Rather than create electricity by heating water and turning a turbine, Wilson's new reactor would use nuclear fission to produce energy from molten salt. His plan would be to centrally manufacture small fission reactors and distribute them widely for burial underground. He said they could last for 30 years without refueling, compared with 18 months for larger commercial reactors.

Since the reactors would not be pressurized, radioactivity would not be expelled as widely into the environment as in an accident like the Fukushima disaster, Wilson said. Costs would be lower since reactors would not have to be built onsite. Nuclear weapons could be recycled in the reactor, he said. And most exciting to the young space geek, such a reactor could power a spaceship to a distant planet and then be the power source for a human base at the destination, he said.

Andraka, who's 16 and a high school sophomore, won the top prize in the Intel Science Fair competition for his cancer screening test, which relies in part on carbon nanotubes to detect a protein that is present in the blood and urine in the early stages of the three deadly cancers, providing hope that they can be detected in time for a successful cure.

He told CNN in an interview that he doesn't go to high school much anymore but is busy with other projects -- including inventing an MRI the size of a credit card and leading a team of high school students competing for the $10 million Tricorder X Prize to design a handheld device people could use to monitor their health.

Andraka and Wilson probably don't have to worry about it but another speaker added a sobering element to the celebration of youth at TED. Meg Jay, a psychologist and author, argued against the idea that the 20s are a period of extended adolescence where people can postpone key life choices. By the time people reach 30, they may have missed out on some key chances to take their life in the directions they hope to pursue. "Thirty is not the new twenty," she said, urging people to "claim your adulthood" and start making choices.

Spoken word poet Shane Koyczan, a 36-year-old whose new video "To This Day" has attracted 5.5 million views, offered a reminder that for all that young people can achieve, many still carry a heavy burden. He told of being bullied as a child to the point that, without realizing it, he turned into a bully himself. He spoke of kids being called names, making them feel like "oddities juggling depression and loneliness" and challenged them:

"if you can't see anything beautiful about yourself

get a better mirror

look a little closer

stare a little longer

because there's something inside you

that made you keep trying

despite everyone who told you to quit"