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?

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?

Since the ancient Greeks first speculated that everything they observed in reality was the result of the interaction of tiny particles they called atoms, great thinkers have tried to find a single mathematical formula that governs and explains the workings of the entire universe. So far, though, even minds as brilliant as physicists Albert Einstein and Stephen Hawking have been unable to come up with that single grand equation of everything, also known as the theory of everything, or the final theory. Nevertheless, they continue to try, because without that final piece of the puzzle that is reality, the sum total of what we know falls a bit short of making sense.

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.

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.

We move and live in three dimensions: length, width, and height. However, Einstein revealed what was once unimaginable: time is actually a dimension and linked with space itself. To reconcile the massive cosmic and miniscule quantum worlds, physicists are realizing four dimensions may not be enough. They're unraveling up to eleven dimensions. How could this be true? Where could these dimensions be?

In the premiere episode of the second season, Morgan Freeman dives deep into this provocative question that has mystified humans since the beginning of time. Modern physics and neuroscience are venturing into this once hallowed ground, and radically changing our ideas of life after death. Freeman serves as host to this polarized debate, where scientists and spiritualist attempt to define 'what is consciousness,' while cutting edge quantum mechanics could provide the answer to what happens when we die.

Can we perceive objects and events beyond the world detected by our five senses? The true limits of our human brain remain a scientific mystery. New studies in neuroscience are showing that our minds can really detect events and objects that our conscious selves know nothing about. Can we predict events in the future? Is there such a thing as a global consciousness? Could physical laws on the cusp of being discovered be at the root of all this?

Science fiction writers have always had their little green men. But these humanoid aliens were based soundly on Earth-based life, not any extra terrestrial evidence. Today, we've discovered hundreds of planets around other stars. As we learn what some of these alternative Earths might look like, science and imagination have allowed us to use real science to imagine the biology of their inhabitants. Will they have two eyes? Two legs? What color will their skin be? Which species on Earth can give us clues about likely biology of aliens? And what can we learn from how life on Earth developed to help us understand what ET really looks like?

Most scientists believe that you are not really you, but rather, you all. On the edge of space, buried in a black hole, or right on top of you, there could be an exact copy of yourself living a parallel reality. In those parallel worlds, you may be living your wildest dreams, or your worst nightmares. Finding them is no longer restricted to the realm of science fiction. Recent game-changing theories now suggest that if these worlds exist, intelligent life in these alternative worlds could be trying to send us messages. As scientists further unravel this astounding possibility, a new possibility emerges: the fate of our entire universe may depend on these hidden cosmic twins.