The 9/11 Forum

by **OneWhiteEye** » Thu May 06, 2010 2:32 am

And this is not groupthink. Or if it is, I could give a rat's ass, so long as it's correct. And it most certainly is. If you've got a few people that have worked through this in excruciating detail (more than perhaps anyone else) and they happen to arrive at some common conclusions, how is that group think? How does having someone who hasn't studied the situation (at all, apparently) brand it groupthink - make it groupthink?

by **OneWhiteEye** » Thu May 06, 2010 2:33 am

Least action is least action. I ask you again for the force that acts in a horizontal direction to move the top off.

by **Darkwing** » Thu May 06, 2010 2:55 am

How is having someone who hasn't studied the situation (at all, apparently) branding it groupthink - make it groupthink?

No that's not what I said.

If you want to convince anybody other than yourself though, your say-so is not going to count for much. And the fact that is has been discussed before is irrelevant.

Least action is least action. I ask you again for the force that acts in a horizontal direction to move the top off.

Least action is not the direction of the biggest single force vector.

It is the direction in which the building is the weakest in. If you tell me the building is weakest to lateral forces acting on individual members, then the net force will favor lateral movement.

Any object at rest is (by definition) subject to either no force or a balance of forces from all directions. Failure can be seen as the liberation of a potential energy in a certain direction. If the building tends to fail sideways, sideways is the way it will tend to fail in.

http://www.youtube.com/watch?v=gO9CKkbL ... 1&index=25

by **OneWhiteEye** » Thu May 06, 2010 4:08 am

No that's not what I said.

What? It's still echoing off the walls.

Long time readers know we've been through this before.

Yeah, you see that's not really impressive to me:
http://en.wikipedia.org/wiki/Groupthink

I guess it was unrelated to the conversation and the quote that precedes it. Any resemblance to an accusation of groupthink is purely coincidental.

If you want to convince anybody other than yourself though, your say-so is not going to count for much. And the fact that is has been discussed before is irrelevant.

I've given you ample information to correct your misconceptions regarding classical mechanics generally and collapse mechanics specifically. You've rejected it. Nothing more I can do.

Least action is not the direction of the biggest single force vector.

Least action is the path which minimizes the integral of the Lagrangian over time. This is a means of developing equations of motion.

It is the direction in which the building is the weakest in.

Down the interior OOS, where most of the mass already is, the force due to gravity is directed, and where there are only floor slabs to stop it. Not to say things won't fall outside the footprint, but the notion that it's the only way down (or that it's least action) is not correct. This is precisely why dynamics is done with equations instead of words.

Any object at rest is (by definition) subject to either no force or a balance of forces from all directions.

Thanks for the lecture, professor.

by **OneWhiteEye** » Thu May 06, 2010 4:14 am

Honestly, I really hope your students take up the entirety of each class with rejecting everything you say because they don't understand it and don't care to, making up principles from thin air which fly in the face of every elementary aspect of your chosen field, and accuse you of group think because you quote Penrose, Jaynes, Noether, etc, or give them a final exam.

It would be good karma for you.

by **OneWhiteEye** » Thu May 06, 2010 4:50 am

by **Darkwing** » Thu May 06, 2010 6:53 am

What? It's still echoing off the walls.

Only one from my side:

http://en.wikipedia.org/wiki/Semiotics

I've had it, you guys are impossible, I really don't know what it is you hope to achieve by this kind of behavior.

I've given you ample information to correct your misconceptions regarding classical mechanics generally and collapse mechanics specifically. You've rejected it. Nothing more I can do.

I have yet to see one, all I see is empty pedantry based on malicious misinterpretations of everything anybody says who isn't in the IN group.

I am not trying to please you and I am not your student.

You claim to "correct me", yet I can bring up a vast list by now of occasions where the unbelievably obtuse misreadings have resulted in vacuous pages filled with useless banter.

Why do I have to justify logic =/= math.
Prove to you with some lame-ass test that I understand the mechanics involved
Demonstrate that energy, information and force are isomorphic with 1/entropy for the purposes of MY discussion.
Minkowski/Mankowski, why do I need to explain the difference between space and dimension.
That concrete doesn't start falling apart with age spontaneously.
That logical precedence is not the same as chronological precedence.
That NET force is not the same as FORCE.
That PE is zero when a building is at rest and is expected to remain at rest.
That just because the path of least resistance is through air that the building cannot JUMP sideways.
Apologize for claiming that if there is more energy required to effect a collapse than is present in the equations some energy must have been double counted.
...

Really, this is juvenile bickering of the highest order.

I think it is time that I demand an apology here. You have insulted me enough.

by **OneWhiteEye** » Thu May 06, 2010 7:12 am

Prove to you with some lame-ass test that I understand the mechanics involved.

You've proven time and again you don't have a grasp of high school physical science, let alone a grasp of the physics and engineering concepts relevant to study in this field. This, coupled with your haughty attitude, counterproductive interjection of falsehoods proclaimed with the highest confidence combine to make you a big annoyance.

That concrete doesn't start falling apart with age spontaneously.

Roman concrete doesn't, true.

That PE is zero when a building is at rest and is expected to remain at rest.

Absolute rubbish. PE has nothing whatever to do with whether a building is at rest or 'expected' to do anything. Here's a lame-ass (and I mean that most sincerely) test:

What is the one condition under which the calculated potential energy of a building of finite mass in a non-zero gravitational potential is zero?

Apologize for claiming that if there is more energy required to effect a collapse than is present in the equations some energy must have been double counted.

That accusation is false, offensive, unsupported and frankly stupid when made by someone who did not even know the particulars of the model they criticized. You refused to apologize or retract.

Really, this is juvenile bickering of the highest order.

No, this is people becoming increasingly annoyed at your attempts to correct when you don't know what you're talking about. You're in way over your head yet delivering lectures on the subject. It's embarrassing.

I think it is time that I demand an apology here.

You can wait like I'm waiting.

by **Darkwing** » Thu May 06, 2010 7:16 am

Go read my very first post. I admitted weakness and have not stopped being attacked since.

That enough. I believe I have amply proven my claims.

This forum has nothing to add to the debate.

by **OneWhiteEye** » Thu May 06, 2010 7:33 am

Thank you for your opinion. Mine is: you have nothing to add to this forum, except counterproductive disruption.

Feel free to step off at any time, if it's such a drag.

by **OneWhiteEye** » Thu May 06, 2010 7:43 am

Darkwing wrote:I admitted weakness and have not stopped being attacked since.

For the benefit of anyone unable to evaluate who is correct, I offer the following concerning someone who maintains they both do and do not understand the principles involved, according to convenience:

1) Consistent false claims offered without support and in defiance of common physics
2) Typical refusal to accept correction or admit error
3) Ongoing criticism of just about every activity that's taken place here
4) Lectures, consisting largely of the misunderstandings of (1), delivered to those who actually are conversant in the subject

What else can I say? It's a rough deal when you pull your sword out of its scabbard several times a day and poke it in the direction of people who can run you through with their eyes closed.

Enough is enough.

by **Major_Tom** » Thu May 06, 2010 2:23 pm

I admitted weakness and have not stopped being attacked since.

It is unfair to the rest of us for you to be allowed to repeat "that PE is zero when a building is at rest and is expected to remain at rest" on this forum as if you are talking down to the rest of us.

It is such a fundamental mistake that I don't see the point of trying to explain to you how absurd the claim is. For the rest of the readers, if we define

PE= V(x, y, z) in cartesian coordinates, you derive a force field by

F =-gradient(V) where bold means vector. The gradient operator is known to anyone who is familiar with a little vector calculus.

Note that the potential V(x, y, z) gives the same force field as V(x, y, z) + C where C can be any constant.

This means the numerical value of V has no absolute meaning since -gradient(V) is the same for all constants C.

When I read people claim that PE = 0 for a tower (relative to what? No reference point? No derivation?) it shows they have no real practical experience using PE as a tool to derive equations of motion. It also shows they haven't really studied classical mechanics and have no idea how to manipulate equations of physics at a basic level.

How is gravitational PE derived for an object on the surface of the earth?

PE = the sum of mgh for all pieces of mass for the object, where h is the height from a reference point that you define. You can choose any reference point you want. This means that the actual values of V vary depending on which arbitrary reference point you choose. A point on the surface of the earth is a good choice but not the only one.

How can darkwing or anyone claim PE= 0 for an object without mentioning what reference point they are using to calculate it? PE = 0 relative to what point?

