With cloning and genetic engineering, we can bring back extinct animals. But could we also bring back dead humans? Is it possible to keep our brains alive after our bodies have died? Could we rise from the dead in some strange new form? Can we - should we - resurrect the dead?

The episode was rated 7.75 from 134 votes.

Does your subconscious know more than you ever will, and is your conscious mind holding you back? Do thoughts control actions, or vice versa? Research shows that opening the subconscious may make people healthier and more creative. There are also dangers lurking in the dark recesses of the mind.

The episode was rated 7.76 from 146 votes.

Many religious traditions have predicted that our world will come to an apocalyptic end. Scientists agree that Earth can't last forever, but disagree on whether the universe and time itself can ever disappear. Some may hope for eternity, but the possibility of never-ending time has mind-bending implications for the present.

The episode was rated 7.78 from 129 votes.

As scientists peer across the galaxy, a new revelation emerges: The universe is shockingly organic. Are the secrets to the life and death of the universe hidden not in physics, but biology? Could it be that the universe is alive?

The episode was rated 7.78 from 151 votes.

Our belief in a God above explains all we can't understand. Where do religious beliefs come from? Some experts believe God may exist only in our brain, that we are wired to worship the supernatural and that faith in a higher power gives us an evolutionary advantage. Is it possible that God is really just a neurological accident? And does that make Him any less real? Did God invent humanity, or did humanity invent God?

The episode was rated 7.87 from 133 votes.

Is empty space really empty? Scientists regard understanding the true nature of empty space may explain where the universe came from, whether it is fated to expand into oblivion or whether it will undergo another dramatic transformation that could destroy everything we know.

The episode was rated 7.88 from 155 votes.

What is it that makes you you? Scientists are searching the brain for the core of who we are - some would call it the soul, others, our personal identity. How do we become who we are?

The episode was rated 7.91 from 128 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.

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.