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Is it hopeless to try to compute the shortest route to visit a large number of cities? Not just a good route but the guaranteed shortest. The task is the long-standing challenge known as the traveling salesman problem, or TSP for short. Finding a method that can quickly solve every example of the TSP would be a stunning breakthrough in mathematics. Using complexity theory, such a method would allow us to solve efficiently any computational problem for which answers can be easily verified....

Opioids. Fracking. Zika. GMOs. Scientists should be speaking up about all sorts of science-based issues that affect our lives. Especially now, when Trump administration officials tell us that climate change is debatable and that killing African elephants can benefit the herd, scientists should be constantly exposing misinformation, bogus alternative facts and fake science. Unfortunately, the greatest obstacle to informing the public may be the very universities that many scientists work for....

We are in the midst of a once-in-a-generation opportunity to remake our approach to science. This moment, in all its difficult uncertainty—COVID-19, economic turmoil and the crescendo of a long overdue national discussion about racial justice—demonstrates why universities, funders and other research stakeholders should move decisively to embrace open science. By adopting what are called “open science” practices, we can align the incentive structures of research production and consumption with our values, and catalyze the scientific progress our society so desperately needs....

In 1964—exactly 50 years ago—sci-fi author Isaac Asimov wrote up his predictions about what life today would be like. He had a lot of hits and a lot of misses, as I wrote in my Scientific American column this month. But Asimov wasn’t the only person to look into the technological crystal ball. Fifty and 60 years ago gee-whiz films depicting life today were a staple—a sure way to wow audiences....

Glaciers in Greenland and Antarctica are losing ice at alarming rates, and warmer air isn’t the only cause. Scientists increasingly agree that warm ocean water is seeping beneath the ice and melting it from the bottom up. It’s a growing problem in Greenland, scientists say, and it may already be the dominant driver of melting glaciers in Antarctica. But while scientists know that warm water is interacting with the ice front in both places, exactly what’s driving it there—and how climate change may be involved—is still an open question....

We all wish we could get by on less sleep, but one father and son actually can—without suffering any health consequences and while actually performing on memory tests as well as, or better than, most people. To understand this rare ability, researchers at the University of California, San Francisco, first identified a genetic mutation—in both individuals—that they thought might deserve the credit. Then the scientists intentionally made the same small genetic spelling mistake in mice....

If possible, think back to a time you or a loved one had to be in a hospital for a significant amount of time. What do you remember from the experience? Many people report an eerie feeling about their stays in hospitals. Even if everyone treating you was kind, attentive, hard working, efficient and competent, you may still have had a sense that—compared to other situations in which people were intensely looking after you—something was different about being in the hospital....

Are you an early-rising lark or a night owl? These terms have gained scientific credibility, with researchers determining such differences have a basis in genetics. The sci-fi-sounding jargon for this inclination is your “chronotype,” and it can create significant discrepancies between your internal biological time and the external time shown by the clock on the wall. Now three teams of scientists are converging on a way to read a person’s internal time from blood samples....

On May 1 South Africa began to slowly open its stores and economy after a five-week lockdown to limit the spread of COVID-19. The key to this loosening of restrictions, the government and scientists say, is a plan to quickly spot new disease flare-ups and isolate them before they spread further. To do so, officials are relying on technology that integrates different types of health and location data about individuals across the country—a tool based on software that was used to identify rhinoceros poaching hotspots in South Africa’s national parks....

There had to be a sinking feeling in the chest of every researcher who works in a high-containment research laboratory last Friday when the U.S. Centers for Disease Control and Prevention (CDC) released its report on three worrisome incidents that raised safety questions at two well-respected government facilities. But it is likely the sensation was most acute for the influenza scientists who work in a controversial field known as gain-of-function research....

Less than a quarter of a century after emerging from a military dictatorship, Brazilians have built a stable and vibrant democracy in which more than 80 million voters freely decide the future of their beloved country in each and every election. Lately, by becoming a world leader in food production, spearheading the search for biofuels as a new source of renewable energy and seeking ways to grow its economy while still protecting its unique natural ecosystems, Brazil has started to address a broad range of difficult and unavoidable issues that currently challenge most developing nations worldwide....

