The time had come to open the envelope, but Stephan Schlamminger, a physicist at the National Institute of Standards and Technology (NIST), wasn't sure he wanted to know the secret number that lay inside. For the past 10 years, Schlamminger had spent most of his working hours trying to measure a sin gle quantity, known as the universal gravitational constant, which determines the strength of gravity everywhere in the universe. The secret number would allow Schlamminger to unscramble his data and get his answer. ...read more read less