Suppose someone went back in time to kill Hitler and fails and some modern tech falls into nazi hands. What modern technology could they realistically reverse engineer with 1940's tech?

I'm leaving the time travel tech itself out of this and am most interested in what modern tech they would be able to make sense of. For the sake of argument, the time travel device is only one way and remains in the future.

Our failed assassin might be carrying standard items that an assassin in 2021 might carry on them (phone, gun, nvg). Also, let's assume that there are no easy shortcuts and they haven't done anything like downloading the entirety of Wikipedia or arxiv onto their phone for the trip.

  • $\begingroup$ what kind of gun, what kind of night vision goggles, a phone will be mostly useless as it does not tell you much about its manufacturing technique, especially one the battery dies or they fry it trying to charge it. also the Nazi would not have much time to work on or implement said tech. $\endgroup$
    – John
    Commented Dec 17, 2021 at 0:11
  • $\begingroup$ certain gun could lead to improvement others would not, night vision googles would depend on the goggle, photocathode could see drastic improvement or nothing at depending on the night vision goggle used. $\endgroup$
    – John
    Commented Dec 17, 2021 at 0:33
  • $\begingroup$ the failed assassin was too busy revising for his modern physics exam while waiting for target to show up ;D $\endgroup$
    – user6760
    Commented Dec 17, 2021 at 2:50
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    $\begingroup$ I would venture to say that a time traveller would probably attempt to assassinate a seemingly evil person a bit closer to his time. If someone were to want to assassinate Hitler, he should actually go back further to medieval England and Spain who did worse per capita to the Jews and other minorities. Lastly, if he were assassinated and even the nzi party disbanded, another would take his place somewhere in the world, perhaps the us (which would be worse--remember that they had antisemitic and authoritarian parties in the us too, especially at the time). Hatred cannot be assassinated. $\endgroup$
    – 리주민
    Commented Dec 17, 2021 at 13:07
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    $\begingroup$ Sounds like the assassin is pro-Nazi but anti-Hitler if they waited till the 40s instead of much earlier. Killing Hitler in the 40s could arguably have helped the Nazis. $\endgroup$
    – Allan
    Commented Dec 17, 2021 at 13:59

6 Answers 6



Nothing to add to @AlexP answer, except that, for a comparison, the Manhattan Project's main difficulties were in getting pure enough materials and precise enough tolerances. In other words, even knowing exactly what something is and how it works (and here we have neither, not "exactly" enough), you still have the problem of engineering it.

In other words, you could have sent the prints for an A-bomb, the theory, the bill of materials, detailed instructions on how to produce and assemble each part, back in time to the USA (or Germany) in 1939 - and they probably wouldn't have been able to shave more than a couple of months from Project Manhattan's time table.

To be helpful, what you need is information on how to cleverly use something they already were able to use. But the fact is, people are and were quite clever - they were already doing next to the best they could with what they had.

So, no way a failed assassination and its loot might help Nazi Germany.

...and it gets worse.

On the other hand, even a failed assassination might spell utter disaster for Nazi Germany, because of its implications.

(Had they been sane, the reasoning below might have helped Germany and the Nazi indirectly, by telling them to quit while they were ahead. To sue for peace, and consolidate their earnings, and be able to strike again, perhaps more decisively, at a later date instead of hurtling towards a destroyed Germany. But I think this not to have been the case).

"So, Herr Doktor. Do you have any results yet for our Fuehrer?"

Werner Heisenberg shrugged. "The technical report is under way. I have no great hopes, as you can imagine. But..." he paused, considering his next words. There were things that no sane man was going to tell to a Party commissioner, ever. And yet...

"You have seen the man's devices. His weapon. That strange gadget he had in a pocket. You know, of course, the conclusions we've arrived at."

"You mean the time-traveler theory. Yes, of course. I understand this is established truth. Which is exactly the reason why we want to know everything possible about the man's devices and technology. His communicator alone could win us the war." said the Commissioner impatiently. "So?"

"Do you realize the effort - the technological effort that must have been necessary for this man to come back here? The energy required? Do you not realize what this has to mean?"

"Explain yourself, Doktor."

"Someone, years in the future - our estimates range from a minimum of one hundred years to a millennium - some large, very powerful entity, like a government, possibly a planetary government, sent back an assassin to kill our Fuehrer. Why would they have done this? Think! What kind of government, what kind of people would want this done?"

"I... don't think I quite see."

