War is hell. Nations can wreak enormous destruction over the landscape when they hurl their armies at one another. Towns and cities can be destroyed, entire ecosystems can be ripped apart, and untold misery can be piled up on any human fortunate enough to survive the fighting.

And yet, as terrible the effects that war has had on humanity and the world at large, many important discoveries have been made in pursuit of a better way to kill the guy on the other side. A lot of medical innovations arose from the carnage of the American Civil War as doctors searched for ways to fight infection and successfully treat horrific wounds. World War II gave a huge boost to the world of physics as some of the world's richest nations poured rivers of money into splitting the atom. That same war provided a similar boost to research into computers as many of the field's top minds threw themselves into projects like cracking the German's secret Enigma code.

For better or for worse, here are four good things that we can thank war for.

Microwave popcorn

Microwave popcorn

Photo: Wikimedia Commons

The microwave oven was invented just after WWII when engineer Percy Spencer noticed that a chocolate bar had melted in his pocket after he stood in front of a magnetron, a piece of equipment used in radar. Modern-day radar can be traced back to American Robert M. Page, who was working for the Navy when he demonstrated his working model in 1934. Radar was further fined throughout the war to the point when Spencer made his discovery. One of the first foods that Spencer tried heating by microwave was the popcorn. It took a couple of decades for the microwave oven to find its way into middle-class homes, but when it did, a microwave popcorn craze was born. (We've since learned that there's a less mouth-watering side to microwave popcorn, but that's not part of today's history lesson.)

Second Law of Thermodynamics

Cannon

Photo: Wikimedia Commons

The laws of thermodynamics (there are four of them) are fundamental ideas that describe how temperature, energy, and entropy behave under different conditions. They form the base of much of our understanding of how things work while operating quietly all around us.

The second law of thermodynamics states that temperature, pressure, and chemical potential tend to equalize towards entropy in systems not in thermal equilibrium — or more simply, put a hot block of wood next to a warm block of wood and the heat will move from the hot block to the warm as the system trends towards equilibrium, or when both blocks are the same temperature.

The groundwork for this fundamental law was laid by Nicolas Léonard Sadi Carnot, a French military engineer who has been called the "father of thermodynamics" for his contributions to our understanding the field. He noticed that, in a thermodynamic system, heat is always created in the process. That heat represents the energy that transitioned from a higher state of order (when it was trapped as fuel) to a lower state (the heat). He found the process to be irreversible and formalized it into writings that led to our more refined understanding of thermodynamics today.

Cannon fire demonstrates the idea that energy tends to evolve to a state of maximum entropy: energy moves from forms of high concentration, like gun powder, to forms of low concentration, like heat.

GPS

GPS satellite

Photo: Wikimedia Commons

The Global Positioning System, better known as GPS, is made up of a network of satellites sitting in geosynchronous orbit around the Earth and allows users to accurately pinpoint their location using compatible devices. GPS has become an indispensable part of our modern world. Airlines rely on it to orchestrate their routes, shipping companies use it to track and manage their cargo, and I certainly used it to find my way to a friend's wedding recently.

GPS was built by the U.S. military on a tech backbone that included systems developed during World War II. The military had been experimenting and using satellites for navigation since the '60s. In 1994, the 24th satellite of the first GPS system available to civilians was launched and we've been using GPS to find our way around the world ever since.

Synthetic rubber

Rubber tires

Photo: Wikimedia Commons

The world's cars ride on a sea of synthetic rubber. Every tire in the world is made using one form of synthetic rubber or another, a technology that developed by Allied scientists during World War II. By 1944, twice as much synthetic rubber was being made in U.S. factories were making twice as much synthetic rubber as the entire world's pre-war production of natural rubber (made by processing sap from the rubber tree). By the end of the war, synthetic rubber was the go-to material for tires.

The use of synthetic rubber permeates our lives today and can be seen in the nose pads of eye glasses and in the hinges of medical equipment. We use it to make wetsuits and spatulas, playgrounds and sporting equipment.

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