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There have been a lot of claims made about the circumstances surrounding the events of 9/11 and Building 7 in particular.

The central claim regarding Building 7, that I have heard personally, is that Building 7 fell in such a perfect fluid motion that its collapse had to be due to a controlled demolition. Furthermore since Building 7 wasn't hit by a plane directly, it is claimed that there can be no other explanation for how the building collapsed in such a seemingly controlled fashion.

Is there any evidence to support the claims that Building 7 was destroyed in a directly controlled fashion?

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debunking911.com has a nice section on WTC7. – Sjoerd C. de Vries Mar 28 '11 at 22:24
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This claim is usually accompanied by the assumption that '9/11 was an inside job'. Chomsky, who was certainly no friend of the Bush administration provides some good arguments against that assumption. – naught101 Nov 5 '12 at 4:24
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Why the downvotes? Seems like a fair question, and, at least, a popular answer. – Mark Rogers Dec 18 '15 at 17:45
    
Nobody was killed in the collapse of building 7, and it was damaged beyond repair. So if it was, that was helpful. – gerrit Jun 16 at 17:05
up vote 128 down vote accepted

No.

Fires ignited by falling debris (from WTC 1) are the sole cause of the WTC 7 collapse.

Short answer:

  • Debris from the collapse of WTC 1, about 350 ft. to the south, impacted WTC 7, igniting fires on at least 10 floors.
  • Other than starting the fires, the debris impacts were not a contributing factor.
  • Fires on six of those floors grew from the time of the debris impact (10:28:22 a.m.) and lasted until the building collapsed (5:20:52 p.m.).
  • After several hours, the heat absorption ability of the fire-proofing began to fail. The building's structural steel began to soak up heat from the fires.
  • A ''seated connection'' was used for some of the girders framed to interior columns. The girder was held by four "erection bolts" (''girders'' span between columns; ''beams'' span between girders).
  • A 13.7 m (540 in.) long W33x130 beam heated uniformly to 600 °C will expand along its length by 4.5 inches.
  • In doing so it will produce a lateral force of 6.9 million pounds (30.7 million newtons).
  • The four erection bolts resisting this force had a total shear capacity of 0.180 million pounds (i.e., 2.6 percent of the possible force).
  • By the time the girders reached 164 °C the four bolts had failed (i.e., torn in two, ripped apart, cleaved in twain, etc.).
  • With the failure of the bolted connection, further thermal expansion of the floor beams pushed a 13th floor girder, between Columns 79 and 44, off its seat.
  • The flooring system on Floor 13 subsequently failed, collapsing onto the floors below, resulting in the collapse of floors 12 through 6.
  • The floor collapse left more than 150 ft. of Column 79 without lateral support.
  • Without structure transferring load laterally, Column 79 buckled and failed.
  • The transfer of load, once supported by Column 79, overwhelmed the structural capacity of the other columns. They too failed.
  • After burning for 6 hours and 52 minutes, WTC 7 suffered a fire-induced progressive collapse. The building was completely destroyed.

Long answer:

1. Erection bolts are not structural connections

In a seated connection, the beam or girder was supported by the seat, which was welded to the column. Bolts were installed that fasten the beam or girder to the seat for erection purposes These erection bolts did not carry any gravity load; rather, they were installed to insure that the beam or girder was held in place during erection. NIST found no evidence that the girders or beams in WTC 7 were welded to the seats. In a similar way. an angle or plate was bolted to the top flange to prevent the beam or girder from twisting, but there was little restraint to bending in the plane of the beam. NCSTAR 1-9 Figure 8-21 Page 349 Consider the girder that spanned between Column 79 on the interior of the building and Column 44 on the exterior. Thermal expansion of this girder would have loaded the erection bolts in shear, since (1) there were no shear studs anchoring the girder to the slab (and thereby restraining elongation), and (2) the columns were prevented from lateral movement because they were embedded in the floor slabs which had considerable in-plane stiffness. Additionally, the expansion of floor beams that framed into this girder, because the framing was asymmetrical, tended to add additional shear load to the erection bolts. The combination of these two shear loads could have failed the bolts in shear. If the erection bolts were to fail, then there would be no positive attachment preventing the girder from being pushed off the seat. Source: (NCSTAR 1-9) VOLUMES 1 and 2, page 348.

2. Thermal expansion will break stuff

The first failures observed were of the shear studs, which were produced by axial expansion of the floor beams, and which began to occur at fairly low beam temperature of 103 °C. Axial expansion of the girder then led to shear failure of the bolts at the connection to Column 79; and, at a girder temperature of 164 °C, all four erection bolts had failed, leaving that end of the girder essentially unrestrained against rotation. Continued axial expansion of the floor beams pushed the girder laterally at Column 79, as shown in Figure 8-26, in which failed shear studs and bolts were evident. When the beam temperatures had reached 300 °C, all but three shear studs in the model had failed due to axial expansion of the beams, leaving the top flanges of the beams essentially unrestrained laterally. Continued axial expansion of the girder caused it to bear against the face of Column 79, generating large axial forces that led to failure of the bolts connecting the girder to Column 44. When the girder temperature had reached 398 °C, all four erection bolts at Column 44 had failed, leaving the girder essentially unrestrained against rotation at both ends. After failure of the erection bolts in the seat at Column 44, continued axial expansion of the floor beams pushed the girder laterally, where it came to bear against the inside of the column flange. Axial compression then increased in the floor beams, and at a beam temperature of 436 °C, the northmost beam began to buckle laterally. Buckling of other floor beams followed as shown in Figure 8-27(a), leading to collapse of the floor system, and rocking of the girder off its seat at Column 79 as shown in Figure 8-27(b). The collapse process took time to occur in the LS-DYNA analysis, during which the temperatures had ramped up to their maximum values in the simulation. Source: (NCSTAR 1-9) VOLUMES 1 and 2, page 352.

3. Collapse Initiation

The simple shear connection between Column 79 and the girder that spanned the distance to the north face (to Column 44) failed on Floor 13. The connection failed due to shearing of erection bolts, caused by lateral thermal expansion of floor beams supporting the northeast floor system and, to a lesser extent, by the thermal expansion of the girder connecting Columns 79 and 44. Further thermal expansion of the floor beams pushed the girder off its seat, which led to the failure of the floor system surrounding Column 79 on Floor 13. The collapse of Floor 13 onto the floors below-some of which were already weakened by fires-triggered a cascade of floor failures in the northeast region. This, in turn, led to loss of lateral support to Column 79 in the east-west direction over nine stories (between Floors 5 and 14). The increase in unsupported length led to the buckling failure of Column 79, which was the collapse initiation event. Source: (NCSTAR 1-9) VOLUMES 1 and 2, page 611.

4. "Free fall" is a myth

To further clarify the descent of the north face, NIST recorded the downward displacement of a point near the center of the roofline from first movement until the north face was no longer visible in the video. Numerical analyses were conducted to calculate the velocity and acceleration of the roofline point from the time-dependent displacement data. The instant at which vertical motion of the roofline first occurred was determined by tracking the numerical value of the brightness of a pixel (a single element in the video image) at the roofline. This pixel became brighter as the roofline began to descend because the color of the pixel started to change from that of the building façade to the lighter color of the sky.

The approach taken by NIST is summarized in NIST NCSTAR Report 1A, Section 3.6, and detailed in NIST NCSTAR Report 1-9, Section 12.5.3.

The analyses of the video (both the estimation of the instant the roofline began to descend and the calculated velocity and acceleration of a point on the roofline) revealed three distinct stages characterizing the 5.4 seconds of collapse:

  • Stage 1 (0 to 1.75 seconds): acceleration less than that of gravity (i.e., slower than free fall).
  • Stage 2 (1.75 to 4.0 seconds): gravitational acceleration (free fall).
  • Stage 3 (4.0 to 5.4 seconds): decreased acceleration, again less than that of gravity.

:This analysis showed that the 40 percent longer descent time—compared to the 3.9 second free fall time—was due primarily to Stage 1, which corresponded to the buckling of the exterior columns in the lower stories of the north face. During Stage 2, the north face descended essentially in free fall, indicating negligible support from the structure below. This is consistent with the structural analysis model, which showed the exterior columns buckling and losing their capacity to support the loads from the structure above. In Stage 3, the acceleration decreased as the upper portion of the north face encountered increased resistance from the collapsed structure and the debris pile below. Source: Questions and Answers about the NIST WTC 7 Investigation.

NCSTAR 1-9 Figure 12-77 Page 603

Claims, assertions and questions :

Many of the claims and assertions by WTC 7 conspiracy theorists can be found at WTC 7 Draft Reports for public comment. The submission by Richard Gage of Architects & Engineers for 9/11 Truth is a good representation of how 911 conspiracy theorists rely on a lack of evidence to somehow draw conclusions (see: argument from ignorance).

Investigation by the National Institute of Standards and Technology*:

The National Institute of Standards and Technology (NIST) is responsible for conducting fact-finding investigations of building failures that resulted in substantial loss of life or that posed significant potential of substantial loss of life.

Final Report on the Collapse of World Trade Center Building 7 (The results of all NIST WTC investigations can be found at : NIST and the World Trade Center)

NIST: Questions and Answers about the NIST WTC 7 Investigation

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...

How hot did WTC 7's steel columns and floor beams get?

Due to the effectiveness of the spray-applied fire-resistive material (SFRM) or fireproofing, the highest steel column temperatures in WTC 7 only reached an estimated 300 degrees C (570 degrees F), and only on the east side of the building did the steel floor beams exceed 600 degrees C (1,100 degrees F). However, fire-induced buckling of floor beams and damage to connections-that caused buckling of a critical column initiating collapse-occurred at temperatures below approximately 400 degrees C where thermal expansion dominates. Above 600 degrees C (1,100 degrees F), there is significant loss of steel strength and stiffness. In the WTC 7 collapse, the loss of steel strength or stiffness was not as important as the thermal expansion of steel structures caused by heat.

Some people have said that a failure at one column should not have produced a symmetrical fall like this one. What's your answer to those assertions?

WTC 7's collapse, viewed from the exterior (most videos were taken from the north), did appear to fall almost uniformly as a single unit. This occurred because the interior failures that took place did not cause the exterior framing to fail until the final stages of the building collapse. The interior floor framing and columns collapsed downward and pulled away from the exterior frame. There were clues that internal damage was taking place, prior to the downward movement of the exterior frame, such as when the east penthouse fell downward into the building and windows broke out on the north face at the ends of the building core. The symmetric appearance of the downward fall of the WTC 7 was primarily due to the greater stiffness and strength of its exterior frame relative to the interior framing...

Graphic showing the buckling of WTC 7 Column 79 (circled area), the local failure identified as the initiating event in the building's progressive collapse

Did investigators consider the possibility that an explosion caused or contributed to the collapse of WTC 7?

Yes, this possibility was investigated carefully. NIST concluded that blast events inside the building did not occur and found no evidence supporting the existence of a blast event...

Is it possible that thermite or thermate contributed to the collapse of WTC 7?

NIST has looked at the application and use of thermite and has determined that its use to sever columns in WTC 7 on 9/11/01 was unlikely.

Thermite is a combination of aluminum powder and a metal oxide that releases a tremendous amount of heat when ignited. It is typically used to weld railroad rails together by melting a small quantity of steel and pouring the melted steel into a form between the two rails...

...Analysis of the WTC steel for the elements in thermite/thermate would not necessarily have been conclusive. The metal compounds also would have been present in the construction materials making up the WTC buildings, and sulfur is present in the gypsum wallboard used for interior partitions...

An emergency responder caught in the building between the 6th and 8th floors says he heard two loud booms. Isn't that evidence that there was an explosion?

The sound levels reported by all witnesses do not match the sound level of an explosion that would have been required to cause the collapse of the building. If the two loud booms were due to explosions that were responsible for the collapse of WTC 7, the emergency responder-located somewhere between the 6th and 8th floors in WTC 7-would not have been able to survive the near immediate collapse and provide this witness account.


*NIST is an agency of the U.S. Department of Commerce.

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@jon_darkstar The main towers did not fail from side impact. They failed because the truss hangers for the concrete floors seperated from their perimeter supports and the floor started dropping....bang, bang, bang...all the way down. Why straight down ? Gravity. – Rusty Mar 26 '11 at 22:34
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@jon_darkstar I can understand you might think that. Makes perfect sense. But the towers are not big poles. They are big boxes (an inner box and an outer box) and they are mostly hollow. The floors are basically just hanging between the boxes and when one comes off its hangers it can only go down. Down the inside of the box. – Rusty Mar 26 '11 at 23:03
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Gentle but firm reminder: comments are not the place for discussion, use the chat for that. Thank you. :-) – Sklivvz Mar 26 '11 at 23:09
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we can argue finer points of that forever, so lets not. return to the question at hand - building 7. can you propose any reasonable explanation for it that does not involve explosives? also, try to explain why the 911 Commission Report NEVER mentions building 7 in over 400 pages. Not a footnote. Nothing! @Sklivvz - sorry, read it right after – jon_darkstar Mar 26 '11 at 23:10
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You may want to show pictures of the SOUTH side of WTC7 prior to its collapse. Most conspiracy nutters neglect the fact that nearly 25% of the first ten floors were missing on the south side (they only, conveniently for themselves, show the north side of the building which faced away from the collapse). Check pages 59-66 of 911myths.com/WTC7_Lies.pdf – Larian LeQuella Sep 17 '11 at 3:39

Disclaimer

This answer relays observations and expert opinions related only to the narrow question of whether WTC 1, 2 and/or 7 were destroyed as part of a controlled demolition involving explosives.

This answer does not comment on the possibility of any conspiracy or involvement of any government nor any other such speculation.

Everything below is based on observed facts and credible expert opinions.

tldr; The use of the high explosive nanothermite to destroy the WTC towers on 9/11 is the theory most consistent with the evidence, and in particular it explains evidence that is inconsistent with the official theory.

In order to invalidate the above conclusion, one must refute or ignore all of the following:

  1. Statements by numerous reputable witnesses, including experts appointed by the U.S. Government, indicated the presence of molten iron;

  2. Reports concluding the presence of molten iron by numerous reputable agencies, including FEMA, a multi-national engineering firm commissioned by Deutsch Bank, numerous engineers, the NY Times;

  3. The conclusion of Dr. Harrit in a peer reviewed journal article that inactive, unreacted nanothermite was present on the steel of WTC-7;

  4. The presence of elemental sulfur;

  5. The oxidized and sulfidized steel from WTC-7 reported in an appendix to a FEMA report;

  6. The inability for kerosene (jet fuel) in general, and particularly in an open-air oxygen-starved environment, to reach temperatures hot enough to melt iron or steel;

  7. The opinions of thousands of engineers and architects who have signed a petition indicating their belief that an explosive was involved in the destruction of the WTC towers.

NIST has never commented on whether the incendiary and high explosive called nanothermite was or could have been involved in the WTC towers collapse.

In other words, the use of nanothermite to destroy WTC 1, 2, and/or 7 is not inconsistent with the official report of the U.S. government. NIST, and by extension the U.S. government, has simply never commented on the possibility.

After reading the explanation below, if still interested in knowing more about the theory about the use of nanothermites in the WTC towers, you may wish to read The Mysterious Collapse of World Trade Center 7: Why the Final Official Report About 9/11 Is Unscientific and False by professor of philosophy, David Ray Griffin.

Thermodynamics, 2nd law

A key to the demolition theory is the presence of molten iron and/or steel. Molten iron and steel is inconsistent with the second law of thermodynamics namely, which roughly in this context translates as: the heat created around a chemical reaction cannot be hotter than the maximum temperature of that chemical reaction.

Since kerosene (jet fuel) burns at a max of 1030°C in open air, and steel melts at around 2700°C and iron at around 1500°C, kerosene cannot create molten iron or steel without violating the second law of thermodynamics.

Molten Iron and Steel: Witnesses

There are numerous eyewitness accounts of molten iron or steel. These include video of what appears to be molten metal dripping from the side of the WTC, as viewed in the linked YouTube video.

Dr. Abolhassan Astaneh, UC Berkley Professor of Structural Engineering and, according to Wikipedia, one of the leading structural engineers to investigate the collapse of the World Trade Center towers, said "I saw melting girders at World Trade Center".

Leslie Robertson, WTC Structural Engineer stated, "they pulled out the big block of concrete, and there was like a little river of steel, flowing ..."

Captain Philip Ruvolo, NYPD stated in front of others who were in agreement "You'd get down below, and you'd see molten steel. Molten steel running down the channel-ways. Like you were in a foundry. Like lava".

Ken Holden, director of NY Dept. of Design and Construction on C-SPAN 2, states "Underground it was still so hot that molten metal dripped down the sides of a wall".

Here is a photo of molten metal, from WABC-TV. The liquid flowing out of the buildings is identified by Gery Warner, PE and former engineer at Alcan Aluminum as molten iron.

WABC-TV Molten Lava from WTC 2

The NY Times: A Search for Clues in Towers' Collapse By JAMES GLANZ and ERIC LIPTON, Published: February 2, 2002:

Pieces of steel have also been found that were apparently melted and vaporized not solely because of the heat of fires, but also because of a corrosive contaminant that was somehow released in the conflagrations.

Perhaps the deepest mystery uncovered in the investigation involves extremely thin bits of steel collected from the trade towers and from 7 World Trade Center, a 47-story high rise that also collapsed for unknown reasons. The steel apparently melted away, but no fire in any of the buildings was believed to be hot enough to melt steel outright.

Another contemporaneous NY Times article (no longer available) stated "Steel members ... appear to have partially evaporated in extraordinarily high temperatures", and "Parts of the I-beam, once 5/8 inch thick, had vaporized."

Molten Iron and Steel: Physical Evidence

Credible reports indicating the presence of molten iron come from FEMA, a multinational engineering firm, numerous reputable engineers and professors who examined the physical evidence, and peer-reviewed journal articles.

There are numerous other credible sources, extensively documented in Griffin's book, starting at page 36.

In its report on WTC7 in May 2002, FEMA documents in Appendix C steel that has been melted and partially evaporated. That report states:

Evidence of a severe high temperature corrosion attack on the steel, including oxidation and sulfidation with subsequent intergranular melting, was readily visible in the near-surface microstructure.

The report “WTC Dust Signature Report: Composition and Morphology” prepared by multinational engineering firm RJ Lee Group for Deutsch Bank states:

Various metals (most notably iron and lead) were melted during the WTC Event, producing spherical metallic particles. Exposure of phases to high heat results in the formation of spherical particles due to surface tension. Figure 21 and Figure 22 show a spherical iron particle resulting from the melting of iron (or steel).

The presence of iron microparticles are a byproduct indicate the presence of molten iron. No other explanation has been brought forward for their presence (that I am aware of).

Presence of active, unreacted thermite

An undisputed, peer-reviewed paper entitled "Active Thermite Material Discovered in Dust from the 9/11 World Trace Center Catastrophe", by Niels H. Harrit et al., The Open Chemical Physics Journal, 2009, 2, 7-31, concludes:

Based on these observations, we conclude that the red layer of the red/gray chips we have discovered in the WTC dust is active, unreacted thermitic material, incorporating nanotechnology, and is a highly energetic pyrotechnic or explosive material.

There does not appear to be any plausible, competing theory that can explain the presence of nanothermites on the steel examined by Harrit.

Video documentary of experts

There is a video with a number of reputable experts, who comment on the possibility of the WTC tower destruction being a controlled demolition. The videos are here:

Experts Speak Out Videos

The videos posit that the WTC buildings fell by demolition, and addresses evidence that undermines the conclusions of the NIST report indicating that the buildings fell because of the airline collisions.

Expert opinions are presented by:

  • Structural engineers (William Rice, PE; Richard Humenn, PE - Chief Electrical Design Engineer for WTC; David Topete, SE; Steven Dusterwald, SE)
  • Mechanical Engineers (Anthony Szamboti, BSME; Gary Warner PE; Edward Munyak, PE)
  • Chemical Engineers (David Gregg, PhD, CE; Jerry Lobdill, BSChE; Robert Kim Ireland, BSChE, US Army Corps.; Adam Parrott, BSChE; Mark Basile, BSChE; Robert Kim Ireland, BSChE, U.S. Army Corps of Engineers)
  • Materials Science Engineers (Jeffrey Farrer, PhD)
  • Metalurgists (Jason Cheshire, BSChE; Kathy McGrade, BS, ME)
  • Explosives Engineers (Roland Angle, P.E., Green Beret)
  • Professors (Lynn Margulis, PhD, National Medal of Science; Niels Harrit, PhD, Associate Professor Emeritus at U. of Copenhagen)
  • Demolitions experts (Frank Cullinan, PE; Tom Sullivan)
  • Architects (David Childs, architect of WTC-7; Leslie Young)
  • Firefighters (Leslie Young)
  • Fire safety experts (Edward Monyak, PE)
  • Physicists (Robert Podolsky, MS; David Chandler, MS; Jonathan Barnett, Ph.D., Professor at WTI, Author of 2002 FEMA Appendix C Study on WTC 7 Steel; Niels Harrit, PhD Spectroscopy; Steven Jones, PhD)
  • Other scientists (Kevin Ryan, BS Chemistry; Robert Bowman, Lt. Col USAF Ret., Former Director Advanced Space Programs; Jonathan Barnett, PhD, FEMA; William Woodward, PhD (Yale), MA (Princeton), BA (Harvard))

The experts involved comment on the inconsistencies between the NIST report and the reality of the physics under their expertise, and in particular how the fall of the twin towers and WTC-7 is not consistent with known physics. Most of their arguments are set out above.

Many other experts appear to be in agreement. This includes a petition by engineers and architects that has 2,408 signatures at the time of this writing. The petition includes the language:

We believe there is sufficient doubt about the official story and therefore the 9/11 investigation must be re-opened and must include a full inquiry into the possible use of explosives that might have been the actual cause of the destruction of the World Trade Center Twin Towers and Building 7.

ESO Theory and Evidence

For further interest, a web-site has put together a list of videos as part of a documentary discussing evidence of the demolition theory, which includes:

  1. Rapid onset of destruction,

  2. Constant acceleration at or near free-fall through what should have been the path of greatest resistance,

  3. Numerous eyewitness accounts of explosions including 118 FDNY personnel,

  4. Lateral ejection of multi-ton steel framing members distances of 600 feet at more than 60 mph,

  5. Mid-air pulverization of 90,000 tons of concrete, and large volumes of expanding pyroclastic-like dust clouds,

  6. Isolated explosive ejections 20 to 60 stories below the “crush zone,”

  7. Total destruction and dismemberment of all three buildings, with 220 floors each an acre in size missing from the Twin Towers’ debris pile,

  8. Several tons of molten steel/iron found in the debris piles,

  9. Evidence of thermite incendiaries on steel beams,

  10. Nanothermite composites and iron microspheres found in WTC dust samples.

Summary

To be clear, and to repeat the disclaimer, there is no claim here regarding any conspiracy or involvement of the US government. It is tempting to make such a jump, but that would be purely speculative.

Concluding that the towers were destroyed by explosives does not necessarily mean the U.S. government participated or was complicit in such destruction.

The conclusion that nanothermites were involved in the destruction of the WTC towers is based on the observations of credible individuals, expert reports, and laws of physics.

The presence of nanothermites does not contradict the official NIST report and comments. According to Griffin's book (at p. 139), NIST has never commented on the possible use of nanothermites in WTC.

The NIST theory and explanation for the towers falling is inconsistent with evidence, namely the presence of molten iron and steel and the presence of nanothermites.

The use of nanothermites is the theory most consistent with the evidence to explain the fall of the WTC towers, particularly tower 7.

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Three small notes: Lynn Margulis, PhD, National Medal of Science winner was according to wikipedia an evolutionary theorist, taxonomist, bacteriologist, protistologist, and botanist, with advanced degrees in zoology and genetics. This does not mean she is an expert in this matter. I can find no evidence that David Childs, the architect of WTC-7 thought it was brought down by controlled demolition. – Legion600 Dec 17 '15 at 20:26
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Youtube link. I'm at work, dude. Also, video is easily faked or misinterpretated. And you don't address the other things either. Thermite still isn't an explosive and the laws of thermodynamics are irrelevant. – GordonM Dec 18 '15 at 14:55
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I'm not sure if I agree with any of this, but you definitely created and editted a nice looking and cited answer. I rescinded my downvote. The likelihood of a successful mass-conspiracy for reasons of human nature and socialization alone, seems infinitesimal. – Mark Rogers Dec 18 '15 at 18:02
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Sorry but I watched your video and it was just what I expected. Sinister bass chord, lots of "eyewitness testimony", lots of "experts" trotted out and no hard evidence at all. If there was a beam that resembled a stalactite then where is the photo of it? As for reports of rivers of molten metal, eyewitness reports are notoriously unreliable and there's always the chance that some other substance looks enough like molten steel that it would fit witness expectations. As for the thermodynamics thing, the report said "softened", not "melted" Plenty more to say on this but running out of space. – GordonM Dec 18 '15 at 18:45
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Steel doesn't need to be at the melting point to be malleable. In fact, it is well malleable below 1100C (en.wikipedia.org/wiki/Forging_temperature). At that point it bends easily and wouldn't be able to hold up the building. – Sklivvz Dec 21 '15 at 19:18

Yes, World Trade Center building 7 fell due to controlled demolition, there are many reasons why we can expect this to be so.

1.) Free fall speed was achieved after global collapse was initiated, indicating complete failure of all support structure.

This is an important point because it proves without any doubt that the failure of the central column could not account for the speeds attained by the failure of the rest of the building.

If any of the other columns in the building resisted gravity to any measurable degree, then the building could not have fallen at free fall speed, by definition. That would necessarily mean that the other 23 interior columns stopped offering any resistance to gravity after the single column under the east penthouse collapsed, and the collapse of all exterior walls initiated (The entire perimeter collapsed simultaneously).

To clarify, even if you accept that there was only free fall in "Stage 2" as NIST claims (Because they start counting when the penthouse falls.), everything I have said is just as valid because once global collapse begins, nearly every column that supported the perimeter walls must have been entirely (not partially) destroyed. Even only a handful of undamaged columns would have prevented free fall and likely would have resulted in asymmetric collapse.

In his video showing free fall collapse, David Chandler shows a margin of error of 0.456, or about 5%. This number I think is very pessimistic, but if we take it at face value, this means that if any combination of columns were able to withstand 6% of the force of gravity, this would have been measured. There were 42 columns in the building which account for the resistance to gravity. We will assume that every floor is at full load bearing capacity, that each has a safety factor of at least 2, and that they are all equally burdened.

Under this scenario, if half of the columns were destroyed, there would have been no collapse. If ~6% of the remaining 21 columns were undamaged, this would have resulted in asymmetrical collapse and/or a measurable decrease in the acceleration of collapse. That number comes out to 1.26. So it is beyond any shadow of a doubt that 3 or so undamaged columns would have prevented free fall to a measurable degree and/or an asymmetric collapse.

the New York Building Code of 1892 specified a safety factor of 4:1. -Pg. 172 Rise of the New York Skyscraper: 1865-1913

2.) The central column(s) failed first and rapidly.

It is clear from the fall of the penthouse that central columns in the building failed before global collapse. This is suggestive of controlled demolition for two reasons;

a.) It is common to destroy the central columns first to avoid collateral damage, and in this case would be done to avoid visibility.

b.) Falling debris did not damage the central structure of the building, and fires could not have destroyed, or targeted, column 79.

The initiating local failure that began the probable WTC 7 collapse sequence was the buckling of Column 79. -NIST NCSTAR 1A

Additionally, the column could not have failed rapidly. At best the central column could have been weakened by the fires, and initiated a slow collapse of the penthouse. (Though fires have never caused this to happen in history.)

This is because a hydrocarbon based fire will take about 7.5 minutes to get a room to 1000 degree's Celsius (Because of fireproofing, and steel's high thermal conductivity, it would take much longer to heat the steel to the temperature, if it happens at all). This gradual increase in temperature corresponds to a gradual reduction in strength and therefore a gradual collapse.

3.) Larry Silverstein was talking to his insurance company about destroying Building 7 in a controlled demolition, according to second hand witness Jeffrey Shapiro.

This would have been impossible to prepare that day, and suggests it had already been prepared before 9/11.

4.) Thermitic material was found in the dust of the World Trade Center building collapses, as well as iron spheres.

Iron spheres could only have been made by temperatures far in excess of the capabilities of diesel, jet fuel, or office fires (Except under highly controlled conditions). The evidence has been published in a peer reviewed journal seven years ago by professionals in their fields and has to this day never been refuted by another peer reviewed paper. In fact it has been corroborated by an independent expert Mark Basile.

5.) The building fell symmetrically.

The damage to building 7, if done by fire must have been stochastic which would not permit simultaneous global nearly instantaneous failure, and if it is postulated that the damage to the corner of the building initiated the collapse, then the building should have collapsed toward the direction of the damage.

Symmetrical collapse rules out either damage from fire or building debris as an explanation for building collapse.

6.) Buildings 3,4,5, and 6 did not collapse from either debris or fire.

This is despite being closer and taking significantly more damage. With the one exception that the core of building 6 collapsed. It is relevant to note that the center collapsing did not result in global collapse.

7.) When a debate was attempted no respectable scientists was found that would defend the official story about how the WTC fell.

On the side stating that the official story is physically impossible is David Griscom PHD with a Hirsch Index of 52. Harvard, Yale, MIT, CalTec, Stanford, Colgate, and the American Physical Society were contacted to come and debate him. No one accepted.

Since pre-meditated controlled demolition is currently the only theory that can explain free fall symmetrical collapse, the conversation by Silverstein, the iron spheres, and the thermitic material, one can safely say, at the very least, that controlled demolition of building 7 is currently the scientific consensus.

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I can see I have a hostile audience here. I enjoy the challenge, but I do wish you would let me know the reason for your down votes. Thanks. – user2699942 May 9 '14 at 23:34
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This is based on argument from ignorance. The fact that you or someone else can't explain some things, it does not mean they are impossible – sashkello May 10 '14 at 1:00
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I just downvoted, because I happened to read the last sentence. You are claiming to have scientific consensus? Bwuhahahaha! – Oddthinking May 10 '14 at 1:23
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You don't provide a reference for "Even only a handful of undamaged columns would have prevented free fall and would have resulted in asymmetric collapse." – user5582 May 10 '14 at 4:09
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"The rest of the criticism here is ad hominem." No, pointing out argument from ignorance is not ad hominem. No, pointing out the distinction between opinion and direct facts is not ad hominem. No, pointing out that the trustworthiness you implied by "peer-reviewed" was unwarranted is not ad hominem. No, pointing out that your claim of scientific consensus was laughable was not ad hominem (although, admittedly, merely gainsaying, not an argument). – Oddthinking May 10 '14 at 12:35

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