Never play games with a bot (机器人)—it will find a way to cheat if it can. A team from OpenAI, an artificial intelligence lab in San Francisco co-founded by Elon Musk, has developed artificially intelligent bots that taught themselves to cooperate by playing hide-and-seek. The bots also learned how to use basic tools and that disobeying the laws of physics can help to win.

In April, 2019, a team of bots known as the OpenAI Five beat the human world champions at the team-based video game Dota 2. The hide-and-seek bots use similar principles to learn but the simpler game allows for more inventive play.

Bowen Baker at OpenAI and his colleagues wanted to see if the team-based dynamics of the OpenAI Five could be used to create skills that could one day be useful to humans. The researchers set their bots loose in a simulated (模拟的) environment filled with fixed walls and movable boxes and left them to play team games of hide-and-seek millions of times. The bots each had their own view of the world and couldn’t communicate with each other directly. At first, the hiders simply ran away. However, they soon worked out that they could find objects in the environment to hide themselves from view. For example, they learned that boxes could be used to block doorways and build simple hiding places. The seekers learned that they could move a ramp (斜坡) around and use it to climb over walls. The bots then discovered that being a team player was the quickest way to win.

The hiders also learned to sabotage the other team, such as hiding the ramp before hiding themselves so that the other team can’t make use of the ramp. “Once one team learns a new strategy, it creates this pressure for the other team to adapt,” says Baker.

Such tricks show that AIs are able to find solutions that humans miss, says Baker. “Maybe they’ll even be able to solve problems that humans don’t yet know how to,” However, there’s still a long way to go from online hide-and-seek to real problem-solving.

Astronauts drink their own pee (尿)—after it's been cleaned. 【小题1】 Many experts, though, argue that recycling pee and other waste is an excellent and safe solution when there isn't enough fresh water to go around.

【小题2】 All of the water that astronauts use to drink, brush their teeth, or make coffee comes out of one limited container that has to be resupplied—from Earth. To help conserve water, the waste from sinks, toilets, and even the pee from lab animals on board flows into a recycling system. First, the water goes through a series of filters(过滤器) to get rid of large particles(微粒) and impurities. Then, chemical reactions remove poisonous chemicals and kill any bacteria or viruses. 【小题3】

Chris Hadfield, who lived on the space station for five months, says, "Before you feel uncomfortable with the thought of drinking your leftover wash water and your leftover pee, keep in mind that the water that we end up with is purer than most of the water that you drink on a daily basis at home."

Astronauts, however, tend to be more adventurous than the average person. On Earth, cities in very dry parts of the world have attempted to introduce wastewater purification systems. 【小题4】 Citizens recoiled(退缩) in disgust. Despite scientific evidence that the water is clean, many people just can't get over the fact that it once flowed through a toilet. In the 1990s, activists in San Diego and Los Angeles campaigned against "toilet to tap" water. 【小题5】 In a survey of 2,000 Americans, 26 percent agreed with the statement: "It is impossible for recycled water to be treated to a high enough quality that I would want to use it."