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What is touching

  1. Jul 6, 2009 #1
    If you touch your fingers together, what exactly is touching? When you touch your thumb and your index finger together, you feel them touching, but on a microscopic level, is anything really touching? If you somehow looked at all the atoms that are closest to each other from each finger, how close would they be?
  2. jcsd
  3. Jul 6, 2009 #2
    No, probably nothing is 'touching'. In fact, it's very hard to even define 'touching' on the microscopic level, since every elementary particle is in fact a wave or wave packet, and is in general smeared out over all space. So, in a sense, all particles are touching each other. Of course, the wavefunctions of two particles only 'feel' each other if they are very very close.

    What you feel when you touch your fingers together is the electric repulsion between the outer electrons of the atoms in one finger and those in the other finger.

    I'm not sure how close they would be, but in microscopic terms, probably a large distance apart!
  4. Jul 6, 2009 #3

    D H

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    Staff Emeritus
    Science Advisor

    On a microscopic scale, still "touching". You have to go down to the molecular scale before the concept of "touching" starts to become a bit meaningless.
  5. Jul 6, 2009 #4


    Staff: Mentor

    I believe on a molecular or atomic scale that touching is a combination of electric repulsion and the Pauli exclusion principle, but I don't have any references to back that up.
  6. Jul 6, 2009 #5

    I concur!
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