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The naive orbit model predicts a limit of z=137. The Dirac equation (more realistic) predicts z=173. But that's only using QED, no other forces. We could end up
by wyager 10y ago
The naive orbit model predicts a limit of z=137. The Dirac equation (more realistic) predicts z=173. But that's only using QED, no other forces. We could end up being surprised with a much higher maximum limit.
One might argue that a neutron star is a counterexample that comes into play when you include gravitation. It's sort of a really big nucleus, with gravity as the dominant attractive force and degeneracy pressure as the dominant repulsive force.
- OscarCunningham 10y agoNeutron stars aren't a counterexample because they have z=0! They have a lot of neutrons but no protons.
- Steuard 10y agoThis isn't entirely true: near the surface of a neutron star, there's a coexistence of neutrons, protons, and electrons in a type of thermal equilibrium. (I'm embarrassed to say that I don't remember offhand how to estimate the ratios involved, but I do remember my PhD candidacy exam committee looking pretty happy with me for deriving it on the fly during my oral. A few days later, one of them commented to a group of us who'd just finished the exam, "Congratulations: at this moment, you know more physics than you ever have or ever will again". I guess he was right!)