Actually, the no-hair theorem (i.e., John A. Wheeler's (1911--2008) "black holes have no hair" rule) has been challenged since mid-2012 by black hole firewall paradox and other problems with understanding the event horizon (see, e.g.,

It is hard to discuss these arcane problems with our concept of the event horizon.

They are tricky and yours truly is ignorant and there are **NO** generally accepted solutions.

But event horizon problems
imply black holes may **NOT** be
nearly as simple people once thought when the
no-hair theorem
ruled supreme.
In fact, now there is a
yes-hair theorem (2022)
(see also Pallab Ghosh, BBC, 2022), but
even if this is confirmed, the
no-hair theorem is probably approximately true
at least effectively.

To avoid difficult subjects, we will largely skirt the
event horizon problems, but
**NOT** forget them entirely.

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