[HN Gopher] Spintronics: Build Mechanical Circuits
___________________________________________________________________
Spintronics: Build Mechanical Circuits
Author : mcp_
Score : 220 points
Date : 2021-05-20 15:31 UTC (7 hours ago)
(HTM) web link (www.kickstarter.com)
(TXT) w3m dump (www.kickstarter.com)
| nemo1618 wrote:
| 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?
| carapace wrote:
| Mechanical multiplication is easy:
| https://en.wikipedia.org/wiki/Sliderule
|
| See more generally: https://en.wikipedia.org/wiki/Nomogram
| Laremere wrote:
| 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
| RandallBrown wrote:
| You should read Neal Stephenson's Diamond Age. It's in an
| alternate future where they use mechanical computers.
| pgboswell wrote:
| 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 wrote:
| See https://en.wikipedia.org/wiki/There%27s_Plenty_of_Room_at
| _th... and https://en.wikipedia.org/wiki/Engines_of_Creation
|
| TL;DR we're nowhere close to exploiting the full potential of
| nanoscale mechanical systems.
| mdaniel wrote:
| 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: ht
| tps://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 ...
| tlb wrote:
| Mechanical Turing machines can be small, such as:
| https://hackaday.com/2018/03/08/mechanical-wooden-turing-mac...
|
| They will take a long time to compute something like SHA2
| nynx wrote:
| 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.
| gene-h wrote:
| Rod logic will not be faster than electronic computers.
| According to Drexler's thesis, it's reasonable to expect
| "that RISC machines implemented with this technology base can
| achieve clock speeds of ~ 1 GHz, executing instructions at ~
| 1000 MIPS."
|
| This is because the speed of sound, which limits how fast
| mechanical signals can propagate, is much lower than the
| speed of light.
|
| The main advantages of rod logic is that its compact and
| power efficient. The aforementioned CPU would consume ~100
| nW.
|
| Really the reason why Drexler analyzed rod logic in the first
| place is that it was easy to analyze and something that his
| proposed assemblers could plausibly construct, better
| alternatives for fast computing may exist.
|
| [0]https://dspace.mit.edu/handle/1721.1/27999
| nynx wrote:
| This is true, but it's important to consider that you could
| squeeze several billion of these processors into the space
| taken up by current CPUs.
| pgboswell wrote:
| This is very interesting. Why would they be faster?
| zardo wrote:
| 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.
| nxpnsv wrote:
| I guess you can do it with pen and paper and patience...
| gene-h wrote:
| I wonder if you could make a torque amplifier[0] with the
| transistors? A torque amplifier is a mechanical device which
| takes in a shaft rotation and power outputting the same rotation
| angle except with higher torque.
|
| This was an important component in mechanical computers to
| amplify outputs disc integrators which outputted shaft rotations
| at low torque.
|
| It might be a fun device to make because you could use this to
| make part of a steampunk exoskeleton where the user can turn a
| small arm to move a much large arm. Because torque is amplified
| it will be easier to move the heavier arm.
|
| [0]https://en.wikipedia.org/wiki/Torque_amplifier
| quanto wrote:
| This reminds me of when I was taking an advanced circuit design
| class. The analog circuit in question had many moving parts, and
| I just didn't have the intuition. The teaching fellow at the time
| thought it would help to visualize a mechanical analog (ha!) of
| the circuit and drew for me a complex mechanical diagram. It was
| so complex that I found it more intuitive to just study the
| electrical circuit directly.
|
| After years of working with electrical circuits, I now often find
| it easier to translate a mechanical system in question to an
| analogous electrical system and analyze it. In fact this is where
| the phrase "analog electronics" comes from: It is an analogue of
| a real world (often mechanical) system. At the end of the day,
| these are all (mostly second order) differential equations.
| hintymad wrote:
| This is amazing and looks fun! I immediately paid to support the
| project, so I can play the toy later.
|
| That said, I wonder if it will really make learning circuit
| easier. I have a hard time imagining that kids would give up
| learning circuit just because they couldn't get the abstractions.
| The biggest obstacle to learning, per my limited observation of
| course, is always lack of innate curiosity or sometimes talent.
| Those who get discouraged by the so-called difficult abstraction
| probably do not need to learn circuitry in the first place.
