John F Wu

Amazing stuff for #astrosci!

This is awesome! Which brewery is this?

An area of deep space with thousands of galaxies in various shapes and sizes on a black background. Most are circles or ovals, with a few spirals. More distant galaxies are smaller, down to being mere dots, while closer galaxies are larger and some appear to be glowing. Red and orange galaxies contain more dust or more stellar activity.

For the latest image of the month, the NASA/ESA/CSA James Webb Space Telescope revisits the iconic Hubble Ultra Deep Field.

The deep observations reveal more than 2500 sources sparkling in this tiny patch of sky ✨

Read more 👉 www.esa.int/ESA_Multimed...

🔭🧪
#extragalactic

Awesome work by our multidisciplinary team spanning HCI/psych/CS/astronomy and co-led by fantastic undergrads!

Learned a lot about how to better evaluate AI for science, both quantitatively and qualitatively... also how astronomers learn to (dis)trust LLMs for use in research!

#AstroSci

Results figure showing how the stellar mass prediction error decreases when (a) we use GNNs, shown in purple, and (b) add environmental context on very large scales out to 10 Mpc.

Check out my new blog post discussing graph neural networks for astrophysics—specifically, how galaxies relate to their dark matter subhalos in the context of their cosmic environments.

jwuphysics.github.io/blog/2025/07...

#astrosci

out of academia Out of Academia

I've had a few other former astronomers reach out to me lately about transitioning into data science/ML, and I decided to write about it.

This is my personal journey from astro to ocean, and the most useful steps I took along the way.

Relevant blurb from the ICML publication ethics: "Note that this use of hidden prompts is distinct from those intended to detect if LLMs are being used by reviewers; the latter is an acceptable use of hidden prompts."

icml.cc/Conferences/...

Audience seated in an amphitheater-style lecture hall, attending a presentation about space exploration, featuring visuals of a spacecraft on a large screen.

STScI's Jason Tumlinson spoke this morning about seeking our origins in the universe with the Habitable Worlds Observatory.

Scientists from around the world gathered in Washington, D.C., to discuss the search for signs of life on planets orbiting other stars. #HWO2025 🔭 🧪 ☄️

I'm no Wharton grad but I feel like the federal government shouldn't be profiting off the American people?

In case you find this useful:

Any nearby groups/clusters?

A nebula with a bright star at its center. The nebula has three distinct layers, and the pattern in the layers repeats in a way that implies there are more layers outside the image boundaries, though they would be faint. The shape of the nebula is something like nesting yin yangs, with the center smallest one bright and dense, shining, smooth and golden. The middle one is orange and textured like a sherpa blanket. The largest, outer shell is fainter, and red like an ember. Its texture has softened along with its dissipation into space. There are some small stars speckled around the image, and one annoyingly bright, spiky one that's got too many colors because of the way the light spreads from point sources through the telescope's optics. A pale haze of grayish cloud also covers the scene, but it is sheer and translucent.

Apep. JWST. It's weird. Just look at it.

From GO 5842: What lies beyond the inner spiral of Apep?
Principal Investigator: Yinuo Han

flic.kr/p/2riELBn

YouTube video by James Webb Space Telescope (JWST) Cosmic Caverns in the Cat's Paw Nebula

Literally jaw dropping.

I somehow missed this last week -- maybe you did as well! Check out the JWST 3rd anniversary courtesy of the @stsci.edu Office of Public Outreach.

www.youtube.com/watch?v=fYez...

#astrosci #astronomy

Even though I'm already past my self-imposed yearly quota for reviewing papers, I can't help but accept this latest one since it's *not* about machine learning in astronomy...

A froggy squishmallow and Elmo tucked under covers in your bed

When you and your spouse are enjoying a Friday night with a bottle of pinotage but you hear your 4 year old scampering around upstairs so you decide to investigate

The Senate just posted the report language of its FY26 science appropriations bill. This text lays out what they want done and carries the force of law if it is included in the final spending bill.

It's a line-by-line refutation of Trump's proposed budget for NASA and NOAA.

Next he'll claim that the preferred method of interstellar travel is via a sublimating spaceship

As someone who might soon fly to Montreal and will probably depart from Princeton Jct this is Very Useful Knowledge.

Also sorry to hear about the shitshow

The Discovery of Little Red Dots in the Local Universe: Signatures of Cool Gas Envelopes JWST observations have revealed a population of high-redshift "little red dots" (LRDs) that challenge conventional AGN models. We report the discovery of three local LRDs at $z = 0.1-0.2$, initially s...

Whoa. Three Little Red Dots have now been found in SDSS! arxiv.org/abs/2507.10659

But due to their compact morphology and bizarre colors, they are originally selected as *quasar candidates*, not galaxies! In any event, LRDs are not unique to the high-z universe.

#astrosci

Comic. The Three Types of Unsolved Physics Problem (First panel) Vague. PERSON [next to curved diagram] What is the nature of time in quantum gravity? Is it a background parameter, a dynamic aspect of spacetime, or an emergent phenomenon? (Second panel) Precise. PERSON 2 with short hair [device with equation below: 71Ga + νe → 71Ge + e- .] Why does the *S.A.G.E.* Gallium Neutrino Capture Experiment produce only 75% as much germanium as predicted? (Third panel) Cursed. PERSON 3 with white hat [rectangular block with hairs growing out of it labeled Zinc Whiskers] Why does some metal randomly grow hairs? It keeps causing short circuits and we have no idea what’s going on. OFF-PANEL: Is this a joke? PERSON 3: No! Please help!

Unsolved Physics Problems

xkcd.com/3115/

The Discovery of Little Red Dots in the Local Universe: Signatures of Cool Gas Envelopes JWST observations have revealed a population of high-redshift "little red dots" (LRDs) that challenge conventional AGN models. We report the discovery of three local LRDs at $z = 0.1-0.2$, initially s...

Whoa. Three Little Red Dots have now been found in SDSS! arxiv.org/abs/2507.10659

But due to their compact morphology and bizarre colors, they are originally selected as *quasar candidates*, not galaxies! In any event, LRDs are not unique to the high-z universe.

#astrosci

Exactly what I was thinking of!

It's surprisingly common for ants to get into outdoor HVAC compressor contactors, and it can definitely cause problems! Here's how it generally happens: Ants are often attracted to electrical components for a few reasons: * Magnetic Fields/Heat: Some scientists believe ants are attracted to the magnetic fields surrounding live wires or the warmth generated by the resistance in the wires. It's thought they might interpret these as signals for a good nesting spot or even a food source. * Shelter: HVAC units offer enclosed, protected spaces that are ideal for ants to build nests, especially as the weather warms up or after it rains. * Alarm Pheromones: When an ant gets electrocuted in the contactor, it can release an alarm pheromone. This chemical signal acts as a distress call, attracting more ants to the area, creating a vicious cycle and leading to a large accumulation of ants.

Okay TIL this is a common bug

Real life bugs: our outdoor heat pump compressor is full of ants and now we don't have cool air

Great thread -- please read the FULL thing!

Data Release 19 - SDSS DR19 is the second data release for the fifth phase of the Sloan Digital Sky Survey (SDSS-V). Its content is described in detail on the DR19 data release paper. What's New in DR19 Data Access Scope DR...

We have a data release! Check out sdss.org/dr19 for all the data that just became publicly available with our 19th data release #DR19

Thank you Senate for being the least unserious bit of our government

Screenshot of my new blog post, see here: https://jwuphysics.github.io/blog/2025/07/clear-vision/

The Eleven Laws of Showrunning is full of useful advice for managing a television show, from ideation to writing to production to postproduction. But there’s also a ton of guidance that’s surprisingly relevant for working with LLMs!

jwuphysics.github.io/blog/2025/07...

The notification email from COLM 2025, stating that our paper "From Queries to Criteria: Understanding How Astronomers Evaluate LLMs" was accepted.

Congratulations to our JSALT research team! Our final research paper has now been accepted to COLM 2025.

This was a truly multidisciplinary effort, with our team expertise spanning across astronomy, psychology, human-computer interactions, and AI/ML. Well done!

The optical and infrared are connected Galaxies are often modelled as composites of separable components with distinct spectral signatures, implying that different wavelength ranges are only weakly correlated. They are not. We present a da...

Also recommend checking this paper out! arxiv.org/abs/2503.03816