Doctor Who?
He is from the planet Gallifrey and he is the last of his race called the "Time Lords". Time Lords were a "Master race", and fought the last of the great wars called the "Time Wars". Gallifreyen's (or the Time Lords) were fighting against an evil Master race called the "Daleks". The Doctor had to destroy Daleks and the Time Lords to end the Time Wars, which threatened to destroy the entire Universe. So the Doctor is the last of the Time Lords.
He goes around traveling to various parts of the Universe in his ship called the TARDIS (Time And Relative Dimension In Space). TARDIS is also a time machine. Time Lords as the name implies were masters of time and they had the ability and technology to travel in time. The Doctor's TARDIS looks like a police public phone booth from the 1950s London. The first thing that most people notice on entering TARDIS is that it is much bigger in the inside, since the outer form exists in a different dimension of space and time than the inner form.
The Doctor is almost 950 years old. Being a Time Lord, when his body is about to die, The Doctor is able to regenerate. The regeneration process regenerates the living tissue in the entire body, essentially replacing the previous one completely. Therefore, the Doctor looks different after each regeneration. The Doctor so far has been regenerated ten times. So as we know it, there are 10 different doctors but essentially they all share same memories and knowledge. The regenerated personality may be different to some extent than the previous one.
The Doctor and his seemingly infinite knowledge
The Doctor seems to know everything. He always has some idea what is going to happen arguably, on the least, he can sense trouble. He travels in time and space saving the universe every second of his life. For some unexplained reason the TARDIS always knows where to go (Past, present, future, and precise points in space).
So the Doctor shows up, defeats the bad guys and he is able to save the universe.
How he knows where to go is sometimes explained in the story and sometimes it is not. However, it is agreeable that "the doctor has one constant companion and that is death" (new 1st season, episode: "ROSE").
I have come up with a theory that may explain how the Doctor knows what are the most critical events in the life of Universe that will determine the path in the future and how events should be, so that the "polarity of the flow of protons" is not "reversed" in the Universe (meaning, the time lines dont run into paradox, destroying everything).
Hypothesis
Hypothesis 1:The Doctor is a re-incarnation of himself. He has led a life, and after many regenerations have finally died, only to be reincarnated as himself. So now, even though he may not remember it precisely, he always have a hint about what his actions should be.
This is almost as even though he can travel in time and space but yet has a destiny. All his actions are defined through the prism of predestination. The Doctor is among gods, but not really a god. The Doctor is much like a godly character in Franz Kafka's stories who are gods but are bound by the responsibilities of cyclic and redundant actions of looking after a system; only, the Doctor's system spans all time and space.
Hypothesis 2: Time Lords' have been around before the big bang or they have the knowledge that pre-dates the Big Bang..
This may be the only way they can go back and forth in time. The Big Bang marks a reference point to travel in time.
(to be contd. )