The physicist raised his voice. "Don't you see? Time travel must be exceedingly difficult, or we would be up to our ears in time travelers. The man was soft, well fed. He was no warrior. He came from a peaceful world... his can not have been a desperate attempt but rather a deliberate, well-researched endeavour. There is only one explanation for this mission to have been allowed -- to have been conceived. Why this mission specifically, and not another."

He took a deep breath.

"I could tell you nothing, but the facts are all out, for everyone to see. The story is too big, and it's already too late to silence. The conclusion is logical and inescapable. Somewhere, in the next few years... the Third Reich must have lost. So horribly, so finally, that future generations will not be content with letting things stand, but endeavour to wipe us all out from the very history."

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    $\begingroup$ Imagine their horror if the man was a perfect Aryan type, yet soft, well-fed and circumcised... $\endgroup$
    – AlexP
    Commented Dec 17, 2021 at 15:27
  • $\begingroup$ Suppose they notice that the assassin had a lot of tech made in China. Maybe some Russian stuff too - a Modernised AK47? They might conclude that the war would be won by an Eastern power. If they decide to pre-empt this by bringing forward their Eastern Front plans and attack Russia early in the war instead of waiting until they'd secured Europe, that could change a lot of their history... $\endgroup$ Commented Feb 4, 2022 at 13:21
  • $\begingroup$ @AlexP, just to be a wet noodle, there are people that get circumcised for non-religious reasons 🙂. But still. (OTOH, maybe he had a star-of-David under his shirt. There are less ambiguous, but still subtle, ways to say "Jew". Or what if he was trans...) $\endgroup$
    – Matthew
    Commented Feb 4, 2022 at 16:23
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    $\begingroup$ @Matthew: Yes, that is the point. As far as I understand most Americans are. But in Europe in the 1940s it was rather a rare occurrence for Christians. $\endgroup$
    – AlexP
    Commented Feb 4, 2022 at 16:34
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    $\begingroup$ @Matthew: Actually, what I was implying is that the Nazis, being Nazis, would think that in the far future the Jews has won. (The assassin is obviously not an ethnic Jew, from their point of view -- they believed that they had a way to tell apart Jews from non-Jews just from their physical measurements. That's why the answer says "Aryan type". The Nazis had this stupid belief that nationality and ideology are somehow linked with biology.) $\endgroup$
    – AlexP
    Commented Feb 4, 2022 at 17:07
  • Gun.

    I am quite sure that whatever gun the wannabe assassin carried it was pretty much the same as what guns they had in the 1940s. There is nothing to reverse engineer.

    Except maybe the materials, if the gun has some parts made of modern polymers. It wouldn't do them much good, though. They already knew what a polymer is, and they already had some pretty nifty polymers, such as, for example, plexiglas (aka acrylic glass).

  • Phone.

    The essential parts of modern smartphone cannot be reverese engineered with 1940s technology; they would even be hard pressed to realize it was a radio communication device -- they had very limited capabilities of detecting electromagnetic waves in the relevant frequency ranges. The microprocessor and memory would be complete mysteries; chances are they would destroy them while trying to see how they worked.

    The battery of the smart phone, they could understand what it did spend a lot of money and effort trying (fruitlessly) to understand how it worked.

    The screen... That depends on the screen. For a cheap backlit screen they would understand the lighting. For an OLED screen, nothing. It's way beyond what they knew.

  • Nvg.

    I have no idea what an nvg is.

    If you mean a night vision goggle, they already had such devices.

  • $\begingroup$ that largely depends on the gun, an AK could help them improve automatic weapon technology. especially considering how easy it is to copy. and a more modern night vision goggle could lead the mt far more effective photocathode materials, making scopes that work in any light unlike what they had. $\endgroup$
    – John
    Commented Dec 17, 2021 at 0:26
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    $\begingroup$ @John: The AK-47 is based on the German StG 44, which was already in development since 1940. But yes, in principle it could teach them that perfect is the enemy of good. $\endgroup$
    – AlexP
    Commented Dec 17, 2021 at 0:34
  • $\begingroup$ based but drastically improved, mostly in simplicity and ease of manufacture which would be BIG improvements for the germans. $\endgroup$
    – John
    Commented Dec 17, 2021 at 0:37
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    $\begingroup$ They could probably figure out that the silicon was a semiconductor, which would be baffling, they could not detect doping. $\endgroup$
    – Mary
    Commented Dec 17, 2021 at 3:24
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    $\begingroup$ The backlight in an old tech LCD screen is LED, so that would be as mysterious in the 1940s as the microchips and the LCD panel itself. Even a microscope capable of resolving the nanometer-scale circuit elements in a decapped chip likely didn't exist before 1945 -- so even if they could open the chips without physically destroying them, they'd have virtually no chance to figure out that they're electronic devices. $\endgroup$
    – Zeiss Ikon
    Commented Dec 17, 2021 at 17:51

