Skip to main content

Gold comes from stars

By Meg Urry, Special to CNN
updated 3:13 PM EDT, Sat July 20, 2013
STORY HIGHLIGHTS
  • New studies suggest gold could be created in the collision of two neutron stars
  • Meg Urry: Most elements were made by nuclear fusion inside a star, but not precious metals
  • She says the next time you wear gold, remember that it came from deep in space

Editor's note: Meg Urry is the Israel Munson professor of physics and astronomy at Yale University and director of the Yale Center for Astronomy and Astrophysics.

(CNN) -- Ancient Egyptians buried their dead with it. In 1848, Americans flocked to California to find it. If you're over 40, your dentist may have filled your mouth with it. And Germany wants their 674 tons of it back from the Federal Reserve Bank of New York.

Yes, we're talking gold. Atomic number 79 in the Periodic Table of the Elements, lustrous metal used for jewelry, valuable substance for electronic circuitry.

Where does it come from?

Meg Urry
Meg Urry

New results from studies of a gamma-ray burst -- an extremely energetic, fast explosion, typically from the distant universe -- suggest gold could be created in the collision of two neutron stars, which are kind of like two giant atomic nuclei.

CNN: All the world's gold came from collisions of dead stars

Let's pause for a chemistry refresher. An atom is made of a tightly bound nucleus of protons (positively charged) and neutrons (uncharged), orbited by electrons (negatively charged) -- a bit like planets orbiting the Sun, except instead of gravity, the electromagnetic force keeps the electrons orbiting the nucleus. (Also the laws of quantum mechanics are important -- but that's another story.)

The identity of an atom is determined primarily by the number of protons it has. Gold has 79 protons, hence, its atomic number. That's one more than platinum, two more than iridium, three less than lead.

Scientists think most of the elements lighter than iron (atomic number 26) were forged in the dense cores of stars much heavier than our Sun. At the end of their lifetimes, these stars explode violently in a supernova, dispersing the newly created elements across interstellar space.

In fact, most of the elements that make up your body and everything around you -- other than hydrogen and helium, the two lightest elements -- were made by nuclear fusion inside a star somewhere, long before the Earth formed. Physicists and astronomers figured this out in the last century.

However, the heavier elements, including precious metals like gold, silver and platinum, or cell phone ingredients like copper, palladium, zinc, beryllium, and, yes, gold, were not made this way.

Instead, these elements were forged in stellar explosions, as extra neutrons and protons were propelled into atomic nuclei.

Like modern-day alchemists, nuclear physicists can in principle turn lead into gold using particle accelerators and nuclear reactors (although it's easier to turn mercury into gold).

But don't get your hopes up. Producing a small amount of gold costs enormously more than it's worth so this isn't any way to get rich.

Obviously, nature makes gold, or miners wouldn't find it in rocks and streams. But nature doesn't manufacture it easily. Indeed, a supernova is more likely to turn gold into lead than the other way around.

So now Edo Berger of Harvard University thinks he might know where all this gold came from. Scientists have suspected for a decade that some powerful gamma-ray bursts could result from the collisions of two neutron stars. Because neutron stars are incredibly dense collections of neutrons -- basically, like a bizarre, gigantic, atomic nucleus -- smashing them together is bound to create atoms containing many neutrons and protons, including good old gold.

Berger thinks the faint infrared light seen by NASA's Hubble Space Telescope from a gamma-ray burst detected last month by NASA's Swift gamma-ray space telescope might come from radioactive decay of heavy elements created in the collision. During the collisions, neutrons captured by lighter nuclei should create such radioactive elements, which can then decay into other elements, producing the infrared light he saw.

In addition to lead, thorium, and uranium, one of the (minor) by-products should be gold.

Could this be where your jewelry came from, the violent collision of two exotic neutron stars?

"To paraphrase Carl Sagan," says Berger, "We are all star stuff, and our jewelry is colliding-star stuff."

