What would happen if a country on Earth suddenly gained extremely advanced technology hundreds of years ahead of USA?
Aaron Jantzen, former Metaphysicist (2003-2004)
It has already happened in several domains. Perhaps the most shocking is trains. The US’s trains are actually SLOWER today than 100 years ago, and there are far fewer routes offered. In the US, Federal regulators limit the speed of trains with respect to the signaling method used. Passenger trains are limited to 59 mph and freight trains to 49 mph on track without block signal systems. Speed is also limited by track type. The fastest track grade is “class 9,” rated at 220mph, but there isn’t even an inch of class 9 track in the US; Most mainline track, especially that owned by major railroads is Class 4 track, rated at only 60mph for freight and 80mph for passenger trains.
Compare this to Shinkansen “bullet” trains in Japan that regularly run at 200mph, TGV in France that regularly runs at 200mph and has been run at up to 357mph, and the Shanghai Maglev train, which regularly runs at up to 268mph. Given that the USA is unlikely to have such trains within the next 80 years, and the US’s trains are no faster than 120 years ago, that is already a two-century disparity in technology between the US and several other countries, and even if those other countries do NOTHING in the next 80 years to advance their technology their lead should last throughout this century; The US has no plans to catch up or surpass this technology.
译文来源：三泰虎 http://www.santaihu.com/46621.html 译者：Jessica.Wu
We already have, we've just chosen not to use it.
Yet.In all seriousness, the problem with this question is that it relies on the myth that technology gets better as time goes on. That there is some kind of ‘natural progression' to technology. This is false. Technology simply develops according to our needs, and sure, what we have today would seem like magic to people a thousand years ago, but who's to say what the state of human technology will be a hundred years from now? What if we have a nuclear war? What if technological development stagnates, as it has done before? And what is it about a smartphone that makes it ‘more advanced’ than, say, a camp fire? One is new, one is old, but one is vastly more useful for a certain purpose than the other, and vice-versa.
I'm assuming that you mean “country A has modern technology, country B has Starfleet”. In which case, the answer is obvious. Country B, or its citizens, would eventually share or sell the technology that enabled their Starfleet for great profit, and parity would be achieved in short order. Humans outlived other hominins precisely because we share our knowledge. Whether that sharing is because of greed, colonisation that brings country A up to speed by mistake, or whatever is irrelevant, it will eventually be shared.
You'll notice that despite the level of technological development, most countries on the planet have access to automobiles, for example, regardless of whether or not they can build them on their own.
This is a very interesring thought experiment. In my answer I make the assumption this technology advance includes many technologies, including military ones that eliminate the nuclear war armageddon scenario.
USA's wars of aggression stop. Its national government falls either from within or without. The new superpower becomes the new meanest baddest bully on the block once their power corrupts them.
Rupert Kavanagh, Legitimist Absolute Royalist
America would try to buy the technology/technologists; then America would declare it all to be greatly over-exaggerated and that the USA was still the Best and the fount of all invention; then America would discover hideous human rights violations in the country and bomb and invade the people there for the sake of women's’ and children’s rights and to get rid of a despotic government and the mad tyrant who kept the people in servitude.
Also something about Free Trade.
Jack Frost, former RF Microwave Consultant at R. J. Frost (1992-2000)
Trains are a step backwards and certainly not advanced technology capable of changing any countries status in the world.
If Fusion reactors became reality and were minature and easily portable it would allow the country to rule the world. Harnising unlimited energy would allow unlimited power, both political and mechanical.
If such a discovery were made in most any country except the US if would probably be suppressed and taxed out of existence. Consequently until it's discovery 100 years later in the USA it would be of no real value.