Copyright ©2008 NPR. For personal, noncommercial use only. See Terms of Use. For other uses, prior permission required.

STEVE INSKEEP, host:

You know, we make a lot of noise here on Earth with our radio broadcasts and TV broadcasts. And some of that noise slips out into space, which raises the question of how far our signals travel. Comes back to an old question: whether there's intelligent life in the universe and if there is could it be listening to us.

NPR's Robert Krulwich decided to try to find out.

(Soundbite of TV show, "I Love Lucy")

(Soundbite of music)

Ms. LUCILLE BALL (As Lucy Ricardo): So why don't you join the thousands of happy, pappy people and get a great big bottle of mitameatamegamin(ph).

(Soundbite of laughter)

(Soundbite of "I Love Lucy" theme song)

ROBERT KRULWICH: Fifty-seven years ago, CBS introduced "I Love Lucy" to America. The program was broadcast. That means it was sent through the air and traveled across the country, but not like this really.

(Soundbite of "I Love Lucy" theme song)

More compressed into fast-moving waves like this.

(Soundbite of distorted music)

Mr. CHRIS IMPEY (Astronomer, University of Arizona): Yeah, it moves into electromagnetic waves.

KRULWICH: Which, says astronomer Chris Impey, were beamed from transmitters in the East and then bounced from receiver to receiver across the country.

Mr. IMPEY: And they travel at pretty much light speed.

KRULWICH: Until Lucy's signal hit your TV antennae at home and got switched back into…

Soundbite of TV show, "I Love Lucy")

Ms. LUCILLE BALL: Mitavitameatamin.

(Soundbite of laughter)

KRULWICH: But some of those Lucy waves passed through our houses and bounced off the Earth.

Mr. IMPEY: And then eke out into space.

KRULWICH: And the speed of light. So how long did it take for Lucy's signal to go from the east coast to say Chicago?

Mr. IMPEY: Oh, that's probably a microsecond.

KRULWICH: And then how about out to the moon?

Mr. IMPEY: About a second and a half.

KRULWICH; And then to Mars?

Mr. IMPEY: Mars is some number of minutes, Jupiter's probably an hour, and five hours to the edge of the solar system.

KRULWICH: Five hours and she's left the solar system. Wow. So if that wave has been carrying…

(Soundbite of TV show, "I Love Lucy")

Mr. DESI ARNAZ (As Ricky Ricardo): Lucy!

KRULWICH: …across space all this time, where is Lucy now?

Mr. IMPEY: It's traveled for 57 years, so it's traveled 57 light years. That's a good hard number. Miles? So 57 light years is about 200 trillion miles. Two hundred trillion miles from the Earth. Pretty impressive.

KRULWICH: Yeah. Does that mean her signal has passed by a couple of hundred stars by now?

Mr. IMPEY: Yes, many of which will probably have Earth-like planets around them. So that's interesting.

KRULWICH: Yeah, because somebody light years from here right now could be trying to figure out what is happening to this poor Earth creature.

Soundbite of TV show, "I Love Lucy")

Ms. LUCILLE BALL: Oh, Ethel, my wedding ring is someplace in this barbeque.

KRULWICH: And then they'll have to know what a barbecue is and also what a laugh is, if they can even hear a laugh.

Mr. IMPEY: Yeah, what's left of her laugh. I guess. We have to…

KRULWICH: (Unintelligible)

Mr. IMPEY: …the brutal truth.

KRULWICH: OK. So here is the brutal truth.

(Soundbite of explosion echoing)

It goes back to the Big Bang that helped create our universe. This is our imaginary version, but the echo of that event says Chris Impey can still be detected today. It's a low, faint hum.

Mr. IMPEY: The microwave hum or a static hum of microwave…

KRULWICH: That scientists see on radiometers wherever they look.

Mr. IMPEY: Everywhere in space. You can't get away from it. You can't get around it. You can't suppress it.

KRULWICH: But when Lucy's signal first left the Earth it was strong. It was louder than the echo of the Big Bang.

Mr. IMPEY: Oh, yeah.

KRULWICH: Until she was subject to a basic law of physics.

Mr. IMPEY: The Inverse Square Law.

KRULWICH: Right. Which says…

Mr. IMPEY: Basically, the strength of the signal goes down as the square of the distance.

