We previously saw a Fox News pie chart that had a couple extra slices (here). Now, fair and balanced math adds up to 120 percent of voters indicating that they view the science on global warming to be rigged.
This is an interesting Rasmussen poll when you add up the number and discover that you are in a parallel universe.
The question is: “In order to support their own theories and beliefs about global warming, how likely is it that some scientists have falsified research data?” According to the poll, 35 percent thought it very likely, 24 percent somewhat likely, 21 percent not very likely, and 5 percent not likely at all (15 percent weren’t sure).
This rather dubious poll is offered to show that people are dubious about the science and math of global warming experts.
For the full story, click here
Buddha is Laughing,
“Again, where do you plan to stop your infinite regression?”
Infinite regression is reality. Sound, friction, shock waves, heat all play into this infinite regression. Look at the Second Law of Thermodynamics. http://www.ftexploring.com/energy/2nd_Law.html
As you can see, in the real world energy cannot be considered to be conserved.
Slartibartfast,
Read this real slowly: The law of conservation of energy is an empirical law of physics. It states that the total amount of energy in an isolated system remains constant over time (is said to be conserved over time).
No isolated system, no conservation of energy. An isolated system does not interact with the environment.
How much work (energy expended) is required to break a floor of the WTC loose? If a single floor breaks loose, and lands on the floor below it, but that floor does not give way; the floor is no longer at the same height, so the PE has decreased. Where is the energy now? (please accept that the energy was transmitted into the environment and for all purposes it must be considered to be lost (non recoverable) (not conserved for later application)
Bob,
Will do. If you don’t still have my proper gmail address, use my new blind @ buddha.is.laughing.ril@gmail.com.
Robert,
You’re still wrong about isolated systems as related to analysis of conservation. Again, where do you plan to stop your infinite regression? No one is arguing there is such a thing as a closed system in nature (unless you count this entire membrane as a closed system and even it isn’t closed within the context of M-theory). But the contention is that looking at conservation without using defining an isolated system as a limiter is a formally flawed analysis. You still haven’t explained why a property of all the visible universe doesn’t apply to an isolated or evan an open system covering a small segment of NYC real estate. You’ve ignored it quite well, but you haven’t addressed that point. If you don’t like the artifice math requires for us to make analyzing conservation questions, you’ll need a better alternative than “it doesn’t apply because I don’t like isolated systems”. You disliking a tool and a tool’s utility/function are different things. I think friction is a drag. Doesn’t mean it isn’t real. It’s also looked at an isolated system but just not in a formal way like isolation is applied to conservation. If you look beyond air friction and drag relative to local resistance related phenomena (air density, etc.), you’re no longer looking at a friction problem. Your data set has moved to the tangential and is defeating the purpose of analysis in the first place. You must know when to stop analysis. Too much data past a point is counter productive to getting answers. Until you address the infinite regression problem with analyzing conservation without isolation, you’re falling into a rabbit hole that ends with the nature of spacetime/reality. Without isolated systems, every conservation problem comes down to the tensile strength of local spacetime – are energy and matter in balance as physical properties of the membrane. You don’t need to go that far unless your contention is that the 9/11 criminals some how have developed a bomb or impact scenario capable of rupturing spacetime. You only need to be concerned with 1) the buildings, 2) their stored energy, 3) the planes and 4) their potential energy. That’s the system in isolation. If you look “further down” than that? You are not only misapplying conservation analysis, but wasting your time as well. The analysis of conservation as related to the WTC collapse need not be made with absolute precision and as a matter of fact cannot be known with absolute precision. But leaving infinities in the analysis will not help move toward even reasonable precision much less absolute precision.
“System identification
The process of determining the equations that govern the model’s dynamics is called system identification. This can be done off-line: for example, executing a series of measures from which to calculate an approximated mathematical model, typically its transfer function or matrix. Such identification from the output, however, cannot take account of unobservable dynamics. Sometimes the model is built directly starting from known physical equations: for example, in the case of a mass-spring-damper system we know that . Even assuming that a “complete” model is used in designing the controller, all the parameters included in these equations (called “nominal parameters”) are never known with absolute precision; the control system will have to behave correctly even when connected to physical system with true parameter values away from nominal.”
