Thursday, September 2, 2010

Risk and Uncertainty Road Show begins!

We've just kicked off a series of cross campus discussions with a great visit to the Physics department at UNL. 'We' in this case refers to Sarah Michaels (Political Science), Richard Rebarber (Mathematics), our able graduate assistant Adam Schapaugh (School of Natural Resources), and myself. The Risk and Uncertainty Roadshow is funded by an interdisciplinary seed grant from the College of Arts and Sciences at UNL. Our goal is to visit 10 departments and ask them what the concepts of Risk, Uncertainty, and Critical Thresholds mean in the context of their discipline's theoretical and empirical approaches.

We couldn't have asked for a better kickoff to the project; our hosts were active and involved participants who gave us no chance to mess up - they led the discussion themselves by and large! Here's a brief, shoot from the hip synopsis of the main ideas we took away with us - a more thorough writeup will follow based on the copious notes taken by Adam during the session.

So the obvious - in hindsight - statement took about 30 seconds to appear - the Heisenberg uncertainty principle is bedrock, settled science, and a fundamental source of uncertainty for physics. While there was total consensus on this, there was plenty of diverse opinions about what the principle actually means for a practicing physicist. Beyond that, there was also fairly broad consensus on three other sources of uncertainty - measurement error, systematic error, and the uncertainty created by using an approximation to represent reality. While statistics and probability are clearly the tools for dealing with measurement error, it was clear that systematic error and "approximation error" were less easy to quantify - hopeful guesses.

While there was rapid and wide ranging discussion of uncertainty with a great deal of consensus on the terms and concepts, risk was more difficult. The main idea, expressed a couple different ways, is that risk involves an expectation of harm - the product of a probability of an event occurring, and the magnitude of how bad that event is. There was agreement that whether an event is "bad" or not depends on who you talk to - different people may weight the same outcome differently. And all agreed that driving a car was the most dangerous thing one can do - much worse than the common perception that flying and nuclear energy are risk prone endeavors.

In many respects this bit was the most interesting for me personally. Our physics colleagues identified two broad features of a dynamic system that would lead to a "threshold". The first is that there is a qualitative change in the behavior of the system following a perturbation, or shift, in the parameters. On macro scales this change may appear discontinuous, but viewed at sufficiently fine scales the change is always continuous and smooth albeit rapid and not linear. The second feature generated a bit more discussion - the idea that the change is "irreversible" in some sense. For example, a spring can be loaded with more and more weight, and it will continue to function as a spring. However, at some point the spring breaks and behaves in a qualitatively different fashion, and this change is not reversible. What constitutes a reversible change seems to be open for discussion - phase transitions in matter (e.g. from solid to liquid) were offered as an example of a qualitative change in behavior that is reversible, although only by adding or removing energy.

Overall it was a great discussion. I'm excited about the rest of our visits to come. Stay tuned for more reports of future discussions, and information on the times and locations if you're local enough to drop in for a listen.

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