Edward Witten

As for the forces, electromagnetism and gravity we experience in everyday life. But the weak and strong forces are beyond our ordinary experience. So in physics, lots of the basic building blocks take 20th- or perhaps 21st-century equipment to explore.

If I take the theory as we have it now, literally, I would conclude that extra dimensions really exist. They're part of nature. We don't really know how big they are yet, but we hope to explore that in various ways.

Sometimes you see films, not just science fiction films, where you get the sense that if the camera were to pan just to the left or the right, all of a sudden you'd be seeing light stands and crew standing around. But with 'Blade Runner,' the beauty of it is that it felt like a real, breathing city.

By irreducibly complex I mean a single system composed of several well-matched, interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning.