In June, at a conference set in the picturesque Italian town of Campagna, south-east of Naples, two physicists in a seemingly endless argument over a long-sought theory of fundamental reality caught my attention. From the sidelines, an unassuming figure politely interrupted them. "I've got a slide that might help. Can I put it up?" asked Frank Wilczek. The slide, concisely describing the realms in which this theory may act, swiftly ended the dispute.

In a preprint posted online Thursday night, researchers at Google in collaboration with physicists at Stanford, Princeton and other universities say that they have used Google's quantum computer to demonstrate a genuine "time crystal." In addition, a separate research group claimed earlier this month to have created a time crystal in a diamond. A novel phase of matter that physicists have strived to realize for many years, a time crystal is an object whose parts move in a regular, repeating cycle, sustaining this constant change without burning any energy. "The consequence is amazing: You evade the second law of thermodynamics," said Roderich Moessner, director of the Max Planck Institute for the Physics of Complex Systems in Dresden, Germany, and a co-author on the Google paper. That's the law that says disorder always increases.

In his Wall Street Journal column this weekend, Nobel laureate Frank Wilczek offers a fascinating theory as to why we haven't been able to find signs of intelligent life elsewhere in the universe. Maybe, he suggests, intelligent beings are fated to shrink as their intelligence expands. Once the singularity happens, AI implodes into invisibility. Wilczek notes that "effective computation must involve interactions and that the speed of light limits communication." To optimize its thinking, an AI would have no choice but to compress itself to minimize delays in the exchange of messages.

Look! Up in the sky! Is it a bird or is it a plane? If you're in Nevada, it could be the world's first passenger drone. The electric Ehang 184-passenger drone has been given clearance for testing in the airspace above the Silver State, the Guardian reported Wednesday. The drone can carry people inflight for 23 minutes.

The world's first passenger drone capable of autonomously carrying a person in the air for 23 minutes has been given clearance for testing in Nevada. Chinese firm Ehang, which unveiled the electric Ehang 184 passenger drone at CES in Las Vegas in January, has partnered with the Nevada Institute for Autonomous Systems (NIAS) and the Governor's Office of Economic Development (Goed) to put the drone through testing and regulatory approval. Tom Wilczek, Goed's aerospace and defence specialist said: "The State of Nevada, through NIAS, will help guide Ehang through the Federal Aviation Authority (FAA) regulatory process with the ultimate goal of achieving safe flight." The founder and chief executive of Ehang, Huazhi Hu, said the move would lay the foundation for the 184's commercialisation and kickstart the autonomous aerial transportation industry. Ehang hopes to begin testing later this year and will have to prove airworthiness to the FAA, with guidance from NIAS, before being able to operate in a wider capacity.