Here’s what you’ll learn when you read this story:
- A San Francisco, California-based nuclear fusion startup says it’s found a way to create a stable isotope of gold through the decay of a mercury isotope.
- While this modern-day alchemy sounds impressive, the paper that establishes the new method has not yet been peer-reviewed; take its claims with a heavy dose of skepticism.
- Alchemy has a storied history of transmutations working out on paper—but less so in practice.
With Western roots in Ancient Egypt and Greece, the now-defunct scientific field of alchemy regularly consumed the thoughts of some of history’s greatest scientists. Luminaries such as Roger Bacon, Robert Boyle, and yes, even Sir Isaac Newton were convinced that “base metals” like lead could transform into “noble metals” like gold with the help of an elusive alchemical substance known as the Philosopher’s Stone. In fact, Newton wrote more than one million words on the subject, continually entranced in his quest for alchemical knowledge (all while also rewriting our very understanding of physics, gravity, and light).
Although this tireless alchemical search is often disregarded as useless pseudoscience, it helped lay the foundations of chemistry as well as the scientific method. And although alchemists’ mechanisms for transmutation—or the processes they used in attempts to change materials into other forms—were ultimately misguided, particle physics shows us that they were kinda onto something. Elements actually can transform, or rather decay, into other elements, but in ways even a great mind like Newton’s couldn’t possibly imagine at the time.
Armed with our modern understanding of the subatomic world, scientists and startups are now finding ways to achieve this millennia-long dream with fusion reactors, mind-bending machines whose entire job is to smash atoms together and create new particles.
Could this be the beginning of a new kind of gold rush?
Marathon Fusion thinks so. In a new paper published on the arXiv pre-print server—meaning the work has not yet been peer reviewed—the San Francisco-based startup lays out a plan to create a stable isotope of gold through the decay of mercury. The process relies on bombarding mercury-198 with radioactivity from energetic neutrons, transforming it into an isotope called mercury-197. This version of mercury eventually decays into gold-197.
While also producing renewable energy using heavy hydrogen isotopes tritium and deuterium, Marathon Fusion estimates that reactors could create several tons of gold per gigawatt of power. That amount far exceeds the alchemical output of CERN, the world’s leading particle accelerator lab whose ALICE experiment made an estimated 29 picograms of gold during Run 2 (2015–2018) by creating near-miss collisions with lead nuclei. Although the process created 86 billion gold nuclei, that’s still trillions of times less than would be required to make a single piece of jewelry.
So if particle accelerators aren’t the answer, maybe fusion is the way to go. But as with anything that has to do with nuclear fusion, this is another one of those “easier said than done” kinds of things. In an article for The Conversation, Queen Mary University of London physics professor Adrian Bevan, Ph.D., analyzes the truly hellish subatomic conditions Marathon Fusion’s experiment would require to even attempt to decay—or transmute as Newton might put it—mercury into gold.
“To do this, a large neutron flux (a measure of the intensity of neutron radiation) is required. This can be generated using a standard fuel mix for fusion reactors, deuterium and tritium (both of which are forms of hydrogen), to create energy in the plasma of a fusion reactor,” Bevan writes. “Neutrons penetrate material easily and scatter off the nuclei (cores) in atoms, slowing down as they do so. Neutrons with energies above 6 million electron volts are required to transform mercury-198 into gold.”
But the big, toroidal-shaped elephant in the room is that scientists are far from creating a viable commercial fusion reactor. The world’s leading tokamak effort is the International Thermonuclear Experimental Reactor, or ITER, and it won’t begin operations for another decade at least. That’s due, in part, to continued research into materials that can withstand the intense temperatures (around 100 million degrees Celsius) of a fusion reactor as well as investigating ways to control the super-hot plasma long enough to induce fusion, a task some scientists think artificial intelligence could help with.
Instead of waiting around for years to test its theory, Marathon Fusion relied on what’s known as a “digital twin,” a hyper-realistic computer model that simulates the physics and radioactivity of a nuclear fusion reactor.
This hypothetical reactor’s alchemical byproduct wouldn’t be like the old-fashioned gold in the ground that’s obsessed humans throughout recorded history. Although the half-life of mercury-197 is only 64 hours, the resulting gold isotope would be radioactive, meaning it’d need to be stowed away for an estimated 17.7 years before it could be handled safely. Despite these limitations, U.S. Department of Energy plasma physicist Ahmed Diallo, Ph.D., speaking to the Financial Times, says these initial simulation-based results are promising.
“The key insight here is that you can use this set of fast neutron reactions to make really large quantities of gold while satisfying the fuel cycle requirements of the system,” he says. “On paper it looks great and everyone so far that I talk to remains intrigued and excited.”
But for centuries, humanity’s alchemical dreams have remained forever confined to “paper,” a written realm of endless ideas never realized. Still, with the dawn of fusion energy on the horizon, the future just might be a golden one.
Darren lives in Portland, has a cat, and writes/edits about sci-fi and how our world works. You can find his previous stuff at Gizmodo and Paste if you look hard enough.