Negative energy in Dirac equation

[kahoomann]

When Dirac solved his equation for electron, he found out there are negative energy states.
My question is why electrons won't jump from positive energy state to negative energy states and release energy as photon?

Dirac proposed that all negative energy states have been filled so electrons can't jump to negative energy states. It's clearly contrived

 

[ismaili]

When Dirac solved his equation for electron, he found out there are negative energy states.
My question is why electrons won't jump from positive energy state to negative energy states and release energy as photon?

Dirac proposed that all negative energy states have been filled so electrons can't jump to negative energy states. It's clearly contrived

Yep. You can say that the Dirac sea picture is kinda artificial, but, anyway, it's a successful phenomenological model.
Actually, Dirac only solved the negative probability problem manifestly. However, the Dirac equation still has negative energy solution. This motivates the discovery of anti-particles.

Yet the complete exact solution is given by QFT where the field solutions for the equation of motion are no longer interpreted as the wavefunctions. That is, \psi^*\psi is not probability anymore. The wavefunctions become fields which are recognized as operators. And the problems disappear naturally.

BTW, I remember that I see somewhere an article saying that the Dirac sea picture is somehow can be thought of as an aether. (I'm not very clear about this.)