PE for more complex mass distribution is derived by summing or integrating the quantity mgh over all the pieces of mass. Such mass is described by a mass density function which I'll call D(x, y, z)

PE is the integral of D(x, y, z)*g*h*dx*dy*dz summed over all space. if we use the surface of the earth for our reference point and define a coordinate system where z=0 on the surface of the earth, then

PE = integral of D(x, y, z)*g*z*dx*dy*dz summed over the entire object.

>>>>>>>>>>>>>>>>>>

It is unfair that people can make claims about PE in this forum while showing no derivation and no proof. We need a new rule which prevents this from happening over and over again.

by **OneWhiteEye** » Thu May 06, 2010 4:46 pm

Excellent post, Major_Tom. It should be the standard reference every time this issue comes up.

The post does a beautiful job of explaining why the recurring claim of "the PE of the tower is zero" marks someone who is of rank below physics "noob". A noobie does not need to know the details given to successfully work with PE in calculations, but whenever they get to the point of asking why, this is the treatment which answers that question. To deny it for lack of understanding only invalidates the person rejecting it, not the explanation.

When someone not only makes an absurd claim, but rejects or ignores correction and continues to make the claim, they demonstrate entrenched ignorance. They've proven beyond shadow of doubt they are unqualified to comment on any aspect of the physics of collapse, forget about critiquing peer-reviewed scientific literature. Invariably, it is accompanied by sweeping unsupported claims of proof of nonsense and/or falsification of standard theories.

This has happened more than once. When it happens, it's attacked and justifiably so. No need to make excuses against passive-aggressive accusations of groupthink for shooting BS down at its source. Not on a scientific forum. If those who know better let BS stand, it reflects poorly on the forum by giving the indication there's no one who objects and stupid rules the day here. If someone takes time, every time, to set the record straight, their time is being squandered by morons who fancy themselves illuminators. Without fail, these attempts to put the discussion on firm scientific footing are rejected and mocked further, even leading to cries of "juvenile bickering" by the offender.

When the moderator fails to eliminate such distractions on the basis that it appears biased or heavy-handed to silence what is actually disruptive poppycock, the squandering is allowed to continue unabated and the forum content suffers both by filling up with chaff and by diminishing the time spent on quality work. Not to mention high blood pressure. I've tried repeatedly to state for the record that the forum cannot tolerate this disruption, but the existing offenders ignore it and the newcomers add to the pile without even showing the consideration to know the arguments they dismiss.

For the sake of a few members having open minds but unable to differentiate between a good physics argument and a bad one, it's time you know that these disputes can no longer be settled in this manner. If it seems like censorship to blow these ill-formed arguments out to the discard area without even a word (but with a warning), well, too bad. This is not a debate on equal footing. The damage done is asymmetrical, affecting those who are correct and have significant investment in the forum much more than those who breeze in and stir the pot with pseudoscience.

Consider this notice that the inequitable consequences have been tolerated long enough. Sincere questions and desire to learn are always encouraged. Strident pseudoscience never has been. If you think I'm harsh, you should see how Greg deals with this stuff. It will no longer be tolerated.

by **psikeyhackr** » Thu May 13, 2010 4:21 pm

How can darkwing or anyone claim PE= 0 for an object without mentioning what reference point they are using to calculate it? PE = 0 relative to what point?

If the distance between the two points is full of mass that cannot be moved then what is the point of the mathematical calculation?

You can do a mathematical calculation for the top 100 feet of Mt. Everest relative to sea level if you want to. What would it be besides a mathematical delusion? Is anybody going to wait around for it to fall?

Plenty of people try to use mathematics to show how smart they are but physics ain't mathematics and is incapable of giving a damn about mathematics. The core columns in the WTC could not fall because they had other core columns below them which also could not fall all of the way down to bedrock.

If someone wanted to they could calculate the so called Potential Energy of the top 100 feet of bedrock all of the way to the center of the Earth. It would be nothing but mathematical pseudo-intellectual bullshit. The potential energy of the WTC was zero because the structure would have to be changed to create a weakness or emptiness for mass to fall into.

Now supposedly that happened because of the plane and fire. But the PE height calculation would only be for the space created not all of the way to the ground. If you watch the videos of the top of the south tower turning into dust hundreds of feet above the ground how could a potential energy calculation all of the way to the ground have anyting to do with that?

