Why a single photon Cannot be produced from the annihilation of electron and positron?

So to create a new mass, all you need is energy. Let us take the same example you have quoted in the question. You cannot create an electron and a positron (or any pair of particles) using a single photon because the kinematics of special relativity just doesn’t allow it.

Why is it not possible that only one photon is produced by this annihilation?

If they annihilate and produce a single photon of the appropriate energy there is a problem because that photon also has a momentum where there was zero momentum before. There would need to be two photons moving in opposite directions to conserve both energy and momentum.

Do photons pop into existence?

For instance, photons—packets of light—can pop in and out of a vacuum. The speed of light in a vacuum is constant, according to Einstein’s theory of relativity, but its speed passing through any given material depends on a property of that substance known as its index of refraction.

What is quantum electrodynamics in physics?

In particle physics, quantum electrodynamics ( QED) is the relativistic quantum field theory of electrodynamics. In essence, it describes how light and matter interact and is the first theory where full agreement between quantum mechanics and special relativity is achieved.

Does a photon need the nucleus to become an electron-positron pair?

Actually, the photon does not need the nucleus to change into a electron-positron pair. According to current theories, it does that all the time. The alectron-positron pair converged again into a photon after a very short tine. I am not aware if this effect has been experimentally proven yet.

What is the field theory of quantum mechanics?

Quantum field theory. History. In particle physics, quantum electrodynamics (QED) is the relativistic quantum field theory of electrodynamics. In essence, it describes how light and matter interact and is the first theory where full agreement between quantum mechanics and special relativity is achieved.

What is quantum electromagnetic theory?

In technical terms, QED can be described as a perturbation theory of the electromagnetic quantum vacuum. Richard Feynman called it “the jewel of physics” for its extremely accurate predictions of quantities like the anomalous magnetic moment of the electron and the Lamb shift of the energy levels of hydrogen.