I was wondering about what happens when a black hole forms.

I mean, a black hole forms when a star collapses, so when an enormous mass of protons, electrons, neutrons etc collapses together.
But when it does, all those particles should come "in contact", so what happens when electrons and protons come in contact?
Shouldn't they annihilate each other releasing energy?
In the end, shouldn't the singularity be composed only by the mass of particles without an electrical charge?

I'm not a professional, I just find astronomy fascinating and I like to read about it, so forgive me if I said something obviously wrong :)


1 Answer 1


Electrons and protons do not annihilate each other, since protons have a much greater mass than electrons. Only matter and antimatter does, since a particle and its antimatter counterpart have the exact same mass.

However, under the right conditions, an electron and proton can combine. This forms a neutron, since the charges will cancel each other out. This process is called electron capture, and it's the reason why neutron stars form.

I'm not an expert on black holes (I haven't studied GR), but I know that a lot of black holes form from neutron star collapses.

  • $\begingroup$ Thank you very much! thanks to you i've also understood how a neutron star forms! :) $\endgroup$
    – giocarmine
    Commented Jun 23, 2016 at 8:35
  • 1
    $\begingroup$ @giocarmine Yep, but just so you know, protons and electrons will not always combine. They only do so under high enough energies. So neutron stars form when the mass (and energy) of a white dwarf goes beyond a certain point. $\endgroup$ Commented Jun 23, 2016 at 16:12

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