Megalithic monuments in the otherworldly Orkney Islands remain a fundamental part of the landscape. Sheep linger at the Stones of Stenness, the remnants of a ceremonial circle. The Stones of Stenness, a brood of lichen-encrusted megaliths in the far north of the British Isles, could be mistaken for a latter-day work of land art, one with ominous overtones. The stones stand between two lochs on the largest of the Orkney Islands, off the northeastern tip of mainland Scotland. Three colossal planks of sandstone, ranging in height from fifteen feet nine inches to eighteen feet eight inches, rise from the grass, along with a smaller stone that has the bent shape of a boomerang. In contrast to the rectilinear blocks at Stonehenge, the Stenness megaliths are thin slabs with angled upper edges, like upside-down guillotine blades. Remnants of a ceremonial circle, they are placed twenty or more feet apart, creating a chasm of negative space. The monoliths in "2001: A Space Odyssey" inevitably come to mind. Given that the stones were erected five thousand years ago by a culture that left no trace of its belief system, it is unwise to project modern aesthetics onto them. Still, they can be seen only with living eyes. During a recent visit to Orkney, I kept returning to Stenness, at all hours and in all weather. On drizzly days, with skies hanging low, the stones resemble ladders to nowhere. In bright sun, hidden colors emerge: streaks of blue against gray; white and green spatters of lichen; yellowish stains indicating the presence of limonite, an iron ore. Pockmarks and brittle edges show the abrading action of millennia of wind and rain. I watched as tourists approached the stones and hesitantly touched them, as if afraid. When I put my own hands on the rock, I felt no obvious emanations, though I did not feel nothing. One evening, I leaned on a fence as the sun went down, the horizon glowing orange against a cobalt sky.

Whether due to consumer backlash or an aging EV lineup, or both, Tesla sales have again seen a global plunge, this time 13 percent last quarter compared to the previous year--proof that the electric automaker hasn't yet turned around a dismal year that saw public opinion of controversial CEO Elon Musk plummet. It could mean Tesla faces a second straight year of falling sales. And yet: Tesla is still the world's most valuable automaker by market capitalization, worth some 990 billion. At least some of that market confidence is likely traced to the happenings of June 22, when Tesla finally began allowing paying passengers to ride its autonomous vehicle service in Austin, Texas. The service rollout has been fairly smooth.

Marking the end of a longtime tradition, the Fourth of July celebration at the Rose Bowl in Pasadena will not feature a fireworks show this year. Instead, there will be a drone show. The move comes as some venues have switched from fireworks to drone shows -- in which a fleet of drones performs a choreographed light show -- to celebrate the 4th of July. But drone shows have fallen flat for some. Notably Redondo Beach and Laguna Beach switched back to fireworks after trying out drone shows, and some promoters of fireworks shows have voiced criticism over efforts to transition to drone shows.

It is a significant overhaul of a department that in 40 years has never before been placed so squarely on the chopping block. Here's how today's defense tech companies, which have fostered close connections to the Trump administration, stand to gain, and why safety testing might suffer as a result. The Operational Test and Evaluation office is "the last gate before a technology gets to the field," says Missy Cummings, a former fighter pilot for the US Navy who is now a professor of engineering and computer science at George Mason University. Though the military can do small experiments with new systems without running it by the office, it has to test anything that gets fielded at scale. "In a bipartisan way--up until now--everybody has seen it's working to help reduce waste, fraud, and abuse," she says.

We study a fundamental learning problem over multiple groups with unknown data distributions, where an analyst would like to learn the mean of each group. Moreover, we want to ensure that this data is collected in a relatively fair manner such that the noise of the estimate of each group is reasonable. In particular, we focus on settings where data are collected dynamically, which is important in adaptive experimentation for online platforms or adaptive clinical trials for healthcare. In our model, we employ an active learning framework to sequentially collect samples with bandit feedback, observing a sample in each period from the chosen group. After observing a sample, the analyst updates their estimate of the mean and variance of that group and chooses the next group accordingly. The analyst's objective is to dynamically collect samples to minimize the collective noise of the estimators, measured by the norm of the vector of variances of the mean estimators. We propose an algorithm, Variance-UCB, that sequentially selects groups according to an upper confidence bound on the variance estimate. We provide a general theoretical framework for providing efficient bounds on learning from any underlying distribution where the variances can be estimated reasonably. This framework yields upper bounds on regret that improve significantly upon all existing bounds, as well as a collection of new results for different objectives and distributions than those previously studied.

