When you look at the huge volume of “stuff” written and filmed about 911, one can’t help but be inundated by all sorts of “conspiracy theories” and various sorts of fantastical ideation.
As I’ve worked a long time in a computer security context, I’ve become very aware that there ARE a lot of folks “out to get you” and there are a lot of organized efforts (think China, Russia, NSA, CIA, GCHQ, Soros etc. etc.) so for me, there quite clearly ARE conspiracies (it is one of the most prosecuted crimes in the USA as a group “Conspiracy to” FOO). Then the notion of something being theoretical, well, frankly most of what science “knows” is theories. So, for me, a “conspiracy theory” is NOT a pejorative. It is used as a pejorative by those who desire to denigrate others.
That said, there’s a lot of “crap” that passes for reasoning about why things happen and who is behind them. In general, most things that have an element of the “fantastic” about them are pure crap and imagination. But some small bit are not. Think of all the UFO sightings that, in retrospect, were likely the early testing phases of the Stealth Program from the USAF. Stealth is, itself, a bit fantastical. But there’s a clue here. One ought to look for the LEAST fantastical explanation for things outside the expected and not go running off to the most fantastical as the first stop.
Another clue is to NOT go beyond the “facts clearly in evidence”. We had mysterious flying things that were hard to see and strangely shaped and didn’t show up on radar. Those facts nicely fit “somebody made a really weird aircraft and the government spends $Billions on aircraft so likely the Government made something new and weird”. One need not add to that any element of “Life from other planets came here and are doing nefarious things to us!”. There is NO data nor evidence of anything “alien” or “nefarious” (beyond normal government secrecy) or from anywhere off planet in the sightings.
Those two rules taken together will let you avoid a LOT of crap theories. “What are the facts in evidence and do they support the claim?” Or alternatively: “Does this claim rest on assumptions not in evidence in the known facts?”. Then “Is there a less fantastic mechanism for the same result?”.
So, for example, a lot of noise is made about specks of light moving in exotic ways outside the windows of space craft. Two points can explain all of them without the need to invoke space aliens. 1) Lots of crap gets dumped from space craft or gets chipped off, including some that vent water / ice bits. 2) Optical effects make it very hard to tell if that speck of light is an out of focus dust mote 1 inch outside the window or a 747 sized craft miles away, or even just a reflection from all the optical surfaces; especially for cameras.
I’ve run to the rooftop with a dozen friends to “see the UFOs”. It was a magnificent experience, the three of them in formation flying along… Until I pointed out that it was actually a stable cloud formation moving the other direction making it look like 3 early stars were moving, then the illusion was lost. (Sorry I rained on everyone’s parade, actually. It WAS a special feeling… for a minute…) I’ve seen a vehicle floating in the sky speeding the other way from my car… and then another… and another… and then figured out it was some distant lights on the ground being reflected oddly in the car windows in the middle of nowhere. Then there are the dozens of photos with odd artifacts. From the iris vs sun causing all sorts of lens flairs and interesting visuals (often used to artful effect by many – if you see a lightly colored series of hexagons or octagons with a bright light source just toward the edge of the image or off frame, that’s the image of the iris in too much strong lighting and lens refractions / reflections)
It is infinitely more likely that any “odd thing” you see in photographs, or even in person, is some kind of optical effect and nothing to do with space aliens or ships in the sky. ( I won’t even get into the odder real physical things like “sun dogs” and even the simple rainbow).
So in general, most of the stuff I’ve seen about 911 has quickly dissolved into a ‘crap theory’ on close inspection and application of a little bit of looking for “unusual mundane” instead of fantastical explanations.
Take, for example, the “must have used explosives to bring it down” and the “fire not hot enough to melt steel” ideas. First off, realize buildings are made to just barely stay up, then you add more to the design to give it a safety margin. Depending on who and where, that can be 50% or a double or other values. But we are not talking 10 times. Now look at the World Trade Center (WTC) towers. The typical skyscraper folks think of is a box of beams and posts with sheathing on the outside. LOTS of steel through the whole volume. The WTC Towers were not like that. They are a hollow tube with expansive open space floor plans without posts scattered through them.
On September 20, 1962, the Port Authority announced the selection of Minoru Yamasaki as lead architect and Emery Roth & Sons as associate architects. Yamasaki devised the plan to incorporate twin towers; Yamasaki’s original plan called for the towers to be 80 stories tall, but to meet the Port Authority’s requirement for 10,000,000 square feet (930,000 m2) of office space, the buildings would each have to be 110 stories tall.
Yamasaki’s design for the World Trade Center, unveiled to the public on January 18, 1964, called for a square plan approximately 208 feet (63 m) in dimension on each side. The buildings were designed with narrow office windows 18 inches (46 cm) wide, which reflected Yamasaki’s fear of heights as well as his desire to make building occupants feel secure. Yamasaki’s design included building facades sheathed in aluminum-alloy. The World Trade Center was one of the most-striking American implementations of the architectural ethic of Le Corbusier, and it was the seminal expression of Yamasaki’s gothic modernist tendencies
Note that the size was increased, so some redesign was done. I doubt this matters, but often a design is made to what the designer things is the best stopping point, then when pushed, pushes the design a bit beyond the most trusted range. Did that happen here? I have no idea.
Also note the sheer size of it. 110 stories. That’s a LOT of potential energy, turning to kinetic in the fall. More than enough to start fires and / or grind concrete.
Aluminum sided. Aluminum is both soft (so easily bent and ground up) and flammable. Though a bit hard to get started burning, it does burn, especially when ground finely or when mixed with iron oxides or other materials.
These points will matter when we get to the video down below.
In structural engineering, the tube is a system where, to resist lateral loads (wind, seismic, impact), a building is designed to act like a hollow cylinder, cantilevered perpendicular to the ground. This system was introduced by Fazlur Rahman Khan while at the architectural firm Skidmore, Owings & Merrill (SOM), in their Chicago office. The first example of the tube’s use is the 43-story Khan-designed DeWitt-Chestnut Apartment Building, since renamed Plaza on DeWitt, in Chicago, Illinois, finished in 1966.
The system can be built using steel, concrete, or composite construction (the discrete use of both steel and concrete). It can be used for office, apartment, and mixed-use buildings. Most buildings of over 40 stories built since the 1960s are of this structural type.
The tube system concept is based on the idea that a building can be designed to resist lateral loads by designing it as a hollow cantilever perpendicular to the ground. In the simplest incarnation of the tube, the perimeter of the exterior consists of closely spaced columns that are tied together with deep spandrel beams through moment connections. This assembly of columns and beams forms a rigid frame that amounts to a dense and strong structural wall along the exterior of the building.
This exterior framing is designed sufficiently strong to resist all lateral loads on the building, thereby allowing the interior of the building to be simply framed for gravity loads. Interior columns are comparatively few and located at the core. The distance between the exterior and the core frames is spanned with beams or trusses and can be column-free. This maximizes the effectiveness of the perimeter tube by transferring some of the gravity loads within the structure to it, and increases its ability to resist overturning via lateral loads.
This matters because the WTC Towers were built that way:
The structural engineering firm Worthington, Skilling, Helle & Jackson worked to implement Yamasaki’s design, developing the tube-frame structural system used in the twin towers.
The tube-frame design, earlier introduced by Fazlur Khan, was a new approach that allowed more open floor plans than the traditional design that distributed columns throughout the interior to support building loads. The World Trade Center towers used high-strength, load-bearing perimeter steel columns called Vierendeel trusses that were spaced closely together to form a strong, rigid wall structure, supporting virtually all lateral loads such as wind loads, and sharing the gravity load with the core columns. The perimeter structure containing 59 columns per side was constructed with extensive use of prefabricated modular pieces, each consisting of three columns, three stories tall, connected by spandrel plates. The spandrel plates were welded to the columns to create the modular pieces off-site at the fabrication shop. Adjacent modules were bolted together with the splices occurring at mid-span of the columns and spandrels. The spandrel plates were located at each floor, transmitting shear stress between columns, allowing them to work together in resisting lateral loads. The joints between modules were staggered vertically, so that the column splices between adjacent modules were not at the same floor.
Now first off, notice that the interplay between the spandrel plates (think arch supports at the tops) and the columns is very important to this structure having strength and rigidity.
Next notice that it uses “high strength steel”. This is not your run of the mill iron beam. Typically they are made of special alloys and get some of their strength from the final heat treatments. Heat some of those steels, they become more ordinary steels and lose a lot of strength even when cooled again. IMHO, this matters.
The exterior tube provides a lot to most of the strength. Without either their special steel strength or the stabilization of the floor plates they can not support the load of all the building above them.
The core of the towers housed the elevator and utility shafts, restrooms, three stairwells, and other support spaces. The core of each tower was a rectangular area 87 by 135 feet (27 by 41 m) and contained 47 steel columns running from the bedrock to the top of the tower. The large, column-free space between the perimeter and core was bridged by prefabricated floor trusses. The floors supported their own weight as well as live loads, providing lateral stability to the exterior walls and distributing wind loads among the exterior walls. The floors consisted of 4 inches (10 cm) thick lightweight concrete slabs laid on a fluted steel deck. A grid of lightweight bridging trusses and main trusses supported the floors. The trusses connected to the perimeter at alternate columns and were on 6 foot 8 inch (2.03 m) centers. The top chords of the trusses were bolted to seats welded to the spandrels on the exterior side and a channel welded to the core columns on the interior side. The floors were connected to the perimeter spandrel plates with viscoelastic dampers that helped reduce the amount of sway felt by building occupants.
“Viscoelastic dampers” come in many kinds, but “rubber block” is a good image… So what happens to all that necessary bracing as the “viscoelastic damper” gets heated and burned away?
The tube frame design, using steel core and perimeter columns protected with sprayed-on fire resistant material, created a relatively lightweight structure that would sway more in response to the wind compared to traditional structures, such as the Empire State Building that have thick, heavy masonry for fireproofing of steel structural elements.(p138) During the design process, wind tunnel tests were done to establish design wind pressures that the World Trade Center towers could be subjected to and structural response to those forces. Experiments also were done to evaluate how much sway occupants could comfortably tolerate; however, many subjects experienced dizziness and other ill effects.(p139–144) One of the chief engineers Leslie Robertson worked with Canadian engineer Alan G. Davenport to develop viscoelastic dampers to absorb some of the sway. These viscoelastic dampers, used throughout the structures at the joints between floor trusses and perimeter columns along with some other structural modifications, reduced the building sway to an acceptable level.(p160–167)
At this point, I’m going to indulge in a bit of conjecture. I’m going to postulate a process that I will call “Inertial Confinement Ball Mill” (with the unfortunate acronym ICBM…) as the proposed mechanism for the “dustification” of the WTC towers.
The basic notion is pretty simple. Your mass is mostly in two rings, connected by flat mostly-concrete plates. Concrete nicely breaks up when hammered or stressed making stony bits. Crushing the cylinders with massive downward force will also tend to spall off bits and chunks. All of this is accelerating downward. At each story of compression, another load of stuff gets broken and added to the mess going down. But there isn’t really room for it, so some is pushed outward. The air inside is also compressed and pushed outward. Above the falling layer, a partial vacuum is formed as stuff passes by, so it tends to suck things back in. The result is a rolling motion of a mass of air with entrained debris. It can’t move outward fast since other stuff is in the way (it is confined by that inertial ring) and attempts to move outward that do succeed have some percentage sucked back in as the vacuum layer arrives. The chunks act as “balls” in a kind of a ball mill grinder, turning the floor plates and the contents of the floor into dust and chunks. The cylinder walls also get chewed up to some extent, but some chunks and beams fall as chunks. Note that the walls are constructed of chunks bolted together. I would expect those to separate at the bolts and have the wall fragment. It was designed for compressive loads, not tensile and grinding…
My thesis of the collapse of the WTC Towers is pretty simple. It violates no structural nor materials properties that I know of. The airplanes hit (larger and with more force than the design point impact) and destroy much of the wall structure where they impact. Much of the fire protective coating is knocked off by the impact. Fuel spreads over the entire floor and a massive fire starts.
The fire damages all the viscoelastic dampers such that sway and motion can increase and with an unknown effect on structural strength and fastener soundness (but “not good”…). Eventually the truss and spandrel steel is weakened enough by the prolonged heating that the remaining wall (already way over design stress from the impact removing sections of wall) starts to buckle. This lets the (modestly large number of…) floors above start to accelerate downward. This dynamic load vastly exceeds the static load from the same mass (the design support load) and so a progressive collapse begins.
As this mass continues to accelerate downward, the crushing and grinding at the cylinder edges begins progressively to consume the floor above the grinding zone while air currents and the gathering inertia of the mass of debris accumulating outside the crush zone prevents effective disbursal at the crush zone. This starts the process of the “inertial confinement ball mill” action that proceeds to effectively grind up substantially all of the concrete and aluminum and even some of the steel from the structure (not to mention desks, chairs, etc.) It is my belief you can see this happening in the videos of the collapse.
It is my opinion you need add nothing to that scenario to explain all the debris patterns and the lack of large intact structures on the ground.
Beyond that, for some of the more exotic odds and ends, you need to add some not-too-exotic additions.
1) Why didn’t it destroy the “bathtub” concrete basement on impact. We’re talking 500,000 lbs! The progressive collapse prevented simple acceleration. The mass impacts the next floor down that both moves that floor and slows the mass impacting from above. As it gets ground up, massive tonnage gets turned to dust and lighter debris that both scatters outward and has more air drag. Essentially, much of the mass lands slowly as dust and with minor impacts as modest sized bits, all of it slower than in a simple fall of a concentrated solid mass. Only about 20% of the mass of the building was metal structure (the rest concrete and similar non-steel bits), and most of the volume was empty air. Also note that the structure is strongest at the bottom, lightest at the top. The bottom is made to “take a punch” better.
2) It was 110 stories tall! Where is the debris pile!! Well, it is 110 stories tall of “mostly empty air”. The floors are made of concrete, mostly, and a light weight concrete at that. Largely ground to dust and scattered. The exterior walls are a very small volume compared to the building volume. Think of a beer can. A common party trick is to use an empty aluminum beer can, and carefully stand on it on one foot. I’m over 100 kg and it support me, so no worries. Then with a rapid “in and out” you thump the sides of the can with a finger from each hand on each side. You will find yourself standing on the ground. Under your foot is a VERY flat pancake that had been the can. So where is THAT debris pile? The WTC Tower design is very similar in structure vs volume…
3) There was only an 18 second impact recorded. That isn’t enough time for the building to even fall!!! It must be space aliens or energy beams!! Well, watch the film. MOST of the fall time is with a big top chunk mid air grinding its way down through structure. That will NOT show up as “impact on the ground” because it hasn’t done that yet. Sure, at the end the mass of cloud, dust, debris, and swirling grinder hits the ground. As expected. In about 18 seconds…
4) There were cars “toasted” blocks away next to unburned buildings and papers. Some with just the engines burned! Must be electromagnetic energy weapons!! Well, no. We had huge tonnage of aluminum and fuel burned at the airplane impact zone, then LOTS of heated steel and such. This gets broken to bits and some of them “spit out” of the grinder. The grinding itself adding energy, not cooling. There’s plenty of opportunity for burning hot lumps of steel, plastic, and aluminum (and who knows what all else mixed in) to land on cars and start them burning. The buses of today have lots of aluminum in the structure and once the furniture is ignited, it is often the case that the roof melts and / or burns. Similarly “engine fire” is THE most common car fire due to the engine being hot, full of fuel and flammable oil, and nowadays usually also made of aluminum that can burn. This is shown in the video as somehow special. It isn’t. Drop a flaming hot mixed lump of aluminum and steel on a car engine (puncturing the hood from downward velocity) and I would be astounded if it did NOT burn. Pointing at nearby unburnt paper is not very interesting either. Paper needs 451 F to burst into flame (per the book of that title) and it would be easy for an engine fire to NOT heat papers a few feet away to that temperature.
OK, with all that preamble, here’s the video
First off, h/t to LG here:
for asking me if I’d seen the video. I gave my “patterned response” about not needing explosives to bring down the WTC Towers due to the “beer can effect” and didn’t watch it.
Coming back later to watch, I found that, in fact, it has a Very Novel set of ideas about what happened and I found it “fun to watch”. Now I think the featured author (who is stated to be a Ph.D. Engineering so ought to know her stuff) was very careful about what she uses as data and what she allows to be assumed. But also I think she is not very well versed in dynamic phenomena.
It is my perception that she thinks in terms of static loads and simple falling structures, not dynamic forces of falling and inertial confinement or what happens when concrete is repeatedly hammered then put into a roiling air column. Similarly, there is a lack of appreciation of what a chunk of aluminum moving at 500 MPH can do to an aluminum sheathed steel wall. There is a reason the space station worries about being hit by a flake of paint. Speed matters to structural damage, perhaps even more so than the hardness of the impactor. Inertial confinement is a hard bitch at high velocity.
Also the way she sees fire seems more in the static mode. Not thinking of fire as an arson investigator does, a dynamic living things that can burn a person on a thick fabric wick over hours like a candle ( “spontaneous human combustion” that only happens to well clothed people near sources of ignition…) while not igniting the wood floor under them nor the couch next to them; yet can rush through a room in moment as a flash over, but not burning the floor…
So she reaches to an electromagnetic Tesla derived energy weapon. Even cites (some other name I couldn’t make out clearly from tiny speakers on the tablet) a patent from 100 years ago as the likely design. Leaving me to wonder if anyone hasn’t tried just building one from the patent… Ending at “The Hutchinson Effect” (hope I spelled the name right).
There’s a demo on a “solid chunk of iron” that I’m pretty sure is just a hollow box of iron, as it collapses inward which would violate conservation of mass in a real solid… So to my eyes it just looks like an inductively heated thin wall box distorts under magnetic load, but who knows…
In any case, this was the novel and interesting video that sent me on this path:
I give it extra points for original thought and entertainment value. (A demerit or two to the interviewer for claiming car engines are iron). Also extra credit for concept. A huge directed energy weapon, invisibly used, to take down the towers without anyone knowing. Ignore those airplanes and the hours long fires, they are just the “show” for cover…
So there you have it. I’ve put forward my “Crazy Idea” of an Inertial Confinement Ball Mill process coupled with weakening steel via fire. Feel free to poke holes in it if you like, or to post and comment on any other “wild and crazy idea” about what happened and what brought down the towers.
Lots of folks seem to like all the various theories, and I’m happy to have a place where you can relieve yourself of the burden of silence about it.
Just don’t expect me to let go of MY Pet Thesis just because yours is more interesting or prettier ;-)