Look into control theory.
You’re wrong about isolated systems and their utility.
http://en.wikipedia.org/wiki/Control_theory
You seem to want absolute precision here, Robert. That’s not going to happen. Nature won’t allow it.
Slart,
Nah I meant the standby “What would convince you?” test. The danger in that tactic is it switches the burden of proof. However since you just spent the past few days giving a refresher course on physics 201, I think the burden already got switched early in the conversation. Bob’s a brilliant debater, and while you are schooling him on actual science and math, he wins for style. His greatest strength comes in never acknowledging that simply pointing out errors in others arguments in no way proves he’s correct. That’s why the obsession over a bad analogy on your part. That’s why the nit picking over what you’ve already admitted are generalizations without any attempt to prove that they would effect the equations enough to reduce your hundreds of billions of Jules enough to remove the ability to reach the threshold for melting steel.
Bob,
So how about it, what would convince you?
Bob posted:
“Robert: “You fail to account for how the floors were broke loose. You don’t account for any of the energy used to trun the concrete into rubble.
If you use energy to break the floors loose, you can’t also include it as kinetic energy. If you use energy to turn the cement into rubble, you can’t include it as kinetic energy involved with the impact.”
You do understand that this has been my complaint all along; right?”
I have said repeatedly that 17.4% of the gravitation potential energy of the WTC went into breaking the structure of the building and pulverizing the rubble. Since energy is neither created or destroyed, a good portion of this energy ends up where most (all?) energy ultimately ends up (in accordance with the 2nd law of thermodynamics) as randomized motion of particles – i.e. heat. However, I have repeatedly said that I DID NOT INCLUDE THIS ENERGY IN MY CALCULATION OF THE HEAT GENERATED! In other words, you have no legitimate complaint here, since even if your argument was correct (which it is not since it violates conservation of energy, which is a pretty serious flaw in a physics argument), it’s still irrelevant since I excluded this energy from my heat calculation.
Bob said:
“Energy, by definition, is the capacity of an object for doing work; normally measured in joules.
A joule is the amount of work done by a force of one newton moving an object through a distance of one meter.
1 Newton = 1 kg m/s^2
1 Joule = 1 kg m/s^2 x 1m or 1 kg m^2/s^2
If the majority of the potential energy of an object (Oh, say the WTC Towers) is used in the creation of Work, (Force and movement in the direction of said force), i.e. that which is (allegedly) shredding the building, it cannot ALSO be counted as pure kinetic energy. Assuming a pure unassisted collapse, whatever PE wasn’t converted into work to break apart the Towers exists as a small remainder of Ke following the path of work on the way down.”
By what argument do you claim that the ‘majority’ of the potential energy went into shredding the building? There was clearly an enormous amount of kinetic energy present in the rubble before it slammed into the ground (in many inelastic collisions). By estimating the speed of collapse vs. free fall, I was able to calculate that 82.6% of the gravitational potential energy was present in the form of kinetic energy, leaving 17.4% of the gravitational potential energy (100,000,000,000 joules) for destroying the structure of the building. These percentages change if you change the collapse time vs. free fall time, but the calculation is correct. In science, we don’t get to say things that we can’t back up with evidence of one sort or another (well, we can say things, but no one gives them credibility). It is indisputable that there was something like 1,000,000,000,000 joules of GPE stored in the towers. It is indisputable that the falling debris contained kinetic energy. It is indisputable that the rubble pile did not contain this kinetic energy. It is indisputable that this energy was not destroyed. You don’t have to take my word for any of these things, this is what physics says – contradict them and you loose all scientific credibility. I have done a calculation (which I clearly laid out) to estimate what portion of the GPE went into KE in the descending rubble pile and what portion of the GPE went into to destroying the building as it fell (I found that this was roughly the same energy found in 24 metric tons of TNT – are you saying the 24 metric tons of TNT are not enough to bring the building down? Are you saying that tons of explosives were covertly placed in the towers?) Show me the calculation that justifies that the majority of potential energy went into destroying the building. Make an argument as to why this required more than 24 metric tons of TNT. But just realize that this is a trade-off, the closer to free-fall speed the building fell, the more of the original GPE was kinetic energy in the descending rubble. (If the building fell at free fall speed all of the GPE would have been present as KE.)
