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What is the best scientific method to deep space travel

  1. Jun 9, 2007 #1
    i have a question for your minds to wonder about. i don't know the answer but i would love to hear your opinions or facts if you have any. now i am probably the hugest trekkie a person can be. i love star trek, it is one of the things that got me into science. anyways, what makes Star Trek, Star Trek is the ability to travel in space at speeds faster then light. now i have heard many theories about the concept of warpdrive. one of my opinions is maybe deep space travel is best done when bending space time, or something like an event horizon. i am not an expert on this side of science so i just want to hear what others have to say.
     
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  3. Jun 9, 2007 #2

    Chris Hillman

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    "Warp drives" in the physics research literature

    Hi, tpribb01,

    I have in the past posted detailed critiques, based upon discussion of the notion of "warp drives" in the research literature and upon my own exploration of such models, in the newsgroups sci.physics.relativity, which once boasted say a 20-80 balance between knowledgeable posters and cranks; now the ratio is more like 2-98, unfortunately :grumpy: You can google for those posts, so I won't repeat myself at great length here.

    The key points to appreciate are these:

    1. Alcubierre's model is a valid Lorentzian manifold which realizes some features in common with the fictional warp drive in Star Trek, e.g., people don't fall over inside the Enterprise when the ship accelerates and a "warp bubble" surrounding the ship goes effectively superluminal. The "effectively superluminal" aspect of the motion of this bubble is a global effect which doesn't contradict the fact that no material can travel faster than light. All at the level of Lorentzian manifolds. (I know you don't know what I am talking about, I am just mentioning some technical buzzwords you can ask about here or elsewhere.)

    2. However, this and similar spacetime models called "warp drive models" in the literature are in no sense solutions to the EFE.

    3. In fact, a great variety of objections have been raised in the literature. Probably the most fundamental concern that fact that all known "warp drive models" invoke "warp bubbles" which appear spontaneously and feature energy which moves in what is thought to be a physically impossible manner. There are arguments strongly suggesting that this would be true of any warp bubble, i.e. that warp bubbles are physically impossible "causally". In addition, the energy requirements appear to be prohibitive, and again there are general arguments based upon some obscure corners of QFT suggesting that warp bubbles would be physically impossible on "energetically".

    4. For a few years, there were quite a few eprints exploring the notion of "warp drives". This activity seems to have largely died out, and I think it is fair to say that the current mainstream viewpoint is that "warp bubbles" are physically impossible. There are a handful of dissenters from this viewpoint.
     
  4. Jun 9, 2007 #3

    marcus

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    I would urge you to change the question slightly and think about a variation of the problem:

    what is a practical scientific method to spread earth life to other habitable planets?

    Suppose that, during the next few years, several earth-like planets are found orbiting in the habitable zones of nearby stars (say 10-100 lightyears from us.) Suppose no signs of life are detected, by whatever means are used.

    What methods can you think of to establish earth life on these places, if they resemble earth enough to harbor it?

    Would your first reaction be to call for the invention of a faster-than-light vessel? Or would you consider other approaches to solving the problem?
     
  5. Jun 9, 2007 #4

    Chris Hillman

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    Another question is: what kind of Earth life should we spread? If any? Is it perhaps immoral to deliberately infect other planets with Earthly life forms? Particularly humans? See Alan Burdick, Out of Eden, for a recent popsci book (by a nonbiologist).
     
  6. Jun 9, 2007 #5

    marcus

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    I'll save the moral discussion for another thread, and focus on technical means.

    Mr. Tpribb is asking about method.

    To repeat the question, admittedly any one of us can probably think of ways to do this without needing outside inspiration, and may have read published scenarios as well, but let's take a fresh look and see what we come up with:

    Suppose in the next few years several habitable planets are found at 10-100 lightyear range, with no detectable signs of indigenous life. Can you imagine any practical way to impregnate them with earth life?
     
    Last edited: Jun 9, 2007
  7. Jun 9, 2007 #6

    pervect

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    Do you want "earth life" or "humanity"?

    I can imagine nuclear drives of one sort or another getting us up to a few percent of the speed of light - or possibly solar pumped lasers to drive a light sail. Braking the light sail would be a problem, though, while Forward has described 1000 km Frensel lenses as a possible solution, I don't think that fits in the time frame specified. Possibly a hybrid system - a laser driven light sail, along with some sort of nuclear rocket for braking.

    I can imagine with our current biology getting some sort of earth life to survive the 1000 year trip, but I don't think our biology is good enough to get human life to survive or be able to be recreated after such a journey.

    I think the general key to "practical" interstellar travel will lie in biology, or perhaps in robotics, rather than physics. Forget about beating the speed of light, or even approaching it closely. Plan on spending 1000's of years at a percent or two of c instead.

    I'm also thinking that this thread will fit better in the general discussion forum, so that's where I'm going to move it.
     
    Last edited: Jun 9, 2007
  8. Jun 9, 2007 #7

    marcus

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    Robotics. I am in exact agreement with you here. A robot can exist in a shutdown state for 1000s of years and then wake up and cultivate cellular life. Might even experiment intelligently to find out what singlecell organisms are best adapted to the environment.

    I would like to hear from Mr. Tpribb, though. I would be happy to go away if he does not want people talking about the mere transmission of living organisms to a new habitat.

    It is Tpribb's thread. I just hope he will consider this as a friendly evolution of the problem he posed.
     
    Last edited: Jun 9, 2007
  9. Jun 9, 2007 #8

    Integral

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    One has to wonder if the descents of humans locked aboard a space ship for generations would still be considered humans? What evolution would occur to adapt these beings to live in a steel tube?

    A tree or blue sky would exist only as pictures in the data bases, what meaning would that have to someone 3 or 4 generations from launch?

    I remain convinced that the main task for the next 2 generations is to establish that we can maintain our current state of civilization on the space ship earth. Once we have done that then we can look to spreading the virus we call life to other systems.
     
  10. Jun 9, 2007 #9

    Office_Shredder

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    In 2 or 3 generations, modern civilization won't be.. Just like civilization in the 40''s isn't around today. So I find that to be infeasible at best
     
  11. Jun 9, 2007 #10
    i think traveling at a decent fraction of C is the only answer. the point is not to colonize other planets simply for the sake of spreading our species, the point is to preserve some semblance of our society. like " i want my kids kids to persist " i imagine that is the sentiment. why would anyone care about another group of humans who have absolutely nothing to do with us, what would be the point.
     
  12. Jun 10, 2007 #11

    marcus

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    everyone has their own personal viewpoint
    and an idea of what they'd be willing to pay for.

    I just spent a week in a relatively undeveloped corner of a pacific island, for much of the time snorkling over reef

    I'd be willing to consider part of my taxes going to start fish somewhere.
    You'd have to start algae first, to build up oxygen, I guess. And then some other things: plankton, weed...

    Fish look nice and mind their own business.
    I hope astronomers find a warm water planet where we can eventually plant some fish.

    the robot would know how to do it.
    there would be fish DNA stored digitally in the computer so that if the frozen eggs didn't hatch the robot could reconstruct DNA and start them that way.
     
    Last edited: Jun 10, 2007
  13. Jun 10, 2007 #12

    Ivan Seeking

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    There was some interesting stuff coming from the so called Heim physics that emerged recently, but I don't what has become of this. Allegedly, NASA, the USAF, and the DOD were all experimenting with a Heim physics based FTL drive.

    If not already disproven, "Heim physics" is not proven or accepted as valid. It may all be wrong.
     
  14. Jun 10, 2007 #13
    but the question is why? do we care about fish? do fish want to live on other planets?
     
  15. Jun 10, 2007 #14

    pervect

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    The only advantage of travelling at a large fraction of 'c' is to make the trip shorter for the traveller. It won't make that much difference in the amount of Earth time that a round trip takes, because that velocity is strictly limited by 'c'. So even if you had a gamma factor of 10:1, your round strip time would be limited by the distance travelled divided by 'c'.

    It would probably not only be easier to extend people's lifespans than to reach a large fraction of 'c', but there will probably be more effort put into it, because people want to live longer. Having a bit of patience because of longer lifespans (possibly bioengineered longer lifespans) is much easier to imagine than it is to imagine a drive with significant relativistic gamma factors.

    This is assuming we don't blow each other up first, which actually seems like the most probable course of events.
     
  16. Jun 10, 2007 #15

    DaveC426913

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    The word is colonize. And every species has the "right" to ensure its survival.

    Which is one of the pirmary motivators for having a backup humanity.
     
