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

Electron crash into Proton

  1. Jan 10, 2009 #1
    Why doesn’t the Electron crash into the proton??
    We know in an H atom the e- is attracted to the + charge of the proton.
    And it wants to get down to the "0 level" orbit.
    But what makes that level zero – or why does e- stop going down?
    Is there another force that counteracts the force of charge trying to pull them together?

    Note: the intent of this thread is potential descriptions of why the electron does not crash into a proton. NOT how QM defines it or that QM can claim that no one can describe it. But how people do try to describe it. So explaining why an idea doesn't work should also be described in Non-QM terms. Everybody already knows that uncertainty and the math of QM does work, we do not need to be reminded.
     
    Last edited: Jan 10, 2009
  2. jcsd
  3. Jan 10, 2009 #2
  4. Jan 10, 2009 #3
  5. Jan 10, 2009 #4

    malawi_glenn

    User Avatar
    Science Advisor
    Homework Helper

    Yes QM explains this very well, why do you want another answer/explanation?
     
  6. Jan 10, 2009 #5
    I think what QM tells us is to "shut up and calculate", but does not really "explain" it
    If you know the answer, why don't you spell it out for us?
     
  7. Jan 10, 2009 #6

    malawi_glenn

    User Avatar
    Science Advisor
    Homework Helper

    then you are perhaps more interested in the philosiphical viewpoint?

    Quantum is the best way (well quantum electrodynamics is) to describe the hydrogen atom and its observables.

    What explanation are you looking for? (or are there several other

    It is like answering the question why does the stone fall to the ground if I realse it from a height? "The law of gravity tells that there is a force acting on the body and make it accelerate down til it hits the ground"

    Quantum mechanics tells you that you alot of things, that the potential of the proton (hydrogen nucleus) and the electron is an operator and one should find the eigenvalues and eigenstates to that operator.

    Quantum mechanics is not just "shut up and calculate", what that quote is saying (R. Feynman ironically) is that one should leave the intutive (newtonian, macroscopic) way to look at physics and instead stay to the formalism and axioms of QM and see what u get.

    "What is REALLY" going on, and why, is a philosophical question.

    You are demanding that quantum phenomenon should be explained in NON QM terms, is that a plausible demand you think?
     
  8. Jan 10, 2009 #7
    Most aspects Newton mechanics is obvious for our brain because it is pre-wired in our muscles: we know how to jump, how to catch objects, we understand spacial/time relationships.

    but QM is not pre-installed in our brain.

    In order to understand 4,10,11,26-dimensional spaces, non-euclidean geometries and QM you need to have more imagination.

    Anyway, what do you mean by "really explain"?
     
  9. Jan 10, 2009 #8

    jtbell

    User Avatar

    Staff: Mentor

    From the Physics Forums FAQ in the General Physics forum:

    Why Don’t Electrons Crash Into The Nucleus In Atoms?

    I'll also point out that in a sense, electrons do "crash into the nucleus" because the wave functions for most orbitals are non-zero at the origin (the nucleus). In some isotopes, this causes the nucleus to decay into another one via a process called (surprise!) electron capture.
     
  10. Jan 10, 2009 #9

    malawi_glenn

    User Avatar
    Science Advisor
    Homework Helper

    well yes, but i think he was after why the electron don't fall deeper into the potential well of the proton than 13.6 eV. :)
     
  11. Jan 10, 2009 #10
    Yes, at least Feynman think it's plausible demand. He gave his answer in his famous Lecture on Physics volume 3, page 5 of chapter 2, hope you have a copy

    I like Feynman's idea that if you can not explain something to a layman so that he can understand it, you don't understand it yourself.
     
    Last edited: Jan 10, 2009
  12. Jan 11, 2009 #11
    you do realize that the electron doesnt actually 'orbit' the nucleus. right?
     
