'Crazy' claims or theories are often 'backed up' by what appears to be respectable scientific investigation and research - but the interesting thing is that when people attempt to replicate such investigation or research, they generally find that they can't.
True but the experiments on the WTC dust have been, and are repeatable. AFAIK all the evidence and research by ae911truth.org is genuine and repeatable/verifiable.
It's also true that the crazy claims of complete-destruction-in-a-few-seconds of a steel building by fire do not stand up to any meaningful scrutiny. There is abundant evidence of melted steel, if you can find any experiments where this has been achieved with hydrocarbon fires burning in open air, I'll admit I am wrong.
The 1500+ architects and engineers who have staked their reputations are not a bunch off loonies and nut-jobs. They are real professionals from around the world and they are joined by: Scientists for 9/11 Truth, Scholars for 9/11 Truth, Pilots for 9/11 Truth, Firefighters for 9/11 truth, Intelligence Officers for 9/11 Truth, Lawyers for 9/11 Truth, Media Professionals for 9/11 Truth, Medical Professionals for 9/11 Truth, Patriots question 9/11 (ex-military), Political Leaders for 9/11 Truth and Religious Leaders for 9/11 Truth (see www.911truth.org for links). They are joined by millions of us regular folk, who, until we tried to question the official line were not 'crazy' or 'loonies'.