Keysh

20 ms·

1.
by Keysh 2y ago
The face-on galaxy image is credited to Stefan Payne-Wardenaar ( https://stefanpw.myportfolio.com/home ), whose Twitter and Bluesky bios say, "I make astronomy visualizations in Blender."
2.
by Keysh 2y ago
> is there some sort of gravitational body in the middle that makes everything orbit in galaxies? No. The Sun's orbit is determined by the total mass of stars, gas, and dark matter interior to the orbit. This is mostly due to the st
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by Keysh 2y ago
I think there is some, but it’s pretty limited. E.g., “He was an old man [who fished alone in a skiff in the Gulf Stream] and …”
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by Keysh 2y ago
"Keplerian" is a term of art based on the rotation curve in Newtonian gravity when all the mass of a system is concentrated at its center. For the Solar System, the rotation curve outside the radius of the Sun is pretty much pure
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by Keysh 2y ago
It's kind of amusing that you present "keplerian rotation curves" as a "prediction" of MOND, given that the whole point of MOND is a kludge to produce non -Keplerian rotation curves. That is, by definition MOND c
6.
by Keysh 2y ago
The "batting average" is a bit higher than that. For example, measurements of the proper motion (motion across the sky) of Sirius led to the prediction in 1844 that it was in an orbit with an (observed) faint or dark companion; th
7.
by Keysh 2y ago
You don't need a simulation; you just need an understanding of Newtonian gravity, basic algebra and a bit of calculus, and some knowledge of stellar masses, velocities, and space densities. This is a standard part of the grad school cu
8.
by Keysh 2y ago
The problem isn't so much the flatness of the rotation curve, but its continued high value: as you go farther and farther out in distance, it should drop rapidly because most of the visible matter is concentrated toward the center of
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by Keysh 2y ago
I think "if the training pool is large enough" is a real issue here. We're not talking about living languages with large, properly attested and annotated corpuses. Indeed, one of the thing you'd probably like the transla
10.
by Keysh 2y ago
It sounds like they were excavated in 1881-1882 (e.g., https://en.wikipedia.org/wiki/Sippar#Archaeology ) by Hormuzd Rassam ("widely believed to be the first-known Middle Eastern and Assyrian archaeologist from the
11.
by Keysh 2y ago
> there could be empty regions of space in which billions of years more have elapsed than in e.g. a galaxy. A problem with that idea would be that the ages of galaxies in low-density regions (including voids) tend to be younger than ga
12.
by Keysh 2y ago
> There have been a longstanding problem that the history of the universe and cosmological distance scale haven't made sense. https://medium.com/starts-with-a-bang/the-hubble-tension-sti ... > When I was gett
13.
by Keysh 2y ago
I like how the arXiv sub-category this paper is in is "Soft Condensed Matter". Because of course it is. (Also, the Acknowledgments ends with "We further thank [list of names] for their support and for eating up the sample lef
14.
by Keysh 2y ago
I'll admit I've never seen "track" used to mean "write" before.
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by Keysh 2y ago
> * I'd like to move the cursor backwards and forwards in long commands easier, maybe even with the mouse (!). Use case is, say, a long curl command and I press up-arrow to repeat it, but want to tweak something. So I press and hold
16.
by Keysh 2y ago
From Chapter VII of Thomas Kuhn, The Structure of Scientific Revolutions ( https://www.lri.fr/~mbl/Stanford/CS477/papers/Kuhn-SSR-2ndEd... ): "If awareness of anomaly plays a role in the emergence o
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by Keysh 2y ago
Physics has obviously had Kuhnian revolutions since Newton, the emergence of relativity and quantum mechanics being two obvious examples.
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by Keysh 2y ago
The Wikipedia entry includes notes on the hypothesized history of modifications to the disk. For example, the non-solar arcs were probably added later (different gold). So the original version had just the lunar crescent.
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by Keysh 2y ago
Not only that, Saxony-Anhalt filed a recent DMCA takedown notice against Wikimedia ( https://en.wikipedia.org/wiki/Nebra_sky_disc ): > In 2023, the state of Saxony-Anhalt filed a DMCA take down notice requesting remov
20.
by Keysh 2y ago
Tardigrades are not "extremophiles", which refers to organisms that live (grow, reproduce) in "extreme" environments ("phile" = "like, love"). Tardigrades can temporarily survive some rather extreme
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by Keysh 2y ago
Those would be "captive" ferrets, not "domesticated" ones. (They want to introduce the offspring from the breeding program into the wild, and have in fact done this for about 10,000 offspring.) This article in Science
22.
by Keysh 2y ago
From the linked Washington Post story: "The cloned animals were made by injecting one of Willa’s cells into an egg from a domesticated ferret." Which is kind of interesting, because domesticated ferrets are a different species.
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by Keysh 2y ago
The article says that it was no longer functional (in its communications abilities, at least) by that point > Launched in 1969 ... the spacecraft ceased working a few years later ... Also, what makes you think the US didn't already
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by Keysh 2y ago
The Tines in Vernor Vinge's A Fire Upon the Deep are pretty good example. (The aliens in A Deepness in the Sky are physically alien, but psychologically pretty close to humans.)
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by Keysh 2y ago
Amusingly, I have made three tries to read that book, and kept giving up (getting a little further each time). Partly it was the peculiar sense of aesthetics (e.g., the idea that of course audience would reject color movies) and partly it w
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by Keysh 2y ago
Do you recall the name of the good translator?
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by Keysh 2y ago
C.J. Cherryh's 1981 novel Wave Without a Shore has something vaguely similar, where the human inhabitants of a planet refuse to notice the non-human natives sharing their cities.
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by Keysh 2y ago
I remember reading this, and looking out my office window where the branches of neighboring tree (denuded of leaves because it was winter) made three or four near-perfect right angles in projection (along with intersections at other angles)
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by Keysh 2y ago
Ah, OK, thanks for the link.
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by Keysh 2y ago
> They arrayed three antennas together. No, they didn’t. The three antennas are in California, Spain, an Australia; they can’t all point at the same point in the sky at once, and even if two could do so, they’re not designed to work as a

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