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Rhys Taylor
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www.rhysy.net

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Ya done fucked up, Google

For me, Google+ is the internet. But it's clear that the security concern is a mere pretext for cancellation, so I don't have much hope of a revival.
https://www.blog.google/technology/safety-security/project-strobe/

As a just-in-case move that will take about five seconds of your time and cost you nothing, consider signing the petition :
https://www.change.org/p/google-inc-don-t-shut-down-google-plus-54f15bea-1d8c-4be9-a53f-e2ceee1302f4

My plan is to continue using G+ more or less as normal until the bitter end. I don't currently use any other social media but at some point - not anytime soon - I'll switch to something else, possibly multiple services. I haven't decided anything yet. There's a community dedicated to this here :
https://plus.google.com/communities/112164273001338979772

Feel free to note where you're going (or other ways I can reach you) in the comments on this thread, which I'll pin. Of course, I'll also be manually checking as many people as possible to see where y'all going. I can always be reached via my :
- Website : www.rhysy.net
- Blog : https://astrorhysy.blogspot.com/
- Email : feedback@rhysy.net

On the positive side this is an opportunity to start anew and form new bonds in new communities. On the negative side, G+ already had a fantastic community of people I never would have interacted with elsewhere. It was a great service, poorly understood and maintained by its own developers, kept alive by its wonderful users. Yes, even - especially - the crazy ones. Because while many of you antisocial media users have some views which are frankly worrying, not a single damn one of you didn't have at least something useful to say that I wouldn't have heard otherwise. Whatever's next, it won't be the same.
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Black Hole Ringworld

Imagine a ringworld built around a star. After eons of bliss, the star dies. Through the use of advanced technology, the ringworld itself survives intact, but the black hole remaining casts little light. In that late universe, the only remaining stars would be red dwarfs, so our advanced but dying civilization might move one (e.g. using a Shkadov thruster) to orbit the black hole itself, giving a hundred billion years of twilight.

This is what it would look like. Although I initially tried sketching out what I thought it looks like, I didn't feel confident in my intuition to give me an accurate result. Therefore, I wrote a raymarcher and had my computer do the heavy lifting. It turns out I actually got it mostly right, but the ease with which I could make modifications led me to change the viewpoint to this, much-more-cinematic, perspective. I then sketched that out in a quick colored-pencil drawing, producing this.

The black hole is a Kerr black hole (as most are), meaning it spins around its axis. You're looking down that axis, with the ringworld circling above and below. The red dwarf is orbiting very close to the event horizon and is being torn apart by tidal forces. You can see two main images of it, magnified (these also produce two faint lens flares, which you may be able to pick out). The black hole's frame-dragging twists the image of the ring around into a confusing shape and also Doppler-shifts it—the upper limb is bluer and the lower is redder.

Realism-wise, the black hole is probably much too large and therefore the effect far too dramatic. Also, although the geometry was calculated by a computer, and the light ray paths should be roughly correct, the relative distortion contribution of the spin vs. gravity, as well as the color, may be physically impossible (or not). Also, the system is gravitationally unstable (but ringworlds alone are gravitationally unstable and you weren't complaining about that).
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I don't get a paywall, so here's the new stuff :

Come 2012, a new team, led by Dr. Brendan Foley of Woods Hole Oceanographic Institution (and after 2017, Lund University), returned to the waters by Antikythera to relocate and resurvey the original wreck site, armed with the latest technologies. They found it, with its cargo scattered down a 55-meter downward slope, and also found the remains of a sixth person who had gone down with the ship.

Underwater archaeologists uncovered hundreds of artifacts, including two massive bronze spears, the life-size bronze representation of an arm, other pieces of marble and bronze statues, mosaic glassware, pieces of bone-inlaid furniture, blue game pawns, a sarcophagus lid, gold rings, and silver coins. They also found an encrusted, corroded disk, which was pulled from the seabed in 2017.

Like the original Antikythera Mechanism, after nearly 2,100 years underwater, the disk resembled greenish rock. About eight centimeters in diameter, the object still has four metal arms standing proud of the corners, with holes for pins. X-ray analysis shows the disk to bear the engraving of Taurus the bull.

