The T.A.R.D.I.S.
The T.A.R.D.I.S. is an incredibly complex piece of machinery. Any piece of technology that is capable of time travel it in itself nothing short of miraculous to say the least. Any society that can create such technology has to be incredibly advanced. Most societies that begin to develop technology of that magnitude will destroy themselves long before they can master the intricacies of space travel much less time travel. The Time Lords managed to do both. They were, after all, time lords. Each T.A.R.D.I.S. is unique. Most time travel devices will only allow its users to go back and forth through time. They will by nature also allow the users to move though space as well due to the fact that the universe is in constant motion. What makes a T.A.R.D.I.S. unique to time travel is its ability to keep the flow of time constant. This allows the user great latitude in how they interact with events. It could be said that when a T.A.R.D.I.S. enters a timeline, that it was always suppose to be there and therefore fulfills rather than disrupts history. The Time Lord that operates a T.A.R.D.I.S. has a telepathic link with it and instinctively "knows" how events are supposed to transpire. A T.A.R.D.I.S. can be considered "alive" and is often treated as such by its "owner". Most of these machines are grown rather than constructed. They change their inner dimensions as well as the ability to change their outer appearance. Most if not all of them were destroyed in the Time War. The Doctor has the only known one left. When he acquired his, it was already old and obsolete. Even though they are grown rather than constructed, they would still have manufactured components. Most of them would have smooth, symmetrical components that would insure a smooth operation. The Doctor's T.A.R.D.I.S. was different. When Gallifrey was still in existence, most Time Lords would have opted to scrap such an old machine but not the Doctor. The fact that a telepathic bond is developed between the two, the Doctor allowed his T.A.R.D.I.S. to link with him as well. He would replace components that would wear out with what ever was available. To say that the Doctor was eccentric was the epitome of understatement. Even though the T.A.R.D.I.S. was old and obsolete, it still harnessed the time vortex deep within itself, in its heart you could say. No one looked into the heart of the T.A.R.D.I.S. and came away unaffected. The Doctor himself would not look into the heart of the T.A.R.D.I.S. Those who did were affected in strange and unusual ways. One became the Bad Wolf but we are getting ahead of ourselves in this story. Despite the ability of the T.A.R.D.I.S. to keep time and space from being disrupted it was not perfect in that regard. Most events would work themselves out over a period of time no matter the size of the disruption because one individual usually was not capable of a disruption that would cause history itself to come unraveled. There are exceptions. The T.A.R.D.I.S. is capable of warning its operator that such an event has taken place and it is up to the operator to put things back in order. Such an event took place in 1888 when an ordinary human male named Nigel Brown was transported back in time to Egypt in 1000 BC where an extraordinary event took place that should have never happened. The T.A.R.D.I.S. did in fact attempt to inform the Doctor to such an event taking place but the Doctor was otherwise occupied.