I'v seen it burn and now know its afterproducts and how quickly and hot it burns things...how much more do you know professor Jonny?
Very patronizing, yes, but this is the kind of thing that a couple of university level chemistry courses could easily clear up without needing to be a professor in the subject.
If you've actually seen it burn, then you can probably guess a few of the limitations of the reaction.
As the iron oxide reacts with the aluminum in the thermite reaction, the rapid oxidization produces the by-products (primarily free iron and aluminum oxide) as well as a large amount of heat. Note that this is an oxidization reaction, not an explosion. Thus, the reagents react rapidly, but are in no way propelled against the force of gravity. Observing a thermite reaction clearly shows that it melts whatever it is intended to melt in the direction gravity pulls it.
Thermate, a commonly used military variant of the reaction, simply adds in some incendiary elements to increase reaction temperature and decrease ignition temperature. While this makes thermate more effect for incendiary purposes, it still doesn't make thermite "explode" and thus the reaction progresses in the same basic fashion.
The value of thermite (for purposes of clarity, I will continue to say "thermite"... "thermate" is similar enough that the distinction is unimportant) is solely in the heat released by the reaction. As you may recall from college-level chemistry, explosives work by reacting so radiply that they release energy in a shock wave that damages not only through heat but through the rapid expansion of gases. Gravity is not a major factor in explosive reactions, because the rapid expansion provides a force to act against gravity.
The thermite reaction, on the other hand, does not exhibit the rapid release of gas shown in an explosive reaction. It instead, as I mentioned above, exhibits a rapid release of heat, doing its damage through melting and burning.
Which brings us back to the subject of thermite as used for demolitions. Simply put, this is impractical to the point of being nonsense. The problem of gravity's influence over the thermite reaction makes directing the reaction to the side difficult. This is not impossible, as we were able to discover the patent for a device that directs the reaction to the side by providing the reaction with one possible outlet.
However, this device is bulky, and to use it to "weaken the columns" of the WTC would require two highly improbable/potentially impossible conditions:
1) A large number of these devices attached to the columns.
2) That the aforementioned devices were not damaged or dislodged by the plane or resulting fires.
The second condition in particular makes it pretty much impossible that, even given the device to direct a thermite reaction, any such devices were used on the columns that ultimately failed.
You can't simply stick a chunk of thermite to something and let it go.
Finally, the aluminum oxide and free iron products of the reaction are common in other instances. The presence of aluminum, iron, and steel would lead one to believe that some of these compounds would be found in the wreckage of the towers (or dust from them), especially after experiencing a catastrophic fire. Moreover, the more exotic by-products of a therm
ate reaction have
not been found; that is where the barium nitrate everyone keeps mentioning comes into play.
This is a ridiculous avenue of inquiry. You might as well argue that giant, metal-eating beavers gnawed the columns down and then disappeared.
