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

Thermal motion of graphite atoms

  1. Jul 13, 2015 #1
    Hi everyone, I've been thinking about the quantum pencil, and I can't quite convince myself that you could perfectly balance a perfectly sharpened pencil even if the uncertainty principle went away. For those who are unfamiliar with the problem, you can read about it here: http://thevirtuosi.blogspot.com/2010/06/how-long-can-you-balance-quantum-pencil.html

    The idea is that the uncertainty principle prevents you from being able to balance the pencil quite perfectly, and it will balance for no more than 3.5 seconds. It seems to me, though, that the thermal motion of the atom at the tip of the pencil's graphite lattice would also make it impossible to properly balance it. Can anyone share their thoughts/provide me with some resources regarding thermal motion of lattice structures?

    Thanks in advance,
  2. jcsd
  3. Jul 13, 2015 #2


    User Avatar
    2017 Award

    Staff: Mentor

    Thermal motion would also make it impossible, right. You could cool it down to absolute zero (not in reality, but an infinitely sharp pencil tip does not exist either) to avoid that. Not with quantum mechanics, but then you are back to the original balancing issue (the calculated uncertainty comes from the thermal ground state in QM!).
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook