The Fertile Soil of Pre-WWII Technology: Why Tech Became the New Weapon of War

Imagine you’re standing on a foggy English coast at 2 a.m. in February 1935. The wind whips your coat, and the only light comes from a flickering lighthouse 15 kilometers offshore. You can’t see or hear anything in the sky, but the scientist next to you is grinning as he scribbles furiously on a notepad: a metal plane carrying 500 kilograms of bombs is flying straight for London, and he just proved it using nothing but invisible radio waves. That night marked the first successful test of radio-based aircraft detection—what we now call radar—and it was the opening shot of the World War II tech race.

For the 20 years between the end of World War I (1918) and the start of World War II (1939), the world looked calm on the surface. The Roaring Twenties brought jazz, flying boats, and the first commercial radio broadcasts. The Great Depression of the 1930s brought poverty and political unrest, but most people still thought another large-scale war was impossible. Behind the scenes, though, scientists, engineers, and military leaders across 5 major powers (the United Kingdom, the United States, Germany, Japan, and the Soviet Union) were building the tools that would decide the outcome of the deadliest conflict in human history. This chapter will pull back the curtain on that “fertile soil” of pre-war technology, explaining how curiosity-driven science in the 1920s and 1930s turned into the new weapons of war.

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The Shadow of the Last War: Why Nations Bet on Tech

World War I was fought in muddy trenches, with soldiers charging across no man’s land under machine gun fire. More than 31 million people were killed or wounded, and most military leaders agreed: the next war would not be won by charging infantry. It would be won by new technology that could strike faster, farther, and more accurately than ever before.

The problem was, in 1918, almost none of the technology that would define WWII existed yet. Airplanes were still made of wood and canvas, carrying a single rifle for the pilot. Radios were bulky, short-range devices used only for sending Morse code messages. No one had ever split an atom, and the fastest plane in the world could only fly 230 kilometers per hour—slower than many modern cars.

So the 20 years between the wars became a global, secret race to turn the wild scientific ideas of the early 1900s into real weapons. Nations poured money into research labs, hired the smartest scientists they could find, and tested hundreds of crazy ideas—some of which worked, and some of which exploded (sometimes literally). To understand why WWII became a tech race, we first need to understand the three big scientific breakthroughs that made all the new weapons possible.

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The Three Pillars of Pre-War Science

Every weapon developed during WWII grew out of three fields of research that exploded in the 1920s and 1930s: radio physics, atomic physics, and aerospace engineering. None of these fields were originally created for war—they were driven by scientists’ curiosity about how the world works. But when war came, they became the foundation of the entire conflict.

Pillar 1: Radio Waves—The Invisible Tool That Changed Everything

In 1895, Italian inventor Guglielmo Marconi proved that he could send radio signals across a room. By 1901, he had sent a signal across the Atlantic Ocean, from England to Canada. By the 1920s, radio had become a household staple: families gathered around their wooden radio sets every night to listen to news, music, and radio dramas.

But radio waves are more than just a way to send sound. They are a type of electromagnetic radiation, like light, but with much longer wavelengths that our eyes can’t see. They travel at the speed of light (300,000 kilometers per second, fast enough to circle the Earth 7 times in one second), and when they hit a metal object, they bounce straight back—just like a tennis ball bouncing off a wall.

Scientists in the 1930s realized this “bounce” effect could be used to detect objects you couldn’t see. If you send out a radio wave pulse, then listen for the echo, you can calculate exactly how far away the object is, how fast it’s moving, and even how big it is. The formula for this calculation is surprisingly simple: $$ \lambda = \frac{c}{f} $$ Where $ \lambda $ (lambda) is the wavelength of the radio wave, $c$ is the speed of light, and $f$ is the frequency of the wave. For example, if you use a radio wave with a frequency of 3 gigahertz (GHz, common for early radar systems), the wavelength is 10 centimeters—perfect for bouncing off small objects like planes.

For the digital edition of this book, we’ve built an interactive simulation where you can adjust the frequency of a radio wave and the size of a target to see how the bounce signal changes. [Click here to try it out](link-to-simulation). For the print edition, turn to page 12 to see a full-page annotated diagram of a 1930s BBC shortwave transmitter, the exact type of device used in the first radar tests.

By the mid-1930s, radio technology had advanced enough that scientists could send out powerful, focused radio pulses and detect the tiny echo bouncing back from a plane 100 kilometers away. The only problem was, no military leader thought this was useful. Why use invisible radio waves to find planes, when you could just look up in the sky?

Pillar 2: Atomic Physics—The Power Hidden Inside Atoms

In 1911, New Zealand physicist Ernest Rutherford proved that atoms are not solid balls, but tiny solar systems: a tiny, dense nucleus (made of protons and neutrons) sits in the center, with electrons orbiting around it like planets. For 20 years, scientists thought the nucleus was impossible to split—until 1932, when British physicist James Chadwick discovered the neutron, a tiny neutral particle that could shoot straight into the nucleus without being repelled by the positive protons.

Two years later, in 1934, Italian physicist Enrico Fermi bombarded uranium atoms with neutrons, and found that the uranium turned into slightly lighter elements. No one knew why—until 1938, when German chemists Otto Hahn and Fritz Strassmann did the same experiment and found something shocking: when they bombarded uranium with neutrons, the uranium nucleus split into two smaller nuclei, releasing a tiny amount of energy in the process. They called this process nuclear fission.

Their colleague, physicist Lise Meitner, realized what was happening: when a uranium nucleus splits, a tiny amount of its mass disappears, turned into pure energy according to Albert Einstein’s famous 1905 equation: $$ E = \Delta m c^2 $$ Where $E$ is energy, $\Delta m$ (delta m) is the missing mass, and $c$ is the speed of light. Because the speed of light is so huge, even a tiny amount of missing mass turns into an enormous amount of energy. If you could split 1 kilogram of uranium-235 (the type of uranium that fissions easily), the missing mass would be just 0.09% of the total—but the energy released would be equal to blowing up 2,700 tons of TNT explosive.

At first, no one thought this energy could be used for anything practical. The fission experiments released only a tiny amount of energy, barely enough to warm up a cup of tea. Most scientists thought using fission for a bomb was impossible. But when war came, that tiny amount of energy would become the most destructive weapon in human history.

Pillar 3: Aerospace Engineering—Breaking the Limits of Flight

In 1930, 25-year-old Royal Air Force (RAF) engineer Frank Whittle was sitting in his barracks, thinking about the limits of airplane engines. All planes at the time used piston engines, the same basic design as car engines: fuel explodes inside a cylinder, pushing a piston back and forth, which turns a propeller. But piston engines were inefficient: they lost a lot of energy to heat and friction, and they got slower and less powerful the higher the plane flew, because the air got thinner.

Whittle had a crazy idea: