Sunday, September 13, 2020

Minimizing Bias in Experimental Particle Physics

The experiments at the Large Hadron Collider at CERN produce a total of about 90 petabytes of data per year. A relatively high-end desktop computer today may have a disk that can store about 1 terabyte of data, which means it takes the disk space of about 100,000 desktop computers to store the annual data collected by the CERN LHC experiments. The physics researchers who work at CERN use powerful computers to analyze this data. The goal of our analysis is always to learn more about the fundamental structure of the universe. We are particularly trying to probe aspects of nature that we do not yet fully understand and discover something that we do not yet know.
In very general terms, the analysis of our data can be divided into two very broad categories. The first category could be labeled "measurements" where we try to more precisely measure the value of some property of nature that we have already observed and for which we have a mathematical model that predicts what the measurement should reveal. If the measurements differ from expectations, then we have indirectly discovered something about nature previously unknown. The second category could be labeled "searches" where we actually search directly for a new undiscovered particle or a new undiscovered phenomena. Often, we are searching for something predicted by some proposed model of physics developed by a theoretical physicist. 

When looking for new phenomena it is vital that we do not introduce presuppositional ideas or bias into our experiments. It is well documented that human bias can subconsciously skew the experimental analysis. In my last blog post I mentioned that, "we go to great lengths to minimize any bias toward one conclusion or another, particularly when looking for some unknown phenomena or particle." A reader of my blog, Keith, asked a number of questions about how we minimize bias in our experiments.  The lengths we go to and the methods we use are quite informative and can have applications to other arenas in life where we want to come to some objective conclusions.

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. 

Sunday, July 12, 2020

The Logic of Christianity and Grace

As a professor of physics I will often work with undergraduate students and graduate students who are just learning the process of analyzing complex data from a high energy physics experiment. The students will show me graphs they have made and sometimes, with a relatively brief look at the graphs, I will know that the student has made a mistake somewhere in their analysis. There are a few ways that an obvious mistake may present itself. Some distributions should have a known shape and a major deviation from that expectation indicates a problem. If the results from different plots contradict each other then something must be wrong somewhere. Consistency across different data sets and different parameters is essential for a properly implemented analysis.

As a Christian who wants to know the truth, I have also analyzed the message and worldview of Christianity to see if it is consistent. If Christian doctrine contained actual logical contradictions, that would be an indication that Christianity has problems and is likely not true. Although I sometimes encounter people who think that the message of Christianity is contradictory, I usually find that those people have an incorrect view of the what is actually believed by Christians who are grounded in biblical doctrine. 

Saturday, June 20, 2020

Sabbaticals, New Ideas, COVID, and The Good Place

It has been almost six months since I have written and posted anything on my blog. Thanks to many of you, my readers, who have sent me inquiries as to the reason why my blog has been dormant, expressing your appreciation for the content, and asking if, and when, I will be writing posts again. I really appreciate all the kind remarks so many of you have sent me over the last few months. 

First, I should say that I don't really have any unusual or profound reason for the drought of blog posts. After writing at least two posts per month for three years, I simply have fewer new ideas for what to write about and, therefore, less motivation to write, since so many of my ideas that relate science, reason, and logic, to Christianity have already been addressed in previous blog posts. In addition, as with any activity that is done for a long period of time, I had simply become a little fatigued with writing new posts week after week. I am a university professor and, in academics, professors are allowed to apply for a sabbatical every seven years in which they take a semester or two off from teaching in order to focus on research and creative activity and to generate new ideas and revitalize their creative endeavors. From my perspective as a professor then, maybe I just needed a short sabbatical from my blog activities to gain a revitalized perspective. I still am not sure what new thoughts and ideas I have to add to the many blog posts I have written over the last few years, but I will at least try to get back into the pattern of writing on a regular basis. As such, I appreciate any thoughts my readers may have on topics that could be addressed in this blog. 

As with so many people in the world right now, I have spent the last three months or so fairly sequestered in my house. Because my research is based at CERN laboratory in Geneva, Switzerland, but I live in Oklahoma and teach at the University of Oklahoma, my daily routine even before the COVID-19 pandemic consisted of spending a lot of time in video meetings and looking at data from the Large Hadron Collider using my local computer. So, actually my professional life lately while working from home has been quite similar to my professional life when working from the university buildings: writing and running computer code to analyze data and meeting with people and groups by video. However, my personal life has changed quite dramatically over the last few months. I have spent more time cooking at home and more time streaming video at home. 

My wife and I have watched more content from Netflix, Prime, Disney+ and other services than I ever thought I would in such a short time. And some of the content I have watched has even generated a few ideas for my blog. We have just finished watching all four seasons of the NBC show, The Good Place, and some of the themes and ideas explored in that show are pertinent to both physics and Christian thought. If you haven't seen the show I should warn you now that the rest of this post is full of spoilers. So if you don't want spoilers for The Good Place, you probably should stop reading now.