Helium

Based on Wikipedia: Helium

The Element That Escaped

Here's something unsettling: helium, the gas we casually release into the atmosphere every time a party balloon deflates, is escaping Earth forever. Once it floats up into the sky, it's light enough to drift past our atmosphere and vanish into the vacuum of space. We cannot get it back. And we're running out.

This might seem like a trivial concern. Helium is just for balloons, right? Squeaky voices at birthday parties?

Not quite. Helium is what makes MRI machines work. It cools the superconducting magnets inside to temperatures colder than outer space. Without helium, hospitals lose one of their most important diagnostic tools. Helium is also essential for manufacturing the silicon wafers that power every smartphone and computer. It's used in arc welding, rocket fuel production, and cutting-edge physics research. The squeaky voice trick is perhaps its least important application.

Yet we treat this irreplaceable element like it's disposable.

Discovered in the Sun Before Earth

Helium has one of the strangest discovery stories in science. We found it on the Sun twenty-seven years before anyone found it on Earth.

On August 18, 1868, during a total solar eclipse in Guntur, India, French astronomer Jules Janssen pointed his spectroscope at the Sun's chromosphere. A spectroscope splits light into its component wavelengths, like a prism creating a rainbow. Each chemical element produces a unique pattern of bright or dark lines at specific wavelengths, essentially a fingerprint that identifies what's present.

Janssen saw a bright yellow line at 587.49 nanometers. At first, everyone assumed it was sodium, which produces similar yellow lines. But English astronomer Norman Lockyer, observing from Britain two months later, realized this line didn't quite match sodium. It was something else. Something unknown.

Lockyer did something audacious. He concluded that this yellow line came from an element that existed on the Sun but had never been found on Earth. He named it after the Greek word for the Sun: helios. Hence, helium.

This was a remarkable leap of reasoning. In 1868, the idea that you could discover a new element by looking at starlight seemed almost absurd. Many scientists were skeptical. English chemist Edward Frankland doubted the new element existed at all. But Lockyer was right.

There's an amusing footnote to the naming. The suffix "-ium" is conventionally reserved for metallic elements: sodium, potassium, uranium. Helium is a gas, not a metal. Lockyer, being an astronomer rather than a chemist, apparently didn't know this convention. By the time anyone thought to object, the name had stuck.

Finding It on Earth

For nearly three decades, helium remained a solar curiosity. Then, in 1881, Italian physicist Luigi Palmieri detected the same spectral signature in gases escaping from Mount Vesuvius. Helium existed on Earth after all, though volcanic vents weren't exactly a practical source.

The breakthrough came on March 26, 1895. Scottish chemist William Ramsay was actually looking for argon, another noble gas, when he decided to treat a mineral called cleveite with acid. Cleveite is a variety of uraninite, a uranium-bearing ore that often contains rare-earth elements. When Ramsay dissolved it in sulfuric acid, a gas bubbled off.

After separating out the nitrogen and oxygen, Ramsay noticed a bright yellow spectral line. The same line Lockyer had seen in sunlight decades earlier. Ramsay sent his samples to Lockyer for confirmation. The Sun's element had finally been captured on Earth.

Here's where the story gets interesting. An American geochemist named William Hillebrand had actually isolated helium years before Ramsay, while testing uraninite samples. He noticed unusual spectral lines but assumed they came from nitrogen. He missed his chance at one of the great discoveries in chemistry. His gracious congratulatory letter to Ramsay is a touching document in the history of science, a reminder of how close we can come to breakthroughs without recognizing them.

The Second Most Abundant Element in the Universe

Despite being rare on Earth, helium is spectacularly common elsewhere. It's the second most abundant element in the observable universe, after hydrogen. About 24 percent of all the ordinary matter that exists is helium.

Most of this helium is ancient. It formed during the Big Bang, in the first few minutes after the universe began. At that time, conditions were hot and dense enough for nuclear fusion to occur. Hydrogen nuclei smashed together to form helium-4, which consists of two protons and two neutrons bound tightly together.

Helium-4 is remarkably stable. Its nucleus has what physicists call high binding energy per nucleon, meaning the protons and neutrons are held together very tightly. This stability explains why helium is both a product of nuclear fusion in stars and a product of radioactive decay on Earth. When heavy elements like uranium and thorium decay, they emit alpha particles, and an alpha particle is simply a helium-4 nucleus.

Stars continue making new helium constantly. Our Sun, like all stars in the main sequence of their lives, fuses hydrogen into helium in its core. This is the reaction that produces sunlight and heat. Every second, the Sun converts about 600 million tons of hydrogen into 596 million tons of helium. The missing four million tons become energy, radiating outward as light.

