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Somehow i think this field should be researched more thoroughly. Imagine a plan B for complete societal collapse, or war like situations where digital systems a

Somehow i think this field should be researched more thoroughly. Imagine a plan B for complete societal collapse, or war like situations where digital systems are not available, yet some basic agricultural computations or means of communication can be achieved purely by mechanical computing systems. For instance typing on a typewriter (or predefined message buttons) while spinning a basic motor could create radio waves; similarly something could receive such messages and decode them. Perhaps even for space com such a device could be used as backup. If anything it might be interesting to have knowledge about.

akeck 5y ago
Go back to artillery, etc. mechanical targeting in WWII, just before electric computers came onto the scene. Feynman talks about those mechanical computers in Surely You're Joking Mr. Feynman. Apparently, you can do mechanical integrals and derivatives with specially-shaped non-round gears.
- neltnerb 5y ago
  Not sure about derivatives, but an integrator is just a rotating disk with a ball on it, both spherical. The ball rolls over the disk from friction, and the spinning is the magnitude of the output integral. The input function is the position of the ball relative to the center of the disk. If the ball is at the center of the disk it doesn't move, if it moves positive the ball spins up, if it moves negative the ball spins down. The overall rotation of the ball is essentially the integral. You can also do almost this to make multipliers by varying the speed of the disk. These mechanical computers were used until the mid 1900s.
WJW 5y ago
You might be interested in the analog computers that were used to compute tide tables back in the day. It's quite fascinating how they even managed to do basic Fourier transforms without electricity: https://www.youtube.com/watch?v=IgF3OX8nT0w https://www.youtube.com/watch?v=IgF3OX8nT0w
Koshkin 5y ago
> complete societal collapse, or war like situations where digital systems are not available If something like that happens all you will want is clean water, some basic food, and a weapon to defend yourself, your family, and small, closely-knit community you will not have a chance of survival without. And yes, you will quickly forget about "space com."
- waste_monk 5y ago
  Putting aside communications with other survivors / between settlements, there's a very good reason to want to receive satellite communications: weather satellites. You probably won't have a weather radar at your post-apocalyptic settlement, but if you can receive NOAA imagery (or whatever suits e.g. Himawari-8 if you're in the APAC region like me) you can at least see if there's any nasty storms coming up and hopefully do some basic agricultural forecasting. I do agree that it's something you should worry about once your basic survival, shelter, and community needs are secure. However given you would need a reasonable technology base to manufacture mechanical computers, I think the "dependency management" would naturally sort itself out. This also assumes that the satellites haven't been shot down during whatever disaster caused the complete failure of electrical computing, and that you can actually build a mechanical computer that can receive the broadcast and usefully render the images.
  - Someone 5y ago
    Do these satellites automatically correct for orbital decay (https://en.wikipedia.org/wiki/Orbital_decay https://en.wikipedia.org/wiki/Orbital_decay) and collision avoidance or does that require commands from the ground? Reading https://www.swpc.noaa.gov/impacts/satellite-drag https://www.swpc.noaa.gov/impacts/satellite-drag, I get the impression that involves ground control (because of those complicated models that get updated all the time) So, how long will these satellites stay up there without ground control?
    - waste_monk 5y ago
      My understanding is that (at least for Himawari-8) it is geostationary at a high enough altitude (apogee and perigee) that it should be good for at least a few decades - apparently you actively have to boost geostationary satellites out to a retirement orbit so they don't crowd up the prime real estate. That said, the imaging sensors have a limited lifetime (the satellite platform is designed to be good for ~15 years but the sensor package limits the mission lifetime to 8 years).
PeterisP 5y ago
Digital processors are not needed for "basic agricultural computations" nor for communication. A ham radio can work and transmit/receive information without any typewriter-like automation (both microphones and manual Morse code don't require computation) and you can do all the calculations needed for ordinary agriculture on an abacus if needed. In any case, the extremely precise machining in large quantities required for any reasonable mechanical computer means that it's not a low-tech or high-reliability replacement for electronic computers, it's a very high-tech future solution to the limitations of current electronic devices. We can't make such devices now, we'll hopefully be barely able to make them in the future, but in the case of infrastructure collapse we'll lose the capability to make these advanced mechanical devices before losing digital devices. And nowadays computing is so ubiquitous, that every horrible scenario would still leave us with huge amounts of computing power lying around. Soldering together devices out of scrap electronic components is a much more reasonable way of doing post-apocalyptic computation than any of this mechanical computing tech; If there was a real need, nowadays you could extract a dozen usable processors from a crashed car or modern kitchen - even excluding computers and smartphones, so many modern devices have random processor(s) that are more powerful than what people used as their primary computers some decades ago. Things like wireless headphones and washing machines have chips that could be sufficient for so many computing needs. Apple's Lightning to HDMI cable has a powerful ARM processor inside. etc, etc.

