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Keyshon Dark Matter: The Situation Has Changed

I kind of assumed that a YouTube video on that subject would be a waste of time, and boy was it. That was amazingly ignorant.

Galaxies are often isolated. They come in clusters, and also in groups, and in isolation (including isolated galaxies inside cosmic voids). The isolated galaxies have the same "dark matter" phenomena as galaxies in clusters (which, by the way, do not have perfectly circular orbits, just to start with).

Keyshon Dark Matter: The Situation Has Changed

This seems to suffer from the usual problem of non-astronomers not understanding the breadth of the problem they think they're trying to solve. That is, they've vaguely heard that the problem is in the rotation of disk galaxies, and so they propose solutions that depend on the rotation (and maybe also on the flattening).

But the "dark matter" problem occurs for basically all galaxies, including things like elliptical and dwarf spheroidal galaxies that have no bulk rotation at all. (And also disk galaxies where a significant fraction of the stars and gas are counter-rotating.) The same applies to groups and clusters of galaxies.

Keyshon Dark Matter: The Situation Has Changed

That's not how epicycles were used. Ptolemy set up the standard geocentric model with epicycles (and deferents and equants), and these were used more or less unchanged for over a thousand years. When, in the late medieval period, some Arab astronomers began tinkering with modifications, these were motivated by a desire for better agreement with the Aristotelian ideal of uniform circular motion (i.e., to somehow replace Ptolemy's non-uniform equant device with some combination of uniform circular motion), not any desire to match the measurements better.

Keyshon Stars that race through space at nearly the speed of light

"Chinese astronomers recently published research on 591 high-velocity stars in our galaxy [2, 3], and 43 of these were hypervelocity stars, moving at relativistic speeds and destined to eventually escape the Milky Way entirely."

All of those stars have velocities < 1000 km/s relative to the Milky Way, which is less than 1/3 of one percent of the speed of light. Calling that "relativistic" is just hyperbole.

Keyshon Ingenuity: NASA's Mars helicopter makes it three from three

No; that’s a potential use of upgraded, more capable rotorcraft in future missions.

Keyshon 2.5B T. rex inhabited the planet, researchers say

Many dinosaurs were warm-blooded; fossils of dinosaurs have been found in Antarctica (granted, that’s from a time when the global climate was warmer and Antarctica was ice-free, but still...).

Keyshon Misunderstanding Malthus’ mistake

I think that's perhaps rather generically true for premodern times. I've seen estimates of mortality rates for medieval England that have cities consistently higher than rural areas, so you'd have to have migration to the cities.

Keyshon Misunderstanding Malthus’ mistake

> until the 20th century, with Beijing* as the primary exception, big cities were in Western Asia, North Africa, and Europe > Why did rice-growing areas have villages while wheat areas developed cities?

I'm sorry but that's simply untrue. There were lots of cities in premodern China. Urbanization probably got started earlier in the Near East, which is why you get early large cities there, but even in the list you link to, from ca. 1000 BC on there are basically always one or more Chinese cities in the list: Haojing, Luoyan, Xiadu, Chang'an/Xian, Nanjing, Kaifeng, Hangzou, .... (And this is ignoring other large cities that were never the largest like Guangzhou.)

(Beijing doesn't become really significant until the Mongol Yuan dynasty makes it their capital in the 13th Century.)

Keyshon Gigantic jet spied from black hole in early universe

Yes, exactly.

(The Triangulum Galaxy, M33, can sometimes be seen; at ~ 3 million light years, it’s further away and thus an even older “snapshot” than Andromeda.)

Keyshon Gigantic jet spied from black hole in early universe

I’ve seen it from fairly high in the Sierra Nevadas, far from any cities, and I still think it’s very faint.

Keyshon Gigantic jet spied from black hole in early universe

To be a bit pedantic: that’s only true for the Andromeda Galaxy (distance ~ 2,4 million light years), which is very hard to see with the naked eye. The Large and Small Magellanic Clouds are easy to see (from the Southern Hemisphere), but are only about 150,000-200,000 light years away.

Keyshon Gigantic jet spied from black hole in early universe

If the jet only turned on a finite time ago, then it will only have gotten so far in that time, so it will have a length = (jet velocity) * (time jet has been active).

Keyshon Astronomer Avi Loeb Says Aliens Have Visited, and He’s Not Kidding

I think you need to take what Loeb is saying with a very large grain of salt. There's a fair amount of annoyance and disgust within the astronomical community at his misrepresentation of what other astronomers have or have not been doing, particularly given that he's only been interested in this for a handful of years, versus the decades others have devoted to it.

