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John F Wu

@jwuphysics.bsky.social
4K followers 686 following 1.4K posts

Tenure-track astronomer working on galaxies, machine learning, and AI for scientific discovery. Opinions my own. He/him. Website: jwuphysics.github.io

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John F Wu @jwuphysics.bsky.social · 09/10/2026
Update: Baltimore confirmed the best. Neighbor Ms. Ruth is the best.
Picture of a slice of lemon pound cake, partially cut.
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John F Wu @jwuphysics.bsky.social · 09/10/2026
Reason number 829 that Baltimore is the best: a neighborhood grandma randomly knocks on your door and hands you a giant lemon pound cake
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John F Wu @jwuphysics.bsky.social · 08/10/2026
why does my toddler remind me of Susie from Calvin and Hobbes
my two year old just toddlin
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John F Wu @jwuphysics.bsky.social · 02/10/2026
I can't stop it's too much fun
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John F Wu @jwuphysics.bsky.social · 02/10/2026
By popular demand, I wrote a blog post explaining the web app that I built last week: the Galaxy Manifold. jwuphysics.github.io/blog/2026-10...
A preview of the Galaxy Manifold page at https://galaxy-manifold.github.io, showing the SFR-stellar mass correlation with galaxy image cutouts on a grid.
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John F Wu @jwuphysics.bsky.social · 25/09/2026
By popular demand: you can now filter out galaxies colored by missing values! In this case, I'm showing sSFR vs Mstar, colored [and filtered] by HI/Mstar. galaxy-manifold.github.io#p=ssfr&c=log... (Also, this is what it looks like on a desktop, not mobile.)
A computer-based browser view of galaxies in the specific SFR against stellar mass relation, colored by gas richness from blue (most gas-rich) to red (most gas-poor). It shows a smattering of points along the sequence of star-forming galaxies, and then a second small population of red-sequence galaxies at low sSFRs. There are very few at the bottom here because they are generally gas poor, and have thus been filtered out using the new capability on the web app.
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John F Wu @jwuphysics.bsky.social · 25/09/2026
Built a thing that #aatrosky may enjoy: galaxy-manifold.github.io
The galaxy SFR - stellar mass sequence shown on a phone screen, with galaxy image cutouts as well as lines showing the relation for galaxies based on subselections in Dn4000 break strength. All from the web app.
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John F Wu @jwuphysics.bsky.social · 09/09/2026
presented without comment
screenshot of google saying "Cleveland Guardians (33-37) at Baltimore Orioles (6-4)". The numbers in parentheses are nominally their win-loss records...
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John F Wu @jwuphysics.bsky.social · 30/08/2026
Celebrating the Roman launch!
Selfie of me and my two kids, with all of our Roman Space Telescope swag, cheering on the Roman launch.
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John F Wu @jwuphysics.bsky.social · 22/08/2026
6 packs non-alcoholic beers: Sam adams, best day, and athletic Oktoberfest, and also another of athletic mango picante
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John F Wu @jwuphysics.bsky.social · 18/08/2026
It was beyond comprehension.
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John F Wu @jwuphysics.bsky.social · 12/08/2026
Eclipse. Ten years of marriage.
A view of the sunset total eclipse over water, off the coast of Mallorca.
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John F Wu @jwuphysics.bsky.social · 28/07/2026
Having grown up in Sulphur, Louisiana, I can verify that this wikipedia picture of "downtown" is a representative view of Sulphur
A screenshot of Sulphur's wikipedia page. The headline picture is a rainy small town intersection with a few street signs and like two low rise buildings. There is one car on the road and two parked.

The rest of the page can be read at the link but it just says:

Sulphur, Louisiana
City in Louisiana, United States

Not to be confused with Port Sulphur, Louisiana.
Sulphur is a city in Calcasieu Parish, Louisiana, United States. The population was 21,809 in 2020. Sulphur is part of the Lake Charles metropolitan statistical area.

Quick facts Country, State ...
History
Sulphur is named for the sulfur mines that were 
[...]
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John F Wu @jwuphysics.bsky.social · 17/07/2026
Gonna J-lens the crap out of that first and only token
Ornate "The" from SpongeBob meme
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John F Wu @jwuphysics.bsky.social · 15/07/2026
Okay fine now it's kind of uncomfortable in Baltimore (46C heat index)
Wunderground website showing the current temperature in Baltimore as 98F and with heat index of 115F. The map nearby shows stations reporting between ~97-103F degrees in Baltimore.
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John F Wu @jwuphysics.bsky.social · 11/07/2026
I don't think I've ever seen a soccer throw-in bat flip
Basallo bat flipping like a soccer throw-in toward his own dugout after his go-ahead home run in the bottom of the 8th
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John F Wu @jwuphysics.bsky.social · 10/07/2026
Winds are starting to pick up now and the eye is showing up on radar. Bavi is a ridiculously large storm!
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John F Wu @jwuphysics.bsky.social · 10/07/2026
Here we go!
Radar from Taiwan showing heavy rain over northern Taiwan, and multiple rain bands offshore from Typhoon Bavi.
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John F Wu @jwuphysics.bsky.social · 08/07/2026
I need to find @depthsofwikipedia.bsky.social while holding this in my hand (just eaten in Ningxia night market)
Me holding a night market street food classic, "大腸包小腸" aka "small sausage in large sausage"
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John F Wu @jwuphysics.bsky.social · 01/07/2026
Loeb's team will report to a new White House panel focused on UFOs, now often referred to as unidentified anomalous phenomena, or UAP. 

"lt's like a detective story," Loeb said in an interview. "It's a lot of fun, as long as you don't pay too much attention to the ~~critics."~~ facts

Note: "critics" is crudely crossed out and replaced with "facts"
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John F Wu @jwuphysics.bsky.social · 29/06/2026
Views of National Taiwan University and the city of Taipei, from my office building in the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA).
A view of the National Taiwan University from a high observation deck, overseeing the famous Drunken Moon Lake and a few other buildings, with mountains on the back.
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John F Wu @jwuphysics.bsky.social · 27/06/2026
Can confirm, Baltimore was buzzing today
Upward point photo shows the flags up on a tall ship and seven jets flying in formation with red white and blue colored trails.
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John F Wu @jwuphysics.bsky.social · 27/06/2026
Not like Baltimore is much better...
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John F Wu @jwuphysics.bsky.social · 27/06/2026
So excited to give a colloquium in Taiwan... hm let's see what to pack based on the weather
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John F Wu @jwuphysics.bsky.social · 26/06/2026
How you know you married the right one
Orioles city connect Nike air max
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John F Wu @jwuphysics.bsky.social · 20/06/2026
Flattering, I guess
JOHN F. WU

ASTRONOMER AND DATA SCIENTIST

> 237 STRENGTH TOP 25% <

CLAUDE OPUS 4.8 SAYS ASTRONOMER AT THE SPACE TELESCOPE SCIENCE INSTITUTE FOCUSED ON GALAXY EVOLUTION, MACHINE LEARNING, AND APPLYING AI/DEEP LEARNING TO ASTROPHYSICAL DATA.

With a bar chart showing (presumably how much each model knows about "John F. Wu" from 0-100%):
GPT-5.5 0%
GPT-5.4 MINI 0%
CLAUDE OPUS 4.8 ~60%
CLAUDE HAIKU 4.5 0%
GROK 4.20 ~75%
GEMIΝΙ 3.1 LITΕ 0%
KIMI K2 0905 ~85%
DEEPSEEK V4 ~95%
LLAMA 3.3 70B 0%
LLAMA 3.2 1B 0%
GLM 4.7 FLASH 0%
MISTRAL 3.2 24B 0%
QWEN3 8B 0%
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John F Wu @jwuphysics.bsky.social · 17/06/2026
Pinging @depthsofwikipedia.bsky.social Mostly just because of "Liking for gravy" with an arrow, annotated 20th C., pointing to the UK, and "A novelty Pizza topping" for some reason off the coast of Oman?
A map with block diagram arrows pointing around how Tikka Masala spread.

Caption: Evolution of chicken tikka masala as a multicultural British dish.[41][4] Chicken tikka was created in Mughal India using Persian marinading of meat in yoghurt and Central Asian tandoor roasting with Indian spices.[42] In 20th century Britain, a sauce was added to meet the British liking for gravy with meat.[12] The dish has evolved further to a taco filling in the US,[36] and to a pizza topping in India.[39] Tacos originated from Mexico.[43] Pizzas originated from Italy.[44]


From: https://en.wikipedia.org/wiki/Chicken_tikka_masala#/media/File:Evolution_of_Chicken_Tikka_Masala.svg
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John F Wu @jwuphysics.bsky.social · 06/06/2026
Last two panels of the SpongeBob "Stop it Patrick you're scaring him" meme:

Patrick mouthing "oooh" next to an exasperated Squidward with the text: "BALTIMORE IS A BEAUTIFUL CITY"

SpongeBob worried with hands in the air: "STOP IT PATRICK YOU'RE SCARING HIM"
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John F Wu @jwuphysics.bsky.social · 06/06/2026
Gorgeous day for Charles Street Promenade!
A couple dozen vendors and hundreds of pedestrians walking up and down N Charles St in Baltimore.
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John F Wu @jwuphysics.bsky.social · 02/06/2026
This is the worst looking photo they could snap of Mamdani 😭
New York Post full front page showing Mamdani smiling from a bicycle, with giant text "CYCLE OF HATE" and "Zo snubs Israel parade, goes on bike ride instead"
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John F Wu @jwuphysics.bsky.social · 29/05/2026
About as beautiful weather as it gets... 25C at Camden Yards
A view of Oriole Park at Camden Yards
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John F Wu @jwuphysics.bsky.social · 28/05/2026
Gemini 3.5 flash is a bit better, although I'm not sure if that's simply scaffolding
There are 3 "r"s in "stwawbewwy".
If we break it down letter by letter:
s - t - w - a - w - b - e - w - w - y ... wait, looking closely at how you spelled it:
s t w a w b e w w y
There are actually 0 "r"s in your exact spelling ("stwawbewwy") because they've all been replaced with "w"s!
(If you meant the standard spelling, "strawberry", then there are 3 "r"s: strawberry).
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John F Wu @jwuphysics.bsky.social · 28/05/2026
How many rs are there in stwawbewwy (Google search)

Response:

Did you mean: How many rs are there in strawberry
AI Overview
There are 3 "r"s in stwawbewwy (stwawbewwy).
If you spell it "strawberry," there are also 3 "r"s: strawberry!
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John F Wu @jwuphysics.bsky.social · 14/05/2026
Sounds like commuting Baltimore all right
Image of adults and kids biking, partly in a protected lane, and partly into the car lane, as they navigate around a parked car. Below it are a caption and some text from the excerpt. 

Caption of image: Adam Conway, right, directs the bike bus students around a truck unloading in the bike lane on the way to Roland Park Elementary/Middle School. (Jerry Jackson/The Banner)

Text excerpt from article: As the kids approached a red light just blocks from school, a silver Volkswagen SUV with a shiny Virginia license plate was parked and blocking the bike lane. Parents pedaled into the car traffic lane and slowed down so the kids could go around; as they did, several of the kids loudly booed the car. The idling driver’s eyes remained glued to her phone.
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John F Wu @jwuphysics.bsky.social · 03/05/2026
When life gives you 韭菜, obviously you have to make 韭菜肉包
12 handmade pork and chive buns
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John F Wu @jwuphysics.bsky.social · 16/04/2026
So cool that Annual Reviews sent me a physical volume of ARA&A 63! A great memento from when I served as a guest reviewer.
A picture of me holding the physical copy of the Annual Reviews of Astronomy and Astrophysics, Volume 63, 2025.
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John F Wu @jwuphysics.bsky.social · 11/04/2026
My 20 month old son looking like the old Indian man meme
My 20 month old son looking like the old Indian man meme
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John F Wu @jwuphysics.bsky.social · 08/04/2026
The two main findings about AI in for learning: AI impairs performance and it reduces persistence.
To preview our findings, we find that AI assistance impairs independent performance and reduces
persistence. Although AI assistance improves performance during assisted sessions, people’s perfor-
mance drops sharply once AI is removed. More strikingly, relative to the controls, participants in the AI
condition also persist less with tasks and give up more frequently. This pattern is robust and replicates
across domains. These effects emerge after a brief 10–15 minute session, raising the question of what
prolonged AI use does to human capability over time.
Our results are notable on two fronts. First, while concern about AI-induced deskilling has grown,
prior evidence has been largely correlational (Budzy ´n et al., 2025; Gerlich, 2025) or limited to small
samples (Kosmyna et al., 2025; Shen & Tamkin, 2026). Here, through a series of randomized controlled
trials on human-AI interactions, we provide the first large-scale causal evidence of this effect. Second,
we demonstrate how AI can result in loss of motivation and persistence. A rich body of literature
in cognitive science and education has shown that the capacity to regulate effort and persist through
difficulty is foundational to effective learning, and is among the strongest predictors of long-term
academic achievement, workforce adaptability, and resilience (Metcalfe & Mischel, 1999; Duckworth
et al., 2007; Maddux, 2009; Metcalfe, 2009; Andersson & Bergman, 2011; Bjork et al., 2011; Kapur, 2014;
Guiso et al., 2016; Mooradian et al., 2016). Our results suggest that AI assistance erodes precisely these
capacities. People do not merely become worse at tasks, but they also stop trying. If such effects
accumulate over months and years of AI use, we may end up creating a generation of learners who have
lost the disposition to struggle productively without technological support.
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John F Wu @jwuphysics.bsky.social · 01/04/2026
FWIW I didn't read this paper, just skimmed, so I don't know how much of the findings hinge on the *photometric* catalogs. The DESI targeting catalogs are much more conservative and don't seem to be as susceptible to shreds. The photometric catalogs on the other hand...
Example galaxy and DESI DR9 photometric catalog that "shreds" the foreground galaxy into ~10 sources.
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John F Wu @jwuphysics.bsky.social · 30/03/2026
The joy of being a STScI astronomer 🤩 Spotted at BWI airport
A scene at the BWI airport showing a zoom in of the Carina nebula
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John F Wu @jwuphysics.bsky.social · 22/03/2026
Decided to catalog the amazing deals at Lidl today
NEW LOW PRICE

picture of Kind bars: $7.49 -> now $7.48 (save 1 cent)NEW LOW PRICE

picture of quaker oatmeal: $3.97 -> 3.95
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John F Wu @jwuphysics.bsky.social · 13/03/2026
Every lunch conversation at STScI today:
text message chain, three messages, which says:
i ain't reading all that
i'm happy for u tho
or sorry that happened
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John F Wu @jwuphysics.bsky.social · 10/03/2026
To what extent are star cluster ages encoded in their environments? Congrats to my coauthors Javier Viaña, Janice Lee, Andrew Vandenburg, and the PHANGS collaboration on this paper! (and be on the lookout for a part two 👀) arxiv.org/abs/2603.07289
Figure 1 of the paper, showing 112x112 HST NUV//U/B/V/I image cutouts that are used for age-dating clusters (in this case, all around ~100 Myr).
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John F Wu @jwuphysics.bsky.social · 09/03/2026
This week I'll be delivering a talk and leading a tutorial for the Language AI in Space Sciences Workshop in Baltimore, hosted at STScI. So excited to see folks from all disciplines join the conversation -- including astronomers, engineers, computer scientists, librarians, and linguists.
Conference banner that states the text:

Language AI in Space Sciences Workshop (March 9th - 12th, 2026)

imposed over what looks like a JWST image of a galaxy cluster, and the contours that specify where some astronomy literature categories live in a UMAP-ed embedding space.
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John F Wu @jwuphysics.bsky.social · 28/02/2026
I kind of like Zitron because he had the intellectual humility to admit that he doesn't know a thing about software engineering, but he's also now staked his career on writing about how AI can't do anything (including software engineering).
Screenshot of Ed Zitron saying "Embarrassed to admit I don't know the difference!" When asked "When you say software engineers do you mean front end back end or full stack?"
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John F Wu @jwuphysics.bsky.social · 25/02/2026
Ugh, not good. FWIW, I got a better answer... got the same answer with Gemini 3.1 Pro. But lack of reliability is a big reason why I don't currently don't trust these for literature search/citations.
ChatGPT screenshot:
(Query) how many new clusters were detected by hunt and reffert

(Response) In their Gaia DR3 all-sky clustering study, Emily L. Hunt and Sabine Reffert detected a substantial number of previously unreported star clusters. Specifically:
They recovered 7 167 clusters overall from Gaia DR3 data.
Out of those, 2 387 were candidate new objects that had no counterpart in existing literature prior to their work.
Applying more stringent quality cuts yields a subset of 4 105 highly reliable clusters, of which 739 are new identifications (i.e., not previously catalogued). �
arXiv +1
Thus, the number of new clusters reported by Hunt & Reffert is either 2 387 candidate new objects in the full catalogue or 739 new highly reliable clusters depending on the reliability threshold used. �
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John F Wu @jwuphysics.bsky.social · 19/02/2026
Couldn't log in to my gas/electricity provider, and the email address on file didn't work. Clicked "Forgot email?" and entered my account number; was greeted by this...
BGE website that says "Sign in to Your Account"

Below that it says "Success! Your email is *undefined*."
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John F Wu @jwuphysics.bsky.social · 15/02/2026
Thinking enabled it right -- default free does not.
You'll need to **drive** to the car wash! 

Even though 300 meters is a very short distance (about a 3-4 minute walk), you need your car to actually be at the car wash in order to get it washed. If you walked there, you'd arrive without your car.

So drive over, get your car washed, and then you'll drive back home in a nice clean car. The short distance means it won't use much fuel, and you'll still get the benefit of the walk if you want to stroll somewhere else later!
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John F Wu @jwuphysics.bsky.social · 15/02/2026
Oof owie my claude
Walk! At only 300 meters (about 1,000 feet or roughly 3-4 city blocks), it would take you just 3-4 minutes to walk there.
Driving would actually be less efficient since you'd spend time getting in the car, starting it, driving slowly for such a short distance, parking, and then walking back home anyway after dropping off the car. Plus, your engine won't even warm up properly in that distance.
The walk will take barely any time and you'll get a bit of fresh air in the process.
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John F Wu @jwuphysics.bsky.social · 06/02/2026
Registration closes today for the Astrophysics x NLP conference! Happening March 9-12! www.stsci.edu/contents/eve... #astronomy 🔭 🧪 🌌
The Langue AI in Space Sciences Workshop logo, featuring a cutout image from JWST with a "semantic space map" from the Pathfinder paper by Kartheik Iyer et al. (2024).
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