The dust clouds around supermassive black holes are the perfect breeding ground for an exotic new type of planet.
Blanets are fundamentally similar to planets; they have enough mass to be rounded by their own gravity, but are not massive enough to start thermonuclear fusion, just like planets that orbit stars. In 2019, a team of astronomers and exoplanetologists showed that there is a safe zone around a supermassive black hole that could harbor thousands of blanets in orbit around it.
The generally agreed theory of planet formation is that it occurs in the protoplanetary disk of gas and dust around young stars. When dust particles collide, they stick together to form larger clumps that sweep up more dust as they orbit the star. Eventually, these clumps grow large enough to become planets.
A similar process should occur around supermassive black holes. These are surrounded by huge clouds of dust and gas that bear some similarities to the protoplanetary disks around young stars. As the cloud orbits the black hole, dust particles should collide and stick together forming larger clumps that eventually become blanets.
The scale of this process is vast compared to conventional planet formation. Supermassive black holes are huge, at least a hundred thousand times the mass of our Sun. But ice particles can only form where it is cool enough for volatile compounds to condense.
This turns out to be around 100 trillion kilometers from the black hole itself, in an orbit that takes about a million years to complete. Birthdays on blanets would be few and far between!
An important limitation is the relative velocity of the dust particles in the cloud. Slow moving particles can collide and stick together, but fast-moving ones would constantly break apart in high-speed collisions. Wada and co calculated that this critical velocity must be less than about 80 meters per second.
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Seeing the world from under ! 🐠🐠🐠💦🌊 | benthouard
Location: French Polynesia
British artist Jason Anderson creates colorful abstract paintings composed of pixelated swatches of pastel-toned oil paint. Up-close, the artist’s paintings look like blocky layers of shapes and color; but, from afar, his scenes—featuring cityscapes, roads, trains, and marinas—are revealed.
Anderson began his career as a stained glass apprentice, where he worked on restoring the windows of cathedrals. He soon progressed onto designing the glass murals himself, where he learned how to break down subject matter into “jigsaws” of colored sections. This approach still shines through in his paintings today—complex scenes are brought to life with simple shapes and careful consideration to hue and tone.
Mars
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Hi! Can you tell some uni or colleges math resources?
Can you be more specific? Like resources for studying for particular undergrad level classes?
A few “classic” online references:
Paul’s online math notes (https://tutorial.math.lamar.edu/): algebra, calc 1-3, diff eqs though I’ve mostly only used the calc ones. A common favorite
Khan Academy: haven’t actually used any of their math stuff for years but I remember their videos were good
3blue1brown: he has a series on calc, diff eqs, and linear alg. I haven’t actually watched many of these either but his videos are generally good and I know people who like the series in particular
If you mean higher level math, I tend to just use a search engine and end up referencing a mix of wikipedia, wolfram mathworld, random pdfs from various universities, and math stack exchange. And of course textbook pdfs
If you give me more details, I’ll see if I can think of anything else!
This is the Mesha Stele. Written around 850 BCE, it was commissioned by King Mesha of Moab, a small nation around what is today Jordan. The basalt stele describes how Chemosh, the god of Moab, had previously been angry with his people and had allowed them to be subjugated to Israel but he eventually returned to his people and helped them gain their freedom from Israel. The stone then details King Mesha’s building projects.
The Mesha Stele roughly agrees with the Israelites version of events in the Books of Kings (2 Kings 3:4–8). Which makes it really, really important historically. The stele is also the most extensive inscription ever recovered that refers to the kingdom of Israel and it bears the earliest certain reference to the Israelite god Yahweh outside of the Bible itself.
the most beautiful words in the english language
ineffable — indescribable, unspeakable
eudaemonia — the state of consummate happiness
sumptuous — extremely costly, luxurious, magnificent
nadir — the lowest point (of something abstract)
lassitude —tiredness, lack of energy
scintilla — a spark or a trace of something
aurora — the dawn
quintessential — perfectly typical or representative of a particular kind of person or thing
renaissance — revival
bodacious — remarkable, admirable
ebullience — the quality of excitement and enthusiasm