There's a large degree of self-congratulation and self-promotion in what Loeb is saying, and denigration of what others have been doing. The idea that this field of research is "stifled" because people are "scared" is basically bullshit.

Keyshon ‘Seven Sisters’ Myths May Reach Back 100k Years

The land bridge connected Australia to New Guinea and the eastern parts of Indonesia, not to India. No one has any idea what the precise relation of Australian languages to any other set of human languages is.

Keyshon ‘Seven Sisters’ Myths May Reach Back 100k Years

There are, even today, languages that lack words for numbers higher than 2, 3, or 4 -- including a number of Australian languages. This tends to be more true for languages of contemporary hunter-gatherer. (See, e.g., Caleb Everett's Numbers and the Making of Us: Counting and the Course of Human Culture and references therein, or this article: https://theconversation.com/anumeric-people-what-happens-whe...). Studies of people who are native speakers of such languages actually do have difficulties keeping precise track of different numbers of items, at least at the level of five or more.

(There are Australian languages with more extensive number words, which is probably where the examples of "Pleiades = 7 women" stories come from.)

Keyshon ‘Seven Sisters’ Myths May Reach Back 100k Years

A third possibility is one of the stars used to be much brighter for whatever reason.

This is an idea that's been tossed around for a while; it has the problem that ancient Greek discussions agree that there were only six stars visible as long as anyone can recall -- even though the myth said there were seven. So if there was a faded star, it faded prior to 500 BC. (Also, no good candidates for a faded star from modern astronomical studies of the Pleiades.)

Ancient drawings would help locate the 7th star.

Rappenglück (1997) suggested that a collection of dots in the Lascaux cave paintings might represent the Pleiades, in part because it's located above the shoulder of an aurochs (i.e., like the Pleiades is located relative to the constellation of Taurus). But there are only six dots.

Keyshon New measurements of the sky's blackness

No, because only about 10% of normal (baryonic) matter is actually in the form of stars. The rest is mostly in the form of hot, dilute gas in intergalactic space.

The idea that about 5% of the total mass-energy budget of the universe is in the form of baryonic matter is well-determined by cosmological observations (including the relative amounts of hydrogen and helium formed in the Big Bang). It if turns out we've overestimated the amount of baryonic matter in stars by a factor of two, that just means that 95% of the baryons are in the hot intergalactic medium instead of 90%.

Keyshon The Weakness of Anthropic Arguments

Well, nor can Occam's Razor, but we don't seem to have a problem quoting that!

Occam's Razor is not an argument or explanation. It's a heuristic for discriminating among different arguments/explanations.

And anthropic arguments amount to "there isn't any explanation for the precise value of the fine structure constant!" Or "you should just give up trying to explain why it has the value it has!"

Keyshon In the animal kingdom, the astonishing power of the number instinct

The bee paper referenced in the original article (Dacke & Srinivasan 2008) is about real bees, and does a pretty good job of showing that the bees must somehow be keeping numerical track of how many instances of a particular landmark they've passed, at least up to a total of four.

Keyshon Missions to and Sample Returns from Nearby Interstellar Objects

Not really, because "missions without sample returns" (aka "flyby/impactor") is one of the options considered.

Keyshon Fastest star ever seen is moving at 8% the speed of light

No one in astronomy uses TIFFs. Most scientific images are stored in FITS format, either in integer form for some raw data or in floating-point form.

Keyshon Novelty and Heresy

"it took another 200 years to detect parallax"

However, the aberration of starlight was detected in the early 1700s. Although no one had thought to predict its appearance, people quickly realized it only made sense if the Earth was in motion, and was impossible to produce in a geocentric model.

(And, of course, heliocentric elliptical orbits of Kepler explained planetary motion much better than any geocentric system.)

Keyshon Novelty and Heresy

And what observations were these?

(And I wish you'd stop this nonsense of implying that Galileo had his own special heliocentric model. He didn't; he was advocating the model of Copernicus.)

Keyshon Novelty and Heresy

That would be difficult, since it isn't true. The Church had banned Copernicus's book and the general concept of heliocentrism in 1616, which was a full 16 years before they went after Galileo for promoting heliocentrism.

Keyshon Where Is the Sun Located in the Milky Way?

No, it is pretty random, just as the orbits of binary stars are randomly oriented. The scales of star and solar-system formation are much, much smaller than the scale of the galaxy, so the memory of the latter has been scrambled by all the intermediate and local processes.

From this Cornell "Ask an Astronomer" page (http://curious.astro.cornell.edu/about-us/159-our-solar-syst...)

"The size of a solar system is so much smaller than the size of the Galaxy, that the Galaxy's structure has no impact on the orientation of a solar system. What determines their orientations is the direction of the angular momentum that the system had when it formed, and that's pretty much random."

