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I've always been curious how far we could push "mechanical computation." Seems like even an operation as simple as multiplication requires tons of metal. If I w

I've always been curious how far we could push "mechanical computation." Seems like even an operation as simple as multiplication requires tons of metal. If I wanted to compute, say, a SHA2 hash or an Ed25519 signature with zero electricity, would I need a room-sized machine?

pgboswell 5y ago
For sure - at least with the parts in their current form. A simple flip-flop takes up a minimum space of about 30 cm x 30 cm. But I wonder how small these parts could get. Like, what if spintronics was invented in the 19th century instead of the 21st century? Would Moore's law have applied to mechanical transistors?
- dekhn 5y ago
  See https://en.wikipedia.org/wiki/There%27s_Plenty_of_Room_at_the_Bottom https://en.wikipedia.org/wiki/There%27s_Plenty_of_Room_at_th... and https://en.wikipedia.org/wiki/Engines_of_Creation https://en.wikipedia.org/wiki/Engines_of_Creation TL;DR we're nowhere close to exploiting the full potential of nanoscale mechanical systems.
  - mdaniel 5y ago
    For those who don't click on the Engines of Creation link, be aware that at the bottom of that page is a PDF link to the gratis version of Engines of Creation 2.0 from 2007: https://web.archive.org/web/20140810022659/http://www1.appstate.edu/dept/physics/nanotech/EnginesofCreation2_8803267.pdf https://web.archive.org/web/20140810022659/http://www1.appst... Since I just now learned about that link, I haven't read the book to know, but I have always been interested in finding out if the ability to create smaller and smaller machines is possible by having an outer machine which manufactures an inner, smaller, copy of itself, apply the process of induction, define the termination criteria, ..., profit! Or, maybe I'm thinking about the problem all wrong -- it's not the actual construction machinery that's the problem, it's providing the input materials to each step (gears, levers, fasteners, wiring(?), etc) There's a Factorio-clone hiding in this problem ...
    - lazide 5y ago
      The issue is that scaling does not produce linear effects as you go down (or up) for a number of reasons. What works at the meter scale doesn’t work at the millimeter scale, which doesn’t work at the micrometer scale, etc. So you end up having to learn an experiment at a more and more difficult to access scale to figure out how to make something actually work. That’s real life anyway.
    - rusticpenn 5y ago
      MEMS started out to cater to this dream, unfortunately problems like stiction (https://www.sciencedirect.com/topics/engineering/stiction https://www.sciencedirect.com/topics/engineering/stiction) have been blockers until now.
    - AriedK 5y ago
      Thanks for the recommendation. That cover though, is that topology specific to a coronavirus or do more viruses share it? Especially since the Pfizer/Biontech and Moderna vaccines deploy nano-particles for delivering their payload.
    - dekhn 5y ago
      the reality is that it turned out to be easier to make things with lithography, and we don't need to pantograph our way to the bottom (whew!). Many cell phones now have sensors that are mems-based, built using lithography (accelerometers being the best example). In many senses, we've started to achieve the goals of the book. You might also enjoy Diamond Age.
      - mdaniel 5y ago
        I did enjoy Diamond Age, maybe I should reread it! It was the first time I had ever heard of "reversible computing" and (ahem) I still don't understand it, but it's good to know such a thing exists I'm about 175 pages into that PDF and am now sorry that I drew attention to it. I was beguiled by the name recognition and the snazzy title, but I find the text filled with hand-wavery and aspirational thinking, and it also seems to focus a lot more on DNA than I would have expected I also find even their aspirations suspicious that any such machinery could ever possibly exist to just tweezer atoms around like marbles and voila gold from lead!
tlb 5y ago
Mechanical Turing machines can be small, such as: https://hackaday.com/2018/03/08/mechanical-wooden-turing-machine/ https://hackaday.com/2018/03/08/mechanical-wooden-turing-mac... They will take a long time to compute something like SHA2
nynx 5y ago
If you could build mechanisms atom-by-atom, you could make reversible mechanical computers that are orders of magnitude faster than what we have today.
- pgboswell 5y ago
  This is very interesting. Why would they be faster?
  - zardo 5y ago
    Building at the molecular scale you can achieve extremely low friction coefficients in the moving parts. Inertia also gets extremely low, and material strengths tend toward their theoretical values. Of course electronics aren't standing still, but resistance tends to get harder to deal with as feature sizes decrease.
    - PeterisP 5y ago
      What I've always wondered is that wouldn't very tiny molecular mechanisms get problems with "accidental welding" since a part could be permanently destroyed by a few molecular bonds forming or breaking and (IMHO - this is my guess/assumption) such events would be likely at e.g. room temperature.
      - db48x 5y ago
        Unless designed well, yes. Parts that move relative to each other need to be designed so that unwanted bonds are unlikely to form. This generally means designing them so that unwanted bonds are less energetically favorable than the bonds they start out with. Of course, as temperature rises, the chance of breaking existing bonds rises, as does the chance of forming new unwanted bonds.
  - dang 5y ago
    Sorry that HN's software rate limited your account! New accounts are subject to a few extra restrictions, and it always makes me sad when a project creator shows up and gets hit by those (I'm a mod here). That's not at all a case that we're trying to restrict! I've marked your account legit so this will not happen to you again, and I've approved your comments that got throttled, so they're up now. Welcome to HN and congratulations on this exceedingly cool work.
nxpnsv 5y ago
I guess you can do it with pen and paper and patience...
RandallBrown 5y ago
You should read Neal Stephenson's Diamond Age. It's in an alternate future where they use mechanical computers.
- mcp_ 5y ago
  The Difference Engine by Bruce Sterling and William Gibson would be a good read on that topic too.
Laremere 5y ago
You can hold a mechanical calculator in your hand, so I imagine if an industry of effort on perfecting mechanical computation, it could get quite small: https://en.wikipedia.org/wiki/Curta https://en.wikipedia.org/wiki/Curta
carapace 5y ago
Mechanical multiplication is easy: https://en.wikipedia.org/wiki/Sliderule https://en.wikipedia.org/wiki/Sliderule See more generally: https://en.wikipedia.org/wiki/Nomogram https://en.wikipedia.org/wiki/Nomogram
AriedK 5y ago
I was blown away (no pun intended) by the mechanical analog computers used fire control systems on battle ships: https://arstechnica.com/information-technology/2020/05/gears-of-war-when-mechanical-analog-computers-ruled-the-waves/ https://arstechnica.com/information-technology/2020/05/gears... This was 3000 pounds for calculating a shell trajectory (with a good number of parameters).
- hypertele-Xii 5y ago
  Here's a video detailing some of the math and mechanisms used. https://www.youtube.com/watch?v=s1i-dnAH9Y4 https://www.youtube.com/watch?v=s1i-dnAH9Y4

