Cut-price time travelling

Dear Dave,

One of the arguments presented against the possibility of time travel is that, if it worked, we'd know about it - we'd have been visited by bus-loads of very smug people from the future by now.

Personally, I think there are a number of reasons why any successful time traveller would try to remain inconspicuous. More than that, they're bound to be very rare, since there's every chance they'd fail to pass on technical details of their discovery. For a start, travelling in time is extremely dangerous. It's well known that time travel almost always ends in being eaten by a dinosaur, enslaved by intelligent chimpanzees or exterminated by a Dalek. None of these outcomes is really conducive to getting scientific papers widely published.

Then there's the issue of paradoxes:

Thanks to Back to the Future, everyone is aware of the unfortunate consequences of chatting up their own mum. These simply aren't worth the happy side-effect of creating rock'n'roll. While this particular situation is easy to anticipate, other kinks in the chain of cause and effect are harder to avoid. For example, anyone who devotes their life to saving a loved one killed in a tragic pogo stick accident is asking for trouble.

What if, after years of expensive and exhausting work, they manage to make that leap back in time and warn their childhood sweetheart not crank up the spring and go for a bounce through the firing range next to the old, abandoned mine by the cliffs? If they avert the disaster, their past self has no reason to toil away inventing a time machine in order to travel back and avert the disaster. Worst case scenario, the entire fabric of the universe unravels like a toddler's knitted sweater snagged at the top of a helter-skelter. At the very least, someone's going to disappear up their own worm-hole.

Again, publications will to be few and far between.

Even if a time traveller were to avoid immediate mishap, there are only two likely uses for a time machine:

1. Travelling back in time and betting on the horses.
2. Travelling forwards in time and stealing some cool technology.

Both of these activities require secrecy. Too many people muscle in on the gambling scam and odds and outcomes change, inflation rockets and shadowy Italian crimelords begin to get upset. Too many people start leaping about stealing technology and someone's going to get the smart idea to cut down on the competition by travelling backwards, nicking the time machine plans and giving them to their earlier selves. In both cases, the risk of a paradox or a beating rises sharply with the number of travellers.

Yep, anyone who invents a time machine is going to keep it to themselves.

This is annoying because there are all sorts of advantages to living in the past. You don't have to go back that far at all before the music's better, for instance. Go back a little further and you won't have to worry about the environment because you'll be too busy worrying about nuclear Armageddon. Go back far enough and you can impress people with nothing more than a box of matches.

No matter how far you go, however, it's just plain cheaper:

A month after its release, I saw a computer game second-hand for half the original price. I resisted the urge to buy it and waited another couple of months. By then it was that price new and the second-hand price had halved again. Sure, when I took it home, I was playing a game that had been out for three months, but by living only a quarter of a year in the past, I'd made a saving of seventy-five percent.

It's the same with DVDs. One month a film is fifteen quid, the next it's in a 5 for 30 offer. By linking my home cinema via a time-warp directly to 1996, I save a fortune.

Interestingly, though, it's not the case that the further back in time one lives, the greater the saving made. With computer games, there's a point when older games start being harder to find. Really old games can become more expensive again as supply diminishes. With DVDs, the cheap version may be withdrawn in favour of the premium priced Special Edition.

What's the sweet spot? How far in the past is it necessary to live in order to enjoy the best deals?

For computer games, I'd say it's about three years. For DVDs, it's maybe only two. For music, perhaps it's five years but this is going to increase as digital downloads take over. There aren't going to be many CDs of recent music available to buy in the carboot sales of the future. Choice will be limited to the old, decent stuff bought by people like us. (Shame.)

Clothes require a little foresight. It's more complicated than simply popping down to the charity shop and seeing what fits. Very old clothes are cheap but they're likely to be falling apart and have a totally unshiftable smell of grannies about them. Relatively new clothes will be expensive and look remarkably dated. The trick is to buy clothes from ten years ago but then stick them out of harm's way in a cupboard for another five until they come back into fashion again. It's maybe time to pick up some outfits in lime green and bright orange that are going for a song...

As for fresh food, it's a case of living in last week and buying all the items that are marked down because they're rapidly approaching their use-by dates. Of course, the crunchy food will be soft and the soft food will be crunchy, so make sure to purchase a selection and choose recipes which require a variety of ingredients. It will all even out in the end.

Bear these tips in mind and your ears, eyes, mouth and wardrobe will be living in different temporal eras, but you'll save a pile of cash.

Don't tell anyone, though. We can't all do it. Someone's got to be seduced by the hype and pay over the odds for stuff on day of release in order for us to buy it second-hand later. And think of our pensions - if no one feeds the corporate machine, the stock markets will collapse and we're all doomed.

Remember: Time travel - keep it secret.

Yours in a woman's world,

Ed.

PS We'd all have a Star Trek style holo-deck in our living-rooms if they weren't just as beguiling as time machines. A guy in Pasadena invented the technology years ago. He was going to go next door and tell his neighbour but then he popped into the thing to give it a quick test-drive. That was 1993. It was simply too much fun to come out again. (Of course, he thinks he came out in 2001...)