bog
不停循环的时间
失去人的痛会把你紧紧地困进一圈不停循环的时间。
日历收走，只留着一座钟。
每一天是那一天，
全世界取模24。Dichotomies of physics
Revolutions in physics are forever memorialized by the dichotomies they introduce. While the hot new topics are given trendy labels of “quantum” or “relativistic” or whatnot, the old established players are relegated to the catch-all drawer of “classical stuff”. As with all human endeavors in categorizing things, these divisions should not be interpreted too rigidly. Some of the most interesting work in physics is done at their intersections. Conversely, these relatively modern divisions should not be regarded as the only useful ones. I want to bring up a less glamorized, yet no less important dichotomy which cuts across the more popular labels: the discrete versus the continuous.
The background of the universe
When we try to picture the cosmos, we tend to only think about the shiny stuff — stars, galaxies, and very very hungry black holes. But stars cannot burn their hearts without cold hydrogen to collapse from, cannot coalesce into galaxies without dark matter to pull them together, and cannot shine as black holes after death without more gas and dust to feed on. The background medium, as it turns out, has as much tremendous importance to astronomy as the objects underneath the spotlights.
December 2023
decision paralysis but also,
recognizing in a finite lifespan I
get to pick a few things out of an
infinitude to savor is kinda neatA rough sketch of gauge theory
November 2023
in summary, month of reading too many things
AdS-CFT
Cracks
What is the Hubble Tension?
This post was adapted from this presentation I gave for UC Berkeley’s Undegraduate Astro/Physics Laboratory (ULAB). Check that out for fancier graphics.
Redshift surveys
Watching fly-throughs of galaxy maps reminds me of shining a flashlight in a dusty room; the illuminated particles, each clinging on tight to its own little world of unfathomably many tiny creatures, dance chaotically on the dark undercurrents of air. By observing their Brownian motion, Einstein was able to deduce the atomic nature of the unseen medium.
Decanting
Notes on Carroll & Ostlie, Introduction to Modern Astrophysics, parts I & II
My notes for the first two parts of Carroll & Ostlie’s “Big Orange Book”, written in a combination of markdown and LaTeX for the optimal mix of accessibility and mathematical typographic beauty, are available at xingyzt.net/notes/intro-to-modern-astrophysics. Enjoy studying the universe!
{}
They call the piece a Set, the basic boundary between an Inside and an Outside.
Polarizar: Visual odometry for the 2023 FTC robotics competition
The problem: Our robot needs to precisely navigate a field of poles.
really bad Gilgamesh scifi fanfiction
The Space Epic of Gilgamesh
Mapping Arcadia High: Painting a voxel world
The idea was to use the native WebGL mesh rasterizer instead of the custom distance-field-accelerated raymarching algorithm for the initial rays cast into the scene, while keeping the raymarching for the secondary bounces. At first, this was done with plain mesh rasterization into 1x1 quads, but even with overlap and normals culling, mesh rasterization performs approximately 2x worse than SDF raymarching. So I had to simplify the mesh. By using a greedy voxel meshing algorithm popularized by Mikola Lysenko, I was able to significantly reduce the number of polygons, and the performance shifted in the mesh rasterizer’s favor. Without reflections, the mesh rasterizer with a simplified mesh performs approximately 1.5x to 2x better than SDF raymarching.
Curtain
Mie
Browser extension scams
As a dev of Mercator Studio, an extension with ~10k users, I get 3-4 emails a month in my spam which ask me to monetize my extension by secretly changing its users’ search engines. Mercator is open-source and quite small, but if the change was sneaked in I think most of the users would not notice. I stick to using userscripts for the most part since you can easily check their downloaded source and disable updates.
Rippleweave: Swirls of math
Gorman’s Hill
Koipond
flipbrain
Planetary Adventures with Ballsy McBallface
Curiosity
First Avenue Middle School
subscribe via RSS