We know WHAT happened on 9/11 - the buildings mostly turned to dust before they reached the ground.
drjudywood.com
We don't know who were the perpetrators. However, "Dr Judy Wood has discovered that ARA and SAIC are manufacturers of Directed Energy Weapons and have expertise in Psychological Operations (PSYOPS)."
http://drjudywood.com/articles/ARA/ARA.html
http://www.checktheevidence.co.uk/cms/index.php?Itemid=60&id=151&option=com_content&task=view