe in a very particular way, otherwise even if it will be internally consistent with the rules of my movie universe it can ruin the film.

    Know physics would be probably best, it can be slightly hypothetical but i wouldnt want to go to mindf⋆⋆⋆ territories like multiverses.

    I thing I would be to able to do this myself sufficiently enough for this movie, using wikipedia and articles, werent it for
    2. The theoretical problem of this principle of interstellar flight that needs to be solved by the physicist for the mission to be possible
    (this theoretical problem doesnt need to be solved and wont be solved in the movie.)

    So all I need for the movie is:

    1. The principle of this interstellar flight presented by professor to an audience in popular science language (Very generally in few sentenes, as concise as possible)
    2. The problem with this principle that needs to be solved by theoretical physicist-our hero again presented by professor in popular science language to an audience (in few sentences, as concise as possible)
    3. 1-2 sentences of criticism of heroes latest advancements in the solving of this problem by another professor on meeting of the professors

    So the choice of the principle of the interstellar flight should be suitable for these needs (e.g. if the principle is so complicated/advanced that it can be explained only to professionals its not suitable)
    Last edited: May 30, 2017
  8. May 30, 2017 #7
    The only method for interstellar travel which does not violate GR is a very long duration journey involving either suspended animation or a generations ship.
    Your physicist will have to either successfully falsify GR, or come up with solutions for the very long journey.
    The first I would say is wishful thinking, the latter may be feasible although not with present technology.
    Even if the transport problem as such is solved, there remains the problem that if the ship is to return to Earth it will be at least centuries later for most stars.
  9. May 30, 2017 #8


    User Avatar
    Staff Emeritus
    Science Advisor

    There are a few others that don't violate GR, though they do require exotic forms of matter that aren't known to exist. The Alcubierre drive is one such method, as are wormholes.
  10. May 30, 2017 #9
    Thank you very much! Alcubierre drive it is. Do you have any ideas for points 2 and 3?

    2. The problem with alcubierre drive that needs to be solved by theoretical physicist presented in plain language in few sentences.
    3. 1-2 sentences of criticism of heroes latest advancements (it doesnt matter what is the advancement, the point is he made som progress and then its being discredited) in the solving of this problem by another professor on meeting of the professors (its okay for this to be very technical)
  11. May 30, 2017 #10


    User Avatar
    Staff Emeritus
    Science Advisor

    Nope. I don't know enough to give you a plausible answer.
  12. May 31, 2017 #11
    If the barrier has to be the trip itself, then you have a problem: We do currently have the ability to send objects to other star systems. The Voyager probes are doing this.

    What we can't currently do is:

    - Make the journey in less then hundreds of thousands of years.
    - Survive the trip.

    We can be confident that given time and effort, we can build a ship that could go, perhaps, 1/10th light speed. This doesn't need any theoretical breakthroughs, just engineering ones. But even if the trip could be made in a few hundred years, surviving will be the harder problem. The many failures of the Biosphere 2 project show us that we are quite far from creating a generation ship. Breakthroughs in biology, engineering, psychology and even politics are needed. Hibernation or cloning sounds more reasonable to me.

    Under the cloning model, the ship would contain biological samples of all life forms needed at the new planet. When it arrived, it would clone all the plants and animals, terraform the planet, and then clone humans while somehow implanting knowledge and memories so that the humans could function. Obviously there is no guarantee that any of this is possible. But if it were, then the ship needed would be much smaller (and hence faster) than a hibernation ship.
  13. May 31, 2017 #12

    Vanadium 50

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2017 Award

    But they make up less than 0.01% of your audience. Shouldn't you be writing for the 99.99%?

    I still object to the idea that this has to be accurate. Suppose what you needed was something called "warp drive", but to make "warp drive" work, you need to power it with antimatter, and everybody knows that just leads to a big explosion. Until a material called "dilithium" was discovered that could moderate this reaction. This fulfills your requirements, I believe.

    Utter hogwash. But it didn't get in the way of the story. (In fact, the hogwashy nature helped propel the story the last time this was used)
  14. May 31, 2017 #13


    User Avatar
    Staff Emeritus
    Science Advisor

    Why? Isn't that one of the purposes of this forum? To help people get their science accurate?
  15. May 31, 2017 #14
    Any story that relies on hypothetical science to explain the reality of the story world is sci-fi. It can be sci-fi and drama at the same time, though. That's also cool.

