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  1. #1
    or TizYou?
    TizMe's Avatar
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    Is the light on, or off?

    Here's a Friday test for you.

    Its now approx 7:25 pm in Singapore and is starting to get dark.

    At exactly 7:30 pm, I will turn my light on. But after a further 5 minutes, I will turn it back off.

    Then after an additional 2.5 minutes, I'll turn it back on, and then after an additional 1.25 minutes, I'll turn it back off.

    Continuing on this way, in every interval after that, half of the previous interval, I flick the switch again.

    So my question is:

    At exactly 7:40 pm, is the light on, or is it off?

  2. #2
    Gohills flip-flops wearer
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    Training for the art of self masturbation is a process full of these questions. There is no shortcut. Wax on. wax off.

  3. #3
    Eric
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    it is off

  4. #4
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    50 50 guess ....i guess

  5. #5

    R.I.P.


    dirtydog's Avatar
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    it is being switched between being on or off.

  6. #6
    Eric
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    Quote Originally Posted by Nawty
    50 50 guess ....i guess
    Thats what I reckoned

    Quote Originally Posted by dirtydog
    it is being switched between being on or off.
    Must be off - fuse has blown

  7. #7
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    Singapore had a blackout that night

  8. #8
    Member Mad Hatter's Avatar
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    Quote Originally Posted by TizMe View Post
    Here's a Friday test for you.

    Its now approx 7:25 pm in Singapore and is starting to get dark.

    At exactly 7:30 pm, I will turn my light on. But after a further 5 minutes, I will turn it back off.

    Then after an additional 2.5 minutes, I'll turn it back on, and then after an additional 1.25 minutes, I'll turn it back off.

    Continuing on this way, in every interval after that, half of the previous interval, I flick the switch again.

    So my question is:

    At exactly 7:40 pm, is the light on, or is it off?
    Hmm... Sounds very much like a Zeno's type paradox - specifically if I recall it is Thompson's Lamp. So so long ago since I did this sort of stuff - then I discovered beer.

  9. #9
    The Pikey Hunter
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    You never get to 7:40

  10. #10
    disturbance in the Turnip baldrick's Avatar
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    so why were there 2 five minute intervals at the start of this sequence, and then the next intervals were half of the previous ?

    I predict you will have a sore finger.

  11. #11

    R.I.P.


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    I bet he didn't even turn his light off after he turned it on at 7.30pm

  12. #12
    Dan
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    It turns out that space-time is granular so there's a limit to the amount of subdivisions you can do - the paradox doesn't work out.
    Last edited by Dan; 31-07-2009 at 08:16 PM.

  13. #13

    R.I.P.


    dirtydog's Avatar
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    I also bet that at 7.30pm this evening mr brown will turn his light on, then after 5 minutes will turn it off, then he will try to remember what the timing was and never know whether the light would be on or off

  14. #14
    Eric
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    Quote Originally Posted by dirtydog
    I also bet that at 7.30pm this evening mr brown will turn his light on,
    It doesn't get dark here till 9.30pm so that's out of the equation

  15. #15
    How Dare You!!
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    The tortoise by a hare's whisker

  16. #16
    Thailand Expat
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    My water and fai bill for a month never costs less than 475 or more than 575 whatever I do. It's a one of those mysteries of life

  17. #17
    Pedantic bastard
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    Quote Originally Posted by TizMe View Post
    Here's a Friday test for you.

    Its now approx 7:25 pm in Singapore and is starting to get dark.

    At exactly 7:30 pm, I will turn my light on. But after a further 5 minutes, I will turn it back off.

    Then after an additional 2.5 minutes, I'll turn it back on, and then after an additional 1.25 minutes, I'll turn it back off.

    Continuing on this way, in every interval after that, half of the previous interval, I flick the switch again.

    So my question is:

    At exactly 7:40 pm, is the light on, or is it off?
    My answer is:

    Academic Answer: Thats an exponentially decaying curve and a "pure" solution can't be reached.

    Realistic Answer: Off. Because after doing the on-off-on thing three times, you got bored and went out for a beer.

  18. #18
    watterinja
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    Quote Originally Posted by TizMe View Post
    Here's a Friday test for you.

    Its now approx 7:25 pm in Singapore and is starting to get dark.

    At exactly 7:30 pm, I will turn my light on. But after a further 5 minutes, I will turn it back off.

    Then after an additional 2.5 minutes, I'll turn it back on, and then after an additional 1.25 minutes, I'll turn it back off.

    Continuing on this way, in every interval after that, half of the previous interval, I flick the switch again.

    So my question is:

    At exactly 7:40 pm, is the light on, or is it off?
    It is OFF... even though the switch is ON...

    You broke the darned thing with all your fiddling.

  19. #19
    Thailand Expat
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    I'll try that next Friday and will then tell you...

  20. #20
    Thailand Expat
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    the hare can never win,the race never finish,facts, all can be proved to be true, i think so the light is allways on or allways off, that clears that up then,

  21. #21
    Cenosillicaphobiac
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    Get some proper disco lights, then you wouldn't have to keep flicking the switch all bloody night.

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