Thursday, May 12, 2022
The Milky Way’s Black Hole Comes to Light - The New York Times
The Milky Way’s Black Hole Comes to Light
"The Event Horizon Telescope has once again caught sight of the “unseeable.”
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Astronomers announced on Thursday that they had pierced the veil of darkness and dust at the center of our Milky Way galaxy to capture the first picture of “the gentle giant” dwelling there: a supermassive black hole, a trapdoor in space-time through which the equivalent of four million suns have been dispatched to eternity, leaving behind only their gravity and violently bent space-time.
The image, released in six simultaneous news conferences in Washington, and around the globe, showed a lumpy doughnut of radio emission framing empty space. Oohs and aahs broke out at the National Press Club in Washington when Feryal Ozel of the University of Arizona displayed what she called “the first direct image of the gentle giant in the center of our galaxy.” She added: “It seems that black holes like doughnuts.”
Dr. Ozel is part of the Event Horizon Telescope project, a collaboration of more than 300 scientists from 13 institutions that operates an ever-growing global network of telescopes to compose one large telescope as big as Earth.
The team’s results are being published today in The Astrophysical Journal Letters.
The new image joins the first ever picture of a black hole, in the galaxy Messier 87, or M87, which the same team of researchers produced in 2019. “We have seen what we thought was ‘unseeable,’” Sheperd Doeleman, an astronomer at the Harvard-Smithsonian Center for Astrophysics, said at the time.
The similarity in the pictures demonstrated that the 2019 image was not a coincidence, Dr. Ozel said.
Moreover, the features of the radio doughnut matched perfectly with predictions derived from the motions of stars and gas clouds around the galactic center. “This is an extraordinary verification of Einstein’s general theory of relativity,” said Michael Johnson, a team member and also of the Harvard-Smithsonian Center.
Einstein’s bad dream
Black holes were an unwelcome consequence of Albert Einstein’s general theory of relativity, which attributed gravity to the warping of space and time by matter and energy, much as how a mattress sags under a sleeper.
Einstein’s insight led to a new conception of the cosmos, in which space-time could quiver, bend, rip, expand, swirl and even disappear forever into the maw of a black hole, an entity with gravity so strong that not even light could escape it.
Einstein disapproved of this idea, but the universe is now known to be speckled with black holes. Many are the remains of dead stars that collapsed inward on themselves and just kept going.
But there seems to be a black hole at the center of nearly every galaxy, ours included, that can be millions or billions of times as massive as our sun. Astronomers still do not understand how these supermassive black holes have grown so big.
Paradoxically, despite their ability to swallow light, black holes are the most luminous objects in the universe. Materials — gas, dust, shredded stars — that fall into a black hole are heated to millions of degrees in a dense maelstrom of electromagnetic fields. Most of that matter falls into the black hole, but some is squirted out by enormous pressures and magnetic fields.
Such fireworks, which can outshine galaxies by a thousandfold, can be seen across the universe; when first observed in the early 1960s, they were called quasars. Their discovery led physicists and astronomers to take seriously the notion that black holes existed.
What gave rise to such behemoths of nothingness is a mystery. Dense wrinkles in the primordial energies of the Big Bang? Monster runaway stars that collapsed and consumed their surroundings in the dawning years of the universe?
The center of the Milky Way coincides with a faint source of radio noise called Sagittarius A* (pronounced Sagittarius A-star). Astronomers including Andrea Ghez of the University of California, Los Angeles and Reinhard Genzel of the Max Planck Institute for Extraterrestrial Physics had calculated that whatever was there had the mass of 4.14 million suns. They reached that estimate by tracking the orbits of stars and gas clouds swirling about the center of the Milky Way and measuring their velocities at one-third the speed of light. For their achievement, Dr. Genzel and Dr. Ghez won the Nobel Prize in Physics in 2020.
If it was not a black hole, neither Einstein nor anyone else knew what it could be.
