This really needs a WebGPU port. Multigrid on a GPU is moderately easy.
> (c) Brandon Li, 2025. Ported to Javascript with the help of Paul Falstad.
[1] https://www.zachtronics.com/kohctpyktop-engineer-of-the-peop...
https://web.archive.org/web/20160305205215/http://www.zachtr...
Can this simulate this?:
"Synaptic and neural behaviours in a standard silicon transistor" (2025) https://www.nature.com/articles/s41586-025-08742-4 .. https://news.ycombinator.com/item?id=43506198
What about (graphene) superconductors though?
Note that my simulation is intended for educational purposes only, not scientific research.
- Brandon
What does the simulator say about signal delay and/or propagation in electronic circuits and their fields? How long does it take for a lightbulb to turn on after a switch is thrown, given the length of the circuit and the real distance between points in it?
(I learned this gap in our understanding of electron behavior from this experiment, which had never been done FWIU: "How Electricity Actually Works" (2022) https://www.youtube.com/watch?v=oI_X2cMHNe0 )
FWIW, additionally:
Hall Effect and Quantum Anomalous Hall Effect;
"Tunable superconductivity and Hall effect in a transition metal dichalcogenide" (2025) https://news.ycombinator.com/item?id=43347319
ScholarlyArticle: "Moiré-driven topological electronic crystals in twisted graphene" (2025) https://www.nature.com/articles/s41586-024-08239-6
NewsArticle: "Anomalous Hall crystal made from twisted graphene" (2025) https://physicsworld.com/a/anomalous-hall-crystal-made-from-...
From "Single-chip photonic deep neural network with forward-only training" https://news.ycombinator.com/item?id=42314581 :
"Fractional quantum anomalous Hall effect in multilayer graphene" (2024) https://www.nature.com/articles/s41586-023-07010-7
"Coherent interaction of a-few-electron quantum dot with a terahertz optical resonator" (2023) https://arxiv.org/abs/2204.10522 .. https://news.ycombinator.com/item?id=39365579
> "Room-temperature quantum coherence of entangled multiexcitons in a metal-organic framework" (2024) https://www.science.org/doi/10.1126/sciadv.adi3147
Electrons (and photons and phonons and other fields of particles) are more complex than that though.
The gap between the wires is about 1 micrometer, so light should take about 3 fs to propagate through. The simulation output approximately matches this prediction, and over the first few tens of femtoseconds the current increases, with a jump at around 70 fs due to the reflected wave. All of this is pretty much in line with the results of Veritasium's experiment.
Thanks for bringing it up. I might include this as another example in my sim.
These are cool _ wave propagation vids too; Nils Berglund wave visualizations: https://youtu.be/v0cZjOIfwos?si=07w2Wd4dPlGmNxHp
_: photon, fluid, standing transverse,, plasma
What about longitudinal waves in plasma, superconductors, and superfluids though? https://www.google.com/search?q=What+about+longitudinal+wave...
I suppose vorticity doesn't matter that much for classical electronic circuits
em3rgent0rdr•9mo ago
amelius•9mo ago
I also wonder why the simulator only allows to show E and D fields, and not H and B.
Steuard•9mo ago
Possibly related: there are options to "View B" and "View H" in the scalar dropdown, not in the vector one. That may be closely related to the fact that in two dimensions, the magnetic field has just a single component. Whether you describe is as a 2-form or a bivector, the magnetic field is an antisymmetric rank-2 tensor: an antisymmetric matrix. In 3D, that means 3 independent components, and there's a one-to-one mapping to vectors (more or less). But in 2D, an antisymmetric matrix has just one independent component. (And in 4D, it's got six: this is precisely the relativistic electromagnetic field tensor, that in 3D splits into an electric part and a magnetic part. My paper has more details.)
amelius•9mo ago
ajb•9mo ago
This is because it's actually an emergent property already in 2d space.
Consider a resistor shaped like a capital letter Z in 2d space, with ground at one end and 1V the other. (Assume also that the Z has a square aspect ratio). The potential along the bar in the middle will initially be equal, because all points on the bar are equidistant from our voltage sources (AKA charges) . But the potential will drop along the arms of the Z. So charge will move along the arms and accumulate at the corners, until there is also a voltage drop along the bar, and ohms law holds.
Steuard•9mo ago
Looking at the examples, it seems like you can make 1D and 2D strings/grids of resistors here in much the same way you would in a 3D model; you just can't make a 3D grid (or non-planar circuits). My general experience working with and teaching basic circuits is that it's rare that we consider current flow in a genuinely 3D medium: the vast majority of problem-solving examples approximate wires as simple 1D paths for charge to follow, and more careful treatments that talk about where charges accumulate to guide current flow around corners, etc. still almost always illustrate their points in 2D diagrams/examples.
So my impression is that this simulation is likely to give a pretty solid qualitative sense of how these systems work, despite its 2D framing.
stunningllama•9mo ago
- Brandon