I think the person you're replying to meant having the computing be done optically (switching by some optical rather than transistor means), so in theory if you

I think the person you're replying to meant having the computing be done optically (switching by some optical rather than transistor means), so in theory if you could do that you wouldn't need any copper except to provide power to your optical computer. I doubt we'll ever get to the point where optical computing is more cost effective than what we currently have though.