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    Re: Spaceship navigation
    From: Gary LaPook
    Date: 2017 Jan 16, 07:13 +0000



    From: Frank Reed <NoReply_FrankReed@fer3.com>
    To: garylapook@pacbell.net
    Sent: Sunday, January 15, 2017 1:28 PM
    Subject: [NavList] Re: Spaceship navigation

    Gary LaPook, you wrote:
    "Without giving away too much and ruining the movie, we find out that the 120 year travel time is as measured on earth and the ship is traveling at 0.9 C. So the time, as measured by clocks on the ship, runs at about 44% of earth time. "
    Um.... no... no, we don't find that out. The 120-year travel time is clearly intended to be the shipboard travel time throughout the film, right until the very end. There's no "reveal" about speed being 0.9 c, nor anything suggesting that the actual time was reduced. 
    -----------------------------------------------------------------------------------------------------------

    My recollection is that when the guy said that they needed to turn the ship around and go back to earth that he was told that since the ship was travelling at nine-tenths the speed of light it would take longer to turn it around and go back than to continue, kinda like being past the "equal time point" as used for oceanic flight navigation planning.  That is where I got the 0.9 c from. 
    ===============================================================================================================
    Another minor spoiler alert:
    There's a plot point that's semi-science, semi-culture. Our heroine says she planned to spend a year on the colony world, then fly back to Earth so that she can publish a book about her experiences (on Earth, more than 250 years in the future).
    ----------------------------------------------------------------------------------------------------------------------------------------------

    She said it was like doing time travel and going to the future and arriving on earth about 250 years in the future which makes sense that she was talking about 250 earth years into the future. If my recollection is correct, that they were travelling at 0.9 c then 240 space ship years, out and back,  (leave out the time spent on the new planet) would have been 545 earth years, which is not consistent with her statement about 250 years into the future which was more confirmation that they were travelling at 0.9 c and that the 120 years statement meant earth years, not space ship years. If they were actually going at 0.5 c and the 120 years (240 round trip) were space ship years then she would arrive back on earth more than 277 earth years, significantly more than her statement, which again confirms that they were talking earth years (120) not space ship years.  
    ============================================================================
    OK, one plot hole (significant spoiler alert):
    Near the end, they realize that the medical pod --the only one on the ship (bad emergency planning)-- can serve as a temporary "stasis pod" but, oh no, she can't bear to leave him now that she loves her sleazy kidnapper again. So that's that. Wait... wait... wait... They couldn't figure this out? Stick her in the pod, and then thaw her out for Christmas week every year! I think our hero can manage 51 weeks living in luxury with his robot friends with the promise of a week of sex with the hot girl every year. Plus she gets to decide, and she gets her life back! After 50 years of these holiday cycles (before the old goat dies), she'll only be 50 weeks older upon arrival. Problem solved. But no... it's "Hollywood Happy Every After" in a cottage in the woods in the middle of the shopping mall... Beauty and the Beast in spaaaaaace...
    Needless to say, it's just a movie. ;)
    Frank Reed
    ------------------------------------------------------

    I thought of that one too while I was still in the theater and I figured that they could take turns and each age only 45 years on the trip. It wasn't till waking up from my dream the next morning that I remembered the Lorentz transformation.

    gl


       
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