I have trouble understanding the concept of imaginary time. As I understand it (by reading other online sources), imaginary time was developed by Stephen Hawking and Hartle in their theory of quantum cosmology. Quantum cosmology is applying quantum mechanical principles to cosmology as a whole, so the concept of the wave function is applied to the universe as a whole. There are infinite number of parallel universes as a consequence of applying the wave function to the universe. Also, an application of imaginary time can be found in quantum tunneling. When a particle is in the process of quantum tunneling, it is said to be in imaginary time. There are other technical terms I encountered during my reading such as Wick's rotation and Sum Over History Path Integral which I wasn't able to understand. Is my understanding of this topic accurate at all? Is there more to the story than this?