What is the universe made of? If you answered stars, planets, gas and dust, you'd be dead wrong. Thirty years ago, scientists first realized that some unknown dark substance was affecting the way galaxies moved. Today, they think there must be five times as much dark matter as regular matter out there. But they have no idea what it is — only that it's not made of atoms, or any other matter we are familiar with. And Dark Matter is not the only strange substance in the Universe — a newly discovered force, called Dark Energy, seems to be pushing the very fabric of the cosmos apart.

The episode was rated 7.91 from 222 votes.

Genius lies somewhere in the human mind, bringing mathematical insight, sparking artistic inspiration and enabling some to see what most cannot. Might we augment our biology with technology to unlock the genius inside us all?

The episode was rated 7.92 from 136 votes.

Scientists are peering inside the mechanisms of aging, tampering with the cellular makeup of our DNA, and imagining a world where death is cured like a disease. Are we entering a new age of immortality? Or is dying necessary for our race's survival?

The episode was rated 7.93 from 126 votes.

It's called the speed limit of the universe. Einstein blew all of our minds when he worked out the Theory of Relativity, and showed that space and time were malleable substances. He also theorized that we as humans can never travel faster than the speed of light, which leaves the stars and other galaxies almost impossibly out of our reach. But the dreams of Star Wars and Star Trek are not dead. In fact, there could be ways to travel faster than the speed of light - and some of them are already being tested in labs around the world.

The episode was rated 7.94 from 177 votes.

How different are the races? Is there even such a thing as race? Could technology create a superior race? The answer may tell us where humanity is headed, what our descendants will look like and how they will think.

The episode was rated 7.96 from 140 votes.

It is commonly theorized that the universe began with the Big Bang 13.7 billion years ago. But since we can only see as far as light has traveled in that time, we can't actually make out the edge of the universe. Could it be that the universe is infinite? Is there any way to find out what the shape of the universe really is? Can we find the edge, discover what might lie beyond it, and perhaps even discover a universe next to ours?

The episode was rated 7.97 from 224 votes.

We feel it every moment of our lives but for physicists, gravity is the longest running unsolved mystery of the universe. Why do all objects that have mass pull on one another? Cutting-edge theories are proposing unexpected answers: Gravity could be another force in disguise, a thermodynamic mirage, or even, a shadow of a hidden holographic universe. If so, the force that holds us to the surface of the earth, and holds the earth in orbit around the sun, may be a trick of the mind. We feel it, but it may not be real. Is Gravity an Illusion?

The episode was rated 8.01 from 154 votes.

We are all at the mercy of the Sun. Its glowing disc sustains nearly all life on Earth. But the Sun also holds a dark secret: someday, our aging, expanding star will bathe the Earth in a fiery holocaust. Everything we know will turn to hot, bubbling, plasma.

The episode was rated 8.02 from 156 votes.

What drives some to torture and kill without remorse? Why do seemingly normal people commit acts of cruelty and violence. Researchers are exploring our inner demons, looking for ways to isolate and neutralize the source of evil in the brain. Is it really possible to change human nature?

The episode was rated 8.02 from 133 votes.

Mankind longs for proof that we are not alone in the universe, but the moment of first contact will certainly mean the end of the world as we know it. Whether that is a bad thing for humanity or the start of a great future is uncertain.

The episode was rated 8.04 from 183 votes.

Our understanding of the universe and the nature of reality itself has drastically changed over the last 100 years, and it's on the verge of another seismic shift. In a 17-mile-long tunnel buried 570 feet beneath the Franco-Swiss border, the world's largest and most powerful atom smasher, the Large Hadron Collider, is powering up. Its goal is nothing less than recreating the first instants of creation, when the universe was unimaginably hot and long-extinct forms of matter sizzled and cooled into stars, planets, and ultimately, us. These incredibly small and exotic particles hold the keys to the greatest mysteries of the universe. What we find could validate our long-held theories about how the world works and what we are made of. Or, all of our notions about the essence of what is real will fall apart.

The episode was rated 8.04 from 211 votes.

We are in the midst of a revolution so insidious we can't even see it. From our telephones to our vacuum cleaners to our cars, we have robots that live and work beside us. And now we're designing them to think for themselves, giving them the power to learn to move on their own.

The episode was rated 8.05 from 144 votes.

It is a question that has vexed philosophers and scientists for centuries; 'What is Time?' Exactly how is our past, present, and future connected by that arrow of cause and effect that we call Time? Is time simply another dimension, just like the dimensions of space we know? Can you run time backwards just as easily as it runs forward, just as left-to-right can swap for right-to-left? If other universes exist, then what is time like in them: could their Time be different from ours? And we'll probe the biggest question about time: Is our future determined? Do we exercise free will? Or, is time merely a dream?

The episode was rated 8.07 from 192 votes.

Scientists explore the effects of the Higgs Boson discovery, which validates the Standard Model in particle physics and solidifies the understanding of subatomic particles; highlights include an in-depth discussion of the Higgs field and mass.

The episode was rated 8.07 from 163 votes.

Medical advances have doubled human life expectancy in past centuries. But can humans ever beat death altogether? Can we control and fix the errors that build up in our DNA over the years? Can we find a way to replace the chemistry of life with something more durable? This episode wonders into the mystifying definition of 'eternity' as it relates to human lifespan.

The episode was rated 8.07 from 134 votes.