Taylor Wilson never just got interested in things.

"He got obsessed," says his father, Kenneth. "Whatever he was involved in, he went at it nonstop. Even getting him to eat was a big trick. Sometimes it still is."

In elementary school in Texarkana, Arkansas, Taylor hopscotched exuberantly from one infatuation to the next—biology and genetics, then chemistry, then rocketry. Next came nukes: When Taylor was 11 he tried to build his first particle accelerator—an atom smasher—to transmute elements and create homemade radioisotopes.

At 14, he succeeded in building a working reactor that could fling atoms together in a plasma core at 500 million degrees Fahrenheit, becoming the youngest individual to achieve nuclear fusion. Now 19, he's developing new ways to use subatomic particles to confront some of the biggest challenges of our time: cancer, nuclear terrorism, and energy.

I caught up with Taylor in mid-March as he was on his way back from a TED conference in Vancouver. For many professionals, an invitation to talk at TED is a career-defining moment, an acknowledgment that a person has "arrived" in the world of big ideas. But Taylor, who first spoke on the TED stage at 17, is now a veteran, with three TED presentations under his belt.

When I asked him how much he'd prepared for this year's talk, he laughed.

"Last year I prepared, and it was the first time I'd ever prepared for a talk in my life," he says. "I think it came off a little stilted. This year, I went back to the way I handled my first TED talk: I winged it."

View Images Taylor, seen here in his garage in Reno, Nevada, built a nuclear reactor when he was 14 in the basement of the University of Nevada physics lab. PHOTOGRAPH BY DEANNE FITZMAURICE, NATIONAL GEOGRAPHIC

Scientific pursuits often tend to draw introverts. That has left the scientific community with a shortage of effective communicators—to the detriment, some say, of persuasive policymaking on important issues such as climate change. But Taylor challenges "science nerd" stereotypes. He's highly social and exuberantly connected to the universe around him. His gift for making connections—personal, intellectual, practical—has allowed him to build a life for himself that seems to lack limits. "Within two minutes of meeting him," says nuclear security expert Stephen Younger, an early mentor, "you realize that the kinds of things that most people think are impossible, Taylor just goes out and does."

"Star in a Jar"

When Taylor was in the fifth grade, he read The Radioactive Boy Scout, a book by Ken Silverstein, which told the story of a teenager in suburban Detroit who, in the mid-1990s, attempted to build a nuclear breeder reactor in a backyard shed—an endeavor that resulted in a Superfund cleanup of the contaminated site.

"What was intriguing to me was that I had thought this stuff was out of reach, that it was the domain of only the big labs and researchers with big budgets and advanced degrees," Taylor says. "That a kid could get involved with hands-on nuclear physics was revelatory. I thought, assuming I didn't make the mistakes he did, I could do what he was trying to do—but I could be the responsible radioactive Boy Scout." Though his parents were at first wary, his elementary school's science fair gave Taylor an opportunity to ease into nuclear science, with a survey of harmless everyday radioactive materials.

When he was 11, after his maternal grandmother's cancer came out of remission, Taylor had a brainstorm: What if there were a way to make medical isotopes at or near the patients? Instead of creating the radioactive materials to diagnose and treat cancer in multimillion-dollar cyclotrons and then rushing them across the continent, what if he could build a reactor—driven by the same nuclear-fusion process that powers the sun—small enough, cheap enough, and safe enough to irradiate materials for medical isotopes as needed, in every hospital in the world? How many more people like his grandmother could they reach, and how much earlier could they reach them?

But the process of building a "miniature star"—a machine that can accelerate particles at speeds and temperatures high enough to fuse atoms—on Earth is extraordinarily complex, the kind of project that labs and governments spend tens of billions of dollars on. To create his own "star in a jar," Taylor would need to master at least 20 scientific and engineering fields, including nuclear and plasma physics, chemistry, radiation metrology, and electrical engineering. He would need to design and build a device that could create and hold a vacuum several powers of magnitude beyond the vacuum of outer space. He would also need to concentrate up to 100,000 volts of electricity to accelerate atomic particles at speeds and temperatures high enough to fuse their nuclei together and release their energy.

View Images Taylor's nuclear reactor is now in his lab at University of Nevada, Reno. PHOTOGRAPH BY DEANNE FITZMAURICE, NATIONAL GEOGRAPHIC

Taylor's parents supported his unusual avocation, helped him find mentors, and even relocated the family to Reno, Nevada, so that he and his brother could attend a public school for profoundly gifted children. With the help of supportive professors and technicians in the University of Nevada's physics department, Taylor built his "fusor" and entered it in the Intel International Science and Engineering Fair, the "Super Bowl" of precollege science events.

Over the next four years, Taylor won more than a dozen awards (including the top award in physics and the Intel Foundation Young Scientist Award) for his fusion-based applications for medical isotopes and weapons-detection systems. When Intel CEO Paul Otellini heard the buzz that a 14-year-old had built a working nuclear-fusion reactor, he went straight for Taylor's exhibit. Later, he remarked, "All I could think was, 'I am so glad that this kid is on our side.'"

"Doing Things for Bigger Reasons"

Taylor's scientific pursuits have since taken him to the White House and around the world. In 2012, he accepted a Thiel Fellowship, a no-strings-attached grant of $100,000 that lets gifted kids ages 19 and under forgo college and focus on their work, their research, and their self-education. Taylor will concentrate on building a business to bring some of his inventions to market.

"It was a huge decision," he says. "I knew the lack of the social aspect of college might be challenging, and it has been. I've had to work hard to create my own community," which he has done by visiting high school friends at their campuses and engaging with all sorts of people at conferences.

Now that Taylor is an adult, has his approach to science changed?

"I've been into science all my life, and at first I was exploring things because I was interested in them. It was fun, but in a way it was selfish too. Then it turned out that I was really good at it, and it became a responsibility. I realized I had the capability of doing things that could really change the world. So now I'm doing things for bigger reasons. It's still fun, but there's that responsibility on top of it."

Taylor's early successes defined him as a child prodigy, a "boy genius."

"I always tried to shunt off those labels; they kind of bothered me," he says. "But now I see that kids sometimes have an advantage when it comes to invention. Their lack of experience can actually be a benefit, because they have a less constricted view of the world. Older scientists, in their professional careers, sometimes get in this mentality that it can't be done or you shouldn't even try it, whereas kids are not so closed-minded. They can see things in ways that adult scientists often can't.

"Hopefully I'll never have to grow up too much," he says. "Because what makes really good scientists is a healthy disregard for limits and conventions that say 'you can't do this or that.' I hope I never lose that."