Rocky Balboa would be proud. Halfway across the Milky Way, a gas cloud has punched a hole in the galaxy, leaving a blast wave and a gaping void 3000 light years across.

Compared with our galaxy, this cloud, named CHVC040, is a lightweight: only 16,000 times the mass of the sun. It is moving at high velocity and should have disintegrated on impact with the galactic disc, according to simulations, so it’s a mystery how it created this hole.

The galaxy is dotted with these spherical abysses, called supershells. Most are thought to be caused by a series of supernova explosions, when the hottest young stars in a cluster blow themselves to bits. The expanding blast waves burst through the galaxy with an energy equivalent to dozens of such exploding stars

But many supershells have no trace of star clusters at their centre, so there might be other causes.

One suggestion was that the compact clouds of gas that swarm around the Milky Way might be jabbing into the disc from above and below, causing explosive impacts. Much larger clouds have been spotted ploughing through the galaxy, but whether the smaller ones could make a mark remained an open question. Supershells dissipate quickly, and evidence of such a collision has been hard to come by.

Blast waves

Until this one. A pair of South Korean astronomers with no apparent cause back in 2007. But when Seoul National University graduate student Geumsook Park took a close look at new data from the highly sensitive in Puerto Rico, she saw a compact high-velocity cloud smack dab in the middle of the shell.

When she showed the data to , her adviser and one of the supershell’s discoverers, he got excited. “I knew that this was important,” he says. “I think this is the first convincing example.” Park and Koo think the odds that the cloud and the shell could appear together by chance are exceedingly low.

Understanding just how these shells form should tell us more about the lifecycle of stars in the universe, as the blast waves from supershells are thought to sweep up debris into clumps that turns atomic gas into molecular clouds, which then become the next generation of stellar nurseries.

Interpreting three-dimensional structure from radio data can be tricky, says astronomer of Macquarie University in Sydney, but she finds the results convincing. The supershell is in relatively empty space, well below the densest part of the Milky Way disc, so exploding stars are unlikely to have made it. “I pretty much bought it,” she said. “It’s really nice to see an article where they have some reasonable evidence that a cloud is smashing through the disc and forming a shell.”

Journal reference: Astrophysical Journal Letters,

Maybe AlphaGo is fallible after all. Korean Go master Lee Sedol claimed victory over Google DeepMind’s Go-bot on Sunday, his first in the five-game series.

It came too late to affect the outcome of the series – AlphaGo clinched it on Saturday with its third straight win. But Lee’s victory reversed the event’s sombre tone, inspiring the Go community, and the entire region.

After his win, Lee strolled into a press conference to unrestrained cheers from reporters, chants of “LEE-SE-DOL”. He acknowledged them almost shyly, with a slight bow, his eyes on the floor. But the grin on his face was a picture of relief.

“If I had lost one game, it would have hurt tremendously,” he said. “But because I lost three matches and got this single win, I wouldn’t exchange it for anything in the world.”

The day before, he had lost to AlphaGo’s most complete performance yet, falling behind early and never recovering.

“It was so hard to watch,” said Andrew Jackson of the . “He just got steamrolled.”

Astonishing play

In Sunday’s game, Lee started conservatively, ceding the centre of the board. But on move 78, he turned the game around with an astonishing wedge play in the middle. Gu Li, one of Lee’s rivals, commenting on the game in China, called it the “hand of god”, the kind of language that was being applied to AlphaGo in previous games.

AlphaGo responded to the unexpected move with a weak counter, which set off a brilliant sequence from Lee to capitalise. According to Demis Hassabis, one of DeepMind’s founders, AlphaGo didn’t realise its mistake until eight moves later. “Lee Sedol beat AlphaGo at its own game,” said Jackson.

Watch the best human player take on the mighty AlphaGo AI at Go

Lee sat up straighter as he closed in on victory. The press room began to buzz as AlphaGo played increasingly bizarre moves, the death throes of an algorithm. Across the table from Lee, Aja Huang, the AlphaGo programmer who acts as its human avatar and places its stones on the board, appeared resigned. And then, a message appeared on his monitor: “The result ‘whiteresign’ was added to the game information. AlphaGo resigns.”

Lonely fight

After the third match, with camera shutters clicking, Lee had apologised “for not being able to satisfy a lot of people’s expectations”. More than one reporter later admitted to holding back tears. Lee stressed it was not humanity’s defeat, but his alone. He said that the pressure had got to him, and that he felt “kind of powerless”.

One of Lee’s fellow pros, Lee Hyun-wook, paid tribute to his heart and spirit. “He is fighting such a lonely fight, and a hard fight against this invisible opponent.”

The next day was an emotional 180. Yet, in his moment of victory, if Lee cracked a smile, I didn’t see it. His focus was back on the board, replaying the game.

In Go, it’s customary to go over the match with your opponent to share your thought process. But across from Lee, there was only Aja Huang, looking around, unable to explain any of AlphaGo’s blunders. As he left his chair, Lee gave him barely a nod. In victory, just as in defeat, Lee Sedol was utterly alone.

Read more: Does a machine beating a Go master mean human-like AI is close?

Read more: ‘I’m in shock!’ How an AI beat the world’s best human at Go

Read more: Google AI program crushes Korean Go legend again in round two

Hard, cold intelligence

Watch the best human player take on the mighty AlphaGo AI at Go

Humanity’s machines just outstripped us, again. A few hours ago in Seoul, South Korea, an artificial intelligence built by Google defeated top player Lee Sedol in one of our most complex games, Go.

“This is history, you saw it folks,” said Chris Garlock of the American Go E-Journal, one of the match’s commentators. The match was the first of a five-game series in Seoul.

As the game reached its conclusion, the reality of Lee’s defeat set in slowly across the venue, prompting quiet gasps of shock. This was stark contrast to Tuesday, when some Korean journalists had openly cheered Lee at a press conference. It was hard not to feel sympathy with Lee as I watched this opening defeat. He carries the hopes of a nation – not to mention a species – on his shoulders.

The news, that artificial intelligence has defeated humanity’s best Go player, has sent shock waves through the international Go community. “I felt emotional and dizzy, and stepped outside for a minute,” said Ben Lockhart, one of the top US amateur players, watching on in the press room.

AlphaGo made headlines in January when DeepMind – an artificial intelligence company that Google bought in 2014 – announced that its AI had defeated reigning European champion Fan Hui 5–0. Most observers had thought such an AI was a decade away. That prompted DeepMind to challenge Lee, considered the game’s dominant force of the last decade.

Putting on a show

The match against Fan was played in secret. Not this one. Google’s AlphaGo is facing off against Lee Sedol in the swanky Four Seasons hotel in the heart of downtown Seoul. The match has captured public imagination in Korea, with dozens of cameras and hundreds of reporters descending on the match site. The press filled two separate conference rooms – one with English commentary and one with Korean.

The match itself took place in a room that organisers wouldn’t disclose. There, isolated from outside noise, Lee sat across the board from Aja Huang, one of AlphaGo’s lead programmers, who referred to a monitor plugged into AlphaGo. A sign gave their names and flags – a Union Jack for Google DeepMind’s London headquarters.

Watch the best human player take on the mighty AlphaGo AI at Go

Go is riding a recent wave of pop culture relevance here in Korea, thanks to a couple of recent TV dramas featuring Go players. The game was televised live across Korea, China and Japan, where the game is most popular, and . On Naver, the top Korean search engine, combinations of “Lee Sedol” or “AlphaGo” were the top three search terms on the day of the match.

Human nature

Lee Sedol is a national hero in his native South Korea, known for his unconventional and creative play, as well as his brashness. He flashed his swagger at , predicting he would win in a “landslide”. “Of course, there would have been many updates in the last four or five months, but that isn’t enough time to challenge me,” he said.

But after watching DeepMind explain the algorithm at a press conference on Tuesday, Lee admitted to being “quite nervous” and backed off from his 5–0 prediction.

Lee had been in fine form, with a runner-up finish in the world championship and victory in the Korean national championship in January, where it is known as baduk. Most professional players thought that based on AlphaGo’s play in October, Lee would win handily. But no one knew how much progress it had made, or how it would respond to tougher competition.

Play-by-play

Lee showed his opening gambit in the game’s seventh move, with an unusual play in the middle right of the board, allowing him to stake out territory along the right side of the board. But AlphaGo continued to push, playing unconventionally for a human. “It’s unheard of! It’s crazy,” said Jackson.

AlphaGo fell further behind in the midgame with a bizarre stretch of moves that had observers shaking their heads. But as it fought back over the rest of the match, Lee grew agitated, dabbing at his chin with his fist and tapping his finger on the side of the board. “I’ve never seen him so nervous before,” said Lockhart.

The match ended in what Garlock called a “slugfest”, with AlphaGo’s performance impressing. “It’s all that I hoped for or expected,” said Michael Redmond, one of other commentators and the only Western Go pro to have reached 9-dan, the game’s highest level.

As the endgame played out, Lee appeared downbeat, his hands shaking at every move. He flashed a wan smile as he resigned.

The question is whether Lee can recover. In AlphaGo’s previous match, experts say Hui Fan’s moves grew erratic after dropping the first game.

