I am a retired Professional Engineer BME 1961 U of MN. I was licensed in both MN and WI. I have participated in the design and building of 4 reinforced concrete buildings. I have personally witnessed the implosion of two tall buildings. My first impression of the the Twin Towers collapses were that they were implosions, but I couldn't explain all the dust that accompanied those possible implosions.

A couple of months ago a friend of mine told me had had just seen the architect of the Twin Towers say that the eplosives were placed when the buildings were built. He ordered the VCR tape of that program, The tape he got was the show he saw. There was an interview with the architect but he made no mention of the explosives.

Recently, I was sent an email that stated that the Twin Towers and WTC 7 were constructed like missile silos and submarine bases. The rebar reinforcing rod had a thick coating of C4 plastic explosive attaced to a detonator. All it takes is a coded phone call to implode the missile silos, submarine pens, and supposedly the Twin Towers. I thing that this is highly likely because it is only way to explain the tremendous amounnt of dust.

A firefighter who spent 10 days helping to clean up the WTC site says he never found anything larger than part of a telephone touch tone pad from a giant building full of office equipment and furniture. He says that no one else he knows that helped in the cleanup found anything any larger that than.

The tall building I witnessed being imploded did not create much dust when they fell. That is why I had questions about possible implosions all along. This C4 theory would create a terrific amount of dust because everything including the concrete was vaporized.

A janitor has testified that he was down in one of the subbasements of the North Tower. He felt an explosion down below him just seconds before the plane hit the upper part of the North Tower. He has 14 corroborating witnesses including a person who was horribly burned in the expolosion that happened below him. None of these witnesses were asked to testify in any investigation.

The Twin Towers were the dream of David and Nelson Rockefeller. The land the WTC buildings were built on was donated to the NY Port Authority by the Rockefeller Brothers. The original John D. Rockefeller was known to have blown up obsolete plants and buildings and blame it on his competition whose stock immediately took a nosedive. Old JD Rockefeller bought their stock for ten cents on the dollar.

Time to defoliate the Shrub.

Your sarcasm is sometimes very hard to detect. Very hard.

Here I am back again -- just another "anti-American", another "liberal" -- because I forgot something...

That orange jumpsuit Nicholas Berg was wearing in the infamous beheading video -- what's up with that? Do the terrorists and the US military both order their prisoner garb from the same catalog? And have and follow the same procedure for putting prisoners in regulation garb? Was Berg wearing it when he was captured? Did he have the jumpsuit in his suitcase? Did the terrorists just happen to find one on the street, or steal one from the Americans?

Personally, I have no firsthand knowledge about what happened to Nicholas Berg. So I'm not saying it was a 'psy-op' or something like that, although it's pretty clear the timing was convenient in that it took some of the attention away from the Abu Ghraib scandal, but simple coincidence also explains that.

But I have not seen one credible explanation of the orange jumpsuit. Not one. You can be the first!

Why is it "anti-American", or "liberal", to point out, and going further to ask questions about, things that appear odd or are left unexplained, including by official government investigations whose job it is to explain things, regarding 9/11? Maybe you can explain that.

And once you get on a roll, explaining-wise, take a shot at these:

Who were the 9/11 hijackers? As has been well documented, many on the list originally circulated by the FBI later turned up alive -- there is plenty of info available about that. Was this ever corrected? Do we know even today, almost four years later, who they really were? If not (and why not?), and I'm just being logical here, how can we be absolutely, 100% sure what their motivation was, and who was behind them?

Next, search the internet and find fotos and video of building seven after the attack, including its collapse -- there are a few sites on-line where you can find these things. What you'll see is this: apparently only minor-looking exterior damage caused by debris hits from the falling twin towers. A few small fires can be seen -- nothing major. And then the collapse, which is almost perfectly symmetrical, and looks exactly like a controlled implosion. Again, you don't have to take my word for it -- watch a video of it yourself. Then answer: How can that be? And why wasn't the investigation able to intelligently and scientifically answer this question either? After all, analysis commonly undertaken after such catastrophes should be able to do that, e.g. to perhaps help design safer buildings in the future. Note: I'm not saying I know the answer. But I do find the whole situation to be a little bit curious.

In contrast, check out the skyscraper fire in Madrid earlier this year. It was spectacular -- the building burned like a torch for hours. And yet did not collapse. It was also a steel-framed building, older than WTC 7.

Again: I do not claim to know what happened. But I find the comparison interesting.

About the "anti-American" and "liberal" stuff: Grow up, man.

Correction: Ok, now that I re-read what I just wrote, I would note that an architectural arch is not actually using tension (well, in a way you could say it is, but it does not really count).

Hmm...I am rather jaded about Bush too, but this is not a prudent tree to be barking up. Like you, I am not a structural engineer, but I am an engineer. And I know that a lot of engineering professors have been looking at the situation independently, and even using it as class projects, etc. The fact that this has been going on across 100's of American universities and an economist (which is not even a true science, much less engineering) is making this claim says all that needs to be said in my opinion.

The fundamental engineering problem, however, where you have a sudden release or input of energy in a very short period of time (essentially an impulse) and the system has to dissipate it is a very general one. It does not matter if you are talking about a structural, mechanical, or electrical system, fundamentally it's all the same.

I do know enough about statics to know that a structure like a skyscraper employs both tension and compressive force in the structural members. An archer's bow is an excellent example of these two types of forces working together (as is the classical architect's arch). As such, these ridged structures store huge (yes, very huge) amounts of potential energy; when some of these members become weak (as might be the case from heat) they not only releases a huge amount of energy, but can set off a chain reaction as other members release their potential energy as well. (Imagine cutting the string of a taunt bow.) I would point out, in case it is not obvious, that the amount of energy required to start this series of events can be trivial compared to the amount of energy released (just as in the case of cutting the string on a bow).

Ideally, everything would fail gracefully, but in the case of these tall structures, they were simply too ridged to be able to dissipate that amount of released energy in that short period of time. So naturally, the energy was released at the weakest members, which in turn released their potential energy, and so on and so forth.

Granted, this is not a very detailed analysis of the situation, but the idea that only demolition experts could provide enough energy to knock them over, or to pancake, etc, is pure rubbish.