  17. Jun 10, 2007 #16

    Chris Hillman

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    I don't think I really want to pursue this argument, Dave, but

    1. For better or for worse, "every species has the right to ensure its survival" is not a principle recognized in human jurisprudence :wink:

    2. Wise biologists have long recognized that the notion of a (biological) "species" is merely a convenient fiction. Space precludes me from even attempting to explain what I mean by this, but if you are curious, see Ernst Mayr, Population, Species, and Evolution for an extensive discussion of this point. For this and other reasons, I feel that it makes little sense to grant rights to "species", but I would agree that the suggestion that "individuals" (biological or otherwise) should perhaps be granted some rights, is worthy of consideration. In particular, while I might be biased, I feel that software entities should be granted some legal rights.

    Incidental remark: it is a curious fact that human jurisprudence recognizes the rights of individuals, meaning human individuals, without making (AFAIK) any attempt to provide a legal definition of a human being. Biologists say that experience with producing chimeras suggests that producing a human-chimp chimera would not be particularly difficult. This is an experiment which biologists around the world seem to universally deplore, but I tend to think it's inevitable that eventually someone will do it, just because they can. I myself feel this experiment would be unethical, but not much more so than more typical reproduction involving two humans or two chimps.

    Another incidental remark: it is a curious fact that despite the evident economic superiority of states whose citizens are software entities rather than wetware entities, the much vaunted laws of the marketplace have thus far been surprisingly slow to produce examples.
     
    Last edited: Jun 10, 2007
  18. Jun 10, 2007 #17

    Chris Hillman

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    I definitely don't want to pursue this, but the so-called "Heim theory" [sic] lacks the form of a "physical theory" as I understand that word. Rather, it seems to be more like a heuristic for which a tiny minority makes extraordinary and highly suspect claims. It is considered cranky by mainstream physicists. (And the so-called "selector calculus" is a topic which is not recognized as mathematics by mathematicians.) Obligatory warning: Wikipedia articles have been the subject of an endless edit war between proponents of "Heim theory" [sic] and members of WikiProject Physics.

    A general comment: cranks commonly claim that this government or that is sponsoring research into their "theory". These claims never seem to hold up to closer scrutiny. That is, it might be true that some large aerospace organization granted an interview to some crank touting an alleged "inertialess drive", and when this happens it is widely publicized on the crank net. What you don't hear is that the internal report basically said "this guy is a nutcase, end of story". It is also true that various governments have from time to time sponsored some highly questionable "research projects" (the recent case of Roger Shawyer and his EmDrive might be an example), but in these cases, closer examination shows that when usable results were not forthcoming, the grants were terminated.
     
  19. Jun 10, 2007 #18

    pervect

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    If humanity was concerned with its own survival, more people would think like Dave does here. But depressingly, it appears to me that on the whole, humanity is just an abstraction. What we actually have is not an abstract "humanity", but rather a bunch of people, who are mainly interested in the very short term.
     
  20. Jun 11, 2007 #19
    Just as an addon:

    Given something with the mass of the space shuttle at liftoff (including fuel, etc, just to approximate) 2,029,203 KG (4,474,574 LB)

    What do you think our current capabilities, if we dedicated all possible resources, would get us up to in terms of speed toward a distant star.

    Assume money is no issue, using nuclear explosions is no issue, maybe just like : taking all nuclear material and converting it to acceleration energy.

    Then I guess we can split it to inculde slowing down.
    But how fast do you think is possible going "all-out"?


    (oh and just to comment on the rest)
    If sending life to an unpopulated planet the whole eco system would have to be mimicked. for the most part. I'm sure you could be really selective with some research. (A beetle that eats the poo of a fox that catches ground squirrels that eat the beetles.) With alternative sources of plant food that theyre all compatable with slightly. Or you just do all herbivores. But even the plants need bugs, bacteria, algae, all sorts of microorganisms to replenish the soil's nutrients. You would need serious modeling of enviroments given whats known about each organism chosen, and im sure some long experiments to determine side effects.
     
  21. Jun 11, 2007 #20

    Ivan Seeking

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    We had a bit of debate in the Mentors forum about where to put any Heim related information. At the time, no one here had ever heard of it. In the end it was moved to the Beyond the Standard Model forum.

    There were several news articles about this and it seems to be true that all three agencies were looking at it, but as you said, this doesn't give the theory credibility.

    ...on the other hand, even if it worked we would probably never know for decades as it would be classified immediately. :biggrin: I suppose this is why the military dumps a few bucks into long shots from time to time - the potential-pay off justifies the crap shoot.
     
    Last edited: Jun 11, 2007
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