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

Intergalactic Traveling Methods

  1. Apr 10, 2004 #1
    for any science-fiction type interplanetary colonization to take place (i'm talking large scale like Star Wars or Star Trek) we first need a more efficient method of travelling. so, in your opinion, which of the many ideas out there is most promising. Examples are WORMHOLE TRAVELING, the HYPERSPACE or SLIPSTRING thingy, DIMENSION SKIPPING, REALLY LONG VOYAGES ON REALLY BIG SHIPS, etc. (if there are any that i've forgotten please fill me in)

    ~a pondering nerd

    P.S.: should i make i poll?
     
  2. jcsd
  3. Apr 10, 2004 #2

    LURCH

    User Avatar
    Science Advisor

    I should think that travel from one Gallaxy to another would not happen unless some way can be devised to make use of whatever phenominon is behind quantum entanglement. A form of teleportation.

    For interstellar travel within this gallaxy, really long voyages in really big ships seems most probable, as the other methods are not known to be possible, but this method is.
     
  4. Apr 12, 2004 #3

    chroot

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    It's a pity that quantum entaglement, at least as presently understood, cannot transmit any information.

    - Warren
     
  5. Apr 13, 2004 #4
    Until we achieve faster then light travel i dont think anyone is going to bother exploring jack.
    Long space travel just isnt feasable or even worth it because by the time the people got there we probobly would have devised a faster method and overtaken their wasted journey anyways.
    Maybe 200 yrs we'll figure it out...

    Saw on tv some scientist guy says hes actually sent sound waves through time. apparently some quantum wormhole. sounds about as promising as the photon teleportation. next time i mutate into a photon itll come in handy.
     
  6. Apr 13, 2004 #5
    By quantum entanglement, I assume you mean quantum inseperability?

    It'd be amazing to have such a system across the universe! I'm guessing that one person would download himself to the quantum inseperability/entanglement hub, and be created somewhere else. The advantages of this would dwarf ordinary (light-speed limited) teleportation; Both trips are instantaneous to the 'loader, but the Q-S/E method is truly a to b stat.

    Over and out.
     
  7. Apr 13, 2004 #6
    Why not, if I may ask? My understanding of this subject is very limited to say the least, but I was under the impression that quantum entanglement means that changes to one of two entangled quantum systems will instantly be reflected in the other system. So why can't this be used to transmit information? Are you saying that it is technically impossible at the moment, because of our limited technology, or that it is not theoretically possible and never will be?
     
  8. Apr 13, 2004 #7

    selfAdjoint

    User Avatar
    Staff Emeritus
    Gold Member
    Dearly Missed


    It's an importaant point that quantum mechanics does predict the entanglement but also does not allow information to be sent using it. The real handicap is that any observation of either particle breaks the entanglement. So if you twiddle one of the paricles to send a bit, the entanglement is then broken and you can't do any more with that pair. But at the other end, the measurement of the (now unentangled) other particle can't tell if it was originally in one state ot the other. It takes two observations to do that.

    It's only "after the fact" that you can collect statistics on many pairs and observe that the states of the separated particles are more correlated than classical physics would predict.
     
  9. Apr 13, 2004 #8
    Gravimetric Engines very well could get up to near light speeds so fast that the travel is near instanteous aboard the ship, but of course outside the ship time would progressse normally :(.
     
  10. Apr 13, 2004 #9
    I realize that once you "read" the information you break the entanglement, but is it still possible to send information? If we just want to send the information of one bit, could we? And then to send larger blocks of information you would need more entangled system, but theoretically is it possible?
     
  11. Apr 13, 2004 #10

    Nereid

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    You may have the tiniest inklings of what might, in time, become a cool way to transmit information. Why not take the time to develop the idea further? Describe, in some detail, how you in Israel, on planet Earth, can transmit information to my twin, on an Earth-look-alike planet, circling a G-type star in M31?
     
