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stundie
QUOTE
No Stundie,

We ALL agree there were EXPLOSIVE sounds that day.

Glad we can agree on something??

QUOTE (->
 QUOTE No Stundie,We ALL agree there were EXPLOSIVE sounds that day.

Glad we can agree on something??

But most of us realize that the impacts of jets at 400 to 500 mph and the collapse of two 110 story buildings is going to generate explosive sounds.

This is hilarious!!

So what do "most" of you think caused the explosions after the impacts?
So what do "most" of you think caused the explosions after the collapses?
So what do "most" of you think caused the explosions heard at the WTC 7??

You have given us a plane wing theory, which doesn't add up. Now you are supporting a "any materials failing" could cause an explosive sound theory, which still doesn't add up.

If it did, then you should be able to demonstrate this in another building collapse, where other components of a building fail and cause an explosive sound?

I'll await your evidence?? Which I know doesn't exsist??

QUOTE
And most of us realize that a huge building left on fire for hours is likely to generate some explosive sounds on its way to collapsing.

Then you should be able to explain what the explosive sounds are then?

So why haven't you??

QUOTE (->
 QUOTE And most of us realize that a huge building left on fire for hours is likely to generate some explosive sounds on its way to collapsing.

Then you should be able to explain what the explosive sounds are then?

So why haven't you??

And most of us realize, that in that burning heap of buildings, along with hundreds of vehicles, chemicals, gas lines etc that there would be residual explosions (note, most all High Explosives WON'T detonate from heat, they JUST burn)

So again, you are showing things which can explode, but you are providing no evidence any of these exploded at WTC. You just assume it?? Your opinion hey??

QUOTE
So, you need OTHER EVIDENCE to support the existence of Explosive Demolition.

There is other evidence. Rodriguez says he saw an explosion, look at the footage of the WTC, you will see little explosions going off before the collapse, Prof Jones analysis as found traces of Nitrates...Maybe you should read his paper, unless you have him down as a kook??

There is plenty of evidence, which supports the explosive hypothesis than any of your plane wings/any material failing causes explosives.

QUOTE (->
 QUOTE So, you need OTHER EVIDENCE to support the existence of Explosive Demolition.

There is other evidence. Rodriguez says he saw an explosion, look at the footage of the WTC, you will see little explosions going off before the collapse, Prof Jones analysis as found traces of Nitrates...Maybe you should read his paper, unless you have him down as a kook??

There is plenty of evidence, which supports the explosive hypothesis than any of your plane wings/any material failing causes explosives.

So far you have provided NONE.

The funny things, is you have provided poor explanations which do not fit the evidence??

QUOTE
The point about the Seismometer is the impact of the plane was MORE ENERGETIC than the 93 explosion.

And when did I ever argue that the impact of the planes was less energetic than the 93 explosion?

You make these arguments up that I have NEVER MADE. You are becoming a strawman specialist?

QUOTE (->
 QUOTE The point about the Seismometer is the impact of the plane was MORE ENERGETIC than the 93 explosion.

And when did I ever argue that the impact of the planes was less energetic than the 93 explosion?

You make these arguments up that I have NEVER MADE. You are becoming a strawman specialist?

Why did Rod hear the impact "appear" to come from the below him?
IMO Explosives weakening the foundation of the WTC....What do you think it was?? A coke machine? The plane wing fell to the basement and failed theory?

QUOTE
Simple, the speed of sound is much faster in steel than in the air.

So this explosive sound traveled through the steel and made Rodriguez think it appear from below?? hahahaha!! Is this what you are suggesting?

I'll await your evidence, that this is possible and why this strange phenomenon has never been reported before.

QUOTE (->
 QUOTE Simple, the speed of sound is much faster in steel than in the air.

So this explosive sound traveled through the steel and made Rodriguez think it appear from below?? hahahaha!! Is this what you are suggesting?

I'll await your evidence, that this is possible and why this strange phenomenon has never been reported before.

And YES the evidence DOES support a fireball generated from the aircraft impact affecting the basement/lobby levels of WTC 1 based on all the many BURNT victims on those floors (including the maint guy who got burnt based on a FIRE coming out of an elevator in the basement levels).

Please provide a path of the fireball through the WTC? You could also explain how the fireball appeared to affect no other floors? How it managed to damage the lobby, but it didn't appear to damage any other floor.

You could also explain how it didn't ignite until it reached the lobby causing the explosion? I'll await your so called science??
QUOTE
Burnt victims would NOT be expected from the detonation of HIGH EXPLOSIVES however.

A completely false statement, because it would depend on the explosive used...
QUOTE (->
 QUOTE Burnt victims would NOT be expected from the detonation of HIGH EXPLOSIVES however.

A completely false statement, because it would depend on the explosive used...
Oh yeah?

Where and When and by Who?
Gordon Ross to name one of a few.
QUOTE
The fact is Stundie, you keep bringing up things which have been REPEATEDLY shown to be FALSE.

Like what?
QUOTE (->
 QUOTE The fact is Stundie, you keep bringing up things which have been REPEATEDLY shown to be FALSE.

Like what?
Which is one reason most of the regulars don't even bother with you.

Arthur
Most of the others appear to be more interested in the physics of the planes impacting the WTC. I cannot add to it because I do not have the expertise.

If others want to ignore me, that's fine. I have no issue with it and maybe they have no issues with what I am saying! Maybe they do not care for what I am saying. However, even though your posts are direct to me, you IGNORE my points, because as you know answering them may require you to change your beliefs.
Nope Stundie,

As the evidence shows, including your own "sound engineer" source, there were no explosions prior to the collapse.

Rod felt it from below prior to from above PRECISELY because sound travels MUCH faster in steel than in air. Its a WELL KNOWN scientific principle.

There were fires on more floors than the basement and lobbies. Read the reports, the fires erupted FROM THE ELEVATOR shafts, which DID include shafts that ran from the impact floor as ONE CONTINUOUS SHAFT to the basement.

Yes, there are explosives that can cause burning, but there AREN'T explosives that can both damage the MASSIVE basement structure of the WTC and cause burning.

I've explained the likely sources of explosive sounds.

The fact is NO EVIDENCE that EXPLOSIVES went off (i.e Metal damaged in the UNIQUE manner that is consistant with the use of HE) has ever been shown.

As far as the basement of the WTC, dozens of pictures taken during the last stages of the clean up show a fairly pristine condition to the basement structure. The fact is the collapse stopped WELL above the basement (over 100 feet above bedrock) and didn't damage the massive bottom columns. The fact is, the collapse began NOT at the basement but at the impact floors. The fact is the collapse began by a SLOW pull in of the exterior columns ON THE FIRE and IMPACT floors, which is CONSISTANT with a fire induced collapse and is NOT CONSISTANT with an explosive induced collapse.

Oh, and that point about Gordon Ross, that's HILARIOUS.

Arthur
wcelliott
Al K. - Quit acting like you're interested in the truth, you aren't, and that's obvious.

Also, if you don't understand something, that doesn't make it a lie, that just means you're stupid.

The N-shaped waveform that Trippy provided showed a vertical leading edge, that sample is from the direct-path from the explosive. It would look like it had a slope less than 90degrees if it had been sampled at, say, 1million samples per second.

The decreasing slope following is from the reflections of that very-short undersampled impulse reflecting off the environment nearby. The speed of sound is ~1100ft/second, so the parts of the waveform coming in the first millisecond or so comes from paths that had about an additional foot more than the most-direct path. The blast within a foot of the original detonation was still almost as great as the original blast, so the amplitude of the signal 1ms after the initial spike is slightly smaller than the peak. Likewise, the same effect applies to the signal at peak+2ms, it took a path that was about 2 feet longer than the direct path, and there's a lot more area reflecting at that additional range, and the amplitude is smaller yet, and so you keep getting a downward slope, and that's where that "N-shape" comes from, when you have an explosion IN AN ENVIRONMENT, the INITIAL SAMPLE IS DUE TO THE DETONATION, AND EVERYTHING THAT FOLLOWS IS REFLECTION OFF THE ENVIRONMENT, WHICH MAKES IT *ARTIFACT*, NOT CHARACTERISTIC TO THE DETONATION ITSELF!!!

How dense are you!?! I've explained this a dozen times!

Stundie, I don't have time to raise your level of education, I'm late for work. Just re-read what I've written and try to understand it instead of just arguing from your position of Political Superiority/Total Ignorance.
QUOTE (Al Khwarizmi - step-by-step+Oct 22 2007, 02:16 AM)
Arthur:
==================
Can you logically explain how you think the thermate ends up in the very corner the plane just happened to end up in?
Heck of a coincidence don't you think?

==================
I already answered that question of logistics---not physics---when it was thrown at me by someone without common sense several hundred desultory pages ago. I refuse to play that game.

Really? Or do you just prefer to duck the question because I went back over a year reading your posts and found nothing of the sort.

Arthur
QUOTE (Al Khwarizmi - step-by-step+Oct 22 2007, 02:37 AM)
Arthur:
==========
Finally, what you IGNORE is that descriptions of EXPLOSIONS are not the same as EVIDENCE of EXPLOSIVES.
==========
If it ejects dust jets and debris horizontally at an extremely high velocity, it walks like a duck.
If it produces a crash-boom-rumble that sounds like an explosion, it quacks like a duck.
If it produces a blast that knocks people off their feet, it probably is a duck.

What you IGNORE is that evidence of EXPLOSIVES is the same as EVIDENCE of EXPLOSIVES.

What would constitute evidence for use of explosives in your mind?
==================

EXCEPT,

The dust jets were LOCALIZED, as in one window.

A High Explosive, powerful enough to cut one of the structural columns would NOT be LOCALIZED and produce a high speed jet out of just ONE window.

We also know that a series of pre-planted HE charges powerful enough to collapse the tower would have to inflict more damage to more columns than the planes did.

That clearly didn't happen.

We also know that there was no practical or logical way to INSTALL HE in the building sufficient to bring it down.

CT'ers always skip this point.

We've been over the SOUND issue, clearly one can create LOUD SOUNDS with very fast attack rates that RESEMBLE those generated by HE without resorting to actually using HE.

But what IS clear is there were NOTHING that would be thought of as high explosive sounds immediately PRECEEDING the collapse of EITHER tower.

Nor is there any EXPLOSIVE explanation for the slow pull in of one wall of each tower.

We've already been over the quantity of air in the tower and how its collapse would generate air blasts that WOULD knock people off their feet. Unlike a HE SHOCKWAVE which would more likely KILL.

Evidence, would be a significant quantity of structural steel with damage consistant with demolition by HE.

According to NIST, their engineers going over the scrap heap found none.

Arthur

QUOTE (wcelliott+Oct 22 2007, 10:36 AM)
Al K. - Quit acting like you're interested in the truth, you aren't, and that's obvious.

Al's only purpose here is to try to deflect blame from the 19 Arab Fundamentalists that carried out the attack and the Al Qaeda leaders behind it.

Pretty pathetic actually.

See: http://forum.physorg.com/index.php?showtop...indpost&p=98658

Arthur
Trippy
QUOTE (NEU-FONZE+Oct 23 2007, 02:01 AM)
Trippy:

Thermite/thermate does NOT produce yellow smoke because of the presence of sulfur!

First of all, sulfur additions to thermite to make thermate are around 2% by weight. That makes sulfur a MINOR ingredient.

Upon ignition, the sulfur in thermate will burn/oxidize to SO2 which is colorless.

The smoke from thermite/thermate is mostly white Al2O3.

