Hotels have long replaced physical keys with key cards because they are safer, easy to program, and cheaper to replace if lost or stolen. Some car manufacturers have designed keyless ignition systems that let you start your car’s engine with a simple push of a button. And, many offices use cards with a chip embedded in them to give workers access to the building. But, it might not stop there. Technology just might make physical keys obsolete altogether. “For getting into your house (and your car), the technology that will kill off the physical key is your smartphone. Connecting either via Bluetooth or the Internet, your mobile device will be programmed to lock and unlock doors at home, at the office, and elsewhere,” Kiplinger.com said in an article published on its website. “The secure software can be used on any mobile device. So if your phone runs out of juice, you’ll be able to borrow someone else’s device and log in with a fingerprint or facial scan.” And, if by chance your phone is stolen, all you’d need to do is log in and change the digital keys.