The hydrogen atom has a fascinating story in human “firsts.” Daniel Kleppner, Lester Wolfe Professor Emeritus of Physics at MIT, articulated the influence of hydrogen on the advancement of science when he said, “In its special role as the simplest of all atoms, hydrogen has starred in some great episodes in the history of science.” Hydrogen is so simple, so elegant in its internal composition, that it was initially thought to be the basic building block of matter.
Although it is the most abundant element in the universe and is present in every molecule of water here on Earth, hydrogen was invisible to us until the 16th century. That is when scientists first observed a mysterious substance they referred to as “flammable air,” which paradoxically, produced water when combusted. The surprises from “the mother of all atoms” were far from over. This intriguing “new” element proved to be lighter than air, enabling humans to fly well before the advent of the airplane. Hydrogen opened the door to the discovery and understanding of quantum mechanics. As an energy source, hydrogen powers rockets, the Hubble Space Telescope, and holds the promise to become a mainstream clean fuel for all types of applications.
Eagle Nebula’s Pillars of Creation. As seen in visible light, capturing the multi-colored glow of hydrogen gas clouds, dark cosmic dust, and newborn stars. Image captured by the Hubble Space Telescope, which is powered by hydrogen when the Earth blocks the sun. Image by ESA/Hubble under Creative Commons Licensing.
The importance of the hydrogen atom to science, and our understanding of the natural world, cannot be overestimated. Here are the ten “firsts” in the fascinating history of hydrogen’s crucial role in science, technology, and society—and the scientists whose work with this all-important element enabled progress.
1. 1671: First-time hydrogen gas is produced in a lab
Before the 16th century, nobody had ever “seen” hydrogen. As abundant as it is, in its pure molecular form, it is so light and so prone to mixing with other elements, that it isn’t commonly found on Earth. The first scientist to “see” it was Swiss alchemist Paracelsus in 1536 who unknowingly observed hydrogen when he noted a gaseous byproduct arising from acids attacking metals. It was 135 years later, in 1671, that British scientist Robert Boyle, who’s regarded as the first modern chemist and pioneer of the modern experimental scientific method, replicated this experiment with iron filings and acids. This mix resulted in the production of highly reactive pure hydrogen and is widely recognized as the first-ever hydrogen gas produced in a lab using the scientific method.
2. 1766: Hydrogen recognized as a discrete substance for the first time
It took nearly one hundred years to realize that Boyle’s gas was more than a by-product of a reaction. In 1766, Henry Cavendish was the first to isolate and characterize hydrogen as a discrete substance, naming the gas from the metal-acid reaction “flammable air.” He speculated that “flammable air” was, in fact, identical to the hypothetical substance called “phlogiston” (a 17th-century theory that tried to explain oxidation by postulating that a fire-like element called phlogiston is contained within combustible bodies and released during combustion). Then in 1781, Cavendish discovered that when his “flammable air” burned, it combined with oxygen to produce water. After months of speculating, his work on this novel gas led him to realize that he had, in fact, discovered an element, not just a substance. Two years later, French chemist Antoine Lavoisier gave the element the name hydrogen (from the Greek ὑδρο- hydro meaning “water” and -γενής genes meaning “creator”).
3. 1783: Hydrogen powers the first human aircraft
A hundred years before the invention of the airplane, humans took flight using hydrogen. It did not take much time after realizing that this new “gas” was lighter than air to ideate a way to lift humans into the sky. The first hydrogen-filled balloon was invented by Jacques Charles in 1783. A few decades later, hydrogen became the first reliable form of air travel following the 1852 invention of the first hydrogen-lifted airship by Henri Giffard. This invention inspired German Count Ferdinand von Zeppelin to devise rigid airships lifted by hydrogen that later were called Zeppelins, the first of which made its maiden flight in 1900. Regularly scheduled flights started in 1910 and by 1914, 35,000 passengers had taken to the sky in these airships. Hydrogen also powered the first non-stop transatlantic crossing by air, which was made by the British airship R34 in 1919.
4. 1806: Hydrogen is used to power engines for the first time
The internal combustion engine was a new technology in the 1800s, and many scientists were experimenting with different ways to power it. Hydrogen’s energetic potential gave French scientist and politician François Isaac de Rivaz the idea to build the first engine powered by hydrogen. This engine came to be known as the de Rivaz engine, an internal combustion engine powered by a mixture of hydrogen and oxygen. This engine had an electric ignition system used to start the reaction between the two elements. Just a year later, Rivaz obtained a French patent for his invention, which was published in 1807. The hydrogen-powered internal combustion engine preceded the gasoline-powered engine by 50 years.
