Interstellar war

Discussion in 'Science Fiction' started by Meteor, Jan 2, 2017.

  1. psychotick
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    psychotick Contributing Member Contributor

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    Hi,

    I think I wouldn't worry too much about the warp effect on a planets gravitational accumulation. Ships are small relative to planets (except forEE Doc Smith's stuff) so it's likely that the warp field they generate would also be relatively small. In order for a warp field to do as suggested, it would have to significantly warp spacetime over a significant portion of the planet. But in any case you could simply use some sort of handwavium to explain that ships can't use warp drive in a gravitational field and problem solved.

    As to your war, if both sides have planet busters then you end up with a MAD - Mutually Assurred Destruction scenario where neither side can afford to launch. That doesn't mean there can't be accidents etc which would escalate to galaxy war one.

    But the real issue you have is why the war at all? If this is a crusade of some sort for one race - religious or idealogical or what have you - then you're talking fanatics. And fanatics would launch. Death be damned! And if it's not then what are they fighting over? There are two hundred million stars in the Milky Way give or take - plenty of resources for everyone. Likewise territory isn't much of an issue either for the same reason. Not if they have a drive that can carry them across the galaxy in a month. And do these races even breathe the same air etc? The very scale of these races' FTL drive makes most scenarios for war unlikely if they each only have a dozen or so planets. Now if they had tens or hundreds of thousands of worlds each, that would be something else. But as it is you're talking about two races each with a dozen marbles or so, in a country. They would hardly ever interact with one another.

    Cheers, Greg.
     
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  2. Meteor
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    Meteor Active Member

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    Hi!

    I can see what you mean with MAD which is why I don't intend to include many planet busters. That's if I include any at all. Plus they're counter productive. In my earlier posts I mentioned that nation A is after nation B for its resources as well as their manifest destiny ideals. Really this post is all hypothetical, but it does have my brain putting something together. I really just wanted a basic idea of how one might look. The actual idea I asked this for will definitely need another look after looking over all the answers I received. The actual story has a full galaxy.
     
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  3. zoupskim
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    zoupskim Contributing Member Contributor

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    ... I don't have anything to add, but this thread is so flippin' cool.
     
  4. Zadocfish
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    Zadocfish Member

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    Something I remember from an old sci-fi novel (the Wailing Asteroid, by Murrey Leinster), a concept I LOVE and intend to use eventually, is a space-WMD that works based on artificial gravity. Basically, it's a small drone or ship that warps space around it to give it the effective mass of a star, and then it just drives right through whatever system it's sent to destroy. Not sure how plausible that is... but FTL would involve a lot of things that would bend or break natural physical laws, so I think that gives sci-fi writers a license to get creative with weaponry.
     
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  5. newjerseyrunner
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    newjerseyrunner Contributing Member

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    A space warping object moving through space would require time to disrupt the orbits of the planets. Maybe a year.

    Warped space is not sci-fi, it's general relativity.
     
  6. Iain Aschendale
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    Iain Aschendale Contributed Member Contributor

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    What if you just wanted to cause an extinction? Could you chuck, say, the Space Shuttle at 5% of the speed of light at a planet and kill everything on it? Asking for my own story that's dissimilar to this, but has a couple common points.
     
  7. Cave Troll
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    Cave Troll Round and round, spiraling into madness they do. Contributor

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    You might want to hit the planet quite a bit harder than 5%. Though we don't know how big the planet is, and what the propulsion system of
    of the shuttle is, etc. If you are using something similar to what already exists, it will have to be roughly 50-60% to have energy to have the
    effect you're looking for. At 99-100% you can totally obliterate the planet into a mess of space debris.

    Turns out the smaller the object, the more energy/velocity will be needed to have a catastrophic effect. Not that I can do the math, but
    a metal rod about 100lbs traveling at c, will have have more destructive energy than a shuttle moving at 5% c. Though it will take more
    rods to have the same effect as the shuttle if both are traveling at c.

    Ultimately IDK, not a physicist.
     