If any redish/orange/yellow smoke IS produced when thermite is used to cut steel this is from the iron oxides present in the thermite reaction.

I suspect the iron-worker in the photo you posted is using a thermal (oxygen) lance, not thermite/thermate!

1. You're assuming that the Sulfur undergoes complete combustion.
2. I suggest you email the people in charge of 'debunking 911' and tell them they are wrong about the yellow smoke and yellow residue.
3. I suggest while you're at it you tell them they're wrong about the tool being used by the iron cutter, even though I imagine they sourced their information from the same place the sourced the image.
frater plecticus
QUOTE (adoucette+Oct 22 2007, 05:05 PM)
Al's only purpose here is to try to deflect blame from the 19 Arab Fundamentalists that carried out the attack and the Al Qaeda leaders behind it.

Pretty pathetic actually.

See: http://forum.physorg.com/index.php?showtop...indpost&p=98658

Arthur

1) how do we know the hijackers were arabs?

2) how do we know that the hijackers were fundamentalists?

3) how do we know the hijackers were responsible for 9-11?

4) how do we we know that Al-qaeda were the "team" behind the hijackers?

Arthur
frater plecticus
QUOTE (adoucette+Oct 22 2007, 06:42 PM)

Arthur

From beyond the grave? Pretty impressive Arthur.
Not when you video-tape yourself PRIOR to the hijacking.

Arthur
NEU-FONZE
Trippy:

So your "reference" is a debunking site!

Do you believe everything you read on the internet?

Here's my reference:

Comprehensive Inorganic Chemistry by R. C. Brasted

Volume 8 page 123:

"When sulfur is heated in air to approximately 360 deg C, combustion takes place with the formation of sulfur dioxide...."

Also on page 28 of the same volume there is a section on the properties of sulfur vapor. Here we read that sulfur vapor in the temperature range 300 - 940 deg C is usually studied in inert atmospheres such as N2 "to prevent SO2 formation."
The whole issue is nothing but a CT'er RED HERRING.

We know that a significant amount of the plane and misc office material was burning in that corner of the building for the duration and there was a large supply of UPS batteries in the floor above (also on fire).

We do know that there were O2 generators on the plane and other metal alloys, besides Aluminum that could burn.

The fact that there was a metal fire and a glowing material flowed out of the corner of the tower is a piss poor excuse for postulating that the cause was pre-planted thermite.

Arthur
frater plecticus
QUOTE (adoucette+Oct 22 2007, 07:00 PM)
Not when you video-tape yourself PRIOR to the hijacking.

Arthur

>>>to be found 5 years later...
stundie
QUOTE
Nope Stundie,

As the evidence shows, including your own "sound engineer" source, there were no explosions prior to the collapse.

Are you genuinely this stupid??

Why do you think this sound engineer as no explosions prior to the collapse??

I'll give you a clue, could it be that he is analyzing the footage of the collapse?? and nothing before it.

QUOTE (->
 QUOTE Nope Stundie,As the evidence shows, including your own "sound engineer" source, there were no explosions prior to the collapse.

Are you genuinely this stupid??

Why do you think this sound engineer as no explosions prior to the collapse??

I'll give you a clue, could it be that he is analyzing the footage of the collapse?? and nothing before it.

Rod felt it from below prior to from above PRECISELY because sound travels MUCH faster in steel than in air. Its a WELL KNOWN scientific principle.

So what you are suggesting Arthur because sound travels through steel much quicker than air means that when an explosions in a steel building goes off above, it appears to come from below??

HAHAHAHAHAHAHAHAHA!!! OH MY GOD!!The worse part is, I think you are serious!! HAHAHAHAHA!! What kind of bunk physics are you suggesting here??

This is right up there with your plane wing theory causes explosions!! hahahahaha!!

QUOTE
There were fires on more floors than the basement and lobbies.

Fires in the lobby?? hahahahaha!! Have you seen the Naudet film?? Firefighters are not tackling a blaze in the lobby??

QUOTE (->
 QUOTE There were fires on more floors than the basement and lobbies.

Fires in the lobby?? hahahahaha!! Have you seen the Naudet film?? Firefighters are not tackling a blaze in the lobby??

Read the reports, the fires erupted FROM THE ELEVATOR shafts, which DID include shafts that ran from the impact floor as ONE CONTINUOUS SHAFT to the basement.

Please show us the path of your magic fireball and explain how it damaged the lobby and basement, yet it didn't damage any other floors between!!

This will be hilarious, but I suspect you will ignore it too hold onto your OBL theory. lol

QUOTE
Yes, there are explosives that can cause burning, but there AREN'T explosives that can both damage the MASSIVE basement structure of the WTC and cause burning.
Gotcha...You are a walking talking contradiction!!

So a fireball from Kerosene can cause the damage, but an explosive device which burns can't?? hahahahahahahahaha!!You are just too funny Arthur!!

Plus, you have changed position from explosive cannot cause burning, to yes they can cause burning, but can't cause the damage in the basement of WTC?? Yet kerosene based fireballs can?? hahahahahahahaha!!

You are providing me with many a laughs here with your ignorance and your creation of facts/evidence to support your claims. Even when they are so wrong!!

QUOTE (->
 QUOTE Yes, there are explosives that can cause burning, but there AREN'T explosives that can both damage the MASSIVE basement structure of the WTC and cause burning.
Gotcha...You are a walking talking contradiction!!

So a fireball from Kerosene can cause the damage, but an explosive device which burns can't?? hahahahahahahahaha!!You are just too funny Arthur!!

Plus, you have changed position from explosive cannot cause burning, to yes they can cause burning, but can't cause the damage in the basement of WTC?? Yet kerosene based fireballs can?? hahahahahahahaha!!

You are providing me with many a laughs here with your ignorance and your creation of facts/evidence to support your claims. Even when they are so wrong!!

I've explained the likely sources of explosive sounds.

But your likely sources are not verified, provable or indeed bear any relation to reality. You just say it could be anything other than explosives, which still doesn't rule out the possibility of explosives!

QUOTE
The fact is NO EVIDENCE that EXPLOSIVES went off (i.e Metal damaged in the UNIQUE manner that is consistent with the use of HE) has ever been shown.

Yes there is, again read Prof Jones about the nitrates, look at the videos of WTC collapse, plus there is a picture of a beam which looks suspiciously like it's cut with explosives. Some debunkers reckon that it was cut with a torch, which begs the question, why cut a beam with a torch at an angle, when it takes longer to cut?

QUOTE (->
 QUOTE The fact is NO EVIDENCE that EXPLOSIVES went off (i.e Metal damaged in the UNIQUE manner that is consistent with the use of HE) has ever been shown.

Yes there is, again read Prof Jones about the nitrates, look at the videos of WTC collapse, plus there is a picture of a beam which looks suspiciously like it's cut with explosives. Some debunkers reckon that it was cut with a torch, which begs the question, why cut a beam with a torch at an angle, when it takes longer to cut?

As far as the basement of the WTC, dozens of pictures taken during the last stages of the clean up show a fairly pristine condition to the basement structure.The fact is the collapse stopped WELL above the basement (over 100 feet above bedrock) and didn't damage the massive bottom columns.

Oh please...Stop lying to yourself Arthur, because you are only fooling yourself.

And as for the foundations...well from what I remember, there was nothing left of those either.

QUOTE
The fact is, the collapse began NOT at the basement but at the impact floors.

Ah....More strawmen!
QUOTE (->
 QUOTE The fact is, the collapse began NOT at the basement but at the impact floors.

Ah....More strawmen!
The fact is the collapse began by a SLOW pull in of the exterior columns ON THE FIRE and IMPACT floors, which is CONSISTENT with a fire induced collapse and is NOT CONSISTENT with  an explosive induced collapse.

So you know what a "fire induced collapse" is? Even though there as never been any reported fire induced collapses of large building before or after 9/11??

You just make this up as you go along don't you Arthur!! hahahahaha!!

QUOTE
Oh, and that point about Gordon Ross, that's HILARIOUS.

Arthur

Oh...Sorry have you a rebuttal of Gordon Ross paper on the WTC??

Oh and please do not even think of quoting Newtons Bit from over at the SLC and JREF forum. I've embarrassed him and Metamars (I believe he is a member here too!) points out whats wrong with Newtons rebutal.
Trippy
QUOTE (NEU-FONZE+Oct 23 2007, 08:02 AM)
Trippy:

So your "reference" is a debunking site!

Do you believe everything you read on the internet?

Here's my reference:

Comprehensive Inorganic Chemistry by R. C. Brasted

Volume 8 page 123:

"When sulfur is heated in air to approximately 360 deg C, combustion takes place with the formation of sulfur dioxide...."

Also on page 28 of the same volume there is a section on the properties of sulfur vapor. Here we read that sulfur vapor in the temperature range 300 - 940 deg C is usually studied in inert atmospheres such as N2 "to prevent SO2 formation."

I'm well aware of the chemical properties of Sulfur, having also passed first year chemistry. I was simply conveying the information that I did manage to find, in response to a direct question by Al-K, and then providing a seemingly logical reason why that might be expected to be the case.

The point that you're seemingly missing in all of this, is that like in the case of the formation of soot, a requirement for the yellow smoke to form would neccessarily have to be that the sulfur vapour has to cool enough to be able to condense before it can completely react with the air.

Now, as I'm sure you're aware heating sulfur under an open atmosphere is a sigfnificantly different situation from doing so as part of a thermate charge.

If you have a relevant source that axdresses thermate charges directly, feel free to cite it, otherwise feel free to email the iron cutters and tell them that they're wrong.
einsteen
QUOTE (NEU-FONZE+Oct 22 2007, 01:22 AM)
Einsteen:

What is the energy needed to crush an F4 vs a Boeing 767?

Well, according to Wierzbicki, the force to crush an aluminum cylinder with a diameter and wall thickness the size of a Boeing 767 is 15.5 MN. Multiplying by 48.5, the length of the aircraft in meters, we have 752 MJ. Thus the energy to crush a Boeing 767 traveling at 240 m/s is about 21 % of the impact energy.

For an F4 jet, the aircraft's length is 18 meters and we have to remember that the crushing force varies as the square root of the diameter of the fuselage. Since the F4 is about 1/2 the diameter of a Boeing 767 this gives an additional factor of sqrt of 2. From this type of information I estimate the energy to crush the F4 is ~ 197 MJ. The impact KE of the F4 in the Sandia test was 439 MJ, hence the energy to crush an F4 traveling at 215 m/s is about 45 % of the impact energy.

Thanks a lot, but for the F4 jet the (near)linear behavior almost implies that it is a couple of orders lower, btw is the Sugano paper also readable online ? I think the linear line that OneWhiteEye created is a great piece of work that should be taken seriously. On the other hand it is unthinkable that such a big expensive project with a plane and accelerometers gives a wrong result, or am I wrong ? But that doesn't explain the difference and Greg Jenkins also came with the linear line. Is Sugano around somewhere ? Maybe he/she could comment.

The square root of the diameter of the fuselage... it's a little bit counterintuitive, if you think in terms of the amount of material used and the energy needed, but that has of course to do with things like slenderness and the fact that a cylinder shell is of course stronger than an other shape.
Grasshopper

Are you saying that at the moment of collapse there was no "explosive sound?" (according to the evidence presented in this thread-EDIT: what I mean is, at the moment right before collapse) This seems to be what you're saying, and if so it would explain the apparent miscomunication going on with stundie.

Just wanted to know, as I often follow this debate here.

(naturally, it could be ME who is misunderstanding...)
wcelliott
Stundie -

From Wikipedia - "Thus in steel the speed of sound is approximately 5100 m·s-1."
The speed of sound in air is about 340m/s.

Thus, in the WTC towers, a mechanical failure of steel under load happening 1000feet up in the air will be coupled to the structural steel and be transmitted down the structure at a rate of 5,100m/s, while the sound propagating through the air of the same event would be travelling the same 1000 feet at 340m/s, so the shock wave through the steel arrives in 0.06seconds, while the sound through the air arrives in 0.90 seconds.

HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA!!!!
QUOTE (stundie+Oct 22 2007, 03:26 PM)

Fires in the lobby?? hahahahaha!! Have you seen the Naudet film?? Firefighters are not tackling a blaze in the lobby??

Please show us the path of your magic fireball and explain how it damaged the lobby and basement, yet it didn't damage any other floors between!!

This will be hilarious, but I suspect you will ignore it too hold onto your OBL theory. lol

From various news services:

http://www.firehouse.com/terrorist/911/mag.../gz/blaich.html

We proceeded into the north tower ...

We started going up the B stairway. As we got to the third floor of the B stairway, we forced open an elevator door which was burnt on all three sides. The only thing that was remaining was the hoistway door. And inside the elevator were about ? I didn?t recognize them initially, but a guy from 1 Truck said oh my God, those are people. They were pretty incinerated. And I remember the overpowering smell of kerosene. That?s when Lieutenant Foti said oh, that?s the jet fuel. I remember it smelled like if you?re camping and you drop a kerosene lamp.

The same thing happened to the elevators in the main lobby. They were basically blown out. I don?t recall if I actually saw people in there.

What got me initially in the lobby was that as soon as we went in, all the windows were blown out, and there were one or two burning cars outside. And there were burn victims on the street there, walking around. We walked through this giant blown-out window into the lobby.

There was a lady there screaming that she didn?t know how she got burnt. She was just in the lobby and then next thing she knew she was on fire. She was burnt bad. And somebody came over with a fire extinguisher and was putting water on her.

That?s the first thing that got me. That and in front of one of the big elevator banks in the lobby was a desk and I definitely made out one of the corpses to be a security guard because he had a security label on his jacket. I?m assuming that maybe he was at a table still in a chair and almost completely incinerated, charred all over his body, definitely dead. And you could make out like a security tag on his jacket. And I remember seeing the table was melted, but he was still fused in the chair and that elevator bank was melted, so I imagine the jet fuel must have blown right down the elevator shaft and I guess caught the security guard at a table, I guess at some type of checkpoint.

http://www.pbs.org/newshour/bb/terrorism/j...very_10-11.html

Mututanont ... was just arriving for work and in the lobby when the first of the Trade Centers' two towers was hit.

MUTUTANONT, Burn Victim: Everybody heard the explosion you know,, "boom, boom," something like that, and then we kind of stopped and said, "what?"

DENTZER: Mututanont ran out of the building then fell after flying glass sliced through a tendon in her leg. A wall of fire followed her outside.

MUTUTANONT: Swept to my back from my feet up and then I see fire all over, in my hair, also. A lot of people just blew away, you know, like that.

DENTZER: ... Mututanont ... was one of 25 seriously burned patients who eventually ended up at the Burn Center here at New York Presbyterian Weill Cornell Medical Center.

stundie
QUOTE (wcelliott+Oct 22 2007, 07:50 PM)
Stundie -

From Wikipedia - "Thus in steel the speed of sound is approximately 5100 m·s-1."
The speed of sound in air is about 340m/s.

Thus, in the WTC towers, a mechanical failure of steel under load happening 1000feet up in the air will be coupled to the structural steel and be transmitted down the structure at a rate of 5,100m/s, while the sound propagating through the air of the same event would be travelling the same 1000 feet at 340m/s, so the shock wave through the steel arrives in 0.06seconds, while the sound through the air arrives in 0.90 seconds.

HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA!!!!

Jesus Christ! You guys and your strawmen.....hahahaha!!!

Where do you make this stuff up from?

Can you show me once whereI've denied that sound doesn't travel faster in steel??

Because I do not disagree with that, what I disagree with is that this is the explanation for Rodriguez hearing the explosions underneath him.
QUOTE (Grasshopper+Oct 22 2007, 03:42 PM)

Are you saying that at the moment of collapse there was no "explosive sound?"

Correct.

If you listen to the various sound tracks there is none of the classic BANG BANG BANG of HE going off (as you clearly hear in, for instance, the Hudson CD video) prior to the obvious downward movement of the towers.

Arthur
Grasshopper
QUOTE (adoucette+Oct 22 2007, 08:06 PM)
Correct.

If you listen to the various sound tracks there is none of the classic BANG BANG BANG of HE going off (as you clearly hear in, for instance, the Hudson CD video) prior to the obvious downward movement of the towers.

Arthur

Just wondering. That kind of makes some of the discourse here quite comical then

But of course, misunderstandings are misunderstandings, I suppose...
David B. Benson
QUOTE (stundie+Oct 22 2007, 01:02 PM)
Because I do not disagree with that, what I disagree with is that this is the explanation for Rodriguez hearing the explosions underneath him.

That's not what he originally said.

He stated that it sounded like somebody moving furniture on the floor below.

His story later became more alarmist.
QUOTE (stundie+Oct 22 2007, 03:26 PM)

Fires in the lobby?? hahahahaha!! Have you seen the Naudet film?? Firefighters are not tackling a blaze in the lobby??

Please show us the path of your magic fireball and explain how it damaged the lobby and basement, yet it didn't damage any other floors between!!

http://i117.photobucket.com/albums/o72/ard...levators-3d.jpg

Note, those right most shafts run from the impact floors straight to the basement.

Of course there was no sustained blaze in the lobbies. They weren't particularly flamable, but Naudet claims he didn't film two burning victims in the WTC 1 lobby because "no one needed to see that".

Arthur
David B. Benson
Here are the results of running several hypotheses (differential equations) on the portion of poster OneWhiteEye's antenna tower data starting at a nominal t0 = 3.93 seconds at which point to antenna tower had dropped another 0.2 meters, approximately, compared to the zero time of the data set:

CODE

BV-const-F-const-stretch             dB= 0.0 sd=  3.078

BV-const-F-no-stretch                dB= 0.0 sd=  3.078
BV-const-F-lin-stretch               dB= 0.0 sd=  3.078
mB-const-F-no-stretch                dB= 0.1 sd=  3.088
BV-lin-F-const-stretch               dB= 0.2 sd=  3.095
BV-const-F-stretch0.14               dB=44.7 sd= 11.797
BV-const-F-stretch0.18               dB=46.0 sd= 12.265

Notice that the last two hypotheses, involving fixed stretches, are very strongly rejected, with large decibans in comparison to the first hypothesis. But the next four are essentially as good as the first one.

Here are the results for considering the data just up to t0+3.0 seconds, which was as far as the previous study had data:

CODE

BV-const-F-no-stretch                dB= 0.0 sd=  3.262

BV-const-F-lin-stretch               dB= 0.0 sd=  3.262
BV-const-F-const-stretch             dB= 0.0 sd=  3.263
BV-lin-F-const-stretch               dB= 0.0 sd=  3.265
mB-const-F-no-stretch                dB= 0.0 sd=  3.267
BV-const-F-stretch0.14               dB=23.4 sd=  8.035
BV-const-F-stretch0.18               dB=24.1 sd=  8.229

There is little difference. The last two hypotheses remain strongly rejected.

Unless there are questions, I'll not go into further detail.

I believe I am ready to consider the next set of data, which includes values taken on the north wall.
OneWhiteEye
QUOTE (David B. Benson+Oct 22 2007, 10:42 PM)
Unless there are questions, I'll not go into further detail.

I will have some questions, but I just started with an earlier recommendation you made to someone else.
QUOTE (wcelliott+Oct 22 2007, 12:50 PM)
Stundie -

From Wikipedia - "Thus in steel the speed of sound is approximately 5100 m·s-1."
The speed of sound in air is about 340m/s.

Thus, in the WTC towers, a mechanical failure of steel under load happening 1000feet up in the air will be coupled to the structural steel and be transmitted down the structure at a rate of 5,100m/s, while the sound propagating through the air of the same event would be travelling the same 1000 feet at 340m/s, so the shock wave through the steel arrives in 0.06seconds, while the sound through the air arrives in 0.90 seconds.

HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA!!!!

http://www.americanscientist.org/template/...ge/1?&print=yes

High-speed Imaging of Shock Waves, Explosions and Gunshots
New digital video technology, combined with some classic imaging techniques, reveals shock waves as never before

Gary S. Settles

Shock waves were recognized as a natural phenomenon more than a century ago, yet they are still not widely understood. They are responsible for the crash of thunder, as well as the bang of a gunshot, the boom of fireworks, or the blast from a chemical or nuclear explosion. But these are not just loud noises. Sound waves can be thought of as the weaker cousins of shock waves in the air: They are both pressure waves, but they are not the same.

Shock waves play important roles in modern physics and engineering, military operations, materials processing and medicine. Historically, the study of shock waves has taught us much about the properties of gases and material responses to a sudden energy input, and has contributed to the development of gas lasers and the field of plasma dynamics.

Recent attacks by terrorists using improvised explosive devices have reinforced the importance of understanding blasts, explosions and the resulting shock waves. These waves can be powerfully damaging in their own right, but in addition, studying them can help to quantify their originating explosions and can provide insight into how buildings and airplanes can be hardened to resist damage resulting from such blasts.

.................( further into the article )

But strong shock waves are also devastating to structures. In the 1995 terrorist bombing of the Murrah Federal Building in Oklahoma City, a huge truck bomb was detonated only a few meters from the building. The resulting strong shock wave and its many concomitant effects destroyed the columns supporting the north face of the building, whence it collapsed. As a result, 168 lives were lost and there were many more injuries. Both experiments and computational blast simulations now help inform building designers on how to mitigate such lethal effects and how to prevent building collapse and improve survivability.

.................( and also )

Even after several costly full-scale blast experiments involving real airplanes, the gas-dynamics of explosions onboard commercial aircraft remains poorly understood. Better understanding is needed if aircraft are ever to be hardened against catastrophic in-flight failure resulting from explosions, whether deliberate or accidental. Interior explosions in aircraft (as in buildings) are complicated by shock-wave reverberation from interior surfaces. In 1988, the wreckage of Pan Am Flight 103 in Lockerbie, Scotland, at first seemed to show the effects of multiple simultaneous blasts at various fuselage locations. As investigations progressed, it was realized that shock waves had traveled the length and breadth of the fuselage, sometimes reflecting and thus causing local blowouts remote from the actual terrorist bomb located in the forward cargo hold.
metamars
I've taken a look, in the last couple of days, at a paper called Experimental and Theoretical Studies of Columns Under Axial Impact by Ari-Gur, Weller and Singer (pub. in Int. J. Solids Structures Vol. 18 No. 7 pp619-641 1982)

This paper has relatively simple derivations of displacements due to buckling of columns under a dynamic load. Theory was tested by means of a drop hammer device (similar to Calladine and English). Simple, that is, compared to the derivations in the book Impact - The Theory and Physical Behaviour of Colliding Solids by Werner Goldsmith. Agreement with experiment is good.

A 'Dynamic Load Amplification Factor' (DLF) is defined, as the ratio of the dynamic buckling strain divided by the static buckling strain. For a WTC scenario, of course, the equations within the paper will need to be solved numerically, after being suitably adjusted. However, for the test specimens used, we can see that DLF varied from 3.0, for a test specimen of effective slenderness of 103, test specimen mass of 108 grams, striking mass of 370 grams, and striking velocity of 8.97 m/s up to a DLF of 30.6 for a effective slenderness of 411, specimen mass of 99 grams, and striking mass of 332 grams, and striking velocity of 5.1 m/s.

I don't what the limits are of this theory - in particular, what happens when we scale up to column segments of the size found in the WTC, and with a smaller slenderness ratio. Also, I'm not sure that we can use this theory to determine energy dissipation in a dynamic strike.

However, it looks like we can use this theory to determine a DLF, determine a reasonable figure for deflection in a WTC scenario column when the upper end is not axially constrained, and thus compute the expected deflection from the dynamic load.

The final step is comparing this deflection to the maximum obtained from a static load, the theory of which Newton's Bit described.

If it turns out that the dynamic deflection is less than the maximum possible expected in the static case, we are done. Collapse, as per the BZ scenario, cannot ensue.

Otherwise, we will have to pursue a deeper theory which takes into account more dynamic effects, all of which dissipate energy.

Of course, since all of the dynamic effects are energy sinks, we already know that the Bazant Zhou claim of most optimistic is false. However, unless the details are worked out, we don't know how false. E.g., it may turn out that we get a Wg/Wp_dynamic ratio of 4x, instead of value they claimed (about 8x for Wg/Wp_static, IIRC). Such a value would imply global collapse, so we are forced to look at deeper theories to settle the matter.

So, maybe we will need to digest Goldsmith, eventually, anyway.
wcelliott
What columns were impacted axially?

I don't see any instance where that study applies in the WTC collapse.
Metamars has been on a multiyear campaign to try to discredit Bazant.

He has, of course, failed MISERABLY.

Here are a few recent highlights:

QUOTE
we already know that the Bazant Zhou claim of most optimistic is false

The real question is, how is it that the Bazant Zhou paper was published to begin with

The Bazant Zhou paper proves nothing about the real world collapses

I have tentatively concluded that Bazant's original paper with Zhou was not merely premature, but wrong in ways that Bazant must have known at the time he wrote the paper. If he is propagating a fraud, the question arises as to why he would do so.

Seeking Information on CIA contracts awarded to Northwestern University Civil Engineering Dept.
I have learned that the CIA used to smuggle cement trucks in from behind the iron curtain, with a view to having the cement analyzed. The place mentioned to me where these trucks* were studied was Northwestern University.
I am curious as to who benefited from any (presumed)** CIA contracts.
In particular, I am curious as to whether Dr. Bazant was one such recipient.

I have dismissed the Bazant Zhou paper,

It wouldn't surprise me if neither Bazant, Lee, Greening or Benson are interested in determining how valid their results might be when more realistic assumptions about energy loss through seismic disturbance is factored in. After all, none of you seems terribly interested in energy losses away from the crushing front, due to dynamic effects ala Caladine and English.

the avoidance behavior exhibited by Bazant and others implies that "respectable" journals in the US will do so, also. Specifically, I would not expect them to publish Gordon, though his paper is clearly better than BZ's.

You also had an opinon about Bazant Zhou, which, as far as I know, you haven't retracted, though their "elastic dynamic analysis" was shown to be a bad joke.

beyond a few millimeters, BZ's "elastic dynamic analysis" has little to do with physical reality. Whether intentional or not, it's propaganda.

It escapes you, does it, why the opinion of the co-publisher of a technical paper that mentions elastic dynamic analysis, but fails to mention that it has no validity beyond a few millimeters, at least in the way that BZ used it, should not have greater weight than that of Charlie Sheen?

Thus, while Bazant (and Zhou) should have something useful to offer wrt to certain aspects of the 911 attacks, in point of fact, they don't.

I have a bachelor's degree in physics and mathematics. I also have 18 graduate credits in applied mathematics, including a course in perturbation theory. Which is one reason I was immediately suspicious of the Bazant-Zhou paper.

Bazant Zhou's paper included an "elastic dynamic analysis" part that was completely misleading

I also mistakenly mischaracterized their entire paper as employing "elastic dynamic analysis",

Always good for a laugh.

Arthur

David B. Benson
QUOTE (OneWhiteEye+Oct 22 2007, 07:28 PM)
I will have some questions, but I just started with an earlier recommendation you made to someone else.

Given a calculated point, c, and a data point, d, (at the same time instant), I assume that the difference c-d is a normally distributed random error with mean zero and known variance. So Prob(c-d) is easily computed. I further assume that these are independent random variables (hence this is naive Bayesian inference) so that the probability of the entire set is the production of the individual probabilities.

While naive, this technique often works well even in cases where non-independence is known to hold.

However, the exact results are still open to question. I just found one mistake in the program, so we have the somewhat different results

CODE

BV-const-F-lin-stretch               dB= 0.0 sd=  3.000

BV-const-F-const-stretch             dB= 0.0 sd=  3.000
BV-lin-F-const-stretch               dB= 0.0 sd=  3.000
BV-const-F-no-stretch                dB= 0.0 sd=  3.000
mB-const-F-no-stretch                dB= 0.2 sd=  3.018
BV-const-F-stretch0.18               dB=29.7 sd=  7.321
BV-const-F-stretch0.14               dB=32.9 sd=  8.063

which still does not feel right, since what is last by this analysis does very well using the original, smaller data set. I don't yet see what else is wrong with the program, but expect revisions to the results.
David B. Benson
Here is a wordy introduction to Bayesian reasoning. My well be a good starting point for someone unfamiliar with this potent tool.

An Intuitive Explanation of Bayesian Reasoning
einsteen
btw anyone seen and heard this wtc7 clip, put your volume button high.

David B. Benson
Here are better, but still not great, estimates for various hypotheses (force as a function of drop, etc.) in two parts. The first is for the time up to t0 (at which point the tower had collapsed about 20 cm). The hypothesis labeled safe is the assumption that there is no collapse at all.

CODE
mB-lin                   dB= 0.0 sd= 0.031
all      sD= 0.031 mD= 0.000 skew=~0.3 kurtosis=18.4
first    sD= 0.044 mD= 0.001 skew=~0.2 kurtosis= 7.8
second   sD= 0.000 mD=~0.000 skew= 0.0 kurtosis=~21962866932784300.0

BV-lin                   dB= 0.4 sd= 0.034
all      sD= 0.034 mD= 0.003 skew= 2.2 kurtosis=12.3
first    sD= 0.047 mD= 0.008 skew= 1.3 kurtosis= 4.4
second   sD= 0.000 mD=~0.002 skew=67431445.1 kurtosis=3202918094364370.0
BV-exp                   dB= 0.5 sd= 0.035
all      sD= 0.035 mD= 0.003 skew= 2.5 kurtosis=11.8
first    sD= 0.048 mD= 0.009 skew= 1.5 kurtosis= 4.0
second   sD=   nan mD=~0.003 skew= nan kurtosis=~128116723774575000.0
mB-const                 dB= 0.5 sd= 0.035
all      sD= 0.035 mD= 0.003 skew= 2.6 kurtosis=11.7
first    sD= 0.048 mD= 0.009 skew= 1.5 kurtosis= 4.0
second   sD=   nan mD=~0.004 skew= nan kurtosis=~5948276460962410.0
BV-const                 dB= 0.5 sd= 0.035
all      sD= 0.035 mD= 0.003 skew= 2.6 kurtosis=11.7
first    sD= 0.048 mD= 0.009 skew= 1.5 kurtosis= 4.0
second   sD= 0.000 mD=~0.004 skew=86162402.1 kurtosis=6062666392903990.0
safe                     dB= 9.2 sd= 0.213
all      sD= 0.074 mD=~0.199 skew= 2.8 kurtosis= 7.2
first    sD= 0.097 mD=~0.173 skew= 1.6 kurtosis= 1.6
second   sD= 0.000 mD=~0.226 skew=50346648.8 kurtosis=3137552418969180.0

The line labeled all is some statistics for all the data used. The other two lines are the same statistics for the first and seconds halves of the data, respectively. I'll explain if requested, but the mD is the mean difference between the computed values and the data. The safe hypothesis is substantially rejected, but all the rest are about the same.

For the progressive collapse we have

CODE
BV-const-F-lin-stretch   dB= 0.0 sd= 0.364
all      sD= 0.361 mD=~0.040 skew=~0.5 kurtosis= 7.4
first    sD= 0.326 mD=~0.010 skew=~3.8 kurtosis=19.8
second   sD= 0.396 mD=~0.070 skew= 1.5 kurtosis= 1.9

mB-const-F-no-stretch    dB= 0.7 sd= 0.427
all      sD= 0.414 mD= 0.103 skew=~0.3 kurtosis= 0.4
first    sD= 0.397 mD= 0.263 skew=~1.6 kurtosis= 3.9
second   sD= 0.368 mD=~0.060 skew= 0.9 kurtosis= 0.9
BV-const-F-const-stretch dB= 2.3 sd= 0.634
all      sD= 0.594 mD= 0.219 skew=~0.2 kurtosis=~1.1
first    sD= 0.498 mD= 0.485 skew=~0.7 kurtosis=~0.4
second   sD= 0.566 mD=~0.052 skew= 0.3 kurtosis=~0.7
BV-const-F-no-stretch    dB= 2.3 sd= 0.634
all      sD= 0.594 mD= 0.219 skew=~0.2 kurtosis=~1.1
first    sD= 0.498 mD= 0.484 skew=~0.7 kurtosis=~0.4
second   sD= 0.566 mD=~0.052 skew= 0.3 kurtosis=~0.7
BV-lin-F-const-stretch   dB= 2.4 sd= 0.643
all      sD= 0.610 mD= 0.202 skew=~0.3 kurtosis=~1.0
first    sD= 0.498 mD= 0.485 skew=~0.8 kurtosis=~0.4
second   sD= 0.583 mD=~0.086 skew= 0.3 kurtosis=~0.8
BV-const-F-stretch0.18   dB=11.1 sd= 5.395
all      sD= 2.998 mD= 4.462 skew= 0.0 kurtosis=~1.2
first    sD= 1.613 mD= 1.943 skew= 0.1 kurtosis=~1.4
second   sD= 1.529 mD= 7.034 skew= 0.3 kurtosis=~1.2
BV-const-F-stretch0.14   dB=11.8 sd= 6.275
all      sD= 3.470 mD= 5.201 skew=~0.0 kurtosis=~1.2
first    sD= 1.872 mD= 2.281 skew= 0.1 kurtosis=~1.4
second   sD= 1.744 mD= 8.183 skew= 0.3 kurtosis=~1.2

where we see that the last two are strongly rejected, but by decibels alone nothing further can be done to choose the best approximation.

This still remains strange, since the last hypothesis fits the previous (shorter) data with a sd of less than 2. Of course, there might be a error in that program, but it is more likely that there is still some bug in the current one.

Using a large (positive) kurtosis as indicating a good fit to the data, we could try to argue that the first hypothesis is indeed a better fit than the remainder.

More tomorrow.
QUOTE (einsteen+Oct 23 2007, 03:37 PM)
btw anyone seen and heard this wtc7 clip, put your volume button high.

Trouble is its highly edited.

It would appear it was done to make it appear that the loud sounds are concurrent with the collapse.

They weren't.

