We all know that when the Doctor is injured he regenerates. Originally this came from a necessity of having to replace William Hartnell. They could simply have replaced the actor. I remember they did this in Lois & Clark: The New Adventures of Superman with the character of Jimmy Olsen. However in Doctor Who they chose to make it a part of the plot which is wonderful. (Obviously not a option for Superman)
I think that regeneration was handled better in the old show. I don’t like the knew graphics used for regeneration. The explosive orange looks silly. Obviously explosive orange was impossible for the original series. In the time The Tenth Planet was made there was nether orange nor computer graphics.
The fading from Hartnell to Troughton looked more natural than the modern series. This is supposed to be a biological function after all. That’s just my two sense.
I wonder though might regeneration be possible for us? Immortality is discussed in many science fictions and some say it might be a real possibility one day. If you know anything about biology, which I don’t really, you’ll know that human cells replace themselves every seven years. In essence there isn’t a cell in your body that was there seven years ago. As we age this replacement process becomes less and less efficient. So what if there were a technology that could assist the body in cell replacement but not lead to weakening and death.
I rather like the idea of immortality – I’m assuming that your immortal body was one that was still a nice place to live. If you could find a job you enjoyed then you could see the world. Boredom would be impossible. There would still be millions of books to read, TV series to watch and places to visit. And if you left it a few decades between visiting each place, watching a TV series, or reading a book it you would have forgotten about it and, in the case of a place, it would have changed a lot.