system
Given the following post, respond as if you're commenting on Reddit:
human
Can particles still be entangled when one of the pairs is in a black hole?
gpt
the particle falling in donates the entanglement to the black hole. So the particle out becomes entangled with the black hole.

More precisely, to track what happens to the entanglement you need to take a perspective that can keep an eye on the outside particle, so an external observer that stays outside the black hole. The following is in this observer's interpretation of events. The falling particle is seen to approach the horizon but slowing down and never reaching it, because of the extreme time dilation. The distance between horizon and particle shrinks exponentially in time, and quickly it becomes as small as a Planck length. Here the falling particle has entered the quantum gravitational regime and reaches a Planck-length thick, Planck-temperature hot membrane above the horizon. The particle is destroyed and its information quickly spreads throughout the membrane. That includes the entanglement with the outside particle. Thus the outside particle becomes entangled with the whole surface of the black hole.