The physics of 9/11 — including how fast and symmetrically one of the World Trade Center buildings fell — prove that official explanations of the collapses are wrong, says a Brigham Young University physics professor.

In fact, it's likely that there were "pre-positioned explosives" in all three buildings at ground zero, says Steven E. Jones.

In a paper posted online Tuesday and accepted for peer-reviewed publication next year, Jones adds his voice to those of previous skeptics, including the authors of the Web site www.wtc7.net, whose research Jones quotes. Jones' article can be found at www.physics.byu.edu/research/energy/htm7.html.

Jones, who conducts research in fusion and solar energy at BYU, is calling for an independent, international scientific investigation "guided not by politicized notions and constraints but rather by observations and calculations.

"It is quite plausible that explosives were pre-planted in all three buildings and set off after the two plane crashes — which were actually a diversion tactic," he writes. "Muslims are (probably) not to blame for bringing down the WTC buildings after all," Jones writes.

As for speculation about who might have planted the explosives, Jones said, "I don't usually go there. There's no point in doing that until we do the scientific investigation."

Previous investigations, including those of FEMA, the 9/11 Commission and NIST (the National Institutes of Standards and Technology), ignore the physics and chemistry of what happened on Sept. 11, 2001, to the Twin Towers and the 47-story building known as WTC 7, he says. The official explanation — that fires caused structural damage that caused the buildings to collapse — can't be backed up by either testing or history, he says.

Jones acknowledges that there have been "junk science" conspiracy theories about what happened on 9/11, but "the explosive demolition hypothesis better satisfies tests of repeatability and parsimony and therefore is not 'junk science.' "

In a 9,000-word article that Jones says will be published in the book "The Hidden History of 9/11," by Elsevier, Jones offers these arguments:

• The three buildings collapsed nearly symmetrically, falling down into their footprints, a phenomenon associated with "controlled demolition" — and even then it's very difficult, he says. "Why would terrorists undertake straight-down collapses of WTC-7 and the Towers when 'toppling over' falls would require much less work and would do much more damage in downtown Manhattan?" Jones asks. "And where would they obtain the necessary skills and access to the buildings for a symmetrical implosion anyway? The 'symmetry data' emphasized here, along with other data, provide strong evidence for an 'inside' job."