<unnamed>

Public Key

npub166javys939pzl8unxz9j6rw2d7d3ffyrvnye59jquuxa0gyw508ss29nxq

Profile Code

nprofile1qqsddfwkzgzcjs30n7fnpzedph9xlxc55jpkfjv6zeqwwrwh5z828ncprpmhxue69uhhyetvv9ujumt0d4hhxarj9ecxjmnt9ev80z

Publishing to

relay.momostr.pink

Last Notes

2026-08-24 13:25:25 UTC

Does anyone have a ready made slide with all the arguments as to why AI sucks? (Looking for a backup slide in case someone asks a question about the no-AI sticker I have on some of my slides).

2026-08-15 18:23:41 UTC

My newest #woodworking project is done! Japanese style #Kumiko Lamp with Asanoha pattern. 312 pieces of ash and walnut. Each individually fitted.
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2026-08-07 10:55:35 UTC

I don’t referee for Elsevier for reasons people here probably know (they extract large amounts of money from science). But they still send me requests. They come from a no-reply email address. And I refuse to use the anonymous yes/no link because I can’t engage with them and let them know my reasons. So the request just sits there for a week or two until it times out. So, I’m sorry if your paper is held up because of that. Maybe submit elsewhere? 🤷‍♂️

2026-08-05 22:26:03 UTC

☀️🌑🌍 Just 6 days until the next total #solareclipse! Download my free, ad-free, and add-on-free "Solar Eclipse Live" app for iOS. It uses the #opensource tools REBOUND and ASSIST to calculate accurate ephemeris data on the fly without the need for an internet connection. So it's great if you plan to chase the totality in the middle of nowhere. And yeah, you really want to see totality if you can, as proven by this xkcd comic.
https://apps.apple.com/us/app/solar-eclipse-live/id6480014046
https://xkcd.com/2914/
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2026-07-27 20:06:19 UTC

I’ve seen this a few times now: someone vibe-codes something, doesn’t know enough to evaluate the code, and then has the audacity to email an expert to invite them to review the code for them. 😡

2026-06-29 15:56:02 UTC

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I grew up in Germany but now live in Canada. I was unfortunate enough to be back home during the heatwave for a visit. The non-AC culture is bizarre. If you want to safe energy great, just don't turn it down to freezing levels like they do in North America. But during a 40+ heatwave, it's really not about comfort but safety for a lot of people. (I wonder what will happen when they figure out that an AC is a heatpump.)

2026-06-08 18:17:14 UTC

RE: https://sueden.social/@me_/116715832898810488
When something is not available in the EU you probably don't want it anyway. Like chlorinated chicken, hormone-treated beef, large pickup trucks, and easily available firearms.
#note16s8…rrcu

2026-06-05 18:52:45 UTC

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3000kg, 800 m^2 😱

2026-06-05 18:24:06 UTC

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If I've read it correctly, they don't claim 0.0001 per satellite (that's the requirements). They claim "zero" because no components will enter with more than 15 Joules of energy. I smell BS.

2026-06-05 18:19:30 UTC

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Ok. I'll give it a go. Have you given interviews about SpaceX's reponse yet? Some of the claims are ridiculous, like the "zero" risk of causalities.
https://www.scribd.com/document/1045612919/SpaceX-Response-05-29-2026

2026-06-05 15:28:04 UTC

I got another interview request regarding SpaceX orbital data centres. Clearly this is just hype for the IPO. So I’m a bit conflicted about whether I should agree to the interview or not. I don’t have anything good to say about the idea, but at this moment any publicity seems like good publicity. Any thoughts @npub1dgc…cla4?

2026-06-03 20:25:17 UTC

Baby snapper 🐢 and its big brother. #algonquinpark #ontario
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2026-05-15 20:48:58 UTC

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I remember a discussion with Rashid Sunyaev at the IAS many years ago where he commented that the Hubble repair was so expensive that the government was keen on putting other satellites further away so that the scientists don’t get too comfortable with having serviceable satellites.

2026-04-18 14:44:04 UTC

#EnvironmentCanada is planning an update to their website. As anyone might guess, information density is down, contrast is down. Size is up from 350KB to 1.7MB. #enshittification
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2026-04-15 13:23:12 UTC

New long-read article about light pollution and overcrowding low Earth orbit with satellites:
"This will limit our access to space forever," says Hanno Rein.
https://www.cnet.com/science/space/features/satellite-overcrowding-space-junk-low-earth-orbit-starlink/

2026-03-30 20:00:17 UTC

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How can one possibly distinguish one from the other?

