One way that sensors can track your position without using an array of satellites is by measuring your acceleration as you move around -- but unless you're piloting a jumbo jet, current devices aren't very accurate. Researchers at Caltech hope to change all that with a new, ultra-sensitive accelerometer they developed, which uses laser light to detect motion changes. The scientists managed to shrink a so-called large-scale interferometer down to micro-scale sizes, creating a device "thousands of times faste
