What particles are black holes made of?

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SUMMARY

Black holes are not composed of particles; rather, they represent regions of extremely curved space caused by dense mass. The specific type of mass creating this curvature is irrelevant to the definition of a black hole. To estimate the total number of particles in the universe, one can use the mass of observable matter, primarily hydrogen, to derive rough estimates of atoms, protons, and electrons. Neutrinos, while abundant, are challenging to quantify due to their low mass and minimal impact on total mass calculations.

PREREQUISITES
  • Understanding of general relativity and the concept of spacetime curvature.
  • Familiarity with particle physics, specifically quarks, electrons, and neutrinos.
  • Knowledge of cosmology, particularly the observable universe and cosmic background radiation.
  • Basic mathematical skills for estimating particle counts based on mass.
NEXT STEPS
  • Research the principles of general relativity and its implications for black hole formation.
  • Learn about the cosmic neutrino background and its significance in particle physics.
  • Explore methods for estimating the number of atoms in the universe using mass calculations.
  • Investigate the role of dark matter and dark energy in the universe's particle composition.
USEFUL FOR

Astronomers, physicists, and students of cosmology who are interested in the nature of black holes and the composition of the universe.

fxdung
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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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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.
 
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?
 
fxdung said:
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.
 
PeterDonis said:
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.
 
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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