Anatomy of an Experiment I - The Question

Warning: picture has little or no relation to this post.

I realized the other day that I've seen a lot of people talk about research results, but it is much more rare that I see someone talk about how we do research.  I think that may be because, to us as scientists, the process is second nature.  We've been doing it for years.  Other folks may be less familiar with the process though.  With this in mind, I'm going to do a short series of posts focused on how we do an experiment.  Not the results, not so much the physics, but the process that we go through to create, setup, and carry out an experiment.  As my example I'll use a short little experiment that I built from the ground up in the last few weeks, that I'm currently in the process of (hopefully) wrapping up.  Today I'll talk about the driving force behind almost any experiment: The Question.

Steak Dinner

Sorry about the blog hiatus. During the summer, without teaching classes, inspiration is harder to come by. But, tonight I cooked a steak. I recently got a new digital meat thermometer. My plan was to slowly cook the steak until the internal temperature got to be about 140 degrees Fahrenheit with the oven at 200 degrees, take it out, wrap in tin foil, crank the oven to 500 degrees, stick it back in, and give it a nice exterior, reaching an internal temperature of about 150 degrees which would put it at about medium.

After I put the steak into the oven though, I started to watch the temperature go up on my digital thermometer and thought, why not take data. And so I did. Here are the results.

Above you see the internal temperature of the steak as a function of time. First some comments about the graph.

Life as an Experimenter - Reflections

I've been doing experimental physics for about three years.  I started during my sophomore year in college, went straight to graduate school, and continued here (albeit not quite immediately).  There are people out there who have been doing this for a lot longer than I have, but I've gained a few insights, by working with said people, and through my own experiences in the lab.  I thought I'd try to share a few of these, to help illuminate the past few days I blogged about.

Life as an Experimenter - Day Three

Today marks the third and final day in our beam time at CHESS.  I think the circles under all of our eyes may take away from the glamor a bit, but the right makeup specialist could fix that.  If they ever make a movie about us, which they should, I want to be played by some really awesome british actor.  I think that would be about right.  Someone with a strong jaw.  In case it's not obvious, lack of sleep is getting to me a little bit.  Read on for the final few hours of our experiment.

Life as an Experimenter - Day Two

Today I'm continuing my series on the life of an experimenter.  Today is the longest day, since we have beam time for all 24 hours.  And after the setbacks of yesterday, we feel compelled to use it to the utmost bit.  Read on for more tantalizing glimpses of the grit behind the glamor of the rock-star-like lifestyle of an experimental physicist.

Life as an Experimenter - Day One

I'm an experimental physicist.  If you think this sounds like a job second in glamour only to rock star you would be right.  Just like being a rock star, you have to deal with the people, the shows, the lights, the groupies . . . okay, maybe I'm lying about the groupies.  Unless you're Brian Greene.  Also similar to a rock star, no one really knows what it is we do behind the scenes (when we're not touring the nation or publishing papers).  I'd like to pull back that curtain a little bit.

Letting Air Out of Tires II

In a recent post I calculated how cold air coming out of bike tires should feel.  However, at the end of the post, I did note that there are competing explanations for why the air cools.  There's the approach I took, which is adiabatic cooling, but there's also something called the Joule-Thomson effect.  The Joule-Thomson effect has the interesting property that helium being let out of a bike tire would actually be warmer, which suggests an immediate way to test which effect is dominant.  We pressurize a bike tire with helium, and see if the valve gets cold or hot.  This is exactly what I did.

Letting Air Out of Tires

Have you ever noticed how when you let air out of a bike tire (or, I suppose, a car tire) it feels rather cold?  Today we're going to explore why that is, and just how cold it is.  Many people consider the air escaping from a tire as a classic example of an adiabatic process.  What is an adiabatic process?  It is a process that happens so quickly there is no time for heat flow to occur.  For our air in the bike tire this means we're letting it out of the tire so quickly that no energy can move into it from the surrounding air.