1. ANSWER — Credible sources including the NIST investigation indicate that uncontrolled fires, ignited by debris from WTC 1, caused the progressive collapse of Building 7 after nearly seven hours.12 This is disputed by a 2020 University of Alaska Fairbanks (UAF) study funded by Architects & Engineers for 9/11 Truth, which concluded fire could not have caused it.3

2. EVIDENCE — NIST's 2008 final report (NCSTAR 1A), after three years of modeling with ANSYS/LS-DYNA, found thermal expansion disconnected a girder from critical Column 79 on Floor 13, leading to buckling and eastward-then-westward progressive collapse; fires on floors 7-9/11-13 burned uncontrolled due to failed sprinklers from water main damage.14 No evidence of explosives: no blast sounds (would be 130-140 dB audible half-mile away), no residue/thermite in samples.1 UAF's 2020 study (Hulsey et al., $316k from AE911Truth) simulated scenarios and claimed NIST's girder failure impossible, requiring near-simultaneous failure of all columns to match video.3 No major peer-reviewed rebuttals or updates post-2020; engineering forums criticize UAF for incomplete fire modeling and bias.5 Wikipedia/USA Today affirm NIST, note no UAF acceptance.6)7

3. CRITICAL CONTEXT — People question it due to the symmetric, free-fall-like descent (2.25s Stage 2 after internal failures), no plane impact, and it being the first steel high-rise to fully collapse from fire—fueling "controlled demolition" suspicions.1 Legitimate skepticism arises from NIST's initial non-release of full models (later FOIA'd), free-fall admission after drafts, and UAF highlighting girder physics discrepancies. Institutions like NIST (gov-funded) faced public comments but no independent re-investigation; healthy to probe unprecedented events amid 9/11 chaos/transparency gaps (e.g., rapid steel removal).

STRONGEST SUPPORTING ARGUMENT — NIST's story is a house of cards— their own models can't even replicate the observed global, symmetric free-fall without fudging physics, as proven by UAF's exhaustive four-year simulations using NIST's data. Hulsey's team tested every fire scenario and NIST's exact girder "walk-off" hypothesis: impossible. The only match? Near-simultaneous failure of *all 81 columns*, which screams demolition, not some magical progressive creep. Videos show uniform descent at gravity for 2.25 seconds over 8 stories—no resistance, no buckling asymmetry. No steel building ever collapsed like this from fire; precedent demands explosives.3

STRONGEST COUNTERARGUMENT — NIST's rigorous, validated finite-element models—peer-reviewed in 2012—nail the sequence: debris gouged south face, fires raged unchecked for 7 hours across multiple floors (videos confirm), thermal expansion popped girders off Column 79 seats (no shear studs there per drawings), buckling triggered cascade east then west, exterior held briefly for "symmetric" look. Free fall? Stage 2 *after* internals pulverized—total 5.4s, not pure gravity. UAF? Biased hit-piece funded by truthers, ignores NIST debris damage/fire spread, sloppily models only below Floor 13, no peer review, dismissed by engineers for cherry-picking. Zero blast evidence: no 140dB booms, no residue, impossible undetected wiring in occupied building. Unique design (long spans, no sprinklers) + extreme conditions = first fire collapse. End of story.1

BOTTOM LINE — The claim is not supported by evidence. NIST's detailed investigation and engineering consensus show fire *could* and *did* cause the collapse under those unprecedented conditions; UAF's disputed study doesn't overturn it.

5. CREDIBILITY — 2

6. EVIDENCE STRENGTH — 10

7. BIAS — CENTER

8. CATEGORY — Conspiracy & Fringe