|
| By the way, I find the promotional video interesting. There are a
| few frames that talk about how a kid had to resort to maths and
| what not to understand circuits, and videos showed kids checking
| out oscilloscopes, square waves, some complex circuits that
| looked like Y-delta transforms, and voltage-ampere curves (or
| something like that). I mean, if a kid would look into those
| things, why would we worry that the kid can't learn circuit? And
| since when looking into math is a bad thing?
|
| Boswell's idea seems aligned with the movement of progressive
| math education in the US, which advocates that there's gotta be
| an easy and intuitive way to motivate and enable _every_ kid to
| discover and grasp math concepts. I think it 's a noble goal. I'm
| just not sure if everyone is born with the drive or aptitude.
| jerf wrote:
| I am positively agog. This is amazing.
|
| I would suggest to pgboswell that it may be interesting to reach
| out to a few local professors who teach introductory circuits at
| some nearby universit(y/ies) and do an in-person demo of the
| components. You may find you have a significant educational
| market you could tap into. I could well believe there's a lot of
| people who just never quite make it over the abstraction gap to
| understand circuits who would be able to follow them if they
| could physically interact with a mechanical circuit running at
| human orders of magnitude.
| ocdtrekkie wrote:
| This reminds me of something I read about the other day (probably
| also from HN), a mechanical exploratory rover:
| https://www.jpl.nasa.gov/news/a-clockwork-rover-for-venus
|
| This really helps visualize how one might make "computation" with
| mechanical parts possible!
| dpeck wrote:
| This is from the same person (team?) that made Turing Tumble,
| which has been great fun to do with my 8 year old. The puzzles
| are a lot of fun and gives a nice intuitive feel for "circuits"
| and basic mechanical logic ( ands, ors, counters, etc)
| computation.
|
| Highly recommended if you've got a kid in your life who likes
| figuring out and building things. https://www.turingtumble.com/
| krasin wrote:
| Yes, this is from the same person. Turing Tumble is almost
| amazing. Unfortunately, gears and balls used there are not
| reliable enough and more complex circuits have abysmal
| reproducibility (~50%).
|
| I tried it with my kids and they were _very_ excited up until
| this unreliability killed all the fun. I wish Turing Tumble had
| a premium version with a better determinism.
| coupdejarnac wrote:
| Sounds like a pretty authentic engineering experience then.
| krasin wrote:
| Yes. But kids like to be exposed to the joy of engineering
| first. It's otherwise hard for them to justify the pain
| that's required to get to the joy of success.
| Animats wrote:
| Oh, that's precious. I hope they ship this, and that the
| components aren't too expensive. They look expensive.
| sumthinprofound wrote:
| Wish I had this as a kid but still excited to own it once it's
| released!
| [deleted]
| lxe wrote:
| Mechanical inductors, capacitors, and even transistors? That's
| and incredible feat. Developing intuition about how to put the
| components together to build something like an oscillator or a
| flip flop is a must for electronics enthusiasts.
| syoc wrote:
| This looks really cool. Would be interested myself even if I am
| probably outside the intended age bracket. I can't help think
| that the parts look really flimsy based on the videos. They look
| kind of 3d printed and the plastic seems cheap. Hope that's not
| the case.
| adeledeweylopez wrote:
| That's probably because they are 3D printed prototypes. He says
| in the link that they're working on creating the molds for
| injection molding.
| lapetitejort wrote:
| I'm amazed at all the ways we can simulate circuits. The classic
| is pipes and water, however you can also use car traffic, heat
| transfer, and now gears!
|
| My question is can you simulate how resistors behave in series
| versus parallel? How about capacitors?
| [deleted]
| gugagore wrote:
| I am glad to see that they are using LEGO Technic chains
| (https://www.bricklink.com/v2/catalog/catalogitem.page?P=3711) ,
| and therefore the gear pitches are LEGO compatible (at least with
| the non-bevel gears, but the traditional spur gears). I am
| excited about the potential of interacting with existing Technic
| parts!
| Xunxi wrote:
| I personally find it quite refreshing to see accessible hardware
| projects showing up once again. The ensuing discussions are full
| of nuggets and somewhat esoteric recommendations that always
| draws me down the rabbit hole where I end up discovering a lot of
| things I wish I could visualize when I was much younger.
|
| Is a pleasurable learning experience.
|
| NB:This post and OpenFlexure
| ajarmst wrote:
| I was a backer for their previous project: Turing Tumble. It was
| a very positive experience, with timely informative updates and
| ultimately a high quality product.
| spoonjim wrote:
| Turing Tumble is so great.
| spoonjim wrote:
| I was going to say "this better be as good as Turing Tumble!" Now
| I see it's by the same guy. BUY
| pgboswell wrote:
| Hey cool! I made this. It's fun to see it here on Hacker News!
| jkingsman wrote:
| I took four years of engineering in university and work in
| software now, and one gif on your page made inductors click
| intuitively for me in a way that so many courses did not --
| thank you!
| pgboswell wrote:
| Ha ha! Thanks so much!
| GistNoesis wrote:
| I'm eager to see what a memristor would look like.
| mcp_ wrote:
| I loved playing your last project Turing Tumble with my
| daughter. So I am really looking forward to your new project.
| pgboswell wrote:
| Thanks so much for the kind words.
| rkagerer wrote:
| I wish there were a pledge level where I'd buy one kit for me,
| and anonymously gift one to some kid in another part of the
| world who wants one but can't afford it (kind of like OLPC
| did).
| [deleted]
| Judgmentality wrote:
| I'm only just hearing about this now but I love the idea and
| wish you great success.
| d--b wrote:
| This is great! I didnt even know there were mechanical analogs to
| electronic parts. This is going to make electronic teaching an
| awful lot mote intuitive!
| c-smile wrote:
| There are also such things as "pneumonics" and "fluidics" :
| https://en.wikipedia.org/wiki/Fluidics
|
| These are used, for example, in avia and rocket engines - in
| first or independent contours of their control systems. Such
| logic devices are very reliable, relatively simple and can work
| at extreme temperatures.
| gugagore wrote:
| There are two possible mechanical analogies to electrical
| circuits (https://en.wikipedia.org/wiki/Mechanical%E2%80%93electr
| ical_...). In domains (electrical, acoustic, thermal, mechanical,
| ...) there are two kinds of quantities, sometimes called "across"
| (voltage, temperature difference, ...) and "through" (current,
| heat, ...).
|
| My first guess was that the analogy here appears to be velocity
| is voltage and force is current, but I think I have that
| backwards. The battery, which I was taking to be a ideally a
| voltage source without internal resistance, appears to be a
| constant-torque mechanical device. Connecting it in series to
| different resistances means it spins at different speeds
| (different current is drawn).
|
| But the battery will also spin if it's not connected to
| anything... so I'm struggling to keep the analogy straight while
| thinking about how these parts behave ideally and non-ideally.
|
| Looking at the ammeter, it's definitely velocity = current.
|
| Edit: and finally direct evidence
|
| > But the most practical place for [ground] to be is anywhere
| there is zero force (i.e., voltage) on the chain.
| prpl wrote:
| Sort of unfortunate to reuse this term which has been a field of
| study in solid state physics for a very long time:
|
| https://en.m.wikipedia.org/wiki/Spintronics
| lapetitejort wrote:
| The main difference is that spinning gears makes sense, whereas
| spinning electrons do not!
|
| (I kid of course. Spin in physics relates to inherent angular
| momentum. If you wonder why that exists, you may also want to
| wonder why mass exists.)
| whatshisface wrote:
| Intrinsic angular momentum is weirder than intrinsic mass
| because you can take it out and put it back in - although for
| most particles you're not allowed to have zero. But you are
| allowed to take 1 from an electron to go from 1/2 to -1/2. If
| that is not enough, you can go back from -1/2 to 1/2 by
| changing your basis vectors. ;)
| jeffwass wrote:
| Further - paired electrons can collectively form the spin-
| zero singlet state, or spin-one triplet state. In either
| case the two electrons, which are fermions independently,
| together act like a boson (eg, Cooper Pairs in a
| Superconductor).
|
| Addition of quantum angular momentum is _really weird_.
| jeffwass wrote:
| Agreed, it's an unfortunate namespace collision. Spintronics is
| a really cool area of physics, with decades of research.
|
| Electrons have spin. Although 'classical semiconductors'
| exploit the electron's spin via the Fermi-Dirac distribution in
| transistors, the actual sign / direction of the 'spin' is
| ignored in everyday electronics. Making use of this available
| spin degree-of-freedom opens up a whole wealth of new
| possibilities.
|
| Spintronics has already revolutionized certain industries (eg,
| GMR in magnetic hard drives), and there are further open areas
| of research (eg, spin as qubit basis states in quantum
| computers).
| mumblemumble wrote:
| But then, all puns are unfortunate. It's kind of their thing.
___________________________________________________________________
(page generated 2021-05-20 23:00 UTC)