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Robert Fisher

@fisherastro.bsky.social
525 followers 408 following 81 posts

Caltech-UC Berkeley-LLNL-Chicago-UMass Dartmouth. Sabbatical 23-24 @ Institute for Advanced Studies and Heidelberg Institute for Theoretical Studies. American & Italian Theoretical and Computational Astrophysicist. Professor. He/him/his.

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Robert Fisher @fisherastro.bsky.social · 23/01/2026
Well-deserved congratulations!!
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Robert Fisher @fisherastro.bsky.social · 03/11/2025
This was done with @anthropic.com's Claude Code. You can grab the code yourself here: github.com/rtfisher/tor... .
github.com
GitHub - rtfisher/torque-free-rigid-rotation: Python simulator for torque-free rigid body rotation with dual-frame visualization
Python simulator for torque-free rigid body rotation with dual-frame visualization - rtfisher/torque-free-rigid-rotation
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Robert Fisher @fisherastro.bsky.social · 03/11/2025
I have been experimenting with large language models to "collaboratively" write code to illustrate key physical concepts for my junior-level mechanics class for physics majors. It did a very nice job in generating an animation of the "tennis racket theorem."
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Robert Fisher @fisherastro.bsky.social · 28/10/2025
We're hiring a teaching physics professor! Our campus feels like a liberal arts sized college within a research university. Our current teaching faculty teach first year to graduate level courses and mentor undergraduate and graduate research students. careers.umassd.edu/en-us/job/52...
careers.umassd.edu
Details - Assistant/Associate Teaching Professor - Physics
Discover exciting career opportunities at UMass Dartmouth. Join our diverse team and make a difference. Explore job openings now at UMassD!
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Philip Mocz @philipmocz.bsky.social · 14/09/2025
I noticed Google search is no longer reliable for quick unit conversions & calculations. So I built a simple online calculator Give it a spin: pmocz.github.io/online-unit-...
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Robert Fisher @fisherastro.bsky.social · 23/08/2025
Definitely one way to run out of Gauss.
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Robert Fisher @fisherastro.bsky.social · 18/08/2025
Generative AI is rapidly progressing and threatens to inundate us. A new paper (including my old Caltech classmate Serge Belognie) utilizes noise-encoded illumination to “watermark” live video. It offers some hope for those concerned for team reality. arxiv.org/abs/2507.23002 h/t @truesciphi.org
arxiv.org
Noise-Coded Illumination for Forensic and Photometric Video Analysis
The proliferation of advanced tools for manipulating video has led to an arms race, pitting those who wish to sow disinformation against those who want to detect and expose it. Unfortunately, time fav...
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Chanda Prescod-Weinstein 🌌 @chanda.blacksky.app · 28/07/2025
📣📣 BOOK NEWS 📣📣 I'm excited to share the cover and release date of Book #2, #EdgeOfSpaceTime, which is now available for PREORDER!! You can order from ANY bookstore, including your local indie! More details on preordering here: www.penguinrandomhouse.com/books/746817... What's the book about? 🧵
[neon rainbow pattern background]
THE EDGE OF SPACE-TIME

The universe reimagined -- through pop culture, poetry, and theoretical physics.

From the award-winning author of The Disordered Cosmos

image of the cover of the book which features circular artwork in the center, one half of it a black and white pattern and the other half a neon rainbow pattern

PREORDER NOW Coming 4/7/26 
image of the Pantheon logo
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Robert Fisher @fisherastro.bsky.social · 27/07/2025
It's always great to see the successes of former students. Postdoc Chris Byrohl @cbyrohl.bsky.social, whom I've known he was an undergraduate, published an amazing paper this week on his new GPU accelerated Ly-α radiative transfer code THOR Hugely impressive results! arxiv.org/abs/2507.11603
Application of THOR raytracing and Lyman-alpha MCRT for a highly-resolve, high redshift galaxy formation simulation at z = 6.
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Robert Fisher @fisherastro.bsky.social · 07/05/2025
Definitely a huge challenge but I know we will eventually get there. It's something I also confronted when teaching math methods; software systems have been better at doing integrals than introductory students for decades, but that doesn't mean we have stopped teaching calculus.
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Robert Fisher @fisherastro.bsky.social · 07/05/2025
They are extremely useful for many tasks -- from generating comments to code or git commits to developing perfectly formatted figures. But they are improving so rapidly we cannot really ignore them. A new generation of agentic tools like Claude Code are already here.
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Robert Fisher @fisherastro.bsky.social · 04/05/2025
Experimenting with the @anthropic.com Claude Code command line beta. In some ways, it is a natural extension of the familiar chat LLM interface. In others, it offers a brief glimpse of more agentic AIs to come -- building and running code and analyzing results largely on its own.
Sample output from the Claude Code beta command line for the Flash astrophysical hydrodynamics code.
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Robert Fisher @fisherastro.bsky.social · 25/04/2025
¡Todavía tengo el vinilo original!
Original Grace under Pressure album.
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sanjana! @sanjanacurtis.bsky.social · 15/04/2025
Really cool opportunity for advanced grad students and postdocs to learn about and discuss multi-messenger astrophysics in beautiful Santa Cruz! (featuring yours truly)
4th Santa Cruz School on Multi-Messenger
Astrophysics, July 11-20, 2025

Sponsored by the NSF Physics Frontier Center N3AS

Intended for advanced graduate students and beginning postdoctoral researchers interested in nuclear and particle astrophysics - theory, experiment, or observation

Apply Online N3AS.berkeley.edu/summer2025

Application Deadline June 6, 2025

Support available to cover participants' local costs

Speakers include:
John Beacom (Ohio State)
Astrophysical Neutrinos: Sources and Detection
Sanjana Curtis (Oregon State)
The Origin of Milky Way Elements
Rahul Kannan (York University)
Simulating the First Billion Years of Cosmic Time
Dan Kasen (UC Berkeley)
Mergers and Kilonovae, and what they tell us about Nucleosynthesis
Spencer Klein (Lawrence Berkeley Lab)|
IceCube and Beyond: Ultra-High Energy Neutrinos
Rocky Kolb (U Chicago) |
The Standard Cosmological Model
Adrian Lee (UC Berkeley)
What we have & could learn from the Cosmic Microwave Background
Chung-Pei Ma (UC Berkeley)
Ultra-massive Black Holes and their Gravitational Waves
Dominic Pesce (CFA, Harvard)
Exploring the Universe in Radio Waves
Matt Pyle (UC Berkeley)
Dark Matter Experiment
Sanjay Reddy (U Washington)
Neutron Star Properties; Neutron Stars as Physics Laboratories
Dave Schlegel (Lawrence Berkeley Lab) First Results from the Dark Energy Survey Instrument

Location: University of California, Santa Cruz
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Robert Fisher @fisherastro.bsky.social · 11/04/2025
Hope the historic Orrery made the cut!
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Robert Fisher @fisherastro.bsky.social · 08/04/2025
My research group alumna, Mckenzie Ferrari has made her debut contribution to the astronomy reader's digest Astrobites! In her engaging review, Mckenzie dives into a paper exploring the origins of astronomical candles that shine a bit too brightly. aasnova.org/2025/04/08/s... 🔭🧪
aasnova.org
Shedding Light on Candles That Burn a Bit Too Bright
Astrobites reports on how standard candles might not be quite as standard as previously thought, and how a particular type of supernova is making a name for itself.
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Robert Fisher @fisherastro.bsky.social · 30/03/2025
This looks cool!! The postdocs and students at @hitsters.bsky.social developed a Habitable board game last year while I was there. There was a limited run of physical copies, but there is a version available online for free. tabletopia.com/games/habita...
tabletopia.com
Habitable
This is Habitable, a fun deck-building game where players try to find planets, make them habitable, keep them habitable, and make life flourish. We are an international team of astrophysicists
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Robert Fisher @fisherastro.bsky.social · 24/03/2025
The ESA Gaia mission mapped out the positions and velocities of over a billion stars in our galaxy and led directly to dozens of breakthrough investigations in stellar astrophysics. Godspeed.
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Robert Fisher @fisherastro.bsky.social · 06/03/2025
When I was a teaching assistant for Alex Filippenko’s large introductory astronomy course, Alex solicited us (the TAs) for exam questions. The end product was some combination of the best questions from both Alex and the TAs.
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Robert Fisher @fisherastro.bsky.social · 02/03/2025
Kramers and Holst (1923) captures the brief "old quantum mechanics" of Bohr and Sommerfeld in beautiful illustrations. archive.org/details/atom... Ht/Paul Prudence
Schematic diagram of the outermost Bohr orbitals of sodium, showing elliptical orbitals.A schematic diagram of the Bohr orbitals of radium (atomic number 88), showing the symmetric nature of the full shells of elliptical orbitals.A schematic diagram of the formation of a hydrogen molecule. The diagram shows two hydrogen atoms approaching one another in three stages, finally resulting in the two electrons orbiting one another in a circular orbit, with the protons some distance away to either side.
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Robert Fisher @fisherastro.bsky.social · 17/02/2025
Pre-tenure: ~ 1 course per semester. Post-tenure: ~ 1 course / 5 years.
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Robert Fisher @fisherastro.bsky.social · 13/02/2025
I usually do this as a homework assignment, but it could work in-class: given stellar data, “discover” the HR diagram by plotting mags and then abs mags versus colors. Also interactively see the difference between a magnitude and volume limited sample.
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Robert Fisher @fisherastro.bsky.social · 08/02/2025
Indeed, we had a preview of what a sudden endowment shortfall looks like — Harvard for instance couldn’t even afford to put breakfast on the table for their students. That is precisely their goal here.
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Robert Fisher @fisherastro.bsky.social · 03/02/2025
Very cool, thanks!
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Robert Fisher @fisherastro.bsky.social · 02/02/2025
Is this a Seestar?
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Robert Fisher @fisherastro.bsky.social · 28/12/2024
There's actually quite a literature surrounding hypothetical "neutrino balls," going back at least to Holdom, 1987 (journals.aps.org/prd/abstract...).
journals.aps.org
Cosmic balls of trapped neutrinos
Fermions trapped inside a closed domain wall may cool to degeneracy and form a long-lived structure. In the context of spontaneous left-right-symmetry breaking, we show that trapped right-handed neutr...
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Robert Fisher @fisherastro.bsky.social · 24/12/2024
Dan Scolnic posted about it on the other side. x.com/dscol/status...
x.com
x.com
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Robert Fisher @fisherastro.bsky.social · 23/12/2024
OS/X (both Intel and silicon) is currently supported, but only minor tweaks will be needed for Windows. github.com/rtfisher/sni...
github.com
GitHub - rtfisher/snid_docker
Contribute to rtfisher/snid_docker development by creating an account on GitHub.
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Robert Fisher @fisherastro.bsky.social · 23/12/2024
The requisite legacy PGPLOT library is automatically downloaded and installed with X-Windows interface support. The container hosts the X11 server which the user can easily connect to via a local X11 client on their desktop. The best part is this is all accomplished by running a single script.
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Robert Fisher @fisherastro.bsky.social · 23/12/2024
I’ve written a short Docker file to easily enable anyone to run Blondin & Tonry’s SuperNova IDentification (SNID) code on almost any platform. (1/2)
A screenshot of SNID-Docker running on OS/X.
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Robert Fisher @fisherastro.bsky.social · 19/12/2024
@kanopyofficial.bsky.social is widely used at universities and public libraries in the US. www.kanopy.com/sites/defaul...
kanopy.com
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Dr. Skylar Grayson @skylargrayson.bsky.social · 10/12/2024
Periodic reminder that the sun isn’t going to explode. It will slowly ploof out and completely wreck the inner solar system in ~5 billion years but a ploof is very different from a boom. The sun (as crazy as this seems when you think about how big the sun is) is too small to go supernova
