The bad news: just as much of the world is starting to get excited about the prospects of 3D printing, science is moving on to the world of 4D. The good news: in the future, you might not have to assemble that Ikea chair yourself. "4D printing" is the term cientists are using to refer to a technology that MIT's Skylar Tibbits talked up during a recent TED appearance. The fourth "d" here is time, referring to an object that, once printed, is capable of changing shape (over time, naturally). "Essentially the printing is nothing new," Ti
