The central point to this latest video is this: as weve shown in previous chapters of the Crash Course, our global economy depends on continual growth to function. And not just any kind of growth; but exponential growth.But in order to grow, it must receive an ever-increasing input supply of affordable energy and resources from the natural world. What Im about to show you is a preponderance of data that indicates those inputs will just not be there in the volumes needed to supply the growth that the world economy is counting on.In short, on top of all the debt and other economic messes weve made for ourselves, constraints from the natural world will increasingly place limits on economic growth in a way we havent had to deal with over the past century. This is why Im so confident in the claim that the next 20 years will be completely unlike the past 20.So understanding the dynamics at play here is key to forecasting what the future will be like. Since energy is the master resource, thats where were going to start.