# I Neutron Star Question

1. May 20, 2017

### WildBill

I am a casual follower of physics and was recently watching a YouTube video on Neutron stars. I am looking for a "simple" answer to this question.

Per the video when the star collapses with the right mass to form a neutron star, at some point gravity forces electrons into protons and flips an Up quark into a down quark and a neutrino, resulting in a change from a proton to a neutron.

The question is what is the process that flips the Up to a Down quark, is the electron directly absorbed by one of the Up Quarks, or is there a force carrier particle in the process, like photons?

That is really the main question and may lead to others, like is the electron acting like a particle or a wave when this happens and how does it single out 1 up quark to flip...

Thanks in advance to anyone that can help out on this.

Last edited: May 20, 2017
2. May 20, 2017

### Staff: Mentor

The interaction is governed by the weak force, which has 3 force carrier particles, the W+, W-, and Z bosons. Of those three, the two W-bosons are the ones that are exchanged during this process. The interaction can't really be described as the electron being "absorbed" by the proton, but I don't know of any other way to state it.

The electro-weak theory, which is a merger of the electromagnetic and weak forces, is a quantum field theory (QFT). This just means that particles and modeled as being excitations of an underlying field. So an electron is an excitation of the electron field. In QFT, there is no wave-particle duality. The electron is not a particle that turns into a wave which turns back into a particle. It is always just an electron, an excitation of the electron field.

As for how this interaction causes quarks to change, we can't say. We know that it happens, we know what the probability for it to happen is, and we can make very accurate predictions using our models. But we don't know how or why this change happens. However, we also don't know why charged particles respond to electric fields. We only know that they do and that we have rules by which we can make accurate predictions.

3. May 20, 2017

### WildBill

Thank you, that was exactly what I was looking for.