The worst cancer cells don’t sit still. Instead they metastasize—migrate from their original sites and establish new tumors in other parts of the body. Once a cancer spreads, it is harder to eliminate. A study by developmental biologists offers a fresh clue to how cancer cells acquire the ability to invade other tissues—a prerequisite for metastasis. It reveals that invasion requires cells to stop dividing. Therefore, the two processes— invasion and proliferation—are mutually exclusive....

DATONG, China – A decade ago, this ancient capital city in northern China was shrouded in coal dust. Now, in an ambitious bid to rebrand itself as a solar city, Datong has played host this week to Asia’s first-ever Solar Decathlon, an international intercollegiate competition organized by the U.S. Department of Energy to promote innovative solar-powered residential designs. An Asian team, the South China University of Technology, came in second among 20 teams from around the world in designing a single-family home that operated exclusively on solar energy during the two-week-long contest....

You could be forgiven for missing that the qualifying matches for a big youth soccer event—the Africa Cup of Nations—are underway right now, what with the Olympics taking center stage all week. But then you might miss the latest “doping” scandal playing out in soccer headlines: Almost half of Nigeria’s U-17 (under age 17) team has been sidelined based on lab scans. Yet the dismissal is not over a traditional malfeasance such as performance-enhancing chemicals or hormonal supplements....

Sometime in the 14th century, the first Mexica found their way into the valley of Teotihuacán. The Mexica (often incorrectly called Aztecs in modern times) were new to the region. An aggressive, ambitious people from the north, they were fast becoming the dominant force in highland Mexico, conquering territory and setting up the powerful city of Tenochtitlán, which would soon rule a massive empire from what is now called Mexico City....

One body rests on its left side, head and neck pulled back toward the pelvis—a classic death pose. The arms and legs are still in their anatomically correct positions, but closer inspection reveals that bones of the hands and feet are dislocated, although most parts are present and accounted for. The skull, too, is somewhat disjointed, and here again the component pieces lie near one another. Curiously, the tip of the tail is missing altogether....

After decades of hunting, astronomers have tracked down the origin of a nova first recorded by Korean royal astrologers nearly 600 years ago. This finding is the oldest-known example of such a stellar explosion with an accurately pinpointed location, the new study’s researchers said, and it could help shed light on the nature of novas, and on the way that about three-quarters of all stars evolve. On March 11, 1437, Korean astronomers detected what seemed like a bright new star in the night sky....

From Nature magazine A navy-blue world orbiting a faraway star is the first exoplanet to have its colour directly measured. Discovered in 2005, HD 189733 b is one of the best-studied planets outside the Solar System, orbiting a star about 19 parsecs away in the Vulpecula, or Fox, constellation. Previous efforts to observe the planet focused on the infrared light it emits — invisible to the human eye. Last December, astrophysicist Tom Evans at the University of Oxford, UK, and his colleagues used the Hubble Space Telescope to observe the planet and its host star....

Last week, I towed first aid to a local protest championing the Movement for Black Lives. I felt elated to witness the coalescence of community, but as a street medic I was too anxious to enjoy the walk. That morning, our surgical service had sent out a department e-mail outlining hospital protocol for mass casualty provisions in preparation for the event. The civilian protestors were not the ones we were afraid of....

Former Secretary of State Hillary Clinton, if elected president, likely wouldn’t prioritize a sweeping rule on climate, her campaign chairman, John Podesta, said Friday. The front-runner for the Democratic presidential nomination would want to work with Congress on climate action, Podesta said. But she’d probably focus on smaller legislative actions and employ executive powers, given Republican opposition to many global warming measures. “I’d like to see a price on carbon, but I’m more optimistic about persuading Congress to support more investment in clean energy, more investment in energy efficiency, more investment in research and development,” Podesta said....