JAD: Hey, I'm Jad Abumrad.

ROBERT: I'm Robert Krulwich.

JAD: This is Radiolab. And today—do you wanna say it?

ROBERT: Uh, speed.

JAD: [laughs] See, this is a perfect example of what we've been bumping into all hour. Humans are slow. We're just too slow.

ROBERT: But now ...

LENE VESTERGAARD HAU: Yeah, hello?

ROBERT: This Lene?

LENE VESTERGAARD HAU: It is.

ROBERT: All right!

ROBERT: ... now we have a story that should make us all feel a little better.

JAD: Can I just say I didn't even think this was remotely possible what we're about to talk about.

LENE VESTERGAARD HAU: [laughs]

ROBERT: And the heroine of our story is Lene ...

LENE VESTERGAARD HAU: Vestergaard Hau.

ROBERT: That's a—is that a hyphenate?

LENE VESTERGAARD HAU: No, that—Vestergaard is my middle name. Hau is the last name, and my first name is Lene.

JAD: So Lene is a physicist at Harvard, and she has done something with speed that is just remarkable. It's the only way to say it.

LENE VESTERGAARD HAU: Well—well if we sort of step back one ...

JAD: We asked her to walk us through what she does step by step, because it's totally worth it.

LENE VESTERGAARD HAU: We start out with a clump of room temperature sodium. And at room temperature, sodium is actually a nice shiny metal.

ROBERT: Lene and her team, they take the sodium, they put it in an oven and heat it up.

LENE VESTERGAARD HAU: Exactly.

ROBERT: And as it heats up, atoms in the sodium start to vibrate faster and then faster. And when the temperature gets to around ...

LENE VESTERGAARD HAU: 350 degrees centigrade, the atoms form a vapor.

JAD: Super high pressure.

LENE VESTERGAARD HAU: And then ...

JAD: She forces the atoms into this little ...

ROBERT: ... pinhole.

LENE VESTERGAARD HAU: You have a little hole in the source.

ROBERT: So this thin stream of atoms now comes zipping out of the hole, and ...

LENE VESTERGAARD HAU: We hit them head-on with a laser beam.

ROBERT: So you bang them right in their pathway.

LENE VESTERGAARD HAU: Yes, kick them in a direction opposite to their motion.

ROBERT: And that slows them down.

LENE VESTERGAARD HAU: Exactly. And now we can load them into what we call an optical molasses.

ROBERT: Optical molasses. [laughs]

JAD: This is so baroque, I love it!

LENE VESTERGAARD HAU: In the optical molasses, the atoms will be hit by laser beams from all directions.

JAD: Is that your way of, like, saying "Don't go this way, don't go this way, don't go this way, stop!"

LENE VESTERGAARD HAU: That's right. Yes.

JAD: You corner them in from all angles.

LENE VESTERGAARD HAU: Yes. Then we can get them to really slow down.

JAD: It feels a little bit like you've enslaved these atoms. I feel bad for them.

LENE VESTERGAARD HAU: [laughs]

ROBERT: It's gonna get worse.

LENE VESTERGAARD HAU: Yes, because that's not good enough.

ROBERT: Now that she has these atoms trapped, she needs to make them sit as still as possible. So she turns off the lasers.

LENE VESTERGAARD HAU: Total darkness in the lab. And then we turn on an electromagnet. Use the fact

ROBERT: [laughs]

LENE VESTERGAARD HAU: Use the fact that the atoms are small magnets to hold them in a particular point in space so they don't all fly apart. Then we can flip the magnet of these small atoms and selectively kick out the hottest—just the hottest of them. So they will fly out of the magnet, and we just keep the lowest energy.

ROBERT: By flipping the magnets, you could say to the—there's one atom that's a little bit too jumpy, so you say, "Get out of here!"

LENE VESTERGAARD HAU: Yup. "Get out of here." Exactly.

JAD: Because you—because you want just the quietest atoms to stay.

