Aidan wrote:


That looks very much like a controlled explosive demolition.

If the collapse had been due to structural damage to one side and
internal fires, then I'd have expected a corner or the side of the
building to collapse.

Anyone know the story behind this? Has someone been tampering with the
video? Could concrete spalling explain the 'detonations' or could they
have deliberately demolished it, after the initial damage, to prevent
it collapsing over the surrounding area?

Sorry to wander off topic; I'd like to know & you're a knowledgeable
lot. The rest of the conspiracy theory is bolleaux; the Pentagon was
hit by a commercial airliner & a plane diving into the ground under
power really could bury itself in a 30' hole.

The best non-mathematical explanation for this problem is in the PBS
Nova program, "Why the Towers Fell," originally broadcast on Tuesday,
April 30, 2002. This program goes into some depth on the technical
issues involved in the catastrophe, and why the method of construction,
combined with the method of insulating the internal supports, ensured
the quick collapse of the twin towers (as well as why they fell
straight down, which seems counterintuitive). Public television at its
finest, and something you'd never see from a commercial network. It
just takes too much time and costs too much to do something like this
well. The companion web site for that program has all of the details
(including some things not covered in the program), and is extremely
well-done, too:

http://www.pbs.org/wgbh/nova/wtc/

Look particularly at the section: "The Collapse: An Engineer's
Perspective".

Anyone who didn't see the program might be able to get it from a local
library. I believe you can also purchase a DVD of the program from
WGBH. Anyone who did see the program but missed checking the website
missed quite a bit, too.

WTC7 had emergency generators and the fuel for those generators caught
fire, also ensuring its eventual collapse later from essentially the
same cause. As it had been evacuated, the NYFD didn't concentrate any
rescue efforts there.

The OP's conclusions about the collapse of the towers are all
incorrect.

Cheers
Chris

Chris wrote:

lot. The rest of the conspiracy theory is bolleaux; the Pentagon was

The best non-mathematical explanation for this problem is in the PBS
Nova program, "Why the Towers Fell," originally broadcast on Tuesday,
April 30, 2002.

Yes, I might have seen that, or was it a Horizon programme?

The cause of the collapse of the twin towers was wholly plausible and
consistent with the events.

The collapse of WTC7 seems odd. I'm looking for a similarly plausibe
explanation.
It's a real question to which I don't know the answer. I do not
believe there was any conspiracy or prior knowledge amongst the US
security agencies.

http://www.pbs.org/wgbh/nova/wtc/

Look particularly at the section: "The Collapse: An Engineer's
Perspective".

Thanks for that, I'll look into it.

Anyone who didn't see the program might be able to get it from a local
library. I believe you can also purchase a DVD of the program from
WGBH. Anyone who did see the program but missed checking the website
missed quite a bit, too.

WTC7 had emergency generators and the fuel for those generators caught
fire, also ensuring its eventual collapse later from essentially the
same cause. As it had been evacuated, the NYFD didn't concentrate any
rescue efforts there.

Allowing the building to burn out seems to have been the only sensible
course of action.
I'm not convinced that the generators' fuel (diesel?) could have
fuelled the fire, but am open to persuasion. I'd have expected it to
partially collapse or twist in falling.

The OP's conclusions about the collapse of the towers are all
incorrect.

Yes.

The puffs of black smoke do look like explosions. I think you'd get
that with some forms of HE (TNT?) but not with more modern HE,
(Amatol?). If the demolition was preplanned, I'd have though the MIB
would have arranged some less conspicuous & smokeless means of bringing
it down. If it wasn't HE, then what would have caused it?

"Aidan" wrote in message
oups.com...
Chris wrote:

lot. The rest of the conspiracy theory is bolleaux; the Pentagon was

The best non-mathematical explanation for this problem is in the PBS
Nova program, "Why the Towers Fell," originally broadcast on Tuesday,
April 30, 2002.

Yes, I might have seen that, or was it a Horizon programme?

The cause of the collapse of the twin towers was wholly plausible and
consistent with the events.

The collapse of WTC7 seems odd. I'm looking for a similarly plausibe
explanation.
It's a real question to which I don't know the answer. I do not
believe there was any conspiracy or prior knowledge amongst the US
security agencies.

http://www.pbs.org/wgbh/nova/wtc/

Look particularly at the section: "The Collapse: An Engineer's
Perspective".

Thanks for that, I'll look into it.

Anyone who didn't see the program might be able to get it from a local
library. I believe you can also purchase a DVD of the program from
WGBH. Anyone who did see the program but missed checking the website
missed quite a bit, too.

WTC7 had emergency generators and the fuel for those generators caught
fire, also ensuring its eventual collapse later from essentially the
same cause. As it had been evacuated, the NYFD didn't concentrate any
rescue efforts there.

Allowing the building to burn out seems to have been the only sensible
course of action.
I'm not convinced that the generators' fuel (diesel?) could have
fuelled the fire, but am open to persuasion. I'd have expected it to
partially collapse or twist in falling.

The OP's conclusions about the collapse of the towers are all
incorrect.

Yes.

The puffs of black smoke do look like explosions. I think you'd get
that with some forms of HE (TNT?) but not with more modern HE,
(Amatol?). If the demolition was preplanned, I'd have though the MIB
would have arranged some less conspicuous & smokeless means of bringing
it down. If it wasn't HE, then what would have caused it?


You're more likely to get a good answer to that question by asking real
engineers than posting to newsgroups like rec.arts.tv or
alt.politics.democrats.d where conspiracy theories are rampant :-)

I'm not sure if the fall of WTC7 has been explored in any documentaries yet.
Maybe on Discovery or The Learning Channel?


--
Rhino

Rhino wrote:

You're more likely to get a good answer to that question by asking real
engineers than posting to newsgroups like rec.arts.tv or
alt.politics.democrats.d where conspiracy theories are rampant :-)

I posted to Uk-DIY & hadn't noticed the post & reply was cross-posted
to fruit & nut HQ. I don't subscribe to the conspiracy theory, I'd just
like to know what's going on. A modified video seems most likely, at
present. I'm an engineer.

So, you don't know either?

Aidan wrote:

I posted to Uk-DIY & hadn't noticed the post & reply was cross-posted
to fruit & nut HQ. I don't subscribe to the conspiracy theory, I'd just
like to know what's going on. A modified video seems most likely, at
present. I'm an engineer.

So, you don't know either?

Hi, Aidan. If you want an engineering answer to your questions, you
might want to look at the NIST (United States National Institute of
Standards and Technology) "Final Report of the National Construction
Safety Team on the Collapses of the World Trade Center Tower ".

http://wtc.nist.gov/reports_october05.htm

The links on this page are to enormous .pdf files. Don't do this with
a phone modem!

In fact, the major cause of the collapse of the twin towers, and the
sole cause of the collapse of WTC7, was the fuel-fed fire. And the
collapse of WTC7 was of particular interest because it was the first
skyscraper to collapse because of fire alone.

Among other sources of evidence, NIST engineers went through all kinds
of video frame-by-frame. Any legitimate visual recorded evidence was
taken into account.

Of course, an engineering answer wouldn't satisfy the conspiracy
theorists. But the facts and the engineering conclusions are there for
anyone who has the training and the patience to go through them.

No need to demand a major investigation -- it's already been done, and
done comprehensively and exhaustively.

Cheers
Chris

Chris wrote:

So, you don't know either?

Hi, Aidan. If you want an engineering answer to your questions, you
might want to look at the NIST (United States National Institute of
Standards and Technology) "Final Report of the National Construction
Safety Team on the Collapses of the World Trade Center Tower ".

http://wtc.nist.gov/reports_october05.htm

That looks like what I wanted.
Thanks very much!