What do you call a bunch of black holes: a crush? A scream?

What do you call a black hole? Anything you want, the old joke goes, as long as you don’t call him late for dinner. Black holes, after all, are nothing but hungry.

But what is a collection of black holes called? The question has taken on urgency among astronomers inspired by recent reports of dozens of black holes buzzing around the center of a nearby star cluster.

In recent years, instruments such as the LIGO and Virgo gravitational wave detectors have recorded space-time vibrations from collisions of black holes, making it clear beyond doubt that these monstrous concentrations of nothingness not only exist but are omnipresent. Astronomers expect to spot large numbers of these Einsteinian creatures when the next generation of gravitational wave antennas are deployed. What will they call them?

There are flocks of geese, flocks of whales and killings of ravens. What term would do justice to the special nature of black holes? A mass? A colander? A scream?

Jocelyn Kelly Holley-Bockelmann, an astrophysicist at Vanderbilt University, and colleagues are developing an international project called the Laser Interferometer Space Antenna, or LISA, which will be able to detect collisions between black holes of all sizes throughout the universe. She was trying to organize a Zoom group meeting recently “when one of the members said her daughter was wondering what a black hole collective is called – and then the meeting fell apart, with everyone trying to get each other up. “he said. in an email. “Whenever I saw a hint, I had to stop and giggle like crazy, which made us all cheer on more.”

The question was crowdsourcing on Twitter recently as part of what NASA has begun to call Black Hole Week (April 12-16). Among the many candidates so far: A crush. A mosh pit. A silence. A speck. A beehive. An enigma. Or one of my favorites for its connection with my youth: an Albert Hall of black holes.

The number of known black holes will only grow. LISA will be able to detect so-called primordial black holes, if any, left over from the earliest moments of the Big Bang, as well as more recent ones, presenting researchers “basically a smorgasbord black hole,” Dr Holly-Bockelmann said. The antenna won’t fly until 2034, he added, “so there’s time to figure out the term if and when we need it!” The International Astronomical Union, which regulates the cosmic nomenclature, has no rules on “collectives,” he added, so it’s up to the people to decide.

Dr Holly-Bockelmann added that among her personal preferences was “a ‘void’ of black holes”. My own candidate is a “disaster” of black holes, since the word disaster is rooted in the Latin “astro” – star – and, later, in the Italian word for “unfortunate”.

The previous black hole week was in the fall of 2019, when NASA reproduced some of the scariest cosmic news, involving black holes exploding, eating stars, or preparing to consume their neighborhoods. Now, against the backdrop of a global pandemic, black holes offer a respite and a reminder of how small and fleeting our problems are in the larger scheme. Black holes have become the videos of astronomy cats.

So last week, NASA offered another smorgasbord of black hole news and public service announcements, like this animated video from NASA’s Goddard Space Flight Center.

You can’t visit a black hole, of course, but astronomers came up with the best thing two years ago: the first ever image of one. The supermassive black hole – 6.5 billion suns of vanishing mass – is located at the center of the galaxy Messier 87.

The image was taken by a worldwide network of radio telescopes known as the Event Horizon Telescope in April 2017. Last month, the Event Horizon team refined that image to show the surrounding vortex of magnetic fields that transmit gas and energy. through space almost speed of light.

But there is more. As the first image of 2017 was being taken, 19 other observers in space and on the ground were collectively studying this blast of energy from M87. Their data has now been released alongside a video of the jet seen in different types of light and at different scales, from the more intimate dimensions of the black hole to intergalactic space.

The findings, the astronomers said, would help clarify how black holes operate with their violent magic, further test the predictions of Einstein’s general theory of relativity, and perhaps shed light on the origin of cosmic rays.

For its part, the Event Horizon team has just completed a new series of black hole observations – in M87, at the center of our galaxy and elsewhere – said Shep Doeleman, of the Harvard-Smithsonian Center for Astrophysics and founding director of il telescope collective.

“Every day we meet at 2 pm EDT to review all the time and availability at the sites, then make the call,” Dr. Doeleman said in an email. “Sometimes it’s child’s play: good weather, everyone is ready. Or, equally clear, the weather at key sites is horrible or there is a major technical problem to be solved. Sometimes it’s pure agony. “

If you don’t have a rocket or a telescope, there is a lot of news to read about black holes. “Hawking Hawking: The Selling of a Scientific Celebrity,” by Charles Seife, is an unpainted look at cosmologist and black hole expert Stephen Hawking, who died in 2018. The book, full of news about Dr. Hawking’s findings and his life (and written in reverse chronological order), seeks to separate man and his science from Einstein’s aura of sagacity that has allowed his public persona to envelope.

And “Black Hole Survival Guide,” by Janna Levin, an astrophysicist at Barnard College at Columbia University, and illustrated by artist Lia Halloran, is a pocket poem about these cosmic curiosities.

“Black holes are nothing,” reads the opening line. Eventually, Dr. Levin contemplates the possibility that Earth and everything else on it will fall into the black hole at the center of the Milky Way.

“This is where our data can end up, our bits of quantum information,” he writes. “Everything will sweep away the central vortex, flashing spectacularly, the last desperate bursts of concentrated light in the cosmos, until it all fades into a dark, silent storm in space-time.”

And we could also call the entire universe a graveyard of black holes. A buffet of screams – just another week of black holes.