Open borders could see global GDP rocket, but free movement around the world could have its downsides. We imagine a borderless world<br /><br />Click here to subscribe to The Economist on YouTube: http://econ.st/2DfRSXX <br /><br />Daily Watch: mind-stretching short films throughout the working week.<br /><br />For more from Economist Films visit: http://econ.st/2DkJBC6 <br />Check out The Economist’s full video catalogue: http://econ.st/20IehQk <br />Like The Economist on Facebook: http://econ.st/2Dg6Ddn <br />Follow The Economist on Twitter: http://econ.st/2DglS5U <br />Follow us on Instagram: http://econ.st/2Di1Dop <br />Follow us on LINE: http://econ.st/1WXkOo6 <br />Follow us on Medium: http://econ.st/2DglUL4