Answer by Roman Manziyenko, AU School of International Service Scholar
The fundamental issue here is display technology like iPads, computers, smartphones and TVs all generally use backlighting technology, which directs light through a filter (LCD screen or otherwise) and straight into your eyes. Human eyes aren't great at staring directly at light sources (think about how often you look at the sun, a fire, or a lightbulb). That's why it hurts to do so for extended periods of time.
E-books overcome this in the same way that paper books and cave paintings do. They simply provide the filter (colors and shades) and allow another light source to bounce off of it and to your eyes indirectly. The new Kindle Paperwhite (or Nook with GlowLight) takes that concept to the next level. The device has a light source reflected from just above the surface of the filter, such that light still bounces down before hitting the filters and being reflected to your eyes. One of the reasons it took Amazon (and Barnes and Noble) so long to develop this technology is because they didn't want to have an omnidirectional light source above the filter, which would shine directly at the reader's eyes.
Reading on the Paperwhite is like reading from a book in a well illuminated room. Except the only thing illuminated is the text.More questions on Kindle: