Stephen: MY NEXT GUEST IS THE SENIOR LECTURER OF PURE MATHEMATICS AT THE UNIVERSITY OF SHEFFIELD. PLEASE WELCOME DR. EUGENIA CHENG! DOCTOR, THANKS SO MUCH FOR BEING HERE. [spplsudr DOCTOR, YOU'VE GOT A NEW BOOK. "HOW TO BAKE PI." AN EDIBLE EXPLORATION OF THE MATHEMATICS OF MATHEMATICS. FIRST OF ALL, WHAT IS PURE MATHEMATICS, WHAT YOU TEACH. Eugenia: PURE MATH MATHEMATICS IS THE BEST IND OF MATHEMATICS. IT'S THE MOST DELICIOUS. Stephen: THAT DOES NOT QUALIFY AS AN ARGUMENT. HOW DO YOU TEACH THE MATHEMATICS OF MATHEMATICS. AND I DON'T WANT TO GET TOO TECHNICAL HERE, WHAT THE HELL DOES THAT MEAN? Eugenia: IT MEANS TAKING VERY SIMPLE INGREDIENTS LIKE WE HAVE HERE, BUTTER AND FLOUR, DOING COMPLICATED THINGS WITH THEM AND MAKING SOMETHING DELICIOUS. Stephen: OKAY, I'M SLIGHTLY SCARED OF YOU RIGHT NOW. OKAY. THANKS VERY MUCH. THIS IS-- [picks up rolling pin] THIS IS HOW DANIEL CRAIG [earlier guest] GOT STITCHES. [laughter] OKAY, SO, TEACH ME SOMETHING ABOUT MATH WITH COOKING. Eugenia: LOOK AT THIS. Stephen: WHAT IS THAT? Eugenia: THAT IS MILLE-FEUILLE. SEE THE MATH IN THAT? ISN'T IT DELICIOUS. Stephen: IT LOOKS GOOD. Eugenia: IT MEANS 1,000 LAYERS. DO YOU SEE 1,000 LAYERS. Stephen: I SEE THREE LAYERS. Eugenia: YOU'RE NOT LOOKING CLOSELY ENOUGH. LOOK MORE CLOSELY. LOOK AT ALL THE DELICIOUS LAYERS INSIDE THE PUFF PASTRY. Stephen: YES, MA'AM. Eugenia: COULD THERE REALLY BE COULD THERE REALLY BE A 1000 LAYERS? Stephen: I DON'T KNOW. Eugenia: IT'S THE POWER OF MATH. Stephen: SHOW ME HOW. Eugenia: WE'RE GOING TO MAKE SOME PUFF PASTRY. Stephen: OKAY, GREAT. Eugenia: THE FIRST THING WE'RE GOING TO DO IS BASH THE BUTTER. Stephen: WE'RE GOING TO BASH THE BUTTER? HOW MUCH BUTTER -- HOW MUCH -- HOW MUCH BUTTER GOES INTO THAT? Eugenia: NOT VERY MUCH. VERY HEALTHY Stephen: HOW MUCH -- HOW MUCH HOW MUCH IS THIS? Eugenia: ABOUT HALF A POUND. WE'RE BASHING IT TO MAKE IT THE RIGHT CONSISTENCY TO GO IN THE PASTRY. IT'S VERY IMPORTANT IN MATH TO HAVE THE RIGHT CONSISTENCY. Stephen: MY NEXT GUEST IS THE SENIOR LECTURER OF PURE MATHEMATICS AT THE UNIVERSITY OF SHEFFIELD. PLEASE WELCOME DR. EUGENIA CHENG! DOCTOR, THANKS SO MUCH FOR BEING HERE. ( APPLAUSE ) DOCTOR, YOU GOT A NEW BOOK. "HOW TO BAKE PI." AN EDIBLE EXPLORATION OF THE MATHEMATICS OF MATHEMATICS. FIRST OF ALL, WHAT IS PURE MATHEMATICS, WHAT YOU TEACH. Eugenia: PURE MATH MATHEMATICS IS THE BEST IND OF MATHEMATICS. IT'S THE MOST DELICIOUS. Stephen: THAT DOES NOT QUALIFY AS AN ARGUMENT. HOW DO YOU TEACH THE MATHEMATICS OF MATHEMATICS. AND I DON'T WANT TO GET TOO TECHNICAL HERE, WHAT THE HELL DOES THAT MEAN? Eugenia: IT MEANS TAKING VERY SIMPLE INGREDIENTS LIKE WE HAVE HERE; BUTTER AND FLOUR, DOING COMPLICATED THINGS WITH THEM AND MAKING SOMETHING DELICIOUS. Stephen: OKAY, I'M SLIGHTLY SCARED OF YOU RIGHT NOW. OKAY. THIS IS-- [picks up rolling pin] THIS IS HOW DANIEL CRAIG [earlier guest] GOT STITCHES. (laughter] OKAY, SO, TEACH ME SOMETHING ABOUT MATH WITH COOKING. Eugenia: LOOK AT THIS. Stephen: WHAT IS THAT? Eugenia: THAT IS MILLE-FEUILLE. SEE THE MATH IN THAT? ISN'T IT DELICIOUS. Stephen: IT LOOKS GOOD. Eugenia: IT MEANS 1,000 LAYERS. DO YOU SEE 1,000 LAYERS? Stephen: I SEE THREE LAYERS. Eugenia: YOU'RE NOT LOOKING CLOSELY ENOUGH. LOOK MORE CLOSELY. LOOK AT ALL THE DELICIOUS LAYERS INSIDE THE PUFF PASTRY. Stephen: YES, MA'AM. Eugenia: COULD THERE REALLY BE COULD THERE REALLY BE A 1000 LAYERS? Stephen: I DON'T KNOW. Eugenia: IT'S THE POWER OF MATH. Stephen: SHOW ME HOW. Eugenia: WE'RE GOING TO MAKE SOME PUFF PASTRY. Stephen: OKAY, GREAT. Eugenia: THE FIRST THING WE'RE GOING TO DO IS BASH THE BUTTER. Stephen: WE'RE GOING TO BASH THE BUTTER? HOW MUCH BUTTER-- HOW MUCH -- HOW MUCH BUTTER GOES INTO THAT? Eugenia: NOT VERY MUCH. VERY HEALTHY Stephen: HOW MUCH-- HOW MUCH HOW MUCH IS THIS? Eugenia: ABOUT HALF A POUND. WE'RE BASHING IT TO MAKE IT THE RIGHT CONSISTENCY TO GO IN THE PASTRY. IT'S VERY IMPORTANT IN MATH TO HAVE THE RIGHT CONSISTENCY. THEY DON'T TELL YOU THAT IN SCHOOL. Stephen: NO, THEY DON'T. I'M GLAD YOU TEACH MATH AND NOT HEALTH. Eugenia: I'M VERY HEALTHY. WHAT ARE YOU TALKING ABOUT. Stephen: THERE'S STILL SOME WAX IN THAT. Eugenia: DELICIOUS. VERY HEALTHY WAX. WE'RE GOING TO PUT THE BUTTER ON THIS LOVELY PASTRY. Eugenia: AND WE'RE GOING TO WRAP IT UP Stephen: WHILE COUNTING OUR CHOLESTEROL. Eugenia: EXACTLY. EXACTLY Stephen: DO I BASH IT AGAIN. Eugenia: IF YOU LIKE. YOU CAN DO ANYTHING YOU LIKE. Stephen: TELL ME THE RIGHT THING TO DO. Eugenia: IT'S ANYTHING YOU LIKE. MATH IS ABOUT MAKE YOUR OWN RULES UP. Stephen: BUT BAKING IS NOT. [laughter, applause] YOU MIGHT BE A GREAT MATHEMATICIAN BUT THAT'S NOT GOOD BAKING. Eugenia: WE'RE GOING TO ROLL IT OUT. Stephen: YOU ROLL IT OUT, Eugenia: OKAY. AND WE CURRENTLY HAVE TWO LAYERS, TWO LAYERS OF PASTRY. NOW WE'RE GOING TO FOLD IT UP. Stephen: ALL RIGHT. Eugenia: I'M GOING TO FOLD IT INTO THREE. THREE. Stephen: NOW WE HAVE SIX LAYERS. Eugenia: WELL DONE! Stephen: THANK YOU VERY MUCH. WELL, THAT'S ALL WE HAVE TIME FOR. Eugenia: THANK YOU SO MUCH-- WE'RE GOING TO ROLL IT OUT AGAIN. Stephen: OKAY, Eugenia: ALL RIGHT. AND THEN WE'RE GOING TO FOLD IT IN THREE AGAIN. Stephen: OKAY. Eugenia: AND THEN IT'S GOING TO HAVE THREE TIMES SIX WHICH IS. Stephen: THREE TIMES SIX IS 18. Eugenia: AMAZING! YOU SEE? AND THEN WE'RE GOING TO DO IT AGAIN. AND IN FACT, THOUGH, HERE WHAT WE HAVE-- GO ON. Eugenia: HERE'S ONE I MADE EARLIER. Stephen: SO HERE WE'RE GOING TO-- WHAT WE'RE GOING TO DO. Eugenia: WE'RE GOING TO DO IT SIX TIMES. WE'RE GOING TO HAVE TWO TIMES THREE, THREE, THREE, THREE, THREE, THREE AND THEN WE'RE GOING TO PUT THREE LAYERS INTO THAT. Stephen: OKAY. Eugenia: SO THAT'S ANOTHER THREE. Stephen: SO IT'S THERE TO THE SEVENTH TIMES TWO. Eugenia: YOU CAN DO THAT Stephen: 4,372? Eugenia: SEE, I CAN'T DO THIS BECAUSE I'M A MATHEMATICIAN, NOT A CALCULATOR. [laughter, applause] Stephen: ALL RIGHT, HOW MANY LAYERS DO WE HAVE? Eugenia: 4 THOUSAND -- I LOOKED IT UP EARLIER ON MY PHONE. Stephen: SO DID I. Eugenia: BECAUSE MATH IS NOT ACTUALLY JUST ABOUT NUMBER S. Stephen: NO? Eugenia: THE PRINCIPLE OF THIS IS WE USED SOME REALLY TIDY NUMBERS TWO, THREE, VERY SMALL NUMBERS. Stephen: THERE'S A SMALLER ONE. Eugenia: YEAH, OKAY. AND IT QUICKLY BECAME A HUGE NUMBER! WE MADE SOMETHING DELICIOUS BY THE POWER OF EXPONENTIALS. Stephen: THE BOOK IS "HOW TO BAKE PI." DR. EUGENIA CHENG, EVERYBODY. Eugenia: THANK YOU SO MUCH. [For admin and other information see: http://www.mta.ca/~cat-dist/ ]