isn't the definition of a meter based on the speed of light IN A VACUUM? paul -----Original Message----- From: Gregory Peterson [mailto:[EMAIL PROTECTED]] Sent: Tuesday, January 23, 2001 1:51 PM To: U.S. Metric Association Subject: [USMA:10613] slowing down the speed of light This was in Monday's Globe and Mail. The tongue and cheek nature of the article aside: If this is true, could this now mean a new definition for the metre is required? greg Lights! Inaction! Monday, January 22, 2001 What's the world coming to if you can't count on light to travel at the speed of light? Two years ago, Lene Vestergaard Hau of Harvard University managed the incredible feat of slowing light from its usual speed of 299,792 kilometres a second to the speed of a bicycle. We're not sure how she did it. But then, having seen a few bicycle couriers in action, we're not even sure they travel at less than 299,792 kilometres a second. This time round, Dr. Hau and another team of scientists stopped light cold. According to Friday's article, they used a cloud of sodium gas and a laser beam to stop and restart a laser pulse, which sounds impressive even if the experiment might be hard to duplicate in the kitchen with a flashlight and a handful of flour thrown into the air. ("Stop making that mess or I'll put your lights out!") Coincidentally, the news was on the same page as an article about the massive power failure in California. In San Francisco, "downtown traffic lights suddenly went out, bringing rush-hour traffic to a halt." Cars and trucks were backed up for block upon block upon block. In other words, in an uncontrolled experiment, the absence of light was able to stop a city cold. Top that, Dr. Hau.