  12. Apr 13, 2004 #11

    selfAdjoint

    User Avatar
    Staff Emeritus
    Gold Member
    Dearly Missed

    Nereid and Chen,

    How do you tell at the far end which particle switched? You get a random spread of (let us say) spin orientations over zillions of particles (i.e. one end of zillions of pairs). Somewhere in that white noise is a bit, but where?

    I used to think you could line up all the pairs to spin along some preselected axis. But that is a measurement and destroys the entanglement. There is a theorem that says you can't amplify a given spin orientation, i.e. take one pair and produce zillions of copies (or even one copy) spinning the same way. So the pairs you are given are randomly oriented.

    Suppose as someone here has suggested you arrange a filter that blocks all but one orientation. We can think of it classically as a narrow gate; any particles spinning up or down with respect to the gate will pass and any other particles will be blocked, giving us a mono-oriented beam. We can send a bit by destroying that orientation for one particle which automatically also destroys it for the entangled other. These randomly oriented particles would stand out in the mono-oriented background. Trouble is, I am pretty sure that in the quantum world, the initial filtering would count as a measurement, even on the "passed" particle. I don't have a proof of this but I am pretty sure it's true.
     
  13. Apr 13, 2004 #12

    chroot

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    At the "sending" end of the quantum-entanglement communications link, you cannot control which spin (either up or down) your entangled particle will wind up with. As a result, you cannot control which spin the entangled particle on the "receiving" end of the link will come up as. You can only transmit random bits.

    It'd be a great way to create and transmit a one-time-pad though!

    - Warren
     
  14. Apr 14, 2004 #13
    Are you trying to mock my admittedly limited knowledge on the subject, or what? :confuse: Because if you are, I really fail to see the point.
     
  15. Apr 14, 2004 #14

    Nereid

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    No, and I apologise if it came across that way. :redface:
     
  16. Apr 14, 2004 #15

    Janitor

    User Avatar
    Science Advisor

    Not nearly as exotic as the suggestions above-

    In his Space Odyssey novels, Arthur Clarke was dealing with "mere" interplanetary travel within the solar system. All but two of his human characters were put into some sort of cold-storage state, where their metabolism was slowed down to a crawl. Maybe in a few hundred years there will be technology to do this, but I would imagine it would only be practical for voyages of months, not centuries. I think Clarke's interplanetary vehicle was powered by nuclear fission heating a liquid to plasma and ejecting it at high exhaust speed.
     
  17. Apr 20, 2004 #16

    mee

    User Avatar

    Big ships Long time

    yep. yep. yep.
     
  18. May 2, 2004 #17
    What about sending Morse Code signals FTL? You wouldn't worry about detailed information - either the signal (entangled particle) is sensed or it isn't...
     
  19. May 2, 2004 #18

    selfAdjoint

    User Avatar
    Staff Emeritus
    Gold Member
    Dearly Missed

    No information FTL in quantum mechanics. You have to abandon standard QM to get FTL (such as Bohmian mechanics).
     
  20. May 3, 2004 #19
    That's not nessecarily true. In some cases, quantum effects produce FTL phenomena. For example, squeezed vacuum states and Casimir-type effects (ie, the so-called "zero-point energy") all create negative energy, which can be used in things like the Alcubierre drive or the Krasinov tube, both of which are FTL metrics.
     
  21. May 3, 2004 #20

    selfAdjoint

    User Avatar
    Staff Emeritus
    Gold Member
    Dearly Missed

    Quantum mechanics is not yet mated to general relativity, which is where the Alcubierre solution of Einstein's equations has its being. The use of the Casimir effect to meet the negative energy requirements of Alcubierre is purest speculation. Zero point energy is also. There is no true transfer of information FTL within proper quantum mechanics.
     
  22. May 3, 2004 #21
    Perhaps I should have said standard model physics. Squeezed vacuum state experiments have verified that negative energy can be produced, and metrics like Nan Den Broeck's (sp?) solution demonstrate that it is possible to utilize this energy for FTL travel.

