Scientists are poor forecasters of the future. But two trends can be confidently predicted. First, the world will get more crowded. There will be more than 9 billion people by 2050. Second, the world will get warmer and some governments won't prioritize the long-term measures needed to deal with climate change, even though science offers us a road-map to a low-carbon future.

That's why we should be promoters of new technology—without it the world can't provide the food and sustainable energy needed for an expanding population. But we should also be cautious, as new technologies, such as AI, may be hard to control. AI will undoubtedly become more aggressive in the future. Records of our movements, health and financial transactions will be stored in the cloud. The data may be used for justifiable reasons, such as protein folding and drug development, or to warn us of initial health risks, but its availability to Internet companies is already shifting the balance of power from governments to global-scale corporations.

Actually, it's beyond Earth that AI has the most enormous potential. Humans may have established bases beyond Earth by the year 2100. But don't ever expect mass emigration(移民)from Earth. It's a false belief that space offers an escape from our problems. Dealing with climate change on Earth is a piece of cake compared to terraforming(地球化)Mars.

Nevertheless, we should cheer on these brave human space adventurers. They'll be ill-adapted to a Martian habitat, so they'll have a super motive to redesign themselves. It's they, not those of us adapted to life on Earth. who will pioneer the post-human era (时代).

If post-humans make the shift from flesh and blood to fully artificial intelligence, they won't need an atmosphere of even gravity, so it's in deep space —not even on Mars that non biological "brains" may develop powers that we can't imagine. They may end up being mentally different from us. AI could jump-start a huge emigration and thus even more complex intelligence spreads through the universe.

But let's refocus from the science fiction of the far future, closer to the here and now. This century is special. It's the first, in Earth's 4.5-billion-year history where one species-ours—holds the planet's future in its hands. Our intelligence could initiate billions of years of post-human evolution(演化), even more amazing than that which led to us. On the other hand, humans could cause biological, environmental or cyber catastrophes that foreclose all this potential. If science is to save us, we need to think globally, sensibly and long-term—empowered by science, but guided by values that science alone can't provide

The Neurosurgical Simulation （神经外科模拟） and Artificial Intelligence Learning Centre hired 70 medical students to perform virtual brain tumor removals.

Researchers randomly assigned students to receive instruction and feedback by either an AI tutor or a remote expert instructor, with a third control group receiving no instruction. An AI-powered tutor called the Virtual Operative Assistant （VOA） used a machine learning algorithm to teach safe and efficient surgical technique and provided personalized feedback, while a deep learning system and a team of experts assessed student performance. In the other group, remote instructors watched a live feed of the surgical simulations and provided feedback based on the student's performance.

The researchers found that students who received VOA instruction and feedback learned surgical skills 2. 6 times faster and achieved 36% better performance compared to those who received instruction and feedback from remote instructors. Surgical skill plays an important role in patient outcomes both during and after brain surgery. VOA may be an effective way to increase neurosurgeon performance, improving patient safety while reducing the burden on human instructors. "Artificially intelligent tutors like the VOA may become a valuable tool in the training of the next generation of neurosurgeons, " says Rolando Del Maestro, senior author of the study in JAMA Network Open. "The VOA significantly improved expertise while fostering an excellent learning environment. Ongoing studies are assessing how in-person instructors and AI-powered intelligent tutors can most effectively be used together to improve the mastery of neurosurgical skills."

"Intelligent tutoring systems can use a variety of simulation platforms to provide almost unlimited chances for repetitive practice without the constraints imposed by the availability of supervision," says Ali Fazlollahi, the study's first author. "With continued research, increased development, and dissemination （宣传） of intelligent tutoring systems, we can be better prepared for ever-evolving future challenges."

Jim Curry lights a stove in the parking lot of Christ Episcopal Church in Guilford. It'll get up to 2,000 degrees, hot enough to soften the metal of shotgun parts so they can be reshaped.

A crowd is watching, and Curry picks out a 9-year-old named Oliver to help him. "This is really magic," Curry says. "Right before your very eyes, you're gonna see Oliver transform this gun, this instrument of potential harm, into something that could never be a gun ever again. It's gonna be a trowel (泥铲), which could be used to plant flowers in a garden."

"It is exciting," Oliver says. "I love the fact that you can take metal that's random and shape it into something useful."

Curry, a retired priest, is a co-founder of Swords to Plowshares (犁) Northeast, the organization putting on this event, which helps police departments manage their gun buyback programs and repurpose the weapons into gardening tools.

The finished tools are donated to community gardens and agricultural high schools and the harvested vegetables donated to soup kitchens and homeless shelters, according to the group's website.

Retired priest Mary Ann first volunteered with Swords to Plowshares when a family member fell victim to gun violence. She helps collect guns through police buybacks. "When there's such despair now in our country, people need to know that we can change. There is hope," she says.

Curry wears a constant reminder of that hope around his neck. It's two large pieces of metal molded into the shape of a cross. "It's made out of pieces of an AK-47 used for killing", he says. "But God's love breaks it apart, reshapes it, then transforms it into the sign of greatest hope — the cross. And that's why I wear it."