Before you even bother with the claim you are curious about, I suggest you substantiate this particular piece.

I'm no demolitions expert nor am I a physics major, so I can't speak as to how structures of that size behave under those conditions - though I'm sure the conspiracies have been thoroughly debunked by now. But that's the thinking.

Personally I'm more inclined to disbelieve a conspiracy theory simply because there's no way our government is competent enough to keep a secret that big for eleven years - across multiple administrations. But who knows - maybe there're better at their jobs than I'm willing to give them credit for.

Counterexamples to refute the assertion that the US government cannot keep "big" secrets:

(1) A US bomber accidentally dropped a hydrogen bomb out of an airplane into the dessert near Albuquerque, New Mexico, triggering a conventional but non-nuclear detonation. This happened in 1957 but was kept secret until 1986 -- a span of 29 years. "It was only in 1986 when an Albuquerque newspaper published an account based on military documents recovered through the Freedom of Information Act." (ref: http://www.hkhinc.com/newmexico/albuquerque/doomsday/ )

(2) The British were regularly reading encrypted German messages by around 1940. The codebreaking of the German Enigma machine was one of the greatest secrets of World War 2, and the British shared the knowledge with the Americans. This secret was revealed in 1974--after 34 years--because of two books by key intelligence figures. (ref: http://en.wikipedia.org/wiki/Ultra#Post-war_disclosures )

In both cases, at least dozens of people--but more likely hundreds of people--would have been privy to the secrets. But these two secrets did not leak for 3 decades.

Note: I am not endorsing any 911 conspiracy theories. I am simply showing that the stubborn meme that the US government cannot keep big secrets is incorrect.

a) Monica Lewinsky

b) Watergate

c) CIA Renditions

d) Waterboarding

e) More recently, intimate details of Seal Team Six & the Bin Laden raid.

f) Warrantless Wiretapping

Suffice it to say, the larger the likely public interest - is the more likely that leaks will appear.

If this was an inside job, there are not so many people (especially public people) who were behind it. They just needed to hire some Arabs (through several proxies) and train them to intercept the airplanes. And I'm sure those Arabs didn't know who was really behind it (they were sure it was Osama who could be an agent or a legend). Then make sure the secret services somehow fail to do their job at time X. Then eliminate/threat/silence those people at lower levels who couldn't understand some actions/lack of actions and were suspicious about that.

It isn't so hard for people with sufficient power and money, don't you think?

It's not that I doubt that people would want to (and perhaps have motive) to pull off a stunt like this.

It is the subsequent burying of the evidence and keeping it a secret for so long - something that has attracted more scrutiny than any other terrorist attack in recent history.

Either the gov't is far more sophisticated than we imagine, which I doubt - or the theories are just that. Theories.

I am more inclined to believe the latter.

As I said, I haven't bought into this theory yet. Just want to get other opinions on whether or not it makes sense in this particular case.

In short, the reason that the towers' collapses looked like controlled demolitions is because controlled demolitions don't rely on the explosives to destroy the building, they rely on destabilising it enough that it falls in on itself. The "controlled" part is just making sure it collapses inwards.

Each story had about 480MJ worth of energy. That's equivalent to about 1/10 of a ton of TNT. That's each story falling just one floor mind you. http://www.wolframalpha.com/input/?i=%281500000+tons+%2F+110...

For the North tower that's 120 floor equivalents as the 15 floors fell, about 12 tons of TNT.

For the entire tower that's 700 tons of TNT (assuming the mass of the tower is distributed evenly, which it isn't, but it's still a huge amount of energy).

What is that in relation to the speed of free fall of that floor? Is that roughly half? - i.e. in total free fall, you would expect that the floor would fall at 9.8 * 10^8 kgm^2/s^2?

Thanks!

Gravity is 9.8 m/s^2. Not 9.8 * 10^8!!! And the result is kg m^2/s^2 not m/s^2.

