Why do we need Quantum Gravity?
One of the most famous and important open problems in physics is implementation of gravity, more precisely General Relativity (GR), into Quantum Mechanical (QM) framework. GR & QM are not compatible to each other for various reasons. The GR is based on a smooth spacetime whereas QM is discrete & probabilistic in nature. There are 2 key points in QM. Conflict of QM & RT; Spacetime Continuum & Quantum discrete 1. Physical observables are mathematical operators. 2. Hermitian operators (such as position & momentum) cannot be measured simultaneously. The products of their errors is equal or larger than h'/2. This limits our ability to measure physical the observables. (h' is a reduced Planck's constant). There is also an uncertainty relation between Energy & Time. But here is a catch. Time 't' is just a parameter; not an operator. Ordinary quantum mechanics treats time as absolute & external to the system. In Relativity Theory, space and