Newton’s law of gravity says that the strength of the gravitational attraction changes as one over the distance squared between two objects. So if you took a ball located far from Earth, it would experience a certain weight. Then, as you brought it closer to Earth, the weight would increase. Taking that equation to the extreme, as you brought the object near to the center of Earth, it would experience an infinite force. But it doesn’t.Where did it go wrong? We were considering the weight of the ball, right? In moving it over to the surface of Earth we have to take into account the actual distribution of Earth’s mass, and this means that you need to use different and more complex equations that predict different behavior.

Similarly, while Einstein’s theory of general relativity predicts that a singularity of infinite density exists at the center of black holes, this can’t be true. At very small sizes, a new theory of gravity must come into play. We have a generic name for this new theory: It’s called quantum gravity.

Scientists have proposed loop quantum gravity which can be well-defined mathematically: it expresses the fabric of space-time as a lattice of spin networks, which evolve over time. A practical example I shall give. As a diabetic I must inject certain dosage before I sit down for a meal. My hand is so used that I can almost blindly turn the pen and the reading correctly. A kind of memory from coordination of time and body works out a correct dosage as far as I know. Still I do not trust it for my muscle or my attention cannot be same at any given moment. Loop quantum gravity predicts that space-time is quantized, with a smallest possible unit or piece of space and time, beyond which space-time cannot be subdivided further. So making a maths formula does not solve the problem.

Loop quantum gravity is a difficult mathematical theory that has resisted the making of testable predictions inside black holes. However scientists now have applied loop quantum gravity to the center of black holes. They claim that the result is not a singularity.

Their calculation predicts that space-time is curved very strongly near the center of the black hole. The result is that space-time continues into a region in the future that has the structure of a white hole. A white hole is like a black hole in reverse, meaning that unlike a black hole, which pulls matter in, a white hole shoots matter out. So Alice is left with the grin of the cheshire cat. What we are yet to see the white hole spitting out the body back and it might wipe of its silly grin.

Benny