i am pleased to have lisa randall back at this table. welcome. >> thank you for having me here. >> rose: so let's talk about -- we've tabled about dimensions, which i understand very little, and then dark matter which i understand evend3 less. >> right. >> rose: so what is it? first, let me say one of the pleasures of h this book is being able to connect this really theoretical work that i do to things that are more concrete and we'll get to that. >> rose: like dinosaurs? like dinosaurs and the university and the galaxy. >> rose: astounding interconnectedness of the universe. >> and that's an important part of it, but i will start by saying what dark matter is. people think it's such a complicated idea and sounds so exotic. but what does matter is it's matter. what do we mean by matter? stuff that interacts with gravity like matter. iit clumps into stuff and interacts with gravity but doesn't interact with light. we should have called it transparent matter. dark absorbs light but this stuff light passes through. billions of dark matter p

. ♪ ♪ here, a lisa randall is professor of silence at harvard. her specialty is physics.rch theoretical insights to help us better understand the interactions of matter. her books include "knocking on heaven's door." her latest is called \ -- "darktest is called matter and the dinosaurs." we talked about dimensions, which i understand very little, and i talked about dark matter, which i understand even less. what is it? i connect the theoretical work i do to things that are more concrete, like dinosaurs. and the astounding interconnectedness of the universe. lisa: that is an important part. i will start with dark matter. people think it is complicated and exotic, but dark matter is matter. what do we mean by matter? stuff that interacts with gravity. it clumps into galaxies, for example. -- why do wee call call it dark matter? because it does not interact with light. we should call it transparent matter, because this stuff has light passing through. ilion's of dark matter particles are probably passing through you every second. -- billions of dark matter particles are pro

. ♪ charlie: lisa randall is here, a professor of science at harvard. her specialty is physics.esearch connects theoretical insights to help us better understand the properties and interactions of matter. her books include "worked passages and "knocking on heaven's door." her latest is called "dark matter and the dinosaurs." welcome. lisa: thank you for having me. charlie: we talked about dimensions, which i understand very little, and i talked about dark matter, which i understand even less. what is it? lisa: one of the pleasures of this book is being able to connect the theoretical work i do two things that are more concrete. charlie: like dinosaurs? lisa: and the universe. charlie: and the astounding interconnectedness of the universe. lisa: that is an important part. i will start with dark matter. people think it is complicated and exotic, but dark matter is matter. what do we mean by matter? stuff that interacts with gravity. it clumps into galaxies, for example. it's not spread uniformly. it acts with gravity. but why do we call it dark matter? because it does not interact