Federal report responds to Internet's 9/11 theories

As the fifth anniversary of the Sept. 11, 2001, terrorist attacks approaches, the federal government has issued a response to scientists and others who still doubt the government's explanation of how the World Trade Center towers in New York collapsed.

Questions over whether the towers collapsed because of secret explosive devices planted in the buildings and ignited by the airplanes that were flown into them linger among some. A nationwide survey by the Scripps Survey Research Center at Ohio University this summer found that one-third of those interviewed thought the federal government either took part in the attacks or allowed them to happen.

The National Institute of Standards and Technology responded to the top 14 alternative theories published in scientific papers and on the Internet.

"We've gotten a number of calls and e-mails [from people] who heard the claims by some of the alternative theory groups," NIST spokesman Michael Newman said. "We thought with the fifth anniversary of 9/11, it was an appropriate time to address the claims."

The report answers questions like whether government scientists tested for explosives in the wreckage. "NIST did not test for the residue of these compounds in the steel," it said. NIST also said it did not investigate whether the towers' collapse was the result of a controlled demolition -- a leading theory among some witnesses and university scientists -- or whether explosive materials were present in the wreckage.

Those skeptical that jet-fuel fires alone could have toppled the towers point to puffs of smoke seen before each tower collapsed, to the speed of the collapse and to the color of molten metal steaming from the second tower before it collapsed.

NIST said during its three-year investigation with 200 technical experts that it did not study controlled demolition because there is evidence that the collapse began in the floors struck by the planes or that were on fire, and because it took more than an hour for the building collapses to begin. It further points to video evidence that the collapse went from top to bottom -- not the other way around.

Instead, NIST argues that the planes severely damaged support columns, dispersed jet fuel and dislodged fireproofing insulation. "People say the temperature never got hot enough to melt steel," Newman said. "We never say 'melted,' but we say the temperature reached by the fires made it lose its integrity by 50 percent."

Newman said the reason the molten metal flowing from the second tower was yellow and not silver was because other metals mixed into the aluminum.

"Has NIST melted aluminum and then added the expected organic materials to form streams of falling, uniformly yellow solution?" asked Kevin Ryan, who co-edits Journal Of 9/11 Studies. He said the latest NIST report raises even more questions than it answers.

NIST said the report comes after criticism its 10,000-page October 2005 report did not directly address whether explosives toppled the towers. "We definitely stand behind the findings and conclusions of the investigation," Newman said.