[alancalverd]

I think NIST can analyse a video reasonably well.

[Aemilius (OP)]

I'll take that as a "Yes".

[Aemilius (OP)]

I think I'll skip any further discussion of this, it's actually starting to give me the creeps....

I have Dr. Alan Calverd Ph.D. (a well seasoned career research physicist) arguing that not only is it possible but probable that the lower part of the building progressively/naturally collapsed in a way that resulted in the upper part of the building actually accelerating as it descended symmetrically straight down through itself, through the path of greatest resistance (below left), and also, incredibly, that driven on solely by gravity it quite naturally continued to accelerate so nearly to gravitational acceleration (below right) as to require very careful calculation for any difference between the two fall times to be detected.... preposterous!

There appears to be a considerable number of views of the thread but, eerily, not one member is commenting on the veracity of what I've had to say, and neither is anyone commenting on the veracity of what Dr. Calverd has had to say either.... very strange indeed!
 
A clearly irrational and insulting post made by Bored chemist slips past the moderators, but I am openly admonished for not "keeping it friendly" when I bluntly challenge/recognize his absurd baseless assertion for what it is.... a now confirmed load of rubbish!

Finally, CliffordK has explained to me (privately) that he and the other moderators decided that arguments about whether or not two jet airplanes caused the building to collapse seemed best suited to the "That CAN'T be true" subforum, though no airplane struck the building (even the NIST says airplanes had nothing to do with it) and airplanes are mentioned nowhere in the thread as having had anything to do with it either.... extremely curious!

To top it all off, compared to the meticulously factual and clearly defined hard science question I posed concerning the obvious impossibility of even near free fall occurring during any natural progressive structural failure, there seems to be no problem with topics like how much to tax the price of a drink or baggy shirts causing some guy to sweat being considered as "General Science"..... incredible!

Not meant to offend, I just don't get any of that. Thread abandoned (for now).... Lock it, leave it, do as you wish.

[Aemilius (OP)]

Let's have an explosion.

Right Dr. Calverd, we might as well, since, as we've both really
known all along, it's the only logical way to explain observations.

WTC7 - ANALYSIS AND CONCLUSION

A complete Prima Facie Empirically Verifiable Scientific
Method Driven Graphical Target System Analysis and
Conclusion arrived at by Process of Elimination



"Analogical models are a method of representing
a phenomenon of the world, often called the 'target system',
by another, more understandable or analysable system. They
are also called dynamical analogies." - Wikipedia

The exceptionless condition required for gravitational acceleration
to occur has been known for centuries....



....and is, as you pointed out initially "The condition under which
a body is, literally, free to fall under the influence of the local
gravitational field with no resistance to its acceleration."....



The Control, or source system, that appears to the right of the
Scenario, or target system, in many of the animations is
intended as a reminder of that, and also signals the
beginning of a comparison....



We can still know with certainty what condition exists beneath
an object as it falls....



....even though we may not be able to see into the space
beneath it as it does....



Buckled columns, whether one or a hundred, whether one at a
time or all at once (or any combination thereof) won't just go
from 100% to 0% when they buckle, they'll gradually
decrease in strength while they buckle
and that takes time....



The mechanism of buckling (a mode of natural progressive
structural failure), whether caused by heat....



....or by overloading....



....or by other modes of natural progressive structural failure
such as impact induced fracturing....



....or fracturing caused by overloading....



....or any other mode or combination of modes of natural
progressive structural failure absolutely cannot match or
create the exceptionless condition required for gravitational
acceleration to occur, it's literally impossible (naturally excluding
the consideration of bridges and other structures that pass through
air wherein the condition required for gravitational acceleration to
occur exists inherently as a structural feature). There is no such
thing as structural gravitational acceleration....



The progressive collapse of the building (NIST probable
collapse sequence starting with column 79 on the left)....



....that essentially happens all at once....



....is clearly physically inconsistent with what we
empirically know of natural progressive structural failure
(defined as a time consuming process of individual, sequential
or simultaneous failure involving one or a number of related
structural components). It's a physical impossibility for the
lower part of the asymmetrically damaged building
(reportedly three core columns and nine perimeter
columns) to have naturally progressively collapsed
in any way that could result in the upper part of
the building symmetrically descending as a single
unit straight down through itself.... 



....at anything near gravitational acceleration (NIST
probable collapse sequence starting with column 79 circled
below) for any period of time....



A building collapse like that seen below resulting from any
natural progressive structural failure of a steel frame building
including a 105 foot 2.25 second period of gravitational
acceleration of the upper part of the building as a single
unit is an absolute physical impossibility....



....as nowhere in the course of any such collapse or
structural failure is the exceptionless condition required
for gravitational acceleration to occur seen to arise beneath
the upper part of the building as the scenario
plays out to completion....



There is absolutely no mode or combination of modes
of natural progressive structural failure driven solely
by gravity that can ever match or give rise to the
exceptionless condition required for free fall to have
occurred at any point during it's descent....



The scenario playing out below is an absolute physical
impossibility. Just as there is no such thing as structural
gravitational acceleration, nor is there any structural failure
mode known as natural progressive structural
gravitational acceleration....



There is simply no point during a natural progressive gravity
driven collapse of any modern steel frame skyscraper
where one could realistically say....

