When I played that clip again on Google's blog post later, my wonder turned to unease. I dissected that conversation, analyzing all the ways that the AI mimicked human behavior. Its methods, I discovered, were incredibly sophisticated. It didn't just insert random pauses or nonverbal sounds, but did so in places that made sense. And even the way it said things like "Ohh, I gotcha," were so lifelike they were laden with meaning and subtext. Assistant conveyed rich, high-context information in simple sentences, just as we humans do -- with sarcasm and ambiguity. How did it get so creepily real?

It's been a year since CEO Sundar Pichai declared the intention to shift focus from "mobile first" to "AI first." Since then, Google has invested heavily in machine learning research, developing frameworks to create more sophisticated applications that can basically think for themselves.

There's no denying Google's pivot to AI has brought some truly useful new features. Photos, for one, can identify the exact outline of a subject like your adorable toddler, and turn everything else in the picture grayscale to make a stylized picture. Or it can take an old black-and-white photo, identify the trees or the grass and colorize them appropriately. Meanwhile, the revamped News app will use AI to pick a variety of sources to deliver full, rounded perspectives on news stories. Smart Replies, which debuted in Inbox as early as 2015, and its logical extension Smart Compose, can save you the trouble of coming up with answers to your friends' inane emails. In every one of Google's vast array of products, AI has been inserted to improve performance and utility. They're getting smarter and faster at understanding not just context but also our preferences and behaviors, meaning we can think less, and let the computers do that for us.

With Duplex, Assistant will be able to book restaurants and services for you via a phone call. Simply ask it to make you a haircut appointment on Tuesday between 10am and noon, for example, and Assistant will call your designated salon and sort out your reservation. It's like having a real-life personal assistant, and if Google pulls this off, the convenience it offers would be immense.