Ray Kurzweil is teaching computers how to read better—one more step in the march of technological progress. The 66-year-old inventor and futurist thinks that by 2030, computers won't only be able to understand ordinary spoken language but will show emotions too. Next to arrive will be the "singularity"—a term he popularized nearly a decade ago for the point at which humans and computers will merge as one. That will happen in 2045, he predicts, when human intelligence will be enhanced a billion-fold thanks to high-tech brain extensions.

For now, as a director of engineering atGoogle, a role he started in January 2013, Mr. Kurzweil is primarily working on getting machines to understand what scientists call "natural" language. Computers aren't as good as humans at context. Today, for example, a computer might scan the words in a news article and conclude that there is a 56% chance that Barack Obama is the president of the U.S. But a human would read the same article and determine the same thing with near certainty. Mr. Kurzweil is developing software that he hopes will enable computers to understand language conceptually, rather than just by key words—with the near-term goal of creating a better, more conversational search function for Google.

His latest effort follows a long career in technology. Growing up in New York City, he decided at age 5 that he wanted to become an inventor. He went on to graduate from the Massachusetts Institute of Technology, where he started his first software company as a sophomore.

Since then, he has launched several companies and invented the first print-to-speech reading machine for the blind, among other breakthroughs. He has become especially well-known for his books on artificial intelligence, such as "The Age of Spiritual Machines" (1999) and "The Singularity Is Near" (2005).

His latest book is "How to Create a Mind," published in 2012. In it, he advocated building a synthetic extension of the brain—connecting it to the cloud. He thinks that nanobots will one day travel to our brains through our capillaries and that blood-cell-sized computers will connect to the cloud the way our iPhones do now.

While that is still decades away, Mr. Kurzweil is trying to get computers to simulate the brain's natural thought process. Before the publication of "How to Create a Mind," he met with Google chief executive Larry Page to give him a copy and pitch him on investing in a company he wanted to create based on the ideas in his book. Mr. Page was interested but instead persuaded Mr. Kurzweil to start it at Google, having the use of the company's resources but keeping his independence intact. (Since then, Google has continued building a veritable artificial intelligence laboratory, hiring artificial-intelligence researcher Geoffrey Hinton and recently acquiring the company DeepMind, which combines techniques from machine learning and neuroscience to build algorithms.)

Talking in his West Coast apartment, Mr. Kurzweil is quick to add that Google isn't working on brain nanobots. But he imagines that once our neocortex's are connected to the cloud—something he expects will happen in the 2030s—this wireless connection will make us much smarter. "Somebody's approaching and I need to think of something clever, and if my neocortex doesn't cut it, I'll be able to access more neocortex in the cloud," he says.

Some of his other ideas have hit the mainstream recently. Spike Jonze, the director of "Her," has said that the 2013 movie was inspired by Mr. Kurzweil's writings. Still, Mr. Kurzweil found some fault in the film's development of the futuristic operating system, voiced by Scarlett Johansson. With her level of emotional understanding, he says, she also should have had a virtual body.

Mr. Kurzweil is also concerned with matters of a more strictly biological nature. He has written three books on health and nutrition, co-founded a company that sells "longevity products" like supplements and has long been fascinated with radical life extension. He thinks that humans will one day be able to live indefinitely, but first we must cross three "bridges."

The first of these is staying healthy much longer. To that end, the smooth-skinned and youthful Mr. Kurzweil consumes 120 vitamins and supplements every day, takes nutrients intravenously (so that his body can absorb them better), drinks green tea and exercises regularly. That regimen keeps his "real age" in the 40s, he says.

The second bridge is reprogramming our biology, which began with the Human Genome Project and includes, he says, the regeneration of tissue through stem-cell therapies and the 3-D printing of new organs.

We will cross the third and final bridge, he says, when we embed nanobots in our brains that will affect our intelligence and ability to experience virtual environments. Nanobots in our bodies will act as an extension of our immune system, he says, to identify and destroy pathogens our own biological cells can't.

Mr. Kurzweil projects that the 2030s will be a "golden era," a time of revolution in how medicine is practiced. He compares the human body to a car. "Isn't there a natural limit to how long an automobile lasts?" he asks. "However, if you take care of it and if anything goes wrong, you fix it and maybe replace it, it can go on forever." He sees no reason that technology can't do the same with human parts. The body is constantly changing already, he says, with cells replacing themselves every few days to months.

His vision of the future raises the question of what it means to be human. Yet he believes that adding technology to our bodies doesn't change our essence. "The philosophical issue of identity is, 'Am I the same person as I was six months ago?' " he says. "There's a continuity of identity."

In some ways, we've already expanded our brains, he says. When it comes to mobile devices like smartphones, for instance, "philosophically I don't see a significant difference whether [technology] is inside your brain or whether my brain is directing my fingers," he says. "It's really an extension of my brain already, but we will make it more convenient by directly connecting it into our brains."

"Remember what happened the last time we expanded our neocortex?" he asks. "That was two million years ago, when we became humanoids and developed these large foreheads, whereas other primates have a slanted brow." This time around we won't be limited by physical constraints. As a result, he says, "we'll think deeper thoughts, we'll have more beautiful music, and we'll have deeper relationships."

Mr. Kurzweil believes that our thinking will eventually be a hybrid of the biological and the nonbiological. "I would say humans are not purely biological," he says. "We've already expanded humanity with our technology, and the technology is part of humanity; we are the technology."

Mr. Kurzweil is well aware of the darker side of a more technological future. "Technology has always been a double-edged sword," he says. Fire has helped humans improve their lives, but it also burns down villages. And while he thinks technology can reprogram our biology away from disease, it can also fall into the hands of terrorists who might reprogram colds into deadly viruses. ("We're not defenseless against that," he adds, having spent time helping the U.S. Army come up with a program to combat biological threats.) And he's reassured by the ubiquity of networked technology. With smartphones in the hands of billions of people, crowds can organize to deal with many problems.

The futurist is unabashed about his positive outlook. "I'm accused of being an optimist, and I am," he says. "It's not a naive optimism, though." He has thought extensively about the possible dangers ahead, he says, and thinks "we have to give very high priority to managing the downside."

In any case, Mr. Kurzweil plans to be around to see whatever the future holds. "The goal is to live indefinitely," he says. As a backup plan, he will cryogenically preserve his body. But, he says, "the goal is not to need to."