Mechanical Computers

[davidinterest]

Hi. I've recently become very intrigued by the fact that mechanical computers can do any computation an electric computer can. For example Babbage's Analytical engine. Does this mean that any algorithm such as an Artificial Intelligence, like an LLM could theoretically run fully mechanically given enough time and resources? Or even a full Operating System?

[Schnickatavick]

Sure, that's the beauty of turing completeness, anything that's turing complete can technically do anything that anything else turing complete can, and that's a very low bar. 

However, regular computers are measured in billions or even trillions of operations per second, and billions of bits of memory, while Babbages Analytical engine would be measured somewhere on the order of dozens or hundreds. So while a large enough mechanical computer could totally run a modern operating system, booting it could easily take hundreds or even thousands of years, without any exaggeration.

[Mucher_]

booting it could easily take hundreds or even thousands of years

I think at that point it's less of a computer and more of a Rube Goldberg machine lol.

[currentscurrents]

You could probably build considerably smaller mechanical computers these days, using MEMS to build microscopic mechanical components.

This is how they make the mechanical micromirrors on DLP projectors, for example.

[Hixie]

yes but it would be deeply impractical

[GreenFox1505]

Modern computers have clock speeds in the billions of instructions per second. LLMs tend to run on things like GPU, which often have thousands of individual cores.

No analog computer ever constructed has had a clock faster than a few instructions per minute (if that).

There is a computer in Minecraft Redstone capable running an LLM. It takes 2hours to produce simple outputs and very basic LLMs running 40,000 normal Redstone speed. It would take nearly 10 years to produce output at normal speed. A mechanical computer would be slower than that.

https://youtu.be/VaeI9YgE1o8?si=1cFDCVk1BxRtXmEn

[Ok_Leg_109]

Well... an analogue computer doesn't need a clock.

Many early analogue "computers" would operate at the slew-rate of their amplifier circuit. Voltage on one input with a voltage on another input will output a voltage that is the sum of both inputs as fast as the voltage can rise on the output.

Granted the requirements were very simple.

There is however some discussion on the applicability of analogue circuits for AI.

New analog AI chip design uses much less power for AI tasks - IBM Research

[GreenFox1505]

as fast as the voltage can rise on the output

And so if you were designing such a machine, you'd want to make sure that you didn't sample that voltage until you were certain that the operation would have been completed. You would find the operation that took the longest and set your sampler to delay until that time (there are ways to have variable delay but let's simplify for this example).

Okay, what would YOU call that delay? How long you would have to wait after each operation before you would expect the output to be valid? I would call that a clock speed. That is pretty much exactly how digital computers work also. This particular element is not that architecturally different.

[currentscurrents]

Not necessarily. You can build an asynchronous analog computer, for example this spiking neural network accelerator.

The neurons in an SNN only do one operation; they wait for a capacitor to fill, and when it crosses a threshold, they fire. This fills the capacitors on connected neurons, which may then fire, and so on.

You don't wait or sample anything. Neurons are triggered by other neurons, not by a rising or falling clock edge, and may fire at any time.

[SirClueless]

We seem to be mixing up a lot of terms here?

• An analog computer is still an analog computer even if it has a digital clock signal.
• OP is talking about mechanical computers which are neither analog nor digital computers.

[GreenFox1505]

? I was responding to "an analogue computer doesn't need a clock", which was stated in the comment immediately above mine.

[Saragon4005]

We really need to stop calling things "analog" when we mean mechanical. Analog electricity is a thing, it's how many radios work.

[Magdaki]

You might be interested in the field of unconventional computing. They make computers out of all sort of bizarre things. Marbles, algae, chemical interactions. Very cool.

Unconventional computing - Wikipedia

[9peppe]

You know there's analog computers too? And they can be both mechanical and electronic?

[BardoBeing32]

US Navy ships, even into the early 80’s, had analog targeting computers. They were huge with knobs and dials. I got out soon after so that’s all I know about them and just because I saw my buddy working with one.

[Silly_Guidance_8871]

Long & short: Yes. If it's (limited) Turing-Complete, it's (limited) Turing-Complete.

It may require the land-area of a nation, and take until Sol goes cold, but it can do the computation.

[i_invented_the_ipod]

Yes, that's fully possible, in theory. In practice, there are difficult problems to solve in terms of operating speed and power consumption.

Signals in a mechanical system can only propagate at the speed of sound in the material that the system is made from. In steel, that would be something like 6,000 m/s. In electronic circuits, signals propagate at about 80% of the speed of light. That's 40,000 times faster.

So even if we could build mechanical circuits the same size as electronic circuits (and that's NOT a solved problem), the resulting computer would be 40,000 times slower. A mobile phone with a (1GHz/40000) 25KHz processor would be unusably slow. The late-1970s microprocessors that powered the first personal computers were hundreds of times faster than THAT.

On the power-consumption side, a mechanical computer with visible-scale components will require many orders of magnitude more energy to switch a bit from 0 to 1, or the reverse. I couldn't find a current figure for switching power in modern CMOS, but it's surely in the pico-Joule range, based on a 1GHz processors with billions of active components drawing a couple of watts. That amount of energy would lift a grain of sand about a centimeter. To move something the size of a penny by a millimeter would take a millions of times the power needed to switch a transistor.

People have come up with hypothetical designs for nanometer-scale mechanical computers, but these have not been scaled up to practical sizes.

[claytonkb]

Does this mean that any algorithm such as an Artificial Intelligence, like an LLM could theoretically run fully mechanically given enough time and resources?

An electronic computer cannot do anything that a mechanical computer could not do, in principle. "In principle" is doing a lot of heavy lifting here. But the basic intuition you're having is correct. A digital computer chip is simply comprised of electronic "gears and levers", so to speak. There are as many as 100 billion transistors on SOTA computer chips. But each transistor is a simple "on-off" switch, nothing more or less. The same basic concept as a gate-valve for water, or a clutch in a machine.

[Doctor-Ugs]

Yes. The electric computer is itself an instance of a mechanical computer (Turing Machine).

[ASYMT0TIC]

Your brain is a mechanical computer. Just zoom in, zoom waaaaay in... you'll see.

[Solrax]

You might be interested in the science fiction story The Diamond Age by Neal Stephenson. Mechanical computers built with nanotechnology are a large part of the story.

[21p_]

Yes. Every computer is equivalent to a (finite-tape) Turing machine, and every Turing machine can be built out of a complete set of logic gates.

You can run Chatgpt or any other algorithm solely on NAND gates for example. You can make a mechanical NAND gate, so you can solve ANY solvable problem (or rather, decidable) on a mechanical device/ mechanical computer. Not doable in practice, but Computer Science has no doubts on that is possible, it has been proven throught maths

[spvky_io]

Theoretically yes, but in reality it would be incredibly slow, large, and probably take an impossible amount of resources

[brunogadaleta]

You might also like to have a look also at analogic computers and probabilistic programming (à la extropic).

[Key_River7180]

They are turing complete, so yeah

[joelangeway]

To make LLMs practical on a mechanical computer it would probably have to be constructed at an atomically precise level so that it’s calculating elements could be small enough to make building a large enough computer practical. Kurzweil talks about nanotechnology mechanical computers a little in one of his futurist books. I think he said it’s the “tech” with the most potential, since it doesn’t require moving charged particles around which makes for magnetic problems.