bjschaeffer
Thinker
- Joined
- Apr 13, 2012
- Messages
- 148
Let me re-re-reexplain. I'll stick to the easy part.
There are three charges in your setup. Right? The proton charge (p+), your half-neutron (n-), and your half-neutron (n+). In doing your calculation, you took into account the electrostatic potential between p+ and n-. You call that distance r_{np}, so you plugged in binding energy -1/r_{np}.
My first calculation was by neglecting the positive charge of the neutron it gave 1.6 MeV see #525
My second calculation was with the simple dipole formula, see #525 giving a minimum at 2.3 MeV
It is not a high precision but better than nothing… It will be always possible to enhance the precision by specialists of numerical calculation.
My third calculation was without approximation but with a flat spot instead of a minimum, giving a binding energy of 2.2 MeV (to be published in a Chinese journal). This comes from Coulomb singularity but it doesn't change much the result.
You *ignored* the separation (d) between n- and n+ inside the "neutron". But that's is indeed a charge-separation, and incurs a binding energy -1/d. You thought you could ignore this term and call it an "approximation", but the term you ignored is much, much more important than the term you included.
The separation distance between n- and n+ is 2a or d if you prefer, the dipole moment distance.
(You also ignored the repulsive p+ n+ potential, at distance (d+r_{np}). At least you *knew* you were ignoring this one, and since you guessed that d was large it was reasonable to ignore it. But d isn't large, as we will see.)
There is no repulsive force between a charge and a dipole, only an attractive force because the positive charge is farther away from the proton than the negative charge (see Feyman).
Go ahead, BJschaeffer, try this: calculate the potential energy of a state with r_np = 1 fm and d=1. That's pretty close to the thing *you* think is the bound state. (Include the magnetic repulsion or not, I don't care, it doesn't help.) Tell me the total energy.
The potential is infinite, it is the Coulomb singularity. As I showed above it is not a real problem, the numerical results being not very different. A so-called cut-off or a "Taylor expansion" are not necessary. More over it is a problem because it needs adjasted parameters…
Try this: calculate the potential energy of a state with r_np = 1 and d=0.01---a case where the neutron *does not* "polarize", but stays compact . Tell me the total energy. It's lower. How is it that you "minimized the energy" but I can find a lower-energy state? Because your approximation was missing an important term, and mine is not.
The graphs shown have been obtained with Excel. I don't understand your problem.
In fact, the binding energy is arbitrarily large for d=0. What does this tell us? Well, it tells *me* the same thing that it told Niels Bohr: charge bound states are constrained by quantum mechanics, so your whole electrostatic model, which ignores quantum mechanics, is gibberish. What should it tell *you*? It should tell you that your electrostatic model was a "nice try", and now that you've worked it out better, you see that it does NOT have a deuteron-like bound state.
It is not necessary to know the value at when r=0, only the minimum of the potential. There are no "states" in my theory, only classical electromagnetism.
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