On the occasion of #GR24Amaldi16, all articles in the collection "Hyperboloidal foliations in the era of gravitational-wave astronomy" are free-to-read from 10 July to 10 August 2025! link.springer.com/collections/... — Don't miss today's related talks by Anna Sancassani and Benjamin Leather!

I finally got it!!! This is a finite element solution of a scattering problem using hyperboloidal compactification. A method developed in an unknown niche corner of mathematical relativity and conformal geometry is now ready for real-world problems!

Achievement unlocked 🥂 🧪: Published a technical physics paper with a philosophical opening: "What is time?" The paper addresses an aspect of this timeless question in a rather technical sense: How should we construct time in GR with its black holes and observers? link.springer.com/article/10.1...

This is the language used for DEI in a letter from the Office for Civil Rights: "a shameful echo of a darker period in this country's history." Times are changing.

In general relativity, general covariance applies only to coordinate systems related to each other by smooth transformations. In the presence of boundaries, general covariance is explicitly broken. Gauge-fixing must consider the boundary structure.

A horizon is a limiting surface of no return. It's the boundary beyond which interaction is impossible. We can send signals beyond the horizon but can never receive signals back. Famously, black holes were the first relativistic horizons we discovered. The event horizon is a surface of no return. 🧪

Buying quantum computing stocks is all fun and games until you remember that Gutenberg was practically bankrupt because of his printing press.

New paper the cites the BHPToolkit: "Gravitational self-force with hyperboloidal slicing and spectral methods" by Benjamin Leather, arxiv.org/abs/2411.14976

We live in hyperbolic times. So here's a paper about hyperbolic times, fresh off the press, published just yesterday. https://buff.ly/3OjsJi3

We live in hyperbolic times indeed. Here's a paper about hyperbolic times, fresh off the press, published just yesterday. pubs.aip.org/aapt/ajp/art...

Paper day! My article on counterintuitive properties of accelerated motion is out in Am. J. Phys. (It's Open Access, and also an "Editor's pick," yay!) 🧪⚛️🎢 - things like "two objects that keep a constant distance from each other can still be in non-zero relative motion!"

If you've got a clear view of the Eastern sky, step outside for a few minutes. There's a lovely alignment of the moon, Jupiter & Aldebaran. (a red giant 44x the diameter of the sun)

Why are people who get excited about precision metrology fired up about the prospect of a clock based on thorium? (PM repost) open.substack.com/pub/chadorze...

Reminder for new users here: Quantum physics is not only the physics at small scales. There are macroscopic quantum phenomena.

People who study relativity like to "conformally compactify" spacetime, creating a finite patch of coordinates, and attaching a boundary. This makes it possible to talk about going to "infinity" more precisely. This turns Minkowski space into what they call a "diamond". 🧪⚛️ #🧮

I'll start! I'm looking forward to seeing arxiv announcements, explainer threads, deep technical discussion happening in the comments that I don't understand, and of course overly niche shitposts

New article: "The geometry of data: the missing metric tensor and the Stein score" (blog.christianperone.com/2024/11/the-...). I show how you can derive a (efficient to compute) data manifold metric tensor with the Stein score alone ! Deep connections to diffusion, score-based models and physics.

The Stokes phenomenon, animated! Highlighting the integration contour for evaluating an integral (for the Airy function) in the saddle point / stationary phase method. Inside the left Stokes wedge, two saddle points contribute; outside, only one (more details in alt text). 🧪 #🧮

Last week, Ollie Burke and I put out a note describing how to convert between all the different orbital phases used to describe orbits around a spinning black hole. The most fun reason to do this is. to help make visualisations like this one arxiv.org/abs/2411.04955

An interesting idea: information communication can be viewed as information storage. Sending a message across space is similar to storing it over time.

Here's the beginning of starter pack for people and groups working on the theory, detection, or analysis of gravitational waves, or whose work is closely related to the field of gravitational waves. Please let me know who I've missed and I'll add them. go.bsky.app/HrAJX35

I picked up an interesting idea from a seminar by Marina De Amicis about black hole perturbations Quasinormal modes deliver small scale information to the observer, whereas the tail delivers large scale information. The tail is a memory effect telling you what perturbed the spacetime long time ago

One great use case of ChatGPT for me has been in making figures. These turned out pretty.

I wrote a technical guide on solving wave equations on unbounded domains. The idea is to map the unbounded domain to a bounded domain. The trick is to combine spatial mapping with a transformation of time. Code is included in Google Colab. anilzen.github.io/post/2023/wa...

What's the relativistic analog of a soap bubble? It's a hyperboloid. Soap bubbles are minimal surfaces. They minimize area to enclose a given volume of air. Similarly, hyperboloids maximize volume to enclose a given spacetime volume. anilzen.github.io/post/2023/sp...

Infinity is the ideal boundary of space.

"If you want to understand the universe, start out by understanding the soap bubble." Great lecture by Frank Morgan www.youtube.com/watch?v=Cbpf...

Space emerges as quantum foam from the dual boundary.

The topical collection for research in hyperboloidal foliations is open for submission! link.springer.com/collections/...

New, powerful quantum error-correcting codes could help hasten the arrival of useful quantum computers.