#computational physics

[charyou-tree]

I'm doing a periodic maintenance task for work, where I have to rebuild the container environment that our materials science computations get run in to update the versions of some software that we use, and I'm struck by just how much scientific knowledge is packed into this singularity image file that represents the container.

It takes like an hour to compile on modern hardware, from an Ubuntu (ha! the built in spell check in Ubuntu insists on capitalizing itself) base image with dozens of computational materials science simulation packages and supporting dependencies. These all have to be downloaded, compiled, linked, and installed in such a way that they can mutually interface, and take data and return results in the formats we use.

Once the whole thing is built, the final image is something like a gigabyte in size--5x that if we also install CUDA. I know that 1 Gb doesn't sound like that much data these days, some internet connections can download that in less than a second, but think about it:

This isn't a move or an image or a song. This archive contains almost no actual data. That gigabyte of space is pretty much entirely code instead; much of it compiled, executable code at that.

A gigabyte of materials science simulation Code, a billion characters worth of instructions, specifying the very best established practices for modeling the behavior of materials at the atomic level.

I know the digital age is old news, but I can't get over that level of cumulative effort. It represents tens of thousands of person-months of effort collectively, but I'm just sitting here watching my computer assemble it from a recipe that's short enough for me to read and sensibly edit, and distill that down into a finely-tuned piece of precision apparatus that fits on a flash drive.

And that isn't even the important part of our research! That's just all the shit we need installed on the system as background dependencies to be able to run our custom simulation code on top of that! Its so complex that at this point, its easier to run an entire (limited) virtual machine with our stuff installed in it than to try and convince every supercomputer cluster we work with to install every package separately and keep up with updates.

In case you're wondering what a day in the life of a computational materials physicist looks like: trying to do upgrades on incredibly complex machinery that you cannot touch or see. At least this time it doesn't also have to stay running while I do it...

[astrocatfizziks]

Love this library :)

pip install smplotlib

[maxwells-daemon]

nothing like developing a hyperfixation when I should be doing so many other things

[teledyn]

Could the Universe be a giant quantum computer?

“I think if he had had a more conventional education, if he’d come up through the ranks and had taken the standard physics courses and so on, maybe he would have done less interesting work.”

[aromanrom]

Quantum Computing Simulator

Introduction There is a ‘new’ repository on GitHub1. It’s not that new, I think I started it in September 2022, but I didn’t add any description on it here. So, here it is now: A quantum computation project. It’s a quantum computing simulator together with many algorithms as examples and tests. It started first as a very simple simulator, one that simply followed the math, with matrices, tensor…

[andranikfakirian]

Project "CompMath.AstrophysicsODEs": Early Projects, Part 2

Let's continue the series of Early Projects. The next one was from the sphere of analytical mechanics. The task was to simulate the rotational motion of bodies using quaternions. Quaternions make it possible to describe such motions quite succinctly in formulas. Special attention should be paid to modeling the Dzhanibekov effect, aka Tennis racket theorem.

P.S.: Below is a test of the operation of this simulator with a spin of the simple screw around its axis.

P.S.2: Here is a simulation of the Dzhanibekov effect. As it can be seen when the body have three distinct principal moments of inertia, rotation around one of the principal axes (associated with the second-order inertia moment) unstable. That's why the wing screw turns over.

[myc0l0gic]

taught myself to solve coupled differential equations with an actual library instead of hand writing the numerical methods like I had to do in my computational physics class last semester

[jack85200]

Read the article here!

CFD Analysis And Its Applications

[prokopetz]

Today's aesthetic: that specific era of video games right after doing 3D physics in real time became feasible but before game developers had learned when not to use it where sometimes you'd gently brush against the terrain slightly over some arbitrary velocity threshold and your character would immediately ragdoll like they'd been hit on the head.

[charyou-tree]

you're a physicist!! thats cool!! what kinda physics do you specialise in? /nf

Computational materials science. Need a software model of tungsten-copper perovskite for a new solar panel, or lithium intercalcated graphite for battery electrodes? I'm your girl.

[astrocatfizziks]

Quantum tunelling through a barrier

[quasi-normalcy]

Hey, so--we cooled your boyfriend down to a hundredth of a kelvin above absolute zero. Yeah, it was so cold that all of the chemical reactions in his body ceased. Sorry. We, uh, yeah, we used him as a dielectric material in a tiny qubit. And then we quantum-entangled him with another qubit, just to see if we could. Sorry. Yeah, anyway, we thawed him out after two weeks and apparently he's doing fine now. Didn't really teach us anything about how quantum processes work in biological systems, but it sure was, uh, cool. If you'll pardon the pun.

[bigfatbreak]

If the Kwami remember the old timeline, then Wayzz, Tikki and Plagg must remember Adrien and Marinette, right? Wouldn't they lead Fu to them? Or is something preventing Fu from doing that/Fu thinks it's too risky to make a move with Hawkmoth/Gabriel watching??

well... hm, there's kind of a problem. The timeline was mostly reset, but there are lingering echoes that things aren't right. For one, the Kwami remember the last timeline - so do the Sentikids, and in fact, so do robots/AI's of any fashion. Not only that, but some mechanisms, nonorganics, exist as though the last timeline was still in place, like passwords and lingering, half-corrupted photographs in dead links and dead blogs.

...so,

uh. ehe. oops.

[aromanrom]

Updates to projects

Introduction I didn’t post on this blog for a long time. Nevertheless, I didn’t stop the work on the projects. Most of them have improvements, some of them even serious additions. Some bugs are fixed and I even did some code cleanup to many of them. There are even a couple of newer projects on GitHub: QCSim and MachineLearning. This post is not about those, though, but about the changes and…

[andranikfakirian]

Project "CompMath.AstrophysicsODEs": Early Projects, Part 1

While the work is underway, and there is not much to show, it was decided to present examples of past projects in the field of computational physics. They were manufactured in the same way as the planned project: an integration solver on C++ language, a visualizer on Python… It's not appropriate to leave this blog for a long time without any content at all.

The first simple project from the field of applied physics was devoted to modeling a double pendulum using Lagrangians. This is a good example from chaos theory, representing the effect when the slightest changes in the initial conditions lead to a completely different behavior of the system.

P.S.: Below is an animation of two double mathematical pendulums with a bit different initial conditions (the second pendulum has a more elevated second end).

P.S.2: Here is an animation of two double pendulums, but with a much heavier second end. Apparently, this causes a more predictable behavior of the double pendulum, allowing it to be interpreted as a pendulum inside a pendulum.

[kurikorso]

oh shit look who it is!!

please click him for better quality