Where Earth's Helium Comes From

Earth's atmosphere contains only about 5.2 parts per million of helium. That's vanishingly small. So where does commercial helium come from?

The answer lies deep underground. For billions of years, radioactive elements in Earth's crust have been slowly decaying, emitting alpha particles. These helium nuclei pick up electrons from surrounding atoms and become helium gas. Most of this gas seeps upward through porous rock and eventually escapes into the atmosphere, then into space.

But sometimes, geological formations trap the gas. Natural gas reservoirs, sealed by impermeable rock layers, can accumulate significant concentrations of helium over millions of years. Some deposits contain as much as 7 percent helium by volume.

In 1903, an oil drilling operation in Dexter, Kansas, struck a gas geyser. When workers tried to ignite it, nothing happened. The gas wouldn't burn. This was puzzling, since natural gas is mostly methane, which is highly flammable.

Kansas state geologist Erasmus Haworth collected samples and brought them to the University of Kansas. With chemists Hamilton Cady and David McFarland, he analyzed the composition: 72 percent nitrogen, 15 percent methane, 1 percent hydrogen, and 12 percent of something they couldn't identify. Further testing revealed that 1.84 percent was helium.

This discovery revealed that the American Great Plains sat atop enormous helium reserves. The United States would dominate helium production for the next century.

Lighter Than Air, but Not Like Hydrogen

Helium's most obvious property is its lightness. With an atomic mass of just four (compared to nitrogen's 28 and oxygen's 32), helium provides significant lifting force. A helium-filled balloon rises because the gas inside is less dense than the surrounding air.

But helium wasn't always the preferred lifting gas. Hydrogen, with an atomic mass of just two, provides even more lift. Early aviation pioneers used hydrogen extensively. The problem, as the Hindenburg disaster demonstrated in 1937, is that hydrogen is extraordinarily flammable. Mix it with air, add a spark, and you get an explosion.

Helium is completely inert. It doesn't burn. It doesn't react with anything under normal conditions. This makes it far safer for airships, even though it provides about eight percent less lift than hydrogen.

The United States recognized this advantage early. During World War I, the Navy sponsored experimental helium plants to supply non-flammable gas for barrage balloons. By 1921, the Navy's C-7 blimp became the world's first helium-filled airship, flying from Hampton Roads, Virginia, to Washington, D.C.

The Helium Act of 1925 banned exports of the gas, which the United States then monopolized. This had fateful consequences. German Zeppelins, unable to obtain American helium, had to use hydrogen instead. When the Hindenburg caught fire while landing in New Jersey, the resulting inferno killed 36 people and effectively ended the era of passenger airships.

The Coldest Liquid

Helium has the lowest boiling point of any element: 4.22 Kelvin, or about minus 269 degrees Celsius. To put that in perspective, absolute zero, the coldest temperature theoretically possible, is zero Kelvin. Helium remains liquid just four degrees above that limit.

In 1908, Dutch physicist Heike Kamerlingh Onnes became the first person to liquefy helium. This was a remarkable achievement, requiring sophisticated refrigeration equipment that didn't exist until Onnes built it. He cooled helium gas to less than 5 Kelvin, and it condensed into a clear, colorless liquid.

Onnes then tried to solidify it by cooling it further. He failed. No matter how close he got to absolute zero, the helium remained liquid. This seemed to violate basic thermodynamics, since all substances should eventually freeze if cooled enough.

The explanation involves quantum mechanics. Helium atoms are so light and their quantum uncertainty so significant that even at absolute zero, they retain enough motion to prevent crystallization. Helium will only solidify under pressure. Onnes's student Willem Hendrik Keesom finally managed to freeze a small amount in 1926, but only by applying external pressure beyond normal atmospheric levels.

Superfluidity: When Physics Gets Strange

In 1938, Russian physicist Pyotr Kapitsa discovered something extraordinary. When helium-4 is cooled below 2.17 Kelvin, it transforms into a state unlike any other known substance. Its viscosity, the internal friction that makes liquids resist flow, drops to essentially zero.

This state is called superfluidity. Superfluid helium does things that seem to defy common sense. It can climb up the walls of its container and escape. It can flow through microscopic pores and cracks that would block any normal liquid. It conducts heat thousands of times more efficiently than copper.

The explanation lies in Bose-Einstein condensation. At extremely low temperatures, helium-4 atoms, which are bosons (particles with integer spin), collectively drop into the same quantum state. They stop behaving as individual particles and act as a single quantum entity. This is one of the few places where quantum mechanical effects become visible at a macroscopic scale.

Helium-3, the lighter isotope with only one neutron instead of two, is a fermion (a particle with half-integer spin). Fermions cannot occupy the same quantum state due to the Pauli exclusion principle. For decades, physicists assumed helium-3 couldn't become superfluid.

They were wrong. In 1972, American physicists Douglas Osheroff, David Lee, and Robert Richardson discovered that helium-3 does become superfluid, but only at temperatures below 0.0025 Kelvin, nearly a thousand times colder than helium-4's transition. The mechanism is different: pairs of helium-3 atoms combine to form composite bosons, similar to how electron pairs form in superconductors. All three physicists won the Nobel Prize for this discovery.

The Heart of Medical Imaging

Today, the largest single use of helium is cooling superconducting magnets, and the most important application of those magnets is medical imaging.

Magnetic Resonance Imaging, or MRI, works by placing a patient inside an extremely powerful magnetic field. This field aligns the hydrogen atoms in body tissues. Radio waves then disturb this alignment, and as the atoms realign, they emit signals that can be reconstructed into detailed images.

To generate the necessary magnetic field strength, MRI machines use superconducting electromagnets. Superconductors carry electrical current with zero resistance, allowing enormous currents and thus enormous magnetic fields. But superconductivity only occurs at extremely low temperatures. The magnets must be bathed in liquid helium to stay cold enough to function.

A typical MRI scanner contains about 1,700 liters of liquid helium. The helium slowly boils off and must be periodically replenished. If the supply is interrupted, the magnet warms up, loses superconductivity, and shuts down. Getting it running again is expensive and time-consuming.

Hospitals around the world depend on a steady helium supply. During helium shortages, some facilities have had to limit MRI appointments or shut down scanners entirely. This is a genuine public health concern, not merely an industrial inconvenience.

The Strategic Reserve

Recognizing helium's importance, the United States government established the National Helium Reserve in 1925 at Amarillo, Texas. The original purpose was military: ensuring a supply for airships in wartime. As airship technology faded, the reserve's mission evolved to support the Space Race and Cold War.

Liquid helium was essential for producing rocket fuel. Both liquid hydrogen and liquid oxygen, which power rockets, require extremely cold temperatures for storage and handling. Helium provided the necessary cooling. By 1965, American helium consumption was more than eight times the wartime peak.

The government built a 425-mile pipeline from Kansas to the Cliffside gas field near Amarillo, where partially purified helium-nitrogen mixtures could be stored underground until needed. By 1995, the reserve held a billion cubic meters of helium.

It also held $1.4 billion in debt. Congress, questioning whether the government should be in the helium business, passed the Helium Privatization Act of 1996, directing the Interior Department to sell off the reserve. This decision remains controversial. Critics argue that selling a finite, non-renewable strategic resource at below-market prices amounts to giving away a national asset.

A Global Scramble

For most of the twentieth century, the United States produced over 90 percent of the world's helium. This began changing in the 1990s. A plant in Arzew, Algeria, opened in the mid-1990s, producing enough helium to supply all of Europe. Additional plants followed in Qatar and elsewhere.

Algeria quickly became the second-largest producer. Then Qatar built the world's largest helium facility, which came online in 2013. This diversification should have eased supply concerns. Instead, it created new vulnerabilities.

The 2017 Qatar diplomatic crisis, in which Saudi Arabia and other Gulf states imposed a blockade on Qatar, severely disrupted helium shipments. Political instability in Algeria has also caused production interruptions. The global helium market has experienced alternating periods of shortage and oversupply, making prices volatile and planning difficult.

From 2002 to 2007, helium prices doubled. Some years, like 2014, saw gluts. Other years brought severe shortages. Research laboratories have had to curtail experiments. Industrial users have scrambled for alternatives where possible, though for many applications, no alternative exists.

The Depletion Question

Is helium actually running out? The answer is complicated.

Helium is undeniably finite on Earth. What escapes into the atmosphere eventually drifts into space. New helium is constantly being produced by radioactive decay deep underground, but the rate of production is far slower than current consumption.

However, "running out" depends on timescale and price. At higher prices, previously uneconomical deposits become worth extracting. New exploration has identified helium-rich gas fields that weren't known decades ago. Some studies suggest that volcanic activity releases more radiogenic helium than previously thought, potentially replenishing some underground reservoirs.