Chasing a shadow
Proving that it was a black hole was another job entirely.
According to research that goes back to a 1967 paper by the physicist James Bardeen, the Sagittarius black hole, if it were there, would appear as a ghostly dark circle amid a haze of radio waves. At 50 million miles across, this hollow shadow would appear about as big from Earth as an orange on the moon.
Astronomers have been trying to sharpen the acuity of their telescopes to resolve the shadow of that orange. But ionized electrons and protons in interstellar space scatter the radio waves into a blur that obscures details of the source. “It’s like looking through shower glass,” Dr. Doeleman said recently.
To see deeper into the black hole shadow, researchers needed to be able to tune their radio telescopes to shorter wavelengths that could penetrate the haze. And they needed a bigger telescope.
In 2009, Dr. Doeleman and his colleagues formed the Event Horizon Telescope. Today, the collaborative project employs 11 different radio telescopes around the world.
The telescope is named after the point of no return around a black hole. The team scored its first triumph in April 2019, when it presented a picture of the M87 black hole. In 2021, team members refined their data to reveal magnetic fields swirling around the black hole like a finely grooved rifle barrel pumping matter and energy into the void.
The data for Sagittarius A* were recorded during the same observing run in 2017 that produced the M87 image, but with more antennas — eight instead of seven — because the team was able to include a South Pole telescope that could not see M87.
Sagittarius A*, the black hole in the Milky Way galaxy, was a harder target. It is less than one-thousandth the mass and size of the M87 hole and, therefore, evolves a thousand times faster. The M87 black hole barely budges during a weeklong observing run, but Sagittarius A* changes its appearance as often as every five minutes, “burbling and gurgling” in the words of Dr. Ozel.
Dr. Doeleman said, “The key thing is that, for M87, after a week of observing, it’s hardly budged.” He likened it to “the Buddha, just sitting there.”
By comparison, he said, the Sagittarius black hole was “whirling.” An orbit around it can take as little as four minutes or as long as a half-hour, depending on how it is spinning. “So over a night of observing. it’s changing while you’re collecting data,” he said. “You’re trying to trying to take a picture of something with the lens cap off and you just get this blurry mess.”
Dr. Doeleman’s new goal is to expand the network to include more antennas and gain enough coverage to produce a movie of the Sagittarius black hole. The challenge for black-hole cinema will be to separate what stays the same from what changes — to delineate the underlying structure of the black hole from the matter that is moving around in it.
The results could be spectacular and informative, said Janna Levin, a gravitational theorist at Barnard College of Columbia University, who was not part of the project. “I’m not bored with pictures of black holes yet,” she said."
Tuesday, May 10, 2022
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Clearview AI settles suit and agrees to limit sales of facial recognition database.
Clearview AI settles suit and agrees to limit sales of facial recognition database.
“The facial recognition software maker is largely prohibited from selling its database of photos to private companies.
Clearview AI, the facial recognition software maker, on Monday settled a lawsuit brought by the American Civil Liberties Union and agreed to limit its face database in the United States primarily to government agencies and not allow most American companies to have access to it.
Under the settlement, which was filed with an Illinois state court, Clearview will not sell its database of what it said were more than 20 billion facial photos to most private individuals and businesses in the country. But the company can largely still sell that database to federal and state agencies.
The agreement is the latest blow to the New York-based start-up, which built its facial recognition software by scraping photos from the web and popular sites, such as Facebook, LinkedIn and Instagram. Clearview then sold its software to local police departments and government agencies, including the F.B.I. and Immigration and Customs Enforcement.
But its technology has been deemed illegal in Canada, Australia and parts of Europe for violating privacy laws. Clearview also faces a provisional $22.6 million fine in Britain, as well as a 20 million-euro fine from Italy’s data protection agency.
