Place two identical 3-solar-mass black holes side by side. Add 1 solar mass of neutrons to the left-hand one and 1 solar mass of protons to the right-hand one. How will these two black holes differ?
A) The black holes will not differ at all since protons and neutrons are transformed into a common type of uncharged matter.
B) The left-hand black hole will have a stronger gravitational field than the right-hand one because a neutron is heavier than a proton.
C) The left-hand black hole will emit electrons and neutrinos as its neutrons decay into protons.
D) The left-hand black hole will be electrically neutral and the right-hand one will have an enormous electric charge.

Question

Quizplus · Accepted Answer

Once matter crosses the event horizon of a black hole, it contributes to the mass, angular momentum, and charge of the black hole. The distinction between protons and neutrons (beyond their charge) becomes irrelevant in terms of the black hole's mass or gravitational field. However, adding protons, which are positively charged, to one black hole will impart a significant electric charge to it, while adding neutrons, which are neutral, will not change the electric charge of the other.

Place Two Identical 3-Solar-Mass Black Holes Side by Side