Bill Gates explains why we should all be optimists We sat down to talk about breakthrough technologies, China, and reasons to be cheerful with this issue’s guest editor. Gideon Lichfield There are a lot of worries today about technology’s harmful effects. How do you retain your famous optimism about it?

Look at how long people are living, the reduction of under-five mortality, the reduction in how poorly women are treated. Globally, inequity is down: poorer countries are getting richer faster than the richer countries are getting richer. The bulk of humanity lives in middle-income countries today. Fifty years ago, there were very few middle-income countries. Then there’s the ability of science to solve problems. In heart disease and cancer we’ve made a lot of progress; in some of the more chronic diseases like depression and diabetes … Even in obesity, we’re gaining some fundamental understandings of the microbiome and the signaling mechanisms involved. So, yes, I am optimistic. It does bother me that most people aren’t. See the rest of the issue Subscribe Maybe you have successful person’s bias? Of course, we have to factor that in. In my own life I’ve been extremely lucky. But even subtracting out my personal experience, I think the big picture is that it’s better to be born today than ever, and it will be better to be born 20 years from now than today. One of the technologies on your list is lab-grown meat, which is still very tentative and expensive. Why did it make the cut? Part of the reason I picked it is to remind people that clean energy does not solve climate change. Only about a quarter of emissions come from electricity generation. This is a category that people weren’t paying much attention to as a greenhouse-gas problem. And yet I think the path to solve it is clearer than in, say, cement or steel or other materials. Another of your picks is the reinvented toilet, which you call the biggest advance in sanitation in 200 years. Why? Building sewers, using clean water, having a processing plant—that’s the paradigm in rich countries. In low-income countries, the capital cost of a sewer system is just unattainable. This toilet takes the human waste, liquid and solid, and in most cases does some type of separation. The solids you can essentially burn. The liquids you can filter. That’s a huge effect on quality of life, in terms of both disgust and disease, in an increasingly urbanized world. The Gates Foundation has given out $200 million in grants to try to get this technology going. It’s not there yet. Three of your picks are about reducing greenhouse-gas emissions. You lead a $1 billion investment fund, Breakthrough Energy Ventures. But it feels like there are already a lot of technological solutions to climate change. Do we really need more? Isn’t the biggest problem political? No, the problems are when you say to India, “Provide electricity to everyone to have things we take for granted—heating, air conditioning.” Their path is to build more coal plants. That’s the cheapest form of electricity for them. In France they were asked to pay a 5% increase on their diesel price, and even that was unacceptable. The politics is where you decide how much you’re going to put into basic research or how you’re going to make things attractive for innovative companies. But if we freeze technology today, you will live in a 4 °C warmer world in the future, guaranteed. One of those picks is nuclear fusion. That’s something that’s always seemed just around the corner. What makes you optimistic about it? The company that Breakthrough put money into, Commonwealth Fusion Systems—the methods they’re using allow you to get a dramatic reduction in the size and therefore the capital cost. It’s very impressive. There are over 10 companies pursuing fusion in different ways. Most of them will not work. But these projects certainly will make a big contribution. So I think it’s important we back fusion. Sign up for The Download Your daily dose of what's up in emerging technology China is becoming a technology superpower. How do you think that will play out as fear about its power gets entrenched? The idea that they’re starting to be innovative—that is good for the world. Like most middle-­income countries, they’re more than willing to do big projects. Think of the US in the ’50s and ’60s, Japan in the ’70s and ’80s, Korea in the ’80s and ’90s. Your technological capability gets really strong, and you’re willing to go out and do very, very ambitious things. For the US, it’s good to have a sense that we have to renew our edge. In the ’70s and ’80s, when we were like, “Oh jeez, has Japan figured things out we haven’t,” we renewed our commitment to basic research. In fact, Japan was never going to overtake us in terms of scientific innovation. But I do think that was healthy for us. These are edited excerpts from a conversation with Gates at his Seattle office on January 9. You can watch a longer version of the interview here.