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

Why don't objects blend?

  1. Jan 30, 2010 #1
    I know nothing about quantum physics and I have nowhere else to ask.

    What I'm wondering is why there appears to be a "uniqueness" to all objects in the world.
    For instance my pepsi bottle does not blend with my other pepsi bottle, and they will always be self contained objects.
    First I thought that it was just at an atomic level, the objects must be tied together there.
    But then I thought, how are atoms created on the quantum level?
    Why don't two objects of the same atomic structure "blend" together when they meet?
    Why are all objects unique and separate, while the electrons and atoms still remain "glued" to each other to create the object?

    Thanks to anyone who can clear this up.
     
  2. jcsd
  3. Jan 30, 2010 #2
    As far as I know, at the particle scale, when two of the same particle are in proximity of each other, it is impossible to differentiate between their wavefunctions.
     
  4. Jan 30, 2010 #3
    So an object is glued together because the particles are extra close?
    How does an objects particles know it 'belongs' to one particular object?
    And why don't objects blend when they come in contact.

    I guess those are my two questions.
     
  5. Jan 30, 2010 #4

    Mentz114

    User Avatar
    Gold Member

    The atoms that make up the glass of the pepsi bottle are arranged in a way that has the least potential energy. They form a stable bound system because energy is needed to redistribute or arrange them differently. If you supply enough heat, atoms get enough energy to break from the potential that holds them.

    Glass will get softer and softer as the temperature rises. For a crystal like sodium chloride, there is a distinct melting point, when the solid becomes liquid.

    In short, a particle 'knows' it is part of some greater thing because it feels forces holding it in a certain way relative to the other constituents. Thus, two distinct objects cannot merge unless a lot of energy is supplied.
     
  6. Jan 31, 2010 #5
    If your question is about how it's possible for two pieces of material to be brought close together without becoming one, the answer is this process is called cold welding.
     
  7. Jan 31, 2010 #6
    Finally, there is the Pauli Exclusion Principle which is responsible for (among many other things) Degeneracy Pressure which prevents total gravitational collapse of White Dwarfs, Neutron Stars, etc.

    "Blending" doesn't occur because of forces (EM, Nuclear, etc) and effects that are present at energy levels below that generated by the heat/density of the VERY early (as in microseconds) universe. Then at the extremes when it's "Gravity vs. Quantum Effects" The Pauli Exlusion Principle (MAJOR SIMPLIFICATION INCOMING) which can be considered the ultimate "anti-blender" for matter only breaks down within the Event Horizon of a Black Hole (assuming they exist as described by Hawking et al).

    In theory, within a BH even Degeneracy Pressures are overcome and a gravitational singularity forms. At that point everything would lose individual identity, which may or may not lead to the possible Information Paradox.

    EDIT: Edited for "non" in the exlusion principle. Sorry!
     
    Last edited: Jan 31, 2010
  8. Jan 31, 2010 #7

    SpectraCat

    User Avatar
    Science Advisor


    Ok, I have seen this a couple of times on here now ... what is the "pauli non-exclusion principle"? Does that somehow refer to bose-einstein statistics? A google search on the term was relatively fruitless (most of the hits referred back to PF). Also, at the subatomic level, isn't all matter made up of fermions? So wouldn't the regular exclusion principle hold (as you seem to say below)?

     
  9. Jan 31, 2010 #8
    Wikipedia has a shockingly decent entry on the subject. http://en.wikipedia.org/wiki/Pauli_exclusion_principle

    However, to be simplistic it just says you can't have two 'things' with identical values occupying the same coordinates in a quantum system anymore than you can have two classical objects occupying the same space at the same time. That is generalized to a number of situations that are very common.

    Remember, a White Dwarf is mostly a soup of free electrons and atomic nuclei. If gravitational collapse continues, Degeneracy pressure is NOT overcome, but other forces are and the electrons and fused with the protons to form neutrons... aka a neutron star. After that, maybe there are Quark Stars, etc... but the bottom line is that Degeneracy Pressures being overcome = the inside of a BH.
     
  10. Jan 31, 2010 #9

    SpectraCat

    User Avatar
    Science Advisor


    Um .. yeah. It was the NON in your post that was confusing me (I have seen similar language in other threads on PF) ... I am totally down with the Pauli Exclusion Principle for fermions. :wink:

    The only thing I could find relating to any non-exclusion principle has to do with non-exclusion statistics, which seemed to be applied exclusively to bosonic systems in the references I could find with a semi-cursory (~10 minute) online search.

    So, that was the backdrop against which I was asking my question.
     
  11. Jan 31, 2010 #10
    Ahhh... My bad! Bosons certainly are not subject to the Exclusion Principle, but I don't know that there is a specific NON exclusion principle. My guess is that most places on PF it's just people like me with too much coffee and too little sleep.
     
    Last edited: Jan 31, 2010
  12. Jan 31, 2010 #11
    I'm not quite sure what you're asking about the pepsi bottles. Are you asking why if you smash two pepsi bottles together they don't agglomerate and make one big mass?

    If that's your question, here's my answer:

    That is an inherent chemical property of many substances, just not the pepsi bottle in those conditions. We call the things that "blend" together fluids and the things that don't solids. As for chemical bonding when things touch, there are some things that do that. Those are acids and bases (or pretty much any other spontaneous reaction for that matter). Essentially, the "blended" state has to be in a lower energy state than the seperate object state, with no substantial energy hill to get over. If those conditions are not met, two objects that touch will not do anything.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook