Let start with a current history tech-levels. Suppose, a relevant scientist in a mid-tier Great Power in 1850s receives a mysterious package.

To be concrete, let's say a mid-tier Great Power is maybe not UK (it's too much), but France, Germany, Russia, USA; maybe throw in Japan for the giggles.

A tube-based radio

The package contains schematics and build requirements of a vacuum tube, complete with the schematics of some radio sender, receiver, build plans for smaller parts like resistors as capacitors, and some (but not much) of the theory behind it. Basically, it's all needed (for a sufficiently advanced tech) to reproduce vaccum-based radios. Let's throw in two pre-assembled demo kits for completeness.

Let us assume, the scientist has enough oompf to kick the doors of some generals and to convince them to fund the required research (Manhattan project style, if needed). Let's focus on WW2-era of tube tech, to be concrete.

Would a particular country (up to your choice) be able to reproduce the radios and use them? (In a warfare, of course, that's what Great Powers do.) Bonus: further social and economical consequences.

Consequences such as light-bulbs, hence better destroyer detection at night, but also better street lights in the capital of the mighty Great Power.

On the one hand side, I see trouble with the materials, the required degree of purity / build quality, esp. the vacuum. On the other hand, it does not seem really hard, with enough explanation / theory behind it, this tech would work with worse materials. The quality / longevity / price might suffer, but a Great Power does not care, as it as it still works somehow. Because, come on, "whatever happens, we have got, the radios, and they have not".

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    $\begingroup$ Plain old analog vacuum tube radios could have been produced in any European country at any time after 1600 or so. There is nothing in them that could not have been made by any of the armies fighting the Thirty Years War. OK, their thermionic cathodes would have been less efficient, etc., but they had all the essential technological base. Yes, they did not know how to make good enough vacuum pumps, but those are not really such a complicated thing either, nothing which they would have found difficult to understand. Basically, if it can be made in a garage, it could have been made in the 1600s. $\endgroup$
    – AlexP
    Commented Sep 4, 2023 at 17:42
  • $\begingroup$ P.S. About that "theory behind it". James C. Maxwell's Dynamical Theory of the Electromagnetic Field was published in 1865. That is the "theory behind it". Ah, and in real history the first decisive battle where radio played a crucial part was the Battle of Tsushima in 1905. The Japanese fleet had functional radio. The Russian fleet did not. $\endgroup$
    – AlexP
    Commented Sep 4, 2023 at 17:49
  • $\begingroup$ @AlexP: Ok, "garage argument" hits it hard. Thank you. As for the radios in Tsushima, I think that both sides had radios, but the Russian were in a worse shape due to the long travel. $\endgroup$ Commented Sep 4, 2023 at 17:59
  • $\begingroup$ Yes, I know they both had the hardware. That is why I said functional radio. $\endgroup$
    – AlexP
    Commented Sep 4, 2023 at 18:00
  • $\begingroup$ Are tubes a requirement? Simpler radios might be less efficient, but much easier to build. $\endgroup$
    – EdvinW
    Commented Sep 4, 2023 at 21:09

2 Answers 2


"Radio but earlier", you say. I will focus on that.

So, may I suggest that you simply skip the vacuum tube option... just go straight to semiconductor transistors: functionally equivalent to the tube and much simpler to build.

the only reason we had vacuum tubes before semiconductors is that we had to understand a little about quantum mechanics to conceive the application of semiconductors to this purpose. But you seem to be suggesting (apologies if I'm mistaken!)that the "mysterious" package contains knowledge from the future. So I'm responding by suggesting that instead of "knowledge of vacuum tubes", supply "knowledge of semiconductors."

Either way, vacuum tubes or semiconductors, the person who receives the package has no idea why these technologies work... and since it's easier for them to build the semi-conductor device... give them that knowledge instead.

Just for clarity, the semi-conductor transistor supplies the same functionality as the vacuum tube: the ability to amplify the received (very weak) radio signal.

For that matter, your mysterious package could contain instructions for BOTH kinds of technology: vacuum tubes AND semiconductors. Maybe you will want there to be two teams who race each other to build the first fully functioning radio transmitter & receiver. (obviously, the "problem" with the semiconductors is sourcing the "doping" material for the semiconductor... maybe they have

For completeness, you might like to provide the deeds for constructing a rudimentary semiconductor transistor. Maybe ask that question here if that's interesting to you. Oh. Check this awesome YouTube video on the topic: https://www.youtube.com/watch?v=vmotkjMSKnI ... here you see the key moment where she is salvaging the semiconductor material from a diode! https://youtu.be/vmotkjMSKnI?si=4FLu4VTlCsQHCjOp&t=229

Obviously, this is not how the mysterious package will explain it. The only significant challenge is to manufacture the "doped" semiconductor. But maybe the mysterious package can simply supply enough of that to make a bunch of transistors. Not sure how to creat that doped semiconductor. Maybe it's easier than I realize for a "sufficiently advanced" civilization provided they simply have the instructions.


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    $\begingroup$ While semi-conductors are simpler in theory they also require extremely pure germanium or silicon to work which was well beyond the capacity of the 19th century to produce. $\endgroup$
    – OT-64 SKOT
    Commented Mar 7 at 6:44

The answer depends on the details of the package, who got it and how well respected they were. Worst case who ever gets it is ignored as a crack pot as no one can be bothered to give them the time of day.

Best case the person who gets it is very well placed and has all the right connections they get noticed and the military / government jump on the project and encourage further development. In which case the military get the radio.

Another key aspect is when does this package arrive in terms of wars? If it happens just a few years before a war they will have the advantage, if its a lot longer the secret will probably leak out and everyone will want or have one.


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