Riddle me this: why does dS = 0 for reversible, adiabatic expansion?

While attending an event in Syracuse, New York, I got to talking with an older chemical engineer who had once worked with my dad at Bristol-Myers Laboratories. I shared that I was writing a book on thermodynamics and we spoke some about this. At the conclusion, he looked at me and said, “You know, IContinue reading “Riddle me this: why does dS = 0 for reversible, adiabatic expansion?”

Thermodynamics: What is “heat”?

The word “heat” can be very confusing to those trying to learn and understand thermodynamics. I created this video (here) to help clarify things. I go into more detail about this topic and many others in my book Block by Block – The Historical and Theoretical Foundations of Thermodynamics.

Riddle me this: what is the physical significance of T∆S in Gibbs’ maximum work equation?

Remember this? Maximum work = -∆Grxn = -(∆Hrxn – T∆Srxn) At some point toward the end of undergraduate thermodynamics, we were taught this equation.  Unfortunately, most of us, myself included, graduated without actually understanding it.  Why?  You already know the answer, just by looking at it.  Because entropy is involved.  While many have a reasonableContinue reading “Riddle me this: what is the physical significance of T∆S in Gibbs’ maximum work equation?”

Like a Bird – Flying Balloons on Other Planets

* * * For this post I invited back fellow thermodynamics enthusiast Mike Pauken, principal engineer at NASA’s Jet Propulsion Laboratory and author of Thermodynamics for Dummies, to complete this 3-part series related to his work on developing balloons for Venus. His first post covered the developmental history of balloons while his second dove into the fundamental reasonsContinue reading “Like a Bird – Flying Balloons on Other Planets”

Riddle me this: why does a gas deviate from ideal behavior?

Years ago, during on-campus interview season at college, a friend of mine majoring in electrical engineering told of how difficult one of his interviews was.  “The interviewer asked me how an oscilloscope worked, and I carefully explained how to plug in the different wires and then how to adjust the knobs and so on.  HeContinue reading “Riddle me this: why does a gas deviate from ideal behavior?”

Why Do Balloons Float?

An experimental balloon takes its inaugural flight in August 2020. This particular balloon can change altitude by shortening or lengthening a cord attached the top and bottom of the balloon. Shortening the cord compresses the balloon which makes it descend while lengthening the cord expands the balloon allowing it to ascend. Photo courtesy of ThinContinue reading “Why Do Balloons Float?”

How to conduct powerful science? Check your ego at the door.

Observe nature, take measurements, and then propose as many hypotheses as you possibly can that are consistent with the data. In this way, you shift the focus from a negative conflict between scientists, each embracing their own individual hypothesis, to a positive, exciting, and team-based conflict between ideas in which technical debate among those with differing perspectives is encouraged in order to learn and not to win.

Carrying the Dreams of the Montgolfier Brothers to Other Worlds

Balloons – Early Thermodynamics Machines A team of JPL engineers tests whether a large balloon can measure earthquakes from the air. The team proposes to measure “Venus-quakes” from the upper atmosphere of Venus, using an armada of balloons. The author is on the left holding a fan to inflate the solar balloon. Image Credit: NASA/JPL-CaltechContinue reading “Carrying the Dreams of the Montgolfier Brothers to Other Worlds”

Electric Cars – Is “zero emissions” a valid claim?

I just read an article about an electric vehicle having zero CO2 emissions and thought it’d be an opportune moment to emphasize the value of thermodynamics in critically assessing such claims. Let’s walk through how this is done, starting first with a recap of the foundational mass & energy conservation laws. The conservation laws forContinue reading “Electric Cars – Is “zero emissions” a valid claim?”

Happy birthday, Henrietta Leavitt!

You’ve likely heard of the Big Bang theory and the name of Edwin Hubble associated with it. But a person you may not have heard of is Henrietta Leavitt. Leavitt played a critical role in enabling Hubble’s accomplishment. Seeing as today’s her birthday, let’s celebrate her, her achievement, and her impact on astronomy and cosmology.Continue reading “Happy birthday, Henrietta Leavitt!”