Today, we're introducing a brand-new and exciting feature: Popular Science is now a totally digital publication. No more printed copies of PS - just like never before. All the content from the print issue plus an unlimited number of new articles each month, so you won't miss anything! And best of all, it's completely free. But don't worry, there will be a paywall at some point - we just wanted to make sure our new venture was ready to go when we were. We hope you enjoy your stay online and look forward to hearing your comments.