The U.S. National Helium Reserve was projected to be exhausted by 2018. It wasn't. Production continued, though at reduced levels. New plants opened in Wyoming, Qatar, and Russia, partially offsetting declines elsewhere.

Still, the fundamental economics haven't changed. Helium remains a byproduct of natural gas extraction. If natural gas demand falls due to climate policies or competition from renewables, helium production could decline as well. No one extracts natural gas solely for its helium content; it's not valuable enough to justify the infrastructure on its own.

What Makes Helium Special

Helium belongs to the noble gases, a family of elements in the rightmost column of the periodic table. This group includes neon, argon, krypton, xenon, and radon. What unites them is their electron configuration: each has a complete outer electron shell, making them extremely stable and unreactive.

Helium is the simplest noble gas, with just two protons, two neutrons (in the common isotope), and two electrons. Those two electrons completely fill helium's only electron shell. There's no room for more electrons and no tendency to lose the ones it has. Helium simply doesn't want to participate in chemistry.

This inertness has practical value beyond safety. In arc welding, helium creates a protective atmosphere that prevents the molten metal from reacting with oxygen or nitrogen. In semiconductor manufacturing, helium's purity and non-reactivity make it ideal for growing silicon crystals. In leak detection, helium's small atomic size allows it to penetrate the tiniest cracks, making it perfect for testing sealed containers and vacuum systems.

The Voice Change Explained

The squeaky helium voice is perhaps the element's most famous party trick. Inhale a little helium, speak, and your voice jumps up in pitch. Or does it?

Technically, the pitch of your voice, the fundamental frequency at which your vocal cords vibrate, doesn't change. What changes is the timbre, the characteristic quality that makes your voice sound like you.

Sound travels faster through helium than through air, about three times faster. When you speak with helium filling your vocal tract, the resonant frequencies shift upward. Your voice's higher harmonics are amplified relative to lower ones. The result sounds higher-pitched, even though the fundamental frequency remains the same.

The opposite effect occurs with sulfur hexafluoride, a gas denser than air. Sound travels more slowly through it, amplifying lower harmonics and making your voice sound deeper, almost demonic.

Neither trick is entirely safe. Helium displaces oxygen, and inhaling too much can cause asphyxiation. Deaths have occurred, usually from people inhaling directly from pressurized tanks. A few breaths from a balloon is generally harmless, but the party trick has a dark edge.

Quantum Mechanics and the Helium Atom

In physics, helium occupies a special place. The hydrogen atom, with just one proton and one electron, can be solved exactly using quantum mechanics. Every energy level, every transition, every property can be calculated precisely from first principles.

Helium is the next simplest atom, but adding just one more electron makes exact solutions impossible. The three-body problem, two electrons interacting with a nucleus and with each other, has no closed-form solution. Every calculation must be approximate.

This makes helium a crucial test case. Physicists compare increasingly sophisticated approximations against precise experimental measurements. The agreement between theory and experiment in helium spectroscopy represents one of quantum mechanics' greatest triumphs.

In 1913, Niels Bohr used helium to support his new model of the atom. A series of mysterious spectral lines, first observed in the star Zeta Puppis, had been attributed to a strange form of hydrogen with half-integer quantum levels. Bohr's model predicted that such half-integer transitions couldn't exist. He argued that the lines must come from ionized helium instead, helium atoms that had lost one electron.

Bohr was right. By 1915, spectroscopists had confirmed that these lines belonged to helium, not hydrogen. This validation helped establish quantum theory during its revolutionary early years.

Looking Forward

Helium's story encapsulates a tension that runs through modern industrial society. We depend on finite resources extracted from the Earth. Some, like oil, can theoretically be replaced by alternatives. Others, like helium, cannot.

No chemical process can create helium in useful quantities. Nuclear reactions can produce it, but not economically. Once it's gone from Earth, it's gone.

The good news is that conservation and recycling efforts are improving. MRI facilities are increasingly recapturing the helium that boils off from their machines rather than venting it. Research laboratories are investing in closed-loop cooling systems. Higher prices, painful as they are, encourage efficiency.

New exploration continues. Helium deposits have been found in Tanzania that may rival existing reserves. Better geological understanding helps identify promising sites for drilling.

But the fundamental trajectory is clear. Helium is being depleted faster than natural processes replenish it. Someday, perhaps decades or centuries from now, this lightest of noble gases will become scarce enough to transform the technologies that depend on it.

Until then, every helium-filled balloon drifting into the sky carries a piece of an irreplaceable resource off the planet forever. It's worth asking whether squeaky voices at birthday parties are really the best use we can find for an element first discovered on the Sun.