Ask HN: Building a Computer in Jesus's Time
I keep thinking about if I suddenly went back in time, how hard would it be to make a computer?
Could I at least make a vacuum tube?
Could I at least make a vacuum tube?
[0] https://en.wikipedia.org/wiki/Antikythera_mechanism
[1] https://www.age-of-the-sage.org/archaeology/antikythera_mech...
https://en.wikipedia.org/wiki/Z1_%28computer%29?wprov=sfla1
That said, you would need lots of flexible ferrous metal and a source of electricity, probably large voltaic piles. And you would need to find a way to produce and insulate large amounts of wire.
[0] https://www.jstor.org/stable/24989059?seq=1
[1] https://www.i-programmer.info/news/112-theory/7370-pulleys-a...
Making the metal parts was well within their power. At least the shapes, though maybe not the alloys that we would use. Getting that shape inside the blown glass might be harder, given the tech of the day.
Getting a vacuum in it might be the hardest step. In fact, I don't know that it was possible at all, given the tech they had available. The first vacuum pump was in 1654.
Certainly within the history of China, India, and various African, Greek, and Middle Eastern cultures, complex mechanical devices with sequencers and even primitive logic gates were being implemented. See, for example https://en.wikipedia.org/wiki/Ismail_al-Jazari as well as https://en.wikipedia.org/wiki/Tang_dynasty#Alchemy,_gas_cyli... as examples where societies combined the necessary wealth, stability, education, social and religious culture to build very impressive mechanical devices.
I'm going to assume also that you have The Knowledge (https://www.amazon.com/gp/product/B00DMCV5YS) all the way up to basic electronics.
At that point you would have everything required to gather people and money and time to build a relay- or vacuum-tube based computer. I recommend reading the early sections of The Idea Factory https://www.amazon.com/Idea-Factory-Great-American-Innovatio... describing what the early Bell Labs was like. Many modern innovations came from itinerant scientists who interned at Bell Labs, learned to make vacuum tubes by hand (IE, blowing air precisely into molten glass, and sealing the various electronics in place) and then left to found companies that utilized tubes (for example, Beckman went through this process and used the acquired knowledge to build a vacuum-tube based amplifier which was critical to the modern pH meter).
Now, a few challenges. Since you're just dropping back into a society that hasn't undergone an industrial revolution, you don't have a bunch of useful cross-supporting things like a healthy industry that makes high quality alloy steel for you, or optics companies which design and sell sophisticated lens assemblies for high quality telescopes to debug your work, or electronics companies pumping out millions of standard resistors with tight variances, etc. Without those, many steps that would be trivial would instead take extended time. Also, the absence of a statistical quality culture (see Deming) and the fact that most components will be built by hand by artisans means that your computer will not be very reliable (producing incorrect results, or breaking often).
On top of that, you'll probably face skepticism because your early computers won't be able to do anything useful compared to skilled humans. You would probably do best by finding a local military leader and convincing them you could help with ballistics calculations...