Arson Science Rewritten 152
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."
If you've ever seen how fast a fire moves... (Score:5, Insightful)
I know there was a case a few years ago where an "arsonist" in TX was executed for having killed his family, and within less than a year it was established that he was innocent.
I'll just say, the idea of someone being executed based on expert testimony from arson investigators, who are not even scientists, is appalling. Experts are only right until some new piece of knowledge comes along and changes the field.
Re:Hmmm, Not in my training and experience (Score:3, Insightful)
That comment made me think, I've heard it countless times on TV shows etc. Right now I just thought about how many times I've burnt my fingers holding a lit match.
Re:Wooden houses? (Score:3, Insightful)
Besides, what is going to hold up your concrete second floor? Or is it that all houses in your country have no cellars or second floors? The cost of constructing a house made entirely of mortar, brick, and stone is immense. Thus, wooden houses.
In the ideal world, nothing burns. In the real world, even concrete and steel give under fire.
In the ideal world, concrete and metal buildings are as inexpensive as wood. In the real world, this just isn't so.
In Mother Russia, the concrete burns you!
-jbevren
Re:Wooden houses? (Score:5, Insightful)
Basically Europe is completely deforested. There are forests, sure, but they would be gone pretty quickly if people started building homes out of wood.
As for the engineering aspects - concrete is strong and you can easily drop a concrete slab as the floor on your second story if you use walls of reasonable thickness - or you can use wood flooring suspended on a central beam(s) or one of dozens of other ways that builders use to suspend a floor in a wood house. Very few houses in Europe are only 1 story.
I've seen pre-fabed buildings being put together (and quickly) in Poland and Eastern Europe using both methods - a crane, a few hours and a welder is all it takes to get the structure done since the buildings come on the truck with rebar in place, holes and supports already in the concrete. Pretty cool actually.
Assembling a house out of brick isn't terribly difficult either - many people in Eastern Europe build their own houses, by hand, slowly, after they come back from their day jobs or whatever. Try doing that with wood construction and you'll end up with a crooked house that falls down in a year.
There is also a newer technology under the category of "insulated concrete forms" (ICF) - basically big hollow styrofoam blocks that you assemble like legos and fill with concrete (they have internal structure and rebar holding them together)
A house built with ICF has superior insulating properties (and does a fair job of blocking wifi signals too
Re:If you've ever seen how fast a fire moves... (Score:5, Insightful)
Re:If you've ever seen how fast a fire moves... (Score:5, Insightful)
What you didn't mention is that new evidence can come along and solidify a field. Just because the scientific method can disprove preconceived theories doesn't negate the power of science, which is what I read that you are implying. At least toward evidence for a death penalty, but if you believe that you cannot rely on science then what can you rely upon?
Re:lots of junk science in police work (Score:5, Insightful)
Things can get tricky here. It can be a bit like sculpture, in a way- if you chisel your evidence just the right way, maybe it'll look like what you want. That can be a very bad thing. However, some investigations require tailor-made tests; I can think of a couple instances- none of which had anything to do with trying the accused, fortunately- that I was called upon to create a test or an experiment that produced results that could be used to determine an association. For example, when the accused was found with certain components, I was asked to determine if those components could be used to detonate a certain kind of bomb. They weren't used in the trial, but they were used to hold the suspect in pre-9/11 America when you had to prove that sort of thing.
Some tests rely upon the odds of producing a match- as with fingerprints. However, these are not always reliable. [wikipedia.org] That's biometrics, with a long and sometimes dubious track record. I'm not even sure if there's been a paper in the refereed literature that cites the statistics on the likelihood of a match between two non-related prints given a certain number of features.
Other fields, such as firearms and toolmarks, are even more open to interpretation. DNA evidence is a little better in some regards, but these figures have been botched, too- sometimes with lab accidents, sometimes intentionally. Fortunately, standards have gotten a lot tighter, and DNA evidence has been used to exonerate a considerable number of the accused, including a distressing number of individuals on death row.
Fortunately, some are straightforward. While that field test for, say, cocaine might give a false positive for several hundred (or thousand) compounds, the Raman infrared spectrometer can tell you what it is, even through the polyethylene bag in which the sample is kept. Then another test- gas chromatography or gas chrom with a mass spec detector (GC/MS) is used to confirm. The chemistry side of it is pretty good, provided orthogonal analysis- two independent tests based on different principles of analysis- can demonstrate that the sample has been identified correctly.
Re:Wooden houses? (Score:2, Insightful)
Bert
Re:If you've ever seen how fast a fire moves... (Score:5, Insightful)
What it appears he's saying is that, given that long-held scientific beliefs can and are overturned but killing someone cannot be overturned, perhaps scientific evidence isn't enough to justify killing someone who isn't presenting an immediate threat.
Re:If you've ever seen how fast a fire moves... (Score:3, Insightful)
Re:If you've ever seen how fast a fire moves... (Score:3, Insightful)
On the other hand, you're right. While there are a few cases of people on death row being proven innocent, and many more cases of death row inmates having their sentence commuted, there has never been a case of significant evidence coming to light of an inmates innocence after he had already been executed. This is largely due to the massive appeal process which every death row inmate goes through.
Re:If you've ever seen how fast a fire moves... (Score:3, Insightful)