Does Light Always Travel at Light Speed?

light-always-travel-light-speed Credit: Photo by Mike Grauer Jr/Moment/Getty Images

Light typically travels at 186,000 miles per second, but scientists have found a way to slow it down to 38 miles per hour. A team at the Rowland Institute for Science has found a new state of matter to help slow light down. Sodium atoms were cooled almost to absolute zero, which is 459.67 degrees Fahrenheit below zero. That’s lowest temperature theoretically possible. They then shot a laser through the extremely cold sodium atoms, which acted like “optical molasses” to slow down the beam of light.

When light passes through something like water or glass it slows down very slightly as the light’s photons interact with the molecules in the substance surrounding it. The process used by the scientists at the Rowland Institute for Science is just a very, very amplified version of that interaction.

Lead scientist on the project Lene Vesergaard Hau says this could lead to many practical uses in the future. She envisions the ability to send data and pictures in less space and with less power, and developments in laser projection systems and night vision cameras.