The result assumes a free fall at 1 g. I multiply it by g in order to accomplish that. (It's on earth, it can't really fall slower. If you want it to fall slower, the only thing it can do is fall, hit something and stop, then fall again - but that has 0 impact on the energy released! The energy released does not care if the building hit something and stopped momentarily in the processes.)

I know the result looks superficially like the units for gravitational acceleration but it's not, it's also multiplied by kg * m. i.e. I multiply gravity by mass and by how far it fell. The end result is the units for energy.

If you look up Joule http://en.wikipedia.org/wiki/Joule you'll see that it is defined that way.

There is a reason they push so hard to make sure you do the units correctly in Physics - you can gain a lot of insight into what you are calculating if you manipulate them properly.

So, in concluding...what would you say - based on your analysis here - about the assertion that this may have been caused by a 'controlled demolition'.

If you can just summarize your findings here, into a succinct statement that would be greatly appreciated :)

E.g. "The theories don't make sense, because as we saw here....X, Y & Z." or "The theories DO make sense, because Z, Y & X".

Where did you get the 15000000 tons figure from.

Also..what relation does 480MJ of energy have on the rate at which the building would have collapsed?

Are you debunking the theory that it was explosives, or supporting it?

I'm saying that there is more energy in simply the tower falling than there would be in any explosive. So it would not fall any faster with an explosive - there already is much more energy there than needed.

How are you sure that they wouldn't be able to use "more than enough" explosives though? 1/10 of a ton of TNT on each floor, sounds like a lot...but doesn't sound like an enormous amount.

Can you put that in terms that a layman may understand?

Thanks.

P.S. I would love more details, so that I can properly refute these claims based on physics and facts - than just based on philosophy and intuition.

1/10 of a ton (200 pounds) of explosives is a staggering amount in comparison. The energy involved in the building falling down swamps the explosives by such a large degree that you couldn't even tell the difference.

Remember that the fire did the same thing that a controlled explosion would do: Weaken the central support. The fire by softening the metal, an explosion by cutting it.

A controlled demolition does not actually explode the building, all it does is weaken the support, and gravity does the rest.

Just think, wouldn't those who run the world spend just several hundred lives and two buildings to gain a so profitable war on terror, the Patriot Act, and a new permanent enemy (the terrorists!) to keep the people in terror and pull more and more of their rights to "protect them".

Hypothetically, if this was a conspiracy, then Bush's involvement would have been at the very most listening to options and then selecting one. For the same reason I can, in the same sentence, say that America invaded Iraq and that Bush isn't a trained soldier.

(For the record I don't believe 9/11 was a conspiracy.)

Quote from 911sharethetruth.com:

"""Initially, most of us fell for their version of the events. But then came the slip-ups. The leaseholder of the World Trade Center admitted on PBS in 'Rebuilding America' that WTC-7 was 'pulled' on 9/11 (See video here in Windows Media Format - http://www.911sharethetruth.com/extras/SilversteinBdg7.wmv), which is the standard slang for controlled demolition.

Look at the tapes from that day when TV anchors, Aaron Brown and Dan Rather first said the very same words about the collapses. Firefighters and rescue workers talked about explosives and bombs going off, all over in the buildings. Recall the horrific images of the over 100-story towers coming down at free-fall speed, defying the laws of physics. Recall the engineers who first stated that the planes and fires alone could not have caused the deadly collapse. Now the evidence is gone, witnesses silenced, and an independent, real investigation never happened. Sure, it is hard to accept that we have all been fooled so long, but only discovering and facing the truth will set the U.S. free.""" - 9-11 Truth Activist of Northern California

As for the politics, whatever. Bush/Cheney allowed 9/11 to happen. And then they capitalized on the aftermath. So what? There's no evidence that is actionable. You're outraged? Big deal. While you're refighting past battles, the bad guys are gleefully stealing your future.

Having said that, the 9/11 Truther groups are basically cults. No different than the La Rouchians, Scientologists, climate change deniers, Clinton Killed Vince Foster, etc. People addicted to anger busy disempowering themselves.

Behind every fad or movement, there's someone making a back.