How do we know the calculations are correct?
911 physics for dummies
How do we know the calculations are correct?
I don't know either. Google is your friend.
But if an engineering journal doesn't publish letters and articles by engineers simply because those letters and articles may go against the publishers ideology, then there's obviously going to be a market for a new journal which doesn't have such constraints.
Or all the engineers just tow the line too? Ever spoken with one?
Perhaps you might consider the issue of professional indemnity insurance which all structural engineers have to carry, as well as the requirement for professional engineers to engage in what in the UK is known as Continuing Professional Development (CPD) in order for them to maintain their membership of their professional bodies. Engineers have to satisfy both their insurers and their professional bodies that they are up to date and know what they're talking about. I suspect in that climate they are unlikely to subscribe to a technical journal which does not supply them with information which impacts upon their professional knowledge.
Sizzler,
Not my forum, but there's already another thread questioning the collapse physics. I had hoped this wouldn't become another 500-post repeat of that. Any chance you could take the discussion over there? I didn't start this thread to question the basic validity of the "natural collapse" science, or global warming, etc.
Thanks
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sure. movin along.
leftysergeant
Penultimate Amazing
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Not all of the answers even require a knowledge of physics.
As a fire fighter, cook, construction laborer and model buildier, I observed phenomena and handled materials which give me an insight into things that the ivory-tower-dwellers like Jones miss.
Like the resemblance between Jones' "thermite chips" and ordinary paint chips.
Like the resemblance between the "white puffs of smoke" immediately following the start of collapse and crushed wall board.
Like the abscence of the blinding white light which would have to have attended the burning of thermite.
As for the time of the collapse, there are two ways that we can help you straighten that out in your mind.
I first figured that to be BS by watching videos and examining stills of the collapse of the north tower. There are visible pieces of solid matter falling more than half the distance to the ground from the zone of collapse. Since the unattached objects cannot be falling faster than free-fall, and the zone of collapse is falling behind in relation to the free objects, the collapse is occurring at far less than free-fall speed.
RKOwens4, who posts to this forum has posted some very good video on YouTube to explain away many of these points.
Mark Roberts, posting as Gravy, has prepared a very informative 45 minute video on the collapses of the buildings to specificly address some of the issues. I highly recommend that you watch it. I find it useful when twoofers ask me to back up a claim that seems to them counter-intuitive.
Is that helpful at all?
As a fire fighter, cook, construction laborer and model buildier, I observed phenomena and handled materials which give me an insight into things that the ivory-tower-dwellers like Jones miss.
Like the resemblance between Jones' "thermite chips" and ordinary paint chips.
Like the resemblance between the "white puffs of smoke" immediately following the start of collapse and crushed wall board.
Like the abscence of the blinding white light which would have to have attended the burning of thermite.
As for the time of the collapse, there are two ways that we can help you straighten that out in your mind.
I first figured that to be BS by watching videos and examining stills of the collapse of the north tower. There are visible pieces of solid matter falling more than half the distance to the ground from the zone of collapse. Since the unattached objects cannot be falling faster than free-fall, and the zone of collapse is falling behind in relation to the free objects, the collapse is occurring at far less than free-fall speed.
RKOwens4, who posts to this forum has posted some very good video on YouTube to explain away many of these points.
Mark Roberts, posting as Gravy, has prepared a very informative 45 minute video on the collapses of the buildings to specificly address some of the issues. I highly recommend that you watch it. I find it useful when twoofers ask me to back up a claim that seems to them counter-intuitive.
Is that helpful at all?
funk de fino
Dreaming of unicorns
that is a crock and lame
Dave Rogers
Bandaged ice that stampedes inexpensively through
Chris,
Maybe the opinion of a physicist might be of interest here - not a professor, but a chartered physicist with over 20 years' experience, so I'm probably as near as you'll get on the forum.
