Astrophysicists find no 'hair' on black holes

> According to Albert Einstein’s general theory of relativity, the behavior of a black hole depends on two numbers: how heavy it is, and how fast it is rotating. And that’s it. Black holes are said to have “no hair” — no features that distinguish them from their fellows with the same mass and spin.

As far as I know, there's a third property that black holes have - electric charge. Would a sufficiently strong electric charge between two black holes be detectable, whether they both have the same charge, or opposing charges?

I suppose based on the article, the effects would only take places once the black holes got within 40km of each other...

This reminds me of something I mull over; Greek style philosophy seems so smart, rational and correct until you actually observe the world. Imo the perfect example is elementary particles - the Greeks (mostly) were convinced that it's impossible for something physical to be elementary (cannot be further split) and logically it is hard to understand why can't we continue to split the particle?! but hey, we can't.

Physical beings which cannot be distinguished from one another would have made their heads spin...

    The question of hairy black holes is intimately connected to the greatest puzzle in modern physics: How can general relativity be merged with quantum theory?
    
    Consider the situation where an object crosses a black hole’s point of no return, called the event horizon. According to general relativity, all outsiders will see is how the swallowed object contributes to the two numbers that describe the black hole: how much mass the object adds, and how much faster or slower it makes the black hole rotate.

The idea that anything within the event horizon should be treated as an opaque black box -- could it be reinterpreted as saying that any property which has dependence on spatial or temporal distribution within becomes an unknowable quantity? If so, can it be tied somehow to Quantum Mechanic’s idea of the removal of degrees of freedom by observation, since now certain quantities are not unobserved but rather unobservable in principle? I am asking this from a naive laymen’s point of view, so I may be conflating entirely unrelated ideas.

Black hole goes into a barbershop

Barber goes "You're kidding me, right?"

An interesting consequence of having "no hair" on them is that information on everything that falls in them is lost forever, which leads us to an information loss paradox. Not nice.

Another blow against string theory.

Yet another clickbait title by the quantamagazine. I'm afraid these "science popularization" techniques only make it more confusing for the general public. Just say the exact, scientific word and cut this bs.