First the east mechanical penthouse sinks into the structure and then ~ 6 seconds later, the west penthouse, and then finally comes the general collapse.

The video JUMPS from the start of the east mech collapse to well into the general collapse.

Arthur

RealityCheck
QUOTE (stundie to adoucette+Oct 22 2007, 07:26 PM)
....
....
....
So you know what a "fire induced collapse" is? Even though there as never been any reported fire induced collapses of large building before or after 9/11??

You just make this up as you go along don't you Arthur!! hahahahaha!!

Oh...Sorry have you a rebuttal of Gordon Ross paper on the WTC??

Oh and please do not even think of quoting Newtons Bit from over at the SLC and JREF forum. I've embarrassed him and Metamars  (I believe he is a member here too!) points out whats wrong with Newtons rebutal.

Didn't that (hotel?) fire in Madrid have a substantial STEEL structure upper floors section surrounding a concrete core...and didn't that core survive while the STEEL STRUCTURE COLLAPSED from FIRE effects?....even though it had nowhere near the 'to scale' LOADING, NONE of the FLOOR SPANNING vulnerabilities and NONE of the IMPACT DAMAGE or the WIDESPREAD fuel fed/started FIRE of the upper WTC tower sections that collapsed?

And as for gordon's 'analysis'....he failed to correctly treat the energy/forces pathways/reflections and temporarily recovered-recycled energies in that tumult...and especially couldn't tell what damage was done BEFORE all 'momentum' was FINALLY accounted for by ground impact....and failed to SEPARATE his analysis and treat the collapse as TWO (effectively) isolated processes/events-------one: interior collapse; the other: exterior wall 'separation'-------due to rapid floor-wall connections failure WITHOUT capability to transmit any 'axial crushing' forces from internal collapse to wall columns).

Until he does all that, and CORRECTLY, his work is not really at all RELEVANT to WTC events.

Cheers all!

RC.
.
Al Khwarizmi - step-by-step
Arthur:
=================
The dust jets were LOCALIZED, as in one window.
==================
And the localized EXPLOSIVE EJECTIONS OF MASS PRIOR TO COLLAPSE helps support your non-explosives case HOW exactly, Arthur?

wcelliot:
In striving to account for reports of explosions while denying the capacity of modern recording equipment to record anything useful, you have generated a breathtaking volume of nonsense.

A review of acoustic realities is necessitated by your repeated counterfactual assertion that audible sounds produced in the wake of an explosion result from an ultrasonic spike bouncing around the environment, and because Trippy is now suggesting that his infrasonic N-wave left home with an initially much-higher frequency that was lowered during "dispersion" - !!!!

1) A singular pressure pulse at an inaudible frequency bouncing around the local environment would not maintain amplitude for long enough to account for the audible noises that endure in the wake of a real explosion.

2) An inaudible megahertz pulse will not be shifted from ultrasonic to infrasonic during propogation in any case, since frequency, unlike amplitude, is unaltered by distance.

3) The initial blast "wave" or shock "wave" or "pressure pulse" produced by a high-speed explosive is not a sound "wave."

4) To extract useful information on the duration and amplitude of the pressure pulse produced by an explosion does not required a microphone, and I do not believe your unsubstatiated claim that DARPA requested the development of such a thing.

5) the number of supporting references you provide seems to be directly related to the truth-value of your claims.
====================

NeoFonze - thanks for the clarification of Trippy's "seemingly logical" but unfounded and unreferenced assertion regarding sulphur and the use of thermate at ground zero.
Perhaps you recall me being scorned by members of your team for my suggestion that thermite may have been used for just this purpose.

Over the next week I will be reviewing the following:
================================
Some Physical Chemistry Aspects of Thermite, Thermate, Iron-
Aluminum-Rich Microspheres, the Eutectic, and the Iron-Sulfur
System as Applied to the Demise of Three World Trade Center
Buildings on 9/11/2001
By
Jerry Lobdill
June 15, 2007

This paper deals with the incendiary events and the forensic evidence that remains to prove that the official story is wrong. Specifically, this paper discusses the chemistry of iron-aluminum-rich microspheres that are found in the dust from the rubble, the chemical content of these microspheres and the physical chemistry of the iron-sulfur-oxygen system since sulfur is one of the omnipresent elements in the iron-aluminum-rich microspheres and was also found in a metallurgical study of structural iron from the WTC 72.
http://www.journalof911studies.com/volume/...hemistryWTC.pdf
=================================
& this
(edited to add a url for Arthur)
Al Khwarizmi - step-by-step
QUOTE
Trippy:
I think (one of) the points that's being missed by the conspiracy theorists ...
(Attacks Held To Be A Conspiracy, LATimes, September 11, 2001)
...on the thread is that all single impulse events, irrespective of whether you're talking about [wcelliot's] 4 inch brick of C-4 going off, a wing snapping, a floor pan failing, or someone beating on a drum, all bare features that look the same on a spectrogram, because they're all cause by the same process - the sudden transfer of large quantities of energy to the atmosphere.

Shagster:
"On stairwell B, after the noise of collapse—one fireman said he heard each floor come down, like a drum roll—the narrow space was quiet and almost completely dark. Dust and ash clogged the air."

Shagster:
On the 'Inside the Twin Towers' DVD documentary he described the pancaking floors as sounding like a train off its rails and hitting the ties.

Indeed! It is virtually impossible to distinguish between the sound of a drum roll (all drums sound the same) from the sound of a train coming off the rails, or for that matter from the sound produced in the wake of an explosion! Samples of train crashes, explosions, guitar strings snapping, aircraft wing tests, and some really heavy "things falling on the floor from above" can all be found masquerading as drums in many modern recordings, in fact. This is precisely because almost any sound produced in almost any fashion can be used as a cheap and indistinguishable alternative to the real thing!

Inversely, I sampled real drums to mimic the sound of WMD explosions for this hypo-eutectic hip-hopumentary record.
Compare the drumy resemblance to explosions for yourself!

Still surprised that people reported being thrown to the ground and burnt by drum blasts, Trippy?

btw - here is the subsonic context for the graph that you refused to reference:
wcelliott
QUOTE
5) the number of supporting references you provide seems to be directly related to the truth-value of your claims.

Funny, nothing that you said was right.

A 10microsecond pulse reflecting off multiple surfaces will generate a "pulse" that's made up of the summation of those reflections, and the summation *is* long enough that it has features that can be heard at bandwidths below that of the original 10 microsecond pulse. The downward-slope of that "N" wave is precisely that. Without those multiple reflections, all you'd have would be the 10 microsecond "|" of the initial blast heard via the direct path.

So, are you saying that you think a 4-inch block of C-4 takes longer than 10 microseconds to detonate?

How long, exactly?

And please explain how you think explosives work, if not by releasing all their energy in a very short amount of time.
NEU-FONZE
Al Khwarizmi:

The trouble with the paper by Jerry Lobdill, as I recall, is that he talks about microspheres in WTC dust but he fails to provide any quantitative analytical data. This is, perhaps, not his fault because there is a paucity of such data. But there are a few X-ray spectra out there from various sources such as the USGS and apparently Steven Jones has recorded spectra for his much debated samples. HOWEVER, Jones has failed to publish tables of analytical data that I know he has - he just teases us with slide shows about microspheres! I have written to Jones several times and asked him when is he going to publish his results on this and he just goes silent on me. Until Doc Jones, (or somebody who has pertinent analytical data on this issue), publishes QUANTITATIVE results on microspheres, I believe it is a waste of time to discuss this topic.
Trippy
QUOTE (RealityCheck+Oct 24 2007, 05:42 PM)
Didn't that (hotel?) fire in Madrid have a substantial STEEL structure upper floors section surrounding a concrete core...and didn't that core survive while the STEEL STRUCTURE COLLAPSED from FIRE effects?....even though it had nowhere near the 'to scale' LOADING, NONE of the FLOOR SPANNING vulnerabilities and NONE of the IMPACT DAMAGE or the WIDESPREAD fuel fed/started FIRE of the upper WTC tower sections that collapsed?

And as for gordon's 'analysis'....he failed to correctly treat the energy/forces pathways/reflections and temporarily recovered-recycled energies in that tumult...and especially couldn't tell what damage was done BEFORE all 'momentum' was FINALLY accounted for by ground impact....and failed to SEPARATE his analysis and treat the collapse as TWO (effectively) isolated processes/events-------one: interior collapse; the other: exterior wall 'separation'-------due to rapid floor-wall connections failure WITHOUT capability to transmit any 'axial crushing' forces from internal collapse to wall columns).

Until he does all that, and CORRECTLY, his work is not really at all RELEVANT to WTC events.

Cheers all!

RC.
.

I mentioned that.

The fire in Madird in 1997, and there was an interstate highway in 2005 that collapsed, it was a steel structure, and it collapsed purely as a result of the fire. This is one of the things that the conspiracy theorists regularly like to lie about. And the point has been very conveniently ignored by the conspiracy theorists on this thread, not a single one of them has even attempted to address it.

The madrid fire, the upper stories were steel, the lower stories were steel reinforced concrete, the steel reinforced concrete lower stories survived, while the steel upper stories collapsed.
David B. Benson
shagster or OneWhiteEye or einsteen --- How about a "smear-o-gram" of the top of an actual controlled implosion?

For contrast with WTC 1.
Alan (ex elevator man)
QUOTE (Trippy+Oct 24 2007, 11:53 AM)
...and there was an interstate highway in 2005 that collapsed, it was a steel structure, and it collapsed purely as a result of the fire. This is one of the things that the conspiracy theorists regularly like to lie about. And the point has been very conveniently ignored by the conspiracy theorists on this thread, not a single one of them has even attempted to address it.

That was ealier THIS year, in April. Someone commented on it about weapons of mass transportation. haha

tanker fire destroys freeway overpass

One of the 18 posted pictures at the article above.
Alan (ex elevator man)
This one's even better...

fire destroying the steel overpass
OneWhiteEye
QUOTE (David B. Benson+Oct 24 2007, 08:31 PM)
shagster or OneWhiteEye or einsteen --- How about a "smear-o-gram" of the top of an actual controlled implosion?

For contrast with WTC 1.
QUOTE (Al Khwarizmi - step-by-step+Oct 24 2007, 03:33 AM)
Arthur:
=================
The dust jets were LOCALIZED, as in one window.
==================
And the localized EXPLOSIVE EJECTIONS OF MASS PRIOR TO COLLAPSE helps support your non-explosives case HOW exactly, Arthur?

NIST did NOT describe them that way, and since they also state that "there was NO EVIDENCE of explosives" its pretty clear that NIST did not believe that the DUST, SMOKE and a large piece of debris ejected from window 77-355, on the 77th floor was the result of EXPLOSIVES.

See NIST - NCSTAR 1-5A Chap 9 (time 9:37)

Why does it support a NON-Explosives case?

Simple, if you set off sufficient HE to cut sufficient columns on the 77th floor (below almost all of the impact damage) of the WTC 2 tower to have an ANY STRUCTURAL IMPACT on the tower, then the results will NOT be ONE piece of debris flying out ONE friggin window.

Arthur
einsteen
I came home at night and created some smear-o-grams, it almost could be a blues song. But when I refreshed my browser I saw the OneWhiteEye man was faster

http://i20.tinypic.com/2irvyba.png

Maybe a nice guess game.
David B. Benson
It appears that the last bugs are gone and the final improvements made. Some of the results are interesting.

