lisa randal is here, a professor of physics at the harvard university. he's has done ground breaking work on the impact of extra dimentions. her current focus is on the implications of experiments taking place at the large head ron collider. she writes about this and more in knocking on heaven's door. how physics and scientific thinking illuminate the universe and the modern world. mi pleased to have lisa randall back at this table. welcome. why do physics appeal to you? >> that is an interesting question. i always liked math. i liked path because it seemed to be predicting and have answers. but the idea of just doing abstract math wasn't as interesting. the idea that you can explain to the university that you can actually test some of the ideas that you have, of course mathematical they areup can be true whether or not it's realized in the world. but the idea of using formulas, using math to actually explain and predict and be rational about what is going on in the universe and the fact that youcan explain and predict things, it's a wonderful thing. and

we conclude with lisa randal, professor-of-physics at harvard her book is called knocking on heaven's illuminate the universal and the de