2026-03-30 19:35:02 UTC

I just gave an interview with a journalist raising concerns about Kessler Syndrom and complaining about megaconstellations in general. And less than 5 minutes later, I see a post about a starlink satellite being involved in a "fragment creation event".
@npub1dgc…cla4
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2026-03-27 23:47:00 UTC

Could someone please vibe-code a tool that monitors my keystrokes in vi and then suggest faster alternatives for the most common patterns?

2026-03-20 23:38:57 UTC

Over the years I've accumulated an inconsistent mess of integer types in REBOUND. I'm finally cleaning this up by using size_t for all array sizes and indices.

2026-03-17 14:22:27 UTC

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(We're close 😉)
https://files.mastodon.social/media_attachments/files/116/244/958/650/889/822/original/fb2a6dba16b0ec48.png

2026-03-17 14:21:15 UTC

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Congratulations!

2026-03-15 13:18:10 UTC

I'm one of two invited keynote speakers at SONAD 2026, the 41st Southern Ontario Numerical Analysis Day. It's a free one day event which this year takes place at the Department of Computer Science in Toronto on May 1st. If you're nearby and interested in numerical analysis and scientific computing, please sign up and join us!
https://www.cs.toronto.edu/~ccc/NAday26/
#hpc #toronto #computerscience

2026-01-13 22:57:47 UTC

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I guess the compiler assumed that because some random element somewhere in r is aligned, some other element in r should also be aligned. It then probably tried to optimizing the different "=NULL" assignments into one using a vector operation. But that failed because the first element in r never actually was properly aligned despite the attribute, and hence neither the other elements.

2026-01-13 22:38:24 UTC

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And of course, as soon as I post it, I find the problem. Despite me searching for an hour already...
The problem was an EXTRA aligned(64) attribute somewhere in the struct r.
I still don't understand the full reason for why this resulted in a segfault at the point it did. But fixing it is good enough for me right now...

2026-01-13 22:23:54 UTC

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FWIW, the code uses #AVX512 at other places in the code. That could be related (i.e. some alignment issue?). But I'm lost as how to find the right spot as the code the debuggers point to has no AVX512.

2026-01-13 22:21:53 UTC

Very frustrating bug:
Without optimization, everything runs fine. On O2 or higher, I get a segfault due to an invalid address 0x0. Same for both #clang and #gcc. And I cannot for the life of it figure out where this segfault originates. Both clang and gcc point to a line which doesn't make sense to me. For example in this code
r->a = NULL;
r->b = NULL;
r->c = NULL;
the last line triggers. According to the debugger r is not NULL.
Any suggestions welcome.

2026-01-09 02:05:32 UTC

A lot of my astronomy colleagues seem to be excited about a billionaire tech bro buying them a new space telescope to play with. I mean sure, better than spending the money on a deep-fake generating AI bot. But has anyone considered just taxing these people and then letting a democratically elected government decide what to do with all that abundant money?

2026-01-02 14:26:52 UTC

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It depends on the bear! ⬆️ is good advise for black bears.

2025-11-10 14:28:48 UTC

🎉💫 We had another paper accepted last week. @npub13t3…wxv7 was the lead on this one. We study the effect of a substellar flyby on the Solar System and find that there is a surprisingly high probability that such a flyby could have played an important role in shaping the system's architecture.
https://arxiv.org/abs/2412.04583
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2025-10-28 18:41:40 UTC

Today’s harvest: beets, kale, and almost 4kg of carrots.
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2025-10-22 20:12:23 UTC

@npub1dgc…cla4 😭 https://blogs.nvidia.com/blog/starcloud/?linkId=100000388085274

2025-09-10 15:02:01 UTC

My university now offers burner/loaner phones for people travelling to the US. Funny times.

