Valentine's Gold Comes from Space
BILL WOLFF (Announcer): This is NPR.
ALISON STEWART, host:
Of course today is Valentine's Day and for those lucky enough to have someone to give them chocolate or flowers or a stuffed animal or a really nice new computer - Manoli, her husband Lawrence did that. Here's a bit of advice on what you should not do. Do not ask, where did this gift came from. That question could be especially tricky especially if your valentine is NPR's esteemed science correspondent Robert Krulwich. If you ask Robert where something came from, be warned. He may give you a very, very long answer.
ROBERT KRULWICH: So let's say you buy your sweetheart something nice and Valentiney - made of gold. And she says this.
Unidentified Woman: Oh, it's lovely. Where did it come from?
KRULWICH: And then you say, well, do you want the short answer or do you want the long answer?
Unidentified Woman: Oh, I think I'd like the long answer.
KRULWICH: Okay. Since you asked. The gold in this necklace comes from a star.
Unidentified Woman: Oh, Robert.
KRULWICH: No, I mean it. The gold I'm giving you today was made in the center of a star.
Unidentified Woman: No.
Dr. NEIL deGRASSE TYSON (Astrophysicist; Director, Hayden Planetarium, New York City): That's what stars do.
Dr. TYSON: They're in the business of cosmic alchemy.
KRULWICH: That is Neil deGrasse Tyson, director of the Hayden Planetarium in New York City. And since you were interested, I asked him...
Unidentified Woman: You did?
KRULWICH: Yeah, to tell me how gold gets made like from the very beginning. Like what do you need?
Dr. TYSON: Okay. First you need a universe. Is that starting early?
KRULWICH: That's good. That's good.
Dr. TYSON: That's good. We're on the right track.
Unidentified Woman: Oh, no.
KRULWICH: Shhh. When the universe began, he says, they were just two kinds of atoms - very simple. Hydrogen, which has one proton in its nucleus, and helium with two protons.
Dr. TYSON: And that's pretty much all she wrote at the beginning of the universe.
KRULWICH: And the thing is you can't smush these different atoms together to make a new kind of atom with three protons, or with four proton or five protons because unless you apply a lot of heat, protons don't like each other. They will not combine.
Dr. TYSON: Usually, they'll resist each other because of the same charge. Okay?
KRULWICH: So how hot to you have to make it to get two protons who don't like each other to sit together?
Dr. TYSON: About 10 million degrees.
KRULWICH: Which just happens to be the temperature you find inside a star. So, in our sun right now, it is so hot that two protons that would normally say I really, really don't like you are being slammed together so hard finally each one says okay.
Dr. TYSON: Now I really, really, really like you.
(Soundbite of laughter)
KRULWICH: This is called fusion. So in our sun, hydrogen atoms are being slammed together to become helium. Later helium atoms are going to be slammed together to become carbon. The sun is a furnace that slams protons into heavier and heavier atoms.
Dr. TYSON: And then it keeps going because carbon and oxygen and nitrogen is silicon and it goes, it just plows its way up the periodic table of elements.
KRULWICH: So carbon has six protons; nitrogen, seven protons; oxygen, eight protons. A hot sun can cook all the way up to a 26 proton atom, that's iron. But when it gets to iron, says Neil Tyson, that is about as far as it can go,
Dr. TYSON: It's this - it's kind of dead. It's dead matter. You can't fuse it. You can fusion it.
KRULWICH: SO for a start, when you hit iron, you start to run out of fuel. You can't cook and that's trouble.
Dr. TYSON: That's a bad day for the star. And at that moment, the entire collapses and in that collapse the start reaches stratospheric temperatures and blows its guts to smithereens.
(Soundbite of explosion)
KRULWICH: This is what's called a supernova. When a big star, bigger than our sun explodes - now you wouldn't actually hear this in outer space because you can't hear things out there. But it's so cataclysmic and so powerful you can see a supernova across the universe. They outshine full galaxies because the atoms inside are slamming so furiously into each other, creating heat that is so intense.
Dr. TYSON: Oh, oh, hundreds of millions of degrees.
KRULWICH: That only in a supernova is it possible to create atoms with 30 protons or 40 protons, or 50 protons, or 60 protons. And while nature prefers even numbers for stability, every so often a star will forge also an odd numbered atom like gold.
Dr. TYSON: Gold is number 19. It's odd.
KRULWICH: So there aren't a lot of gold atoms when you compare different sorts of atoms?
Dr. TYSON: There is about a million iron atoms for every gold atom in the universe.
KRULWICH: And then after this explosion, those lonely gold atoms are cast deep into the universe and they hang around for a long, long time until a few of them might join in the cloud and may become a planet and once inside the planet, they migrate near the surface where we can dig them up. But every atom of gold in Neil Tyson's wedding ring, which is a lot of atoms, right?
Dr. TYSON: It's been a while since I've counted, but I agree. Yes, it's got scads of atoms.
KRULWICH: Everyone of them was forged in a collapsing star, traveled across the universe to get to his finger.
And my very last question is how many years are represented by your gold ring? How many miles did the gold have to travel to get to you?
Dr. TYSON: Oh, bajillions.
(Soundbite of laughter)
KRULWICH: Well, I thought we could get a slightly harder number than that. So I asked Dr. Tyson to calculate the distance a gold atom would travel from its birth in a supernova through space to his wedding ring.
Dr. TYSON: So what do we get? We get 3 million light-year journey.
KRULWICH: To your finger.
Dr. TYSON: To end up as the expression of someone's love.
KRULWICH: All that distance just for you.
Unidentified Woman: For me?
KRULWICH: Yeah, yeah, for you.
Robert Krulwich, NPR News, in New York.
MARTIN: Robert Krulwich is definitely our Valentine. We like him so much. He's going to make another appearance on this show very shortly. It involves (unintelligible), a guy named Pavarotti Skywalker. Stay tuned.
STEWART: And just for the record, the story you heard was not an Emergency Krulwich. Regular listeners of BRYANT PARK know we always have a Krulwich story ready to go in case a guest drops out or hanging with seven minutes of dead air. But for the record, this does not set our Krulwich count back to zero. Today, knock wood, we've gone 19 days without having to deploy Krulwich, an emergency. We just chose to do that.
MARTIN: I don't care.
STEWART: This is THE BRYANT PARK PROJECT from NPR News.