So next time you put on that necklace, admire a gilded painting, or talk on your cell phone, pause to remember that it came from rare collisions of neutron stars in deep space. And figure that the next gamma-ray burst we discover might just have made as much gold as there is on Earth.

Follow us on Twitter @CNNOpinion.

Join us on Facebook/CNNOpinion.

The opinions expressed in this commentary are solely those of Meg Urry.

ADVERTISEMENT
Part of complete coverage on
updated 3:30 AM EDT, Sun September 21, 2014
John Sutter boarded a leaky oyster boat in Connecticut with a captain who can't swim as he set off to get world leaders to act on climate change
updated 7:22 PM EDT, Fri September 19, 2014
Is ballet dying? CNN spoke with Isabella Boylston, a principal dancer at the American Ballet Theatre, about the future of the art form.
updated 5:47 PM EDT, Fri September 19, 2014
Sally Kohn says it's time we take climate change as seriously as we do warfare in the Middle East
updated 9:02 AM EDT, Fri September 19, 2014
Dean Obeidallah says an Oklahoma state representative's hateful remarks were rightfully condemned by religious leaders..
updated 3:22 PM EDT, Fri September 19, 2014
No matter how much planning has gone into U.S. military plans to counter the Islamic State in Iraq and Syria, the Arab public isn't convinced that anything will change, says Geneive Abdo
updated 11:44 AM EDT, Fri September 19, 2014
President Obama's strategy for destroying ISIS seems to depend on a volley of air strikes. That won't be enough, says Haider Mullick.
updated 9:03 AM EDT, Fri September 19, 2014
Paul Begala says Hillary Clinton has plenty of good reasons not to jump into the 2016 race now
updated 11:01 AM EDT, Fri September 19, 2014
Scotland decided to trust its 16-year-olds to vote in the biggest question in its history. Americans, in contrast, don't even trust theirs to help pick the county sheriff. Who's right?
updated 9:57 PM EDT, Thu September 18, 2014
Ruben Navarrette says spanking is an acceptable form of disciplining a child, as long as you follow the rules.
updated 11:47 AM EDT, Fri September 19, 2014
Frida Ghitis says the foiled Australian plot shows ISIS is working diligently to taunt the U.S. and its allies.
updated 3:58 PM EDT, Fri September 19, 2014
Young U.S. voters by and large just do not see the midterm elections offering legitimate choices because, in their eyes, Congress has proven to be largely ineffectual, and worse uncaring, argues John Della Volpe
updated 9:58 PM EDT, Thu September 18, 2014
Steven Holmes says spanking, a practice that is ingrained in our culture, accomplishes nothing positive and causes harm.
updated 2:31 PM EDT, Thu September 18, 2014
Sally Kohn says America tried "Cowboy Adventurism" as a foreign policy strategy; it failed. So why try it again?
updated 10:27 AM EDT, Thu September 18, 2014
Van Jones says the video of John Crawford III, who was shot by a police officer in Walmart, should be released.
updated 10:48 AM EDT, Thu September 18, 2014
NASA will need to embrace new entrants and promote a lot more competition in future, argues Newt Gingrich.
updated 7:15 PM EDT, Tue September 16, 2014
If U.S. wants to see real change in Iraq and Syria, it will have to empower moderate forces, says Fouad Siniora.
updated 8:34 PM EDT, Wed September 17, 2014
Mark O'Mara says there are basic rules to follow when interacting with law enforcement: respect their authority.
updated 9:05 AM EDT, Tue September 16, 2014
LZ Granderson says Congress has rebuked the NFL on domestic violence issue, but why not a federal judge?
updated 7:49 AM EDT, Tue September 16, 2014
Mel Robbins says the only person you can legally hit in the United States is a child. That's wrong.
updated 1:23 PM EDT, Mon September 15, 2014
Eric Liu says seeing many friends fight so hard for same-sex marriage rights made him appreciate marriage.
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT