Since my name was invoked by the OP,
I thought I'd lend my perspective, albeit perhaps too late. I hope the contentious nature of this thread hasn't totally scared away
chris lz already. The questions aren't new, but they're asked in good faith, so why not give reasonable answers?
So I'm curious, to what extent would the most basic physics claims supporting a “natural collapse” be accepted by all (or almost all) physicists? I'm confining myself to the twin towers for now. For instance, what formulas/calculations, etc., if shown to the average college level physics professor, would unhesitatingly be endorsed; and which ones (given by truthers) would be firmly rejected? Would they automatically reject Ross and Kuttler, in favor of Greening and Mackey, for example? Or might they be divided?
It's hard to say what
all physics professors would say, but in general, I'm comfortable that the Truth Movement claims would be rejected out of hand. You are welcome to test this yourself with your local college. It's entirely possible you will find an oddball prof here or there who buys into it (the Truth Movement has found a handful, and throw their names around as though they were worth a million Ameros each), but I would be stunned indeed if an entire
department agreed, anywhere in the world.
I say this for several reasons:
- The structural engineering faculty at BYU, former home of Steven Jones, completely disagreed with his conclusions, while pointedly making no move to censor him
- Several university efforts have looked into Sept. 11th, including top-of-the-line schools MIT and Purdue, and agree with no conspiracy theories
- As you've already seen, there is a multitude of published work from legitimate sciences about the physics of Sept. 11th, and while not all of it agrees with NIST, none of it agrees with the conspiracists
So that's my evidence. Again, it's an experiment you can test for yourself, and you should if you have such serious doubts.
1 As Prof. Jones likes to say, explosives were needed to “eliminate” or remove the mass to account for free fall/ almost free fall, every x floors.
Dr. Jones must be very careful about what "almost free-fall" means. As I've explained before, collapses are rapid. Only a second or two of resistance translates into an enormous amount of energy expended on the structure, much more than any feasible explosives situation could provide. See post
here or Appendix A of my whitepaper.
2 -The twin towers fell into their own footprints (approximately, at least). And the related claim it took the path of “most resistance.” (comment: what would the path of most resistance actually be?)
Falling vertically actually
is the path of least resistance. Getting the structures to topple, or shedding mass over the sides such that collapse was arrested, requires energy to move all that mass sideways. Where could it have come from?
The Towers were so enormous -- both in mass, and in
width, that there's just no way. Even if you imagine the upper block rotating as it falls, it still has to crush tens of floors on one side just to rotate, say, 45 degrees. You cannot have tipping without crushing. Crushing without (much) tipping requires
less energy than crushing
and tipping.
The above quote is from EugeneAxeman, one of the more sophisticated 911 skeptic posters I’ve read on the internet. Here are a few more of his specific claims:
burning steel pieces (weighing thousands of pounds) of the towers were hurled outward for hundreds of feet at speeds of about one hundred feet per second. . . . . The other reason for ignoring the details of the collapses was that certain troubling aspects, [i.e. like the above observation], would not need to be analyzed.
We've seen Mr. Axeman here, too. He did not strike me as particularly well educated in matters of science.
His observation is actually evidence
against explosives. As he notes, the pieces seen to have flown the furthest were very large. (I dispute his estimate of "hundreds of feet per second;" the fastest velocity supported by evidence is on the order of 50 feet per second.) This makes sense, because larger pieces are less affected by wind resistance, right?
Well, the problem is that pieces being accelerated by blast is
also much like "wind resistance." The bigger pieces aren't accelerated as much as smaller pieces. Had explosives been to blame, we would see smaller pieces fly farther than the bigger pieces. Unless you expect me to believe that a blast big enough to toss those girders couldn't have broken off anything else. Such a surgical yet huge explosive is simply not possible.
In
this post (and in my whitepaper) I explained this, and later on in that thread I work out the amount of explosives needed to throw large chunks of steel. The amount works out to be a minimum of perhaps 500 kg of TNT, just to throw a modest steel column segment 600 kg in mass the distance claimed, under optimistic assumptions. Such as, that doesn't include the energy to break it loose in the first place -- just to throw it.
Unless you can believe there were half-ton charges of demo going off without being heard or seen by anyone, there's no way you can accept this as evidence of explosives.
Calculations which took into account the energy consumption required to pulverize the buildings as observed show that the collapses took place at a rate over three times that which was possible by gravity alone.
(Where is he getting “over three times” from?)
I have no idea. Like explained above, the collapse time is totally believable, even if you can't hack through the BLBG paper. Even a high-school level argument explains why the ~ 15 second collapse times are reasonable.
In reality, steel bends, and over 200 supporting columns, along with their cross-bracing would need to get out of the way at once to allow the upper section to fall.
The "at once" argument is laughable on its face. Did the columns "all fail at once" when the aircraft hit? Nope. Some did, most didn't. Did the columns "all fail at once" when the top of the building began leaning? Nope.
At the critical moment of loss of stability, however, many columns can fail in a fraction of a second. Think of it this way: Suppose you have a sturdy table with eight legs, and you put an enormous amount of weight on it, enough that it starts to creak and sag. Then kick out one of the legs. The table will probably stay standing, but it will complain. Kick out another leg. Eventually, when you kick out a leg, the rest will all collapse, and it will happen faster than you can see. But that doesn't mean they all failed
at once. It's just what happens when there's no more reserve capacity in a highly energetic system.
The physics I know tells me that when a building collapses, the energy is distributed across the surface area and the total mass of the falling section cannot be assumed to be focussed in a single point.
In fact, due to the inevitable fracturing and fragmenting suffered by the falling section, the collapse is better modelled as a series of interdependent impacts.
Kuttler simplified the model, but in the direction which would aid the gravity-driven presumption. Instead, it validated that the fall times were too fast, given the amount of material being destroyed by the collpase.
Poster
Dave Rogers has already
adequately addressed the Kuttler paper. There are numerous totally bizarre assumptions, none of them backed by observation or physics, that leads to his incorrect answer, such as the claim that 100% of the concrete was pulverized
at altitude rather than later -- even Steven Jones points out that much concrete survived, as a way to shut up the Beam Weapon loonies. He also arbitrarily assumes the structure should continually and gradually resist the collapse, much like a giant sponge, rather than fail floor-by-floor in sharp and discrete impact events. All in all, a rather stupid paper.
I have access to several videos of the tower collapses, and they all show a characteristically high volumes of smoke being expelled from the buildings just prior to their vertical movement. The smoke is consistent with the color of aluminum oxide generated from thermite reactions
The Towers were full of smoke, and at the moment of collapse initiation, the NIST theory predicts several floor systems giving way. It's no surprise at all that "high volumes of smoke" would be expelled. The smoke is the color of the smoke. Aluminum oxide powder is roughly the same color as wallboard, so this is hardly a compelling argument.
The fires were not hot enough to weaken the steel to the point of failure, although efforts have been made to alter data and reality in order to meet that criteria
This comment is nonsensical. The "point of failure" depends on the load. Steel can fail at room temperature, if you load it enough. NIST explains in gruesome detail the temperatures and the loads it predicts, as a function of time, and these do indeed lead to failure.
Even the NIST investigators had to distort the data to create their model where collapse inititiation would occur. Their own lab tests failed to duplicate the condition where the steel would sag to the degree to which they claim took place
This is simply wrong. Mr. Axeman, like so many of his fellows in the Truth Movement, has misunderstood the point of the ASTM E119 tests in NCSTAR1-6B. They were designed to see if the
intact floor trusses would pass their fire certification. They bear no direct relationship to trusses with damaged fireproofing or structural damage from impact, and the test results are not comparable. You may as well argue that your car can go 140 MPH, because that's what
Road & Track said, even though your car has a flat tire.
So, for 1-6 at least, are we dealing primarily with questions of elementary physics? Or does one really need to go more in depth? What would be your one favorite formula/calculation/etc (if any) to quote when replying to any of these truther claims? (And, for any skeptics, what would be your favorite one that you think would refute the "natural collapse" physics?)
For questions 1-5, it only takes a modicum of physics understanding. Any competent Physics major should be able to find the errors and explain them at a coarse level. Question 6 is trickier simply because of the deliberately confusing nature of Kuttler's paper.
Reports like the NIST Report can be read and understood with, say, an undergraduate level of physics or engineering -- although it is rather dense and detailed. Actually disputing it would be difficult without post-graduate training, but there are researchers (real ones) who do exactly that, e.g. Dr. Usmani at U of Edinburgh or Dr. Quintiere at U Maryland. But all of these folks strongly disagree with any conspiracy angle. They're merely looking at issues of precision, special vulnerabilities of the structural design, etc. Not postulating explosives.
As is common for the Truth Movement, few of the questions above are well-posed, and several depend on Truth Movement lore that will throw an unprepared reader for a loop, without prior exposure to their ideas. This is all typical behavior for pseudoscientific groups, who are extremely fond of inventing terms and fixating on details that most people may have never heard of. It lends them an undeserved air of thoroughness and legitimacy, and makes it harder for people to challenge them. But if one takes the time to look closely, they're still wrong.
Hope that helps.