Or take a look at these ALMA images of protoplanetary disks (solar systems in the making) around pre-main-sequence stars. All are at very similar distances, and most are at very similar positions relative to the Galactic plane, so they should all show very similar projected shapes and orientations if they followed the galaxy's orientation -- but they are all over the place.

https://www.eso.org/public/images/potw1904a/

Keyshon Where Is the Sun Located in the Milky Way?

The period of the vertical orbit is closer to 1/3 that of the planar orbit: roughly 70 million years, versus about 225 million years for the azimuthal ("horizontal") period. Since the periods aren't in an integer ratio (and you wouldn't generally expect them to be for galactic orbits), it's also not neatly closed like the schematic suggests.

Keyshon Where Is the Sun Located in the Milky Way?

It's basically random; the rotation of a solar system depends on the rotation of the gas clump that collapses to form the star and its system, and that depends on local details about the relative orientation of local gas clumps, the possible influence of winds from nearby massive stars and supernova shock waves, and general turbulent motions within molecular clouds.

Keyshon Where Is the Sun Located in the Milky Way?

We don't define galaxies in general to spin in the opposite direction.

Just the Milky Way.

(The reason for this seems to be that Galactic "North" was defined long before we had the data to determine which way the Milky Way rotated -- or even that it rotated. By the time the rotation was definitively determined, it was too late to override convention. This may go back to William Herschel deciding that the "north pole" of the Galaxy should be in the same hemisphere of the sky that the Earth's north pole pointed toward. In retrospect, he had a 50% chance of being right...)

Keyshon Great apes appear to have “theory of mind”

> Multiple hominid species on Earth have had a technology gap on an unfathomable timescale. Indeed, the Denisovans developed stone tools tens of thousands of years before our own species.

Nonsense. Hominin toolmaking and tool use go back more than 2 million years, long before the last common ancestor of humans and the Neanderthal/Denisovan branch. About all we can say about Denisovan tool use is that their technology, circa 100,000 or 150,000 years ago, was roughly the same as contemporary Neanderthal and human technology.

Keyshon The End of the Roman Empire Wasn’t That Bad

That the church rejected heliocentrism because it clashed with scripture is a common misinterpretation.

No, it's the simple truth, as the Church and other documents from the time attest.

Galileo's model did not match the observations of the time

Galileo did not have his own model of the heavens; he was a proponent of Copernicus's heliocentric model, which gave predictions approximately as accurate (or inaccurate) as those of the Ptolemaic model. Galileo's observations of the phases of Venus, however, did render the Ptolemaic model untenable, as most astronomers admitted once they had confirmed Galileo's observations themselves. After that, the debate was between heliocentrism and various neo-geocentric models, like Tycho Brahe's.

Galileo may well have offended the Pope with the character of Simplicius, but that character appeared in the book Dialog Concerning the Two World Systems, which was published in 1632. Copernicus's De Revolutionibus was placed on the Index of Prohibited Books, along with other heliocentric texts, 16 years earlier, in 1616. (This was also the time of the Inquisition's first investigation of Galileo, for promulgating doctrines contrary to scripture.)

The official Church decree of 5 March 1616 read, in part: "This Holy Congregation has also learned about the spreading and acceptance by many of the false Pythagorean doctrine, altogether contrary to the Holy Scripture, that the earth moves and the sun is motionless, which is also taught by Nicholaus Copernicus's On the Revolutions of the Heavenly Spheres and by Diego de Zuñiga's On Job. This may be seen from a certain letter published by a certain Carmelite Father, whose title is Letter of the Reverend Father Paolo Foscarini, on the Pythagorean and Copernican Opinion of the Earth's Motion and Sun's Rest and on the New Pythagorean World System (Naples: Lazzaro Scoriggio, 1615), in which the said Father tries to show that the above-mentioned doctrine of the sun's rest at the center of the world and the earth's motion is consonant with the truth and does not contradict Holy Scripture. Therefore, in order that this opinion may not creep any further to the prejudice of Catholic truth, the Congregation has decided that the books by Nicolaus Copernicus (On the Revolutions of the Heavenly Spheres) and Diego de Zuñiga (On Job) be suspended until corrected; but that the book of the Carmelite Father Paolo Antonio Foscarini be completely prohibited and condemned; and that all other books which teach the same be likewise prohibited..."

("Corrected" in this case means with their heliocentric content censored.)

See the following for more of the background: http://copernicus.torun.pl/en/revolution/reception/2/ https://ui.adsabs.harvard.edu/abs/1989JHA....20....1W/abstra...