“Clearview can no longer treat people’s unique biometric identifiers as an unrestricted source of profits,” Nathan Freed Wessler, a deputy director with the A.C.L.U.’s Speech, Privacy and Technology Project, said in a statement about the settlement. “Other companies would be wise to take note, and other states should follow Illinois’s lead in enacting strong biometric privacy laws.”
Floyd Abrams, a First Amendment expert hired by Clearview to defend the company’s right to gather publicly available information and make it searchable, said the company was “pleased to put this litigation behind it.”
“To avoid a protracted, costly and distracting legal dispute with the A.C.L.U. and others, Clearview AI has agreed to continue to not provide its services to law enforcement agencies in Illinois for a period of time,” he said.
The A.C.L.U. filed its lawsuit in May 2020 on behalf of groups representing victims of domestic violence, undocumented immigrants and sex workers. The group accused Clearview of violating Illinois’s Biometric Information Privacy Act, a state law that prohibits private entities from using citizens’ bodily identifiers, including algorithmic maps of their faces, without consent.
“This is a huge win for the most vulnerable people in Illinois,” said Linda Xóchitl Tortolero, a plaintiff in the case and the head of Mujeres Latinas en Acción, an advocacy group for survivors of sexual assault and domestic violence. “For a lot of Latinas, many who are undocumented and have low levels of IT or social media literacy, not understanding how technology can be used against you is a huge challenge.”
One of Clearview’s sales methods was to offer free trials to potential customers, including private businesses, government employees and police officers. Under the settlement, the company will have a more formal process around trial accounts, ensuring that individual police officers have permission from their employers to use the facial recognition app.
Clearview is also prohibited from selling to any Illinois-based entity, private or public, for five years as part of the agreement. After that, it can resume doing business with local or state law enforcement agencies in the state, Mr. Wessler said.
In a key exception, Clearview will still be able to provide its database to U.S. banks and financial institutions under a carve-out in the Illinois law. Hoan Ton-That, chief executive of Clearview AI, said the company did “not have plans” to provide the database “to entities besides government agencies at this time.”
The settlement does not mean that Clearview cannot sell any product to corporations. It will still be able to sell its facial recognition algorithm, without the database of 20 billion images, to companies. Its algorithm helps match people’s faces to any database that a customer provides.
“There are a number of other consent-based uses for Clearview’s technology that the company has the ability to market more broadly,” Mr. Ton-That said.
As part of the settlement, Clearview did not admit any liability and agreed to pay $250,000 in attorneys’ fees to the plaintiffs. The settlement is subject to approval by an Illinois state judge.“
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Chaotic and crass: a brief timeline of Elon Musk’s history with Twitter | Elon Musk | The Guardian
Chaotic and crass: a brief timeline of Elon Musk’s history with Twitter
"The billionaire’s purchase of humanity’s ‘digital town square’ is a culmination of his controversial past on the platform
One of Twitter’s most controversial users became its owner on Monday, after Elon Musk brokered a $44bn deal to purchase the company.
The move was in many ways the culmination of the billionaire’s long history with the platform. Musk has been on Twitter since 2009 and tweeted as early as 2017expressing interest in buying it. He has also been a vocal critic of Twitter, calling for changes including rolling back content moderation and prioritizing a “societal imperative” of free speech.
A prolific user, Musk has 84 million followers on his account – with whom he shares memes, news about his electric vehicle company Tesla and, like the majority of Twitter users, pithy commentary on his day-to-day life.
But Musk’s tweets are not all fun and games. The executive has faced major backlash – and in some case legal action – for his activity online.
Here are some of the key moments in Musk’s Twitter history.
A $40m tweet
Musk’s activity has in some cases cost him dearly.
In August 2018, he posted that he had funding to take Tesla private at $420 per share – a joking reference to marijuana. But the Securities and Exchange Commission (SEC) concluded after investigation the tweets had no basis in fact and hurt investors, issuing two separate fines to Musk and Tesla of $20m.
The penalty marked a “warning for all those who make public pronouncements without regard for either the accuracy or impact of their words”. (Musk maintainsthat the joke was “worth it”).
