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Stopping an Atom.

  1. Dec 5, 2006 #1
    From time to time I have random images pop into my head, which are usually pertaining to subjects I have absolutely no knowledge in. Last night a picture of an atom popped into my head. The electrons and nuetrons were spinning, then suddenly they aligned and stopped, followed by a massive explosion. Kind of freaky, I know. So I'm just trying to do some research on this topic.

    I've searched on the Internet, but haven't been able to find any research or theories about stopping an atom. I've seen an article about lasers being used to significantly slow them down in order to be able to get a better understanding of how they work, but nothing on actually stopping it completely.

    Basically, I'm looking for some information on ongoing research/theories and how this would be accomplished and what would happen if an atom were completely stopped. If anyone here has some links to share or just a general interest in discussing it, please do so here. Like I said, I'm not very knowledgable in physics, I suck at math, but I am willing to do research and discuss theories with anyone who is interested.

    Thanks :)
     
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  3. Dec 5, 2006 #2

    Astronuc

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    Re: Stopping an atom

    by changing the fundamental laws of physics.

    Nothing - it would be completely stopped. :biggrin:

    When an atom stops - that would simply imply no translational motion in any direction, but the electrons within the atom would still be moving.
     
  4. Dec 5, 2006 #3

    Claude Bile

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    Electrons cannot move within the atom, as Maxwell's equations say that if they did, they would radiate energy and collapse into the nucleus. An atom in its ground state exhibits no time dependance, thus it is for all intents and purposes 'stopped'.

    This is all owing to the fact that bound electrons behave more like standing waves rather than discrete particles.

    Claude.
     
  5. Dec 6, 2006 #4
    But, if we can apply the De Broglie relation l = h/p to the entire atom, wouldn't this mean that the atom is spread in all space?
     
  6. Dec 6, 2006 #5

    Claude Bile

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    The De Broglie relation relates wavelength to momentum, it says nothing about the wavefunction of the particle.

    Claude.
     
  7. Dec 7, 2006 #6
    Said in another way: if you have a free particle with zero momentum, solving SE, what do you have?
     
  8. Dec 7, 2006 #7

    Claude Bile

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    I think you mean the HUP? :wink:

    Yes, from what I understand, the wavefunction of the particle will be spread in all space if the uncertainty in p is zero.

    Claude.
     
  9. Dec 7, 2006 #8

    DaveC426913

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    Let's make a distinction here between stopping the atom and stopping the various subatomic components of an atom. One is a matter is physically stopping the atom in space, which is what they're doing with lasers, but this has nothing to do with stopping the electrons and neutrons.

    The only way to "stop" a subatomic component is by decay or other way of changing it into a different form of subatomic particle, say, an electron into a positron and a neutrino. But then it stops being a part of the atom.
     
  10. Dec 7, 2006 #9

    Gokul43201

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    I don't get this whole deal about stopping subatomic particles. What's there to stop? In the rest frame of the atom's CoM, the electrons and protons are all stationary.

    As for laser cooling, you use that to slow down an ensemble of atoms - not a single atom.
     
    Last edited: Dec 8, 2006
  11. Dec 7, 2006 #10

    DaveC426913

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    I think the idea is that you could stop the electron and have it crash into the nucleus.
     
  12. Dec 8, 2006 #11
    Are they? They might not necessarily even be in stationary states, let alone eigenstates of position...
     
  13. Dec 8, 2006 #12

    Gza

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    I think the assumption is that there are no time dependent pertubations at work here, so only consider the stationary states. In the case that the electron -is- in a certain state, i dunno, just compute <[x,H]>, where H is the hamiltonian of the electron with the coulomb potential, and make sure it comes out to zero to see if it moves at all (very sloppy, but i hope you get what i'm saying).
     
  14. Dec 8, 2006 #13

    DaveC426913

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    And this answers the OP's question how?
     
  15. Dec 8, 2006 #14

    Gza

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    It was never really meant to, i was just trying to clarify how the poster above me was handling the OP's question. My apologies.
     
  16. Dec 8, 2006 #15
    I apologize if I was unclear in my initial post. I think my question pertained more towards the possibility of stopping the subatomic parts of the atom, not so much as trapping an actual atom in space (which I am under the impression is what the lasers are for).

    I've been doing some research, but I realize that my knowledge in this area is extremely limited. I apologize if this turned out to be a "why is the sky blue?" type of question :)
     
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