A Truther writes...

[Bell]

No,Bill has lost the trolling touch.Telltale Tom is at number one at the moment.

Tom is not a troll. Imho.

 

[Dog Town]

Tom is not a troll. Imho.

Right! Parody is the word people are looking for. I know it's hard to tell, parodies of twoof, considering the original content. TT has a great wit.

 

[T.A.M.]

TT is so dry I sometimes forget he is a parody, and lash out at his "stupidity".

TAM

 

[angrysoba]

Thanks very much for the replies, especially for Oystein's point-by-point rebuttal. I think that the two main problems are that 1) I don't know anything about engineering or how the structure could have fallen down and 2) neither does my opponent.

I prefer to ask

a) What would be the point in demolishing the Towers in the first place? It would serve no purpose whatsoever except to tip off structural engineers such as David Ray Griffin that something weird was going on.

b) If they were demolished by controlled demolition there would have been sounds of explosions - there were not - and other phenomenon consistent with explosive force that the Truther says flung steel beams hundreds of feet out laterally. How far, for example, would the glass be flung out?

But the Truther in question is so adamant that they have exposed the "official story" as a lie that they don't feel the need to offer any alternative scenarios.

 

[Oystein]

Thanks very much for the replies, especially for Oystein's point-by-point rebuttal. I think that the two main problems are that 1) I don't know anything about engineering or how the structure could have fallen down and 2) neither does my opponent.

I am not an engineer of any kind, and whatever I write about engineering is basically what I picked up from real engineers (some of them here at JREF), or what I would consider a good measure of common education.

However, the "Truther" you are dealing with purports to base his argument on specifically the "conversation of momentum", a basic physical law. You can argue on that ground without going too much into actual engineering, as all engineering is ultimately subject to physical laws.

I once came up with my own little one-dimensional collapse model, using old-fashioned paper and pencil, and the physics I learned in high school. I made some assumptions about the properties of structural elements that were surely naive and uneducated, but made them such that I was sure to err on the side that would make total collapse less, not more, likely.
My result was, that collapse would progress at an acceleration of about half G, thus a little slower than it did; which is no doubt due to my assumptions being unrealistically conservative.

Here is a rough ouline of my model:

Assumptions:

• I modelled a tower as a stack of 110 columns, each 3.5 meters high.
• Each column (=story) would have a mass of unspecified dimension, with the top column having a mass of 1.
• Each column would have to be able to support the 3 times weight of all columns above it. Accordingly, the mass of columns would increase top to bottom.
• I assumed that a column could support the full 3 times weight of all stories bove it even if compressed or bent, until it is shortened by 10%. At that point, the column would break and offer 0 resistance. "Support the full 3 times weight" means "excert a an upward force 3 times the gravity of the static load".
• Only the column immediately touched by the falling top block would bear the full dynamic load; no wave propagation to stories below
• Collapse initiation would be such a failure event: a story that had already sagged by 10% of its weight breaks and falls freely the remaining 90% of story height.
• g=10 m/s²

Equations needed:

• mass of falling top block above story N: m(N) = sum_n=N+1..110(m_n), where m_n is the mass of the n-th column or story
• Force of gravity: G = m*g
• Upward force of intact columns: A_c = -3*G = -3*m*g
• Deceleration of falling top part by upward force: delta-v = A_c * delta-t
• Conversation of momentum: m(N) * v(N) = (m(N) + m_N) * v(N-1)

What happens story by story is this:
1. The combined weight of stories N+1...110 falls freely a height of 90% of 3.5m = 3.15m and gains speed according to delta-v = g * delta-t
2. The block impacts (collides inelastically with) story N. As the mass of the top section always greately exceeds the mass of the single story below, the downward velocity is reduced by a few percent only
3. The impacted column now excerts an upward force to the falling block; since at the same time, gravity is still pulling downwards, that deceleration has a value of only 2g. Deceleration takes place for a vertical distance of 10% of story height, or 0.35m, which means columns get elastically compressed or bent.
4. If downward velocity reached 0 before the 10% are expended, the fall is arrested. This never happens. Instead, colum will break at this point. Goto 1.

