The Collapse of World Trade Center: The Complete Physics

[Oystein]

@econ41 , @Henkka :
Mendel, in post #10, reproduced NIST's summary of their collapse initiation scenarion.
Contains elements such as "creep" of core columns, load redistribution through hat truss, etc.

Read it again, read it carefully!

"Creep" is when the columns actually get shorter (and thicker) through plastic deformation short of buckling - because load increases and/or capacity decreases (e.g. due to increased temperature), and the steel no longer responds fully elastically to applies loads.

Henkka needs to understand that once a structure's capacity drops even a tiny bit below its (remaining) capacity and some first element fails, load redistribution makes the next elements fail in VERY rapid sequence, because load is redistributed at the speed of sound within the structural material (which, in steel, is several times the speed of sound in air). We are talking easily less than a second from first failure to last.

----

Think of a wire rope: When you increase load, or heat it while load remains the same, or increase load and temperature, at some point, a wire may snap, but the rope still holds - because locally, that wire may be overloaded, but other wires are yet below their capacity and can take up the load previously born by the one that tore.
Then another wire pops.
And another.
This can go on for a while - you may observe that the rope elongates a bit (creep), but it holds.

Until so many wires have popped that the rope's remaining capacity is just barely holding the load.
Then, when one more wire pops, the next and the next and the next follow immediately, and the rope tears as a whole in a tiny fraction of a second.


Source: https://www.youtube.com/watch?v=Jj_K6bGQIfM


---------

Once you see the top of the tower tilt, ALL columns except maybe some on the side of the perimeter away from where it tilts to, are already severed. At that poin ALL these dropping columns are already missing standing columns. (And within a very small fraction of a second later, the last columns are severed, too.

 

[Jeffrey Orling]

The plane impacts destroyed multiple columns interrupting the load paths from above. The loads redistributed to intact columns. This likely or could have caused the columns taking on new load to buckle. Collapsing slabs either destroyed the slabs they fell on... initiating a chain reaction. It seems to me that the failures were in the slab to column connections. The critical lateral bracing for the columns were beans in the core and slabs and trusses outside the core. When the lateral bracing is non or under performing... the columns they brace have diminished capacity and will buckle at some point. Collapsing slabs UNLOAD columns but also remove the critical lateral bracing. So the collapsing slabs are driving some column buckling. As no new loads are added... the understanding involves how loads were redistributed as a result of failed and under performing columns.
Assuming there was a runaway floor collapse... columns would see reduced loads but also red loss of bracing. Loss of bracing leads to buckling and loss of axial capacity.
The top "blocks" may likely have translated and destroyed axial load paths... leading to dropping / tilting top blocks. Essentially columns destruction led to a cascading or runaway load transfer / column failure scenario where the collective axial column capacity was driven below service loads. You lift one leg off the floor and the remain leg carries all your body weight. It can... but it can also collapse if you then are told to carry a heavy load. Two legs might allow it... one leg would collapse.
I see two basic processes in play....
1- runaway progressive floor collapse...leading to loss of bracing reducing axial capacity... leading to columns buckling and misalignment of end to end connections
2- load redistribution in perimeter core columns leading to a runaway/progressive under performance and collapse.

Simply put not enough reserve capacity was designed into the connections etc. I presume because they didn't envision a collapse going "runaway".... rather it being arrested.

 

[Henkka]

By the way, I wonder why all these educational videos use things like coke cans, some sticks etc. Clearly the idea is to "model" the physics involved in the collapse. But if that's what you want to do, why not just build a miniature tower? Like out of matchsticks and glue or whatever. Then damage the tower near the top, and show us how the "top block" accelerates smoothly through the undamaged portion below. It should be doable, right? But all we get are coke cans with a massive amount of extra weight put on top lol.

 

[Miss VocalCord]

By the way, I wonder why all these educational videos use things like coke cans, some sticks etc. Clearly the idea is to "model" the physics involved in the collapse. But if that's what you want to do, why not just build a miniature tower? Like out of matchsticks and glue or whatever. Then damage the tower near the top, and show us how the "top block" accelerates smoothly through the undamaged portion below. It should be doable, right? But all we get are coke cans with a massive amount of extra weight put on top lol.

Mick has been doing some tests with structures:

https://www.metabunk.org/threads/to...-the-collapse-of-the-wtc-towers-on-9-11.7396/

 

[econ41]

Well, I found the exchange:

I see that you are diverting from the explanations I presented.

As for the rest of your post with the diagrams, I don't know, I found it hard to follow/understand honestly.

I'm well aware that you 'don't know'. So I outlined the basis of explaining what actually happened. A starting point for discussion to give you opportunity to learn.
Maybe we could try again at a more suitable time and in a more appropriate thread.

 

[econ41]

@econ41 , @Henkka :
Mendel, in post #10, reproduced NIST's summary of their collapse initiation scenarion.
Contains elements such as "creep" of core columns, load redistribution through hat truss, etc.

My goal was to explain the relevant aspects of the Twin Towers collapse mechanism for @Henkka. In layperson understandable language and helped by use of valid simplified models. My focus on the main mechanism of the 'initiaion' stage i.e. the process of cascading failure of columns driven by load redistribution. Details such as 'creep' and the role of the hat truss I legitmately treat as 'black boxes'.

Read it again, read it carefully!

I'm familiar with the concepts and the NIST references. My SOP is to explain physics from ZERO base - not relying on NIST as authoritative.

"Creep" is when the columns actually get shorter (and thicker) through plastic deformation short of buckling - because load increases and/or capacity decreases (e.g. due to increased temperature), and the steel no longer responds fully elastically to applies loads.

Henkka needs to understand that once a structure's capacity drops even a tiny bit below its (remaining) capacity and some first element fails, load redistribution makes the next elements fail in VERY rapid sequence, because load is redistributed at the speed of sound within the structural material (which, in steel, is several times the speed of sound in air). We are talking easily less than a second from first failure to last.

You might want to reconsider that generalisation.

 

[Oystein]

By the way, I wonder why all these educational videos use things like coke cans, some sticks etc. Clearly the idea is to "model" the physics involved in the collapse. But if that's what you want to do, why not just build a miniature tower? Like out of matchsticks and glue or whatever. Then damage the tower near the top, and show us how the "top block" accelerates smoothly through the undamaged portion below. It should be doable, right? But all we get are coke cans with a massive amount of extra weight put on top lol.

A match-stic model is as bad a model of the tower as is a coke can - with the HUGE disadvantage that it is not actually available to anyone, plus it distracts from the simple point that was to be illustrated: That a slight disturbance, a slight bending-out-of-plum, of a vertical support readily leads to practically instant total loss of capacity.

This can be replicated by anyone with access to a beverage can.

In fact, I remember doing this as a teenager on the school yard during breaks. It was a way of demonstrating one's agility and balance:
- Place a can on the (flat, hard, even) ground, gently step on it,
- balance your entire weight, one-legged, on the top of the can,
- carefully, gently bend knee, bow low, till you can reach below the sole of your shue with your hand
- ever so slightly tip the side of the can
- Result: You squash it straigth down and perfectly flat immediately
I remember the first time I did this, how surprisingly light the tap only needed to be. In the video, it appears they are poking that stick deep into the side of the can, but really only a trivial tap, that you would not normaly expect to dent the wall of the can by more than a small fraction of a millimeter, already does the job. (And that is another nit-pick for the video )

I remember beverage cans to have been somewhat heavier, more stable back in the 1980s than they are today, so not sure if a teenager nowadays could still stand on one without squashing it first thing.

Anyway, point is, the coke can experiment is something you, I and the next person can do easily.

 

[Mick West]

I remember the first time I did this, how surprisingly light the tap only needed to be. In the video, it appears they are poking that stick deep into the side of the can, but really only a trivial tap, that you would not normaly expect to dent the wall of the can by more than a small fraction of a millimeter, already does the job. (And that is another nit-pick for the video )

Usually a little more, unless you are right up on the limits of the can - which is tracky to do while standing on it. Scale is always a problem.


Using three cans simplifies things a bit.


Lots more discussion about this, years ago:
https://www.metabunk.org/threads/ho...acceleration-for-part-of-wtc7s-collapse.8270/

 

[Scaramanga]

I don't think I support that conclusion.

The crucial factor is that the horizontal connectors connect the outer wall to the inner core. Once that connection is lost then the outer wall is just 1300 feet of precariously balanced steel, and the slightest buckling in it can lead to total instability. One basically has a chicken and egg scenario.....which comes first, the steel wall buckling or the connectors being lost. But really one has both. The walls were buckled, but the loss of the horizontal connectors to the main core allowed the structure rigidity to be lost, exacerbating that buckling.

 

[econ41]

@Scaramanga

Lets look at what I suggest is the main reason for @Mendel's concern:

I don't think I support that conclusion.

The crucial factor is that the horizontal connectors connect the outer wall to the inner core. Once that connection is lost then the outer wall is just 1300 feet of precariously balanced steel, and the slightest buckling in it can lead to total instability.

You are conflating separate and distinct stages of collapse. viz (a) the inwards bowing buckling of the perimeter in the 5 or 6 storeys of the impact and fire zone causing failure at that location. i.e.; the "initiation stage" of the collapse contrasted with (b) the toppling of the perimeter columns ofthe lower tower. AFTER the floor joist bracing was removed. Those perimeter columns then toppled in various sized sheets BUT without buckling.

The inwards bowing of perimeter columns ONLY affected the 5-6 storeys of the impact and fire zone. NOT the 1300 feet of the total tower. The 'precariously balanced' aspect only applied to the perimeter walls that remained standing unbraced, unsupported AFTER the fire and impacrt zone had failed, allowing the Top Block to fall.

Your original comment included this bit:

Scaramanga said:

The loss of the horizontal connectors allows the vertical beams to bend inwards or outwards....and the towers collapse.

You are jumping over a couple of stages with that conclusion 'and the Towerscollapse'. The only bit that failed from buckling was at that specific stage of 'initiaion'. Which led to the global collapse of the 'progression stage' - which did not involve buckling as a causal factor.

Hence - whether my reasons are the same as @Mendel's or not - I also 'don't think that I support his conclusion'.

Essentially those horizontal struts are the Achilles heel of the entire building.

But only when the building is subjected to gross trama a magnitude or more greater than it was designed to rewsist

One basically has a chicken and egg scenario.....which comes first, the steel wall buckling or the connectors being lost. But really one has both. The walls were buckled, but the loss of the horizontal connectors to the main core allowed the structure rigidity to be lost, exacerbating that buckling.

Two separate stages. The wall buckling occured in the fire and impact zone and was (probably) the trigger of the 'initiation stage'. The loss of horizontal connetors was critical to the 'progression stage'. Not relevant to initiation. In fact there has been contentious discusion over whether or not those connectors were strong enough to pull in the colmns >> a topic for another time.

 

[Landru]

Is there anything here that hasn't been discussed on Metabunk before?

 

[econ41]

Is there anything here that hasn't been discussed on Metabunk before?

There is nothing new that I am aware of other than the new video that defined the OP Topic, The issues of technical confusion that have flowed from the topic have all been addressed previously. Several times.

 

[Henkka]

A match-stic model is as bad a model of the tower as is a coke can - with the HUGE disadvantage that it is not actually available to anyone, plus it distracts from the simple point that was to be illustrated: That a slight disturbance, a slight bending-out-of-plum, of a vertical support readily leads to practically instant total loss of capacity.

This can be replicated by anyone with access to a beverage can.

Couple things... Firstly, my question was about these sort of educational videos and documentaries about the collapses. While it's nice that the soda can thing is something that anyone can do at home, obviously these videos can do so much more with the budget they have. For example, here is a video by Discovery UK:


Source: https://www.youtube.com/watch?v=4LFZA0Rx1gg


You can see that the production value is very high, with impressive digital animation to show the structure. Then they go into a lab to show how heat weakens steel, obviously not cheap either. And then at 7 minutes, they do the soda can thing... Like the whole point of the video is to do physical experiments that would help explain the collapse to laypeople. But they always neglect the most obvious experiment, which would be to just build a miniature tower and show how it can undergo a top-down, smooth collapse when damaged. And I think the reason for this is that such top-down collapses don't really happen in physical experiments.

Secondly about the soda can thing in general... I don't know if I need to point this out, but I'm pretty sure there wasn't a giant person stepping on the North Tower. The difference in mass between a person and a soda can is immense. So I don't understand how it's supposed to be analogous at all to a situation where the lighter top block supposedly destroyed the much heavier bottom block.

 

[Jeffrey Orling]

It's been sop long... Did the designers/engineers ignore a mechanism to stop a runway failure / collapse? Did they expect damage would/could be limited to a local area? It seems unbelievable that they did not consider what would happen if a single floor collapsed for whatever reason. It almost surely would initiate a runaway floor collapse. Slab and connections to axial supports were identical at every floor except for the mech floors. No means to stop a runaway floor collapse were part of the design... that is once a single slab was over loaded and dropped free... it would go runaway. The columns would loose lateral bracing, weaken and buckle. This seems obvious after the fact... but how could they not see it in the "design phase"???

 

[Miss VocalCord]

It's been sop long... Did the designers/engineers ignore a mechanism to stop a runway failure / collapse? Did they expect damage would/could be limited to a local area? It seems unbelievable that they did not consider what would happen if a single floor collapsed for whatever reason. It almost surely would initiate a runaway floor collapse. Slab and connections to axial supports were identical at every floor except for the mech floors. No means to stop a runaway floor collapse were part of the design... that is once a single slab was over loaded and dropped free... it would go runaway. The columns would loose lateral bracing, weaken and buckle. This seems obvious after the fact... but how could they not see it in the "design phase"???

I don't think a single floor collapse would have caused a total collapse of the buildings. However in this collapse a total of 10 to 20 floors including all structures came down.
Also it seems like it was much more a point impact instead of a big flat surface redistributing the forces much more.

 

[econ41]

Also it seems like it was much more a point impact instead of a big flat surface redistributing the forces much more.

You are correct to suggest that it was a concentrated load which started the collapse. Actually the trigger was a linear concentrated impact rather than a single point. As already explained earlier in this thread. And as has been explained on multiple previous occasions.

Here, again, is the graphic - it shows how the still intact wall of perimeter columns (yellow arrow - left of picture) fell through the area of the open office space floor joists. (blue lines) It is the worst case example but the principles were the same for the other three pairs of views - four sides each tower therefor four pairs of opposite sides.

 

[Jeffrey Orling]

I don't think a single floor collapse would have caused a total collapse of the buildings. However in this collapse a total of 10 to 20 floors including all structures came down.
Also it seems like it was much more a point impact instead of a big flat surface redistributing the forces much more.

Typical office floors in the twin towers were all of the same structural capacity and designed for the expected live loads. Design is conservative to some extent and there of course is a "safety factor" in the engineering. But the floors were likely not designed to care multiple floor loads and dynamically applied as well. Engineers find an "economical balance" when the design a floor in a high rise... and they typically look to use less material than more. It looks to me that the structural system was "light weight" aside from the mech floors. There was nothing designed in to arrest a "runaway" collapse of floor slabs or even a section of floor slabs. Once a critical mass presented it would like go right to the ground. Slabs are membrane-like and will distribute loads to some extent... but a large dynamic load could like punch right through and make to the bottom. An issue is how much of a floor structure would be damaged by a localized event? I suppose various damage situations can be computer simulated. Practically I suppose a possibility would be a structure failure on a mech floor involving very heavy "something"... a tank for example... losing supported and dropping... It would be an unstoppable destructive mass. But if a tank would break, the contents disburse and the load no longer concentrated and threatening. Perhaps the only dense and heavy things would be motors or transformers.... which likely would be in core areas.
So where would a large footprint dense object some from to drop through the tower? I suppose a jet engine from a plane strike could be a candidate for that... maybe. It's not very large footprint though.
What scenarios can you envision where the floor slabs lose support?

 

[Jeffrey Orling]

You are correct to suggest that it was a concentrated load which started the collapse. Actually the trigger was a linear concentrated impact rather than a single point. As already explained earlier in this thread. And as has been explained on multiple previous occasions.

Here, again, is the graphic - it shows how the still intact wall of perimeter columns (yellow arrow - left of picture) fell through the area of the open office space floor joists. (blue lines) It is the worst case example but the principles were the same for the other three pairs of views - four sides each tower therefor four pairs of opposite sides.

This is a very clear explanation of how a concentrated (linear) load would destroy the slabs inside the tower.

 

[Thomas B]

they always neglect the most obvious experiment, which would be to just build a miniature tower and show how it can undergo a top-down, smooth collapse when damaged. And I think the reason for this is that such top-down collapses don't really happen in physical experiments.

This is basically my view. There appears to be no way to build a miniature structure that behaves even remotely like the WTC on 9/11. Otherwise, someone would have done it long ago.

Mick's wooden model is held together by the (very weak) floor connections, which is obviously not how buildings actually work.

The word "miniature" here suggests the problem of scale. But a "small" model could actually be built where the floors are 1 or 2 meters and there are only five or six of them. At that scale, it ought to be possible to model the relevant gravity loads. This is also never done.

Newton was able to convincingly model the motion of the moon with a cannonball.

I remain agnostic about what all this means, but, to me at least, one thing is certain: the WTC collapses are hard to explain.

 

[econ41]

.... but, to me at least, one thing is certain: the WTC collapses are hard to explain.

Possibly you have that backwards? I think you mean for you the collapses are hard to understand. You don't need to explain. And a sufficiently qualified person can explain the Twin Towers collapses with little difficulty. To any person high school age or older who seriously wants to learn and can comprehend elements of applied physics.

Explaining the WTC7 collapse to laypersons is harder because the evidence is hidden. The Twin Towers are easier because there is more than sufficient evidence on view in the visual record to explain and prove why the Twins collapsed. The evidence is not in view for WTC7 which is, after all, the primary reason truth movement leaders such as AE911 chose to focus on WTC7.

Explanation is difficult with persons who, for whatever reason, have no wish to learn.

 

[Jeffrey Orling]

I can't remember but.... has there been a discussion / conclusion concerning whether the twin tower design was more, less or as vulnerable as traditional grid/lattice frames to progressive runaway collapse? I don't see a scenario where an entire floor slab collapses at once. I can envision a situation where a local extreme/excessive load will go runaway and plunge through the tower. I can envision a massive floor wide fire critically weakening the truss connections to the structure (as well as the trusses themselves). I don't see why engineers would (over)design for a load situation which would go runaway. Where would this load come from? Would some mechanical equipment be heavy enough to destroy tenant floors? Perhaps water tanks? Having more smaller tanks would be sensible I suppose.

 

[Henkka]

Possibly you have that backwards? I think you mean for you the collapses are hard to understand. You don't need to explain. And a sufficiently qualified person can explain the Twin Towers collapses with little difficulty. To any person high school age or older who seriously wants to learn and can comprehend elements of applied physics.

Explaining the WTC7 collapse to laypersons is harder because the evidence is hidden. The Twin Towers are easier because there is more than sufficient evidence on view in the visual record to explain and prove why the Twins collapsed. The evidence is not in view for WTC7 which is, after all, the primary reason truth movement leaders such as AE911 chose to focus on WTC7.

Explanation is difficult with persons who, for whatever reason, have no wish to learn.

I don't know how you can say it's easy to explain when you have your own personal theory that doesn't entirely align with either NIST or Bazant, which are the mainstream explanations. You'd think if it was easy to explain, everyone would have coalesced around a single theory.

The same applies to WTC 7. In 2020, there was a study published that summarised the various theories about its collapse and concluded that the initiating mechanism is still mysterious, since all the theories disagree:

The collapse of WTC 7 remains to this day a unique event in the history of structural fire engineering. Despite occurring nearly twenty years ago, there is no real way to know what exactly caused its failure.

Despite the tremendous efforts of the various investigative teams, there is no consensus regarding the exact initiating mechanism. Arup’s analysis showed that girder 44-79 would be pulled off of its seat, opposite to the prediction by NIST which show the girders pushed off of their seats. WAI’s analysis points towards a floor beam connection failing followed by entire floor collapsing. Finally, the UoE mechanical room fire scenario predicts that the failure may have occurred due to a completely different fire caused by a breach of the emergency power system.

https://www.researchgate.net/publication/347108749_The_collapse_of_World_Trade_Center_7_revisited

It does however say that there is a "consensus" that fire was the cause. But this is a false consensus, achieved by omitting the University of Alaska study.

But I don't wanna start arguing about WTC 7 or Hulsey in this thread. I'm just making the point that widespread disagreement is not usually a feature of things that are "easy to explain".

 

[econ41]

I can't remember but.... has there been a discussion / conclusion concerning whether the twin tower design was more, less or as vulnerable as traditional grid/lattice frames to progressive runaway collapse?

It has been extensively discussed at the moderate level of sophistication we see on this and similar forums. I've also seen and participated in a couple of other scenarios.

There are a handful of fundamental issues involved
(1) The WTC was designed in a regulatory era when engineering structural design was practiced separately from fire resistance design aspects. That situation is no longer accepted in most countries -I'm unsure of current US practice - USA has a reputation of not keeping up with the leading edge - the old issue priority given to monetary aspects plus a bit of "American Exceptionalism".

The WTC was designed in accordance with the standards of the time. the engineering was innocativer leading edge. the fire resistance not as advanced - simple application of code. The current preferred practice is performance-based integrated design - structure and fire resistance assessed together as a full "system"

The Towers collapsed as a result of gross trauma well beyond the legitimate design envelope. So we don't know and never can know if the Towers would have survived the allowed for design scenario.

So the comparison with ESB and similar conventional concrete structures is on dubious ground if we claim that WTC was "poorly" designed. Yes it had vulnerabilities under gross trauma exceeding design standards. That is NOT a valid basis to conclude WTC design was somehow "wrong". It was a properly designed child of its era. It would not meet other countries' technical standards if proposed to the same design today. I'm not aware of the strict current legal and regulatory status in USA or New York/New Jersey. The new tower was designed and built with WTC collapses evidence and investigation findings taken into account.\

 

[Thomas B]

Possibly you have that backwards? I think you mean for you the collapses are hard to understand.

No I mean explain. If the collapses were *easy* to explain it would be *possible* to replicate them. It's been over 20 years and no model has been built and destroyed in an illuminating way. I conclude that the collapses are hard to explain.

 

[Jeffrey Orling]

We've been over this before.... you can't scale to a desk top model because gravity, and so forth is not "scalable" Imagine making a very small scale models of autos and crashing them... Would you expect the damage to look like the full scale versions? I think not.

 

[Thomas B]

We've been over this before.... you can't scale to a desk top model because gravity, and so forth is not "scalable" Imagine making a very small scale models of autos and crashing them... Would you expect the damage to look like the full scale versions? I think not.

I already dealt with the scale issue. You probably don't need full (3-meter) stories, but, even if you did, a four- or five-story model (made of something much weaker than steel) would do the trick ... IF the collapses were indeed *easy* to explain.

 

[benthamitemetric]

No I mean explain. If the collapses were *easy* to explain it would be *possible* to replicate them. It's been over 20 years and no model has been built and destroyed in an illuminating way. I conclude that the collapses are hard to explain.

This relies on your arbitrary personal requirement that an explanation of an event result in a physical model that reproduces some arbitrary number of characteristics of that event with some arbitrary degree of accuracy. That is not an inherent requirement for an explanation, however.

 

[Thomas B]

This relies on your arbitrary personal requirement that an explanation of an event result in a physical model that reproduces some arbitrary number of characteristics of that event with some arbitrary degree of accuracy. That is not an inherent requirement for an explanation, however.

What's your impersonal, nonarbitrary theory of explanation?

I am happy to grant that I'm saying the collapses are not easy to explain to a standard of explanation that I generally associate with science. (I'm not sure it's just my "personal" view of science. I mean, I'm just requiring replicability here. That's a common -- if perhaps not universal -- requirement.) Many things are easy to explain (to me) using science (i.e., scientific models). The WTC collapses don't seem to be one of them.

 

[econ41]

I don't know how you can say it's easy to explain when you have your own personal theory that doesn't entirely align with either NIST or Bazant,

Please stop the evasive Gish Galloping.

I made a simple assertion of technical fact. Stated simply I said that a suitably competent person - take that as a reference to me - so I can explain the WTC Twin Towers collapses to a person who wants to understand.

Two sides - "I can easily explain" to "someone who wants to understand"

Your posting practices suggest that you don't want to understand and are determined to remain in alleged ignorance.

Just look at the evasions:

that doesn't entirely align with either NIST or Bazant,

We are not discussing either of them

which are the mainstream explanations.

And not the subject of my simple assertion

You'd think if it was easy to explain, everyone would have coalesced around a single theory.

There is no way that I would "think" or expect that highly unlikely outcome.

And your evasions continue - I count a further six in the remainder of your post.

My assertion still stands - I am a 'suitably qualified person' who can easily explain Twin Towers collapses to any honest person who wants to learn. I've done it many times.

 

[econ41]

No I mean explain. If the collapses were *easy* to explain it would be *possible* to replicate them. It's been over 20 years and no model has been built and destroyed in an illuminating way. I conclude that the collapses are hard to explain.

Silly comment. The collapses are easy to explain and have been explained many times to people who want to understand.

I am addressing explanation. Not replication.

 

[Landru]

There is nothing new here. If you want to discuss something new start a new thread.