Week Five: Theory Never Matches Experiment

Share This:

Sunday, June 30, 2019


Joseph Tibbs

The title of this blog post probably set racing the hearts of any physicists reading it, and possibly put a smug smile on the face of any engineers.  The theorist and experimentalist are often seen as opposing forces in science: one’s work approximates what the other’s proclaims.  But which one does which job depends on whom you ask.  Do the equations theorists come up with approximate the reality which experiments can measure?  Or do experiments imperfectly reflect the ideal models put forth by theorists?

 I got the chance to experience both sides of that this week: after some successful AFM imaging, the data showed that the technique works in the way we expected.  To help explain just what was going on, I also simulated the operation of the AFM using the computational modeling software I’ve described in the past; the most recent and most accurate iteration of the simulations this week provided a graph of predicted voltage response.  When I called up the graph on MATLAB, I had to check my code to make sure I hadn’t just plotted the experimental data instead because, to a rough visual approximation, the two were indistinguishable.  Now, though this was exciting, it’s not exactly groundbreaking: we’re dealing with some very well-known properties of capacitance and potential difference.  But it’s still significant because it means the technique we’re developing can supply predictable, and hopefully reproducible, results.

 Some really fun things happened this week that I’d love to expand on: we went to a science trivia night hosted by some co-workers of Sammi at a local restaurant (with an excellent Taco Tuesday).  The ten of us sat at one long table, but ended up splitting into two teams.  There would be fifteen short-answer questions throughout the night, with bonus points awarded for the funniest (incorrect) answer.  We also got to name our teams; I was flattered to be the namesake for ours: Tibbs Free Energy.  For those of you who haven’t taken thermodynamics, Josiah Willard Gibbs was an incredible physicist who came up with a concept of free energy which was, eventually, named after him.  The questions were difficult, but our team answered enough of them correctly to end the first phase tied for first.  I would like to credit that success to my sister, without whose help I never would have known the name of the mission which sent the animals called Tardigrades (or water bears) into space. 

 But then came the second phase: the engineering challenge[d].  We had to use six uncooked pieces of spaghetti (I don’t think it was whole wheat), a plastic spoon, a popsicle stick, a dixie cup, and about four inches of duct tape to hold five marbles as high off the table as we could.  Using the spoon and stick as a load-bearing beam and the spaghettis as a stabilizing tripod, we made a structure which was (if I may say) the most stable of the assembled contraptions: we not only put the marbles into the cup, but filled it with water as well (making what was possibly the strangest mixed drink consumed that night).  Unfortunately, ours was not the tallest (who knew that a science trivia night would be populated by so many engineering-minded folks?) and we did not take home the trivia win.  But, we all agreed that we’d return for a rematch this week, especially upon hearing the theme: quantum physics.  They won’t know what hit ‘em. 

 Wednesday, we enjoyed the Congressional baseball game for charity.  This was an event I’d never heard of before coming to D.C., and now I wish I had: members of congress form two baseball teams (Democrats vs. Republicans, as per tradition) and play a nine-inning baseball game in the Washington Nationals Stadium.  Exhibiting there were companies, advocacy groups, and (our favorite table to get swag from) NASA.  I had heard that the Democratic team had won nine of the ten previous games; that got me wondering if political affiliation could possibly be correlated with baseball ability.  It didn’t seem to make sense in theory, but as the blue team racked up the points on Wednesday, I couldn’t help but wonder if controlled experiments would support such a relationship.  When all was said and done, I decided to dig deeper, and go to the most comprehensive storehouse of sports knowledge I know of: Wikipedia.  And there I found something which was highly satisfying, not to mention surprising.  To the best of historical knowledge, the 85-game series is now tied between the two teams: 42 wins to Democrats; 42 to Republicans; and one tie game, in 1983.  

 Cooking adventures continued this week, with breakfast foods accompanying a lively debate-watch party[5] and Bells’ delicious meat pies accompanying a different (but more appropriate, thematically) watch party on Saturday.  But rather than try to shoehorn some kind of theory-experiment duality into these anecdotes, I’m going to switch gears and discuss a different theme which was present this week, even if I was afraid to acknowledge it.  Yes, the end of this week, the fifth, marked the moment equidistant from the start and the end of this internship.

   The halfway point.

 Our lives are a set, or perhaps a series, of halves.  The horizon bisects the visual plane into earth and sky, and the temporal plane into day and night.  Not everything can be divided so cleanly in two: nature and nurture, theory and experiment, science and art.  These things blur the lines.  But if a midpoint does exist, it’s almost always special.  The vertex of a parabola is the apex of flight.  The center of gravity is the point that moves independently of any rotational torque on the object.  And the midpoint of an internship is a good time to look back and reflect.  It’s an apex in its own way: once it passes, the end will rush nearer faster each day.  Like Zeno’s Arrow, the halfway points will begin to fly by, each one dividing the remaining time into smaller and smaller increments.  Theory says an infinity of such increments will pass.  Experience tells me that they won’t amount to any more time than if I had chosen to simply enjoy the remaining weeks day by day.

 I don’t know what I expected from this summer—what I theorized.  But I know that trying to predict what will happen is an exercise in chaos theory and futility; it’s only a distraction from finding out the empirical way.  In other words, life is an experiment.  So, if you’ll excuse me, I’m off to experience what—I hope—may be the better half.  No matter what happens though, I know the five weeks I’ve had so far halve been some of the best of my life.

 And no, I’m not sorry.

 Joseph Tibbs

At Science Trivia night!  Props to "The Big Board" for hosting and for serving excellent tacos.
The congressional baseball game in the Washington Nationals Stadium
I got to visit the grave of Gibbs last summer, and I thought it was cool enough and relevant enough to put it here.

Joseph Tibbs