    Other than FTL travel, cryogenics, or generation ships, you also have the option of time distortion by travelling at relativistic speeds (in excess of 99.9% light speed without going over), depending on how much space you have to cover. You know, the twins paradox where the traveller barely ages on his voyage and comes home to find his brother's an old man now.

    Most people avoid that one, though. Even Orson Scott Card left that out of his adaptation of Ender's Game.
  16. May 31, 2017 #15
    Or if the destination star is more than say 20ly, the returning traveller is more likely to discover his brother is now dead, although had lived to a good old age.
    For the brother on Earth, the outbound journey to a star 20ly away at very nearly light speed will take 20 (+ a bit) years and the same time to return.
    The fact that the traveling brother ages more slowly while away doesn't alter anything from the stationary brother's point of view.
  17. May 31, 2017 #16


    User Avatar
    Gold Member

    You are missing the point of vanadium's post, which is that it isn't necessary to the success of the story. In fact it is irrelevant to the success of the story that it BE accurate, as has been proven by many scific books/films. It's quite enough that it just not be off-putting to the audience.
  18. May 31, 2017 #17

    Vanadium 50

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2017 Award

    Phinds has this right - it's not necessary for the success of the story. A good thing too, since the premise is based on something that appears to be impossible. Having the author struggle to make something "the least impossible" if it isn't necessary for the success of the story seems like something that you should only do if you really, really, really want to.
  19. May 31, 2017 #18


    User Avatar
    Staff Emeritus
    Science Advisor

    No, I understand his post perfectly fine.

    I agree that it isn't necessary for a successful story, but there are plenty of authors who put in a lot of effort to make the science in their stories as accurate as possible and lots of readers who appreciate this. There is no point in trying to beat it into someone that they don't have to make their science accurate. It's their choice.
  20. May 31, 2017 #19
    There's a pretty good list of known/possible intersteller drives at the Tau Zero Foundation website (https://tauzero.aero/making-progress/propulsion-ideas/). You might look at the Bussard drive, it seems the most practical to me and you should e able to cook up some problem that needs to be solved to make it work, for instance developing a polarized field to collect hydrogen (the "scoop"), or designing a shield against very energetic particles other than hydrogen? When your ship gets going at relativistic speeds you need to worry about running into things...
    Last edited: May 31, 2017
  21. May 31, 2017 #20
    Thanks for all contributions!

    Well, its not either/or situation so ideally I want to write for both.

    But no one really seems to be holding this idea. I put it rather clumsily in my first post so I addresed it in second - the point is not that the science has to be accurate. Audience just have to percieve it as reallistic (talking about my movie, for the more general statement not off-putting is much better suited.). This really depends on the form much more than on the content, because of audiences lack of knowledge in this sphere (of course there is a limit of to what you can afford content-wise).

    To expand on that - I think this particular example you offered wouldnt sit well with my movie because a) it appears too simplicistic. b) because of the cultural context - warp drive is in the mind of average viewer so strongly connected to space-operas that it would detract from realism.

    On the other hand the Bussard drive concept sounds sophisticated. And sure, if I replaced hydrogen with different chemical element and made it all hogwashy it would have zero impact on the audiences perception. But even if I can, I simply dont want to do any such thing - because of the 0.01%, because its nice to do everything as right as possible in your movie and because many people can appreciate it.

    This sounds wonderful, thank you! :)

    Are the problems you mentioned something a theoretical physicist could work on?

    If yes, do you possibly have an idea for what the criticism of some advancement of solving this problem could be? (in technical language - talk between professors.)
    Last edited: May 31, 2017
  22. Jun 1, 2017 #21


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    If you cater to 0.01% of your potential audience, then you don't have much future in the entertainment industry - if you don't mind my saying.
  23. Jun 1, 2017 #22
    I might just have, if it doesnt detract anything from the experience of 99.99%
  24. Jun 1, 2017 #23
    I'm afraid not. I have my own ideas concerning realistically designing a hundred thousand mile scoop field, or a practical shield against high energy particles, but I'm an engineer, not a theoretical physicist.

