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Today I'm speaking about the first of the three great partial differential equations. So this one is called Laplace's equation, named after Laplace. And you see partial derivatives. So we have-- I don't have time. This equation is in steady state. I have x and y, I'm in the xy plane. And I have second derivatives in x and then y. So I'm looking for solutions to that equation. And of course I'm given some boundary values. So time is not here. The boundary values, the boundary is in the xy plane, maybe a circle. Think about a circle in the xy plane. And on the circle, I know the solution u. So the boundary values around the circle are given. And I have to find the temperature u inside the circle. So I know the temperature on the boundary. I let it settle down and I want to know the temperature inside. And the beauty is, it solves that basic partial differential equation. So let's find some solutions. They might not match the boundary values, but ...

We're speaking today with Eric Brynjolfsson, a professor here at MIT Sloan School of Management, the director of the MIT Initiative on the Digital Economy, and co-author of a bestselling book, The Second Machine Age, a book that really has gotten the conversation going about how important today's digital economy is, how the technologies that are coming along are going to have an enormous effect on the future of work. So Eric, thank you for joining us. It's a real pleasure. Good. Let's get started. Why don't you tell us why you think the current technological wave of innovation is as important as the first Industrial Revolution, with the steam engine and all the things that went with it. Well, you know, technologies make a huge difference in the living standards of people. For centuries, living standards were essentially stagnant until James Watt and others developed a better steam engine, and that ignited the Industrial Revolution. And ever since then,...

We're speaking today with Tom Perez, the Secretary of Labor for the United States Department of Labor. So thank you, Mr. Secretary, for joining us. Oh, it's a pleasure to be with you. Maybe you could talk a little bit about what's changed since you and I entered the labor force a number of years ago. I'm thinking about a good friend of mine whose dad graduated high school, went to work at Bethlehem Steel, and worked there for 42 years. And as we fast forward to today, it is much less frequent to see someone at a job for 30, 40 years like our parents' generation. And once again, you look in the world of manufacturing just to take one example. The jobs of today are quite different than the jobs of yesterday. And frankly, in many cases, a high school degree simply won't suffice. And so my parents always taught me education is the great equalizer. It's what made America a superpower. This commitment to free public elementary and secondary education...

Today we're speaking with Liz Shuler, the secretary treasurer of AFL-CIO. Liz is not only the chief financial officer for the AFL-CIO, she has a special interest and responsibility in working with young people to introduce the Labor Movement to them and to learn from them about what they would like to see the Labor Movement of the future look like. So I'm the secretary treasurer, which is the chief financial of the AFL-CIO. We have 57 affiliated unions. And I actually came up through one of those unions, the International Brotherhood of Electrical Workers, as a rank and file member. And my responsibilities here are to manage the money and make sure that we're using the dues money wisely and building program, making sure that our finances are in order. But in addition to that finance hat, I also work to engage, educate, mobilize young people in our movement, particularly focused, as a woman officer, in making sure that we are engaging women in our Labor Movemen...

And speaking of VSEPR, that's what we did last lecture. We're going to move on today. But I want to just clarify something about VSEPR. When I was talking about this I tried to put two different concepts in the same place. And I put something in the table that shouldn't have been there. And people corrected me. I want to be sure that there is no confusion around this. So what we had was a case of formaldehyde. And we had the case of SO2. And I want to be really clear about this. Both of these molecules, when you're thinking about VSEPR, the number of electron domain count-- Right. Remember, that's how we start. The number of electron domains is the same for both of them. And we did this on Wednesday. Right. And if the number of electron domains is the same, then the electron domain geometry is trigonal planar. Right. OK. But I was also telling you about repulsion order at the same time. And so I put the wrong thing in the table. And then I erased it. A...