It turns out that v increases by the same amount from story to story. In other words: We have a constant average acceleration downwards. With my assumptions, that average was slighly below 0.5*g. It would decrease if you assume a safety margin greater than 3* static load (a factor of 5 could be equally reasonable), it increases if you assume that columns (or their joints) break sooner than I assumed (in fact, I am sure that I was very generous here).

I prefer to ask

a) What would be the point in demolishing the Towers in the first place? It would serve no purpose whatsoever except to tip off structural engineers such as David Ray Griffin that something weird was going on.

Hey, but think at the sinister laughs that can be had whilst devising such fiendish plans!
I hope you are being sarcastic about Dave the Builder??

b) If they were demolished by controlled demolition there would have been sounds of explosions - there were not - and other phenomenon consistent with explosive force that the Truther says flung steel beams hundreds of feet out laterally. How far, for example, would the glass be flung out?

uhm... if forces and momentum are available to fling large things laterally, the same forces and momentum would be available to fling small pieces, no matter what the source of the force and momentum, not? I am pretty sure that lots of glass and other small pieces were flung out even farther than the steel beams. In fact, lots of lower Manhattan was littered with small things (dust...), only small portions with big things.

But the Truther in question is so adamant that they have exposed the "official story" as a lie that they don't feel the need to offer any alternative scenarios.

JAQing off, aren't they

 

[angrysoba]

uhm... if forces and momentum are available to fling large things laterally, the same forces and momentum would be available to fling small pieces, no matter what the source of the force and momentum, not? I am pretty sure that lots of glass and other small pieces were flung out even farther than the steel beams. In fact, lots of lower Manhattan was littered with small things (dust...), only small portions with big things.

Good point. I think, however, that the glass would have scattered far wider if the columns on every floor had been blown out with explosives given that the forces and momentum would have originated from a different place than the force of a top-down collapse.

I hope you are being sarcastic about Dave the Builder??

Are you saying retired theologians aren't the best authorities on structural engineering?!!??!?!?!??!

Thanks also for the model of the collapse you sketched out as well.

 

[Oystein]

Good point. I think, however, that the glass would have scattered far wider if the columns on every floor had been blown out with explosives given that the forces and momentum would have originated from a different place than the force of a top-down collapse.

Well maybe, but that is merely what you can imagine, and might stand against what others maybe can't imagine

Are you saying retired theologians aren't the best authorities on structural engineering?!!??!?!?!??!

Why yes, they take it directly from God, the Supreme Structural Engineer of the Universe

Thanks also for the model of the collapse you sketched out as well.

My model is pretty bad compared with what's out there. I just wanted to point out that everybody with a basic understanding of mechanics (ETA: the branch of physics) can get down to work with the roughest of assumptions and come up with a basic understanding of the dynamics involved.

In the same vein, I did a very simple experiment:
I took a bundle of drinking straws, cut them to about 10cm to give them a little more strength per cm, put them upright on my table top, and carefully rested my hands on them. Then I removed straw by straw until there wer so few left that they could not support my hand and snapped. Turned out, at least 3 straws were required to statically support my hand.

Then I took 3 times that number: 9 straws. Bundled them. Put them upright. And let my hand freely drop on to them from a height of about 20cm

Turns out, all 9 instantly snap and can't support the now dynamic load of my hand.

Simple experiment, but very instructive to the layman's intuition.

 

[angrysoba]

Thanks again. Also, how about the amount of mass that was lost from it spilling down the sides of the buildings?

I realize that to some extent this shows that the remaining building was resisting far more than thin air (unlike the claim being made) as it obviously wasn't going straight down.

But doesn't this skew the calculations regarding how much downward momentum there was?

 

[Oystein]

Thanks again. Also, how about the amount of mass that was lost from it spilling down the sides of the buildings?

I realize that to some extent this shows that the remaining building was resisting far more than thin air (unlike the claim being made) as it obviously wasn't going straight down.

But doesn't this skew the calculations regarding how much downward momentum there was?

