(Left to right): MAXIME ALIAGA; Lawrence Livermore National Laboratory; LIQUID ROBOTICS, A BOEING COMPANY

Top stories: Dancing Ph.D. students and unearthing the Great Pyramid’s secrets—with cosmic rays

Cosmic rays reveal unknown void in the Great Pyramid of Giza

Some 4500 years ago, the ancient Egyptians built the Great Pyramid of Giza as a tomb for the pharaoh Khufu, one that would ferry him to the afterlife. Now, using subatomic particles raining down from the heavens, a team of physicists has found a previously unknown cavity within Khufu’s great monument. The mysterious void, say scientists, “can’t be an accident.”

3D printing doubles strength of stainless steel

3D printing has taken the world by storm, but it currently works best with plastic and porous steel—materials too weak for hard-core applications. Now, researchers have come up with a way to 3D print tough and flexible stainless steel, an advance that could lead to faster and cheaper ways to make everything from rocket engines to parts for nuclear reactors and oil rigs.

Underwater network hunts for mysterious slow quakes

Researchers have long feared that mounting tectonic stress off the coast of the Mexican state of Guerrero could unleash an earthquake of magnitude 8 or more, toppling buildings as far away as Mexico City, which is still reeling from a magnitude-7.1 earthquake that killed more than 300 people in September. But recently, a new hypothesis has emerged: Perhaps most of the Guerrero gap’s pressure has already been relieved by puzzling “slow slip events,” in which swaths of Earth’s crust shift by several centimeters—not in seconds, as in ordinary earthquakes, but over weeks or months.

Six papers by disgraced surgeon should be retracted, report concludes

Sweden’s national scientific ethics board, the Expert Group on Misconduct in Research, has concluded that six papers authored by disgraced surgeon Paolo Macchiarini should be retracted. The papers describe the purported clinical success of artificial tracheae “seeded” with a patient’s own stem cells. All three patients described in the papers died of complications related to the implant.

New great ape species found, sparking fears for its survival

Researchers have identified the first new species of great ape since 1929: an orangutan that lives in an isolated forest on the Indonesian island of Sumatra. Fewer than 800 individuals remain, making it one of the world’s most endangered great apes. What’s more, the caterpillar-loving orangutans may soon face a new threat—a proposed dam and road that could destroy their prime habitat.

Announcing the winner of this year’s ‘Dance Your Ph.D.’ contest

It’s not enough to do good research. You have to communicate it—and sometimes you need to pull out science’s most powerful and top-secret communication tool: interpretive dance. That’s what mathematician Nancy Scherich did to win this year’s Science/AAAS 10th annual “Dance Your Ph.D.” contest. Scherich, from the University of California, Santa Barbara, created a dance to explain her Ph.D. research with aerial silk acrobatics and glowing hula hoops. (Spoiler alert: It involves linear algebra and murder!) Other winners use dance to explain their work on sea star ecology, the psychology of creativity, and the biochemistry of criminal forensics, which also won our online audience favorite award.