> A screen has to put out enough photons that a pupil two millimeters wide can capture enough light from it half a meter away. That fundamental principle isn't

> A screen has to put out enough photons that a pupil two millimeters wide can capture enough light from it half a meter away. That fundamental principle isn't going to change anytime soon, and since that's the largest piece of energy consumption in phones these days, power requirements aren't going to drop significantly in the foreseeable future The technology isn't there yet, but I would love to see the day when we can make laptop screens (and the like) out of e-ink-like displays. I don't like staring at backlit screens all day. A computer screen has about the same luminous intensity as a 40W bulb[0], which is not a pleasant thing to stare at all day. If only we could figure out a way to make e-ink remotely usable with high refresh rates, etc[1]., we could rely on external lighting (which is usually available) and get dramatically better battery life out of our laptops and/or phones. It could even fall back on "frontlighting" (what the Kindle Paperwhite does) for nighttime usage. [0] Preempting any physicists' objections: yes, I know that watts do not measure luminous intensity (that would be the candela), but a 40W bulb is a familiar reference point, and this comparison is roughly in the right ballpark. [1] Which is a big hurdle, and why I admit that the technology isn't there yet.