LENE VESTERGAARD HAU: That's right.

ROBERT: So now after all this, Lene has this teeny little cloud ...

LENE VESTERGAARD HAU: 0.1 millimeter in size, typically.

ROBERT: ... of just a few million atoms.

LENE VESTERGAARD HAU: Like five, ten million.

JAD: And she says at this point, they're all very, very still. And because temperature is really just a measure of speed, really, you know, when atoms are moving quickly, we call that hot, when they're moving slowly, we call that cold, these atoms, because they're so still ...

ROBERT: These atoms are really cold. Colder than anything on Earth. Colder than the middle of empty space. Basically, these are the coldest things that have ever been cold.

LENE VESTERGAARD HAU: Yeah. And at that point, we have a totally new state of matter.

JAD: And of course, she was curious about this new state of matter.

LENE VESTERGAARD HAU: That's right. I'm a curious lady.

JAD: And now we get to the part where—well, this is the whole reason we're telling you this.

ROBERT: She now decides to ...

LENE VESTERGAARD HAU: Poke these atoms. Basically, send a light pulse in ...

ROBERT: Shoot a beam of light into this cold atom cloud ...

LENE VESTERGAARD HAU: ... and see how it reacts. You know, you have a totally ...

JAD: Why? What was it that ...

LENE VESTERGAARD HAU: Well, you know, light fascinates me.

JAD: I mean, she says, here's this thing that goes 671,000,000 miles an hour.

LENE VESTERGAARD HAU: You know, that nothing goes faster than light.

JAD: And the question just occurred to her, like, "What would happen if I took the fastest thing in the universe and stuck it into the coldest thing ever made?"

LENE VESTERGAARD HAU: Exactly. Yes.

ROBERT: So she points her laser at the atom cloud ...

LENE VESTERGAARD HAU: Aim the laser beam.

ROBERT: ... hits a switch ...

LENE VESTERGAARD HAU: So here you have this light pulse coming in.

JAD: Zooming through space.

LENE VESTERGAARD HAU: Then the front edge will reach our atom cloud ...

ROBERT: And unbelievably, the light pulse in that moment, goes ...

LENE VESTERGAARD HAU: From 186,000 miles per second to 15 miles per hour.

JAD: [laughs] Are you kidding?

LENE VESTERGAARD HAU: No!

JAD: So the light is going, like, zoom!

LENE VESTERGAARD HAU: That's right.

JAD: Wow!

LENE VESTERGAARD HAU: Inside our atom cloud!

JAD: Amazing!

ROBERT: And then it just chugs along at a leisurely speed.

LENE VESTERGAARD HAU: Something you could beat on your bicycle.

ROBERT: Yeah, you mean ride your bike faster than the light?

LENE VESTERGAARD HAU: I mean, exactly. You—you can sort of think of this race between a bicycle and a light pulse.

JAD: I mean, imagine you could just bike next to this blob of light, and you could reach out and maybe pet it a little bit, and then—pshew!—bike on ahead. But then you'd be in darkness. But you could go maybe to the edge of the cloud and wait for the light, and so that when it comes through, you could just catch it.

ROBERT: Well no, you can't catch it, because when the light gets to the other side of the atom cloud ...

LENE VESTERGAARD HAU: The—the front edge will accelerate back up to this enormous normal light speed, and then it rushes off. So it stretches out again.

JAD: Wow. Cool!

ROBERT: So here's my ...

JAD: Can you ...

ROBERT: Oh, sorry. Go ahead.

JAD: I'm sorry. So if you've got it down to 15, is that kind of like a limit? I mean, can you—can you ...

LENE VESTERGAARD HAU: We—we could bring it lower.

ROBERT: Can you stop light? Can you actually stop light?

LENE VESTERGAARD HAU: We can, yeah.

JAD: What? So that laser goes in and doesn't come out?

LENE VESTERGAARD HAU: Yes.

ROBERT: I mean, you hold it, like a ...

LENE VESTERGAARD HAU: We hold it.