akeck 5y ago

Go back to artillery, etc. mechanical targeting in WWII, just before electric computers came onto the scene. Feynman talks about those mechanical computers in Surely You're Joking Mr. Feynman. Apparently, you can do mechanical integrals and derivatives with specially-shaped non-round gears.

neltnerb 5y ago
Not sure about derivatives, but an integrator is just a rotating disk with a ball on it, both spherical. The ball rolls over the disk from friction, and the spinning is the magnitude of the output integral. The input function is the position of the ball relative to the center of the disk. If the ball is at the center of the disk it doesn't move, if it moves positive the ball spins up, if it moves negative the ball spins down. The overall rotation of the ball is essentially the integral. You can also do almost this to make multipliers by varying the speed of the disk. These mechanical computers were used until the mid 1900s.

WJW 5y ago

You might be interested in the analog computers that were used to compute tide tables back in the day. It's quite fascinating how they even managed to do basic Fourier transforms without electricity: https://www.youtube.com/watch?v=IgF3OX8nT0w https://www.youtube.com/watch?v=IgF3OX8nT0w

Koshkin 5y ago

> complete societal collapse, or war like situations where digital systems are not available If something like that happens all you will want is clean water, some basic food, and a weapon to defend yourself, your family, and small, closely-knit community you will not have a chance of survival without. And yes, you will quickly forget about "space com."

waste_monk 5y ago
Putting aside communications with other survivors / between settlements, there's a very good reason to want to receive satellite communications: weather satellites. You probably won't have a weather radar at your post-apocalyptic settlement, but if you can receive NOAA imagery (or whatever suits e.g. Himawari-8 if you're in the APAC region like me) you can at least see if there's any nasty storms coming up and hopefully do some basic agricultural forecasting. I do agree that it's something you should worry about once your basic survival, shelter, and community needs are secure. However given you would need a reasonable technology base to manufacture mechanical computers, I think the "dependency management" would naturally sort itself out. This also assumes that the satellites haven't been shot down during whatever disaster caused the complete failure of electrical computing, and that you can actually build a mechanical computer that can receive the broadcast and usefully render the images.
- Someone 5y ago
  Do these satellites automatically correct for orbital decay (https://en.wikipedia.org/wiki/Orbital_decay https://en.wikipedia.org/wiki/Orbital_decay) and collision avoidance or does that require commands from the ground? Reading https://www.swpc.noaa.gov/impacts/satellite-drag https://www.swpc.noaa.gov/impacts/satellite-drag, I get the impression that involves ground control (because of those complicated models that get updated all the time) So, how long will these satellites stay up there without ground control?
  - waste_monk 5y ago
    My understanding is that (at least for Himawari-8) it is geostationary at a high enough altitude (apogee and perigee) that it should be good for at least a few decades - apparently you actively have to boost geostationary satellites out to a retirement orbit so they don't crowd up the prime real estate. That said, the imaging sensors have a limited lifetime (the satellite platform is designed to be good for ~15 years but the sensor package limits the mission lifetime to 8 years).

PeterisP 5y ago

Digital processors are not needed for "basic agricultural computations" nor for communication. A ham radio can work and transmit/receive information without any typewriter-like automation (both microphones and manual Morse code don't require computation) and you can do all the calculations needed for ordinary agriculture on an abacus if needed. In any case, the extremely precise machining in large quantities required for any reasonable mechanical computer means that it's not a low-tech or high-reliability replacement for electronic computers, it's a very high-tech future solution to the limitations of current electronic devices. We can't make such devices now, we'll hopefully be barely able to make them in the future, but in the case of infrastructure collapse we'll lose the capability to make these advanced mechanical devices before losing digital devices. And nowadays computing is so ubiquitous, that every horrible scenario would still leave us with huge amounts of computing power lying around. Soldering together devices out of scrap electronic components is a much more reasonable way of doing post-apocalyptic computation than any of this mechanical computing tech; If there was a real need, nowadays you could extract a dozen usable processors from a crashed car or modern kitchen - even excluding computers and smartphones, so many modern devices have random processor(s) that are more powerful than what people used as their primary computers some decades ago. Things like wireless headphones and washing machines have chips that could be sufficient for so many computing needs. Apple's Lightning to HDMI cable has a powerful ARM processor inside. etc, etc.