photo courtesy Dave Brosha Photography ...Photography means 'writing with light'.  English astronomer John Herschel, whose father discovered infrared, coined the term... 

...light moves along at the speed of light (186,282.4 miles per second) only in a vacuum.  In a diamond, it only moves at 77,500 miles per second...

...light has no mass but it does have momentum...

(info from Discover Magazine March 2010 - discovermagazine.com)

Although Katrina, the young genius heroine of my Back Tracker novels primarily works her magic with computers, she is fascinated by physics, especially Quantum Physics.  Read an excerpt at:http://www.eileenschuh.com/back-tracker-series/