KRULWICH: Which means that very quickly as she moves away from Earth, Lucy's signal…

(Soundbite of TV show, "I Love Lucy")

Ms. BALL: That vitameatavegamin.

KRULWICH: …gets softer…

(Soundbite of TV show, "I Love Lucy")

Ms. BALL: That vitameatavegamin.

KRULWICH: …and softer…

(Soundbite of TV show, "I Love Lucy")

Ms. BALL: That vitameatavegamin.

KRULWICH: …and softer until she becomes indistinguishable from the deep hum of the universe. So yes, technically Lucy's wave is still out there. It's still traveling. But in effect, she has disappeared into the echo of the Big Bang.

Mr. IMPEY: Yes, she has.

KRULWICH: And even the cleverest aliens imaginable, says Chris Impey, would not be able to find her, because to find her signal buried in the hum of the universe…

Mr. IMPEY: Is just beyond any technology we can imagine to pick it up.

KRULWICH: So they're not going to hear Lucy?

Mr. IMPEY: They're not going to Lucy.

KRULWICH: So then when does Lucy, in fact, disappear? How far out…

Mr. IMPEY: Out to where will we hear Lucy?

KRULWICH: Yeah.

Mr. IMPEY: Really not too far beyond the edge of the solar system.

KRULWICH: Really? So she doesn't get much past Pluto. That is such a piddley -and it's even worse than that, say Chris Impey. Because while there were a whole lot of television signals slipping into space in the 1950s and '60s…

(Soundbite of TV show "The Mickey Mouse Club")

Mouseketeers: (Singing) We're the Mouseketeers…

KRULWICH: And '70s and '80s…

(Soundbite of theme song from "The Tonight Show")

The Earth was a noisy place for a while. So if you were an alien passing by you'd think what's going on down there.

(Soundbite of music)

But more recently, as we earthlings have become more technologically sophisticated, we take our signals and we turn them into narrow beams. We aim them at satellites.

Mr. IMPEY: With microwave transmitters we actually direct the signals point-to-point across the surface of the Earth. We direct the signals up to satellites and then bounce them back down.

KRULWICH: And we don't boom them out like we used to. Instead, we compress them into fiber optic cables.

Mr. IMPEY: It's a very efficient way to carry signals.

KRULWICH: But then no one gets to hear that stuff.

Mr. IMPEY: No one gets to hear that.

KRULWICH: And so, since the 1990s, the volume of sound bouncing off our planet - our accidental noise - has gone down.

Mr. IMPEY: We have become probably, orders of magnitude, quieter in terms of radio leakage than 20 or 30 years ago.

KRULWICH: So the fact of our being here, the noise of us, not only can't be heard much beyond the solar system, more and more of what we say can't be heard at all.

Mr. IMPEY: Yes. We're a little quieter now.

KRULWICH: And as for the notion that we have radio and we have TV and we have culture and surely somebody out there's going to notice us…

Mr. IMPEY: And, you know, we tend to feel that our technology and our muscular ability to send signals around the planet really does make us special and therefore noticeable. But not actually. We're not that noticeable.

(Soundbite of theme song from "Sesame Street")

Space is incredibly large and we're sort of just dropped in the void.

KRULWICH: Where the loudest noises that we make turn out to be barely a peep.

(Soundbite of echoing)

Robert Krulwich, NPR News, New York.

INSKEEP: The Podcast Krulwich on Science is at npr.org/podcasts.

It's MORNING EDITION from NPR News. I'm Steve Inskeep

RENEE MONTAGNE, host:

And I'm Renee Montagne.

Copyright © 2008 NPR. All rights reserved. No quotes from the materials contained herein may be used in any media without attribution to NPR. This transcript is provided for personal, noncommercial use only, pursuant to our Terms of Use. Any other use requires NPR's prior permission. Visit our permissions page for further information.

NPR transcripts are created on a rush deadline by a contractor for NPR, and accuracy and availability may vary. This text may not be in its final form and may be updated or revised in the future. Please be aware that the authoritative record of NPR's programming is the audio.

Comments

 

Please keep your community civil. All comments must follow the NPR.org Community rules and terms of use, and will be moderated prior to posting. NPR reserves the right to use the comments we receive, in whole or in part, and to use the commenter's name and location, in any medium. See also the Terms of Use, Privacy Policy and Community FAQ.