h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I have another explanation for the lack of anachronisms. Perhaps, although thime travel is easy, the universe requiers time to be self consistant. If someone goes back in time and introduces modern technology in the past, that means that they had already done it, and the technology will seem to have been invented at that time. How do we know that edison didn't get his ideas from a time traveler from today?

Because Edison's inventions were consistent with and amenable to analyis by the technology and theories of the time.

If I took a solar powered laptop computer back with me a scant hundred years to Edison's time, he would not only not know how it worked, he'd not have any way of working out how it worked. He would lack the instruments to examine it in the detail required to reverse engineer it to a point where he could duplicate it, and even if he had the instrumentation he (and everyone else in the world) would lack the theoretical framework which underpins its construction (operation of semiconductors, for instance, or the photoelectric effect).

It's funny - you could probably take any piece of technology from, say, 1500AD back a thousand years, and be able to find someone somewhere who would understand everything about it and be able to build a copy.

But take a fairly common piece of tech from today back only a hundred years, and the best and brightest minds available wouldn't have any chance of telling you how it worked or even in some cases what it does.

As the pace of technological change quickens, the anachronism gap is going to get narrower. I remember hearing on a TV science show how the human genome would not be sequenced in my lifetime because of the enormous cost and complications. Less than fifteen years later, the sequencing was completed, using techniques of analysis and computation not even dreamed of at the time of the show.

Makes you wonder if there aren't anachronistic devices all around us, and we don't recognise them... after all, if I dropped a mobile phone in Edison's workshop, he'd have no idea what it was for, and he'd probably just throw it away...

H.

Good point, but, then, maybe if a device was too far out of the technology of a time, society would reject it anyway. Increased medchanization in the past has often been rejected, either by workers who fear they will be displaced, or by the people who run society. Or else, they wouldn't work without nonexistant infrastucture. Even if you gave a lightbulb factory to someone 500 years ago, it would be useless to them because, without electric power plants, noone could use them. One piece of technology on its own couldn't be taken back in time because technology reflects the society it developes in. Many people today couldn't do their jobs wityhout computers, but if you gave one to someone a few hundred years ago, along with the infrastructure and training to run it, thy would probably see it as worthless.

yes,but if you them what a computer can do, they could find it useful. then what? would we become more advanced then we are now?or would nothing really happen?think about it..

If some kind of totally astonishing tool was found from the future, I imagine the nearest government would take it as soon as possible. And then do secret stuff that no one gets to know about.

On the tank thing: Terry Pratchett's "Small Gods" has a sub-theme where it is demonstrated that a civilization advanced to the same level as Ancient Greece could have built a kind of functioning tank, out of the technology that was already available. The problem would be maintaining it and ensuring enough people had the necessary skills to keep it running and trouble-shoot any little malfunctions... otherwise what you end up with is an inert hulk, surrounded by technologicially illiterate soldiers hitting it with spear butts to make it "go"...

There's also a sci-fi novel by Harry Harrison where a Ku Klux Klan racist gets hold of a time machine. In a bid to manipulate the Civil war so that the right side wins, he takes back the blueprints of a Sten Gun with him. Now this was a cheap and deadly sub-machine gun that was designed so that it could be built in a blacksmith's forge or garage from whatever bits of scrap metal were available: designed to be as low-tech as it could possibly be. Our KKK racist reasons that this is the ideal weapon for the 1861 Confederacy to build in large numbers from its gunsmithing and metalworking technology, so as to really hit the damnyankees where it hurts. Enter the Time Police to confound deadly scheme...

Perhaps in both scemes, you need to have more than just a nucleus of people who really understand the technology? Otherwise inertia and entropy set in and you just have quaint anachronism that nobody knows how to operate. ("What's a "magazine", for goddamn? And this "recoil bolt assembly", how does that work?")

I imagine you could have usable weapons that only a few people understood. The giant mirrors Archimedes supposedly used to sink attacking boats would be one example.

But a mass-produced weapon manufactured by the thousand would need some sort of mass training programme to go with it. I can buy the idea that the Confederacy was technologically advanced enough to build Sten guns. Could the training have been delivered, though, to illiterate Tenessee hillbillies who were barely used to muzzle-loading rifles? Could the human raw material have learnt to work with technology from eighty years in the future? (Nothing against Tenessee, btw, it was the first Confederate state that came to mind)Would a degree of future-shock have set in?

And even if they had managed it, sooner or later captured guns would have travelled North, to the Union states with a vastly better manufacturing base, so both sides would have been back to square one very soon... all the Confederacy might have hoped for would be a quick forward lunge out of Richmond to capture Washington while they had initial advantage?

Oh dear!
If you take a walk and inadvertently step on an ant, does this affect the whole of ant civilisation. If we are at the moment surrounded by interested scientists from the future, they would have been vetted, just like astronauts. They would be careful not to kill somebody, fall in love or divulge secrets from the future. Some may be tempted, perhaps to assasinate Hitler in 1933 or prevent the crucifiction. Anyone allowed to timetravel would be fully aware of the disasterous consequences or making huge changes to history. How about little changes? The only person who would really be interested in changing things in the past would be yourself. A distant procestor would not want to change your life because it would possible affect them. If you chose to change a major part of your own life then you may well ensure that you ceased to exist soon after due to a circumstance unforseen and therefore would not be able to go back and change it anyway. Thus to the little things in our present life. The feeling of having been somewhere before may be from a time you will be there in the future and have travelled backwards to check it out first. How this would influence your present mind is a different matter. The feelings of having existed before. Well a distant procestor may have taken you back in time to visit an ancestor, for research purposes and then returning to your present most of it is forgotten or written up whilst awaiting treatment!
Nothing can be dismissed out of hand as impossible. How it is achieved may well confuse our imagination but we can and do speculate. I am old enough to remember that the idea of picking up a small gadget and talking to relatives in Australia would seem....well impossible. Whilst the boffins were busy laying wires all over the world, someone thought of satellites. Just do a little people watching. Can they really all come from this time?
NB Procestor oppopsite to ancestor...but you knew that anyway.

Time travel to the past is logically and physically possible.
But it is not easy and you can't change the past.