There's a minimum size at which such mechanisms will work, and it's bigger than transistors. This won't scale down to single atoms, according to chemists.
[1] http://www.nanoindustries.com/nanojbl/NanoConProc/nanocon2.h...
Merkle developed several of his families of mechanical logic, including this one, in order to answer some criticisms of Drexler's earliest mechanical nanotechnology proposals. Specifically:
1. Chemists were concerned that rod logic knobs touching each other would form chemical bonds and remain stuck together, rather than disengaging for the next clock cycle. (Macroscopic metal parts usually don't work this way, though "cold welding" is a thing, especially in space.) So this proposal‚ like some earlier ones like Merkle's buckling-spring logic, avoids any contact between unconnected parts of the mechanism, whether sliding or coming into and out of contact.
2. Someone calculated the power density of one of Drexler's early proposals and found that it exceeded the power density of high explosives during detonation, which obviously poses significant challenges for mechanism durability. You could just run them many orders of magnitude slower, but Merkle tackled the issue instead by designing reversible logic families which can dissipate arbitrarily little power per logic operation, only dissipating energy to erase stored bits.
So, there's nothing preventing this kind of mechanism from scaling down to single atoms, and we already have working mechanisms like the atomic force microscope which demonstrate that even intermittent single-atom contact can work mechanically in just the way you'd expect it to from your macroscopic intuition. Moreover, the de Broglie wavelength of a baryon is enormously shorter than the de Broglie wavelength of an electron, so in fact mechanical logic (which works by moving around baryons) can scale down further than electronic logic, which is already running into Heisenberg problems with current semiconductor fabrication technology.
Also, by the way, thanks to the work for which Boyer and Walker got part of the 01997 Nobel Prize in Chemistry, we probably know how ATP synthase works now, and it seems to work in a fairly similar way: https://www.youtube.com/watch?v=kXpzp4RDGJI
The rod & shaft designs are passivated. This kind of reaction wouldn't happen unless you drove the system to way higher energies than were ever considered.
> Someone calculated the power density of one of Drexler's early proposals and found that it exceeded the power density of high explosives during detonation
I think this is a (persistent) misunderstanding. His original work involved rods moving at mere millimeters per second. There are a number of reasons for this, of which heat dissipation is one. However all the molecular mechanics simulations done operate at close to the speed of sound in the material, simply because they would otherwise be incalculable. There is sadly a maximum step size for MD simulations that is orders of magnitude lower than what you would need to run at realistic speeds.
> You could just run them many orders of magnitude slower, but Merkle tackled the issue instead by designing reversible logic families which can dissipate arbitrarily little power per logic operation, only dissipating energy to erase stored bits.
The rod logic stuff is supposed to be reversible too. Turns out it isn't though. But it could be close enough if operated at very low speeds or very low temperatures.
The rod logic stuff is WAY smaller than the rotational logic gates in TFA. For some applications that matters, a lot.
If you are going to go for the scale of these rotational systems, you might as well go electronic.
(Also, passivation doesn't eliminate van der Waals bonds.)
I think I must be missing something here, I thought this was working with atoms. Are you saying that someday mechanical logic could be made to work inside the nucleus? Seems like you might be limited to ~200 nucleons per atom, and then you'd have to transmit whatever data you computed outside the nucleus to the nucleus in the next atom over? Or are we talking about converting neutron stars into computing devices? Do you have a good source for further reading?
We routinely force electrons to tunnel through about ten nanometers of silicon dioxide to write to Flash memory (Fowler–Nordheim tunneling) using only on the order of 10–20 volts. That's about 60 atoms' worth of glass, and the position of each of those atoms is nailed down to only a tiny fraction of its bond length. So you can see that the positional uncertainty of the electrons is three or four orders of magnitude larger than the positional uncertainty of the atomic nuclei.
https://en.wikipedia.org/wiki/Chemical_clock
(This version can be done at home with halides imho: https://en.wikipedia.org/wiki/Iodine_clock_reaction)
To your question: I suppose all you need is for the halide moieties (Br) in your gates to also couple to the halide ions (Br clock?). The experiment you link was conducted at 7K for the benefit of being able to observe it with STM?
