Sunday, August 9, 2020

The Nature of Evidence

In my daily professional life I am an experimental particle physicist. I currently analyze data taken with the ATLAS detector on the Large Hadron Collider at CERN laboratory near Geneva, Switzerland. I probe data that includes collisions of billions of protons to look for patterns that indicate the existence of some unknown phenomena or that measure the properties of a particular physical process. I am currently studying the Higgs Boson that was discovered in 2012 and measuring certain aspects of its character to try to understand if it exactly fits our expectations or whether there may be deviations from our standard model. 

In my personal life I have twice been a member of a jury in both criminal and civil cases. As a juror, I was asked to analyze data presented by witnesses and experts to determine the probability that an event in the past occurred in a certain way. Both my profession as a scientist and my civil duty as a juror required me to examine evidence and draw the most logical and reasonable conclusions based on the evidence. However, the type of evidence available in the different circumstances have very different natures. 

There are some people I talk with, primarily religious skeptics, who don't seem to understand the difference between scientific data and legal/historical evidence; the data from a scientific experiment that allows the investigator to draw reasonable conclusions, and the evidence presented in a courtroom that also leads to reasonable conclusions about what occurred in the past. These data are of a very different type but both lead to reasonably certain conclusions. Scientific data cannot directly tell us what occurred in the past, for direct scientific inquiry requires reproducible experimental results. Past events are not reproducible. Legal historical evidence that is used in a courtroom consists of direct evidence and circumstantial, or indirect, evidence.