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

And yet, as terrible a thing that war, and the military institutions that support it, has been for humanity and the world-at-large, it remains a truth that many important discoveries have been made in pursuit of a better way to kill the guy on the other side of the battlefield. 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 scores of horrific wounds. World War 2 provided a huge boost to our understanding 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.

Here are four good things that we can thank war for.

Microwave popcorn
The microwave oven was invented just after World War 2 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 first demonstrated a 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 popcorn. It took a couple of decades for the microwave oven to find its way into middle class homes, but by the time it did, microwave popcorn was right there alongside.

Second Law of Thermodynamics
The laws of thermodynamics (there are four of them) are fundamental ideas that describe how temperature, energy, and entropy behave under different conditions. They are 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—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 entropic equilibrium, or when both blocks are the same temperature.

This fundamental law was developed by Nicolas Léonard Sadi Carnot, a French military engineer who has been called the “father of thermodynamics” for his contributions. He noticed that, in a thermodynamic system, like an engine, heat is always created (and lost) 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 lead to our more refined understanding of the second law of thermodynamics today.

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 cog in the complex system that is our modern world. Airlines rely on it to orchestrate their routes, shipping companies use it to track and manage their cargo, and I used it last week to find my way to a friend’s wedding.

GPS was built by the U.S. military upon a technological backbone that included systems they developed during World War 2. The military was 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 it to find our way around the world ever since.

Synthetic Rubber
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 2. By 1944, twice as much synthetic rubber was being made in U.S. factories as all of the 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 and hinges of medical equipment. We use it to make wet suits and spatulas, playgrounds and sporting equipment.

Main photo credit: Steven Depolo/Flickr; popcorn photo credit: Howard Cheng; thermodynamics graphic credit: アリオト; GPS photo credit: Guyver8400; rubber photo credit: The Car Spy