I, like many of you, am one of the two billion people on Earth who live in cities. And there are days -- I don't know about the rest of you guys -- but there are days when I palpably feel how much I rely on other people for pretty much everything in my life. And some days, that can even be a little 1) ________. But what I'm here to talk to you about today is how that same interdependence is actually an extremely 2) ________social infrastructure that we can actually harness to help heal some of our deepest 3) ________issues, if we apply open source collaboration. A couple of years ago, I read an article by New York Times writer Michael Pollan in which he 4) ________that growing even some of our own food is one of the best things that we can do for the environment. Now at the time that I was reading this, it was the middle of the winter and I 5) ________did not have room for a lot of dirt in my New York City apartment. So I was 6) ________just willing to settle for just reading the next Wired magazine and finding out how the 7) ________were going to figure out how to solve all these problems for us in the future. But that was actually exactly the point that Michael Pollan was making in this article -- was it's precisely when we hand over the 8) ________for all these things to specialists that we cause the kind of messes that we see with the food system. So, I happen to know a little bit from my own work about how NASA has been using hydroponics to explore growing food in space. And you can actually get optimal 9) ________yield by running a kind of high-quality liquid soil over plants' root systems. Now to a vegetable plant, my apartment has got to be about as foreign as outer space. But I can offer some natural light and year-round10) ________control. Fast-forward two years later: we now have window farms, which are vertical, hydroponic platforms for food-growing 11) ________. And the way it works is that there's a pump at the bottom, which 12) ________sends some of this liquid nutrient solution up to the top, which then trickles down through plants' root systems that are suspended in clay pellets -- so there's no dirt involved. Now light and temperature vary with each window's13) ________, so a window farm requires a farmer, and she must decide what kind of crops she is going to put in her window farm, and whether she is going to feed her food 14) ________. Back at the time, a window farm was no more than a technically complex idea that was going to require a lot of testing. And then we invited people all over the world to build them and 15) ________with us. So actually now on this website, we have 18,000 people. And we have window farms all over the world.