Microprocessors Running on Air?
erik-engheim.medium.com
erik-engheim.medium.com
>The pipes are laid out horizontally, like a rank of organ pipes that has been knocked flat. Stuck into one end of each pipe is a little paper speaker ripped from an old radio.
>“The speaker plays a signal—a note—that resonates in the pipe, and creates a standing wave,” Waterhouse says. “That means that in some parts of the pipe, the air pressure is low, and in other parts it is high.” He is backing down the length of one of the pipes, making chopping motions with his hand. “These U-tubes are full of mercury.” He points to one of several U-shaped glass tubes that are plumbed into the bottom of the long pipe.
>[...]
>“If the air pressure in the organ pipe is high, it pushes the mercury down a little bit. If it’s low, it sucks the mercury up. I put an electrical contact into each U-tube—just a couple of wires separated by an air gap. If those wires are high and dry (like because high air pressure in the organ pipe is shoving the mercury down away from them), no current flows. But if they are immersed in the mercury (because low air pressure in the organ pipe is sucking the mercury up to cover them), then current flows between them, because mercury conducts electricity! So the U-tubes produce a set of binary digits that is like a picture of the standing wave—a graph of the harmonics that make up the musical note that is being played on the speaker. We feed that vector back to the oscillator circuit that is driving the speaker, so that the vector of bits keeps refreshing itself forever, unless the machine decides to write a new pattern of bits into it.”
Mechanical computing in general is fascinating. People also used to use precisely-machined drums and cams to perform complex realtime calculations.
All of which were likely to change where you were about to demonstrate your new mainframe to a delegation of important people! :-) IIRC it was even named "the general syndrome" in some places.
Delay line memory relies on the speed of sound through a medium. You put a signal in at one end, and it propagates “slowly” to the other, where you receive the signal, and immediately replay it at the start. Creating a kind of never ending echo.
What’s described above relies on a standing wave in a tube, with sensors along the length of the tube to detect nodes and anti-nodes. Then encoding data into that by changing the signal input to change the locations of the nodes and anti-nodes.
I don’t think such a system would actually work, because your stuck using only the harmonics of your tube as possible states, and there’s gonna be a pretty limited number that you could realistically produce.
Standing wave memory would mostly defeat the point of having memory, since you'd need to address every single antinode individually. You might as well just have a bunch of latches. The real point of delay lines, shift registers, or core memory is to reduce the address space: you store bits in a way that is slower but simpler to access, which means you can store more things. Mercury standing waves would not make it any easier to store bits, so there's no advantage.
Still, you could make a device like that. Only 2/3rds of the tube can store memory- the rest is a quarter-wave transformer, which basically makes the tube act as if it was open at both ends. You can construct arbitrary patterns with fourier decompositions: https://en.wikipedia.org/wiki/Periodic_summation
This is a common theme in sci-fi. Authors tend to know enough to make something sound plausible; but it's pretty rare for their inventions to pass the sniff test. I'd say "they're not writing patents, after all" but Salvatore Pais took that away from me:
https://www.thedrive.com/the-war-zone/31798/the-secretive-in...
I've also seen the liquid model of the economy.
I have a copy of Svoboda on 3 bar linkage computing in the MIT radiation labs series, published in the post war period. All the examples look to be flight and ballistics related, I guess these kinds of things were used for bomb and gun aiming, and radar.
I've enjoyed making microfluidics in the past, and hope to make more in the future, but 'hey do it in parallel' isn't useful, its obvious.
It rather briefly covers the main basics questions one might have after hearing first being exposed to this idea.
What even is it? Computation. With fluid. Is it possible? Water jet example. Okay but seriously, is it practically possible? Parallelism, so sure. Is it useful? Venus.
I don't see how the main point of this blog post could possibly be parallelism. It's mentioned, but in about as much detail as all of the other topics I listed above.
The whole thing is also so simplistic that I don't see how it could possibly be targeted at people with actual knowledge - never mind experience - in the field.
What is it? Does it work? Does it actually work in practice? What do you do with it?
For somebody first exposed to the topic, that's kind of the basic starting point. The post kind of directly went from one answer to the next. As I was reading it the post felt pretty natural. But if you already know all that and are instead reading for more detailed knowledge, yeah I can see why that might seem particularly erratic. It was probably kind of like reading a Q&A without any of the Qs.
Quoting Scott:
> It’s important to realize that the idea of solving NP-complete problems in polynomial time using an analog device is far from new: computer scientists discussed such ideas extensively in the 1960s and 1970s. Indeed, the whole point of my NP-complete Problems and Physical Reality paper was to survey the history of such attempts, and (hopefully!) to serve as a prophylactic against people making more such attempts without understanding the history. For computer scientists ultimately came to realize that all proposals along these lines simply “smuggle the exponentiality” somewhere that isn’t being explicitly considered, exactly like all proposals for perpetual-motion machines smuggle the entropy increase somewhere that isn’t being explicitly considered.