Hmm obviously, as anything that falls outside of the footprint would not impact any intact portions of the building. How much fell outside of the footprint? Hard to guess. Probably less than half of the mass (until it all piled up in a heap on the ground and much spilled sideways from there).
Calculations show that momentum and energy available exceeded maximum design load by a magnitude or more. If you deduct half the mass, you only deduct half the momentum and half the energy, and still remain well above design limits.


More importantly, if your truther is one of the many who argue that the towers fell onto their own footprint and that because of this the case for controlled demolition is strengthened, you need to point out that they can't have it both ways: They can then not claim at the same time that a significant portion of the towers' masses fell outside of the footprint.

 

[angrysoba]

More importantly, if your truther is one of the many who argue that the towers fell onto their own footprint and that because of this the case for controlled demolition is strengthened, you need to point out that they can't have it both ways: They can then not claim at the same time that a significant portion of the towers' masses fell outside of the footprint.

Ah, yes. I did notice that.

Although it isn't so much "a truther" as a whole nest. The thread has been going for months but participation has now thinned out.

http://www.craigmurray.org.uk/archives/2010/01/the_911_post.html

 

[The Big Dog]

Ah, yes. I did notice that.

Although it isn't so much "a truther" as a whole nest. The thread has been going for months but participation has now thinned out.

http://www.craigmurray.org.uk/archives/2010/01/the_911_post.html

Angrysoba, I had missed the fact that you were one of the truthers in that truther nest.

Ah.

Did you take the time to review the verinage video I linked above? According to your truther friend, that should not have worked. You will also note that a substantial portion of the structure (the facade) "spilled down the side of the building."

 

[angrysoba]

Angrysoba, I had missed the fact that you were one of the truthers in that truther nest.

Ah.

Did you take the time to review the verinage video I linked above? According to your truther friend, that should not have worked. You will also note that a substantial portion of the structure (the facade) "spilled down the side of the building."

Truther? No, not me. As you would be able to see if you read any of my comments there.

I have seen the verinage demolitions before and in fact posted videos of them over there. Of course there was plenty of wailing and gnashing of teeth and insistence that it didn't apply to the Twin Towers collapses for various reasons. Regarding the conservation of momentum they argued that in the verinage demolitions there was a considerable visible slowdown in each whereas there wasn't for the towers.

They're just too fond of their little world of denial.

 

[CORed]

I think he forgot there already is a force acting on the floors all the time. It's called gravity.

Truthers seelm to have a lot of difficulty with advanced physics concepts like gravity and thermal expansion.

 

[CORed]

As Frank Verismo points out, a great deal of the mass was pulverised in any case, so the full weight of the above sections were dispersed each time a new floor was reached by the downward progression.

Yes, when you break something into pieces, its mass disappears. That's why avalanches and rockslides never snap large tree trunks or knock down buildings.

If you want to use physics to try to debunk the "official story", it helps if you're not completely ignorant of physics.

 

[bill smith]

Thanks again. Also, how about the amount of mass that was lost from it spilling down the sides of the buildings?

I realize that to some extent this shows that the remaining building was resisting far more than thin air (unlike the claim being made) as it obviously wasn't going straight down.

But doesn't this skew the calculations regarding how much downward momentum there was?

Here's another model

'' Take 240 long spaghetti sticks to act as as the perimeter columns with an aditional 47 x 6-stick bundles to represent the stronger core columns spaced in a rectangle to cover about 60% of the centre of the structure. Then you have 110 x compressed glue and superfine sugar floors made to scale with holes drilled to correspond to the column locations. Then each floor is carefully slid down over he spaghetti columns and glued into position corresponding to the 110 floors of the WTC Towers. Allow to dry. Then anchor the column bases in a solid surface. Allow to dry.

Finally, lift up the top (and lightest) 10% (C) of the model and drop it say 12'' onto the lower 90% (A).

Will the top 10% (C) crush the lower 90% (A) right down flat on the ground ?

That is what happened at the WTC on 9/11 for the first time on the recorded history of the Planet Earth and not only once but twice in an hour.

 

[angrysoba]

Here's another model

'' Take 240 long spaghetti sticks to act as as the perimeter columns with an aditional 47 x 6-stick bundles to represent the stronger core spaced in a rectangle to cover about 60% of the centre of the structure. Then you have 110 x compressed glue and superfine sugar floors made to scale with holes drilled to correspond to the column locations. Then each floor is carefully slid down over he spaghetti columns and glued into position corresponding to the 110 floors of the WTC Towers. Allow to dry. Then anchor the column bases in a solid surface. Allow to dry.