Part of that 2018 settlement included a clause that Musk would have legal counsel approve tweets about Tesla in advance to ensure they do not contain market-moving news. Musk, unsurprisingly, has not abided by those conditions, flippantly wiping $14bn off Tesla’s value in 2020 with a tweet stating that “Tesla stock price is too high”.
Musk again ran into SEC troubles when in 2021 he tweeted a poll about whether to sell his stock and proceeded to do just that. The Tesla CEO and his brother are now under investigation for insider trading relating to whether Musk told his brother in advance that he would tweet the poll.
The frequent investigations and legal actions have rankled Musk, whose lawyer said in a legal filing in March that the SEC investigations constitute “outsized efforts calculated to chill [Musk’s] exercise of First Amendment rights”.
Cave diver drama
Musk’s Twitter feuds brought him into a Los Angeles courtroom in 2019, where he faced trial for defamation relating to tweets and other statements he made about the British cave diver Vernon Unsworth.
Musk had grown angry after the caver ridiculed him over his plans to rescue a team of young footballers from a cave system in Thailand, baselessly calling Unsworth a “pedo guy” in a tweet to Musk’s then 22 million followers.
The Tesla executive later apologized and deleted the tweets after intense criticism from the public and his investors, but re-upped the baseless claims in another series of tweets about a month later and doubled down on them in an on-the-record email to a BuzzFeed reporter.
Musk testified in court that he had not meant to be literal in his tweet and that he was upset at the time at what he called “an unprovoked attack on what was a good-natured attempt to help the kids”.
“It was wrong and insulting, and so I insulted him back,” Musk said. He was ultimately exonerated.
Unhappy shareholders
Backlash from Musk’s tweets has also come from shareholders. He is being sued in an ongoing lawsuit filed by investors who say his 2018 “420” tweet was inaccurate and hurt the company.
Another suit filed by a shareholder in 2021 claims that Musk’s tweets had caused “billions of dollars in losses”, and specifically references a feud between Musk and Senator Elizabeth Warren, which allegedly drove down the stock price another 9.6% in December as well as the poll over whether to sell stock.
“Musk remains undeterred and continues to post on Twitter and social media on matters that are material to Tesla and its stockholders, and which ultimately have an impact on Tesla’s stock prices,” the lawsuit says.
Meeting Grimes
The platform has also played a large role in Musk’s personal life: he reportedly met his former partner Claire Boucher (known as Grimes) via Twitter.
When the couple went public with their relationship in 2018, Page Six reportedthey met when Musk went to tweet an elaborate pun about artificial intelligence and found Boucher had already made the joke years earlier.
The pair, who have since communicated publicly on Twitter often, have two children together. An SEC filing said Musk even made his infamous 420 tweet in 2018 because he “thought his girlfriend ‘would find it funny’.”
Covid-19 controversy and other antics
Even when they are not moving markets, Musk’s tweets are often chaotic and crass (he said he sends them mostly from the toilet). He has received criticism for a number of tweets downplaying the severity of Covid-19 and speaking outagainst lockdowns. He tweeted (then deleted) a meme comparing the Canada prime minister Justin Trudeau to Hitler over Covid-19 vaccine mandates.
Elsewhere over the years, Musk has promised Tesla vehicles would be purchasable in Bitcoin and then walked back that announcement, joked aboutquitting his job and becoming an influencer, and mused about nuking the planet Mars.
Musk’s freewheeling personal style on Twitter has caused many to express concern about his takeover of the company, and whether his “free speech” mentality will translate to harmful policies.
“Musk hasn’t just purchased another expensive play toy, but a global online community that includes about 330 million regular users,” said Jessica J González, co-chief executive of media reform advocacy non-profit Free Press. “With control of such a massive platform comes great responsibility – and Musk hasn’t shown he has the capacity to be accountable to this diverse online community.”