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Rigid Poles and Faster Than Light Communication

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3 comments to Rigid Poles and Faster Than Light Communication

  • Fergus Gallagher

    I am reminded of an old “paradox” where a pole-vaulter runs at near light speed into a garage. When the far end of the pole hits the back of the garage, the door will automatically close.

    In the runner’s rest frame, the garage will be relativistically contracted and it seems he will never get in on time. But in the garage’s rest-frame, the pole is really short and will fit in easily.

  • Mark

    This very question reminds me about the ‘troll physics’ meme. This problem popped up in the 2nd link.

    I really adore these comics. Sometimes they take you off guard.

    Someone even showed it to a prof about it.

    My favorite is of course winning the lottery by looping two black holes :p (last link)

    1. http://knowyourmeme.com/memes/troll-science-troll-physics

    2. http://knowyourmeme.com/photos/74360

    3. http://www.urlesque.com/2010/10/25/i-showed-troll-physics-comics-to-a-physics-professor/

    4. http://i.imgur.com/Hj0va.png

  • klox

    I used to enjoy solving those simple kinds of relativity problems in my undergrad physics classes. My professor used to frame it as ovens and relativistic pizzas.

    As far as faster than light communication is concerned, wikipedia has some nice summaries. I particularly like the idea of shining a laser across the sky. If you go from one horizon to the other, the laser is clearly moving faster than the speed of light. But you can’t communicate by moving that spot with someone. An observer would have to simultaneously be at both spots in order to get faster than light communications.

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