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Chronon & Planck's Time

  1. Sep 21, 2003 #1

    Nim

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    What is the difference between a chronon and planck's time? A few websites said they were the same thing. But other websites showed planck's time as being smaller than a chronon. And those websites didn't always agree on how small planck's time or a chronon is.
     
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  3. Sep 21, 2003 #2

    marcus

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    One way to approach this question is to ask what has traditionally usually been meant by "Planck time"

    Planck proposed a set of natural units in 1899 to a meeting of the Prussian Academy and the time unit he proposed was
    for practical purposes the same as what is called "Planck time" today----about 0.539 E-43 second.

    For over 100 years the Planck time unit has been this.

    What the "chronon" is must depend on whatever writer is talking. It is not a well-established traditional thing, so could mean anything someone wants it to mean. The basic string theory scale is not solidly nailed down so if there is a "chronon" in that context it could be drifting around changing from author to author.

    Here is how to remember Planck units:

    Memorize what the area is and get all the rest from that.

    The area is hbar G/c3

    Therefore the length is sqrt(hbar G/c3)

    The unit time is how long light takes to go unit length so it equals unit length divided by c. Or you can divide by c2 inside the square root and get

    Planck time unit equals sqrt(hbar G/c5)


    Since Planck time is 0.539 E-43 second, if you multiply by E45 you get 53.9 seconds which is on same scale as a ordinary minute.

    So next time someone on telephone says "please wait a minute. I put you on hold for a minute" remember that this means

    E45 Planck time units, or maybe you like it better written

    1045 Planck time units
     
  4. Sep 22, 2003 #3

    Nim

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    Thanks for the answser.

    This isn't a physics question. But how do you make those floating numbers like that 45 you have by the 10?
     
  5. Sep 22, 2003 #4

    marcus

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    A2 is written like this (but with the spaces removed)

    A[s u p]2[/s u p]


    subscripts are written like superscripts except you say "sub"
    instead of "sup"

    if you want to see how anyone made a math symbol they wrote in their post, click on "quote" below their post AS IF you were going to reply and wanted to quote them in your reply-----you can look at how they typed stuff and you dont have to reply unless you want----you can just back away
     
  6. Nov 2, 2004 #5

    Mk

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    What are E and G?
     
  7. Nov 13, 2004 #6
    E45 just means 10^45
    G is the gravitational constant
     
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