In 2003, MasterCard introduced PayPass, a system in which a credit card outfitted with a near-field communication (NFC) chip could be passed within a couple inches of a reader to pay without swiping. Google Wallet, a new app for Android smartphones, takes NFC a step further, allowing users to make purchases with a wave of a smartphone. Shoppers can authorize the app to charge a preexisting Citi MasterCard card or deduct money from a prepaid debit card.
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.