BBC Radio 4's Analysis: Grey Goo's Sticky Mess, was broadcast on Thursday, 30 December, 2004 at 20:30 GMT.
Science imitating nature?
What could happen when we tinker with matter at the tiniest level - nanotechnology - has got royalty and even eminent scientists worried.
But the technology that some fear could bring so-called "grey goo" also offers us huge opportunities in energy, electronics and biomedicine.
In this week's Analysis Natasha Loder asks if the potential of nanotechnology merits running risks with the unknown and how those exploiting it should be policed.
Presenter: Natasha Loder
Producer: Simon Coates
Editor: Nicola Meyrick