  8. Iain Aschendale
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    Iain Aschendale Contributed Member Contributor

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    Yeah, I was trying to work out the math myself, but got lost in a whole bunch of petajoules and scientific notation. I want something that's in the realm of realism, doesn't need to be "The Martian" good, but not Star Wars either. More study, I guess.
     
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  9. newjerseyrunner
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    newjerseyrunner Contributing Member

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    Easily calculable. The impact that wiped out the dinosaur has been calculated to have had about 4.2e25 Joules of energy. I'm omiting the units below to make it easier to use, but they're all SI units.

    5% the speed of light is 14989622.9 m/s.
    Kinetic energy = (mass * velocity ^ 2 ) / 2.
    4.2e25J = (x * 14989622.9 ^ 2 ) / 2.
    4.2e25J = (x * 2.2e14 ) / 2.
    4.2e25J = x * 1.1e14.
    x = 4.2e25J / 1.1e14.
    x ~ 381 billion kg.



    The space shuttle's mass was 2 million kg, so no, it'd have to go way faster. Let's figure out how fast the shuttle would have to go in order to create such an impact. As long as it's below about 90% the speed of light, we can trust our calculations without having to invoke relativity equations.

    4.2e25J = (2e6 * v ^ 2 ) / 2.
    8.4e25J = 2e6 * v ^ 2
    v = sqrt(8.4e25J / 2e6)
    v = 6,480,740,698 m/s
    Crap. That's way over the speed of light, Newtonian physics isn't capable of solving this problem. @Iain Aschendale, I think this is why you were unable to do the math yourself. Into the special relativity equations we must venture.

    KE = (m * c ^ 2) / sqrt(1 - (v ^ 2 / c ^ 2))
    (m * c ^ 2) / KE = sqrt(1 - (v ^ 2 / c ^ 2))
    ((m * c ^ 2) / KE)^2 = 1 - (v ^ 2 / c ^ 2)
    ((m * c ^ 2) / KE)^2 = 1 + -(v ^ 2 / c ^ 2)
    ((m * c ^ 2) / KE)^2 - 1 = -(v ^ 2 / c ^ 2)
    ((m * c ^ 2) / KE)^2 - 1 = -v ^ 2 / c ^ 2
    (((m * c ^ 2) / KE)^2 - 1) * c ^ 2 = -v ^ 2
    sqrt((((m * c ^ 2) / KE)^2 - 1) * c ^ 2) = -v
    v = -sqrt((((m * c ^ 2) / KE)^2 - 1) * c ^ 2)
    v = -sqrt((((2e6 * 299792458 ^ 2) / 4.2e25)^2 - 1) * 299792458 ^ 2)
    v = 299789712 m/s.
    v = 0.999991c

    Wow, the space shuttle was simply too small. I'll be honest, I was not expecting it to have to be so fast. I really thought Newtonian math would be enough and it wouldn't even be close to c.




    The concept is perfectly sound though, a rod of titanium the size of a telephone pole if driven into the ground from say the orbit of the moon, would impart more kinetic energy than a nuclear bomb.
     
    Last edited: Jan 12, 2017 at 5:17 PM
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  10. zoupskim
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    zoupskim Contributing Member Contributor

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    I came.
     
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  11. zoupskim
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    zoupskim Contributing Member Contributor

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    I always take ONE thing away from these talks about interstellar war, space travel, and relativity:

    A war in space would destroy reality as we know it.

    Any space craft capable of FTL travel would probably require energy equivalent to several lifetimes of our sun. Our most basic exploration probe would be a WMD, it's arrival in a solar system potentially obliterating moons and throwing off orbits as it warped reality around it, blasted loose Alcubierre particles away from it, or mistakenly opened a new rift in space. Plasma shielding held in a magnetic field to block particles and radiation during space travel? Congratulations! You just altered the magnetic field of a planet. Our arrival to an alien world would be heralded by a sky of titan worms, and the worms would be tornadoes.

    That's not even counting political and social implications. What would we think if an alien little robot with a black hole in it's center for a reactor 'phased' above our planet, downloaded all our media, and began playing the most common form of entertainment back to us in an attempt to communicate? The world would look on in horror as the alien invader projected pornography onto the surface of the moon 24/7 in an attempt to communicate. Our every interaction and moment of life, day and night, forced to exist in the foreground of a massive throbbing dick and a gaping pussy.

    To miss-quote Julia Kelly from Peacemaker. "I'm not afraid of the man who wants 10 nuclear weapons, Colonel. I'm terrified of the man who only wants one Alcubierre drive."
     
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  12. newjerseyrunner
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    newjerseyrunner Contributing Member

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    Maths can have that effect.
     
  13. newjerseyrunner
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    newjerseyrunner Contributing Member

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    An Alcubierre drive as calculated by Alcubierre should have no effect beyond the outer limits of it's bubble. The concept of it is a region of space that's extremely warped inwards, that's contained by another extreme warp in the opposite direction. Beyond that, space should remain perfectly flat. Warped space usually requires a long time to disrupt anything. Gravity is super super weak, the exception is extreme gradients in gravity. An Alcubierre drive powering up may be detectable via a gravitational wave detector, and it may create a minor wake due to quantum effects, but nothing dangerous, even at extremely close distances and extreme energies.

    I hate the concept of magnetically controlled shields. Electromagnetism is not discontinuous like that. EM would also be dumb because it couldn't stop all particles. Most cosmic rays are positively charged, but a high enough number of them are free electrons or antiprotons, both of which will be attracted to something repelling normal protons.

    There are 2 other known forces that are both orders of magnitude stronger than electromagnetism and have self-limiting distance. If SUSY is correct (no evidence yet, but haven't really looked either,) there will be several other forces that will have similar extreme strength and limited range.
     
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  14. zoupskim
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    zoupskim Contributing Member Contributor

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    There's a neat scene in the Forever War by Joe Haldeman where a bunch of humans in power armor are getting overwhelmed by aliens in power armor. The human space ships have all been blown to hell, and the aliens are landing troops around the humans.

    The MC sees that a single human fighter pilot has managed to escape, and is flying away from the planet approaching light speed. He laughs and sends the pilot a message saying basically "I'm glad someone survived the battle." After a while the pilot shows up again, only going FAR faster. He wasn't running, but was flying away to get more speed to use his spacecraft as a missile. He slams his fighter into the enemy side of the planet, the FTL impact causing horrible seismic activity in the midst of the enemy, giving the humans a chance.

    In addition to being a brave sacrifice, it's just a neat use of relativity as a weapon. It's also kind of scary, as it shows how much damage can be done when simple things like mass and velocity aren't a limitation anymore.
     
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  15. newjerseyrunner
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    newjerseyrunner Contributing Member

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    A relativistic impact would likely not actually strike the surface, it would air burst. The second it entered the upper atmosphere, almost all of that energy gets turned into heat. that would go off like a bomb of unimaginable power.

    The shockwaves would boil away a huge chunk of the atmosphere and probably melt part of the crust as well. As the energy enters the crust, it'd certainly cause seismic activity.

    The really cool thing is that the energy levels are so extreme that you can't even say that the it would vaporize, vapor is so far below this energy level it's not even funny. I'd call it more annihilation.

    The actual mechanism that all of this energy works would be the collision of atoms at that speed melts them. Not melting the way you're thinking like ice turning to water, but the atoms themselves will melt into degenerate matter. Once it's cooled enough, that'll reform into equal quantities of matter and antimatter, which instantly turn into gamma rays. The gamma rays are absorbed by the planet and heat it up. Also coming out of the degenerate matter would be micro black holes. Those will travel into the planet. Micro black holes are too small to gather material and get bigger so Hawking radiation leaks quickly. They explode with way more power than any nuke in again, gamma rays. Those would decimate the planet from the inside, but the majority of the explosion comes from friction and antimatter.

    An asteroid impact is entirely friction heat. So although it's the same total energy, the energy density means the core of the explosion gets close to the upper limit of our understanding of QM.
     
    Last edited: Jan 12, 2017 at 11:50 PM
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  16. Cave Troll
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    Cave Troll Round and round, spiraling into madness they do. Contributor

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    Too bad for you two. I have a hot math teacher friend, but she is married. :p
     
  17. newjerseyrunner
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    newjerseyrunner Contributing Member

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    Thanks, but I'm married too, so not interested. :p
     
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  18. Iain Aschendale
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    Iain Aschendale Contributed Member Contributor

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    Damn.

    And thanks very much for doing the math, even though it just shot my story to pieces. I was hoping to do a "one shot, one kill" interstellar war with a nearby (<20 light years) civ launching a kinetic kill munition at a "reasonable" velocity (measurable as a low two digit percentage of c). Something as surface-plausible as an ice bullet from a sniper rifle, in other words, but if I have to start adding multiple zeroes to the mass of my projectile, it just ain't gonna work.

    Back the drawing board.
     
  19. newjerseyrunner
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    newjerseyrunner Contributing Member

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    I think you can still do this. Use the derivations I calculated and put in other numbers.

    At 5% c, the shuttle had about a thousandths the energy you need to cause an excitiction level event. That's still 1e11 times more energy than a nuclear bomb. It'd still be civilization ending. It'd still vaporize part of the atmosphere and light fires over most of the planet.
     
    Last edited: Jan 13, 2017 at 1:02 AM
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  20. Iain Aschendale
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    Iain Aschendale Contributed Member Contributor

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    I could work with that, I'll take a look, thanks!
     
  21. newjerseyrunner
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    newjerseyrunner Contributing Member

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    Also, the shuttle is actually quite small. It has to be to launch from the surface but if you launch from space you can build a huge ship, there are tons and tons of asteroids to mine for that. Couldn't you just strap an engine on an asteroid itself? The one that hit us 65mya was not that big relatively speaking and it was going at oribital speed, not relativistic. I'm fairly certain The Enterprise was a thousand times the mass of the shuttle, easily.
     
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  22. zoupskim
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    In a sci-fi short I wrote a rescue ship responds to a distress call from two space fleets fighting each other. The crew of the rescue ship finds the fleets obliterated, with the two flagships perfectly nose to nose, thrusting endlessly at each other, the crews of each locked away in the emergency areas.

    The rescue crew learns from both flagship computers that the two fleets detected and began firing at each other at approximately the same time. Since they were in the middle of space, and the fleets were roughly the same compositions, each inflicted the same sort of damage to each other at roughly the same rates. With no real tactical or strategic options besides just blasting away at each other, since it's freaking SPACE, they just blew each other away until just the flagships were left. Both admirals decided, at the same time, to try a new, never-before attempted tactic. They rammed each other, at the same time.

    The rescue crew ends up rescuing both flagship crews, but makes a point to not tell them about each other until everyone's calmed the heck down.
     
  23. newjerseyrunner
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    newjerseyrunner Contributing Member

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    Well like I said, the shuttle is relatively small. It's by far the biggest space vehicle we've ever had, but every inch of it was designed with weight in mind.

    It would not be comfortable or livable for much more than the regular crew. I think a mars ship will be at lease 50 times more massive and an interstellar ship could easily be 3 billion kg.

    I like science so I like this stuff, but considering we're on a writing forum, you could simply omit the details. You are within an order of magnitude or so. That's perfectly reasonable for sci fi for even the most nitpicky fan. You'd only get into trouble if you give specific numbers, because then you give people like me the tools to solve the equations. From the equations alone and the range I'd estimate, I'd conclude that your physics is reasonable.
     
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  24. Lifeline
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    Lifeline The Dark - not in Wonderland Contributor

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    I got instantly transported back to "Trice upon a time" (Hogan). It's been a long time since I read that book, but I found - and find - that concept real cool. I don't' know much about space/black holes and it never occurred to me that he was incorporating an existing physical principle in his story. :supercool:
     
  25. newjerseyrunner
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    newjerseyrunner Contributing Member

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    “Our imagination is stretched to the utmost, not, as in fiction, to imagine things which are not really there, but just to comprehend those things which are there.” - Richard Feynman

    To be clear, micro black holes are theoretical. They are logically consistent with everything we know, but we've never seen or made one. We aren't capable of making one yet and places where they should be made naturally are so violent anyway that if they were there we wouldn't be able to see them.
     
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