5. 1913: Hydrogen is used to establish the atomic model of elements
In 1913, Danish physicist Niels Bohr discovered that the hydrogen atom is made up of a positively charged nucleus of very small dimensions and an even smaller electron closely orbiting around it. His work with hydrogen led him to perfect the first theoretical model of the atom by introducing the relationship between the radius of the electron orbits and the energy contained in them. He published his findings in a set of three papers, known as the “Bohr Trilogy,” which became seminal for understanding the structure of the atom. Importantly, his measurements with hydrogen allowed him to include in his atomic model the quantum effect to explain how electrons “jumped” orbits and changed their energy state.
6. 1925: The quantum effect is proven by experimenting with hydrogen
In 1925 and 1926, the work of three physicists on the hydrogen atom enabled science to develop the model and the explanation for quantum mechanics. First, Werner Heisenberg laid the groundwork to establish the theory of quantum mechanics by working on the wave-particle duality of photons and electrons. Specifically, he focused on the frequencies and intensities of spectral transitions in the hydrogen atom. The model was completed when Paul Dirac introduced Einstein’s Theory of Relativity to explain the effect that the elliptical orbits of electrons had on the energy spectra of hydrogen. At the same time, Wolfgang Pauli developed the mathematics around it all. After the work of these three physicists, Quantum Mechanics became widely regarded as one of the most solid physical theories to explain what happens at the subatomic level. Quantum mechanics has not only consistently been proven through experimentation, but it is also the basis for many technologies we depend on in our daily lives.
7. 1938: Work on hydrogen results in the Magnetic Resonance Method—the precursor to MRI
In 1938, Isidor Rabi, working at Columbia University, created an experiment to configure the magnetic field for deflecting particles in a molecular beam. The Magnetic Resonance Method he invented enabled scientists to measure the magnetic moment of protons and deuterons; these measurements gave us the first accurate measures of the size of the nucleus of atoms and the ways in which it behaves. A few years later, just after WWII, his method was adopted as a noninvasive medical diagnostic tool to “see” inside the human body—which led to the MRI machines that are widely used throughout the world today.
8. 1960: The atomic clock is invented
It was Isidor Rabi who, once again, first suggested the possibility of atomic clocks in 1945. Based on this idea, Norman Ramsey and his student Daniel Kleppner (who I quoted in my opening), invented the high-precision hydrogen maser clock in 1960, which became the first successful atomic clock stable to one second in 300 million years. Applications of their invention came immediately. The first applications were implemented by NASA, who used sets of atomic clocks and receivers to triangulate the actual positions of space probes (by precisely measuring the time the radiations from these probes arrived). This technology evolved out of academia and government to become the basis of modern Global Positioning Systems (GPS), which guides all satellites and enables every single location-based app on our mobile phones today.
9. 1977: First hydrogen battery enables space exploration
Although hydrogen has been powering rockets since the U.S. and the USSR launched the space age in the 1950s, it is the subsequent invention of the hydrogen battery that has enabled us to explore Mars and run the International Space Station (ISS). These batteries are known as nickel hydrogen batteries and were used for the first time in 1977 aboard the U.S. Navy’s Navigation Technology Satellite-2 (NTS-2). Today, the ISS and several NASA planetary probes, such as Mars Odyssey and the Mars Global Surveyor, are equipped with nickel-hydrogen batteries. In the dark part of its orbit (when the Earth blocks the sun), the Hubble Space Telescope is also powered by nickel-hydrogen batteries. The Hubble batteries lasted for more than 19-years after launch before being replaced by new ones.
10. 1996: Antihydrogen becomes the first antimatter particle ever produced in a lab
I find it quite fitting to close this list of ten hydrogen “firsts” with something that today still sounds like science fiction. Since its scientific discovery, hydrogen has defied prevailing common understanding—such as producing water when burned, or being lighter than air. So, the last “first” on our list is related to antihydrogen, which is the antimatter counterpart to hydrogen. Antimatter is one of quantum mechanics implications. The first particle of it, a positron, was observed by Carl Anderson at the California Institute of Technology in 1932. In would take more than 60 years before scientists could actually produce an antimatter particle in the lab; this feat was enabled by hydrogen. In 1996, antihydrogen was produced at CERN and to this day, it is the only type of antimatter atom ever to have been produced.
Humanity is not done with hydrogen “firsts” that progress science and technology to the betterment of society. The universe’s most abundant and energetic element has been the source of inspiration for many of the most important discoveries of the last 500 years. The study of hydrogen, in its unique position as the simplest of all atoms, has helped physicists uncover the workings of the subatomic world. Hydrogen enabled them to understand basic concepts such as the building blocks of matter, energy, and the nature of light. Hydrogen is so fundamental and basic to our understanding of the natural world that it will continue to lead the advancement of science and provide benefits to society as this new knowledge makes its way into practical applications.
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