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Touching At The Atomic Scale

  1. Jun 18, 2014 #1
    I know this is a very common question but I've been seaching in forums all the time and couldn't find a clear answer. So quantum physic say that we can't actually "touch" anything because of our atoms( we're all made of atoms and they repel each other). correct me if I am wrong,please.. atoms indeed can't touch each other,
    so does that mean that people(who are also made of atoms) can't actually touch each other either? for example if we hug someone we don't actually hug him? Or don't I touch my keyboard now ? Just examples, can't think of something else.
    I am very curious about that, and I would appreciate an answer from someone that knows about this subject. thanks!
     
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  3. Jun 18, 2014 #2

    adjacent

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    Yes, technically, we do not touch each other. It's our brain playing the game here.
    If you feel a force acted on your body, the brain detects this and "thinks" something is touching us
     
  4. Jun 18, 2014 #3

    phinds

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    Actually, it depends on how you define "touch". As adjacent says, if you want to be technical and get to the atomic level, atoms don't touch each other but I don't think that has anything to do with the normal human meaning of the term, which we associate with a macro level.
     
  5. Jun 18, 2014 #4

    ZapperZ

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    I'm not sure what you had done and found in your search, but I did a quick search and found these:

    https://www.physicsforums.com/showthread.php?t=662340
    https://www.physicsforums.com/showthread.php?t=458757

    Did you read through them? If you did, then you'll see that a common theme in those discussions is the DEFINITION of what is meant by "touch". If you do not have a clear definition of what you mean, then you will get responses by members who have their own definitions of it, and you'll end up with a jumbled of answers.

    Zz.
     
  6. Jun 19, 2014 #5
    I define "touch" with the normal human meaning as you said. What we experience everyday actually :) For example, I grab my iPhone, I sit on the chair, I hold my laptop's mouse,I hug my cat / my little brother,etc. I've heard many people saying that all these are illusions and we don't actually do anything of what I've described. I can't think of more examples now. I am sorry if I'm still innacurate
     
  7. Jun 19, 2014 #6

    phinds

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    Trying to mix scientific and normal-English meanings of words is often a waste of time. They are "right" at a micro level but so what? If you were to tell an scientifically illiterate bush tribesman that he can't actually "touch" anything he'd think you were crazy. Is he really wrong?
     
  8. Jun 19, 2014 #7

    Dale

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    Then, by that definition, clearly we can and do actually "touch". Every moment of every day you obtain first-hand experimental confirmation of the fact.
     
  9. Jun 19, 2014 #8

    ZapperZ

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    Then you've answered your own question. We DO "touch", in the pedestrian meaning of it. Which now makes we puzzle over why you would ask such a question in a physics forum, since this really isn't a physics question.

    Zz.
     
  10. Jun 19, 2014 #9
    In order to say that atoms don't touch, you would have to claim that no part of one atom is ever at a zero distance from a part of another atom. Under normal conditions, atoms are surrounded by electron shells, so the parts that would be touching would be electrons. Electrons are effectively point object, with a radius of approximately zero. So for two electrons to touch, they would have to be essentially superimposed on each other to an incredible precision. They are also charged. So, for a multitude of reasons (especially one I haven't mentioned), that can't happen.

    But, the scenario above is fictitious. The electrons aren't at specific locations, so to define touching the way we did presumes a condition (specific location) that does not exist. People who claim that atoms do not touch are making valid points (no pun intended), but are doing so by subtly creating a fictional scenario.

    At this level of physics, a more solid definition of "touching" would be to look at how much of an effect each electron cloud was having on the other and picking some threshold that would be considered a "touch".
     
  11. Jun 20, 2014 #10

    Vanadium 50

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    .Scott, why are you bringing in yet another definition of "touching", one that differs from the OP's stated one? How can this possibly clarify more than it confuses?
     
  12. Jun 20, 2014 #11
    I was addressing the overall conversation. Some say "shut up and calculate", but for the many who aren't ready to calculate, there is inexact conversation.
    The OP said "So quantum physic say that we can't actually "touch" anything because of our atoms( we're all made of atoms and they repel each other)." So I was describing the kind of definition that you would have to use to make that statement work. My point was that the notion that "atoms don't touch" is inexact. When you get down to the atomic level, there are quantum effects that undermine any common definition of "touching".
     
  13. Jun 23, 2014 #12
    I will try to clarify it as much as I can. When in our EVERYDAY LIVES are in contact with anything, do we feel this thing or we actually feel the repulsive forces ?? Example, when I grab my phone,am I in contact with the phone, or the repulsive forces between my skin and the phone ?? What's that I feel now when I type on my keyboard? the keys actually or the repulsive force between my finger and the keyboard and I think /my brain says that is the keys ? In general do we only feel forces when we grab /press on things ? Because that's what I've heard. By the way sorry for the delayance but I lost my internet connection for some days :)
     
  14. Jun 23, 2014 #13

    Nugatory

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    It's the repulsive forces that you're feeling. There's no such thing as "actually touching" because if you were to magnify the surface of the keyboard keys and your finger enough, we'd see that neither the keys nor your finger has a clear surface to touch. Instead, you could imagine fuzzy boundary regions that resist being made to overlap.
     
  15. Jun 23, 2014 #14
    wish I could magnify it that much so I could see what does actually happen :P
     
  16. Jun 23, 2014 #15

    Dale

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    You say these things as though they were mutually exclusive. Why do you think it is not both "contact with the phone" and "repulsive forces between my skin and the phone"?

    Using the standard everyday definition of "touch", as you mentioned above then the "repulsive forces" are the mechanism of "touch". You do, in fact, touch and you do so by repulsive forces. They are not mutually exclusive, the second is the mechanism of the first.

    It is like asking if you actually hear sound or instead just vibrations.
     
  17. Jun 24, 2014 #16
    Thank you DaleSpam perfect answer ! So if I understand right without the repulsive forces we shouldn't be able to "touch"anything because then we would chemically react with it. (lol) We can "touch" because the atoms can't . Correct ??
     
    Last edited: Jun 24, 2014
  18. Jun 24, 2014 #17
    Doesn't some "spot welding" often occur? That is, don't a few parts of the two surfaces often react chemically and bond, contributing to the frictional "force"?

    Of course, even at this level there is no physical contact. But, you'd be hard pressed to find closer bonds without breaking down to quarks.
     
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