Why is 'x' the symbol for an unknown? In this short and funny talk, Terry Moore gives the surprising answer.<br><br>Terry Moore is the director of the Radius Foundation, a forum for exploring and gaining insight from different worldviews.<br><br><iframe src="http://www.hurriyettv.com/Embed.aspx?vid=30599&amp;w=640&amp;h=362&amp;autostart=true" allowfullscreen="" frameborder="0" height="362" scrolling="no" width="640"></iframe>