Almost every high-profile smart phone to be unveiled at CES this week boasts a super-fast "4G" network connection. But depending on the carrier, "4G" can mean many different things. Here's the breakdown.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.