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

Mystery Spot illusion explanation

  1. Jul 22, 2009 #1

    How do you explain what you experience there?

    I understand it's all optical illusion. I can explain - people walking on the wall, pendulum swinging at an angle - is just a slant-walled house.

    The thing I could not explain is the relative height difference they demonstrate. The ask 2 people of different height to stand on a beam. Then they swap their position - the taller guy looks shorter and vice versa. The beam is not inclined - they prove it with a spirit level.

    Also, they show a rubber ball rolling upwards in a wooden rail. With a spirit level, they show the wooden rail is not slanted.
  2. jcsd
  3. Jul 22, 2009 #2


    User Avatar

    The house is slanted.
    Last edited by a moderator: Sep 25, 2014
  4. Jul 22, 2009 #3
    I understand the house is slanted and it explains most of the stuff. But they put a spirit level on the beam and the bubble is exactly in the middle.
    Last edited by a moderator: Sep 25, 2014
  5. Jul 22, 2009 #4


    User Avatar

    Probably the beam is level, but the groove where the ball runs is slightly slanted.
  6. Jul 22, 2009 #5
    It is possible to make an object appear to roll uphill if the track the object, such as a ball, changes in width. There was/is an old kids toy from many years ago that used this principle.

    There are two metals rods, equal in length and thickness. They are each attached to a separate hinge or axle, so that the far end, the rods can be moved further apart. The pair of rods are inclined slightly, so that the free ends are lower then the fixed ends. The object of the game was to control the free ends to allow a steel ball to "roll" uphill before falling. The further uphill, the more points.

    How it works is that even the object appears to go uphill, the center of gravity is falling as the width of the rods increase.

    I think it was called Shoot the Moon, and my parents still have it at their place. I will see if I can find when I am there next, though may be some time.

    Found a picture:
    http://img189.imageshack.us/img189/3926/314tfkn5bklss400.jpg [Broken]
    Last edited by a moderator: May 4, 2017
  7. Jul 22, 2009 #6


    User Avatar

    Staff: Mentor

    Wow, that's an old picture! Still has pluto on it... :wink:
    Last edited by a moderator: May 4, 2017
  8. Jul 22, 2009 #7
    and its missing Venus, Uranus and Neptune.
    plus the Moon isn't even on it.
  9. Jul 22, 2009 #8

    Ivan Seeking

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    I remember playing with one of those. My uncle had one.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Mystery Spot illusion explanation
  1. Illusions (Replies: 17)

  2. Mystery Spot (Replies: 17)

  3. Illusions (Replies: 20)

  4. Illusion by Conflation (Replies: 2)