“It’s so shocking. I expected AlphaGo to win one game, but I didn’t expect it to be the first one,” said Myung-wan Kim, a Korean 9-dan professional living in Los Angeles and commenting with Jackson.

“I am in shock, I admit that,” said Lee. But he said he had no regrets about accepting the challenge and planned to come back strong in the rest of the matches. “I didn’t think AlphaGo would play the game in such a perfect manner.”

For more on machine learning, watch our Explanimator video:

[youtube]https://www.youtube.com/watch?v=bctMvKrB_y0[/youtube]

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Looks like something left the lights on. The supermassive black holes at the cores of some galaxies give off a tremendous amount of light. It comes from superheated discs of gas that slowly spiral into the maws of the black holes, but where all that gas came from has been debated for decades. Now, observations reveal tell-tale signs of debris that suggest ancient galactic crashes flipped the light switch in the brightest of these “active galaxies”.

One of the main hypotheses is that the gas could be funnelled towards black holes when colliding galaxies send vast amounts of it toward their shared centre as they merge. But an alternate theory has gained traction recently, especially to explain fainter galaxies. This theory holds that the structure of galaxies becomes unstable over time and causes a self-implosion.

To test which process is more frequent, Jueun Hong and of Seoul National University in South Korea imaged 39 of these bright active galaxies, with telescopes in , and . They spent up to four hours on each galaxy to capture fine, faint details. They inspected the images for signs of a past or ongoing merger – wispy trails of stars flung violently into space during an intergalactic pile-up.

Gassy galaxies

The team found that 17 of the galaxies had such features, which was between four and eight times more than they saw in a sample of images of non-active galaxies.

Im says the results show that although both mechanisms could trigger active galaxies, mergers are the main cause for the brightest ones. “You have to have a great amount of gas supply to fuel them,” he says.

The study is “a new piece of the puzzle”, says of the National Institute of Astrophysics in Bologna, Italy. In 2011, Cappelluti and his colleagues published a study of fainter, more distant active galaxies, and found no signs of collisions. “In this paper they study much brighter sources than ours and in this case, the merger scenario works,” he says.

Journal reference: Astrophysical Journal, DOI:

Dreams and careers rest on the decision. Do you go all out in the semi-final or rest your stars so they are fresh for the final?

of Pukyong National University in Busan, South Korea, and his colleagues have applied game theory to this “semi-finalists’ dilemma”, and the results could apply in the boardroom as much as in basketball or football.

They constructed a simple mathematical model in which winning depends on stamina, which is a finite quantity that each team must choose how to distribute over its final two matches of a tournament.

In a winner-takes-all format, the best strategy is to copy what everyone else does, Baek’s team says. If your opponents rest their stars, you ought to as well. Otherwise, you risk being more tired than the opponent in the final. This sort of scenario in which no player has an incentive to go off-strategy is what game theorists call a Nash equilibrium.

Chasing bronze

But it’s different when there’s the chance of redemption in a third-place play off. You need to introduce an element of chance to catch your opponents off guard, says Baek’s team. Either go all out in the semis, or save everything for the next match. A team may be crushed in the semi-final, but saving energy increases the odds of taking home a prize: the bronze.

The work could help explain why animals sometimes seem to cooperate in nature, even when competing for a mate, says co-author of Sejong University in Seoul, South Korea. A seemingly cooperative pair of males may not be altruistic – they may have simply converged on saving their stamina for future rounds with other opponents.

The results could also guide companies in setting incentive schemes. “The pay-off system is effectively sending a signal to people on how to behave,” says Baek. For instance, a company wanting to cultivate specialists on its management team may wish to avoid paying the CEO far more than others, because that might push people to develop the same skill set to compete for the top job.

Group theory

“You could see that career structure as a bunch of subsequent stages where some proceed to the next stage and other people don’t,” says , an evolutionary game theorist at the University of Amsterdam, the Netherlands. He says the work could also be extended into exploring the game theory of an entire World Cup tournament, group stage and all: “This shows the principle.”

He says the Dutch side has reached the World Cup semis five times without solving the dilemma.

Jeong says his nation’s Olympic squad is one example of how a different pay-off structure might alter a team’s strategy. South Korean male athletes are exempted from their two years of mandatory military service if they bring back an Olympic medal, giving them an incentive to ensure they get a bronze.

It might be coincidence, but in the football at the 2012 London Olympics, South Korea suffered a 3–0 thrashing from Brazil in the semi-final, but went on to overcome arch-rivals Japan 2–0 and snatch bronze.

Journal reference: Physical Review E; journals.aps.org/pre/accepted/7807dR6fFd419718908d1c99d99366454f9e6b9a5