With the exception of Quantum Computers, but in limited cases, quoting Scott:
> (Incidentally, quantum computing is interesting precisely because, out of all “post-Extended-Church-Turing” computing proposals, it’s the only one for which we can’t articulate a clear physical reason why it won’t scale, analogous to the reasons given above for memcomputing. With quantum computing the tables are turned, with the skeptics forced to handwave about present-day practicalities, while the proponents wield the sharp steel of accepted physical law. But as readers of this blog well know, quantum computing doesn’t seem to promise the polynomial-time solution of NP-complete problems, only of more specialized problems.)
https://www.scottaaronson.com/blog/?p=2212
From listening to Scott for many years, I don't have the expertise in this area to say it definitively, but most likely, your cool new analog computing idea isn't going to break the RSA anytime soon ;)
Further reading: https://www.scottaaronson.com/democritus/lec14.html
I couldn't open it and asks for a login account with Medium.
This caught my eye. It seems entirely too simplistic to claim the brain has a "hz" value/directly compare to traditional computing, doing some research, but anyone more knowledgeable on this?
I’d say that they probably took the simplest task possible and see how fast the human brain could do that and ended up with 30Hz. Seems like a very silly thing to me.
The human brain obviously works in parallel but that doesn't mean that it doesn't have something akin to a clock frequency. There is a limit to how quickly signals can propagate through the brain.
https://en.wikipedia.org/wiki/Neuroscience_of_rhythm
https://patrickjuli.us/2016/04/06/what-is-the-processing-pow...
It is based on the fastest neurologic rhythms in the human brain.
Then in large server farms you'd basically need specialized HVAC engineers to design them, and admins with earplugs and goggles trained on the safety protocols of walking through 40mph wind tunnels through rows of server racks. "Server crash" could refer to an accident navigating the wind currents.
My next thought was, what about random mechanical malfunctions? We face this with electronic devices too: electromagnetic interference, cosmic rays, etc. It's all about understanding the operating conditions where the device will be used and designing accordingly. It seems like most of the techniques we have learned in the electronics world have an analogous approach in mechanical computing.
It's fun to think about the possibilities, and will be interesting to watch how old tech like this could be used in the future.
https://hackaday.com/2019/04/23/making-microfluidics-simpler...
Fluidics can run amplifiers for acoustic signals, which you can use for transmission.
Seeing can be done like bats. Article gets into the details.
If we could just find a problem for the fluidics solution... Kinda like lasers in 1960, it works so now what do we do with it?
The other interesting fluidics note is its been popular in hard sci fi for decades (well, for certain very small values of popular). The problem with fluidics is you need a pretty big digital computer to optimize the fluid mechanics and fancy digital computers to run the CNC machines to carve out the 3-d shapes. But if you could be VERY patient to do the calculations by hand and find a way to make the processors using 2-d photolithography maybe space aliens would have a fluidic technology.
Another interesting note is this scales by size and speed of sound in liquid so its always going to be slower than photonics or electronics. But, the computational power to do "stuff" seems to scale on a power law so the invisible hand of cheapness means your smart thermostat for a hydronic hot water heating system would inevitably be fluidic in nature given an infinite number of years of market pressure. Yeah, a "big easy to mess with by hand" system is as slow as a pocket calculator, but we sold the world a heck of a lot of pocket calculators over the decades and if you shrink the dimensions by a million and increase pressure modestly and you could run a fluidic cell phone, perhaps.
However, if you do the math it appears that fluidic amplifiers with dimensions that do not require semiconductor processing to make using a working fluid of helium should have flat gain to about 26 KHz, which is in the ultrasonic range. What really makes this work is the fact that helium becomes less viscous as it gets much hotter.
In fact power requirements for fluidic amplifiers may be about the same as their electronic counterparts(~0.2 mW per amplifier). In addition, laminar fluidic amplifiers have very low internal noise, meaning we should be able to amplify the fairly weak sonar return signals. A simple sonar sensor which reports back range should be possible, but a more interesting possibility is using acoustic metamaterials to do 'image recognition' to steer the rover away from obstacles.
A couple problems are how to couple sound from the fluidic circuits to Venus' atmosphere and keeping the helium contained. Having the entire circuit encased in metal and using metal would ensure that the leakage rate is insignificant. The issue is that making a reliable metal bellows pump could end up being a boondoggle. NASA tried to make an RTG that used a stirling engine rather than a Seebeck generator, but it stopped working reliably within a month or so, which may have been due to fatigue in the metal bellows. Another is it's difficult to determine sonar system performance due to the difficulty of calculating return strength
Edit: I wish I could edit the grammar and syntax mistakes.
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