pgboswell 5y ago

For sure - at least with the parts in their current form. A simple flip-flop takes up a minimum space of about 30 cm x 30 cm. But I wonder how small these parts could get. Like, what if spintronics was invented in the 19th century instead of the 21st century? Would Moore's law have applied to mechanical transistors?

dekhn 5y ago
See https://en.wikipedia.org/wiki/There%27s_Plenty_of_Room_at_the_Bottom https://en.wikipedia.org/wiki/There%27s_Plenty_of_Room_at_th... and https://en.wikipedia.org/wiki/Engines_of_Creation https://en.wikipedia.org/wiki/Engines_of_Creation TL;DR we're nowhere close to exploiting the full potential of nanoscale mechanical systems.
- mdaniel 5y ago
  For those who don't click on the Engines of Creation link, be aware that at the bottom of that page is a PDF link to the gratis version of Engines of Creation 2.0 from 2007: https://web.archive.org/web/20140810022659/http://www1.appstate.edu/dept/physics/nanotech/EnginesofCreation2_8803267.pdf https://web.archive.org/web/20140810022659/http://www1.appst... Since I just now learned about that link, I haven't read the book to know, but I have always been interested in finding out if the ability to create smaller and smaller machines is possible by having an outer machine which manufactures an inner, smaller, copy of itself, apply the process of induction, define the termination criteria, ..., profit! Or, maybe I'm thinking about the problem all wrong -- it's not the actual construction machinery that's the problem, it's providing the input materials to each step (gears, levers, fasteners, wiring(?), etc) There's a Factorio-clone hiding in this problem ...
  - lazide 5y ago
    The issue is that scaling does not produce linear effects as you go down (or up) for a number of reasons. What works at the meter scale doesn’t work at the millimeter scale, which doesn’t work at the micrometer scale, etc. So you end up having to learn an experiment at a more and more difficult to access scale to figure out how to make something actually work. That’s real life anyway.
  - rusticpenn 5y ago
    MEMS started out to cater to this dream, unfortunately problems like stiction (https://www.sciencedirect.com/topics/engineering/stiction https://www.sciencedirect.com/topics/engineering/stiction) have been blockers until now.
  - AriedK 5y ago
    Thanks for the recommendation. That cover though, is that topology specific to a coronavirus or do more viruses share it? Especially since the Pfizer/Biontech and Moderna vaccines deploy nano-particles for delivering their payload.
  - dekhn 5y ago
    the reality is that it turned out to be easier to make things with lithography, and we don't need to pantograph our way to the bottom (whew!). Many cell phones now have sensors that are mems-based, built using lithography (accelerometers being the best example). In many senses, we've started to achieve the goals of the book. You might also enjoy Diamond Age.
    - mdaniel 5y ago
      I did enjoy Diamond Age, maybe I should reread it! It was the first time I had ever heard of "reversible computing" and (ahem) I still don't understand it, but it's good to know such a thing exists I'm about 175 pages into that PDF and am now sorry that I drew attention to it. I was beguiled by the name recognition and the snazzy title, but I find the text filled with hand-wavery and aspirational thinking, and it also seems to focus a lot more on DNA than I would have expected I also find even their aspirations suspicious that any such machinery could ever possibly exist to just tweezer atoms around like marbles and voila gold from lead!

