The details of what makes AR challenging from a technical standpoint are complex. But they can be boiled down to three simple words; size, power, and heat. We've come a long way when it comes to miniaturized processors and graphics cards, but we're still not quite at the level we need to be to make high-end everyday AR a, well, reality. Processors get heavy quickly when worn on your face. Some AR prototypers think that the answer is an external computing pack about the size of an external hard drive. These packs would do all the actual heavy lifting for the AR processes and allow for lighter and more ergonomic frames. Rendering an AR experience takes a lot of power. Think about how much your cell phone battery drains when you're streaming video. Now imagine if it wasn't merely streaming images but generating those images and doing so while also tracking every other object in a room and recalibrating the image every time your head so much as twitches. Again, something the solution is to have an external battery pack that clips to your belt. That might work for now, but ultimately, the power problem is one we're going to have to overcome within the frame of the device if we want AR to reach its full potential. You've probably noticed that every PC or laptop you've ever owned as a fan inside. Computing generates heat, a lot of it. In fact, the more power used, the more heat that gets generated, and the smaller the device, the slower it gets rid of that heat. AR is a highly complex process, and therefore generates a lot of heat. That heat in turn can slow down processors or even short them out altogether. Managing this heat is even harder with the limited size and structural requirements of an AR headset. There isn't much room for heat sinks and fans in a device that's supposed to eventually weigh a few ounces and look like an ordinary pair of glasses. Some AR headset manufacturers are packing all of the processing power into the frames of the visor itself. Meanwhile, other manufacturers are using external hardware like battery packs to address the issue. Each comes with its sets of pros and cons. There two takes on how to strike the balance between the issues of size, heat, and power.