Monday 29 September 2008

Piggy hide and seek

Watching the 'freshers' turn up at work this year, all bubbly and full of the promise of a new beginning, made me have a little think. Eight years ago I was one of those over-eager little souls bounding into the Physics and Astronomy Department in Sheffield. Four years ago, I was probably not too dissimilar, this time bounding into the National Oceanography Centre, Southampton. Last week my PhD and, hopefully, Post-Doc supervisor handed me a book entitled 'Advances in Forensic Taphonomy: Method, Theory, and Archaeological Perspectives'. Funny how things change!

Were you to ask me where I thought I'd be in eight years time when I started my undergrad in Physics with Astronomy at Sheffield, I would almost certainly said something along the lines of 'hopefully doing something in astronomy'. Were you to ask me where I thought I'd be in four years time when I started doing geophysics at Southampton, I'd almost certainly have replied something along the lines of 'yeah, well, I'll probably sell out to the industry and go hunting for oil'. Yet, now, here I am, writing a Post-Doc proposal to play underwater hide and seek with some dead pigs using a variety of acoustic profilers. Funny thing is, I ain't complaining!

The principle is quite simple: we have already proved that our decimetre resolution 3D seismic system, 3D Chirp, can be used to image everything from geological structure on 10s metres scale, down to individual objects some 10s centimetres in size; and a number of companies have already shown that acoustics can be used to locate dead bodies. However Police authorities around the world still primarily default to using shore walks and diver surveys when conducting missing person searches.

To a large degree, their lack of trust in these new technologjes is reasonable. Practically, these systems tend to be highly specialised, requiring a large amount of detailed knowledge to get the best out of them. Thought needs to go into which acoustic profiler to use (side scan sonar, sector scanning sonar, echoscope, or a sub-bottom profiler such as chirp or boomer), where and how to use it, how to process the acquired data, how to interpret the processed data, etc, etc. The list is almost endless. Then, to confound it all, there has been very little work done on how the acoustic response of a body varies with the level of decomposition. How long does a body have to have been deceased before they present a strong enough acoustic signature to be detected? How long before the body is so decomposed that is presents no acoustic signature? How does this vary from person to person and locality to locality? How does this vary with the frequency content of the acoustic source? Such basic, fundamental questions need solid, scientifically robust answers before the Police authorities can be expected to make extensive use of these techniques. Hopefully, we might be able to provide them with a few.

Finally, something a little more topical. I recently discovered
this post by Moshe Rozali talking in very general terms about the principles of field theory, and in particular Quantum Gravity. This is a pretty meaty topic to tackle in any situation, but Peter manages it with beautiful elegance in his usual easy-to-read style. Given the recent media hype surrounding the LHC and the Higgs Boson, this post is well worth a read as it outlines some of the basic holes in our present understanding of gravity. Personally, I think it's a shame some of the 'science' journalists didn't give it a browse before they started the 'black hole to destroy the world' tirades, maybe we'd have gotten a few more interesting news reports if they had...although they would, probably, have sold fewer newspapers!

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