Luminosity is just another and advanced word for light just as AP classes are more advanced than regular. People always complain about the workload that AP classes offer. What they have to know, however, is to face the truth. Light is very revealing to our eyes and sight is one of the most trustful senses. The truth is sometimes hard to overcome so like in AP class, you have to see it to believe it and to study that material and get the 5 on the AP exam.