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Arson Science Rewritten
An anonymous reader handed us a link to an AP story about advances in the science of arson investigation. Many assumptions about fire, long held by investigators, have been overturned in recent years as scientists have come to understand concepts like 'flashover'. The repercussions of these findings is having an effect not unlike the use of DNA in crime-solving; people are being set free, and old cases are being re-examined. From the article: "Significantly, flashover can create very hot and very fast-moving fires. And it can occur within just a few minutes, dashing the concept that only arson fires fueled by accelerants can quickly rage out of control. The studies began to chip away at the old beliefs -- critics call them myths -- but it took years. Through the 1980s, texts at the National Fire Academy in Emmitsburg, Md., still taught the traditional techniques. It wasn't until 1992, when a guide to fire investigations by the National Fire Protection Association -- 'NFPA921: Guide for Fire and Explosion Investigations' -- clearly laid out, in a document relied upon by authorities nationwide, that the earlier beliefs were wrong."
Its also interesting that flash over may not be confined to restricted sapces like rooms. I have heard of similar effects occuring in the late 1960's in a very hot eucalypt fire. The gases boiling out from the eucalypt fire were trapped by an air inversion until eventualy the whole valley ignited and erupted in a ball of flame.
After something like 40 years of this being accepted, someone actually tested it. Result: no freaking correlation at all. The variation in composition of bullets within a given box was the same as variation among bullets from different boxes, purchased years apart. This is a completely worthless forensic technique.
Or consider early DNA testing. Up until at least the mid '90s (I don't know what they do now) a DNA test only looked for matches at a small number of base pairs. For any given DNA sample tested, there would be thousands of people in the world that matches that sample. What this meant was the the scientifically correct way to use DNA testing was to find your suspects using traditional police techniques, and THEN use a DNA test. If you had, say, 3 good suspects, and one of them had a DNA match, then that was very good evidence against that suspect. Unfortunately, sometimes it was used the other way. They'd start with the DNA, match it against whatever samples they had on file, and if they got a match, they'd go after that person. That's bogus.
If you look into the science behind much police investigation, you get this strange feeling you've fallen through some kind of wormhole and gone back to the early 19th century. It's amazing how much in common use has not been rigorously tested and peer reviewed by real scientists.
Many of you across the pond won't be familiar with this disaster, but it's as good an example of fire spreading quickly without accelerants as you'll ever see. It all started when someone dropped a cigarette, and within a few minutes a hundred-metre long wooden stand was a goner, killing dozens of people. There's a video of it on YouTube, although I should warn you that there's one or two scenes in it which I personally find slightly difficult to watch.
I wonder why my European parents have a wooden house (wooden frame filled with stone wool and covered with wooden planks, built in 1998), why their neighbours save one have also wooden frame houses, the oldest one being from 1654 (yeah, that's more than 350 years ago), why 25% of Germany's area is covered by forests, why Europe is in fact increasing its forest area, why towns like Quedlinburg or Erfurt are declared UNESCO cultural inheritance for their timber frame town centres, where all those pittoresce Black Forest and Bavarian rural houses come from, why we talk about "balconies" (which is just the german word Balken = timber).
Wood is a very common material in residential construction in Germany, and in fact its usage has increased with the larger number of prebuilt houses being built here.