The collapses of the WTC towers involve a lot of concepts that aren't exactly everyday stuff for physicists; yield strengths of steel girders, failure modes, fire progression modelling are a few examples. In fact I get the impression that it's not even exactly mainstream stuff for structural engineers, who are generally far better placed to follow the details of the analysis than we are. In order to understand what's going on in the discussions, I've had to learn a lot, and people like Newtons Bit and Gregory Urich know all this a lot better than I do. From that alone, I suspect therefore that if you put all the papers on the WTC collapses on a physics professor's desk and asked him whether they proved that the collapses were to be expected, the most likely answer would be "Let me get back to you on that." There's still a debate here on whether Bazant's work proves the inevitability of global collapse given collapse initiation, and there are valid arguments on both sides (although, given that the model is so simplified, even this is far from casting any doubt on the likelihood of global collapse in the real world), so overall it's far from trivial or obvious.
Looking at the other side of the debate, things may get a bit simpler. There are some physicists who have written papers claiming that the towers couldn't have collapsed, and I've posted some criticisms of those papers here. In general they have some glaring errors or invalid assumptions that lie at the heart of their argument, and I'd expect a reasonably alert physics professor to pick up on those errors. However, in some cases it can be tricky to see exactly where the error lies, because of a bad habit the truth movement seems to have picked up. This is the habit of taking inadequate evidence that something has occurred and assuming it to be reliable, and in some cases assuming that it proves an even more extreme case even than the evidence suggests. For example, Kenneth Kuttler starts from an anonymous report that some rescue workers found no concrete particles larger than dust in the section of the WTC debris pile they were searching, and from this derives the assumption that (1) all the concrete in the WTC towers was pulverised into fine dust, (2) this happened to all the concrete in a given floor in the first impact of that floor on another, and (3) all this dust was immediately ejected from the tower and hence could not contribute to the collapse. This sort of nonsense can be difficult for a physicist to spot, because we tend to believe that papers like this are written with good faith and common sense. It's sometimes more an area for general skepticism and examination of claims - more in common with investigative journalism than physics.
Once we start to understand the issues and actually do some calculations, the physics-based arguments of the truth movement are like snowflakes in July, because in general they rely on stating that it is intuitively obvious that an unevaluated quantity is equal to, or unequal to, some other unevaluated quantity, and arguments like that cannot stand up when the quantities are actually evaluated and examined. However, sometimes it takes more than the experience of a physicist to know how to do the maths.
In summary, the physics of fire and damage initiated collapse is generally correct but not trivial. The physics of the truth movement is generally erroneous, and the physics of those errors is generally trivial, but the derivation often is not.
Dave
Maybe the opinion of a physicist might be of interest here - not a professor, but a chartered physicist with over 20 years' experience, so I'm probably as near as you'll get on the forum.
The collapses of the WTC towers involve a lot of concepts that aren't exactly everyday stuff for physicists; yield strengths of steel girders, failure modes, fire progression modelling are a few examples. In fact I get the impression that it's not even exactly mainstream stuff for structural engineers, who are generally far better placed to follow the details of the analysis than we are. In order to understand what's going on in the discussions, I've had to learn a lot, and people like Newtons Bit and Gregory Urich know all this a lot better than I do. From that alone, I suspect therefore that if you put all the papers on the WTC collapses on a physics professor's desk and asked him whether they proved that the collapses were to be expected, the most likely answer would be "Let me get back to you on that." There's still a debate here on whether Bazant's work proves the inevitability of global collapse given collapse initiation, and there are valid arguments on both sides (although, given that the model is so simplified, even this is far from casting any doubt on the likelihood of global collapse in the real world), so overall it's far from trivial or obvious.
Looking at the other side of the debate, things may get a bit simpler. There are some physicists who have written papers claiming that the towers couldn't have collapsed, and I've posted some criticisms of those papers here. In general they have some glaring errors or invalid assumptions that lie at the heart of their argument, and I'd expect a reasonably alert physics professor to pick up on those errors. However, in some cases it can be tricky to see exactly where the error lies, because of a bad habit the truth movement seems to have picked up. This is the habit of taking inadequate evidence that something has occurred and assuming it to be reliable, and in some cases assuming that it proves an even more extreme case even than the evidence suggests. For example, Kenneth Kuttler starts from an anonymous report that some rescue workers found no concrete particles larger than dust in the section of the WTC debris pile they were searching, and from this derives the assumption that (1) all the concrete in the WTC towers was pulverised into fine dust, (2) this happened to all the concrete in a given floor in the first impact of that floor on another, and (3) all this dust was immediately ejected from the tower and hence could not contribute to the collapse. This sort of nonsense can be difficult for a physicist to spot, because we tend to believe that papers like this are written with good faith and common sense. It's sometimes more an area for general skepticism and examination of claims - more in common with investigative journalism than physics.
Once we start to understand the issues and actually do some calculations, the physics-based arguments of the truth movement are like snowflakes in July, because in general they rely on stating that it is intuitively obvious that an unevaluated quantity is equal to, or unequal to, some other unevaluated quantity, and arguments like that cannot stand up when the quantities are actually evaluated and examined. However, sometimes it takes more than the experience of a physicist to know how to do the maths.
In summary, the physics of fire and damage initiated collapse is generally correct but not trivial. The physics of the truth movement is generally erroneous, and the physics of those errors is generally trivial, but the derivation often is not.
Dave
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Thanks. Watched the video just yesterday in fact. As always, great stuff from him. While I do appreciate your taking the time to reply, again, I'm not seriously doubting "the basic answers." Never was the intended purpose of this post. That seems to be entirely my fault for writing a poorly worded post and putting in too many trivial questions.
I fully and completely accept that 9/11 happened the way the mainstream says. Maybe the moderators might want to just delete this thread all together, as it's back-firing more than I would ever have expected.
All Engineering Journals are owned by a big bad Corporation. This corporation, like all the others control the entire world, including government. As a result, ONLY articles that are in compliance with the NWO protocols and policies are allowed to be published. The "Peer Review" is just a sham, and is always overridden by the desires of the NWO, as put forth by the "upper guys" within the Corp...so say the lord...
TAM
TAM
westprog
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It seems surprising until you think about what was happening during the collapse. As the structure failed, pieces of steel were subject to enormous forces. Steel is good at absorbing such force without shattering or bending. When enough energy is absorbed, the steel might break loose. The energy would then be released. This would be amply sufficient to hurl the steel long distances. Imagine a flexible steel rod being held vertically on a concrete floor. Keep pushing down on the rod. What's going to happen?
Once I've visualised the situation, I don't feel the need for the detailed physics.
westprog
Philosopher
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Suppose that the Western world had the situation sewn up, and had everyone blackmailed into silence. That still leaves the entire rest of the world. There are engineers in Russia, India, Japan and even Iran who could refute the consensus without consequence. They'd even get a bit of a bonus for exposing the USA. George W Bush doesn't rule the world.
Even though the Islamic world has a vast level of belief in the conspiracy theories, no reputable Muslim engineer or scientist has attempted, in a scientific journal, to show that the towers could not fall due to aircraft impact and fire.
What a great post. For me, I don't feel a need to know the collapses were "inevitable." I'm content merely to know from a physics/math perspective why they were possible, and why the times observed are possible without the aide of explosives. So am I correct in interpreting your post as saying there's no one simple equation or law or formula one can just throw at a truther and say, "there, end of discussion"?
Dave Rogers
Bandaged ice that stampedes inexpensively through
Exactly, or we would have already done it. There are just a whole raft of perfectly sensible arguments about why the collapses were energetically favourable and physically reasonable ranged against a series of logical fallacies.
Mind you, there are times when there is a simple equation, law or formula one can throw at a truther and say "there, end of discussion". The normal result is that they go away for a few days then come back saying the same thing all over again as if it never happened.
Dave
Chris lz:
One catch phrase used a lot by "truthers" is: "X defies the laws of physics". Where X is some phenomenon such as near free fall collapse.
The fact is that NOTHING defies the laws of physics (except in STAR-TREK movies!).
So next time a truther tells you that, tell him that he is simply incorrect. The laws of physics applied to the collapse of WTC 1 & 2 all the way from start to finish.
However, it is important to remember that these universal laws also apply to a CD which is mostly a gravity-driven collapse anyway! So the truthers have to have their physics straight too............
But rememeber, physics can only tell you what is possible and what is not possible.
What I found surprising once I got into my calculations was that a lot of things that look "impossible" about the collapse of WTC 1 & 2 turn out to be quite possible. That is why calculations are important. Without them you are relying on intuition and intuition is frequently wrong! For example, it is NOT intuitively obvious that objects of different mass should fall at the same rate... but experiment shows that they do!
One catch phrase used a lot by "truthers" is: "X defies the laws of physics". Where X is some phenomenon such as near free fall collapse.
The fact is that NOTHING defies the laws of physics (except in STAR-TREK movies!).
So next time a truther tells you that, tell him that he is simply incorrect. The laws of physics applied to the collapse of WTC 1 & 2 all the way from start to finish.
However, it is important to remember that these universal laws also apply to a CD which is mostly a gravity-driven collapse anyway! So the truthers have to have their physics straight too............
But rememeber, physics can only tell you what is possible and what is not possible.
What I found surprising once I got into my calculations was that a lot of things that look "impossible" about the collapse of WTC 1 & 2 turn out to be quite possible. That is why calculations are important. Without them you are relying on intuition and intuition is frequently wrong! For example, it is NOT intuitively obvious that objects of different mass should fall at the same rate... but experiment shows that they do!
rwguinn
Penultimate Amazing
Your twoofiness is showing.
You can do the calculations. I gave you the damn equation, back on page 1 of your exposure thread.
If 11s is from the top of the building, as you agree, how can 9.2s also be from the top of the building?
I saw nothing about air resistance in any answers--and the ballistic coefficient for the chunks of steel is such that in the distance they had to fall, air resistance is neglegible.
You, sir, are a liar and a fraud.
Anti-sophist
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Hey Chris. Here's my response to these issues ...
Most truthers will -claim- the building couldn't have fallen in N seconds, but they will unable to provide even the simplest explanation why.
Buildings aren't electrons. They don't follow the path of least resistance. They follow Newton's laws. The notion that there is a path of "least resistance" and that is somehow physically or scientifically relevant is fallacious.
There are several such calculations that truthers have pushed and all have been dealt with in gory detail on this forum somewhere or another.
Bazant, Greening and others have shown this is just plain false. Any truther who makes this claim simply needs to be asked to demonstrate it. If they appeal to Jones' authority, you appeal to Bazant/Greening/etc.
Most truthers will -claim- the building couldn't have fallen in N seconds, but they will unable to provide even the simplest explanation why.
The notion that objects travel the path of least resistance is an emergent property of certain physical systems based on simpler laws of physics. It's not a law of physics.
Buildings aren't electrons. They don't follow the path of least resistance. They follow Newton's laws. The notion that there is a path of "least resistance" and that is somehow physically or scientifically relevant is fallacious.
I don't see how this is inconsistent with a gravity driven collapse.
He's basically appealing to someone elses flawed calculation that the building fell too fast given the amount of energy required to create all the dust we saw. The flaw in the truther calculation is that the estimation of the quantity and finest of the dust is beyond absurd.
There are several such calculations that truthers have pushed and all have been dealt with in gory detail on this forum somewhere or another.
This is just nonsense appeal to intuition that is classic Eugene. The reality of the issue is that at impacts at 500mph and catastrophic building collapses produce physical phenomena we aren't familiar with and our inherent intuition is consequently flawed.
Affirming the consequent fallacy. It's also consistent with the smoke generated from magical pixies with laser beams shooting out of their eyes. Doesn't make it true.
Have you gotten him to show you proof of this altered data? God knows I've tried.
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I've often made the same point as what I've bolded in Apollo20's quote above. An idea, a notion, your own imagination - these things can "violate the laws of physics". Reality cannot. If something even appears to be happening outside of our understanding of the laws of physics, it is our understanding which is at fault and not the laws or the event.
But, I wanted to quote the whole post because it all bears repeating and was very well and succinctly put.
Anti-sophist
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I think this is a somewhat pedantic argument. Truthers aren't claiming that the buildings actually violated the laws of physics. They are trying to form a proof by contradiction. They are saying that if the official story of the collapse was correct, then it violated the known laws of physics, therefore the official story can't be correct.