9/11 Conspiracy Theories: How did WTC 7 collapse?

Experts from one of the few organizations with the experience and resources to perform forensic investigations of this kind examined the collapse. A relatively brief, mostly non-technical answer is here:

FAQs - NIST WTC 7 Investigation

Since I was asked to do so previously, I wrote my own description of their findings.

First, lets start with a video that shows the collapse from visible start of the collapse to finish.

It times the collapse at 18 seconds, many time slower than claimed by so called 9/11 “truthers”. The reality is that this 18 seconds is not really the whole collapse from start to finish, it’s just from when the collapse became visible to when it finished. The collapse itself started prior to the penthouse collapse, the penthouse collapse was just the first visible sign of the collapse from outside of the building .

So, what made WCT 7 collapse?

Let’s look at the floor plan for a typical WTC 7 floor:

Notice the arrangement of girders around column 79 near the lower left side of the image. You have girders running not quite diagonally from the exterior support columns to a girder that runs between column 26 at the top of the diagram to column 44 at the bottom. Columns 79, 80 and 81 are key for supporting these girders with column 79 playing a key roll with the support of the bottom half of those girders.

When WTC 1 collapsed, debris were scattered over a large area causing numerous other fires throughout the WTC complex. Fires were started over at least 10 floors in WCT 7 and burned out of control on floors 7, 8, and 9 and floors 11, 12 and 13. The fires burned out of control because the primary and backup water supplies for WTC 7’s sprinkler system relied on the city’s water supply and this was damaged in the collapse of WTC 1 and 2. These fires burned uncontested for nearly seven hours and spread to the northeast part of WTC 7.

Heat from the uncontrolled fires cause the steel floor beams and girders to expand. Eventually a girder on floor 13 lost connection with column 79, the unsupported girder along with other fire damage caused floor 13 to partially collapse causing a cascading series of floor failures from floor 13 to floor 5. This left weakened column 79 without horizontal support for a total of 9 stories resulting in it buckling, triggering a series of collapses upwards that reached the penthouse and caused the collapse we witnessed in the video linked above.

While this was the first external indication of collapse, internally WTC 7 collapse was well underway by the time the penthouse collapsed. This was followed by a series of structural failures involving columns 80 and 81 which were, with column 79, the columns that supported the interior of the East side of WTC 7. Following those column failures, the remaining interior columns collapse followed by the exterior columns. The fact that the exterior columns were the last to fail was the reason that the building appeared to collapse so quickly.

The diagram and information for this post is based on information found here: https://www.nist.gov/pba/questio...

Now, some common misconceptions that should be dispelled.

1. WTC 7 did not fall free fall. None of the WTC towers on 9/11 fell at free fall speed. Anyone claiming otherwise has not checked the facts or is simply repeating an oft repeated myth.
2. WTC 7 was damaged in the collapse of WTC 1 and numerous videos and pictures of the tower confirm fire and significant damage to the structure.
3. The fires burned uncontested for nearly 7 hours before the collapse.
4. Conspiracy mythologists often say WTC 7 was destroyed using controlled demolition. Controlled demolition requires:
1. Careful planning
2. Weeks of preparation
3. A patterned series of explosions for the final collapse

There is no evidence of a “synchronized pattern of explosions”. No such explosions were seen in any of the videos of the collapse (claimed explosions in videos were not in the pattern needed to clause a collapse and appeared after the collapse started so could not possibly have caused the collapse). No synchronized pattern of explosions was recorded (single randomly timed explosions could not have caused the collapse and have many other explanations), and no witness reports indicate there were synchronized pattern of explosions heard. Again, single explosions heard have many explanations and could not have caused the collapse.

To get around the unseen and unheard explosions, thermite and nanothermite have been proposed as possible alternatives. Reality is neither could possibly be explanations.

1. They cut vertically through steel beams while horizontal cuts through columns would be required.
2. There is no way to reliably control when the columns would be cut so that method could not produce the so called symmetrical fall of WTC 7.

Another problem which conspiracy mythologists ignore is that there is no way that anyone could have rigged the collapse of WTC 1 such that the collateral damage of the collapse would be sufficient damage WTC 7 and set it on fire to the point where fire could be seen as a viable cause for the collapse so it could then be rigged with explosives to cause the collapse.

Finally, there’s never been an explanation as to why whomever supposedly rigged WTC 7 to collapse would do that. None of the various wild assed justifications for 9/11 “inside job” theories explain why WTC 7 would need to be demolished particularly in a way that would expose the “inside job”.

From an engineering and scientific perspective, there is no need to use anything other than damage and fire to explain the collapse of WTC 7 and from a logical perspective, there was no need to collapse the building especially in a way that would expose an “inside job”

There is, however, a great benefit to 9/11 conspiracy mythologists to use WTC 7 as a smoking gun to bolster conspiracy myths that have been short on facts and sorely lacking support from individuals competent to evaluate the events of that day.

Point 1: I am a human and I question what I see with my intellect, my reasoning, my education and my experience so far on the planet. I am not a conspiracist or a truther, I’ll also not be labeled as either so you can dehumanize me thus taking away my freedom to discuss and call out chicanery and subterfusion. I do not hold bias, I am however well versed in the politics of the situation alongside the interests of the powerful and I am calling it out here. I was biased for the first four years believing the official story until I researched more into the events before, on and after September 11th.

Point 2: Let’s be honest here. NIST was forced into admitting that WTC 7 fell at freefall acceleration for 2.25 seconds which is 8 stories or 100 feet - with absolutely no structural resistance whatsoever, because thats what buildings do with nothing underneath them, they fall through the very engineered substrates that have held them prior to interference - very interesting but not very believable, well, not to those that have no skin in the game. https://www.europhysicsnews.org/...

Point 3: NIST refused (still continues) to refuse to test any debris for explosives under National Fire Protection Association standard code NFPA 921. No tests for explosives or incendiaries, not even to rule out the possibility that something untoward had happened or that OBL’s men might have also have interfered with a building as well as taking absolute control of the U.S. on 11th September 2001. To put another item into perspective the fact that “they” also successfully targeted the Pentagon (along with the full suite of WTC towers) with better than military precison leaves no question in my mind that there was collusion. You do not need peer reviewed papers to see through the many BS anomolies around this event (Suqami's passport being another).

Add to this the utterly asinine action of Defence Secretary Donald Rumsfeld post Pentagon attack running around the lawn in the apparent act of helping the injured, ie., when he was most needed as Secretary of Defense to co-ordinate, delegate and mobilise. He was uncontactable for the best part of an hour when the most important decision making was required. This must have been either on purpose (to avoid decision making) or due to the fact that he knew that no more attacks were imminent (suddenly felt a pang of conscience). Either way, this man suffers no fools, is no fool himself but his actions on the lawn are not just a ruse for the strategically positioned camera but in fact a another glaring anomoly. Had this been in fact a real terrorist attack you would have had areas cordorned off from crash site to Alaska - the Secretary of Defense would not be on the Pentagon lawn running around hanging out of a stretcher trying to look busy and interested, even caring. The press were welcome photograph Rummy as he dodged his duty - how was he sure that there were no more planes/missiles heading towards the Pentagon while his MIB were strategically placing airplane parts around the Pentagon lawn? - you do not fool me Donald, not one bit.

Point 4: Danny Jowenko (explosives expert) was adamant (before it was revealed what WTC7’s demise was) that it was a controlled demolition. If you see it as anything other then you probably believe in allmighty God so you are very likely a conditioned human being who loves a good yarn, superstition and a ‘God-like” conspiracy.

Point 5: Videos of collapse of WTC7 betray NIST’s model. It also looks like a controlled takedown, a perfect one at that, uniform and well executed. An attempt to reason a seat off with A2001 girder between columns 79 and 44, a beam expansion of 6.25 inches (revised on June 2012) causing a seat off, then column 79 buckling and ultimately a global symmetrical collapse, is at best fanciful, at its heart absolute and utter gibberish. These are computer models only, remodeled to make it work. They knew better to chance creating a scaled model as it would be well out of the bounds of functioning and accepted science/ engineering methods along with such improbable material behaviours.

9/11 Valid Experiments which refute the official story

9/11 Experiments: Eliminate the Impossible

Point 6: NIST refused FOIA (Freedom of Information Act) requests to divulge essential data to engineers and architects interested in learning more about the impossibilities surrounding the take down of WTC7. If you had nothing to hide you would release all information if to do nothing but put to bed some of those credible alternative theories (not all but the more relevant ones) - we also have science and engineering dressed up as a wolf in sheeps clothing, baa baahing and bleating their ridiculous theories (including crush up, total collapse induced by fire, and freefall for 2.25 seconds) to a docile public.

Point 7: Omission of girder stiffeners on Frankel Drawing #9114 and also omission of lateral support beams (three) on 13th floor G3005 beam in calculations.

https://www.ae911truth.org/image...

Point 8: Here is the Europhysics paper summation regarding what believable and real science and engineering have come to regarding their findings:

Conclusion

It bears repeating that fires have never caused the total collapse of a steel-framed high-rise before or since 9/11. Did we witness an unprecedented event three separate times on September 11, 2001? The NIST reports, which attempted to support that unlikely conclusion, fail to persuade a growing number of architects, engineers, and scientists. Instead, the evidence points overwhelmingly to the conclusion that all three buildings were destroyed by controlled demolition. Given the far-reaching implications, it is morally imperative that this hypothesis be the subject of a truly scientifc and impartial investigation by responsible authorities.

Steven Jones - Brigham Young University (early retired), Robert Korol - McMaster University (emeritus), Anthony Szamboti - Mechanical design engineer in the aerospace industry and Ted Walter - Architects & Engineers for 9/11 Truth – Europhysics, 14th September 2016, “15 years later: on the physics of high-rise building collapses” DOI: 15 years later: on the physics of high-rise building collapses

Does it not seem just a tad strange that shortly after this paper was published that a second global collapse occured in Iran with the Plasco building after it burned for a number of hours on 19th January 2017. There also appeared to be machines bucketing out molten metal from the base of this tower during cleanup. Sniff sniff, yep, I am smelling it again…

Point 9: We have yet to have a scientific, impartial, unhindered and believable investigation by responsible authorities. This fact alone should send alarm bells ringing as toward the true nature of said responsible authorities in control of the U.S. There is something very wrong here, with accountability, plausibility, ownership and honesty. What are they hiding and why not make the process of discovery transparent? - after all they could not have made more of a thames of the full process of investigation by covering up the glaring anomolies.

Point 10: This is what you are up against when you compare makeup engineering and science against reality, i.e., real v’s fake. Both reports were generated for Europhysics.

The metrics of both papers say a lot. In the fake science and engineering report we have (as of now) received 2032 views from the Europhysics website. In the real & responsible questioning report we have 636,268 views from the same website. People appear to be very interested in finding out more regarding the events surrounding the 11th September 2001 - I wonder why?.

Fake science and engineering report… https://www.europhysicsnews.org/...

v’s

Real and responsible science and engineering report… https://www.europhysicsnews.org/...

Point 11: A quote amongst quotes…

“When you bring together the national security state and the military -industrial complex, when you bring together the prison-industrial complex and all the profits that flow from it, when you bring together the corporate media multiplex that don’t want to allow for serious dialogue... and then, when you bring together the Wall Street oligarchs and the corporate plutocrats, and they tell any person or any group, 'If you speak the truth, we’ll shoot you down like a dog and dehumanize you the way we did to dehumanize the brothers in Attica,' the only thing that will keep you going is you better have some love in your heart for the people.”

Cornel West - American philosopher, political activist, social critic, author, “Race Matters”, April, 1st 1993, Cornel West Quotes (Author of Race Matters) (page 3 of 3)

Point 12: Why do we as humans fail to see patterns in life that spell interference in our progression as citizens of the world by hegemonists - why do we not call out such deviants?, if we understand plots, schemes and underhand dealings then we should be able to spot pretexts that are “enablers”, thus providing the cushioning to prevent e.g., a fall “into arms of America” as quoted from Bullet the Blue Sky a tune from U2. based on a trip to El Salvador, one of the many countries the U.S. destroyed through negligent interference. https://www.globalresearch.ca/hu...

Point 13: The U.S. appears to be a democracy but in fact it seems to be a oligarchy with elements of juntaism thrown into the mix. Are the constant wars of aggression that spur positive international regeneration through band aid military industrial, corporate, FED, CIA interference needed for international peace? - have they ever worked in El Salvador, Vietnam, Somalia, Iraq, Guatemala, Iran, Afghanistan, Chile, Bosnia, Nicaragua, just some of the 80 odd countries that were affected?.

Do we not see that pretexts JFK, 9/11, Gulf of Tonkin, USS Cole, are needed to stun us emotionally, intellectually, monetarily?. If I was to tell you that there have never been a war of aggression against the worlds only current superpower, ever, would you believe me? - I doubt it, but it is a fact. https://www.globalresearch.ca/th...

Once we have been “dusted” by the opium of salvation shrouded in “a democrative war on this, that and the other” and further administered as a suppository while we sleep (through our awakening) we will never be in a position to ever effect change, to remove sociopaths from their lair, their lies from their pulpit of deception.

The only salvation we have is to challenge the BS narrative we hear daily through AIPAC, Global Politics, Time, CNN, NBC, FOX, Newsweek, stopy buying their products and stop taking out loans and stop paying our taxes to fund such aggressive terrorism packaged up as democrative salvation.

Let us never forget that the U.S. dropped two nuclear bombs on Japan, killing many thousands of innocents. They also fire bombed cities night after night killing thousands upon thousands of innocent citizens. They are capable of anything given this fact. As for Vietnam, well Agent Orange was their chemical weapon here, forget Saddam or Assad as they both learned from the absolute master, the U.S. military Junta and their international secret service henchmen.

Let us also not forget the false flag reason the U.S. went in to WW1, this reason being a ship called Lusitania for which its last journey was in direct contravention of the rules of war at the time (the Cruiser Rules and Hague Conventions) so in effect; the RMS Lusitania which was carrying a considerable amount of ammunition, explosives, and other war material supplies for the armies of France and England, became a direct target for the German U- boat.

The U.S. MIB knew exactly what they were doing, they needed a pretext and a gullible public. The pretext and gullible public are the two constants needed for wanton continuing conflict and to keep the world in perpetual turmoil, service its 1000 military bases and the siphoning off of peoples taxes for the next generation of control devices. History has a nasty habit of repeating itself. Conditioned folk have a habit of listening to their jargon and believing it.

The disbelief with regards to the official 9/11 story is not locally harboured between a small group of folk that have nothing better to do but create “conspiracies” - the unanswered questions do not originate from people who feel as if they have no control of anything else in their lives bar confirmation bias towards their entitled investigations and the deafening silence that eminates from the absolute lack of honest and transparent investigations. Millions in the U.S. and worldwide are adamant that something is really wrong here.

Belief in govermental institutions has never been lower and as the old adage goes “where there's smoke there's fire” - in fact the fires that burned underneath ground zero burned like lava right up until the 20th December 2001.

The truth is that we don’t know what caused the collapse of WTC7—but the poor scientific quality of the official investigation makes the need for new investigations obvious, and the quality of argument of the advocates of the controlled-demolition theory is far, far, better than is the quality of argument of the very few people who are willing to put in any time defending the official reports.

It’s interesting that Mr. Fletcher invokes first and foremost a non-technical answer to a highly technical question.

Then Mr. Fletcher conflates the collapse of the penthouse with the collapse of the building. The penthouse and the building are two different structures. Mr. Fletcher apparently believes that the penthouse collapse was caused by a partial floor failure at the 13th floor, and that the east end of most of the 40-something floors of the building collapsed internally to the structure—without breaking through the external structure, without making any noise. How do 40 concrete floors crash into each other without making any noise? Mr. Fletcher does not explain that.

Mr. Fletcher repeats his boilerplate claims that fires at WTC7 burned out of control and burned for 7 hours. He provides no pictures of these fires—for good reason, because the pictures show that the fires were wimpy, and because the first photo evidence of fires was at noon, and the persistent fires weren’t photographed until after 2:00.

Mr. Fletcher’s claim that “WTC 7 did not fall free fall” (sic) is contrary to the government’s report that acknowledges 2.25 seconds of pure freefall in the collapse.

Mr. Fletcher’s claims about building demolitions are based on commercial building demolition practices. Military demolitionists who do not have the concerns about wide-ranging dust clouds or damage to adjacent buildings and do not need to salvage the copper plumbing can operate on an accelerated timescale.

In any case, since the government claims a failure at floor 13 caused the collapse, and since floors 14, 15, 16, and 17 were vacant, there was ample opportunity for a controlled demolition installation.

The total, symmetrical, and near-freefall collapse of WTC7 is evidence of synchronized column failures. The proposition that synchronized failures were incited by damage at the extreme eastern edge of the core structure defies credulity.

Contrary to Mr. Fletcher’s claims, thermite has been demonstrated to be capable of making horizontal cuts in vertical columns, as demonstrated by Mr. Jonathan Cole many years ago.

Mr. Fletcher’s notion that electric igniters could not set off thermitic charges with precise time controls is evidence-free. Practical people know different.

Contrary to Mr. Fletcher’s claim, many people have plausibly explained why an “inside job” op might include the demolition of WTC7.

It is interesting that Mr. Fletcher does not cite any particular “engineering and scientific” authority to support his claim that fire and damage explain the collapse of WTC7. Many scientists and engineers are willing to put their personal reputations on the line to call for new investigations. It seems that the “engineering and scientific” community must rely on amateurs to defend the official reports.

Conspiracy Theories?

Many enquirers have been clever enough not to ‘give’ any ‘theory’, what they did was just to ask questions instead of putting up ‘theories’ (we have theories when some facts are missing, otherwise these won’t be theories any longer, will be ‘facts’).

However, there are many facts, backed by numerous scientists without any political agenda before their investigations, without any answer:

(only from scientific angle, without ‘who did it?’ ‘how?’ etc)

1. Free fall. (NB the 3 seconds from start of free fall to end was correctly timed, not adding time prior to the start! as one answer did) We are not even arguing if the collapse is possible, but the way it collapse.
2. 100% horizontal fall, more perfect than most “controlled demolitions”. Rather unusual because the building would most likely to fall on one side than ‘100 symmetric’!
3. Is the collapse possible? （Again, just ‘yes’ ‘no’ without the ‘free fall’ and ‘perfect horizontal’)
1. Looking at other statistics of whole building collapsing only because of a fire. No evidence to support.
2. No plane crash on that building, Just fire?
4. Why did the news people and firemen etc already know the building is going to collapse soon when architect and engineers said that (collapse because of fire) is not possible?
5. If the collapse is due to the ‘fire’, why didn’t firemen sent to put out the fire?
6. Were ‘thermite’ (Thermite - Wikipedia) found? Well, if something was ‘found’ we cannot ‘un-found’ it, can we?

Just a few questions … better not add any more, otherwise I might be building up ‘conspiracy theories’.

How did it collapse? Free fall and completely horizontal, in appearance, quite like a “controlled demolition” (not saying it is, otherwise I might be labelled as a “conspiracy theorist”)

It collapsed symmetrically, in seconds, at nearly free fall speed. Its collapse was announced on both BBC and CNN a half hour before it happened. While BBC was reporting on its collapse (amazingly, with the building visible behind the reporter’s head as she discussed its collapse), the live feed went dead “due to technical problems”. Nearly as amazing as the collapse itself, was the fact that the collapse was reported before it happened. What does that say?

As far as “why” it collapsed - well, let’s just say it happened due to fire (perhaps aggravated fire) and damage to the building’s facade. Yes, I know that steel frame building don’t ever collapse due to fire and damage to the facade, but this one did, ok? So, please stop asking questions about it and just accept that it collapsed, and it collapsed symmetrically, at free fall speed. At least WTC 7 left some rubble, unlike WTC 1 and 2, which essentially disappeared, turning into dust and blowing in the wind, so to speak. How do you explain that? Those were some bad-ass terrorists that learned how to make the tallest steel-frame buildings in the world just “disappear”. For so many years, demolitions firms have been charging untold millions to demolish old buildings, which have to be carefully demolished… the process takes months and months… and here these guys come along… the whole thing just crumbled and blew away. Amazing!

In the future, when we want to remove eye-sore skyscrapers in order to build new ones (buildings, not eye-sores), why don’t we just get some old 747 that is at the end of its lifespan, fill it up with fuel, and crash it into the skyscraper using drone technology, and we’ll just watch as the building burns for a half-hour before collapsing/turning into dust. It was so easy - there was no rubble, no plane, no body parts… just fine fine dust.

Controlled demolition.

I invite all those who support the NIST explanation of “fires” to answer this question:
Using videos only and with reference to the cause, can you describe in your own words the process of collapse of WTC-7?

So far no engineers who support the official story have risen to the challenge - either to debunk the answer I give to the question using “controlled demolition” as cause or to present their own using “fires”.

Nor have they answered this question: WTC-7 showed few signs of fire at the time of its collapse. Can engineers explain why WTC-5, although ablaze, did not collapse, while WTC-7 did?

What can I say? Snookered!

… and just to add fuel to the “fire”, here’s a mathematician and former NIST employee expressing incredulity at the Emperor’s New Clothes nature of the NIST reports.

No one, conspiracy and anti conspiracy, is going to like this answer. No one knows actually and we may never know why WTC 7 failed the way it did. We do know now, that fires did not bring down WTC 7 thanks to the University of Alaska (UOA) Dept of Structural Engineering WTC 7 Evaluation. The NIST study, unlike the UOA study, was not open or peer reviewed and was therefore unscientific. NIST offshored the modeling and took 7 years to produce a report; long after the public lost interest in the specifics of 9/11. Why it took so long to create such a mediocre and closed study is a good question especially considering what we now know about what it takes to duplicate such work. The NIST study produced a computer model supporting the idea that a fire caused the collapse. The NIST study, given the two more accurate models of the fire damage produced by UOA, appears to be an amateurish endeavor, which only modeled a small section of the building. UOA produced two models that are more sophisticated than NIST’s. The new studies used two different modeling technologies and both clearly contradict NIST’s conclusions. There is no way the building collapsed the way NIST says it did. By the way, many of the NIST study’s details remain classified by the U.S. government and unavailable even to scientists.

Was there a flaw in the building caused by the existing basement substation that preexisted WTC 7 and brought down the building? Could shockwaves transmitted through an underground tunnel from WTC 1 and WTC 2 weaken the building? Did what appeared to be superficial damage to the corner opposite the fire contribute to the failure? These are among the possibilities still being studied by UOA.

The idea that maybe WTC 7 was not anchored properly given that it was built on top of an existing construction brings up the problem that many of the construction details concerning WTC 7 are kept locked away by the New York Port Authority and are unavailable to researchers. The New York Port Authority for its part is afraid of lawsuits originating from the families of 9/11 victims and is keeping everything that it can locked away.

NIST of course did not look at the possibility that WTC 7 was purposefully demolished and neither is the University of Alaska taking a look at demolition. The idea that the WTC 7 was brought down by demolition has been widely dismissed by experts however, maybe new information currently held as secret or confidential can be forced out of the government’s secretive hands by a court if lawsuits are engendered by the UOA study.

Yes, the building collapse looks suspicious but, it is not reasonable to expect anyone to prove a negative. That is why I say, at this point, more than 15 years later, we may never know why WTC 7 collapsed so neatly into its footprint.

A European study found what appeared to be military grade thermite in a dust sample from 9/11. NIST has questioned the origins and lack of control over the chain of possession of the sample. NIST however, declined when asked to independently study other dust samples from 9/11.

Here is how I think about it:

• Do I think the U.S. government is capable of coming up with such a cockemamie plan to crash planes into buildings and then covertly demolishes buildings full of people to create some kind of pretext for war? Well, there have been examples of Pentagon proposing crazy blatantly illegal and dangerous plans in the past that kill innocent people and even take American lives to create a pretext for war though not quite so bold as this and with such great loss of life.
• Does the collapse of the buildings look suspicious? Yes, very.
• Do I think the U.S. government is organized and competent enough to pull off flying planes into buildings and demolishing massive structures in a choreographed show? This is highly unlikely.
• Do I think the U.S. government could keep a secret about a plot to include hundreds of participants in a complex scenario to fly planes into buildings and then demolish them? This is even more unlikely.
• Do I think there is some kind of coverup? It is very likely that there are multiple coverups of government failures involving 9/11 but that does not mean the government perpetrated the plot. Yes, they probably covered up a lot of things because the government does cover up its incompetence all the time.

The government does need to take some responsibility for its behavior. The U.S. government caused the popularity of 9/11 conspiracy theories by acting like they were covering up things, looking as if they did something wrong, and they probably were covering up their own negligence and incompetence. The U.S. government always suffers from a lack of openness. Kind of like doing a Congressional investigation and then censoring a major portion of it and keeping it secret for 12 years. 9/11 was political failure by the Bush administration and lapse by the American intelligence services and no one suffered any accountability and that is a recipe for conspiracy theories to proliferate. The NIST study is just one more example of government incompetence feeding conspiracy theories.

5. How did the fires cause WTC 7 to collapse?

The heat from the uncontrolled fires caused steel floor beams and  girders to thermally expand, leading to a chain of events that caused a  key structural column to fail. The failure of this structural column  then initiated a fire-induced progressive collapse of the entire  building.
According to the report's probable collapse sequence, heat from the  uncontrolled fires caused thermal expansion of the steel beams on the  lower floors of the east side of WTC 7, damaging the floor framing on  multiple floors.

Eventually, a girder on Floor 13 lost its connection to a critical  column, Column 79, that provided support for the long floor spans on the  east side of the building (see Diagram 1). The displaced girder and  other local fire-induced damage caused Floor 13 to collapse, beginning a  cascade of floor failures down to the 5th floor. Many of these floors  had already been at least partially weakened by the fires in the  vicinity of Column 79. This collapse of floors left Column 79  insufficiently supported in the east-west direction over nine stories.