The number of pedestrian deaths in the United States is skyrocketing. In 2022 traffic crashes killed 7,805 people on foot--that's an 83 percent rise from 2009, and a 40-year high. The vast majority of those deaths involved a car colliding into a human. In September, the National Highway Traffic Safety Administration took a significant step toward addressing the crisis of killer cars, proposing a new federal rule that would require--not ask--carmakers to ensure that the front ends of their vehicles do not create excessive risk of pedestrian head injuries. Should the proposal become law, hulking SUVs and pickups would face particular challenges passing NHTSA's mandatory tests.

One of the largest accident studies yet suggests self-driving cars may be safer than human drivers in routine circumstances – but it also shows the technology struggles more than humans during low-light conditions and when performing turns. The findings come at a time when autonomous vehicles are already driving in several US cities. The GM-owned company Cruise is trying to restart driverless car testing after a pedestrian-dragging incident in March led California to suspend its operating permit. Meanwhile, Google spin-off Waymo has been gradually expanding robotaxi operations in Austin, Los Angeles, Phoenix and San Francisco. "It is important to improve the safety of autonomous vehicles under dawn and dusk or turning conditions," says Shengxuan Ding at the University of Central Florida.

The UK's Advanced Research and Invention Agency (ARIA) has chosen eight scientists who will each be given up to £50 million to allocate as they see fit, in the hopes that a high-risk, high-reward approach to research funding will deliver results that benefit UK society and fuel economic growth. ARIA is the brainchild of Dominic Cummings, an adviser to former UK prime minister Boris Johnson who has long wanted to shake up UK science funding. "A small group of people can make a huge breakthrough with little money but the right structure, the right ways of thinking," Cummings wrote in 2017. He was inspired by the US's Advanced Research Projects Agency (ARPA), which spurred computer science as a discipline and created a forerunner of the internet in the 1960s and 1970s. It did this, in the words of one of its leading scientists, by having "visions rather than goals" and because it "funded people, not projects".

This week, US senators heard alarming testimony suggesting that unchecked AI could steal jobs, spread misinformation, and generally "go quite wrong," in the words of OpenAI CEO Sam Altman (whatever that means). He and several lawmakers agreed that the US may now need a new federal agency to oversee the development of the technology. But the hearing also saw agreement that no one wants to kneecap a technology that could potentially increase productivity and give the US a lead in a new technological revolution. Worried senators might consider talking to Missy Cummings, a onetime fighter pilot and engineering and robotics professor at George Mason University. She studies use of AI and automation in safety critical systems including cars and aircraft, and earlier this year returned to academia after a stint at the National Highway Traffic Safety Administration, which oversees automotive technology, including Tesla's Autopilot and self-driving cars.

On Wednesday the National Highway Traffic Safety Administration announced a massive recall of Teslas equipped with Full-Self Driving Beta, the technology that enables vehicles to control aspects of driving, such as turning and adjusting speed, in urban environments. The FSD package, which currently costs Tesla owners an additional $15,000 when they buy their cars, requires the driver to be watching the road at all times (although Tesla enthusiasts have figured out ways to trick the cars' attention guardrails for years). The NHTSA recall affects over 360,000 Teslas with FSD, which is pretty much all of them. Critics have long warned that FSD is dangerous, and the recall's language suggests they were right. According to NHTSA, FSD "may allow the vehicle to act unsafe [sic] around intersections, such as driving straight through an intersection while in a turn-only lane."