Those of you who have been reading this blog long enough to remember my post "How to Get Thinner and Age Slower" , about Enstein's Special Theory of Relativity, will already understand that travelling back through time is not supposed to be possible. The best you can do is control how quickly you travel into the future relative to someone else.
Sadly Einstein's theories have already been proved wrong by no less than the crew of the USS Enterprise, who often managed to get back to present day Earth from the future, probably when the show was running low of funds. And in any case, what did Albert know? He was, after all, only human.
As opposed to being a Time Lord. These impressive aliens can not only travel back and forth through time and space, but they can do so in something that resembles a 1960s police telephone box.
I grew up watching Doctor Who. In those days the TV license was probably only a fraction of what it was today, but they were still able to make 26 episodes a year of a science fiction programme. They did this by spending about 50p (sorry, I mean 10 shillings) a week on special effects and monster outfits. In fact, when the programme started, they used to film it "as live" with no cuts or outtakes, which probably saved them a few bob on wages and lighting bills.
By the time I remember it, Tom Baker was the Doctor, and the programme was in colour. They were, unfortunately, making it on video, but they did have a special effect called CSO (Colour Separation Overlay), which meant that you could film the actors against a blue screen and magically make it look like they were somewhere else. It would have looked totally convincing, except that people don't tend to walk around with blue Ready Brek-style glows around them. Not even Time Lords.
Most of the episodes past and present were novelised, and I eagerly read all of the stories that had been shown before I was old enough to watch (many before I was born, since the show started 7 years before that momentous event).
And then we went to live abroad, where they didn't have Doctor Who. However after a year or two someone in my class had a relative in the UK who sent him video tapes of the programme. He didn't have a video player, so he used to come and use ours.
I was 14 or 15 by then, and it seemed to be cheap and childish, and I stopped watching it. I came to the conclusion that I'd outgrown it.
Until last weekend. I was in the DVD shop looking for a copy of Friday the Thirteenth when I noticed that they were selling half-price Doctor Who DVDs. So I bought a couple which I remembered reading, but not watching.
Helena and I watched our way through "The Hand of Fear" (1976), which starred Tom Baker as the Doctor and Elisabeth Sladen as Sarah. I had expected to find it cheap and childish, which is why I haven't watched any sooner, but I thought that Helena would probably like it. However, it wasn't. Admittedly this one was filmed in a real nuclear power station, so there were fewer cheap sets than usual, but both Helena and I were glued to the screen for 90 minutes.
I sometimes wonder when I look at my life whether I'm ever going to live in the 21st century. I watch old films, old TV shows, I have my retro phone and play 80s computer games. Who says you can't travel back in time?