Einstein’s Fridge: How the Difference Between Hot and Cold Explains the Universe by Paul SenEinstein’s Fridge: How the Difference Between Hot and Cold Explains the Universe by Paul SenEinstein’s Fridge: How the Difference Between Hot and Cold Explains the Universe by Paul Sen

At some point in your schooling you learned the Laws of Thermodynamics. And then, at some point shortly thereafter (or at least, shortly after the test on them), you promptly forgot them. And even if you later in life you kept up with reading about science, well, there was always something sexier to read about: black holes, new particles, rovers zipping around on Mars. But in Einstein’s Fridge: How the Difference Between Hot and Cold Explains the Universe (2021), Paul Sen is here to argue thermodynamics deserves both your attention and your respect, seeing as how it lies at the foundation of just about all our technological advancement. And darn if he doesn’t make the case.

On the one hand, the Laws (Sen really focuses mainly on the first two), are pretty simple to formulate: energy can never be created or destroyed but is always conserved and the entropy of the universe is always increasing. But while the words are simple, learning why those things are true was fiendishly difficult. And explaining it so non-scientists understand it (as any high school physics teacher will attest) isn’t much better. But while it took a host of curious and brilliant people (including well known luminaries like Maxwell, Einstein, Turing, and Hawking) centuries to do the former, Sen takes just over 200 pages to do the latter and do it supremely well.

Einstein’s Fridge: How the Difference Between Hot and Cold Explains the Universe by Paul SenSen begins in Britain in the early 1800s with Sadi Carnot, who despite dying tragically at age 36, is known as “the founding father of the science of thermodynamics.” From there, Sen methodically and clearly marches through time and science as one discovery after another furthers human knowledge of heat, entropy, and the basic underpinnings of the universe. It’s also a walk through technological progress, from steam engines to internal combustion engines to that titular home appliance (and yes, Einstein did form a business to design better and safer refrigerators) to the transistor and the silicon computer chip. One of the more interesting aspects of Einstein’s Fridge is how the technological advancements often came prior to understanding the underlying scientific fundamentals, and often raised the questions that provoked study of the basic science that allowed for the technology to work.

The narrative is never anything but crystal clear, with Sen lucidly and carefully laying out the science, aided by a number of greatly appreciated illustrations. He also makes frequent use of analogies to make the unfamiliar and esoteric more familiar and grounded in something easier to understand, a typical tool in popular science books. Here, though, things are a bit of a mixed bag. While many of the analogies helped illuminate their subjects, a few I thought were actually a bit muddy, leaving me wondering if that made things more complicated than simpler. Meanwhile, the thumbnail sketches of the many important figures such as the aforementioned household names, along with others such as Kelvin, Joule, Helmholtz and others are concise but engaging and at times even moving, as with the tragic early death of Carnot, or the suicides of Bernoulli and Turing.

Einstein’s Fridge is wonderfully clear, winningly concise, peppered with interesting personal stories, and leaves you knowing more about its topic than you did going in. Not that you should feel too bad about how little you knew at the start, given that Sen closes with a story of how even Stephen Hawking got thermodynamics wrong. So maybe the rest of us can be forgiven for needing just the book Sen provides us.

Published in March 2021. An entertaining, eye-opening account of the extraordinary team of innovators who discovered the laws of thermodynamics essential to understanding the world today—from refrigeration and jet engines to calorie counting and global warming—for fans of How We Got to Now and A Short History of Nearly Everything. Einstein’s Fridge tells the incredible epic story of the scientists who, over two centuries, harnessed the power of heat and ice and formulated a theory essential to comprehending our universe. Thermodynamics—the branch of physics that deals with energy and entropy—is the least known and yet most consequential of all the sciences. It governs everything from the behavior of living cells to the black hole at the center of our galaxy. Not only that, but thermodynamics explains why we must eat and breathe, how lights turn on, the limits of computing, and how the universe will end. The brilliant people who decoded its laws came from every branch of the sciences; they were engineers, physicists, chemists, biologists, cosmologists, and mathematicians. From French military engineer and physicist Sadi Carnot to Lord Kelvin, James Joule, Albert Einstein, Emmy Noether, Alan Turing, and Stephen Hawking, author Paul Sen introduces us to all of the players who passed the baton of scientific progress through time and across nations. Incredibly driven and idealistic, these brave pioneers performed groundbreaking work often in the face of torment and tragedy. Their discoveries helped create the modern world and transformed every branch of science, from biology to cosmology. Einstein’s Fridge brings to life one of the most important scientific revolutions of all time and captures the thrill of discovery and the power of scientific progress to shape the course of history.


  • Bill Capossere

    BILL CAPOSSERE, who's been with us since June 2007, lives in Rochester NY, where he is an English adjunct by day and a writer by night. His essays and stories have appeared in Colorado Review, Rosebud, Alaska Quarterly, and other literary journals, along with a few anthologies, and been recognized in the "Notable Essays" section of Best American Essays. His children's work has appeared in several magazines, while his plays have been given stage readings at GEVA Theatre and Bristol Valley Playhouse. When he's not writing, reading, reviewing, or teaching, he can usually be found with his wife and son on the frisbee golf course or the ultimate frisbee field.

    View all posts