8-20-2007: Switched tabs to PhetTabbedPane 8-20-2007: Changed tab names to “One Atom (Absorption and Emission)” and “Multiple Atoms (Lasing)” 8-20-2007: Changed actual image from PNG (300kb) to JPG (100kb) 8-20-2007: Increased the range under which absorption is possible by a factor of 5. 8-20-2007: Changed the display for a matching wavelength from "flashes 5 times" to solid bumps (not flashing) 7-5-2007: Fixed: Can move energy level up off the screen and lose it (in current version, it’s constrained to not move this far).