It will be difficult to prove what exactly the Taurus disk is: part of the original Antikythera Mechanism, part of a second such mechanism, if one existed, or something else entirely. Based on the evidence so far, it looks exactly like other parts of the Mechanism, which had clearly been found incomplete. Based on the etching of the bull that can be seen with scanning, it may well be the gear that predicted the position of the zodiac constellation of Taurus.

Speaking of unsuspected technological prowess, recent X-ray imaging of a bronze statue discovered in the Antikythera wreck by Cousteau’s team in 1976 revealed a mechanical device inside its circular base, that apparently rotated the statue when a key was turned. This has yet to be confirmed. The statue dates from the second century B.C.E., contemporary or possibly older than the Antikythera Mechanisms. It could well be the earliest known example of a geared device.

While surveying the seabed, the divers found a second shipwreck, from about the same era. Like the first wreck, the second one is also scattered its bits and cargo down a steep slope, extending from 35 meters below sea level to more than 55m.

“We've only dedicated a couple of dives to investigation of this site, but what we've seen and recovered offers the possibility that the vessel sank in roughly the same time period as the Antikythera wreck," Foley said. "Comparing stamps on the handles of the Rhodian amphoras may help us narrow down the date of the sinking. Whether the two ships were associated directly is not yet known, and may never be known.”

As for the ship bearing the Mechanism, it had been a huge one, laden with precious cargo. It was a Greek grain ship from the Hellespont that was sailing for Italy, Foley avers, adding that the ship's planks are by far the biggest ever recovered from any other ancient shipwreck. "Even in their shrunken state, they are ten or eleven centimeters thick,” he says.

In fact, the only surviving comparable vessels are the "Nemi ships" that that the crazed Roman emperor Caligula had built as floating pleasure palaces in Lake Nemi the first century C.E. Two were discovered when Italian dictator Benito Mussolini had the lake drained in the 1930s and divers have since been searching for a possible third.

“These were pleasure barges with a shallow draft but were 70 to 80 meters long," says Foley. "I don’t think the ship that sank off Antikýthera was that long, but the planks on these floating pleasure platforms are smaller than on the Antikýthera shipwreck.”
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It will be interesting to see where this goes. Hopefully the peer-review process will ensure it doesn't become a free-for-all of every nutjob under the sun. There's not very much detail in the article, though there's a link to a 30 minute radio programme.

Academics who are frightened to explore controversial topics, in case it provokes a backlash, will soon have a safer route to publish such work. An international group of university researchers is planning a new journal which will allow articles on sensitive debates to be written under pseudonyms. They feel free intellectual discussion on tough issues is being hampered by a culture of fear and self-censorship. The Journal of Controversial Ideas will be launched early next year.

Prof McMahan stressed that the new cross-disciplinary publication will be fully peer-reviewed in line with normal academic standards. "The screening procedure will be as rigorous as those for other academic journals. The level of quality will be maintained," he said. He and his colleagues are establishing an intellectually diverse international editorial board with representation from the left and the right, as well as religious and secular thinkers, to ensure the journal is not identified with a specific viewpoint. They will soon issue a call for papers.

The Journal of Controversial Ideas will allow articles on sensitive debates to be written under pseudonyms.

Via Aerogramme Writers' Studio
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I never knew I needed a Jeff Bezos simulator before.
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I find this amusing to interpret literally. One can imagine the press conference :

"... and that's how we managed to make the mice transparent."
[Applause]
"Wonderful, professor. What about cats ?"
"Beg your pardon ?"
"You know, cats. Can this technique do cats as well ?"
"What ? Umm, no, sorry, just mice."
"What about chickens ?"
"No, only mice."
"Horses ?"
"Sorry, no, only mice for now."
"Surely this will work on dogs, though."
"Well...."
"Deer ? Ostriches ? Guinea fowl ?"
"Look, I'm sorry, but -"
"Are you really saying you've invented a technique that can turn mice transparent, but that's it ?"
[Embarrassed shuffling of feet]
".... yes."
"Well that seems awfully specific !"
"Look, I never said anything about guinea fowl or horses ! We only wanted to do mice ! Big mice ! Small mice ! Fat mice, skinny mice, fast mice, slow mice, any kind of mice you like ! Literally all of them ! Why can't you just be happy with the damn invisible mice ? How many times must I say it ? Isn't an invisible mouse impressive enough for you ? Honestly, I don't know why I bother."
"... I just wanted an invisible cat, is all."

