What particles are black holes made of?

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Main Question or Discussion Point

What particles that constitute the black holes?Does normal particles constitute the black holes?
How can we calculate the ratio of types of particles in the universe(we consider known matter but not consider dark energy and dark matter)?How can we calculate the total number of particles in the universe?
 

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  • #2
DaveC426913
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Black holes are not made of particles. A black hole is defined by a region of extremely curved space, caused by the presence of extremely dense mass. The type of mass that creates the curved space is irrelevant.
 
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Then if we do not consider Black Holes,Dark Matter and Dark energy,could we calculate the ratio of types of particles? Could we calculate the total number of up and down quarks,of electrons and of neutrinos in the Universe?
 
  • #4
PeterDonis
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could we calculate the ratio of types of particles? Could we calculate the total number of up and down quarks,of electrons and of neutrinos in the Universe?
We can make rough estimates for the number of atoms in the observable universe based on the total amount of mass; see, for example, here:

https://en.wikipedia.org/wiki/Observable_universe#Matter_content_.E2.80.94_number_of_atoms

This estimate is based on most of the atoms being hydrogen atoms, so the number will also give a rough estimate of the number of protons (and hence quarks) and electrons. You could use estimates of the relative abundance of heavier elements to make a rough estimate of the number of neutrons (which would adjust the estimate for quarks). I'm not sure how you would estimate the number of neutrinos, since they are too light to affect the total mass significantly.
 
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Orodruin
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I'm not sure how you would estimate the number of neutrinos, since they are too light to affect the total mass significantly.
Most neutrinos are part of the cosmic neutrino background. You can compute it the same way you compute the photon density from the CMB. The result is large, neutrinos are the second most abundant particle in the Universe.
 
  • #6
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The cosmic energy inventory does a related estimate: not particle numbers, but energy. Divided by the typical energy per particle it gives particle numbers. For atoms. about 3/4 of the mass is hydrogen and 1/4 is helium, the contribution from other elements are negligible (unless you consider planets separately).
 

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