Live tech demos are a bitch. It was true 15 years ago when Steve Jobs famously couldn't get his brand new iPhone 4 to load a website on stage, and it was true yesterday, when Mark Zuckerberg couldn't accept a video call sent to his smart glasses. And his wasn't the only demo that wouldn't work for the same reason. We've solved a lot of new and interesting technological challenges over that time frame but we haven't fixed the physics of WiFi signal interference, sadly.1And it's too bad because it...