For thousands of years, alchemists attempted to unlock the secrets of the universe. One aim was to turn lead into gold. This process was called transmutation, and with it, alchemists believed they could transform the world.
Of course, they never succeeded. Eventually, alchemy gave way to modern science: chemistry, astronomy, physics. But the appeal of transmutation isn’t gone, leaving some scientists to wonder—is it possible to make gold out of lead?
The answer is: well, sort of. Let’s start with some chemistry basics that the old alchemists didn’t know. First, every atom has protons and neutrons in its nucleus, which is orbited by electrons. What makes an element unique is its number of protons. For instance, each atom of gold has exactly 79 protons.
Second, changing the number of protons in a nucleus can be extremely difficult. To add protons naturally, you need nuclear fusion, which usually only happens inside stars. To remove protons, you need radioactive decay, where an unstable atom can stabilize by, say, converting a proton to a neutron.An advanced laboratory can tweak these processes. The element mercury has 80 protons—one more proton than gold. In the 1940s, scientists accelerated a neutron beam to near the speed of light. The beam hit some mercury and sheered off the mercury atoms’ eightieth protons. The scientists had created gold! But the few atoms they managed to create were radioactive, and quickly decayed into other elements. Plus, accelerating a neutron beam is very expensive. And while researchers have run this experiment again, the result is the same: transmutation is possible. But the results would probably disappoint an alchemist.