What is meant about (hair)?
The only info, according to the no-hair theorem, that we can get from a Black Hole is only about its mass, electric charge and angular momentum because all other info (which was called hair) gets lost behind the event horizon.
Steven Hawking stated that black holes do have hair and he proposed that at least some of the information devoured by a black hole is stored in "hair".
The 'hair' of a black hole relates to the notion that a black hole has only three properties - mass, charge and angular momentum. This is commonly referred to as the no hair theorem formulated by John Wheeler [who blamed it on Jacob Bekenstein]. In quantum physics, this violates the principle that quantum information must cannot be destroyed. However, information, as defined under quantum physics cannot be encoded using only these three parameters, thus leading to the black hole information paradox. The only apparent solution to this paradox is either that quantum information can be encoded using only mass, charge and spin, or, that black holes have other definable properties. Physicists have argued the 'information paradox' for decades, but, an entirely satisfactory resolution has proven elusive. An attempt offered by this paper: http://arxiv.org/abs/1601.00921, Soft Hair on Black Holes. has been a hot topic in the physics community lately.
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