For the pre-collapse (up to about 3.9 seconds):

CODE
mB-lin                   dB= 0.0 sd= 0.032
A=182.6124 Zok=0.1747

BV-lin                   dB= 0.0 sd= 0.032
A=178.5621 Zok=0.1747
BV-exp                   dB= 0.5 sd= 0.036
A=0.3980 Zok=0.1722 B=7.6566
mB-const                 dB= 0.5 sd= 0.036
F0=0.0077
BV-const                 dB= 0.5 sd= 0.036
F0=0.0077
safe                     dB= 9.2 sd= 0.218

with the assumption of a constant insufficiency of resistive force of some interest, in that F0=0.0077 means that the force was insufficient by just 0.77%.

For the progressive collapse phase:

CODE
BV-const-F-sq-stretch    dB= 0.0 sd= 0.260
F0=0.0717 S0=0.1998 S1=~2.6748

BV-const-F-lin-stretch   dB= 0.5 sd= 0.295
F0=0.0690 S0=0.1681 S1=~2.4433
BV-sq-F-sq-stretch       dB= 1.6 sd= 0.385
F0=0.0615 F1=~0.7571 S0=0.0063 S1=~0.0625
BV-lin-F-sq-stretch      dB= 1.6 sd= 0.385
F0=0.0615 F1=~0.7571 S0=0.0063 S1=~0.0625
mB-const-F-no-stretch    dB= 1.9 sd= 0.415
F0=0.0592
BV-const-F-const-stretch dB= 3.8 sd= 0.656
F0=0.0520 S0=0.0000
BV-const-F-no-stretch    dB= 3.8 sd= 0.656
F0=0.0520
BV-lin-F-const-stretch   dB= 3.8 sd= 0.656
F0=0.0520 F1=0.0000 S0=0.0000
BV-const-F-stretch0.14   dB= 4.1 sd= 0.708
F0=0.0505
BV-const-F-stretch0.18   dB= 4.2 sd= 0.726
F0=0.0500

so that none of these hypotheses can be rejected! The most likely hypothesis (but not by much) has a constant force amounting to 0.0717/0.1747 = 0.41 of enough o hold the tower up. The stretch starts at S0, about 0.20, and decreases with the square of the increasing speed.
shagster
429 Truth. Some refer to it as 'Loose Interchange'.

http://www.429truth.com/

einsteen
#2 is wtc7, #3 is the 2nd largest building ever imploded, the Landmark Tower, the other ones some random implosions. If you look at #4 I can only conclude that given the resolution we have there cannot be extracted more information than there is and that it is indistinguishable from the wtc1 graphs we have seen. And personally I don't think it is possible to see difference because it is always gravity that does the work and that will, with just sufficient catalysts, at a certain moment takes over the situation, it will always start slowly because it is a huge mass that needs to be accelerated.
shagster
Smear of WTC7. This is from CBS footage many blocks north and elevated view. The blue and white are the CBS graphics. I took a vertical slice at the position where the top of the building can be seen all the way down to near the ground level.

larger image:

http://i134.photobucket.com/albums/q91/sha...tc7/wtc7cbs.jpg

shagster
The slope of the line formed by the roof appears to decrease slightly near the ground level. I don't know if that is due to parallax effects or if the speed of the roof actually decreased slightly as it neared the ground level (or both). Someone would need to look at all the issues that affect the shape of the smear.
shagster
QUOTE (einsteen+Oct 25 2007, 01:15 PM)
#2 is wtc7, #3 is the 2nd largest building ever imploded, the Landmark Tower, the other ones some random implosions.

I assume #2 is the upper right in that pic.

shagster
I probably have the full resolution CBS footage of WTC7 in my VCR tapes. I'll try to dig it up and do a more detailed smear.

I have a CBS book and DVD called What We Saw. Maybe the WTC7 footage is in there.
einsteen
QUOTE (shagster+Oct 25 2007, 02:01 PM)
I assume #2 is the upper right in that pic.

Indeed, I had to number them
einsteen
ps. and why can't we edit old posts ? I mean #3 instead of #4 two posts before this one
David B. Benson
Thank you three for the smears.
David B. Benson
Regarding WTC 7 (.pdf file)

Analysis by Scheuerman
OneWhiteEye
QUOTE (einsteen+Oct 25 2007, 01:15 PM)
#2 is wtc7, #3 is the 2nd largest building ever imploded, the Landmark Tower, the other ones some random implosions. If you look at #4 I can only conclude that given the resolution we have there cannot be extracted more information than there is and that it is indistinguishable from the wtc1 graphs we have seen.

Two charts follow with a green and blue curve each. One of the curves is the Landmark, the other is WTC1. Time and distance have been normalized to the range 0-1. Which one is which?

http://i20.tinypic.com/j607id.jpg

http://i20.tinypic.com/11kayb8.jpg
David B. Benson
QUOTE (OneWhiteEye+Oct 25 2007, 12:56 PM)
... Which one is which?

It would help to have the normalized time axis use the same normalization for both curves. Also the blue curve doesn't seem to have the first few beginning points. Why is that? (Without giving the game away.)
OneWhiteEye
QUOTE (David B. Benson+Oct 25 2007, 08:43 PM)
It would help to have the normalized time axis use the same normalization for both curves.
I know time and approximate distance for WTC1, but the Landmark is a mystery to me. I used einsteen's smear; I don't know the framerate or what distance pixels represent. Therefore scale in either dimension is not comparable for the two curves.

One may show greater deflection than the other in frame time while not actually being greater, if the frame rates differ significantly.

The point of stretching and squashing to the [0,1] in both dimensions is to capture the character of the curves independent of scaling. Added quadratic and cubic to one plot:

http://i23.tinypic.com/ns08p.jpg

QUOTE (David B. Benson+Oct 25 2007, 08:43 PM)

Also the blue curve doesn't seem to have the first few beginning points. Why is that? (Without giving the game away.)
It only appears that way as the blue is obscured. Both start at zero.

There is enough information for you, who has intimate knowledge of the data collection process, to make a good educated guess, independent of the values. If you use that strategy, I can't fault you. I almost gave the game away myself because I wanted to gloat about my new automated method.
David B. Benson
QUOTE (OneWhiteEye+Oct 25 2007, 02:11 PM)
There is enough information for you, who has intimate knowledge of the data collection process, to make a good educated guess, independent of the values.

Well, I don't have that much knowledge about the collection process, but I''ll guess, based on fit to quadratic, that blue is the Landmark and green is WTC 1.

Please send answer and prize money via PM so that others can play.
David B. Benson
What was the height of the office floor trusses?
einsteen
OneWhiteEye,

I used the landmark from the video below called "the third tower", this is a quite good hi-res xvid codec video. I have to say that I didn't do it very precisely, there was not an antenna to take, it was rotated a little bit (virtualdub has a free filter to rotate it back) and it depends of course where you take it, it probably had no hat truss that leads to a uniform collapse, I don't know.

E.

offline now and changing diapers...
shagster

The collapse curve for a crush-up is expected to be close to parabolic and the collapse duration is expected to be close to freefall duration when the value of E1/mh is a small fraction of g. E1 is the energy to collapse a story, m is the falling mass at any given time, and h is the story height.

If E1/mh is constant throughout a crush-up collapse, then the acceleration will be constant throughout the collapse, although smaller than freefall acceleration g, and the collapse curve will be parabolic for the entire collapse. This would require that E1 decrease with tower height such that E1/mh is the same for any position in the tower. m is the total mass above a particular story and E1 is the energy needed to collapse that particular story. The acceleration for crush-up in that case is g-E1/mh.

The total crush-up duration for constant E1/mh can be determined using the equation x = 0.5 (g-E1/mh) t^2 and solving for t knowing tower height x. If E1 is zero, then t is the freefall duration. When E1/mh is a small fraction of g, t will be close to the freefall duration.

For an E1 that is relatively constant with building height, the acceleration will decrease during crush-up. The amount of falling mass m decreases during crush-up, which increases E1/mh, which slows the collapse. The collapse curve would start out approximately parabolic but would become more linear with time as E1/mh approaches g (or E1/h approaches mg). In theory the curve would eventually tail off to a horizontal (collapse halted) at some time after E1/mh became greater than g. That tail effect would be more noticable for large values of E1/h.

shagster
The situation is different for crush-down due to the slowing effect of momentum transfer, particularly near the beginning of the collapse. The collapse curve for a crush-down would be flatter at first but would tend to approach a parabola as the collapse progressed and a large amount of falling mass accumulated at the collapse front. More mass at the front decreases the slowing effect of momentum transfer, and the large KE of the falling mass overwhelms E1. Both of those tend to make the crush-down collapse curve parabolic later in the collapse. That's roughly the opposite of what happens for a crush-up with approximately constant E1, where the acceleration decreases later in the collapse.

The above assumes no shedding, no air resistance, etc.
Al Khwarizmi - step-by-step
wcelliot
====================
A 10microsecond pulse reflecting off multiple surfaces will generate a "pulse" that's made up of the summation of those reflections, and the summation *is* long enough that it has features that can be heard at bandwidths below that of the original 10 microsecond pulse. The downward-slope of that "N" wave is precisely that.
=====================

The downward slope is not precisely "that," and you are confabulating again.

The downward slope maps the return from compression to equalibrium and beyond into rarefaction.
That's a fact even Trippy could understand, despite his posting of an INFRAsonic pulse in support of your whacky ULTRAsonic assertion.
Do you understand the difference between ULTRA and INFRA sonic yet?

Arthur posted a 3.3 millisecond pulse, the amplitude of which would have destroyed the diaphram of any microphone in its proximity, despite the fact that its frequency was within the discriminable range. This also failed to support your unreferenced assertion.

On the other hand, my 5 points, contrary to your defamatory claim, were entirely correct!

http://www.americanscientist.org/template/...ge/1?&print=yes

Shock waves were recognized as a natural phenomenon more than a century ago, yet they are still not widely understood. They are responsible for the crash of thunder, as well as the bang of a gunshot, the boom of fireworks, or the blast from a chemical or nuclear explosion. But these are not just loud noises.
Sound waves can be thought of as the weaker cousins of shock waves in the air:
They are both pressure waves, but they are not the same.
... but they are not the same.
... they are not the same.
... not the same.

=================================
Thanks, q&d!

====Arthur====
If you listen to the various sound tracks there is none of [i]the classic BANG BANG BANG of HE going off [/i]
============

====Grasshopper====
That kind of makes some of the discourse here quite comical then.
=================
QUOTE
"With the use of delays we can control, pretty much, where the debris lands; we can control vibrations; we can control noise levels. Timing and delays are just about the key to everything in our business."
- Mark Loizeaux, Controlled Demolitions Inc.
"We can control noise levels."

Are you still amused?

These spectral distribution graphs have a play button attached for the associated audio:
http://history-bytes.blogspot.com/2007/10/comparitor.html
compare, y'all.
Except Al, what he means by "With the USE OF DELAYS ... We can control sound levels" is EXACTLY the reason you get the BANG BANG BANG BANG associated with HE demolition.

Consider the ALTERNATIVE.

No Delay

Then ONE MUCH BIGGER BANG.

Which of course is MUCH MORE OBVIOUS.

Both VISIBLY and AUDIBLY

Which of course, as the sound tracks from multiple sites have shown, the collapse begins with the slow pulling in of an exterior wall and when the motion becomes obvious its well BEFORE any EXPULSIONS of high speed debris or before any loud sounds are generated by the falling structure.