Bob said:
“Finally Robert, there is no ‘impact’ event; the analogy is false. A building existing on earth and collapsing on earth is not said to ‘impact’ the earth — because you can’t GET THERE from here. And with the building being on earth, you sure as shit can’t raise the velocity component of Ke, for any debris not involved in the work of tearing the building apart, any higher than terminal velocity will allow–thus making the meteor analogy completely inapplicable.”
I’m assuming you meant Slart, not Robert. Terminal velocity is when the force of atmospheric drag (friction) is balances the force of gravity and a falling body stops accelerating. It is not in play in ANY of the situations we’ve been discussing. I’ll discuss why I can treat the WTC collapse the same way as a meteor in my response to Buddha’s post.
In my lighter analogy, I should have stated that the butane lighter flame is measured in degrees C.
Bob,
I am in complete agreement with you. Don’t read more into the word “impact” than its definition. It refers to the collision of two objects.
The major flaw in Slarti’s conclusion is that he considers this to be an isolated system, which causes his calculations to ignore all interactions with the environment (interaction with the environment is scientifically impossible in an isolated system). The pulverizing of cement into rubble expends a lot of energy in the form of work. The ejection of metal girders 600 ft expends a lot of energy in the form of work.
Heat (what we measure as temperature) is thermal energy in transfer. Friction is a very inefficient method of energy transfer. In an open system, most of that energy is transferred to the atmosphere.
Another major flaw is the complete disregard for impact angle. What are the chances that most of the falling material hit the material at the bottom (earth and rubble) at a 90 degree angle (the angle most efficient for energy transfer), and why/how did it convert to thermal energy? Why didn’t it perform work by moving earth or rubble? Slarti assumes that all of it hit at a 90 degree angle, and most of the energy was retained in the rubble instead of being dispersed into the surrounding earth. The majority of energy left in the falling material was transferred into the earth. Early realization that this is not an isolated system would have made that easier to acknowledge.
Heat does not transfer instantaneously. The rate of heat transfer is directly related to the specific heat transfer coefficient of the material. i.e. a butane lighter burns at approximately 2000 degrees. Yet, you can pass your finger thru the flame without getting burnt.
Buddha,
There were a few posts of yours I’ve been meaning to address, but I got caught up as you can see.
Keep an eye on your email.
Slartibartfast: “All three events are inelastic collisions, I used the physics of inelastic collisions to perform my calculations. That being said, do you concede the point on the bullet? I’ll defend my assumptions about the WTC collapse below. I am assuming the that the collapse was ‘natural’ (as was the assumption in my analysis).”
A (high velocity) bullet impact is not comparable to a building collapse. As I stated above just a few minutes ago “there is no ‘impact’ event; the analogy is false. A building existing on earth and collapsing on earth is not said to ‘impact’ the earth — because you can’t GET THERE from here. And with the building being on earth, you sure as shit can’t raise the velocity component of Ke, for any debris not involved in the work of tearing the building apart, any higher than terminal velocity will allow–thus making the meteor analogy completely inapplicable.”
Slartibartfast: “The collapse started at the impact zone and proceeded downward.”
So you say; however there are eyewitness accounts of civilians, cops, firemen AS WELL AS VIDEO AND AUDIO FOOTAGE providing clear and convincing evidence of massive explosions within the Towers before they fell.
Slartibartfast: “Imagine a surface above which the structure had begun to fail and below which the structure is still intact. Define the speed of this surface as the speed of collapse. I estimated that speed by using 6.6 seconds (and constant acceleration) for the collapse and 6 seconds for free fall. Above this surface is a mass of debris descending at the speed of collapse (remember, the portion of the building above the impact zone acted as a giant piston, pulverizing the building into debris and accelerating it*).”
That is your theory, it’s not a point of fact; but continue.
Slartibartfast: “Call the time that this surface passed ground level t0.”
What are you saying; that the basements had enough empty space to accommodate all the debris? Because that’s not true.
Slartibartfast: Now, a moment before t0, there are debris with the mass of the building moving at the speed of collapse. A short time later, there is a pile of debris that is stationary, having undergone an inelastic (non-bouncy) collision with the Earth. Using this model, I calculated the kinetic energy which existed before t0 and didn’t exist (because it had primarily been changed into thermal energy) a short time after t0.”
Here are just a few problems with this theory already. First, by what mechanism are you allowing for the possibility of a building to fall at free fall speed, for your alleged six seconds, through the path of greatest resistence; i.e. the structure of the building itself? IOW, your hypothetical demands the assumption that everything that the architects, engineers and construction workers put in place to support the building on its way up has completely VANISHED during your scenario. Further, as Buddha is so keen to point out, a free fall collapse, beginning with asymmetrical damage, like the one you’re suggesting, necessitates some form of magic in the form of a spontaneous symmetrical removal of all previous support structure BEFORE your falling debris reached each successive level of support. IOW, the path of greatest resistance, i.e. each level of the structure holding up the building, must magically disappear before the object in your inelastic collision scenario reaches it; otherwise the resistance would preclude free fall speed. This scenario also necessitates an architecture more simplistic than a child stacking boxes.
Slartibartfast: “Now I make several simplifying assumptions – that the impact takes place when the surface of collapse reaches ground level, that the ground is a solid plane (no basements, etc), that the rubble doesn’t pile up (leaving remaining gravitational potential energy), that the building collapses into its own footprint, and so on**.”
Sine I am making an incredible effort at suspending disbelief for all the impossible premises which your theory relies upon — if only to fully comprehend what you’re saying; may I ask how the hell you can make some ‘simplifying’ assumptions when you in fact know they are wrong? For instance, how do you give yourself license to assume the rubble is not piling up? That’s part of the reason your theory fails; seeing it’s the result of increased resistance slowing down the collapse and expending the PE in the form of work to create said rubble.
Slartibartfast: “In science, in order to deal with complex systems, these sorts of simplifying assumptions are necessary.”
No, that type of simplifying assumption is an attempt to justify jury rigging to arrive at your pre-determined outcome. “A man’s got to know his limitations” and your sweeping generalization about science does not give you license to ignore facts that preclude your theory of being true.
Slartibartfast: “In my judgement*** the assumptions that are made are reasonable for the analysis I did. This sort of ‘back of the envelope’ calculation is not to precisely determine the quantities involved, but instead get an idea of the general size of the forces involved.”
The main force involved here has to do with PE being converted to WORK; i.e. the Work required to direct Newtons against Newtons of resistance, i.e. the Newtons pushing back against the Work in the form of the structure, design & material, which you implicitly claim do not exist for purposes of your hypothetical.
Slartibartfast: “This analysis implying that enough heat was created to liquify 500 metric tons of iron suggests to me that molten iron would be expected at ground zero.”
Sure there’s plenty of energy to go around; especially if your hypothetical is getting its work for free and converting Ke to heat energy by ignoring the factual scenario of the building design and purpose itself and without so much as hinting at a plausible mechanism of converting said Ke into heat for the event. No matter how much you may hypothesize, there is no component of the collapse containing a velocity component of the magnitude you need to make your meteor analogy stick–i.e. none of the steel is moving so fast as to collapse on itself and create the type of heat created by a meteor impact; and which you claim a bullet traveling at 1/11th the velocity does as well.
Slartibartfast: “Given that there was additional heat from fires (observed) and exothermic reactions (the reaction I suggested between hot iron and steam is highly likely),”
As reported from the fire fighters by radio just before they were crushed to death, the fires were essential out. Furthermore, these ‘exothermic reactions’ you talk about are not ‘given’ — they are the subject of discussion–especially in light the evidence of active thermitic material found in the dust of ground zero.
http://www.globalresearch.ca/index.php?context=va&aid=13049
Slartibartfast: “it seems reasonable to expect that high temperatures would persist for quite a while in the rubble.”
Predicating that which has not been established is tantamount to predicating non-existence. By begging the question of the creation of heat energy from kinetic energy sans the conversion step, I ask yet again where are you getting your steam, hot iron from? “‘Exothermic reactions in the rubble’ — like the kind you get from thermate — evidenced in the dust found in the rubble of the WTC?” (See my previous objection to this leap in logic above.)
