I am very concerned by the fact that 9/11 could happen and many of the world's greatest engineers and scientist could be silent. I have a suggestion that we all look at who had the resources and capability to carry out the attack with such stealth and precision. Start by laying the Wikipedia page/s of one of our top "Defense Companies" and ask questions like ; Who knew enough about robotics that they could send in miniature robots ahead of time to lay trails of explosives,mask a missile like a plane (as in air traffic control simulators) and many other security sophistication and ruthlessness in business to sell it all for the right price. I won't mention names here for obvious reasons but when you read the page there should be no doubt.