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 Mar 17 accepted Is it possible to increase refractive index at lower densities? Mar 14 awarded Popular Question Feb 18 comment Historical costs of nuclear magnetic resonance experiments @dmckee I think it belongs in history of science (a lot of historical research concerns the price of things) Feb 18 comment Historical costs of nuclear magnetic resonance experiments @CarlWitthoft I'd like to get my hands on some data. Anyone can predict that they would have got cheaper, but I would like to know empirically, and by how much. Feb 18 comment Historical costs of nuclear magnetic resonance experiments @PeterDiehr Sure. I was kind of hoping that, along the lines of (b), there might be some MR experts who would know where to look, or how to make the question easier to answer. Expert input would make answering the question much easier. For example, they might have had to justify the running costs to their department, or, perhaps they've read around the topic enough to know where some esoterically conceived but relevant data is. Feb 18 comment Historical costs of nuclear magnetic resonance experiments @AccidentalFourierTransform I didn't know that existed, that does sound more appropriate. Feb 18 asked Historical costs of nuclear magnetic resonance experiments Sep 28 awarded Notable Question Aug 10 accepted Calculating the resistance of a 3D shape between two points Aug 10 comment Calculating the resistance of a 3D shape between two points yes, this is what I was looking for. I'd figured it talking with RossMillikan below, but it never made it to a proper answer. Jun 30 awarded Curious Jun 29 comment Rules of thumb for estimating visual angles Luckily, it's dark ;) Jun 29 comment Rules of thumb for estimating visual angles That's a creative suggestion. Not sure I can execute it (and then move my arms to the right position) even remotely accurately. One can rule out the 46 degree halo with only one halving, or see if the diameter is 92 without any halving at all. Jun 29 asked Rules of thumb for estimating visual angles Jun 21 awarded Yearling Jun 21 comment Calculating the resistance of a 3D shape between two points My model above has about 10,000 nodes. It took about 100,000 iterations to converge. I hope I've done it right, some reverse engineering implies what I've been doing is solving Laplace's equation $\nabla^2 \phi = 0$ with boundary conditions $(\hat{n} \cdot \nabla) \phi = 0$ for non-contacts and $\phi = const$ for the contacts. This seems very plausible to me now. You've been very helpful, thanks. Jun 21 comment Calculating the resistance of a 3D shape between two points OK, I'm convinced, and I have a much better understanding now, thanks. See question for some plots. Jun 21 revised Calculating the resistance of a 3D shape between two points added some simulations based on an answer below Jun 21 comment Calculating the resistance of a 3D shape between two points I've just about coded a basic relaxation procedure in 2D. I'll put some results in the OP when I've got some. Jun 20 comment Calculating the resistance of a 3D shape between two points I'm not 100% convinced, but you've persuaded me to code something up and see. Assuming this is correct though, doesn't it suggest an equation expressed in terms of the minimisation of some function?