tlb 5y ago

Mechanical Turing machines can be small, such as: https://hackaday.com/2018/03/08/mechanical-wooden-turing-machine/ https://hackaday.com/2018/03/08/mechanical-wooden-turing-mac... They will take a long time to compute something like SHA2

nynx 5y ago

If you could build mechanisms atom-by-atom, you could make reversible mechanical computers that are orders of magnitude faster than what we have today.

pgboswell 5y ago
This is very interesting. Why would they be faster?
- zardo 5y ago
  Building at the molecular scale you can achieve extremely low friction coefficients in the moving parts. Inertia also gets extremely low, and material strengths tend toward their theoretical values. Of course electronics aren't standing still, but resistance tends to get harder to deal with as feature sizes decrease.
  - PeterisP 5y ago
    What I've always wondered is that wouldn't very tiny molecular mechanisms get problems with "accidental welding" since a part could be permanently destroyed by a few molecular bonds forming or breaking and (IMHO - this is my guess/assumption) such events would be likely at e.g. room temperature.
    - db48x 5y ago
      Unless designed well, yes. Parts that move relative to each other need to be designed so that unwanted bonds are unlikely to form. This generally means designing them so that unwanted bonds are less energetically favorable than the bonds they start out with. Of course, as temperature rises, the chance of breaking existing bonds rises, as does the chance of forming new unwanted bonds.
- dang 5y ago
  Sorry that HN's software rate limited your account! New accounts are subject to a few extra restrictions, and it always makes me sad when a project creator shows up and gets hit by those (I'm a mod here). That's not at all a case that we're trying to restrict! I've marked your account legit so this will not happen to you again, and I've approved your comments that got throttled, so they're up now. Welcome to HN and congratulations on this exceedingly cool work.

nxpnsv 5y ago

I guess you can do it with pen and paper and patience...

RandallBrown 5y ago

You should read Neal Stephenson's Diamond Age. It's in an alternate future where they use mechanical computers.

mcp_ 5y ago
The Difference Engine by Bruce Sterling and William Gibson would be a good read on that topic too.

Laremere 5y ago

You can hold a mechanical calculator in your hand, so I imagine if an industry of effort on perfecting mechanical computation, it could get quite small: https://en.wikipedia.org/wiki/Curta https://en.wikipedia.org/wiki/Curta

carapace 5y ago

Mechanical multiplication is easy: https://en.wikipedia.org/wiki/Sliderule https://en.wikipedia.org/wiki/Sliderule See more generally: https://en.wikipedia.org/wiki/Nomogram https://en.wikipedia.org/wiki/Nomogram

AriedK 5y ago

I was blown away (no pun intended) by the mechanical analog computers used fire control systems on battle ships: https://arstechnica.com/information-technology/2020/05/gears-of-war-when-mechanical-analog-computers-ruled-the-waves/ https://arstechnica.com/information-technology/2020/05/gears... This was 3000 pounds for calculating a shell trajectory (with a good number of parameters).

hypertele-Xii 5y ago
Here's a video detailing some of the math and mechanisms used. https://www.youtube.com/watch?v=s1i-dnAH9Y4 https://www.youtube.com/watch?v=s1i-dnAH9Y4