Focusing on the phone, If there was a demonstration of the capability, perhaps recorded on film, that showed the phone playing music, videos, or animated games, or even the calculator it would immediately stimulate tremendous interest. For example, just showing computations of sines, cosines, logarithms etc. out to 12 or 15 decimal places would reveal a lot of potential. But even assuming the battery had depleted a tremendous amount could be learned using the technology of the time, especially in material science. Even if the phone had been smashed, one could imagine a dedicated laboratory being set up to study the technologies.

With an optical microscope with a 50 or 100x objective (reasonable at the time), they would be able to understand pixels, see the interconnections and probably deduce photolithography was used. They would marvel at the cameras, and immediately understand what they were and conclude that some type of “artificial retina” had been constructed.

With the printed circuit board they would recognize the solder, but not the lamination technology, but would understand it is a lamination technology and understand that circuits could be made, they would understand resistors, capacitors etc and be able to measure them.

Integrated circuits would be beyond them initially, but they would identify the silicon as an extremely pure materials and would point them in a good direction to pursue. Again, they probably would recognize that a lithographic process had been used to define features for the printed circuit board.

They would probably recognize the LED as some type of lighting device since it has a lens, and since it has two wires may be able to recognize it as a diode, perhaps light it up and eventually identify the materials that was made of. Even things like the insulation on the wires and types of wires would be of interest.

The battery would be of tremendous interest and since it is clearly labeled battery with specifications, they would know exactly what it is. Although, they would probably be puzzled as to why it was made in China. There would be other written clues inside the phone. Just knowing that a lithium-ion battery could be made would give a large head start.

To keep this reasonable length, in the 1940’s there were a lot of very bright people, a lot of good basic science, physics and chemistry, and a phone would reveal a tremendous amount of material science, optics, assembly techniques, and ideas of what is possible.

The ideas behind the field effect transistor predate WWII, and the junction transistor was right around the corner in 1947, so in the right hands a phone would reveal a lot. Initially, just understanding the quality of the materials and what the materials were would really jump start a lot of interesting technologies.

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    $\begingroup$ They had television cameras in the 1940s. (The 1936 Berlin Summer Olympic games were the first large scale sporting event to be televised.) So they already knew how to make an "artificial retina". $\endgroup$
    – AlexP
    Commented Dec 17, 2021 at 1:39
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    $\begingroup$ I'd correct it myself, but I find it too funny to alter it. I mean the "just showing computations of sins" $\endgroup$ Commented Dec 17, 2021 at 2:03
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    $\begingroup$ While they could gather a plethora of interesting ideas and concepts to explore, they would need 15 to 25 years to develop the base science and necessary technology to make something useful out of all the ideas this reverse engineering has given. And since the assassin failed to kill Hitler, Germany loses the war in early 1945, so they have no time to do it. Another thing would be if the assassin had succeeded and a competent leader had taken the reins of the country instead. $\endgroup$
    – Rekesoft
    Commented Dec 17, 2021 at 9:27
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    $\begingroup$ I think they should be able to reverse engineer charge parameters, for starters they may be printed on power chip (in the form of 5V 2A). Then they can use it for advanced computations. $\endgroup$
    – alamar
    Commented Dec 17, 2021 at 12:49
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    $\begingroup$ @AlexP Luckily, the phone already contains smart charging circuitry, and the charger just have to supply a +5V. Germans can surely arrange that. Charging works against a regular USB port which is not very smart as they go. $\endgroup$
    – alamar
    Commented Dec 17, 2021 at 15:48

Some ideas

A modern, high-capacity semi-automatic would certainly be a step forward compared to then-current designs. The positioning of the magazine release, double-stack magazines, a trigger guard obviously designed for a two-handed grip, ...

Exhibit A: The Luger P08 with eight rounds in the magazine.
Exhibit B: The Colt M1911, great stopping power but just seven rounds and quite a kick.
Exhibit C: The Browning High Power.
Exhibit D: The Mk23 with many of the optional extras.
Imagine someone from the Reichssicherheitsdienst going "Build something like that for us."