If you use a helicopter to lift a 10 ton block of concrete 1000 feet then the potential energy can be calculated. If the block is dropped it is not going to turn to dust after falling 200 feet. It will remain perfectly intact until it hits the ground. So how did the supposed PE of the WTC produce dust hundreds of feet above the ground?

psik

by **OneWhiteEye** » Thu May 13, 2010 6:01 pm

psikeyhackr, why oh why did you have to get back to this before we completed the discussion of failure energy in the Crush Models thread? I really believe you could come to understand this concept via the back door with a discussion of failure. But, since you brought it up now, I'm going to do what I said I would the next time someone brought it up:

OneWhiteEye wrote:Future incidents of unbridled pseudoscience will be directed to this announcement and may be followed with warning at moderator discretion. Threads may be split to the discard area without explanation other than linking to this announcement.

http://the911forum.freeforums.org/leave-the-pseudoscience-at-the-door-please-t365.html

That announcement references Major_Tom's post above. This brings around full circle to here. After all the times and ways trying to explain this very simple idea, there is still no progress and yet I'm going to try one more time.

Potential energy is just that, it's not counted UNTIL it's lost. When a mass loses elevation in a gravitational field, it loses potential energy. If there's something holding it up, it doesn't lose elevation and therefore doesn't lose potential energy. Doesn't matter why it would lose elevation, it only matters that it does or not. If the Balzac-Vitry had instead been laced with thousands of charges to destroy all structural integrity in advance of the upper block, the change in total PE would be the same as it was. Intact building / Rubble pile. Initial PE / Final PE.

If the distance between the two points is full of mass that cannot be moved then what is the point of the mathematical calculation?

"...full of mass..."

The example you gave, Mt. Everest, is indeed full of well-compacted mass. The towers, even including office contents, were not full of mass and that is a crucial difference but still not the deciding factor in collapse. If Mt. Everest were to be sectioned to the same freestanding aspect ratio as a tower, I'm not sure how long it would take to collapse, but it would eventually. No, upper would not fall through lower, it's full of mass!!!

"...that cannot be moved... "

Unlike Mt. Everest, the towers were mostly air. If any level does fail, by assistance or otherwise, it no longer supports the load above and the load moves down, by definition. Whether it drops straight down or tips depends on the degree of uniformity of the failure across the footprint, but it will lose elevation in either case and therefore lose PE. How far and how fast depends on what the supporting force is, but it's defined to be less than the weight at the time of failure. The amount of potential energy loss depends only on the distance dropped and is the same no matter whether it drops slowly (slow failure near mg capacity) or in freefall (all capacity lost suddenly).

PE comes into calculations because, when a block has dropped, it has lost PE. Before then, it's only potential energy, hence the name. Once some of it lost, it must be accounted for! Force dictates whether the block remains static or drops and what the instantaneous acceleration (therefore v and y) is over time. Energy is not force, but the two are related: work (energy) is force applied through a distance. Potential energy is the source for the work done in crushing because the force derived from gravitional potential is weight!

If there is no failure (i.e., defect) there will be no motion, no PE loss. If there is a fail and downward movement occurs, there will be PE loss. Small displacement, small PE loss.

Capacity always greater than load
=> No motion -> no PE change -> no energy for work available -> no crushing

Capacity less than load at any point
=> some motion -> some PE change -> some energy available for work -> some crushing

Capacity always zero
=> free fall motion -> PE change (at maximal time rate - power) -> tons of energy available to do work
- and yet -
=> no work done in crushing

Your simulator is stuck in the last context, with magic supports added otherwise it would be simultaneous freefall of all floors. By this magic, you can invoke the inelastic collisions that also have to take place but it still leaves no resistive force due to supports, which take energy to fail.

I felt you'd finally come around on the PE thing once understanding how fail energy is incorporated into your simulation. You're doing F=ma and F is currently only mg so g = a. You want to include a force that's derived from the energy dissipated in failure of supports, and this force acts in opposition to gravity to slow the descent. You already have the dreaded PE loss implicit (force due to gravity) in your equation of motion, but don't know it! Major_Tom explained it above. You need a force derived from energy to counteract the force derived from loss of PE!

Do you see the irony?

psikeyhackr, we've been having this nice conversation in the Crush Model thread. I've been preparing some stupid pictures to help explain how to incorporate a resistive force into your simulator. I'm going to post over there when I have time. Can you trust me until then that the way PE enters the mechanics is quite sound? You're already doing it, that plus momentum is all you're doing, there's nothing wrong with it except you want it to be more realistic by adding some resistance. You don't realize that you're complaining that your simulation incorrectly calculates freefall between collisions! That's what all this is about...

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