Randall believes in effective theories.

Lisa Randall: Do I believe in absolute truth? I believe in effective theories, so let me tell you what an effective theory is. An effective theory says basically that I can . . . If I can’t measure something, I don’t have to worry about it in the sense that, for example . . . Let’s take Newton’s laws. Newton’s laws work just fine. But we know that eventually we have to take into account relativity, if things were going really fast where we have to take into account quantum mechanics when we’re looking at really tiny scales. But for the scales we observe, you don’t have to worry about the fact that a ball is made up of atoms. It’s perfectly fine to think of it as a ball with some mass because you would never be able to measure the effects of the atoms on the ball when you’re just throwing the ball. So I guess I believe that we . . . There’s a truth that we know because it applies to the world as we’ve seen it, as we’ve measured it. That’s not to say that there can’t be other underlying truths you could see if you could understand . . . if you could really see things better; if you could test them better; if you could measure them better. So I think anything we know could be upset if you look at regimes outside the regime of which we studied them. So . . . But that’s not to say the truth isn’t absolute. It’s absolute in the scales that we’ve seen it; but it’s just not absolute in the sense of applying the most fundamental skills. Recorded On: 11/2/07

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