There's still plenty of room to improve lighting. If you want to light an indoor room to be as bright as the outdoors on a sunny day, you're going to need a lo

There's still plenty of room to improve lighting. If you want to light an indoor room to be as bright as the outdoors on a sunny day, you're going to need a lot of heavy, expensive equipment that produces a lot of waste heat (LEDs produce way less than incandescent, but still a significant amount). It's also not going to be a full continuous spectrum of light the way that sunlight is.