The experiment was conducted at 7K so the molecule would stick to the metal instead of shaking around randomly like a punk in a mosh pit and then flying off into space.
>The experiment was conducted at 7K so the molecule
Br is good at sticking to Ag so I suspect the 7K is mainly (besides issues connected to their AFM^W STM setup) because the Euro dudes love ORNL's cryo engineering :)
Yeah that's a reason people prefer AFM (but then they won't be able to do manipulation)?
[Br- is a "good leaving group", not so much at 7K maybe. You are also right in that, above all, they don't want their molecule sticking (irreversibly) to the (tungsten) tip ]
https://wornandwound.com/no-escapement-an-overview-of-obtain...
https://monochrome-watches.com/in-depth-the-future-of-silico...
https://www.chrono24.com/magazine/innovative-escapements-fro... (warning, GDPR mugging)
https://www.azom.com/article.aspx?ArticleID=21921
https://www.europastar.com/the-watch-files/those-who-innovat...
Transistors can do more than on and off, there is also the linear region of operation where the gate voltage allows a proportional current to flow.
So you would be constructing an analog computer. Perhaps in operation it would resemble a meat computer (brain) a little more, as the activation potential of a neuron is some analog signal from another neuron. (I think? Because a weak activation might trigger half the outputs of a neuron, and a strong activation might trigger all outputs)
I don’t think we know how to construct such a computer, or how it would perform set computations. Like the weights in the neural net become something like capacitance at the gates of transistors. Computation is I suppose just inference, or thinking?
Maybe with the help of LLM tools we will be able to design such things. So far as I know there is nothing like an analog FPGA where you program the weights instead of whatever you do to an FPGA… making or breaking connections and telling LUTs their identity
[1] https://www.kip.uni-heidelberg.de/Veroeffentlichungen/detail...
Anyway, if this kind of computer was so great maybe we should just encourage people to employ the human reproduction system to make more.
There’s a certain irony of critics of current AI. Yes, these systems lack certain capabilities that humans possess, it’s true! Maybe we should make sure we keep it that way?
It is already common practice to deliberately inject noise into the network (dropout) at rates up to 50% in order to prevent overfitting.
If you don't mind my asking, how much does the role of mutual information in linking logical and thermodynamic reversibility depend on considering quantum systems? I.e. does your footnote 37, which discusses independent systems vs "subsystems of correlated systems" hold for classical systems as well?
Edit: I love that other people are thinking about this around now
But ideally once manufactured, a given LLM "model" will be a single solid crystal, such that shining an array of beams into it, will come out the other end of this complex crystal as an "inference" result. This will mean an LLM that consumes ZERO ENERGY, and made of glass will also basically last forever too.
We already have Optical Chips but they don't quite do what I'm saying. What I'm saying is essentially an "Analog LLM" where all the vector adds, mults, and tanh functions are done by the light interactions. It seems possible, but I think it's doable.I think there should theoretically be a "lens shape" that does an activation function, for example. Even if we have to do the multiplications by conventional chips, in a hybrid "silicon-wave system" such an "Analog Optical LLM" would still have huge performance and energy savings, and millions of times faster than today's tech.
And being based on light, could utilize quantum effects so that the whole thing can become a Quantum Computer as well. We could use effects like polarization and photon spin perhaps to even have 100s of inferences happening simultaneously thru a given apparatus, as long as wavelengths are different enough to not interact.
Another way of looking at it: there are 4 states going in (0 or 1 on 2 pushers) but there are only 2 states of the 'memory' contraption, so you lose a bit on every iteration (like classical Boolean circuits)
Wow! What an absurd claim!
I checked the Wikipedia page and I think you actually meant 10^-21 J :)
P.S. I once calculated the mass of the sun as 0.7kg and got 9/10 points on the questions.
> The Technology Behind Remote Mind Reading
> The technology can be broken into multiple parts: the ability to read brainwaves remotely; the ability to decode brainwaves; the ability to beam back signals to the brain to influence it; the ability to apply this from a long distance; a mechanism for automation (to be able to apply it to a large number of victims); and an infrastructure for population-scale deployment.
> Believe it or not, every single one of those exists, and I will provide well-founded explanations in tangible details.
This doesn't seem to be related to reversible mechanical computing; rather, it seems to be a classic schizophrenic delusion. The evidence presented is a rather implausible patent from 01974 and a poster in all capital letters on "psycho-electronic weapon effects".
Presumably at some point this kind of thing will become possible, but no evidence is presented here showing that it has become possible already, and from what I know of the relevant fields, I don't see a way it would be possible today. It certainly wasn't possible in 01974 when the cited patent was published. The inventor was engaging in wishful, or perhaps schizophrenic, thinking.
By contrast, as a delusion, this belief has been a well-known symptom of schizophrenia since at least 01919: https://en.wikipedia.org/wiki/Thought_broadcasting https://archive.org/details/dementiapraecoxp00kraeiala/page/...
> But it is quite specially peculiar to dementia praecox that the patients' own thoughts appear to them to be spoken aloud. In the most varied expressions we hear the complaint of the patients constantly repeated that their thoughts can be perceived. They are said loud out [sic], sometimes beforehand, sometimes afterwards; it is "double speech," the "voice trial," "track-oratory," the "apparatus for reading thoughts," the "memorandum." A patient heard her thoughts sounding out of noises. In consequence of this everything is made public. What the patients think is known in their own homes and is proclaimed to everyone, so that their thoughts are common property. "I have the feeling, as if some one beside me said out loud what I think," said a patient. "As soon as the thought is in my head, they know it too," explained another. "When I think anything I hear it immediately," said a third. People look into the brain of the patient, his "head is revealed." When he reads the newspapers, others hear it, so that he cannot think alone any longer. "We can read more quickly than you," the voices called out to a patient. "Everyone can read my thoughts, I can't do that," complained a patient. Another said, "A person can have his thoughts traced by another, so that people can learn everything." A patient himself had "to whistle" his secrets "through his nose."
So, if you find yourself suspecting that there's a vast secret conspiracy to remotely read your mind, try to remember that that's a common delusion that literally millions of people have had, and most of them had it decades ago before there was any way it was possible, and it probably still isn't possible. If it were possible, there are a lot of more prosocial things that people would use it for: lie detector tests in job interviews and lawsuits, for example, or matchmaking services.
Sometimes combating delusions with reason doesn't work. Delusions can be extremely compelling! But sometimes it does.
> The patients frequently connect them [their strange experiences of hearing voices and feeling that others can read their thoughts] with malevolent people by whom they are "watched through the telephone," or connected up by wireless telegraphy or by Tesla currents. Their thoughts are conveyed by a machine, there is a "mechanical arrangement," "a sort of little conveyance," telepathy. A patient said, "I don't know the man who suggests that to me." Another supposed that it might perhaps be done for scientific purposes by a professor. A third explained, "I am perfectly sane and feel myself treated as a lunatic, while hallucinations are "brought to me by magnetism and electricity."
If you start with blank tape then it isn't really reversible computing, you're just doing erasure up front.
Consider the case, for example, of cracking an encryption key; each time you try an incorrect key, you reverse the whole computation. It's only when you hit on the right key that you store a 1 bit indicating success and a copy of the cracked key; then you reverse the last encryption attempt, leaving only the key. Maybe you've done 2¹²⁸ trial encryptions, each requiring 2¹³ bit operations, for a total of 2¹⁴¹ bit operations of reversible computation, but you only need to store 2⁷ bits to get the benefit, a savings of 2¹³⁵×.
Most practical computations don't enjoy quite such a staggering reduction in thermodynamic entropy from reversible computation, but a few orders of magnitude is commonplace.
It sounds like you could benefit from reading an introduction to the field. Though I may be biased, I can recommend Michael Frank's introduction from 20 years ago: https://web1.eng.famu.fsu.edu/~mpf/ip1-Frank.pdf
A more complete resource for finding my work count be found at https://revcomp.info.
I didn't realize you'd left Sandia! I hope everything is going well.