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Thread: Time travel in a centrifuge?

  1. #1
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    Time travel in a centrifuge?

    Someone over on a writign forum posted this question, and I know it won't work, but I don't know why it won't work.

    His idea has two parts. Part one is to fly around the Moon, Earth, or Sun fast enought to start a time dialtion effect. I know why this won't work. Escape velocity would be reached long before any dialtion would be noticed.

    Part two was to put the people on the ship in a centrifuge and spin them so fast that it makes up the difference and allows time to fly by. This is the part I want to understand how to explain.

    For the simplicity, let's forget the orbit the sun bit and put the ship on a straight path to somewhere at 0.5c.
    I figure there are two ways to rotate the crew compartments. The axis can be perpendicualr to the line of travel, in which case the forward and backward motion relative to the ship will cancel out.

    The other is that the crew cabins spin on the same axis as the line of travel, so they would be essentuially riding the outer edge of a football (American) or bullet. I want to say that the motion relative to the ship won't change here either, as the head of the crew member and the nose of the ship will always be the same distance from one another, but if the crew compartment is rotating at, say, a curcumference of 100 meters per revolution, the crew member will travel a lot further than the ship for any unit of time. Would the fact that it's a spiral matter at all?

    Finally, if we put it back in orbit and used ion engines to maintain the orbit despite going much faster than escape velocity, would that change anything?

    I "know" it won't work, and by know I mean I don't know it, but I'm sure I'm right. I just don't know why?
    Unless I'm wrong. The why still applies though.

    Thanks.
    I'm Not Evil.
    An evil person would do the things that pop into my head.

  2. #2
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    It actually would work regardless of which direction the rotation axis is. The only "problem" is that it only works for charged atomic particles. Anything more massive than that, and no centrifuge could apply the petagee accelerations required (with charged atomic particles, this is possible using strong magnets).

    Also, even if a centrifuge could apply the petagee accelerations to a human body, that human body would be instantly crushed into atoms.

    Putting the ship in a pseudo-orbit maintained by ion engines runs into two problems. One is that ion engines aren't capable of providing the required gigagee accelerations. Another is that even if they could provide the required gigagee accelerations, they couldn't do so for more than about ten millionths of a second. And of course, a human body subjected to gigagee accelerations would be instantly crushed to paste.

  3. #3
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    You could, just barely conceivably, do the circular acceleration with diamagnetic levitation. But the magnetic field required would be ginormous.
    __________________________________________________
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  4. #4
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    As the centrifuge spins up, the passengers first suffocate,
    then their cardivascular systems collapse and their brain
    tissue gets shredded, then they are turned into chunky
    salsa, and before they can be fully liquified, the centrifuge
    flies apart, having exceeded the strength of the atomic
    bonds holding the centrifuge's material together.

    -- Jeff, in Minneapolis
    http://www.FreeMars.org/jeff/

    "I find astronomy very interesting, but I wouldn't if I thought we
    were just going to sit here and look." -- "Van Rijn"

    "The other planets? Well, they just happen to be there, but the
    point of rockets is to explore them!" -- Kai Yeves

  5. #5
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    You have stumbled onto the 'Relativistic Wheel', about which there is a lot of literature, which is mostly wrong. Essentially, the analysis requires GR, not SR, of the rotating reference frame. It also is physically impossible, except with magnets and particles (think CERN).
    I'm not a hardnosed mainstreamer; I just like the observations, theories, predictions, and results to match.

    "Mainstream isnít a faith system. It is a verified body of work that must be taken into account if you wish to add to that body of work, or if you want to change the conclusions of that body of work." - korjik

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