Finally, lift up the top (and lightest) 10% (C) of the model and drop it say 12'' onto the lower 90% (A).

Will the top 10% (C) crush the lower 90% (A) right down flat on the ground ?

That is what happened at the WTC on 9/11 for the first time on the recorded history of the Planet Earth and not only once but twice in an hour.

This one's better Bill:

Some Truthers I know are incensed when that picture is shown, "OoooOOoooh! You're making Gage look stupid!" They howl!

No, Gage makes Gage look stupid. And he keeps doing it.

 

[bill smith]

Here's another model

'' Take 240 long spaghetti sticks to act as as the perimeter columns with an aditional 47 x 6-stick bundles to represent the stronger core columns spaced in a rectangle to cover about 60% of the centre of the structure. Then you have 110 x compressed glue and superfine sugar floors made to scale with holes drilled to correspond to the column locations. Then each floor is carefully slid down over he spaghetti columns and glued into position corresponding to the 110 floors of the WTC Towers. Allow to dry. Then anchor the column bases in a solid surface. Allow to dry.

Finally, lift up the top (and lightest) 10% (C) of the model and drop it say 12'' onto the lower 90% (A).

Will the top 10% (C) crush the lower 90% (A) right down flat on the ground ?

That is what happened at the WTC on 9/11 for the first time on the recorded history of the Planet Earth and not only once but twice in an hour.

It seems crazy to contemplate that the top 10% of anything, large or small can crush the lower and stronger-built 90% of the same structure down to the ground by gravity alone. There is however a very good reason for thinking that. Because it IS totally cazy to contemplate ..

 

[The Big Dog]

Truther? No, not me. As you would be able to see if you read any of my comments there.

I have seen the verinage demolitions before and in fact posted videos of them over there. Of course there was plenty of wailing and gnashing of teeth and insistence that it didn't apply to the Twin Towers collapses for various reasons. Regarding the conservation of momentum they argued that in the verinage demolitions there was a considerable visible slowdown in each whereas there wasn't for the towers.

They're just too fond of their little world of denial.

Am I reading that web site wrong?

"Posted by: angrysoba at January 28, 2010 7:36 AM
No matter whether the buildings were properly constructed or not, the undisputed facts are that all three buildings collapsed in freefall time. Unless Newtonian physics were suspended in NY on 9/11, that implies that all of the potential energy the buildings possessed by virtue of their height had to be converted to kinetic energy to make it to the ground in the time they did. No further energy would be left to collapse the building and break the joints. It is impossible for the buildins to have collapsed of their own accord, particularly as the path was that of the greatest resistance."

Wow, that site is insanely misleading, I can't tell whether you wrote that or not.

But no matter, tell your friends that whether or not the "slowdown" in the towers was "visible" the fact is that the collapse was not in free fall or even close.

It is a damn good thing that physics is not limited to what is visible to the naked eye on crappy you tube videos.

 

[DGM]

It seems crazy to contemplate that the top 10% of anything, large or small can crush the lower and stronger-built 90% of the same structure down to the ground by gravity alone. There is however a very good reason for thinking that. Because it IS totally cazy to contemplate ..

The problem is the top 10% did not crush the bottom 90%. This is propaganda promoted by the "truth" movement. The top 10% crushed 1% of the bottom 100%. Do you know what the difference is? After that the 1% is added to the top 10% so it can work on the next 1% of the bottom 100%. (numbers simplified)

 

[bill smith]

The problem is the top 10% did not crush the bottom 90%. This is propaganda promoted by the "truth" movement. The top 10% crushed 1% of the bottom 100%. Do you know what the difference is? After that the 1% is added to the top 10% so it can work on the next 1% of the bottom 100%. (numbers simplified)

If 10% of an item can crush the lower and stronger 90% of the same structure by gravity alone then you will surely be able to show the readers other examples of this happening. Choose any example from the recorded history of this planet