If the assassin has night-vision gear, how about a modern tactical vest? The arrangement of the pouches might strike them as sensible and replace the old-fashioned LBE.

Lots of little detail improvements they could copy.

No practical effect

Nothing that would make a difference on a large scale (e.g. introducing transistors on sort-of-microchips) will be reverse-engineered and fielded in time before the Soviet tank armies overrun the Eastern front.

  • $\begingroup$ The double-stack magazine was available as early as 1896 when it appeared in the C96 Mauser. Depending on the modern pistol, you can find the magazine release in the exact same locations as it was on older firearms: the only real difference between magazine release on something like a Glock-19 and the Luger P08 is the shape of the button. The flattened recurved front of the trigger guard is relatively newer thing, but the M1911 and several other firearms predating WW2 had flat fronted trigger guards, and the necessity of it is disputed anyway. So really, a modern pistol brings nothing new. $\endgroup$ Commented Feb 4, 2022 at 20:49
  • $\begingroup$ @KeithMorrison, I mentioned the Browning HP as an example. The modern pistol is different from the guns then in service, as exemplified by the Luger and Colt. It is about getting all the little details into one gun. $\endgroup$
    – o.m.
    Commented Feb 5, 2022 at 8:47
  • $\begingroup$ a modern sidearm isn't different from the pistols that were or had been in service previously, so, materials aside, it would provide nothing new or innovative that would make a difference. $\endgroup$ Commented Feb 8, 2022 at 17:37
  • $\begingroup$ @KeithMorrison, example D differs from the service pistols then in general issue, as listed in my examples A and B. Just because every single aspect could be found somewhere, the combination makes a difference. $\endgroup$
    – o.m.
    Commented Feb 8, 2022 at 18:06

Here is a frame challenge.

The question asks about modern technology, as if modern technology would be 2021 level technology. Inventing time travel requires technology decades, centuries, millenia, tens of millennia, etc. beyond the technology of 2021 - or considering how late in 2021 it is, let us say the crude technology of 2022.

Humans in the year 2022 with 2022 technology will never be able to invent time travel. Not in any plausible story.

So assassins sent in the past to assassinate someone will use weapons far more advanced than anything we can make in 2022, possibly more than we can imagine.

Possibly the assassin will simply arrive in the past halfway around the world from Hitler, think a command such as "Die! Hitler, Die!" and his technology will kill Hitler in a way that German doctors will be unable to understand, and which the assassin will not bother to think about since it is so simple and basic when he comes from.

The only possible way for a time traveling assassin to use incredibly backwards and primitive 2022 technology to assassinate someone in the past would be if the time traveler was from 2022 and aliens from outer space with technoology thousands or millions of years more advanced arrived on Earth and gave time machines to humans. Or maybe time travelers from the distant future arrived and gave time machines to humans.

And if humans asked the aliens or time travelers from the future if they could use the time machines to assassinate evil persons in the past, and the visitors said "Sure. Why not? What's the worst thing that could possibly happen if you try that?", and the 2022 humans couldn't think of anything particularly bad that could happen, then I guess an assassin could be sent into the past with primitive, backwards, crude, 2022 level technology.

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    $\begingroup$ The 2021 gear and clothes could also be the result of sloppy preparation. Say the time traveler starts out his noble mission to kill AH in the year 2610 or so.. to be able to move around in the target time, he would have to impersonate someone contemporary.. the historian who was the clothing and weaponry adviser for the mission made a small mistake.. all stuff is 80 years off.. $\endgroup$
    – Goodies
    Commented Dec 17, 2021 at 19:21

Guns could provide a new design, although honestly it's not much (if any) improvement. Anything electronic very unlikely.

While it is possible (with enormous care) to reverse engineer electronics by stripping the cover material and taking photos of each layer, here they've got one shot and just about any mistake dooms the entire enterprise. Plus, even if you do somehow reverse engineer the chips you don't have anything to run on it. They've got absolutely no way to save the software off the thing, let alone any needed firmware etc.

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    $\begingroup$ Even if you went back and handed them complete, step-by-step instructions, they don't have the ~10nm precision manufacturing capability to reproduce the chip. To build that, they would need factories controlled by (less sophisticated, larger) computer chips, which would require yet other factories... it's a big industrial pyramid to climb. $\endgroup$
    – Cadence
    Commented Dec 17, 2021 at 0:48
  • $\begingroup$ The had no microscopes which could even see the individual transistors and traces in the modern microchips... $\endgroup$
    – AlexP
    Commented Dec 17, 2021 at 1:32

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