  13. Jan 11, 2009 #12

    malawi_glenn

    User Avatar
    Science Advisor
    Homework Helper

    it is a difference in explaining things in layman terms and "non-QM" terms. Maybe you like the idea since you are not a physicsits yourself? ;-)

    Anyway, it is philosophical problem since our daily life language is developed over thousands of years to describe daily life phenomenon. It will be like a blind man demanding someone who can see to describe colors.

    And well, feynmans answer is basically telling you one way to see it. But he uses QM terms, he invokes the uncertainty principle.

    And if this is the correct way of answering the question why the electron is not bounded harder to the proton, I would doubt. The uncertainty principle is used often in layman explanations, but one does not really uses that principle at all when deriving binding energies etc. So by just be given an answer that can be understood, does not mean that the answer is correct.
     
  14. Jan 11, 2009 #13

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    Why don't you try it yourself? Try explaining, say, classical E&M for a bunch of layman and see if you can get them not only to "understand" it, but understand it in the SAME way.

    I've been involved in public outreach for the work that I do for many years. No matter how hard one tries, a person can only "understand" something based on the level of knowledge that he/she already has. And since everyone has different knowledge and experiences, this means that practically everyone understands things differently, even if given the SAME set of information! Try it if you don't believe me.

    So don't give me this tired argument that if one can't explain it to a layman, one hasn't understood it. You have no clue on what you are saying, besides the fact that you haven't defined what is meant by "understand". If you pay that much attention to Feynman and you accept his words as "gospel", then his "shut up and calculate" should have sufficed and you shouldn't be asking any anymore. How come that part didn't take?

    If this thread degenerates into philosophical issues, it will be moved to that forum where you'll get very little legitimate physics. Is this what you wish?

    Zz.
     
    Last edited: Jan 11, 2009
  15. Jan 11, 2009 #14

    Vanadium 50

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2015 Award

    ZapperZ, I agree. Often this is used in a way very close to, "I am not going to put any effort into understanding this, and if I still don't understand it, it's your fault!"

    "Feynmann", quantum mechanics was invented to explain exactly the question you are asking. Asking for a non-QM answer is like saying "explain why a sliding object eventually stops without using friction."
     
  16. Jan 11, 2009 #15

    edguy99

    User Avatar
    Gold Member

    To ask the question more specifically, consider an electon and proton relatively at rest (both with kinetic energy of less then .1 evolts) and approx. 1 angstom apart. Where is the electron after a few attoseconds?
     
  17. Jan 11, 2009 #16

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    I have no idea, because you might as well come up with other implausible scenario.

    Why is this implausible? Because how does one get two things (a proton and an electron) to be at precisely not only a particular location, but also to be AT REST as the initial conditions. By simply knowing that, you've already altered any kind of situation that you want to simulate, especially for an atom, i.e. this will probably not become an electron being captured by a proton to become a hydrogen atom.

    Zz.
     
  18. Jan 11, 2009 #17

    edguy99

    User Avatar
    Gold Member

    The problem is specified not with an AT REST electron, but a slow electron and "approximate" locations not exact locations. All I am trying to do here, is see how accurate the electron can be tracked and/or simulated and the 2 compared. Clearly there are times when people track electrons in a traditional sense. How far can that envelope be pushed both in simulations and in real life?
     
  19. Jan 11, 2009 #18

    Vanadium 50

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2015 Award

    I wouldn't say "implasuible". I would say "impossible".

    Placing an electron within a window of 0.1 A and with an energy less than 0.1 eV violates Heisenberg uncertainty. You can't ask QM how a state evolves if that state isn't possible to begin with.
     
  20. Jan 11, 2009 #19

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    This is what you originally wrote:

    We can "track" single electrons. That's what we do in cloud chambers and other particle detectors. What we can't do is place those two at the location that you want under the conditions that you want.

    If you want to solve this classically without regards to reality, then knock yourself out. That's a simple problem in classical E&M. But to do that quantum mechanically under such condition, I don't see that happening.

    Zz.
     
  21. Jan 11, 2009 #20
    the electron cant be placed at that position but what about the electron cloud?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Electron crash into Proton
Loading...