I'd love to hear opinions on Philadelphia carriers myself, so if you could possibly consider adding this, I think it would be appreciated by many.

ENGADGET: Ask Engadget: best Philadelphia wireless carrier? Mobile

"I thought it was important to outline a worst-case scenario so that those learning about nanotechnology could not consider the benefits without understanding potential risks, " Dr Drexler explained.

BBC: Nanomachine "factories" could one day sit on a desktop