Lead becomes gold | Discover the magazine
Practitioners of alchemy, the medieval and more spiritual predecessor of chemistry, once had one saying: “It is more difficult to destroy gold than to mine it.” Gold – pure gold – is remarkably resistant to fire, acid and rust. Aside from shooting it in the sun or throwing it into a volcano, it is actually your only chance to annihilate the element in a nuclear reactor for a while.
So it’s no wonder gold has so caught the human imagination. Alchemists from China, India, and Europe have been obsessed with converting base metals (especially lead) into gold for centuries. They were looking for a mythical substance, the so-called “Philosopher’s Stone”, to accomplish this task, to no avail. Their techniques, along with many of their assumptions about the world, have long been relegated to the realm of pseudoscience, but the alchemists may have been on to something.
Indeed, they were right that lead could be turned into gold – even if they were completely mistaken about how to do it. Today modern science routinely takes us well beyond the wildest dreams of the alchemists.
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One of the most famous stories about nuclear transmutation dates back to the 1970s when nuclear chemist and Nobel Prize winner Glenn Seaborg attended the Lawrence Berkeley National Laboratory together with his colleague Walt Loveland and the then PhD student Dave Morrissey. Scientists used a superheavy ion linear accelerator to bombard atoms with ions as heavy as uranium at relativistic speeds. “Among those we bombed was lead-208,” says Loveland.
The acceleration of the ions close to the speed of light enabled them to study nuclear reaction mechanisms. “We would measure the products and mostly focus on the yields,” says Loveland. Some of that income was gold. “It was all relatively routine. Then Seaborg said, ‘Hey, look at this – you’re converting lead into gold and doing the alchemists’ dream reaction.’ “Miami.
“It caused a sensation when I did it at the. have reported […] meet, but it’s not particularly difficult or unique, ”says Morrisey. “You can use different nuclear reactions to convert practically any element into another nearby element.”
Meanwhile Seaborg did his own “alchemy”; he was busy turning an everyday nuclear research event into a spectacular story. “Seaborg has been a great manipulator of the press,” says Loveland. “He got a lot of publicity from this idea of the alchemist’s dream.” Many reporters, as enthusiastic as the alchemists once were about the prospect of people making gold and enriching themselves, got in touch.
The story might have picked up speed, but it encountered some political headwinds. The experiment had caught the attention of Wisconsin Senator William Proxmire, who loved to impale officials for wasting taxpayers’ money. It was not even remotely cost-effective to mine gold this way back then. “… It was about $ 5,000 an hour to run the accelerator,” says Loveland, so they dropped it.
This was nowhere near the first time humans have made gold – either on purpose or by accident. Berkeley Lab’s Matthew Nerzig explains that for decades before Seaborg’s experiment, radioactive gold isotopes were made in particle accelerators. 1937, the physicist and Nobel Prize winner Ed McMillan made the first artificial gold isotopes with deuteron beams in one of the first cyclotrons, an early model of particle accelerators. Deuterons are stable hydrogen isotopes, consisting of a proton and a neutron; they are often used as ammunition in particle accelerators.
The business of nuclear research, of course, is often the process of transformation and sometimes creation. The heaviest 26 elements in the periodic table, for example, have only been observed in the laboratory until now – right after some clever people created them. Efforts are currently being made to create items 199 and 120, says Loveland. And in order to study the most exotic features of the universe, such as the quark-gluon plasma, which may form the heart of neutron stars, scientists must first create them in particle accelerators.
In the heyday of alchemy there was both hope and concern about its practical possibilities. After all, a nation that could turn ordinary metals into gold could very easily get very rich. Isaac Newton, perhaps the most famous alchemist of all time, was reportedly very concerned about the public knowledge of alchemy and never wrote about it explicitly in his published writings.
But while nuclear science has practical applications in both nuclear weapon development and nuclear medicine, Loveland says, the vast majority of work today is focused solely on better understanding the mechanisms of nuclear responses. (Newton and the rest of us can rely on this knowledge.)
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