We are guided in our understanding of the interior of black holes by the theory of general relativity developed by Albert Einstein, and in particular, the mathematics of the complete, relativistic equation for gravity and space-time. This theory describes in considerable mathematical detail, both those regions of space-time that are accessible to humans, and those that are accessible only by individual observers but not distant observers. For black holes, distant observers will see only the outside of the event horizon, while individual observers falling into the black hole will experience quite another 'reality'. General relativity predicts that for distant observers outside the horizon, they will experience the 3 space-like coordinates and 1 time-like coordinate as they always have.

For someone falling into a black hole and crossing the horizon, this crossing is mathematically predicted to involve the transformation of your single time-like coordinate into a space-like coordinate, and your three space-like coordinates into 3 time-like coordinates. Along any of these 3 former space-like coordinates, they now all terminate on the singularity, and your experiencing them as time-like now means that you have no control over your destiny because all choices always terminate on the singularity...at least in the case of a non-rotating black hole. The coordinate which used to measure external time, now has a space-like character which affords you some wiggle room, but dynamically, in terms of these new reversed space and time coordinates, you find that no stable orbits about the singularity are possible no matter what you try to do. Without any stable orbits, and the inexorable free fall into the singularity, relativists often refer to this as the collapse of space-time geometry.

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