One is a shaped charge set off in the open, the other is an UNKNOWN sound from an UNKNOWN source at an UNKNOWN distance.

Al, you get more desperate with each passing post.

I mean first it was 50 pages of "Dude, it wasn't 19 Arabs, the joos did it, didn't you read about the DANCING ISRAELIS"

Then it was 50 pages of "Dude, it was GLOWING YELLOW. I mean WHAT IN THE WORLD BESIDES THERMITE could POSSIBLY cause GLOWING YELLOW MATERIAL."

Now you are using as evidence the equiv of: "Dude, it was LOUD SOUNDS. I mean WHAT IN THE WORLD BESIDES EXPLOSIVES could POSSIBLY cause such LOUD SOUNDS."

Arthur
wcelliott
Al -

A point (of many) that goes straight over your head, is that the acoustic spectrum of a 10microsecond spike goes all the way from DC to a MegaHertz, so it includes spectral energy in all bands, including the audio band (40-20,000Hz). So I'm not saying that an explosive detonation is silent, I'm saying that you can hear it go off, but you can't hear anything distinctive between that and anything else that has a similar characteristics in the same audio band. It WILL have energy in the 20,000Hz to 1,000,000Hz part of the spectrum that you won't hear, though, and ordinary recording equipment won't capture.

Any notion that explosives have a characteristic waveform would require the contributions of this part of that spectrum, and ordinary recorders simply undersample this part of the "characteristic waveform" and won't reproduce it. You can still hear the 40-20,000Hz part of the waveform, but that's less than 2% of the "characteristic spectrum" of the detonation.

But, let's consider that part for a second - the spectrum of a real explosion goes all the way up to MHz frequencies, 20kHz is only 2% of the way up in frequency, but all those sonograms you provided seemed to peak-out at 10-11kHz. What happened to the 10-20kHz components?

See, with your expensive speakers, the top-end frequency response is limited by the mass of the speaker cone and the power of the speaker coil - the coil's force has to accelerate the speaker-cone mass to reproduce the high slew-rates associated with high-frequency sounds. Sound familiar? That's why the expensive speakers brag about their power and the REALLY expensive speakers brag about what their speaker cones are made of - low mass/high-rigidity materials.

But as you've pointed out, concrete floors, even ones 600x bigger across than they are thick (like a playing card) are still concrete, and that's fairly massive. Then again, the structural steel connected to that concrete was stressed to the breaking point, so the energy available to move that concrete was a lot greater than you speakers' voice-coils.

The point is, that a sudden release of mechanical energy coupled to a big floor will make a pretty good approximation of a woofer reproducing an explosion. It'll have some upper limit to its frequency response, though, so the top-end of its frequency spectrum will tend to drop off. I wouldn't expect it to go as high as 20,000Hz, would you?

But a block of C-4 definitely WOULD have higher-frequency components all the way up to the MHz.

So show us a sonogram from a WTC collapse that has spectral components in the 10kHz to 20kHz range and let's talk.

Oh, and find me a microphone that has a DC response. Without the DC component, the waveform captured MUST be balanced at zero, so that high-pressure shock wave has to go negative to balance-out the response. Otherwise, it'd be capable of detecting barometric pressure. You want to impress me, grab a book on Fourier Series and read a few chapters, you'll learn a lot about more about acoustics than you currently do.
David B. Benson
shagster --- Thanks, but for crush-down that appears to depend upon assuming a constant stretch. I'm getting the best results using a constant force together with a stretch which starts at about 0.3 and decreases with the square of the increasing speed. This gives an amazingly precise fit to the data, the standard deviation is only 20 centimeters.
Trippy
QUOTE (Al Khwarizmi - step-by-step+Oct 26 2007, 11:54 PM)
Trippy could understand, despite his posting of an INFRAsonic pulse in support of your whacky ULTRAsonic assertion.
Do you understand the difference between ULTRA and INFRA sonic yet?

Buzz off, and keep your arrogance to yourself.

Having dealt with UV-VIS and NIR spectroscopy, I'm well aware of the distinction between Infra- and Ultra.

I notice you're still avoiding the Sonograph that I posted earlier.

What's the matter? Afraid to admit that it bares the same features as the controlled demo, and the WTC collapse (well, the ones pointed out by the guy who did the analysis anyway).
Chainsaw,
QUOTE (Al Khwarizmi - step-by-step+Oct 26 2007, 10:54 AM)
wcelliot
====================
A 10microsecond pulse reflecting off multiple surfaces will generate a "pulse" that's made up of the summation of those reflections, and the summation *is* long enough that it has features that can be heard at bandwidths below that of the original 10 microsecond pulse. The downward-slope of that "N" wave is precisely that.
=====================

The downward slope is not precisely "that," and you are confabulating again.

The downward slope maps the return from compression to equalibrium and beyond into rarefaction.
That's a fact even Trippy could understand, despite his posting of an INFRAsonic pulse in support of your whacky ULTRAsonic assertion.
Do you understand the difference between ULTRA and INFRA sonic yet?

Arthur posted a 3.3 millisecond pulse, the amplitude of which would have destroyed the diaphram of any microphone in its proximity, despite the fact that its frequency was within the discriminable range. This also failed to support your unreferenced assertion.

On the other hand, my 5 points, contrary to your defamatory claim, were entirely correct!

http://www.americanscientist.org/template/...ge/1?&print=yes

Shock waves were recognized as a natural phenomenon more than a century ago, yet they are still not widely understood. They are responsible for the crash of thunder, as well as the bang of a gunshot, the boom of fireworks, or the blast from a chemical or nuclear explosion. But these are not just loud noises.
Sound waves can be thought of as the weaker cousins of shock waves in the air:
They are both pressure waves, but they are not the same.
... but they are not the same.
... they are not the same.
... not the same.

=================================
Thanks, q&d!

====Arthur====
If you listen to the various sound tracks there is none of [i]the classic BANG BANG BANG of HE going off [/i]
============

====Grasshopper====
That kind of makes some of the discourse here quite comical then.
=================
"We can control noise levels."

Are you still amused?

These spectral distribution graphs have a play button attached for the associated audio:
http://history-bytes.blogspot.com/2007/10/comparitor.html
compare, y'all.

The medium the wave travels though effects the waves propagation rate, shock waves from thunder produce supersonic sound waves, the supersonic sound waves are heard after the shock wave traveling though the ground is felt.

Your arguing simple wave propagation first year elementary school physics.
You also have no grasp of wave propagation, I suggest you go back to elementary school and take a refresher course.
David B. Benson
After a few more minor improvements, the best combination (but not by much) for the progressive collapse data is a resistive force which starts at about 45% and grows with the square of the speed --- along with a stretch which begins at about 0.3 and decreases with the square of the speed. This combination has a standard deviation of 0.215 meters, which is just about +/- one pixel.
OneWhiteEye
No one besides David B. Benson has the inclination or interest to take a guess on which curve is WTC1 and which one is the Landmark Tower? Honestly, I'm disappointed. Granted, it's not too meaningful to only look at the order of the curve.

How about pink and peach curves? This time, however, the units are seconds and floors. It is possible that the Landmark is 12.7 ft per floor, not so sure about that. If so, one of these curves will need a 6% scale adjustment upward to be truly comparable.

http://i21.tinypic.com/65tn9h.png
Since the curves are essentially identical, there is no rational basis for guessing which is which.

Einsteen gave a decent summary of why this is so:

http://forum.physorg.com/index.php?showtop...ndpost&p=276920

Arthur
OneWhiteEye
QUOTE (adoucette+Oct 27 2007, 03:03 AM)
Since the curves are essentially identical, there is no rational basis for guessing which is which.

Einsteen gave a decent summary of why this is so:

http://forum.physorg.com/index.php?showtop...ndpost&p=276920

Arthur

So, if I pick one of the other CD's to extract, you'd expect that the curves would match these... based on that reasoning. Correct? If not, why?
I wouldn't expect much difference.

But, if a difference was found, I suspect a closer analysis of the CD would likely show the reason.

Arthur
Trippy
QUOTE (OneWhiteEye+Oct 27 2007, 02:06 PM)
No one besides David B. Benson has the inclination or interest to take a guess on which curve is WTC1 and which one is the Landmark Tower? Honestly, I'm disappointed. Granted, it's not too meaningful to only look at the order of the curve.

How about pink and peach curves? This time, however, the units are seconds and floors. It is possible that the Landmark is 12.7 ft per floor, not so sure about that. If so, one of these curves will need a 6% scale adjustment upward to be truly comparable.

http://i21.tinypic.com/65tn9h.png

I did posit a guess, I just didn't care to posit it, for a bunch of reasons. heh.
David B. Benson
Actually, I was more interested in the pre-collapse part of the graphs. For WTC 1 there is some slow decay of about 20 cm preceding the main drop. For a CD there will be none.
wcelliott
QUOTE
Actually, I was more interested in the pre-collapse part of the graphs. For WTC 1 there is some slow decay of about 20 cm preceding the main drop. For a CD there will be none.

Exactly.
OneWhiteEye
Any more takers before I post the pre-collapse curves?
NEU-FONZE
DBB:

The only research paper I have been able to find that actually measures the rate of collapse of a building during a CD was published by E. Yarimer and C. Brown in the Conference Proceedings known as "Structures Under Shock and Impact IV" published in 1996.

The most interesting part of Yarimer and Brown's paper is their Figure 5 which shows a measured drop vs. time plot for the November 1995 CD of a 20 storey building, the Standwell East Tower, in Rowley Regis near Birmingham in the UK.

Y & B's Figure 5 shows a CD with a very flat curve for the first 1.8 seconds of the collapse. I would estimate that the total drop of the roof of the building was no more than 2 meters in the first 2 seconds of the collapse, increasing to 20 meters in the following 2 seconds. The authors speculate that the extended collapse initiation observed for this building was caused by "the progressive spreading of fractures from the charge locations to the rest of the floor before a general downward motion could begin."
OneWhiteEye
QUOTE (NEU-FONZE+Oct 27 2007, 07:05 PM)
DBB:

The only research paper I have been able to find that actually measures the rate of collapse of a building during a CD was published by E. Yarimer and C. Brown in the Conference Proceedings known as "Structures Under Shock and Impact IV" published in 1996.

The most interesting part of Yarimer and Brown's paper is their Figure 5 which shows a measured drop vs. time plot for the November 1995 CD of a 20 storey building, the Standwell East Tower, in Rowley Regis near Birmingham in the UK.

Y & B's Figure 5 shows a CD with a very flat curve for the first 1.8 seconds of the collapse. I would estimate that the total drop of the roof of the building was no more than 2 meters in the first 2 seconds of the collapse, increasing to 20 meters in the following 2 seconds. The authors speculate that the extended collapse initiation observed for this building was caused by "the progressive spreading of fractures from the charge locations to the rest of the floor before a general downward motion could begin."

Thank you. That is an extremely pertinent and useful observation.
OneWhiteEye
OK. Here both curves show the first 0.2 floors of deflection. The datasets were obtained by different methods but they have similar extraction accuracy, one method is just noisier than the other.

http://i24.tinypic.com/wu08bb.png

http://i22.tinypic.com/r0unvp.png
OneWhiteEye
I'm more interested in this:

QUOTE (adoucette+Oct 27 2007, 03:03 AM)
Since the curves are essentially identical, there is no rational basis for guessing which is which.

