So, it finally happened. A San Francisco-based startup called Marathon Fusion just claimed they’ve basically figured out alchemy. Yes, that alchemy. The kind where you turn lead—or in this case, mercury—into actual, physical gold.
It sounds like total clickbait. If you heard this in a bar, you’d probably roll your eyes and order another drink. But the people behind this aren't exactly wearing wizard hats. We're talking about Adam Rutkowski, a former SpaceX engineer, and Kyle Schiller, a science policy alum from Schmidt Futures. They recently dropped a paper that has the physics world buzzing, and honestly, the math actually checks out.
The core of the claim is that fusion energy start-up claims to have cracked alchemy by using the "waste" neutrons from a nuclear fusion reactor to transmute elements. It's not magic; it’s just very high-energy nuclear billiards.
The Science of Modern-Day Alchemy
To understand why this isn't just a fever dream, you have to look at how a standard fusion reactor works. Most of these machines, like the massive ITER project or the ones being built by Commonwealth Fusion Systems, want to fuse deuterium and tritium. When these hydrogen isotopes smash together, they create helium and a very, very fast neutron.
Usually, those neutrons are just a headache. They smash into the reactor walls, making things radioactive and brittle. Engineers try to catch them in "breeding blankets" to make more fuel. Marathon Fusion’s "aha!" moment was realizing those neutrons could do a second job.
By shoving mercury-198 into that breeding blanket, the high-energy neutrons can knock a neutron out of the mercury atom. This turns it into mercury-197. Now, mercury-197 is a bit of a mess—it’s unstable. But over about 64 hours, it naturally decays. And what does it decay into? Gold-197.
That is the only stable version of gold that exists in nature. It's the real deal.
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Why Mercury?
- Atomic Proximity: Mercury has 80 protons. Gold has 79. You just need to convince the nucleus to change its identity slightly.
- Abundance: Mercury isn't exactly rare, though it is toxic.
- The Yield: Marathon’s modeling suggests a single 1-gigawatt fusion plant could spit out 5,000 kilograms of gold a year.
At current market prices, that is roughly $350 million to $550 million in pure "side-hustle" revenue for a power plant. Basically, the gold pays for the electricity, or vice versa. It potentially doubles the economic value of the entire facility.
Is This Too Good to Be True?
Kinda. There is always a catch when you’re playing with the periodic table.
First, the gold isn't exactly "jewelry-ready" the second it comes out of the machine. Because natural mercury is a mix of different isotopes, the neutrons will hit other things too. This creates a cocktail of gold isotopes, some of which are "hot." You can’t exactly wear a radioactive wedding ring.
Rutkowski and his team admit that this gold might need to sit in a lead-lined vault for 14 to 18 years before it’s cool enough to touch. That’s a long time to wait for your paycheck.
Then there’s the "fusion" part of the fusion energy start-up claims to have cracked alchemy. We still don't have a commercial fusion reactor that actually works. We’ve seen "ignition" at the National Ignition Facility, sure, but that’s a multi-billion dollar laser hitting a tiny pellet once or twice a day. To make 5,000kg of gold, you need a reactor running 24/7, year-round. We are years—maybe decades—away from that.
The Economic Paradox
If every fusion plant starts printing gold, what happens to the price of gold?
Honestly, it probably crashes.
The annual global production of mined gold is roughly 3,600 tonnes. If just ten of these fusion plants come online, they’d increase the world’s gold supply by 50 tonnes a year. That’s not a total market collapse, but it’s enough to make investors nervous.
Why This Matters for the Energy Crisis
The real reason Marathon Fusion is talking about gold isn't because they want to be the next Fort Knox. It’s because fusion energy is insanely expensive to develop.
Investors are pouring billions into startups like Helion, TAE Technologies, and Zap Energy, but the path to profitability is a long, dark tunnel. By "cracking alchemy," Marathon is offering a way to make the books balance much sooner.
If a plant can sell $500 million of electricity and $500 million of gold, the "Levelized Cost of Energy" (LCOE) plummets. It makes fusion competitive with cheap natural gas or solar. It turns a "maybe-in-our-lifetime" technology into a "we-need-to-build-this-now" business case.
Dr. Per Peterson, a heavy hitter in nuclear engineering at UC Berkeley, has noted that this approach fundamentally changes how we think about fusion. It’s no longer just a power plant; it’s a transmutation factory.
What Most People Get Wrong
People hear "alchemy" and think of Isaac Newton's secret notebooks or some guy in a basement trying to dissolve lead in acid. That’s not this. This is nuclear transmutation, a process we've actually known about since the 1940s.
In 1941, physicists at Harvard and MIT actually did turn mercury into gold using a cyclotron. The problem was it cost way more in electricity than the gold was worth. It was a neat trick, but a terrible business.
What’s different now is the neutron flux. A fusion reactor is a neutron firehose. It provides the "free" subatomic particles you need to do the transformation on an industrial scale.
Real-World Limitations
- Isotope Separation: To avoid the 18-year "cooling off" period, you’d need to use pure mercury-198. Separating isotopes is expensive and difficult (ask anyone who’s ever tried to enrich uranium).
- Engineering Heat: Handling molten mercury or mercury vapor inside a fusion environment is a chemical engineering nightmare.
- Regulatory Red Tape: The NRC (Nuclear Regulatory Commission) isn't exactly known for moving fast. A "gold-printing nuclear reactor" would likely trigger every regulatory alarm bell in existence.
The Actionable Insight: What Should You Do?
If you're an investor or just a tech nerd, don't go selling your gold bars just yet. But keep a very close eye on the "transmutation" sub-sector of the fusion industry.
The most important thing to watch is the peer review of Marathon Fusion's paper. If the broader scientific community agrees that the neutron economy—the balance of how many neutrons you use vs. how many you need to keep the fire going—holds up, then the "alchemy" claim moves from science fiction to a legitimate financial model.
Next Steps for the Curious:
- Monitor the Fusion Industry Association (FIA) reports. They track which startups are hitting their milestones.
- Research "Aneutronic Fusion." Companies like TAE and Helion are trying to avoid neutrons altogether. If they succeed, Marathon's gold-making method won't work on their machines.
- Look into Medical Isotopes. Even if gold fails, the same technology can be used to create Molybdenum-99, which is used in millions of cancer scans but is currently in short supply.
The fusion energy start-up claims to have cracked alchemy might be the ultimate marketing play, but it’s grounded in the kind of physics that once seemed impossible and now just seems like a very difficult engineering problem. Whether we get gold or not, the pursuit of it might just give us the clean energy we actually need.