The collapse of New York's World Trade Centre on September 11, 2001 is arguably one of the most well documented events in human history. Less well documented is the controversy over why the buildings fell as they did.

At the time of writing, 357 architectural and engineering professionals have signed a petition which directly challenges the National Institute of Standards & Training's official finding that the destruction of these massive buildings was caused solely by structural damage from the impact of jet airliners and the resulting fires.

The petition, demanding of Congress a truly independent investigation, states, in part:

"...the 9/11 investigation must include a full inquiry into the possible use of explosives that may have been the actual cause behind the destruction of the World Trade Center Towers and WTC Building 7."

This alarming statement is based on evidence from many sources, including observations of the structural behaviour of the towers as they collapsed, the known characteristics of steel framed buildings, eyewitness testimony of explosions, and research into the chemical composition of dust recovered from the collapse zone.

Current research indicates that an incendiary (thermite) may have been used to sever the massive box columns of the towers, causing the buildings to plummet to the ground at close to free-fall speed.

Chemical analysis has been conducted by a multi-disciplinary team led by

Professor Steven E. Jones and the results published in the Journal of 9/11 Studies.

The membership of Architects and Engineers For 9/11 Truth is worldwide, and qualified Australians have made contributions. Dr. Frank Legge, a chemist, has co-authored a peer reviewed paper, and Dr. David Leifer of the Faculty of Architecture at the University of Sydney is a registered member of the group.

A major focus of research is the mysterious collapse of the

47 storey WTC 7 (Salomon Brothers) Building, which was not hit by any plane, yet suddenly collapsed into its own footprint late in the afternoon of September 11, 2001.

Building 7 came down in six and a half seconds, generating a massive dust-cloud similar to the one that had enveloped Manhattan when the Twin Towers collapsed earlier the same day.

Researchers contend that only explosives could have provided enough energy to cause the pulverisation of thousands of tons of concrete into dust, and they highlight the symmetrical, free-fall collapse of the building through the path of greatest resistance, indicating that the supporting columns offered no resistance to the falling mass above.

Historically, the only way a modern office building has ever been made to collapse vertically in free-fall, as observed in WTC Building 7, is through the use of shaped cutter charges detonated in a timed sequence.

This procedure is known as controlled demolition, and requires a precise placement of explosives which are designed to cut through supports successively, usually from the bottom up, pulling buildings down under their own weight.

The collapse of Building 7 is visually identical to a controlled demolition, as illustrated in a side by side comparison on Youtube. Demolition expert Danny Jowenko has gone on record confirming this observation.

"A team of experts did this", he said.

The essence of why we need a new investigation into the World Trade Center collapses is summed up in a recent paper by Dr. Frank Legge:

"As no reports have come to light of any steel framed buildings collapsing due to fire, and as all steel framed buildings which had collapsed had done so due to explosive demolition, the logical way to have started the investigation of this surprising event would have been to question whether explosives had been used. This apparently did not occur.

The organisations carrying out the investigations clearly selectively collected data and contrived arguments to support the fire theory and ignored contradictory evidence. This is in defiance of the scientific method and flouts the ethical standard of behaviour which the public is entitled to receive from their paid servants."

The hypothesis of controlled demolition finds further support in many eyewitness accounts, including live TV coverage, which described massive explosions in the lower levels of the World Trade Center prior to the collapse.

William Rodriguez, an acknowledged hero of 9/11 who single-handedly rescued fifteen people from the North Tower, described a massive explosion in the basement which occurred before the first plane struck, pushing him upwards out of the seat of his chair.

The New York Fire Department's oral histories project contains 118 witness statements which are strongly consistent with explosive demolition. Incredibly, none of this shocking testimony was included or acknowledged in any official investigation, including the 9/11 Commission.

There is a groundswell of public pressure from family members of victims and ordinary people the world over, to re-open the investigation of 9/11. As seen in the groundbreaking film 9/11: Press For Truth, it was due to the pressure of a group of victim family members, known as the Jersey Girls, that the 9/11 Commission was created, and yet that same commission failed to answer the majority of questions raised by these courageous women.

Films such as Loose Change and 9/11 Mysteries have been viewed by millions on the internet, and opinion polls have consistently shown that a large proportion of the public does not accept the official narrative of 9/11. Many believe there has been a major cover-up, while others believe that September 11 was an "inside job".

As an Australian, I believe there is an urgent need for a new investigation for several reasons.

First, there is the war in Afghanistan, which has already claimed thousands of lives, and appears to have no end in sight. If the 9/11 official narrative proves to be false, then the attack on Afghanistan may be a war crime.

Second, there is the continued erosion of civil liberties in the form of anti-terror legislation, and increases in police powers of surveillance and detention, which relies largely on 9/11 as the primary justification.

Finally, there are core values of truth, decency and justice at stake, which I wish to uphold and which I ask all Australians to join me in upholding as I say to our elected leaders, with all due respect, we need a new investigation.