"Hold it.... right there! That's the point past which all
the welded and bolted together steel columns and
structural components that were supporting the building
just a moment ago (with an area greater than that of
a football field) will undoubtedly be observed beginning
and then continuing to behave in a manner indistinguishable
from  air (below left) for at least the next eight stories,
or 105 feet of its descent (below right). It would take very
careful calculation to tell apart the fall times shown below
during this free fall period of the ongoing natural
progressive structural failure"....



For the 105 foot 2.25 second period of time that we know
the upper part of the building literally fell as a single unit at
gravitational acceleration we know it can not have been
using any of it's potential energy to crush the building
contents, columns and other structural components
beneath it and undergo gravitational acceleration
at the same time (as illustrated by this
frangible impedance scenario)....



It's physically impossible for the lower asymmetrically
damaged part of the building to have naturally progressively
collapsed in any way that could result in the upper part of
the building actually accelerating as it descended symmetrically straight
down through itself as a single unit through the path of maximum
resistance (below right), and then, driven on solely
by gravity, actually continue to accelerate so nearly to
gravitational acceleration (below left) as to require very
careful calculation for any difference between
the two to be detected....



Some other force powerful enough to quickly remove all
support from beneath the upper part of the building as it
descended must be introduced to explain the observed
rate of descent during the 2.25 second period of gravitational
acceleration. For the 2.25 seconds that the building literally fell
at gravitational acceleration, no other force powerful enough to
quickly remove all support from beneath the upper part of the
building was seen to be introduced from outside the building,
and no other force powerful enough to quickly remove all
support from beneath the upper part of the building is known
to have existed inside the building as an element or normal
function of it's infrastructure. For a load supported by a column
to descend at gravitational acceleration, all support must be
quickly removed, there's absolutely no other way. It must be
knocked out, pulled out, blown out, vaporized etc.
Since no eight story tall boulders were seen rumbling
through Manhatten that day that could have
quickly knocked out all support....



....and no suspicious looking Frenchmen were spotted rigging
for verinage (another form of controlled demolition) the night
before that could have quickly pulled out all support....



....and no bombs or rockets were seen to be dropped on/fired
at it that could have quickly blown out all support....



....and no giant laser beams or other secret weapons were
being tested in the area that could have quickly
vaporized all support....



....and no other force capable of quickly removing all
support from beneath the upper part of the building existed
in the building as a normal function of it's infrastructure (blue)....



....it naturally follows that whatever the other force was
that must be introduced to explain the observed 105 foot 2.25
second period of gravitional acceleration of the upper part of the
building as a single unit, it must have been introduced some time
before the event, and unless it can be shown how the other
force that must be introduced either during or just before
the collapse of the building was introduced from outside
the building, or that it was already existing inside the
building as a normal function of it's infrastructure, the
process of elimination really leaves only one possible
explanation for the building's behaviour. Some energetic
material powerful enough to quickly remove all support
from beneath the upper part of the building during the 105
foot 2.25 second period of gravitational acceleration must
have been physically transported inside the building some
time before the event, it had to be brought in. The
explosion model is the only one....



....that can realistically match and empirically be
expected to create the exceptionless condition that
we know must have existed....



....beneath the literally falling visible upper part of
the building as a single unit during its observed largely
symmetrical descent at gravitational acceleration for
approximately 105 feet in 2.25 seconds....



The undisputed (both the NIST and independent researchers
alike agree) observation of a significant well defined period of
gravitational acceleration of the upper part of the
building as a single unit....



Stage 1 (0 to 1.75 seconds): acceleration less than
that of gravity (i.e., slower than free fall).

Stage 2 (1.75 to 4.0 seconds): gravitational
acceleration (free fall).
During Stage 2, the north face descended essentially
(displaying all the absolutely necessary, extremely important
features) in free fall (any motion of a body where gravity
is the only force acting upon it), indicating negligible (so
small or unimportant as to be not worth considering) support
from the structure (approximately 40,000 tons of
structural steel) below.
 
Stage 3 (4.0 to 5.4 seconds): decreased acceleration, again
less than that of gravity.



....means that an explosion, or a number of explosions, must
have occurred that was powerful enough to quickly remove all
support from beneath the upper part of the building (below right),
either all at once or incrementally in advance of its descent,
permitting it to descend at gravitational acceleration as a
single unit for the observed period and under the
exceptionless condition required (below left) for
gravitational acceleration to occur....



The building was brought down by explosives.

[PmbPhy]

Well Bored chemist, your last post makes just as much sense as your first.... none. At least you're consistent!

A very accurate observation.

[jccc]

free fall is rolling with the punches instantaneously

[Aemilius (OP)]

Chris tells me (privately) that I've had several complaints now so genuine apologies to all for ruffling any feathers (including yours Chris), that was never my intention. From the start all I've really been interested in, all I've really been trying to do, is get to the bottom of it.... and I have now.

Thanks again for engaging me and for helping me sort it out Dr. Calverd, it was a real marathon, and I had fun making the animations too, wouldn't have come up with them otherwise.

I must say though (inhaling deeply) that in view of the overwhelming simplicity of the governing physical principle here involving the Law of Conservation of Energy as applied to a falling body I remain completely baffled as to why there was never any other input by any of the other people here apparently so well qualified to judge the analysis that really should have quickly and naturally led to a simple confirmation or denial by consensus of the veracity of the information conveyed by it as one would normally expect in response to such a fundamentally structured high school level empirically verifiable analysis like this (Reply 143) from such a venerable academic institution as University of Cambridge.... where Isaac Newton himself once held the vaunted Lucasian Chair.

Emile Cole