# #Mon Aug 09 11:42:17 CEST 2010 Slide__Ww2M8KOaEd-WfYQ0GneCwQ_subTitle= Slide__Ww2M8KOaEd-WfYQ0GneCwQ_title=Why does a mass act like a lens ? Slide__Ww2M8KOaEd-WfYQ0GneCwQ_footer=