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2 physics riddles

We take so much for granted.

Try to solve these two riddles on your own:

  1. How can one prove the earth is round?
  2. How can one prove the earth revolves around its axis, and around the sun?

Answers are here and here.


  1. Ofer Egozi:

    Yes, this is fun. I’m looking forward to the day my kids are old enough to come up with their own genius ideas.
    Problem with many of answers in the links is that they take some other axioms for granted. It really depends who you’re trying to convince. A Foucault pendulum, for example, can easily be explained with a bunch of witchcraft and ghosts stories, rather than earth rotation…

  2. ripper234:

    I’d use Occam’s Razor to choose between the two explanations. Sure, it won’t work on all people equally – some would argue witchcraft is a simpler explanation, or “God move the pendulum in order to fool you”.

    You can’t forcibly convince people that don’t want to be convinced.