Via +Ciro Villa.
A new technique that makes dead mice transparent and hard like plastic is giving researchers an unprecedented view of how different types of cell interact in the body. The approach lets scientists pinpoint specific tissues within an animal while scanning its entire body.
The technique, called vDISCO, has already revealed surprising structural connections between organs, including hints about the extent to which brain injuries affect the immune system and nerves in other parts of the body. That could lead to better treatments for traumatic brain injury or stroke.

Cai et al. (2018) Panoptic vDISCO imaging reveals neuronal connectivity, remote trauma effects and meningeal vessels in intact transparent mice: https://www.biorxiv.org/content/early/2018/07/23/374785
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A Gigantic Stealthy Dwarf With Lazy Stars

This really needs a press release when it's accepted for publication.

Astronomers love three-word acronyms, preferably containing the word "ultra" because it makes us feel ultra-important. Also we're hugely unimaginative at naming things, as the Very Large Array testifies. Anyway, while I'm especially interested in Ultra Diffuse Galaxies - big, fluffy star systems that may or may not be chock-full of dark matter - Ultra Faint Galaxies are interesting too. Not so much my speciality though, so bear that in mind.

Ultra Diffuse Galaxies are defined as having few stars per unit area. But because their total area can be very large, overall they can be quite "bright", at least in the sense of radiating lots of energy. Imagine if you could make a light that sent out the same total power of a floodlight but was ten metres on a side - close up, it'd look pretty dim to the eye, even though the total amount of energy per second was the same as a smaller floodlight.

Ultra Faint Galaxies, in contrast, are defined simply by the total amount of light they emit. They can be small and compact or big and fluffy.

This UFG is of the big and fluffy variety (not as big and fluffy as UDGs mind you). The paper is unusually thorough and complete, describing the discovery, follow-up observations, significance, and modelling. They even comment on the chemistry and possible gamma-ray emission of the object. And the icing on the cake is they actually manage to make the paper readable, so huge kudos to them for that.

While UDGs can be detected at large distances, UFGs are really only detectable in our Local Group. They're important because they might help understand the missing satellite problem (that models predict that we should find more small, nearby galaxies than we actually do) and also for studying galaxy dynamics. One such recent discovery (Crater II) was found to have unusually slow-moving stars, which, taken at face value, contradicts the standard model where galaxies are all dominated by massive dark matter halos - generally their stars are moving much more quickly.

It would be a mistake to think that Crater II is definitive evidence against the dark matter model though. While such an object is indeed compatible with alternative theories of gravity, it's also possible that it's simply lost much of its dark matter through tidal encounters. With pathetically small statistics, every object discovered in this class is significant.

That's where Antila 2 comes in. The authors discovered this using Gaia data. Gaia provides direct distance measurements to nearby stars but also proper motion (that's motion across the sky) data as well. In this case, it was by looking at the proper motions that the authors noticed a group of stars that hadn't been seen before. Gaia also makes this much easier in this region, where the density of stars, gas and dust towards the plane of the Galactic disc makes it difficult to spot anything at all. And by the standards of dwarf galaxies, Antila 2 is a biggie - much bigger than Crater II, and even comparable in size to the Large Magellanic Cloud (which has been known since prehistoric times). Only its incredible faintness - it's 4,000 times fainter than the LMC ! - and crowded location have kept it hidden for this long. That's no match for Gaia, however.

Antila 2 is also very cool. That is, like Crater II, its stars aren't moving very quickly. Unlike larger galaxies it doesn't seem to be rotating at all, the stars are just buzzing around randomly. That's not at all unusual for dwarf galaxies. What is unusual is that the stars only appear to be moving at around ~6 km/s, whereas for an object this size, ~20 km/s might be expected. Taken at face value, this would mean that Antila 2's dark matter halo has the lowest density of any such halo. So how could the stars end up being so dang lazy ? Is it a super-extreme object or did it start life as something more normal and have lethargy thrust upon it ?

