Look Who's Driving

After years of anticipation, autonomous vehicles are now being tested on public roads around the world. As ambitious innovators race to develop what they see as the next high-tech pot of gold, some experts warn there are still daunting challenges ahead, including how to train artificial intelligence to be better than humans at making life-and-death decisions. How do self-driving cars work?

To test self-driving cars without putting lives at risk, most companies do a lot of their training in environments they can fully control. But ultimately, the only way to know how a car will perform on public roads is to test it in the real world.