Einsteen gave a decent summary of why this is so:

http://forum.physorg.com/index.php?showtop...ndpost&p=276920

Arthur

NEU-FONZE has now addressed this to some degree. Would any of the other posters who've spent considerable time and intellectual effort trying to characterize the mechanics of collapse care to weigh in on this? The similarity is undeniable. David B. Benson, einsteen, shagster... is the above a sufficient explanation?

The Landmark tower was 30 stories, 380 feet, and seemed to have a substantially different architecture from WTC1. Most notably the Landmark was destroyed by controlled demolition. I can't think of two more dissimilar cases of high-rises; about the only thing they have in common is they were both buildings that had sustained sufficient damage to cause collapse.

Now, if the similarity in fall rates is not a surprise, but is instead to be expected, why the time spent tweaking this parameter and that over a period of months when the answer is so simple: any building that falls for any reason does so at an acceleration of 0.6g? With the apparent exception of CD instances which, after closer inspection, will reveal some peculiarity that separates them even more from the cases of the WTC1 and Landmark towers, now expected to show similar drop rates.

I'm not trying to exaggerate for dramatic effect or be facetious or coy. I think this deserves some more scholarly commentary before being waved away. At this time, my opinion is that it is simply coincidence, and I have no expectation of seeing the same drop rates in subsequent extractions of CDs. But then, what do I know? I'm just a layman putting a lot of time into getting this data so the associated phenomena can be better understood; all I can do is extract more CDs and put to test the theory of... universal collapse similiarity.

Perhaps we should invite Professor Bazant here. He should have an opinion on mean acceleration of collapsing buildings being centered tightly on 0.6g.
David B. Benson
QUOTE (NEU-FONZE+Oct 27 2007, 12:05 PM)
Y & B's Figure 5 shows a CD with a very flat curve for the first 1.8 seconds of the collapse. ...

Using poster OneWhiteEye's antenna tower data, WTC 1 slowly sank for about 2.4 seconds, losing about 20 cm in this time. At that point additional buckling occurred and progressive collapse commences. Still I'll be interested in comparing a controlled implosion to WTC 1, just to see.

For that early period, no single hypothesis stands out. The simplest, a constant resistive force, has a resistance only lacking 1.7% of enough to keep the tower standing.

The two best hypotheses for the progressive collapse both have the stretch decreasing with the square of the crushing front speed. One has the resistive growing linearly with the drop; the other has the resistive force growing with the square of the crushing front speed. Both agree with the data within +/- one pixel, approximately, and in the sense of the standard deviation.

However, all the other force and stretch combinations I have have tried are almost as good. I have no objective means of choosing one over another.
David B. Benson
Here is the pre-collapse WTC 1 drop data:

CODE

-3.930    0.000
-3.927    0.000
-3.269    0.022
-3.236    0.000
-3.225    0.039
-2.693    0.039
-2.583    0.000
-2.449    0.000
-2.000    0.039
-1.889    0.022
-1.848    0.000
-1.527    0.058
-1.454    0.022
-1.273    0.000
-1.097    0.022
-1.040    0.058
-0.779    0.000
-0.763    0.022
-0.626    0.039
-0.437    0.065
-0.367    0.063
-0.244    0.106
-0.197    0.130

which correctly places collapse t0 time at frame 918, agreeing with poster OneWhiteEye's observations about the video, but was selected automatically by best agreement with previous data.

Fixed a problem and now getting very good fits for all the functions, best for exponential, almost rejectable for constant and strong evidence that the structure was sinking.
wcelliott
QUOTE
For that early period, no single hypothesis stands out. The simplest, a constant resistive force, has a resistance only lacking 1.7% of enough to keep the tower standing.

I would argue that it's resistance was decreasing continuously from 101% of that needed to support the tower to 100.00%, and as soon as the resistance dropped below 100.00% to 99.999%, that the building was on the way down at that instant, its acceleration being 0.00001g when the resistive force was 99.999% of that needed to support it.

Not much displacement to notice at those low g's, but that 20cm displacement came from somewhere over the time between impact and that point...

Maybe it'd be more accurate to say that the acceleration became noticeable when the resistive force decreased to 98.3%.
David B. Benson
QUOTE (wcelliott+Oct 27 2007, 02:34 PM)
Maybe it'd be more accurate to say that the acceleration became noticeable when the resistive force decreased to 98.3%.

Yes. One of the problems is that we do not know (yet) how to make use of any data before frame 800. I suspect that already by then the antenna tower was tilted about one degree of arc, corresponding to a drop of about 50 cm.

After fixing a problem and rerunning the code, that constant is 1.4%. But this hypothesis is (almost) substantially less likely to explain the data than either an exponentially decreasing force or a linearly decreasing force. Between those two hypotheses there isn't really enough data to choose, but if I had to do so, there is a tiny advantage to the linear hypothesis.

I'll have to run all this on larger data sets before being able to say anything with confidence.

Finally, I'll admit I don't have any particularly strong reasons for just these hypotheses. I'll be happy to include some more if there are suggestions.
David B. Benson
QUOTE (OneWhiteEye+Oct 27 2007, 12:16 PM)
... He should have an opinion on mean acceleration of collapsing buildings being centered tightly on 0.6g.

By actual measurements, WTC 2 collapsed at about (3/4)g for the first four seconds.
wcelliott
QUOTE
either an exponentially decreasing force or a linearly decreasing force. Between those two hypotheses there isn't really enough data to choose, but if I had to do so, there is a tiny advantage to the linear hypothesis.
...
I'll be happy to include some more if there are suggestions.

My guess would be that it's a combination of trig functions.

Let's consider a broomstick almost perfectly balanced on one end. The descent as it tips over is:

lengthofstick*(1-cos(anglefromvertical))

The anglefromvertical is determined by the torque due to the Cg of the stick being displaced from being directly over the point of support, acting over time (double-integral of the rotational acceleration by time). At first this rotational acceleration is almost zero, because the displacement of the Cg is almost zero, but it's increasing with time.

I'm not up to doing the math, myself, but I'd think this function would be a closer fit than an exponential or a linear function, at least for the time between the resistive force dropping below 100% and the point where the accelerations are obvious.

einsteen
I'm really interested, but will comment later in more detail. Had some other things and my puter was also doing strange. I couldn't say which one was which.

Arthur referred to a post I made, I made that post but I'm not sure, I remember that if it is triggered with something some people said it must be a very sudden thing, I remember that N-F tried to fit some curves and it was exponentially and after that algebraically. The whole problem is to find information before the spontaneous fall of the building and as DBB says that should indeed be something before it, but that process before the global collapse, in the debunkers scene mentioned 20 minutes, has not really been observed. There are not much vids online that show the building 30 minutes before the collapse, but such a vid in raw format is a one that one should have.
newton
QUOTE (OneWhiteEye+Oct 27 2007, 07:16 PM)
I'm more interested in this:

NEU-FONZE has now addressed this to some degree. Would any of the other posters who've spent considerable time and intellectual effort trying to characterize the mechanics of collapse care to weigh in on this? The similarity is undeniable. David B. Benson, einsteen, shagster... is the above a sufficient explanation?

The Landmark tower was 30 stories, 380 feet, and seemed to have a substantially different architecture from WTC1. Most notably the Landmark was destroyed by controlled demolition. I can't think of two more dissimilar cases of high-rises; about the only thing they have in common is they were both buildings that had sustained sufficient damage to cause collapse.

Now, if the similarity in fall rates is not a surprise, but is instead to be expected, why the time spent tweaking this parameter and that over a period of months when the answer is so simple: any building that falls for any reason does so at an acceleration of 0.6g? With the apparent exception of CD instances which, after closer inspection, will reveal some peculiarity that separates them even more from the cases of the WTC1 and Landmark towers, now expected to show similar drop rates.

I'm not trying to exaggerate for dramatic effect or be facetious or coy. I think this deserves some more scholarly commentary before being waved away. At this time, my opinion is that it is simply coincidence, and I have no expectation of seeing the same drop rates in subsequent extractions of CDs. But then, what do I know? I'm just a layman putting a lot of time into getting this data so the associated phenomena can be better understood; all I can do is extract more CDs and put to test the theory of... universal collapse similiarity.

Perhaps we should invite Professor Bazant here. He should have an opinion on mean acceleration of collapsing buildings being centered tightly on 0.6g.

the curves are nearly identical because they are both CDs.

my forecast: expect heavy hand waving and thick fog.

NEU-FONZE
Wcelliott:

I have worked through the math of the rotational motion of a rigid body under the action of gravity. You do have the functional form [1 - cos (theta)] in the starting equations but since theta is small you can use a polynomial expansion of cos (theta) to a very good approximation.

After some manipulation you will find that the rotation of the upper section of WTC 2 is governed by the equation:

t (in seconds) = 2.86 ln { (theta) / [1.43 (d(theta)/dt)i ] }

This equation shows that for a rigid structure of known height and width tipping over under the action of gravity, the time to rotate through an angle theta depends on the log of the angle and the initial rate of rotation (d(theta)/dt)i.
wcelliott
N-F - Thanks for that, but I hadn't intended the suggestion to mean that I thought it was a literal case of something tipping over, despite the fact that there was tilt involved in both cases of the upper structure (above the impact).

My point was that the form of the equation of an almost-balanced broomstick would (my guess) be a better fit to the descent profile seen in both towers.

With a broomstick, the rate of descent has the (1-cos[theta]) term in front of a term defining where that theta comes from, and that's from a torque that starts out almost zero and increases in time, with the theta being the integral of the torque acting on the rotational moment of inertia. Small torque acting at first, increasing over time, eventually reaching a point where the descent is noticeable.

Incidentally, the equation describing what happens when a column buckles would, I think, look very similar to two of these broomsticks balanced one on top of the other, connected by a hinge with friction.
David B. Benson
QUOTE (NEU-FONZE+Oct 28 2007, 08:16 AM)
This equation shows that for a rigid structure of known height and width tipping over under the action of gravity, the time to rotate through an angle theta depends on the log of the angle and the initial rate of rotation (d(theta)/dt)i.

This suggests that using a force which has a term with an exponential in it should be the best fit. It is, but linear is almost as good. Perhaps with more data it will be possible to distinguish the two.
Trippy
QUOTE (David B. Benson+Oct 29 2007, 06:46 AM)
This suggests that using a force which has a term with an exponential in it should be the best fit. It is, but linear is almost as good. Perhaps with more data it will be possible to distinguish the two.

Why not just do a log plot? (Or an x^2 plot or a 1.x plot or whatever).

That'll tell you if it's linear or not, and the equation will fall out real easy.
David B. Benson
QUOTE (Trippy+Oct 28 2007, 10:51 AM)
That'll tell you if it's linear or not, and the equation will fall out real easy.

Well, I posted the data earlier. The statistic measures employed give essentially the same values for both hypotheses. Given that, I doubt that just eye-balling it will show that one is better than the other.

Data! I want want data. Once I have enough, perhaps the two can be separated.

As it stands, both poster NEU-FONZE's line of reasoning and also the appearance of continued, ever-increasing ever faster decay both suggest that the exponential form is correct. I'm merely reporting that there is no objective way to conclude that from the existing data.

Edited to add: Actually I have more data, the more massive data set provided by poster OneWhiteEye. I just need to vet it and use it. Then we'll see what we shall see...
David B. Benson
QUOTE (newton+Oct 27 2007, 06:42 PM)
the curves are nearly identical because they are both CDs.

No, poster newton.

One building was on fire; the other was not.

One building had exterior walls bowing-in; the other did not.

One building appears to have partial collapse of floors, several different times; the other did not.

Guess which was which?
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