There are several possibilities. One is that maybe the shape of the dark matter isn't typical. The usual assumption, based on models, is that dark matter halos have a central "cusp" (a horrible term we just have to live with), meaning a rapid increase in density in the centre. Antila 2 might instead have a "core" - a flatter density distribution in the centre. This could happen in two ways : 1) Early feedback (explosions and winds) by young stars could have removed so much gas that the sheer mass of the moving material could have disrupted the dark matter by its gravitational influence; 2) A tidal encounter with another galaxy (i.e. the Milky Way) could have stripped away much of its dark matter. In either case the end result is that there wouldn't be so much extra mass to accelerate the stars. Any stars which were moving too quickly would have been removed, and the pathetic remnant of the dark matter halo would only have been massive enough to hold on to the most sluggish.

The authors test these scenarios. Neither seems to work by itself, but together they might be able to do it. Thanks to the proper motion data of Gaia, they're able to work out the orbit of the galaxy so they can find out how close it's come to the Milky Way and thus they can estimate the tidal forces. Their initial conditions are necessarily a bit speculative but based on more typical dwarf galaxies. What seems to work is an initially cored dwarf (presumably formed via feedback) that then has a few disruptive orbits around the Milky Way.

There's some observational evidence to support this. Antila 2 appears to be stretched in its direction of motion, its chemical content appears unusual for its brightness (suggesting much of its original stellar content has been lost). On the other hand, the disruption ought to make the object more spherical than observed, but it's not certain if this is a crippling problem or not. Such an object would be able to survive for a few gigayears - long, but it probably implies it fell into the Milky Way's orbit much later than other satellites.

Overall, the conclusions are starkly different to the final sentence in the abstract saying this object may challenge the cold dark mater model, but that was the only inconsistency I spotted. They deserve a press release for this, I just hope it's as good as the paper. :)
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I'm a very recent convert to the Marvel movies (my single foray into superhero comic books was Deadpool; other than that I'm completely restricted to the movies). I just didn't enjoy the Spider-man films or some of the other earlier ones and I'm just generally biased against the superhero genre. I didn't see the point of giving people random magical abilities, especially since most of the time they all seemed to be mopey and depressed (Christopher Nolan's Batman films being an exception, where there was no magic and a very good need for the character to be mopey and depressed). I enjoyed the middle third of the first Thor film though, but found the other two thirds to be boring, pointless over-exaggerated melodrama.

Then, having nothing better to do at the time, I saw Guardians of the Galaxy 2, and I loved it. Here were a bunch of characters who were misfits, but not the classic uber-misanthropes that seem to dominate modern British sitcoms. They were, generally speaking, fundamentally happy about their existence. They enjoyed their abilities, for the most part. There was no needless angst, no pressing weight of boring responsibility, and it was very, very funny. The whole thing didn't take itself too seriously without sliding into farce. Since then I've been slowly but happily catching up on the large backlog of Marvel movies I'd unwisely dismissed as trite. Stan Lee seems like he was a thoroughly good egg.

Born in 1922 to poor working-class Jewish immigrants from Romania, Stanley Martin Lieber got a job in Timely Publications - that would eventually become Marvel Comics - a company owned by a relative. He was assigned to the comics division and - thanks to the reach of his imagination - rose to editor by the age of 18.

He was to become an icon of modern popular culture. Spidey, as he is affectionately known, had quite extraordinary powers - yet he had problems at work, at home and with his girlfriends. At last, the teenager was no longer just the sidekick, but the main hero. And the hero was no longer just brawn, he had brains too. "Just because he's a hero and has super powers doesn't mean he doesn't have problems," Stan Lee told the BBC.

The Hulk, The Mighty Thor, Iron Man and the rest all grappled with problems like drug abuse, bigotry and social inequality. Other superheroes broke new ground in other ways. Daredevil was blind, Black Panther was black and Silver Surfer pondered the state of humanity. Lee's influence remains. Some years ago the Marvel hero, Northstar, came out of the closet.

Radically, Lee gave the artists responsible for the comic designs credits for their work. Jack Kirby, Frank Miller, John Romitaand and others achieved cult status in their own right.
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