But the qualitative impact will be even bigger. Right now, maybe 10,000 or 20,000 people have ever ridden in a self-driving car, in any context. Far fewer have been in a vehicle that is truly absent a driver. Up to a million people could have that experience every day in 2020.

2020 is not some distant number. It’s hardly even a projection. By laying out this time line yesterday, Waymo is telling the world: Get ready, this is really happening. This is autonomous driving at scale, and not in five years or 10 years or 50 years, but in two years or less.

When Waymo starts to hit the big numbers, it will be a watershed moment not just for self-driving cars but for artificial intelligence in general. If people suddenly have thousands of robots driving among them, what else will they become comfortable—or uncomfortable—with robots doing?

At the same time, the questions that Waymo needs to answer are changing. Up to this point, the primary point of emphasis among journalists and other interested observers has been technological: Does the self-driving car work?

And there are subsidiary questions that run down from there: Which sensors create the best data? How is that data integrated into a model of the world? What algorithms are best for choosing a route? What kinds of tests generate the most useful new data? What simulation software can accelerate real-world learning the fastest? What are the modes of failure?

These are the questions that the killing of a pedestrian in Arizona by an Uber self-driving vehicle has raised with new intensity. No self-driving car should have missed that pedestrian crossing the road. For whatever version of Uber’s self-driving system that was being tested that day, the answer to the question “does it work?” was a simple no.

But for Waymo’s program, that line of questioning is becoming a red herring. Waymo is not spending a billion dollars on cars for a fleet because they are not sure if their technology works. It works well enough to begin rolling it out to a million people a day. Waymo cars will most certainly get in accidents. They will kill people, too. But everything about Waymo’s program suggests that they think their cars are substantially safer than human drivers.

For years, people asked questions of Facebook that were about their technology and business. Can it scale? Will they be able to monetize? But when it turned out that, yes, it could scale, and yes, they would have 75 percent gross margins, the next set of questions had not received proper attention. For example, what does rewiring the world’s political systems through Facebook mean for democracies? What should Facebook’s relationship to political candidates and governments be?

It wasn’t that scholars and journalists hadn’t asked the questions, but the vast majority of people reacted to the technology as consumers (or purchasers of stocks), not as citizens.