New Scientist | Mobile Phones | Write here, write now

Soon you'll be able to post a message in the air wherever you go. Bennett Daviss explores a weird new way to keep in touch
THE KIDS are going to love this. You walk up to the teacher's desk with a little practical joke in mind. Your mobile phone suddenly bleeps, and you hear a soft whisper in your ear: "MAJOR bad mood today-don't try anything." You think better of the prank and decide to avoid certain detention. All thanks to an invisible message placed in the air above the teacher's desk.