We share the planet with an estimated 9 million robots, from self-driving cars to surgical arms. Could they one day completely replace humans?

The episode was rated 7.15 from 105 votes.

Fifteen international agencies spend $62 billion every year on space travel. What's fueling our costly — and dangerous — drive to explore the universe?

The episode was rated 7.18 from 145 votes.

A groundbreaking medical reproductive procedure has made parenthood possible for millions around the world... but at what cost?

The episode was rated 7.30 from 46 votes.

The home fitness revolution has exploded into a multibillion-dollar industry. Are home workouts a healthy habit... or just hype?

The episode was rated 7.36 from 44 votes.

Over 10% of the world's electricity comes from nuclear power. But with radioactive waste and the threat of nuclear meltdown, are we playing with fire?

The episode was rated 7.37 from 100 votes.

Growing evidence suggests that psychedelic drugs could treat brain injuries and psychological problems. But can we get past their controversial history?

The episode was rated 7.40 from 55 votes.

DNA analysis has given us the tools to map disease, solve crimes and more. But in our rush to decode DNA, are we leaping before we look?

The episode was rated 7.43 from 98 votes.

They're used for everything from entertainment to medicine — and now for weapons straight out of science fiction. Have lasers become too hot to handle?

The episode was rated 7.44 from 48 votes.

In the 21st century, China has become a global economic powerhouse. Why was the rest of the world so slow to notice its rise to the top?

The episode was rated 7.44 from 138 votes.

Plastics have transformed how we live, but progress comes at a high price: 7.8 billion tons of waste. Are plastics a miracle or a catastrophe?

The episode was rated 7.46 from 112 votes.

Sweet deal or bitter pill? High fructose corn syrup rose up to dominate supermarket shelves, but what is it doing to our health?

The episode was rated 7.46 from 50 votes.

Credit cards changed the global economy and attitudes about personal spending, but record levels of consumer debt beg the question: Just who's in charge?

The episode was rated 7.72 from 50 votes.

MP3s transformed how we listen to music — and spawned digital piracy. Streaming helped the industry recover, but how can artists get their fair share?

The episode was rated 7.84 from 49 votes.

Once a secret military program, GPS now guides our daily lives, from providing directions to finding friends. But what do we trade for this convenience?

The episode was rated 7.89 from 54 votes.

Bottled water is a big business, selling itself as a tastier and healthier alternative to the tap variety. Is there truth behind the claims?

The episode was rated 7.94 from 48 votes.