My question was raised by this post.

Aliens crash-land at the Boston Airport (ie, in the United States). [...] The potential benefits of being able to reverse-engineer their tech alone is enough to propel the US to a new level of technology.

This happened in the early 21st century. After some years, the US have extracted enough knowledge from the spaceship and its passengers to create a huge technological gap between them and the rest of the world. Assume (if that makes any sense) that this gap is similar to the difference between WW2 and 2000's techs.

I guess that all this knowledge will leak at some point (intelligence services, private companies, bribes, retro-engineering of latest American devices...). So the question is,

How long before all other (developed) countries get to the same level of technology?

If you have to address the resulting political transformations too much, then this question may be too broad...

We can also assume that a part of this technology will be classified and only available to the army, and that the US will use their advanced weapons in conflicts. But since other countries still have "regular" nukes, the US cannot get into a world war with impunity neither.

If by "the US", you mean the general population, you're out of luck

It's (probably) feasible to keep certain findings secret if you stash them in a safe, bury that in concrete and tell no one about it. The hard part is making use of your knowledge without giving it away. In an age of more-or-less free travel and wireless, anonymous data transfer, anything you sell, mass produce or make accessible to regular citizens will spread almost instantly, no matter how jealously you guard it. If you were able to reverse engineer the alien tech in the first place, others will be able to figure out your adaptation of it with far less effort.

Science is a global effort

A big part of technological progress is knowing what's possible, and in which direction you should focus your efforts. Going back in time 50 years with just a list of "lessons learned", no details, would be huge. This, again, is not something you can keep secret from the rest of the world very easily. If they know you have it, half of your advantage is already gone.

Of course, the devil's in the details, and someone has to do the actual work of figuring them out. Contrary to popular fiction, this is usually not done by a lone genius in a basement somewhere, it's the result of a lot of moderately smart people making incremental progesss and "comparing notes". Militaries are sometimes able to build on top of that (or rather, private companies do and then sell the results to one or more militaries), but they're never too far ahead of the curve.

What this means for reverse engineering your alien tech is that the speed at which you'll unlock it is inversely proportional to your secrecy. Every researcher you give access to this project is a potential leak, as is whoever supplies their resources. And once there is a leak, your small research team has to compete with the rest of the world.

Testing weapons is probably fine, waging war is risky

The US are already known for building and test firing lots of prototype weapons that, while the underlying tech is common knowledge, haven't been implemented at that scale anywhere else. Assuming they'd gain enough of a technological edge to make these weapons actually superior to established alternatives, there would be a number ways to profit:

• Intimidation: The US and NATO are already a major military power, so, bragging rights aside, the new weapons wouldn't really allow them do do anything they could not do before. That being said, misinformation about what your new tech can actually do might give you an edge in negotiations.


• Intelligence: If you keep it secret, you can use the advanced tech to spy on your enemies and wage a (dis)information war. They'll eventually figure out that you have some kind of unfair advantage, but without access to your facilities, there's not much they can do to properly analyze or replicate it unless they beat you at your own game.


• War: Large scale production of even a conventional new weapon is ridiculously expensive. Even more so for your alien tech. The effort of modernizing your entire military in a limited timeframe will only pay off if you fight, and win, a big war. Assets will get lost, and the rest of the world will be highly motivated to steal or reverse engineer your tech, so you quickly trade that technological advantage for a more dominant position on the globe. If you can somehow prevent other superpowers from retaliating with nukes etc.

In conclusion, the more use you get out of the tech, the faster it'll spread. If your goal is to maintain technological superiority, your best bet is to use it sparingly, e.g. for syping on other powers.

I think the best way to look at this is by seeing how long it took China to catch up to the USA's technology. 20-30 years ago, the average level of technology in China was 50-100 years outdated by Western Standards, now they have pretty comparable technologies in most areas of life; so, if you are beginning your narrative from any time period before 2000, that would be a reasonable time frame.

That said, we live in an age of hacking and surveillance where national secretes are much harder to keep than they once were. It only takes one researcher opening a bad email for someone else to gain access to an entire office building worth of research. I would not be surprised if half a dozen countries had at least some of what the USA discovered from the wreck, before they are even ready to go into production with it.

Skipping a bunch of me complaining about the complexities behind this, the answer is something in the frame of "they can keep their edge almost indefinitely if it gives them enough of an economic advantage". Short version if it costs too much to retool for the new technology it won't be adopted if the US is far enough ahead that other nations can't afford it. Look at the gap that developed between the US and USSR after the space race. It wasn't until relatively recently that Russia was able to catch up in the computer sciences through access to cheap components produced by outsourced offshore vendors in sympathetic countries.

This does assume an initial manufacturing monopoly, if they outsource production they'll lose almost immediately.

I don't think there will be any appreciable delay at all.
There are to many variables at play to answer precisely (and I assume the question will be marked as opinion based soon). But my overall line of reasoning goes like this - in this scenario the US doesn't have much head start over other nations, they do not have the infrastructure in place to produce alien technology devices at once. In short, the more secrecy there is around the alien technology, the slower the rate of adoption in the US itself, so the nation gets less benefit from it's new technology. The less secrecy, the faster it spreads.
The best use of this technological superiority, IMO, would be not trying to conceal it, but to patent it - but then you will have it produced in China and used globally the next morning (although US would profit economically the most, I guess).

UPD: the main point I see here is that initially US itself is in the position of a developing nation - they have reverse engineered alien blueprints and no manufacturing base to produce them. To use this technology, US would need to invest into overhauling its manufacturing base first. So, using this alien technology will get expensive before it gets profitable. And in order for it to get profitable you need to actually sell it, and other countries to buy it. So in this 'peaceful' scenario the whole world gets technology, though US profits.

If the technologies are going to be used only for military, US is going to have problems with its NATO allies unless it shares. I do not think there are many pieces of technology your would want to go to war with the whole world. And barring some comic-book superweapon, most military technologies take decades to integrate and implement.

The only way some alien technology can assure swift and decisive technological and military dominance is the case where it is its own manufacturing base - something like self-replicating nano-robots. And that is not 50 years worth of technological difference, it's magical philosophers stone for all intents and purposes.