JAD: How do you do that?

LENE VESTERGAARD HAU: Okay, so what we do is—it's actually...

JAD: Okay, so things get a little technical here, but basically—probably too simply—Lene has figured out a way to tweak the properties of this atom cloud.

ROBERT: She can make it like a brick that light bounces off of, or she can make it clear so light cruises through.

JAD: In this case, what she does is she shoots the light into the atom cloud ...

LENE VESTERGAARD HAU: So we slow it down.

JAD: And then right at that moment, as it's chugging along ...

LENE VESTERGAARD HAU: Chug chug chug at 15 miles an hour.

ROBERT: ... she tweaks the atom cloud to make it, well, thick.

LENE VESTERGAARD HAU: And the light pulse will say, "Oops!" It'll come to a halt.

ROBERT: …almost like it's frozen in a block of ice.

LENE VESTERGAARD HAU: In this ...

JAD: Oh, so it just sits?

LENE VESTERGAARD HAU: Mm-hmm, yes. It just sits.

JAD: Wow!

ROBERT: When—when you realized what you'd done, did you do a little jig or what did you ...

LENE VESTERGAARD HAU: Oh, yes. That was amazing. It's like sitting in the lab, of course, in the middle of the night, and just knowing, "Whoa, you're the first one who has been in this part of nature." Yeah, it was joy. You know, of course, to some extent, I'm an engineer, but this whole idea that I can take this light pulse and bring it down to a human scale, that's something you just, at a very personal level, get excited about. This is more like, you know—I mean, you can sort of say, you know, like—like a sculptor will create a beautiful sculpture.

JAD: For me as I was thinking about this, I actually think of it in terms of painting. Like Vermeer, you know, the painter?

ROBERT: Hmm.

JAD: Like, he could create this illusion that light was just suspended there on the canvas, just shimmering. Like he somehow captured the light. But that was just an illusion. Lene actually did it.

LENE VESTERGAARD HAU: Mm-hmm. Yes.

JAD: Do you ever—do you ever wonder—do you ever, like, you know, after this night, you walk out and into the—well, I imagine next day, and the sun is shining, and you just look at the light, and you think, "Ha ha ha! I've got your number!"

ROBERT: You're like Zeus, you know? You could be Zeus for a moment.

LENE VESTERGAARD HAU: Uh-huh. Uh-huh. And also perhaps being Scandinavian, right? Where we love the light around midsummer.

JAD: Yeah, you have a whole lot of it. Or then a whole lot ...

ROBERT: Then a whole lot not.

LENE VESTERGAARD HAU: Yeah. Yeah.

JAD: Maybe you could do something about that. Maybe you could store the light.

LENE VESTERGAARD HAU: Hold it up for the wintertime.

JAD: You could store it up, and then you could unleash the cloud, and suddenly there would be sunshine when there was darkness.

LENE VESTERGAARD HAU: So save it—save it for the wintertime, yes?

JAD: Yeah!

ROBERT: Well, we've been doing this for a number of years, but this has to be one of the more remarkable conversations we've ever had.

JAD: Thank you very much. This was wonderful.

ROBERT: Thank you. Yeah, it really is.

LENE VESTERGAARD HAU: But you—but you didn't get to the real important stuff, though.

ROBERT: Oh, wait!

JAD: What, what, what, what, what?

LENE VESTERGAARD HAU: So we—we can play a trick. The trick is we can stop and extinguish the light pulse in one part of space and revive it in a totally different location.

ROBERT: You mean you can transport ...

JAD: You can transport it?

LENE VESTERGAARD HAU: Yeah.

JAD: At this point, we were like, "What weird-ass science fiction movie did we just slip into?"

ROBERT: Lene says when the light hit those atoms back in her cloud there ...

LENE VESTERGAARD HAU: The light pulse cloud will create a little imprint in the atoms.

JAD: It's like if you were to punch soft clay with your hand, and then you could see the imprint of your knuckles there in the clay.

ROBERT: That's what happens when the light hits those atoms.

LENE VESTERGAARD HAU: The light pulse will change the atoms a little bit. That's how it imprints its information in the atoms.

ROBERT: And according to Lene, that imprint is like a physical impression of the light. All the information about the light, its frequency, energy, whatever ...

JAD: All that stuff is copied.

LENE VESTERGAARD HAU: In the atoms.

ROBERT: So there's a shadow of light? I mean, what does that mean?

LENE VESTERGAARD HAU: It's a shadow of light, yes. And now we can pull that imprint out, so now what we have out in free space is a perfect matter copy.

ROBERT: You mean like physical matter?

LENE VESTERGAARD HAU: Yes. And then we can move that around. We can put it on the shelf or we can move it around. We can squish it, and then we can take it over ...

JAD: She says if she wants to, she can then make a few tweaks to the cloud.

LENE VESTERGAARD HAU: Then the light pulse will come back to life, propagate slowly through the cloud, and then exit and speed back up.

JAD: So you could store—I mean, if you were—if you were President Obama and you said, "I would like to put the light around me right now in a time capsule for later generations to experience," he could take it using your process, put it in an archive somewhere, and then ...

LENE VESTERGAARD HAU: Put it in a bottle. Mm-hmm.

JAD: And 1,000 years later, they would—they would know the light that surrounded him.

LENE VESTERGAARD HAU: Yes.

ROBERT: No!

JAD: That's what she said. That's what she just said!

ROBERT: No, I know she did. Yeah. That's—how would you know the difference? Light is the same. How do you know oh, that's the same light?

LENE VESTERGAARD HAU: It's contained in my matter copy that preserves the information.

ROBERT: So when the new light turns on, it identically copies the light from before in a way that—that makes it as—as specific as saying that's Mary Kay Jones again, or whatever.

LENE VESTERGAARD HAU: Yes. Yes. That's right.

ROBERT: Oh, man.

LENE VESTERGAARD HAU: I've also—also—also wondered about, you know—because we could—in our lab in Cambridge, we could send a light pulse and stop it, extinguish it, make our little matter copy, put it in a bottle. I could put it in a suitcase say, bring it to Copenhagen, turn it into light. But I've thought about also, how do I get that bottle through security in the airport?

JAD: What would it look like? Would it just be a bottle full of—full of emptiness?

LENE VESTERGAARD HAU: It would be a vacuum, but there would be a little clump of atoms in there.

JAD: It would have to be less than three ounces of atoms, or they would have ...

LENE VESTERGAARD HAU: Well, yes.

ROBERT: It would be so much less than three ounces. Yeah, you could just walk through the airport. You've got no problems there.

LENE VESTERGAARD HAU: Okay.

JAD: Or you can open it and be like, "You wanna see something cool?" Pew! Blind him.

ROBERT: That would probably be also against the law.

LENE VESTERGAARD HAU: Yes, yes, yes.

JAD: How am I gonna get my light through security?

[ANSWERING MACHINE: Message six. New.]

[LISTENER: Hi, Christian Rivest, former Radiolab intern, calling in with the credits. I actually don't have enough credits on this phone to try and do this again very fast. Well, I'll try really, really fast. Radiolab is produced by Jad Abumrad. Our staff includes Ellen Horne, Soren Wheeler, Pat Walters, Tim Howard, Brenna Farrel, Molly Webster, Melissa Dunn, Dylan Keefe. All right guys, this is harder than I thought.]

[CHRIS BERUBE: Chris Berube, that's me!]

[LISTENER: Kelsey Padgett, Thanks to Josh Lopina, Scott ...]

[JOHN MAINSTONE: And Kraftwerk.]

[LISTENER: And special thanks to Alan Pierson and the Brooklyn Philharmonic. Even though I just read that very, very fast, this call probably cost me about $20. I hope you guys use it on the air. Bye.]

[ANSWERING MACHINE: End of message.]

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