sritchie (u/sritchie)

sritchie commented on North America Is Dripping from Below, Geoscientists Discover jsg.utexas.edu/news/2025/... · Posted by u/jandrewrogers

zerealshadowban · 5 months ago

it usually starts with a stalactite, then a stalagmite; by the way is there a mnemonic for the two words in English? something like t for tumbling and m for mounting...

sritchie · 5 months ago

I always remember it with “g” for ground and “c” for ceiling… haha but I do like the mites and tites one too in a neighbor comment :)

sritchie commented on Ice to treat soft-tissue injuries contraindicated by creator of protocol en.wikipedia.org/wiki/RIC... · Posted by u/stank345

Swizec · a year ago

Ice is good for muscle recovery immediately after strenuous activity. Within minutes is best, up to an hour or so is still effective. After that you need warmth.

Strenuous here means lifting your one rep max, running 20 miles, breaking a personal best sprint time, that sort of thing.

I can attest from personal experience that ice bath right after exercise works in these cases. I’ve even tested it by icing just one leg and not the other. There is a marked difference in recovery by next day.

Ideally you ice the muscles right after workout then put them in a compression clothing so they’re extra warm for the next several hours.

sritchie · a year ago

I think the idea is that you performed the exercise to create stress that you want your body to respond to by getting stronger / more aerobically fit etc in some way. So by icing, yes, you recover better, but by reducing the stress you reduce the adaptations.

Imagine you could perfectly recover with some intervention. Then weight lifting no longer works!

For examples like the ones you listed, peak performances where you’re not concerned about gainz and maybe even have to perform again soon after, it makes a lot of sense to do anything to recover quickly.

sritchie commented on The Emmy Computer Algebra System github.com/mentat-collect... · Posted by u/tosh

cashsterling · 2 years ago

Simply want to say thank you and you're awesome. I'm looking forward to the physics lessons.

sritchie · 2 years ago

Thank you for the kind words :)

sritchie commented on The Emmy Computer Algebra System github.com/mentat-collect... · Posted by u/tosh

amelius · 2 years ago

> Having the system in Clojure offers a number of advantages. It is not necessary to obtain or prepare a MIT/GNU Scheme executable to execute: only a Java runtime is required.

I still wonder if that is the easiest way to go about it. Isn't it possible to compile Scheme to WASM, for example?

sritchie · 2 years ago

Not MIT scheme, and there are no proper ports of scmutils to other Scheme dialects that I know of.

sritchie commented on The Emmy Computer Algebra System github.com/mentat-collect... · Posted by u/tosh

nerdponx · 2 years ago

It's a weird argument to me that somehow obtaining a Java runtime environment is easier than getting a binary for a Scheme interpreter. I think most people who aren't already Java users would find the latter easier, not the former.

sritchie · 2 years ago

That note in the docs is from a time when Emmy only ran on the JVM. Now Emmy runs in JS in a browser (see my top level comment for demo links) which I would argue is even easier.

Also the MIT scheme install was historically quite hairy and not supported on M1 Macs, for example.

I’ll update the docs here. Thanks!

sritchie commented on The Emmy Computer Algebra System github.com/mentat-collect... · Posted by u/tosh

surprisetalk · 2 years ago

Hey, this is Sam Ritchie's project! Here's some of his excellent tech talks:

• "Computational Physics, Beyond the Glass" by Sam Ritchie (Strange Loop 2023) - YouTube: https://www.youtube.com/watch?v=Jv2JgzAl5yU

• "Emmy: Moldable Physics and Lispy Microworlds" by Sam Ritchie - YouTube: https://www.youtube.com/watch?v=B9kqD8vBuwU

• "Just-So Stories for AI: Explaining Black-Box Predictions" by Sam Ritchie - YouTube: https://www.youtube.com/watch?v=DiWkKqZChF0

At one point he was rebuilding an old airplane. Unsure if that project is still going on:

• https://samritchie.io/spring-clips-and-stage-time/

sritchie · 2 years ago

Hey Taylor, thanks for posting these!! I'm still working on the airplane... it's a Vans RV-10, and now out at the hangar and maybe 98% complete, one more full-time month of work that I need to carve out so I can fly it by this summer.

sritchie commented on The Emmy Computer Algebra System github.com/mentat-collect... · Posted by u/tosh

sritchie · 2 years ago

Co-author of Emmy here, happy to answer any questions!

Point well taken from tonyarkles that on-boarding and docs need work. My big goals for this project were:

1. finish a 100% port of Gerald Sussman's scmutils algebra system into the browser via ClojureScript (I'm at ~98% or so?)

2. attach a 2D and 3D visualization system, and use the very-high-level physics abstractions to generate fast, interactive animations

3. make this all editable in the browser

4. write a ton of physics lessons and essays using the system

1-3 are all done, 4 is going to happen, but job + young twins are slowing me down now.

The easiest way to play with 1-3 is via the demos I shared at Strange Loop this past year, all of which run in the browser.

The first two live in Maria.cloud, which has all of Emmy available on any page. So fork these, play and share:

- First-Class Visualizations: https://2.maria.cloud/gist/30dbb25a2d2eb7324e0aad1097c459ae

- MathBox + Emmy at Strange Loop: https://2.maria.cloud/gist/0405c3427c88326a181b307371f939bc

These live in an editable version of a Clerk notebook with a less-polished UI:

- Taylor Series: https://sritchie.github.io/strange-loop-2023/notebooks/stl/t...

- Dual Number Visualization: https://sritchie.github.io/strange-loop-2023/notebooks/stl/d...

- (p, q) torus knot: https://sritchie.github.io/strange-loop-2023/notebooks/stl/p...

- Phase Portrait of the Pendulum: https://sritchie.github.io/strange-loop-2023/notebooks/stl/p...

- Geodesics of a Torus: https://sritchie.github.io/strange-loop-2023/notebooks/stl/t...

- Geodesics Klein bottles: https://sritchie.github.io/strange-loop-2023/notebooks/stl/k...

- Animated Particle on an Ellipsoid: https://sritchie.github.io/strange-loop-2023/notebooks/stl/e...

sritchie commented on Check Out These Self-Soldering Sleeves from World War II hackaday.com/2024/01/31/c... · Posted by u/rcarmo

cuSetanta · 2 years ago

The NASA workmanship guides provide a great set of options for various methods: https://workmanship.nasa.gov/lib/insp/2%20books/links/sectio...

sritchie · 2 years ago

I used tons of lash splices while building an RV-10 airplane but didn’t know the name until now. Thank you!

sritchie commented on Learn Physics with Functional Programming nostarch.com/learn-physic... · Posted by u/privong

chunsj · 2 years ago

If it has an implementation of reverse mode automatic differentiation, then it might be possible.

sritchie · 2 years ago

I have reverse-mode (purely functional reverse mode at that!) sitting in a branch, and will get this going at some point soon. Even more fun will be compilation down to XLA, like JAX does in Python.

sritchie commented on Learn Physics with Functional Programming nostarch.com/learn-physic... · Posted by u/privong

tikhonj · 2 years ago

It would let you represent physical systems as normal Haskell functions and get accurate derivatives "for free". At least in the one-dimensional case it's probably simpler than numeric differentiation while also letting you worry far less about accuracy and stability.

I've never worked this through to a full conclusion, but you could even write it in a way that would let you get symbolic differentiation out of it too.

sritchie · 2 years ago

Yes, if you get to automatic differentiation by overloading your operators to also take a “differential” type, you can further overload them to do symbolic arithmetic and then symbolic differentiation falls out for free.

See https://sritchie.github.io/emmy/src/emmy/differential.html for detail!