Dialogue Box 4: Projecting projector costs

Inside a modern projector, you can find the latest million-mirror nanotechnology — and a light bulb. Guess which costs more

Projectors are getting cheaper and better. But they're also getting noisier and hotter — and the special magic that makes the lamps cost so much still hasn't gone away. Dialogue Box looks at what's inside, and whether it's really worth it.