    If you want my personal opinion, I'd ignore the theoretical physicists anyway. <Moderator's note: sentence edited for language>


    If you want a real scientific opinion, I'll suggest exploring this; if you subscribe to relativity theory you see why there's no point to "faster than light" (FTL) travel. Look at what happens to spacetime as velocity approaches "c". Time goes to zero, distance goes to zero and mass goes to infinity. It's a simultaneous solution of multiple partial differential equations, but the directions are unequivocal; as any massive body approaches the speed of light, it's everywhere at the same (all) time(s). You just need to figure out where you want to get off the train, and you don't know where you're going to be exactly when you get there, because you've never been there before and you don't know anyone who has?

    Could make a good story. If you want to write about it let me know. Post a disposable address and I'll reply if I ever get back here. <Moderator's note: posting personal contact information is against PF rules> Somehow.

    So stick that one in your theoretical pipe and smoke it :)
    Last edited by a moderator: Jun 2, 2017
  25. Jun 2, 2017 #24


    User Avatar
    Science Advisor

    Well, sounds an awful lot like Interstellar. Note that Interstellar uses wormholes for long distance travel. It also doesn't try to explain the technology of the spaceships or of antigravity in any detail. Science buffs have plenty to gawk at from the black hole simulations and the random field equations on black boards. It's more interesting and authentic to focus on the physics we understand well (i.e. time dilation) and how they affect the story, than to focus on the parts of physics which need to be modified for story purposes. If you give us enough of the former, we don't care if you don't explain the latter.
  26. Jun 3, 2017 #25
    There are several theories about how interstellar flight might be possible, some more credible than others. The Alcubierre FTL drive, for example, is mathematically possible on paper, but what they don't tell you is that you would require the entire mass of Jupiter converted into pure energy before it can be used once. So unless you intend to denude solar systems of their planets every time you make an FTL jump, it is not a very credible idea.

    On the other hand, credible concepts are not always ideal to the story you want to tell. For example, you could travel between the stars without traveling faster than light. A spacecraft cable of continuous one gravity (9.806 m/s2) thrust would be able to travel from Earth to Proxima Centauri 4.24 light years away in 3 years, 6 months, and 15 days from the perspective of those aboard the spacecraft, and 5 years, 10 months, and 13 days from the perspective of those on Earth. This is the result of the time dilation after approaching 94.95% the speed of light at the mid-point. While this method may seem more credible than consuming planets for fuel, the reality is you could never bring along enough fuel to reach your destination. Even if the spacecraft mass was 99% antimatter and the engines 100% efficient, you would still run out of fuel long before you arrived at your destination. The only way such an interstellar trip would be possible is if they either manufactured or collected fuel along the way. So unless you intend to have the travel time between stars take years, the more credible concepts are not always the best solution.

    Viewers/Readers of science fiction are ready to suspend disbelief, or they wouldn't be interested in the genre. The biggest problem most science fiction writers have, in my humble opinion, is that they try too hard to describe in detail how everything works. While this can certainly add plausibility to a story if they get it right, it can also destroy plausibility if they get it wrong. When trying to explain future devices it is sometimes better to just describe its function and not how it works. In other words, leave out the "techno-babble." Let the viewer/reader use their own imagination to fill in the technological omissions.

    You mentioned the movie "Interstellar" and that is a classic example of a science fiction movie that got it completely wrong and as a result lost all "plausible deniability." The concept from the very beginning was flawed. While the Einstein-Rosenberg Bridge (a.k.a. "Wormhole") is certainly mathematically possible, it requires two black holes to form a connection - one at either end of the wormhole. Black holes, of course, are greater than three solar masses. What do you think would happen if you put a three solar mass object right next to the planet Saturn, as they did in the movie "Interstellar?" That physics mistake alone made the entire movie unwatchable.

    The biggest stumbling block to interstellar travel is ultimately power. Whether you are moving faster than light, or warping space/time with an Alcubierre FTL drive, or simply generating 1 g continuous thrust and spending years traveling between the stars, it all requires vast amounts of energy. Antimatter seems to be the pinnacle of how much energy can be produced from mass (e = mc2), so maybe your hero could discover a means to manufacture large quantities of antimatter cheaply.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted