# Skyscrapers on fire, not collapsing **URL:** \ **Category:** Great Debates\ **Created:** [September 12, 2010, 10:53pm UTC](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541 "2010-09-12T22:53:57Z")\ **Posts on this page:** 20\ **Page:** 4
**Author:** ![Cisco](https://avatars.discourse-cdn.com/v4/letter/c/ccd318/32.png) [@Cisco](https://boards.straightdope.com/u/Cisco)\ **Post date:** [September 14, 2010, 2:35am UTC](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541/61 "2010-09-14T02:35:42Z")
> [@davidm](#): > > They were going on about how the cellphone calls made from the hijacked planes were impossible. One of them gave as a cite a series of experiments that supposedly proved that cellphone calls are impossible above 7,000 feet. I countered with a cite of a paper describing high altitude balloon experiments where they maintained a cellular connection up to 20,000 feet. The response was that _their_ paper was written by a Professor _Emeritus_ in Computer Science “so you know he’s not talking through his hat!” I have personally made a successful cell phone call from the top of Humphreys Peak, at 12,637’. ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [September 14, 2010, 2:44am UTC](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541/62 "2010-09-14T02:44:52Z")
> [@Cisco](#): > > I have personally made a successful cell phone call from the top of Humphreys Peak, at 12,637’. Not to aid CTers, but an unshielded person standing still is a different beast from a person moving at 500 MPH encased in a metal shell so far as cellphone communications are concerned. ---
**Author:** ![Naganeen](https://avatars.discourse-cdn.com/v4/letter/n/e95f7d/32.png) [@Naganeen](https://boards.straightdope.com/u/Naganeen)\ **Post date:** [September 14, 2010, 3:01am UTC](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541/63 "2010-09-14T03:01:15Z")
> [@Fear\_Itself](#): > > > [@Mozart1220](#): > > > > The buildings were designed to withstand airpcraft impacts, and 90% of the jet fuel burned in the initial explaosions. > > Cite? I am neither a structural engineer nor materials expert nor even a construction expert. My experience in large buildings such as these are limited to designing control systems for the HVAC, including a number of buildings surrounding the WTC site. But this one is easy enough to offer up since I had just rewatched the Nova documentary [**Why the Towers Fell**](http://www.boeing.com/commercial/airports/faqs/arcandapproachspeeds.pdf) (originally broadcast in 2002). During the documentary they interviewed Leslie Robertson extensively. Robertson was one of the chief structural engineers in the design of the World Trade Center. > [@](#): > > NARRATOR: Although drywall is indeed effective at keeping fire at bay, it has one serious drawback that would reveal itself on September 11th. It’s not very strong, especially when it’s been heated. > > The designers of the Trade Center tried to anticipate every possible disaster. The Towers were the first skyscrapers ever explicitly built to survive the impact of a plane. > > LESLIE ROBERTSON: We had designed the project for the impact of the largest airplane of its time, the Boeing 707, that is, to take this jet airplane, run it into the building, destroy a lot of structure and still have it stand up. Because I was curious, while I was watching the documentary the other day, I ran some very very rudimentary numbers. AA Flight 11, which crashed into the North tower, was a [767-200ER](http://en.wikipedia.org/wiki/Boeing_767#Incidents_and_accidents). Since the documentary wasn’t specific about which variant of the 707 was modeled, I assumed a [707-120B](http://en.wikipedia.org/wiki/Boeing_707#Variants). I also assumed, approximately 2/3s of Maximum Take Off Weight for each plane. I did assume different speeds, based on something I had heard during the discussions of why the towers fell. During the modeling of the impact of a 707 into the tower, the test assumed the impact would be an accident and that the plane would be flying at a relatively low speed ie. misdirected landing attempt. The didn’t envision a madman with the throttles redlined. I found a [Boeing Airport Reference and Approach Speeds](http://www.boeing.com/commercial/airports/faqs/arcandapproachspeeds.pdf) sheet for various Boeing aircraft and assumed approximately 140kt. ```auto PLANE MASS VELOCITY KINETIC ENERGY 707-120B 76,000kg 72m/s 197,000,000 joules 767-200ER 120,000kg 205m/s 2,522,000,000 joules ``` The building absorbed almost 13 times the amount of energy just from the impact of the plane than for which it had been designed. That does not include any of the effects of the fuel load, which had not been anticipated in the design and testing. > [@](#): > > LESLIE ROBERTSON: With the 707, to the best of my knowledge, the fuel load was not considered in the design. Indeed, I don’t know how it could have been considered. > > CHARLES THORNTON: They didn’t have the mathematical models in the computers to model a fire as a result of the fuel in a 707. I was asked in 1986 what would happen if a plane flew into the Trade Center. And I said it would not knock the building down from the pure physics of the mass hitting the building. But we…none of us really focused on that kind of a fuel fire. Charles Thornton is a structural engineer also interviewed for the documentary. Note: Takeoff weights were calculated from the values in the plane’s respective Wikipedia pages, quotes from [**Why the Towers Fell**](http://www.pbs.org/wgbh/nova/transcripts/2907_wtc.html) are taken from the transcript on the PBS website. ---
**Author:** ![Ale](https://avatars.discourse-cdn.com/v4/letter/a/f19dbf/32.png) [@Ale](https://boards.straightdope.com/u/Ale)\ **Post date:** [September 14, 2010, 3:16am UTC](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541/64 "2010-09-14T03:16:57Z")
> [@Magiver](#): > > Steel will always be king of the really tall buildings. > [@Cisco](#): > > Does anybody know how the Burj Dubai (name changed but I can’t remember to what; Burj Khalafi?) was constructed and how it would hold up to a similar attack\*? The Burj Dubai is made of steel reinforced concrete. 😉 Another thing about buildings that size falling sideways, won’t anyone think of Newton? The amount of force needed to accelerate a friggin’ 110 story building sideways is mind boggling. I’m not an engineer and have a hard time with math in general, but let’s say that we want one of the towers to topple sideways, as in it falls flat on its side. It comes to reason that the top of the building has to be accelerated laterally at the same rate it is accelerated downwards by gravity so it would travel the same distance sideways as downward in the same time, right? So, the force acting downward is equal to the weight of the whole building, ergo, the force necessary to accelerate it sideways so that it falls on it’s side as a fridge toppling over would have to be more or less equal to the weight of the whole building. From what I’ve read each WTC tower weighted 500.000.000 kilos, so you’ll need (bear in mind is a wild ass hypothetical scenario) at least 500 million kilos of force get it to land sideways. As a point of reference you could get that amount of force by sticking about **40** Space Shuttle solid rocket boosters (12.5 million kilos of thrust each) on the side of the building. Perhaps someone more number oriented than me could juggle the numbers more gracefully, but I think it serves to illustrate the argument of why big buildings don’t fall on their side. ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [September 14, 2010, 4:10am UTC](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541/65 "2010-09-14T04:10:20Z")
> [@Ale](#): > > I’m not an engineer and have a hard time with math in general, but let’s say that we want one of the towers to topple sideways, as in it falls flat on its side. It comes to reason that the top of the building has to be accelerated laterally at the same rate it is accelerated downwards by gravity so it would travel the same distance sideways as downward in the same time, right? So, the force acting downward is equal to the weight of the whole building, ergo, the force necessary to accelerate it sideways so that it falls on it’s side as a fridge toppling over would have to be more or less equal to the weight of the whole building. While true, you’re ignoring that there is something with the whole weight of the building acting on the building: The building. If I chip away at the base of a tree, it will likely fall over on its side. I didn’t fetch King Kong to push it over, I just let its own weight pull it down. The difference between the tree and the WTC buildings, is that a tree can’t be compacted in on itself. Once it starts falling, it doesn’t smash through its own stump. The stump is strong enough to keep supporting it, and so the tree stays aloft. But if it’s even the slightest bit off balance, it will start to lean, and from that point, its own weight is quite enough to make it fall. ---
**Author:** ![BayouHazard](https://avatars.discourse-cdn.com/v4/letter/b/d78d45/32.png) [@BayouHazard](https://boards.straightdope.com/u/BayouHazard)\ **Post date:** [September 14, 2010, 4:42am UTC](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541/66 "2010-09-14T04:42:03Z")
I would be way more willing to buy “Our government let 9/11 happen deliberately,” than “Our government blew the buildings up.” Intelligence failure IS the simplest explanation-stupidity usually is; but I would believe it this side of possible the hijackers were **allowed** to fly the planes into the buildings. If documentation that 9/11 was allowed to occur comes out when I hit 65 or so, I will be one unsurprised and grimly satisfied old person. As far as the heat potential… I was working a jobsite, and a hydraulic trash compactor caught fire. By the time the fire department got there, the flames were 30 feet high, and the heat was spalling the concrete wall behind the compactor. I believe that takes around 1100 degrees-and, y’all know, those planes had hydraulic fluid and jet fuel, which then got splashed onto all sorts of paper and hot-burning goodies. The support structures melting enough to give way is just the simplest explanation here. Iron oxide and aluminum being present? paint, rust, anti-rust paint, plane parts are made of aluminum, all sorts of sources for those materials. ---
**Author:** ![Cisco](https://avatars.discourse-cdn.com/v4/letter/c/ccd318/32.png) [@Cisco](https://boards.straightdope.com/u/Cisco)\ **Post date:** [September 14, 2010, 4:53am UTC](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541/67 "2010-09-14T04:53:41Z")
> [@BayouHazard](#): > > I would be way more willing to buy “Our government let 9/11 happen deliberately,” than “Our government blew the buildings up.” > Intelligence failure IS the simplest explanation-stupidity usually is; but I would believe it this side of possible the hijackers were **allowed** to fly the planes into the buildings. > > If documentation that 9/11 was allowed to occur comes out when I hit 65 or so, I will be one unsurprised and grimly satisfied old person. I read an explanation online once of why this was unlikely. I don’t know how accurate this is or how many holes could be poked in it, so take it for what it’s worth. Basically, from what I remember, the argument went roughly like this: The way intelligence gathering works, some 20-something kid would probably be the first to know about this. I believe we’re assuming things like communication intercepts and reception of annonymous tips here (how else would we find out about it?) He would tell his boss (or bosses), who would tell their boss (or bosses), repeat several times before it gets to the top. By the time it gets to the president, far too many people know to keep them all quiet. ---
**Author:** ![Ale](https://avatars.discourse-cdn.com/v4/letter/a/f19dbf/32.png) [@Ale](https://boards.straightdope.com/u/Ale)\ **Post date:** [September 14, 2010, 5:06am UTC](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541/68 "2010-09-14T05:06:05Z")
> [@Sage\_Rat](#): > > While true, you’re ignoring that there is something with the whole weight of the building acting on the building: The building. > > If I chip away at the base of a tree, it will likely fall over on its side. I didn’t fetch King Kong to push it over, I just let its own weight pull it down. The difference between the tree and the WTC buildings, is that a tree can’t be compacted in on itself. Once it starts falling, it doesn’t smash through its own stump. The stump is strong enough to keep supporting it, and so the tree stays aloft. But if it’s even the slightest bit off balance, it will start to lean, and from that point, its own weight is quite enough to make it fall. Yes, I’m aware of that and should had added it to my post but I was in a bit of a rush at the time. The reasoning I had and didn’t write up is that, unlike a tree, as you said, the building if tipped over would crumble on itself without falling sideways… that is, as they pretty much did. If you would want them to fall sideways like a box pushed over, then you need to move the mass of the building sideways with some external, more or less uniform force because it’s not going to leverage itself over the side. Just the simple lateral acceleration involved in moving sideways would disintegrate the building since you would have an acceleration gradient going from top to the bottom, trying to bend the structure. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [September 14, 2010, 5:21am UTC](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541/69 "2010-09-14T05:21:01Z")
> [@Frylock](#): > > No. I know there are tons of them. I figured it would be more efficient to ask for specific points about the specific questions I had rather than sifting through dozens or hundreds of threads at the rate of one search per five minutes. You are aware that you can search via Google or any other search engine without any delay, yes? Punch “site:boards.straightdope.com _search criteria_” into a search field and go to town. > [@Sage\_Rat](#): > > > [@Cisco](#): > > > > I have personally made a successful cell phone call from the top of Humphreys Peak, at 12,637’. > > Not to aid CTers, but an unshielded person standing still is a different beast from a person moving at 500 MPH encased in a metal shell so far as cellphone communications are concerned. Although I have not made a cell phone call from an aircraft, I have received voicemail via cellular signal at 20-odd thousand feet to a phone accidentally left in active mode. In fact, the reason airline passengers are instructed to turn off phones isn’t that they’ll interfere with aircraft communications (which are not only much higher signal power but also on a completely different frequency band) but because rapid switching between cells tasks cellular networks. The “metal shell” of the aircraft is effectively transparent to the microwave frequencies used by cellular networks, as is demonstrated by the hordes of passengers checking their phone messages and e-mail the moment the aircraft lands and starts to taxi to the jetway. > [@Rick](#): > > The walls inward / outward I understand. What I don’t understand is the thermite/mini nukes/wired for demo/ space ships and what ever else they have come up with. > It is obvious from the videos that the point of failure is the floor where the fires started. > Yet we get all of these crack pot stories. You know the old saw about how if you build something that is foolproof they’ll just build a better fool? Same thing with crackpots, only moreso. There is no damn fool theory so utterly implausible that you won’t find conspiracy theorists streaming out of the wainscoting to proclaim it to be the One And Only Truth. Stranger ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [September 14, 2010, 7:20am UTC](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541/70 "2010-09-14T07:20:27Z")
> [@Ale](#): > > The Burj Dubai is made of steel reinforced concrete. 😉 It depends on 110 million lbs of steel for structural integrity. ---
**Author:** ![Uzi](https://avatars.discourse-cdn.com/v4/letter/u/91b2a8/32.png) [@Uzi](https://boards.straightdope.com/u/Uzi)\ **Post date:** [September 14, 2010, 3:10pm UTC](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541/71 "2010-09-14T15:10:22Z")
> [@fuzzypickles](#): > > ETA: I’d like to see video of these supposed burning skyscrapers. I’d much rather see a video of the experiment you suggested to Mozart! ---
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [September 14, 2010, 3:40pm UTC](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541/72 "2010-09-14T15:40:22Z")
> [@Stranger\_On\_A\_Train](#): > > > [@Frylock](#): > > > > No. I know there are tons of them. I figured it would be more efficient to ask for specific points about the specific questions I had rather than sifting through dozens or hundreds of threads at the rate of one search per five minutes. > > You are aware that you can search via Google or any other search engine without any delay, yes? Punch “site:boards.straightdope.com _search criteria_” into a search field and go to town. I’m aware that people say that. 😉 But I almost never get any good results when I try it. It doesn’t seem like the index is very complete. ---
**Author:** ![Skywatcher](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/skywatcher/32/254_2.png) [@Skywatcher](https://boards.straightdope.com/u/Skywatcher)\ **Post date:** [September 14, 2010, 5:04pm UTC](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541/73 "2010-09-14T17:04:54Z")
> [@Mr.Miskatonic](#): > > > [@x-ray\_vision](#): > > > > [forthardknox.com is a custom short domain](http://forthardknox.com/2009/07/20/april-09-thermite-paper-not-peer-reviewed-published-in-journal-with-questionable-reputation/) > > And that says it all about that ‘paper’. Years and years of alleged ‘research’ and the truth movement still has to use a ‘pay to publish’ journal. > > The fun was when someone set up a program to write a scientific paper that was entirely random scientific word gibberish. Bentham accepted it for publication (pending the check clearing). And at least two Bentham editors have quit, claiming their employer had no integrity. One of them quit in the wake of the gibberish article. ---
**Author:** ![Skywatcher](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/skywatcher/32/254_2.png) [@Skywatcher](https://boards.straightdope.com/u/Skywatcher)\ **Post date:** [September 14, 2010, 5:07pm UTC](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541/74 "2010-09-14T17:07:18Z")
> [@Magiver](#): > > > [@Mozart1220](#): > > > > The buildings were designed to withstand airpcraft impacts, and 90% of the jet fuel burned in the initial explaosions. > > > > Even NY firefighters can be heard saying “It was like one of those controlled explosions, you heard pop, pop, pop, as the buildings came down”. > > > > If you watched ANY of the several docs shown yesterday you had to have seen that clip. > > the popping sound would be the outer wall support beams snapping. And bodies hitting pavement. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [September 14, 2010, 5:17pm UTC](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541/75 "2010-09-14T17:17:51Z")
> [@](#): > > If I chip away at the base of a tree, it will likely fall over on its side. I didn’t fetch King Kong to push it over, I just let its own weight pull it down. The difference between the tree and the WTC buildings, is that a tree can’t be compacted in on itself. Once it starts falling, it doesn’t smash through its own stump. The stump is strong enough to keep supporting it, and so the tree stays aloft. But if it’s even the slightest bit off balance, it will start to lean, and from that point, its own weight is quite enough to make it fall. The compactification hardly even matters. If you had a tree the size of the World Trade Center, and you chopped away at one side of the base of the trunk, it still wouldn’t fall over sideways. It’d break up into pieces, and the pieces would fall more-or-less straight down. The only difference that the tree being solid would make is that the rubble pile would be bigger. ---
**Author:** ![Cisco](https://avatars.discourse-cdn.com/v4/letter/c/ccd318/32.png) [@Cisco](https://boards.straightdope.com/u/Cisco)\ **Post date:** [September 14, 2010, 5:43pm UTC](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541/76 "2010-09-14T17:43:51Z")
> [@Chronos](#): > > > [@](#): > > > > If I chip away at the base of a tree, it will likely fall over on its side. I didn’t fetch King Kong to push it over, I just let its own weight pull it down. The difference between the tree and the WTC buildings, is that a tree can’t be compacted in on itself. Once it starts falling, it doesn’t smash through its own stump. The stump is strong enough to keep supporting it, and so the tree stays aloft. But if it’s even the slightest bit off balance, it will start to lean, and from that point, its own weight is quite enough to make it fall. > > The compactification hardly even matters. If you had a tree the size of the World Trade Center, and you chopped away at one side of the base of the trunk, it still wouldn’t fall over sideways. It’d break up into pieces, and the pieces would fall more-or-less straight down. The only difference that the tree being solid would make is that the rubble pile would be bigger. Actually that happens to sequoia trees sometimes, and they’re only about 1/5th the height of the WTC towers, and presumably some far smaller fraction of the mass. I saw it in the Mariposa Grove near the south end of Yosemite National Park last year, and somewhere I even have a photograph of a plaque describing the phenomenon. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [September 14, 2010, 6:51pm UTC](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541/77 "2010-09-14T18:51:32Z")
Thanks, I was wondering whether any trees were actually tall enough for that to happen. ---
**Author:** ![Miller](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/miller/32/481_2.png) [@Miller](https://boards.straightdope.com/u/Miller)\ **Post date:** [September 14, 2010, 7:56pm UTC](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541/78 "2010-09-14T19:56:05Z")
> [@Mozart1220](#): > > After seeing these buildiings fall STRAIGHT DOWN into their own footprint exactly like controlled demolitions. > > It doesn’t take an expert to see that the odds of that happening once with buildings of this size are astronomical. Three times suspends belief. This is true. In fact, you’re pretty much required not to be an expert to see that. Because all the experts are pretty near unanimous that what happened to the WTC was nothing like a controlled demolition. ---
**Author:** ![Skywatcher](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/skywatcher/32/254_2.png) [@Skywatcher](https://boards.straightdope.com/u/Skywatcher)\ **Post date:** [September 14, 2010, 8:24pm UTC](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541/79 "2010-09-14T20:24:38Z")
> [@Miller](#): > > > [@Mozart1220](#): > > > > After seeing these buildiings fall STRAIGHT DOWN into their own footprint exactly like controlled demolitions. > > > > It doesn’t take an expert to see that the odds of that happening once with buildings of this size are astronomical. Three times suspends belief. > > This is true. In fact, you’re pretty much required not to be an expert to see that. Because all the experts are pretty near unanimous that what happened to the WTC was nothing like a controlled demolition. Hell, even the one demolition expert who the “Truth” Movement could find to agree with them regarding any controlled demolitons that day says the Towers _weren’t_! Then said he had no explanation for 7 after being told it was on fire for several hours. ---
**Author:** ![Cisco](https://avatars.discourse-cdn.com/v4/letter/c/ccd318/32.png) [@Cisco](https://boards.straightdope.com/u/Cisco)\ **Post date:** [September 14, 2010, 9:26pm UTC](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541/80 "2010-09-14T21:26:29Z")
> [@Miller](#): > > > [@Mozart1220](#): > > > > After seeing these buildiings fall STRAIGHT DOWN into their own footprint exactly like controlled demolitions. > > > > It doesn’t take an expert to see that the odds of that happening once with buildings of this size are astronomical. Three times suspends belief. > > This is true. In fact, you’re pretty much required not to be an expert to see that. Because all the experts are pretty near unanimous that what happened to the WTC was nothing like a controlled demolition. Actually, Miller, he’s right in a few ways. First, the odds _are_ astronomical. Divide 1 - the number of days on which jumbo jets were intentionally flown into supertall skyscrapers - by the number of days on which jumbo jets were not intentionally flown into supertall skyscrapers, and you will come up with a pretty staggering figure. Secondly, the collapses of the WTC towers were very much like controlled demolitions in one key sense-- that being that the exact same force brought them down: gravity. So we really should be applauding **Mozart1220** ’s largely correct post. [Previous page](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541.md?page=3) [Next page](https://boards.straightdope.com/t/skyscrapers-on-fire-not-collapsing/553541.md?page=5)