Slartibartfast: “**If we look at an individual piece of rubble, it’s moving at somewhere near the speed of collapse and at some point has an inelastic collision with the earth. My simplifying assumptions enable me to estimate what we get when we add the effect of this collision for each piece of rubble.”
No, it ignores the loss of energy when Pe is converted to the Work required to CREATE the rubble. (See my reply to Robert earlier today)
Slartibartfast: “***When I say my judgement, I mean my professional judgment. My research involves making assumptions to simplify complex systems in order to create useful models.”
I am not questioning your professional ability or scientific acumen in general, I’m simply saying your haste in making your argument here is blinding you to some basic axioms, that cannot be overcome by any assumptions.
Slartibartfast: “What you describe is one way in which the kinetic energy of the impactor is being transformed into thermal energy. It accounts or a very small fraction of the total kinetic energy of the impactor prior to impact (my guess is that it is less (possibly significantly less) than the 17.4% lost in my analysis of the WTC collapse).”
There’s no impact, there’s no high velocity component and you’re ignoring the Work factor.
Slartibartfast: I admit that I may have taken a disrespectful tone in this discussion and for that, I apologize.”
You can take any fucking tone you like; I’ll still be looking for the sound argument no matter what. And what’s wrong with a little spice in life?
Slartibartfast: “But please acknowledge that I’m not making this stuff up, and give me a little respect, too.”
If I didn’t respect you I wouldn’t fucking bother arguing with you. Remember what I said earlier about my lack of respect for the Birthers?
Slartibartfast: Your arguments have been cogent and well-articulated and although I also believe that they show some fundamental misunderstandings of physics, they have forced me to go back to something I had looked at years ago and prove to myself that the educated guess I had made then was correct.”
Careful; when you wake up and smell the Work you’ve been sweeping under the rug, you’ll have second thoughts about my misunderstanding of physics.
Slartibartfast: “Before this discussion I had faith that I was correct, now I am certain of it. For that, I sincerely thank you.”
If you’re certain you’re correct, then Socrates says you’ve put yourself outside the purview of meaningful argumentation.
Slarti/Robert:
“The energy required to change steel from solid to liquid is called the heat
of fusion and it’s about 272,000 joules per kilogram. (5)”
I read that wrong, Robert is right. I did my own calc and came up with about 683,000 joules to totally melt 1 kg steel from room temperature.
Got to go with Bob on that one. Astronomical impact events are a totally different creature than a building collapse. For one, you are talking about differences in KE that are off by huge orders of magnitude even if you discount the differences that would occur due to angular momentum. Asteroids and comets move A LOT faster than planes do. There is also the disparity in average mass issue. Many meteors are small. Some are as big as mountains. Some are as big as states. Big ones. Not Rhode Island. That makes it apples and oranges too. Had they flown the jets in a parabolic arc and dropped into the towers nose to roof or at a steeper angle? It might be a more appropriate analogy but even then it wouldn’t be exact or particularly helpful since even the Vomit Comet maneuver wouldn’t impart enough KE to makes those differences in scale negligible.
Robert: “You fail to account for how the floors were broke loose. You don’t account for any of the energy used to trun the concrete into rubble.
If you use energy to break the floors loose, you can’t also include it as kinetic energy. If you use energy to turn the cement into rubble, you can’t include it as kinetic energy involved with the impact.”
You do understand that this has been my complaint all along; right?
Energy, by definition, is the capacity of an object for doing work; normally measured in joules.
A joule is the amount of work done by a force of one newton moving an object through a distance of one meter.
1 Newton = 1 kg m/s^2
1 Joule = 1 kg m/s^2 x 1m or 1 kg m^2/s^2
If the majority of the potential energy of an object (Oh, say the WTC Towers) is used in the creation of Work, (Force and movement in the direction of said force), i.e. that which is (allegedly) shredding the building, it cannot ALSO be counted as pure kinetic energy. Assuming a pure unassisted collapse, whatever PE wasn’t converted into work to break apart the Towers exists as a small remainder of Ke following the path of work on the way down.
Finally Robert, there is no ‘impact’ event; the analogy is false. A building existing on earth and collapsing on earth is not said to ‘impact’ the earth — because you can’t GET THERE from here. And with the building being on earth, you sure as shit can’t raise the velocity component of Ke, for any debris not involved in the work of tearing the building apart, any higher than terminal velocity will allow–thus making the meteor analogy completely inapplicable.
[youtube=http://www.youtube.com/watch?v=ssuAMNas1us&hl=en_US&fs=1&]
[youtube=http://www.youtube.com/watch?v=xpYz1XXe6Hk&hl=en_US&fs=1&]
[youtube=http://www.youtube.com/watch?v=3FVJX79ohyU&hl=en_US&fs=1&]
Robert,
My response to Bob answered some of your questions, hopefully this will clear up the rest.
You said:
“Arrogance is the downfall of many a scientist.”
And it may be mine, but I’m right this time. 😉
You said:
“Was this energy directed at a 1″ x 1 ” area, or was the area of impact 500 sq. miles? You don’t say.”
I would assume that this energy was spread out over the 300 to 400 meters that the debris fell, fairly heavily concentrated in the footprint of the building. If the energy were spread out over just the footprint of the building, it would result in an energy density of over 10,000 joules/cm^2. I would take this as a very rough estimate of the energy density at the center of the footprint.
You said:
“According to your theory, if I used a crane to put every piece of the WTC on the ground, the crane would either burst into flames from doing so, or the pieces on the ground would melt steel simply because they had the potential for doing so at some point in time.”
No. The gravitational potential energy would be converted into other forms of energy slowly and harmlessly (well, some additional wear and tear on the crane).
You said:
“This is not an isolated system. By treating it as one, you completely forget about any work performed. You fail to account for how the floors were broke loose. You don’t account for any of the energy used to trun the concrete into rubble.”
I calculated that 17.4% of the original gravitational potential energy went into collapsing and pulverizing the building. Some of this energy left the system via particles in the pyroclastic flow. The rest of it remained in the debris as heat (I didn’t include this energy in my analysis – effectively assuming that all of this energy left in the pyroclastic flow). Consider an imaginary box that completely contains the WTC (from the subbasement to the tip of the radio masts). Initially, this box contains approximately one trillion joules of gravitational potential energy. All of this energy either remains in the box or is transferred out of the box – I have kept track of the energy that stayed in the box and estimated that enough of it was converted into heat to liquify approximately 1,000 metric tons of iron at room temperature. I have not in any way violated the law of conservation of energy.
You said:
“If you use energy to break the floors loose, you can’t also include it as kinetic energy. If you use energy to turn the cement into rubble, you can’t include it as kinetic energy involved with the impact. In an open system, energy expended must be considered lost energy.”
I didn’t include it. Although a portion of the kinetic energy used to break the floors loose ultimately remains in the rubble as heat, since there’s no way to quantify this portion (which didn’t leave via pyroclastic flow or other mechanism) I excluded it all. I have very carefully and clearly explained my process, please don’t accuse me of doing something that I explicitly indicated that I did not do.
Gyges,
Feel free to butt in, but that’s sort of what I thought I was doing. I explained myself as clearly and completely as possible and stated exactly what my position was and why. I apologized for the tone I had taken in the discussion. I promised to reveal my identity (something I had been thinking about for a while). Bob will reply how he wants. The rest of you can judge the two of us based on our words. I’m content with that.
Slart,
Not to butt in, but perhaps it is time for the old “skeptic vs denier” test be applied to Bob.
Bob posted:
“Slartibartfast: “The laws of physics operate independent of scale.”
I don’t object to your use of scale, I object to your comparison of events.”
All three events are inelastic collisions, I used the physics of inelastic collisions to perform my calculations. That being said, do you concede the point on the bullet? I’ll defend my assumptions about the WTC collapse below. I am assuming the that the collapse was ‘natural’ (as was the assumption in my analysis).
Bob posted:
Slartibartfast: “So how much kinetic energy was in the rubble the instant before impact?”
Instant before impact?? WTF are you talking about? A structure at rest on planet earth which thence collapses is not said to have ‘IMPACTED’ the earth. It’s already ON EARTH and the collapse is a decay of its previous higher ordered structure. Without getting into the Ship of Theseus puzzle, suffice to say that parts of the building impacting the earth does not mean the building impacted earth.”
(I had to look up the ‘Ship of Theseus puzzle’. Nice reference, let’s just stick to the physics.)
The collapse started at the impact zone and proceeded downward. Imagine a surface above which the structure had begun to fail and below which the structure is still intact. Define the speed of this surface as the speed of collapse. I estimated that speed by using 6.6 seconds (and constant acceleration) for the collapse and 6 seconds for free fall. Above this surface is a mass of debris descending at the speed of collapse (remember, the portion of the building above the impact zone acted as a giant piston, pulverizing the building into debris and accelerating it*). Call the time that this surface passed ground level t0. Now, a moment before t0, there are debris with the mass of the building moving at the speed of collapse. A short time later, there is a pile of debris that is stationary, having undergone an inelastic (non-bouncy) collision with the Earth. Using this model, I calculated the kinetic energy which existed before t0 and didn’t exist (because it had primarily been changed into thermal energy) a short time after t0. Now I make several simplifying assumptions – that the impact takes place when the surface of collapse reaches ground level, that the ground is a solid plane (no basements, etc), that the rubble doesn’t pile up (leaving remaining gravitational potential energy), that the building collapses into its own footprint, and so on**. In science, in order to deal with complex systems, these sorts of simplifying assumptions are necessary. In my judgement*** the assumptions that are made are reasonable for the analysis I did. This sort of ‘back of the envelope’ calculation is not to precisely determine the quantities involved, but instead get an idea of the general size of the forces involved. I wouldn’t be surprised to find my calculation accurate within an order of magnitude or less and I would be surprised if it wasn’t accurate within 2 orders of magnitude. Using this sort of analysis provides a context in which to interpret evidence. This analysis implying that enough heat was created to liquify 500 metric tons of iron suggests to me that molten iron would be expected at ground zero. Given that there was additional heat from fires (observed) and exothermic reactions (the reaction I suggested between hot iron and steam is highly likely), it seems reasonable to expect that high temperatures would persist for quite a while in the rubble.
*The 17.4% drop from the gravitational potential energy to the kinetic energy before impact is the energy that went into pulverizing and accelerating the debris, it remained in the debris as thermal energy. This source of heat is neglected in the analysis.
**If we look at an individual piece of rubble, it’s moving at somewhere near the speed of collapse and at some point has an inelastic collision with the earth. My simplifying assumptions enable me to estimate what we get when we add the effect of this collision for each piece of rubble.
***When I say my judgement, I mean my professional judgment. My research involves making assumptions to simplify complex systems in order to create useful models. I am currently near submitting two research articles for publication. In order to establish my bona fides I will post links to these articles once they are accepted, effectively revealing my identity (I’m the first author on both papers). I’m willing to stand behind what I say.
Bob said:
“The meteor example necessitates a velocity so fucking high that the rear of the meteor, upon IMPACT, is traveling so fucking fast that it compresses against the front of the meteor–i.e. one source of heat from impact.
In what way shape or form does the collapse of a steel building contain that type of event??!!
SHOW ME.
Again,”
What you describe is one way in which the kinetic energy of the impactor is being transformed into thermal energy. It accounts or a very small fraction of the total kinetic energy of the impactor prior to impact (my guess is that it is less (possibly significantly less) than the 17.4% lost in my analysis of the WTC collapse). I have done my best to show you how the countless (actually, a very large but finite number of) inelastic collisions involved in the WTC collapse are a lot of smaller versions of impactors hitting the earth or bullets hitting a metal plate. Again.
I admit that I may have taken a disrespectful tone in this discussion and for that, I apologize. But please acknowledge that I’m not making this stuff up, and give me a little respect, too.
Your arguments have been cogent and well-articulated and although I also believe that they show some fundamental misunderstandings of physics, they have forced me to go back to something I had looked at years ago and prove to myself that the educated guess I had made then was correct. Before this discussion I had faith that I was correct, now I am certain of it. For that, I sincerely thank you.
Buddha,
Yeah. I think the post on the physics of the collapse that I worked on all afternoon was a clue.
Bob,
I’m working on a response to your last post.