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Robert Fisher @fisherastro.bsky.social · 07/12/2024
So many Weinberg gems in this talk. This one slide distills the essence of his approach to science wonderfully. As someone who interacts primarily through the command line still, I feel for the loss of the “good old days” of MS-DOS. 🙂
A short bullet point list titled “Some of Steve’s distinctive qualities as a researcher” from John Preskill’s talk. One example “Not a visual thinker : He had little use for figures (reluctant migration from MS-DOS to Windows).”
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Robert Fisher @fisherastro.bsky.social · 01/12/2024
Forgot to tag @vmehta-astro.bsky.social !
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Nilesh Trivedi @nilesh.trivedi.link · 29/11/2024
floss.fund is offering $1 million per year grant to open-source projects. But very few applications have been received so far, and it needs help spreading the word. Please RT/boost and upvote it on HackerNews: news.ycombinator.com/item?id=4227... #foss #OpenSource #sustainability
floss.fund
Funding for Free and Open Source projects - FLOSS/fund
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Robert Fisher @fisherastro.bsky.social · 01/12/2024
Exciting to see so many new folks here. I’m a computational astrophysicist working to understand how dead cinders of stars can blow up and light up the sky in a last hurrah. We use big computers. (Figure below courtesy of current PhD student Vrutant Mehta and collaborator Ruediger Pakmor.)
Two plots, showing the density and the gradient of the velocity field of merging binary white dwarfs (top and bottom, respectively). Two detonations are seen in the lower, more massive white dwarfs.
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Robert Fisher @fisherastro.bsky.social · 26/11/2024
I wonder if @aip.bsky.social has statistics on this — both within the field and to other fields.
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Robert Fisher @fisherastro.bsky.social · 19/11/2024
This entire series is amazing! I think you’ve captured the spirit of the text — which aims for a very intuitive understanding of many complex topics with a minimum of technical detail (stuffed into a lot of appendices!) perfectly in digital form.
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Robert Fisher @fisherastro.bsky.social · 16/11/2024
Started using containers for a recent workshop presentation. Definitely will solve your dependency issues and also guarantee reproducibility (if done right) as a bonus.
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sanjana! @sanjanacurtis.bsky.social · 18/09/2024
Exciting news everyone! I am hiring a postdoc scholar to work with me at Oregon State Physics. If you love computational astrophysics, supernovae, and/or compact object mergers, this may be a great fit for you. More information here: aas.org/jobregister/...
aas.org
Postdoctoral Scholar in Theoretical and Computational Astrophysics | American Astronomical Society
The Department of Physics at Oregon State University invites applications for a 2 year postdoctoral scholar position. The successful candidate will work with Prof. Sanjana Curtis on multi-messenger as...
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Robert Fisher @fisherastro.bsky.social · 12/10/2024
Definitely! My favorite are seiches.
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Robert Fisher @fisherastro.bsky.social · 12/10/2024
What is your favorite wave phenomenon? 🙂
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Robert Fisher @fisherastro.bsky.social · 07/10/2024
@bot.astronomy.blue signup
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Robert Fisher @fisherastro.bsky.social · 06/10/2024
I participated in the judging of an elevator pitch competition hosted by our campus’s NSBE chapter. Every one of the participants deserves the opportunity to go to the national meeting to advance their career aspirations. Can you help make it happen? www.linkedin.com/posts/maxime...
linkedin.com
Maxime Larsen on LinkedIn: #nsbegold #nsbegold #nsbe
I just got asked a magical question! Why don't you bring every student from NSBE to the National Convention? I know the answer to this valid question but I…
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Robert Fisher @fisherastro.bsky.social · 22/09/2024
Necessary ingredients are all ready.
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Robert Fisher @fisherastro.bsky.social · 22/09/2024
The great astro Exodus from X took place early in Bluesky’s development, thanks to @astrokatie.com’s engagement. With X continuing to melt down, these numbers will only grow with time.
A virtual certificate with text "Celebrating 10M users on Bluesky, #83,849, Robert Fisher ‪@fisherastro.bsky.social‬, joined on May 20, 2023"
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Astronomer Royal for Scotland | Catherine Heymans @astroroyalscot.bsky.social · 29/07/2024
A calming happy astro #poem for the start of your week. I'm guessing John Updike wasn't aware of the blaze star though, a white dwarf that is currently busy cannibalising its neighbour, and about to explode, creating hellfire for a whole week! 🧪🔭 😱 ℹ️: www.astronomyedinburgh.org/2024/07/10/t...
White Dwarf

John Updike


   Welcome, welcome little star!
   I'm delighted that you are
   Up in heaven's vast extent
   No bigger than a continent.

   Relatively minuscule
   Spinning like a penny spoon
   Glinting like a polished spoon
   A kind of kindled demi-moon,

   You offer cheer to tiny Man
   'Mid galaxies Gargantuan --
   A little pill in endless night
   An antidote to cosmic fright.
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Robert Fisher @fisherastro.bsky.social · 02/07/2024
An impressive dialog! I suppose not many self-consistent infinite stacks of turtles happened to be in its training corpus. ♾️
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Robert Fisher @fisherastro.bsky.social · 02/07/2024
Genau.
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