Earth in the near future is invaded by aliens who are just "a bit" more technologically advanced than humans. The war is not a one sided extermination of humans, but humans are about to lose anyway.

An engineer succeeds in building a time machine for a one way trip to the past. From How fast could a civilization advance if given access to information from future? I understand that there would be many problems, but this is the only option nonetheless.

There is some space in the time machine for luggage (think DeLorean form Back to the future - it could be a bit bigger if need be, but not larger than a small truck) and the engineer takes a tablet with all human knowledge, a Google Glass like device that can translate all ancient languages, a small fusion reactor - but then has to decide between bringing either:

• the latest computer with as many spare parts as can fit in the time machine (but eventually the spare parts will run out and you have limited number of computers in the world)


• all the tools (and tools to make tools) to start mass producing an 1955 era vacuum tube computers for the whole world (but this progress will be much slower)

What is the best option and how far back should he travel to benefit most from the technology of the time, but still advance the human civilization the most? 1500 AD? 1000 AD? 500AD? 500 BC? 1000 BC? 1500 BC?

Take the tools, a gun, and a few cool tricks

The main problem here is that you can show up in history and claim you're from the future and know everything, at which point you will either be burnt at the stake for being a witch/heathen/rival witch/rival heathen, or told to get in line behind everyone else who very clearly knows the future and they have astrology, not some weird magic ... thing.

The best idea here seems to take a leaf out of a sci-fi, specifically Foundation's psychohistory. More specifically, when the Foundation decides to make a religion out of there superior tech. You want to go far back in time - basically to the dawn of human civilization (the more time the better). Good location include, but are not limited to: The Fertile Crescent of Mesopotamia, the Olmecs of Mesoamerica, or perhaps the ancient Chinese. You're looking for two key components. The first is they have a primitive religious mindset, and the second is that they look different from you. Wow them a bit by demonstrating your superiority, claim that you're a superior being, and take their children. (Not kidnap, just take them under your personal tutelage.) It's also a good idea to take a consort and have children that way. (Advantage here is to males whose limits is the number of females they have, and don't have to personally endure risky childbearing.)

The children are the key. If you can train them to work with your technology, then you can restart the modern human times and rebuild humanity at whatever point in time you want. It'll take a while to build the industry back up, but with modern knowledge, you can make defensible structures and deadly weapons until that point, after which you can more or less conquer the world. (You may be dead at that point, so leave a good set of instructions.) At which point, we'll have around 2k-3k years of progress on our modern one in present day. Hopefully you won't wind up up with some totalitarian empire after your absolute power corrupts your descendants absolutely, but even if you do, the human race isn't wiped out so ... win?

For best effect, head for either UK or USA any time from 1939 to 1989.

The last few decades have brought the most rapid advances in technology and the greatest focus on advancing technology, during WWII and the Cold War this was often regardless of the cost. Anything to get an edge over either the Nazis or the Russians during the appropriate periods was grabbed with both hands and tried with gusto, often no matter how daft it appeared to be.

Of course if your intent is purely to advance technology regardless of cost, then you could head for any of the opposing powers who also had much the same mindset, but the outcome would be ... different.

You could consider the argument that the efficiency of the German war machine during WWII would give humanity the an advantage over the aliens during the future encounter. Their willingness to pursue technological development without regard to inconveniences like ethics gives them a lead and that handing them the technology to overwhelmingly win the war gives the only positive outcome in the future conflict.

Your engineer needs to forego the trip and send an economist instead, specialising in development economics. The main obstacle to technological development throughout history hasn’t been lack of knowledge, it’s been lack of incentives. There were things like steam engines and electric batteries in the classical world, but they were largely seen as toys or amusements. Those on top don’t want to shake things up, because it might dislodge them from the top. What you need is to create the economic conditions that encourage the rapid development of technology, much earlier than they actually occurred in 18th century England. I think Diocletian is the chap to target — he identified deep-seated issues in the Roman economy and introduced far-reaching measures to correct them, but because he didn’t know what he was doing he made things worse in the long term.

It makes no difference.

Traveling back in time with technology does not, in and of itself, improve human civilization.

You just get a different civilization.

Let's say you give the Roman Empire basic computers. This means they can e.g. count better, maybe do some calculations better, probably all you've done is let their tax people work better. But no matter what technology you gave them (or any other faction), you don't change the politics or religious and social norms.

At any period in history all you can do is (maybe) influence who gets more powerful or richer. You can change how they do things (what tools or weapons they use), but not why they use them or for what goals. The goals remain the same - power.

Let's again consider Rome. Would Rome still fall ? Yes - the pressures that brought it down were complex, a mix on internal and external political, social, religious and economic factors. Would your engineer be able to change those ? Not enough.

You might change some things but your engineer cannot change everything. He/she can't change what Gods people believe in, or what social norms are in force in any location. They can't really control the whims of kings, queens, generals and politicians. They can't stop armies from breaking under attacks.

You can't stop one faction or race or religion hating another. The drives are too much for a technology or devices to change. What you change is the details, but it's too chaotic to control it all. Many have tried, all have ultimately failed.

How imagine your engineer (somehow) gains control of e.g. the Roman Empire and sets out to make it a force for improving civilization (something it actually was by the standards of the day). Your engineer can't do that forever and has now started history on a new path and does not know what will happen. Your engineer has no more control over who will invade, attack, stop trading, increase prices, what peoples will migrate and to where and all those other details, than any Emperor ever had. When the engineer dies history will go about it's own path. The Roman Empire of Engineer the First may last a hundred years and then collapse under more or less the same pressures our Roman Empire did. Who knows.

But there's no way to guarantee improvement only differences.

Knowledge of history and some lower tech gear and a few key ideas might allow for more advances than high technology because you can go back farther and introduce some key concepts at far earlier dates.

Population density is a limiting factor when it comes to technological progress, if you don't have enough people you can't maintain the specialised labour that supports higher technology. To that end antiseptic child-birth and city sanitation for example would allow you to create a sustained population explosion if you could introduce them to the Bronze Age. Taking the synthesis of streptomycin, or smallpox vaccine back would prevent the black death and possibly the Greek dark ages respectively both large setbacks to population density. Once you have the higher populations you need you can have your followers work on other innovations in later generations.

My advice would be to go back to 1500BC, with gold and trinkets to get taken seriously one should be rich and generous, iron smelting, gun powder, germ theory, detailed history books, mineral surveys, a plan outlining soil and wildlife conservation, and population-technology supports and linkages.

I agree with the others on the point that close to 2000 AD would be the best time period to go, give or take a couple of decades. The most important info to bring would be the blueprints for future batteries and power sources and technology relevant to their production. Because that is the greatest limiting factor of today's tech. Everything else has been miniaturized today to ridiculous levels. We also have conceptual design of highly advanced tech and weaponry, but their power requirements are equally huge and current power supplies are simply too inefficient. So the progress of current humanity is actually being held back by the lack of suitable power source.

Of additional importance would be an efficient power transmission system, since preventing leakage and waste of power during conversion is just as problematic.

Finally, make sure to bring a proper data and power converter/adapter/connecter for your storage device. You don't have to be from the future to know the disaster of not having one when you need it.