2025-08-28 20:46:50 UTC

I'm working on an algorithm which can automatically determine the orbital hierarchy for an arbitrary set of point masses and then visualize it in a meaningful way. It's hard! Here's a working example of an octuple system made out of four equal mass circular binaries.
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2025-07-13 19:08:50 UTC

There's an article in the Guardian today about so many academic papers being published, it's hard to keep up. I completely agree!
“But nobody really knows what to do about it.”
How about a new journal where each author is only allowed to submit exactly one paper per year. I suspect it would lead to high quality papers because one has to be so selective.
Any thoughts? @npub1vfp…hct4 ?
https://www.theguardian.com/science/2025/jul/13/quality-of-scientific-papers-questioned-as-academics-overwhelmed-by-the-millions-published

2025-07-09 15:40:11 UTC

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💫🌎 My group's new paper is now on the arXiv. We do something really simple that I'm surprised nobody has done before: a convergence study of N-body simulations of the Solar System. We find that timesteps can be ridiculously large and still yield physical results. Specifically, the timestep can be as large as 1/3 of Mercury's orbital period, or ~32days. This works because the Solar System is chaotic and secular, not mean-motion resonances are driving the evolution. https://arxiv.org/abs/2507.04987

2025-07-04 14:16:57 UTC

🎉 Paper submitted!

2025-03-30 15:41:00 UTC

Ice storm #onstorm
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2025-03-25 21:55:05 UTC

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spf=pass, dkim=pass, dmarc=pass!

2025-03-25 21:37:15 UTC

TIL SPF, DKIM, and DMARC!

2025-03-17 00:58:24 UTC

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all you need is a Linux machine with a sound card and a microphone https://github.com/tphakala/birdnet-go

2025-03-17 00:33:06 UTC

Today’s bird detections in our backyard
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2025-01-31 22:28:48 UTC

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Side note: The servers use 240V. I didn't want to wait for the university to put a 240V circuit in at work and I don't have an easily accessible 240V socket at home either. So I built this MacGyver-style contraption which combines two 120V outlets on different circuits into one 240V. And yes, this is definitely not up to code for many different reasons and you should absolutely not try this at home yourself.
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2025-01-31 22:16:00 UTC

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The System Management Module (SMM) has its own ethernet port. I *think* I've successfully reset the SMM to factory defaults. However, the SMM's network port is completely silent - no traffic at all. Which I *think* is the default. There are instructions in the manual on how to enable the SMM network, but those require me to reach the XCC. So I'm a bit stuck. 🤷‍♂️
Any hints would be appreciated! 😉

2025-01-31 22:08:15 UTC

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So far I'm not having much luck in getting the nodes up and running. In short, I'm not sure how to access the Lenovo XClarity Controller (XCC). By default it is supposed to try DHCP first and then fallback to a static IP if that fails. I do see some traffic on the ethernet port, including a DHCP request, but strangely the DHCP offers are not accepted. The default static IP also doesn't work. So maybe the default behaviour was changed? It's not clear to me how to reset the XCC to factory defaults

2025-01-29 02:51:33 UTC

Many thanks to my (former) students [@zyrxvo](https://mas.to/@zyrxvo ), Dang, Pejvak and Nick, who helped disassemble 16 nodes of the NIAGARA supercomputer today. Everything is now at UTSC and once we've put it back together, my group will have its own small compute cluster with 640 cores.
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2024-12-22 16:04:35 UTC

This is pretty cool: Amateur astronomers* were able to receive the carrier signal of Voyager 1. https://www.camras.nl/en/blog/2024/dwingeloo-telescope-receives-signals-from-voyager-1/
* Amateur astronomers who have access to a 25m antenna.
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2024-12-02 22:41:48 UTC

PSA: If you're a scientist and use an LLM for your research, then I don't think very highly of you.

2024-11-30 22:00:14 UTC

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I've finished the bedside tables! #woodworking
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2024-11-24 20:27:59 UTC

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I made good progress on the bedside tables this weekend. #woodworking

2024-11-16 22:30:31 UTC

Upcoming #woodworking project: two bedside tables. Still trying to fine tune the design...
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2024-11-15 12:51:41 UTC

☄️+⭐️=💥 My student Dang Pham together with Matthew Hopkins in Oxford led a project about fast radio bursts (FRBs) and interstellar objects (ISOs). In short: ISOs colliding with neutron stars could actually explain the observed FRB rate, the observed energy distribution, and even even some of the sub-structure. The paper has been accepted and is now on the arXiv. Check it out!
https://arxiv.org/abs/2411.09135
#astrodon #astronomy #astrophysics

2024-11-11 17:48:36 UTC

I'm teaching a graduate course on visualizations and #GPU programming this term. This week we'll write an N-body integrator using #WebGPU! #astrodon
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2024-11-02 14:57:00 UTC

Small #woodworking project: laminated and framed a map of #AlgonquinPark to keep track of our trips.
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