Miguel Alcubierre (Physicist, Nuclear Sciences Institute of the National Autonomous University of Mexico), Steve Lamoreaux (Atomic Physicist at Yale University), Steven Shu (Physicist), Chris Monroe (Quantum Physicist, University of Maryland), Steve Olmschenk (Quantum Physicist, University of Maryland), John Webb (Astrophysicist at the University of New South Wales), Joao Magueijo (Theoretical Physicist, Imperial College, London)
Freeman: Humans have always gazed up at the stars. For thousands of years, we thought they were as close as the Sun and the Moon - almost close enough to reach out and touch. But now, we know just how vast the universe is. The closest star is about 25 trillion miles away. The fastest spacecraft we have today would take more than 10,000 years to get there. To become true citizens of the cosmos, we have to do something that physics says is impossible - we have to travel faster than a beam of light.
Freeman: These strange rules for how light moves inspired Albert Einstein to rewrite the basic laws of the universe. He realized that space and time were not fixed and absolute, but connected and relative. It was an idea that led to the most famous equation in history : E = MC 2.
Carroll: Time and space are really part of one underlying thing called space-time, and how you divide up space-time into time and space depends on how you're moving. So there's various corollaries of that : once Einstein realized the time and space were the same thing, he realized that energy and mass are the same thing.
Freeman: E = MC 2 implies that the more energy you inject into a rocket, the more mass it gains; and the more massive it is, the harder it is to accelerate. Boosting it to the speed of light is impossible because, in the process, the rocket would become infinitely massive.
Carroll: The energy it takes to accelerate increases and increases as you come closer to the speed of light. If, in principle, you wanted to go the speed of light, you'd need an infinite amount of energy to accelerate you that fast.
Freeman: We've all heard of wormholes. They're cosmic shortcuts that put alien worlds practically on our doorstep. But how would we actually build one, and how would we use one? Travel by wormhole requires exotic technology - and the courage to jump into the unknown.
Shu: Quantum mechanical things are fuzzy. They're intrinsically random and unpredictable. So if we were in a quantum wormhole, we might be shaken around and we wouldn't quite know where we're gonna come out. You wouldn't wanna get into a tunnel that might end in the bottom of the Pacific Ocean or on a mountaintop that you didn't want to be on.
Freeman: Quantum wormholes have no estimated times of arrival and your destination is unknown. You could end up anywhere or anywhen. Traveling faster than light through a wormhole would be a risky ride. You've got to be willing to roll the dice.
Freeman: Cosmic strings have yet to be found and the variation in the speed of light is still just a theory. But, slowly and steadily, scientists like Joao Magueijo and John Webb are chipping away at Einstein's cosmic speed limit.
Carroll: You begin to wonder : what if it changes from place to place in the universe or maybe it was different early on in the universe's history. And if the speed of light is changing then a lot of what we think about physics could be different in the early universe to today.
Freeman: Around the world scientists are testing new technologies and probing deep into the heart of physics to uncover new laws of the universe - to find a way for us to escape our island Earth. We are still a long way from becoming citizens of the cosmos. The stars remain almost unimaginably far away. But wherever science goes next, our hopes to explore this final frontier will never be dimmed, and one day we will reach it - because whatever man can imagine, man can do.