    Nevermind that it requires energy densities of about T^00=-6.6*10^93 kg*m^-3, or that such energy densities would be blown apart almost instantly, or that most theorists now beleive negative energy cannot be isolated from the positive energy required for it's creation.

    The scariest thing about intragalactic travel methods, I think, is that any method of quickly travelling about the galaxy inherently involves a device which can utilize and manipulate large amounts of energy in concentrated form over relatively brief periods of time; they are inherently weapons of mass destruction. No talk of species maturity here: a single nut with control over negative mass on a solar scale could destroy a planet. A frightening thought.
     
  23. May 3, 2004 #22

    selfAdjoint

    User Avatar
    Staff Emeritus
    Gold Member
    Dearly Missed

    Could be the answer to Fermi's question: Where are they?
     
  24. May 3, 2004 #23
    Well, we sure as hell aren't the only life in the entire universe. The most likely reason we've not heard anyone is because intelligent life is sparse, and we've only just achieved the power to communicate beyond our planet. (I.E. television/radio) Sentient life might use a different method of long-distance data transfer, such as lasers. Such communication is relatively silent, having little or no leakage over distance.

    For near-luminous to super-luminous travel, you have to figure out how to reduce or control your inertia. Using negative matter, extracted from some sort of Casimir engine, would reduce your virtual mass slightly. With less inertia, you can accelerate faster. Having exact equal amounts of matter and negative matter could let you accelerate to your exhaust speed instantaneously, with no harmful affects. Only until you try to go faster does inertia catch on and increase it's effect. It doesn't really matter; I'm assuming that the Casimir engine would be carried along. Therefore, you can create as much exotic matter as you'd like, just to unreplenish your virtual mass.

    Over and out.
     
  25. May 5, 2004 #24
    They're talkin, but we ain't hearin?

    Re: Fermi's question - "Where are they"

    Just two of many possibilities:

    1) FTL communication of ANY kind simply isn't possible. It's like trying to come up with a perpetual motion machine. No matter HOW long ANY culture has to advance its technological expertise, a thousand years, a MILLION, it doesn't matter. Turns out FTL communication of ANY kind just isn't possible in this universe, and it never will be.
    In which case...

    It's so G.D. expensive to build pretty much any kind of transmitter with the power to send messages over long enough distances to get to anyone who could possibly be listening, while still delivering a strong enough signal on the receiving end to be detected let alone understood above b.g. radiation, that no one ever dedicates the effort to doing it.

    It takes SO many THOUSANDS of years for messages traveling near light speed to make the trip that it's just plain flat out useless as any form of "communication", and as a result, again, nobody bothers trying it on the scale required for anyone to actually be able to pick it up against background radiation over the distances involved.

    Somebody out there DID try it, for over nine thousand years before giving up, but the signals they sent either haven't gotten here yet, or the last signals sent passed our planet by two thousand years ago, so we missed it.

    2) FTL communication isn't just possible, but our entire universe is awash in a thick sea of FTL communications between countless interstellar communities, but NOBODY is idiot enough to try using electromagnetic radiation as a carrier due to it's inherent limitations, so, since we aren't even aware of whatever the hell physical phenomena are used to do the trick, we aren't hearing all the gabbing going on all around us.
    I.e., while we're still sending up smoke signals modulated by an ox hide blanket over a burning log, (and naturally watching the horizon for someone else's smoke signals), everyone else is using the equivalent of digital satellite communications to send and receive their equivalent of everything from I Love Lucy re-runs, to billing information and BBS rants, that our current level of technology is simply unable to detect in any way at all.

    Monsters
     
  26. May 5, 2004 #25

    selfAdjoint

    User Avatar
    Staff Emeritus
    Gold Member
    Dearly Missed

    Fermi was great at back of the envelope calculations. One of them is that if it takes, say, 1000 years on the average to travel from one inhabited star system to another, and you send out self propagating robots ("von Neumann machines"), then in only a couple of million years, an eyeblink galactically, you could visit every such star system in the galaxy. So the robots, at least, should have beeen here.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook