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Frank Greening Refuted Easily

TruthSeeker1234 said:
This is true of both towers. Greening's notion that the top block remained intact until it hit the bottom is utterly and completely divorced from reality.
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Yes, if he actually believed that the top section stayed intact until it hit the ground, he would be insane.

Can you show me exactly where he says that?
 
TruthSeeker1234 said:
OK. I'll explain. Greening says that the top block of floors fell down through the intact structure below. Stage A.

Then, says Greening, the top block, now sitting on top of the pile of rubble, collapses floor by floor from the bottom up. Stage B.
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You're not reading carefully. He says that it's a "simple model" which he is only using in this section to estimate the total collapse time. He separates the destruction of the lower floors from the upper floors so that he can analyze them separately. When he says we "envision" the collapse in two separate stages for the purposes of this calculation, I don't believe he is implying that he believes they actually happened is two separate stages; I believe he is simply implying that that's a valid way to calculate the total collapse time. If you disagree, you'll need a better reason than just saying it didn't happen in two separate stages.

Clearly, as shown in the gif, the top block begins collapsing from the bottom up.
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Well, no, I don't "clearly" see any such thing. All I see is that you've arbitrarily drawn a red line several floors below where the collapse starts, and then show another frame where the collapse is at that line. How exactly did you determine that the block is collapsing from the bottom up through that cloud of smoke and dust? Anyway, the most reasonable thing to expect is that both are being destroyed more or less equally in the collapse. But again, in the section you quoted, Greening is only trying to estimate the collapse time.

The reason is that he needs the mass to accumulate on the way down in order to continue the collapse. Once you admit the obvious, it becomes clear that the mass is not accumulating, it is disintegrating.
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Baloney! First, he demonstrated why the collapse continued elsewhere -- again, here he's calculating the total time -- and your belief that the "mass is not accumulating, it is disintegrating" is absurd. Except for a small percentage that's being ejected, the falling mass is staying about the same and adding each floor as it falls, whether or not the top block is disintegrating.
 
He says that it's a "simple model" which he is only using in this section to estimate the total collapse time. He separates the destruction of the lower floors from the upper floors so that he can analyze them separately. When he says we "envision" the collapse in two separate stages for the purposes of this calculation, I don't believe he is implying that he believes they actually happened is two separate stages; I believe he is simply implying that that's a valid way to calculate the total collapse time.
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Truthseeker doesn't understand this scientific concept of a "model". That's a sciency word for "useful approximation". Useful in the sense that it makes good predictions, and approximation in the sense that it makes the math easier. We remove some of the complexity of reality in ways that will not effect the quantity we wish to estimate (in this case, the collapse time).

Truthseeker, we understand that when you make a model, you simplify reality. Showing that the model isn't perfect is insufficient to showing the results are incorrect. You need to explain why the simplification from reality to the model effects the quality of the prediction. You've ignored the critical last step.
 
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CurtC said:
Yes, if he actually believed that the top section stayed intact until it hit the ground, he would be insane.

Can you show me exactly where he says that?
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I already did. Here, I'll bold some parts to make it easy for you.

Greening:
We now apply this simple model to the WTC collapse. We assume that both
WTC building collapses began with an upper block of nfloors collapsing onto a series of
lower floors as in the “domino effect”. We shall refer to this process as the first stage of
collapse. For this stage, (see equation 1), we have an initial mass nmf falling onto the
floor below and becoming mass (n+1)mf. This new, enlarged, block of floors descends
with velocity v2= {n/(n+1)}v1through a distance hfat which point itstrikes the floor
below and becomes mass (n+2)mf moving at velocity {n/(n+2)}v2, and so on. This
implies a first stage collapse sequence for WTC 1: all floors from 110 to 96 (= 14 floors)
collapse onto floor 95; all these floors collapse onto 94 93 92 and so on to 32 
1; for WTC 2 all floors from 110 to 81 (= 29 floors) follow the same sequential process.
At the end of each of these collapse events we envision a second stage of collapse
involving the destruction of the upper block of the WTC buildings: for WTC 1 the 97th
floor, plus all floors above, collapse onto the pile of rubble topped by floor 96; this is
followed by floor 98 (plus all floors above) collapsing onto floor 97 and so on. The 2nd
stage sequence for WTC 1 ends with floor 110 collapsing on to all lower floors. For
WTC 2 the 2ndstage involves floor 82 collapsing onto floor 81, followed by 83, 84, etc,
collapsing on to the pile of rubble until floor 110 collapses onto all lower floors.
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You guys can go look at the actual videos of WTC1. What you will discover is that the "collapse" begins like a standard controlled demolition of a 14 story building. It fails at floor 96. 97 and all above come down to 96. Then 98 comes down to 96. Then 99 comes down to 96. Then 100 comes down to 96.

During this time, the stucture below 96 does not move an inch. Only after the upper 14 floors are about half their original height does the next phase begin.

This is exactly the opposite of what Greening imagines.

Greenings language is clear. He means that the top block goes all the way down to the ground. He has to mean that. His theory requires that the mass is accumulating. Utterly divorced from reality.

Here, all three of these videos show it clearly.

http://italy.indymedia.org/uploads/2005/04/wtc1-demolition-1.avi
http://italy.indymedia.org/uploads/2005/04/wtc1-demolition-2.avi
http://italy.indymedia.org/uploads/2005/04/wtc1-demolition-3.avi
 
Anti-sophist said:
Truthseeker doesn't understand this scientific concept of a "model". That's a sciency word for "useful approximation". Useful in the sense that it makes good predictions, and approximation in the sense that it makes the math easier. We remove some of the complexity of reality in ways that will not effect the quantity we wish to estimate (in this case, the collapse time).

Truthseeker, we understand that when you make a model, you simplify reality. Showing that the model isn't perfect is insufficient to showing the results are incorrect. You need to explain why the simplification from reality to the model effects the quality of the prediction. You've ignored the critical last step.
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No, AS, I have explained why Greening's model fails. It fails because it requires accumulating mass, which is at odds with observed reality.
 
TruthSeeker1234 said:
You guys can go look at the actual videos of WTC1. What you will discover is that the "collapse" begins like a standard controlled demolition of a 14 story building. http://italy.indymedia.org/uploads/2005/04/wtc1-demolition-3.avi
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It does?

Please show us your evidence of the use of explosives.

Please show us a CD of a building in which the explosive charges were placed on floors that were fully involved with fire.

Please show us a CD in which the explosives make no sound and leave no seismic signal on monitors in the area.

Please show us a CD of a building that, according to people inside it, showed "obvious signs of movement," making it too dangerous to occupy.

Please show us a CD of a building that, to people outside and to photographs and videos, was bowing inwards at the area that was on fire, indicating imminent collapse.

Do these things, TruthSeeker, and them proceed with your analysis of the rest of the collapse.
 
No, on this thread I think we'll stick to Greening. Simple models are fine. Or not. Depending on the assumptions and the reasoning.

Greening assumes a top block pounding down through the intact building, floor by floor, with mass accumulating. Once the block finally hits bottom, he assumes that the top block collapses bottom up. This may be a valid model for some event somewhere, but clearly it is not a valid model for this event.

His phase 2 happens at the beginning. This invalidates his notion of accumulating mass. The evidence is against him, and he is divorced from reality.

Curt C is showing signs of rationality. Curt, go look at the videos I linked. Report what you see.
 
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TruthSeeker1234 said:
You guys can go look at the actual videos of WTC1. What you will discover is that the "collapse" begins like a standard controlled demolition of a 14 story building.
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You're simply misinterpreting where the collapse starts. As I said, you've got your red line several floors below where the collapse starts.
 
TruthSeeker1234 said:
Simple models are fine. Or not. Depending on the assumptions and the reasoning.

Greening assumes a top block pounding down through the intact building, floor by floor, with mass accumulating. Once the block finally hits bottom, he assumes that the top block collapses bottom up. This may be a valid model for some event somewhere, but clearly it is not a valid model for this event.
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Apparently, you still don't get what this particular "simple model" is intending to do: it's just to estimate the collapse time. Nowhere is this section is Greening using this "simple model" to explain why the tower collapsed! He introduces it by saying, "We now present a simple momentum transfer theory that may be used to calculate values of t_c [collapse time] for each of the WTC towers."
 
Roger_Harris said:
Apparently, you still don't get what this particular "simple model" is intending to do: it's just to estimate the collapse time. Nowhere is this section is Greening using this "simple model" to explain why the tower collapsed! He introduces it by saying, "We now present a simple momentum transfer theory that may be used to calculate values of t_c [collapse time] for each of the WTC towers."
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Roger, are you denying that Greening's model is exactly as I characterize it? Greening has written in plain English, and I've quoted it twice. Yes, he is trying to get at the collapse times, but to get there, he imagines a particular sequence of events. I have shown that the sequence of events is something profoundly different than what he imagines, and it directly impacts his entire model. His model requires the mass to accumulate, floor by floor. He does not allow for mass going outside the footprint. He does not allow for mass becoming pulverized. His model and his hypothesis are directly contradicted by observational data. Data beats imagination.
 
Truthseeker, I also used that animated gif once but it is a little bit a wrong image I have to admit, because that fire at the lower floors is not a point of impact that is somewhere in the middle. But indeed it disintegrates at an early stage, this in fact means that the upper N floors disintegrate when they hit the next N floors, that picture is more a 2N example. But Greening's model indeed requires a block that falls through the building, he should indeed take into account that after a few storeys it disintegrates. A better model would be that the point masses are connected by strings that each can absorb an amount of energy E_i before they break. The only thing that I don't get is that if the initial kinetic energy is about 4 times the energy needed to break a floor it's only assumed to be absorbed by the upper floor of the intact building and so on. If the block has the speed of a plane then this would be the case but for a slow initial velocity the whole frame should still be able to absorb energy, the same for the building of course. This is one of the points I have difficulties with. Energy can be absorbed quickly and transferred through the frame. An other thing to take into account is the mass lost of course.
 
Uuuhhhmmm. OK, how about this:

The top floors collapse in exactly the way he described them in "Stage 2", only now they do it at the top of the building before it all collapses. Assume approximately half of the mass is lost into a huge cloud of debris.

This huge mass is now accelerating at a higher velocity into the top of the remaining building, which begins to collapse in exactly the way he described as "Stage 1". The difference is that it starts falling at a much faster initial speed, because (even though half of the top mass is gone), it is already moving instead of accelerating from zero.

This should result in an even shorter total collapse time.

Thanks for pointing out this (perhaps more realistic) model for calculating collapse time.:rolleyes:
 
You forgot one fine detail Harlequin, at the second stage of collapse the block has an end velocity of over 50m/s, it hits the ground with that speed, if you let it start at the top the speed is zero. I admit the point mass model has more kinetic energy and momentum when it starts at the top than a block falling as a whole.
 
Too busy right now to add much here, but there are a couple of points worth making.

First, if you think you've refuted Greening, then you could always email him and point this out. He's happy to reply to anyone with constructive criticisms.

And second, Frank's sent me his first significant new piece for a while, a 22-page analysis titled "The Pulverization of Concrete in WTC 1 During the Collapse Events of 9-11". I'm not going to summarise it here, but let's just say people whose say nothing more than "there aren't enough big lumps of concretre in these pictures therefore it was controlled demolition" might need to find a new & rather more convincing argument. That should be online by Wednesday/ Thursday.
 
Truthseeker is correct don't any of you know that once something breaks into smaller pieces all of its mass is gone. all of the smaller pieces have no mass or velocity. I believe the missing mass then passes into the ether. or maybe into another dimension.
 
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TruthSeeker1234 said:
I already did. Here, I'll bold some parts to make it easy for you.

Greening:
Click to expand...
We now apply this simple model to the WTC collapse. We assume that both
WTC building collapses began with an upper block of nfloors collapsing onto a series of
lower floors as in the “domino effect”. We shall refer to this process as the first stage of
collapse. For this stage, (see equation 1), we have an initial mass nmf falling onto the
floor below and becoming mass (n+1)mf. This new, enlarged, block of floors descends
with velocity v2= {n/(n+1)}v1through a distance hfat which point itstrikes the floor
below and becomes mass (n+2)mf moving at velocity {n/(n+2)}v2, and so on. This
implies a first stage collapse sequence for WTC 1: all floors from 110 to 96 (= 14 floors)
collapse onto floor 95; all these floors collapse onto 94 93 92 and so on to 32 
1; for WTC 2 all floors from 110 to 81 (= 29 floors) follow the same sequential process.
At the end of each of these collapse events we envision a second stage of collapse
involving the destruction of the upper block of the WTC buildings: for WTC 1 the 97th
floor, plus all floors above, collapse onto the pile of rubble topped by floor 96; this is
followed by floor 98 (plus all floors above) collapsing onto floor 97 and so on. The 2nd
stage sequence for WTC 1 ends with floor 110 collapsing on to all lower floors. For
WTC 2 the 2ndstage involves floor 82 collapsing onto floor 81, followed by 83, 84, etc,
collapsing on to the pile of rubble until floor 110 collapses onto all lower floors.
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hes not envisioning the top crushing the bottom, then the top collapsing, as i pointed out in a previous thread, real life is not turn-based

it seems to me that hes saying the top section crushes a floor below it, then collapses a bit on itself, then crushes the next floor, then itself some more and so on and so forth

i feel this is a bit of an over simplification, as stage 1 and stage 2 would be happening simultaneously, but this is written for the lay person

and before you point out that "this model shoudl only account for the destruction of the top 40-50 floors, the the top is destroyed and gone" let me ask you this, after the top section is crushed, where does the mass go? it certainly isnt gone

thats right, it continues down, continuing to destroy everything below it
 
Originally Posted by CurtC:
Yes, if he actually believed that the top section stayed intact until it hit the ground, he would be insane.

Can you show me exactly where he says that?
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TruthSeeker1234 said:
I already did. Here, I'll bold some parts to make it easy for you.

Greening:
Click to expand...


We now apply this simple model to the WTC collapse. We assume that both WTC building collapses began with an upper block of nfloors collapsing onto a series of lower floors as in the “domino effect”. We shall refer to this process as the first stage of collapse. For this stage, (see equation 1), we have an initial mass nmf falling onto the floor below and becoming mass (n+1)mf. This new, enlarged, block of floors descends with velocity v2= {n/(n+1)}v1through a distance hfat which point itstrikes the floor below and becomes mass (n+2)mf moving at velocity {n/(n+2)}v2, and so on. This implies a first stage collapse sequence for WTC 1: all floors from 110 to 96 (= 14 floors) collapse onto floor 95; all these floors collapse onto 94 93 92 and so on to 32  1; for WTC 2 all floors from 110 to 81 (= 29 floors) follow the same sequential process.

At the end of each of these collapse events we envision a second stage of collapse involving the destruction of the upper block of the WTC buildings: for WTC 1 the 97th floor, plus all floors above, collapse onto the pile of rubble topped by floor 96; this is followed by floor 98 (plus all floors above) collapsing onto floor 97 and so on. The 2nd stage sequence for WTC 1 ends with floor 110 collapsing on to all lower floors. For WTC 2 the 2ndstage involves floor 82 collapsing onto floor 81, followed by 83, 84, etc, collapsing on to the pile of rubble until floor 110 collapses onto all lower floors.
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I've re-bolded this quote for you. Curt was asking for evidence that Greening actually believes his model corresponds to reality. It's quite clear that Greening knows this is a "simple model" that he's "making assumptions" about, that allows him to "envision" a collapse process. No where does he say that this is how it must have happened. Show me anywhere where he unambiguously says that he believes the collapse progressed in this exact manner.
 
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