The towers and WTC 7 collapsed because of yawning? I haven't heard that theory before.
Can you answer the question? If it wasn't the airplanes or debris from the towers (in WTC 7's case), then what was it? This is basically a one word answer.
Also, can you answer my challenge from the other thread? I am asking incredibly easy questions about a theory that you (all Truthers) are believing in and that shapes your entire political outlook and you (all Truthers) don't answer them.