Why do we miss our past love? Why do we miss people who are no more in our life?
Channel Capacity is a term used in Cognitive Psychology to describe the space in our brain for a certain type of information. Consider your brain as a hard disk and this as a sector.
When we love someone and spend good time with them, we create memories. These memories are part of both the person is called shared memory. The interesting thing about the shared memory is that both the person remember a few common things, but they also remember complimentary things.
So only when we are together and communicating, do our brains can complete the information. Once a person is no more part of our life with whom we have a strong shared memory, when the brain tries to check the integrity of information from time to time, it can’t find the shared memory. So, for the brain it seems like part of it is missing and is no more. This is not acceptable to the brain. Brain pacifies the thought and the memory validation if the person is not alive.
So it does everything to encourage you to start looking for the person and see if he/she is alive.
If the person happens to be your past best, your brain will never allow you to forget part of it which is lost!