Guillaume 🦗 @guillaume@aleph.land
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Into science/technology/some math. I think what really matters is reducing suffering for all sentient beings.
Joined Jan 2019
Guillaume 🦗
boosted
♲ @diane_a@pluspora.com:
❝Since her death in 1979, the woman who discovered what the universe is made of has not so much as received a memorial plaque. Her newspaper obituaries do not mention her greatest discovery. […] Every high school student knows that Isaac Newton discovered gravity, that Charles Darwin discovered evolution, and that Albert Einstein discovered the relativity of time. But when it comes to the composition of our universe, the textbooks simply say that the most abundant atom in the universe is hydrogen. And no one ever wonders how we know.❞ — Jeremy Knowles, discussing the complete lack of recognition Cecilia Payne gets, even today, for her revolutionary discovery. (via alliterate)
OH WAIT LET ME TELL YOU ABOUT CECILIA PAYNE
• Cecilia Payne won a scholarship to Cambridge.
• Cecilia Payne completed her studies, but Cambridge wouldn’t give her a degree because she was a woman, so she said to heck with that and moved to the United States to work at Harvard.
• Cecilia Payne was the first person ever to earn a Ph.D. in astronomy from Radcliffe College, with what Otto Strauve called “the most brilliant Ph.D. thesis ever written in astronomy.”
• Not only did Cecilia Payne discover what the universe is made of, she also discovered what the sun is made of (Henry Norris Russell, a fellow astronomer, is usually given credit for discovering that the sun’s composition is different from the Earth’s, but he came to his conclusions four years later than Payne — after telling her not to publish).
• Cecilia Payne is the reason we know basically anything about variable stars (stars whose brightness as seen from earth fluctuates). Literally every other study on variable stars is based on her work.
• Cecilia Payne was the first woman to be promoted to full professor from within Harvard and the first woman to head a science department at Harvard. She also inspired entire generations of women to take up science.
• Cecilia Payne is awesome and everyone should know her.
Who ever thought that "¤¶¦" were more important than "…"? Or that anyone needed "©" *twice* on their keyboard?
My keymap is supposed to have an ellipsis on J with altgr but all I can get is ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉
Guillaume 🦗
boosted
boost if you're french or you hate the french
Guillaume 🦗
boosted
job search, repeats appreciated
Also sorry for my weird use of #hashtags, I'm too old and don't understand how they work 😅
The #solarfoods concept sounds like a really good idea: turning CO2 into #food, including protein, using electricity instead of plants.
Surprisingly, I think it makes a lot of sense from an energy perspective. #Photosynthesis is much less efficient than #solar cells, so we can save a lot of resources that way! It's totally different from using solar panels to generate artificial light to then use for growing plants, which turns light into other types of energy twice and compounds the inefficiencies of both solar cells and photosynthesis.
It also disconnects food production from ethical problems related to #agriculture, like the suffering of trillions of #insects killed with #pesticides. (A lot on insects also suffer in "natural" environments from non-anthropic causes, but this problem can probably be treated separately).
So yesterday I rediscovered the #blog https://eukaryotewritesblog.com/ that I had forgotten for too long. It's really good.
I also love the name of the blog, and one of the things that stop me from starting my own is that I can't find a clever domain name.
How do people read #blogs? There are so many of them…
The various Fourier transforms are also exact representations of signals. The (complex) frequency content of a signal contains *exactly* the same information as the temporal content. It can be seen as an isometry in a vector space (a bit like a rotation but in potentially very high dimensions).
This video on digital sampling is still extremely relevant: https://www.xiph.org/video/vid2.shtml
I again saw a video today claiming that the quality of a digital signal degrades as you approach the Nyquist frequency (half of the sampling frequency). No. That's just not true. A band limited signal, containing information of to a frequency f, can be captured *exactly* by sampling it at any frequency larger than 2f. If you sample a band-limited signal according to this limit and then pass it through a digital to analogue converter you get *exactly the same thing* as you started with. Even if it contains data at 22 kHz and you sample it at 44.1 kHz. (But you really want it to contain nothing above 22.05 kHz or it will be aliased and you will definitely lose data).
Interesting, the Swedish TV is interviewing someone who knows math and explains that masks are useful?!
https://www.svt.se/nyheter/inrikes/matematikern-det-hander-om-alla-bar-munskydd
Guillaume 🦗
boosted
Guillaume 🦗
boosted
#TIL how Fourier transforms and #pseudospectral methods are intimately related to #FEM. What was missing from the picture is how a tool for numerical integration could be used for numerical differentiation.
If you think about it, Fourier transforms are also expressed as integration over an interval in space. When you differentiate a function it only affects the basis. For example:
exp(ikx) -> ik * exp(ikx)
1/2
Oops, 430 tabs open. I should tidy a bit.
It's a Heisenbug: it only appears when running a massively parallel simulation, and when debugging on a large memory node with "only" 72 cores everything is fine.
It's not the first time I encounter this kind of behaviour, I think there is an easy way to bypass the problem (not fix the bug).
That's it, I'm done. I add some forcing to my simulation in once place. I test it, it works fine, but then this appears in a totally different place. I must have corrupted some array somewhere, it's going to be fun to debug.
(Of course I only notice that something looks slightly wrong after running for several thousands of core-hours, because it's easy to miss if you don't look at the right place.).
Just sharing this:
Fully funded PhD: Assessing effects of urbanization and artificial light on birds' welfare, University of Glasgow
Guillaume 🦗
boosted
Do you consume oat drink, soy yoghurt, or other #vegan dairy alternatives?
EU parliament is attempting to ban any terms, marketing, or even appearance of vegan products that are associated to milk or dairy. This includes the terms "yoghurt" style, similar packaging in cartons or yoghurt cups, or even the comparison with milk's climate impact.
While this dairy-lobby-driven amendment is already through parliament, there's a petition to stop it in council. https://stopam171.com/
- blog
- hopefully one day
- languages
- 🇫🇷 / 🇬🇧 / learning 🇸🇪
Into science/technology/some math. I think what really matters is reducing suffering for all sentient beings.
Joined Jan 2019
