Honor Harger: A history of the universe in sound

40,579 views ・ 2011-06-23

TED


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Space,
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we all know what it looks like.
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We've been surrounded by images of space
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our whole lives,
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from the speculative images
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of science fiction
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to the inspirational visions of artists
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to the increasingly beautiful pictures
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made possible by complex technologies.
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But whilst we have
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an overwhelmingly vivid
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visual understanding of space,
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we have no sense of what space sounds like.
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And indeed, most people associate space with silence.
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But the story of how
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we came to understand the universe
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is just as much a story of listening
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as it is by looking.
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And yet despite this,
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hardly any of us have ever heard space.
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How many of you here
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could describe the sound
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of a single planet or star?
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Well in case you've ever wondered,
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this is what the Sun sounds like.
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(Static)
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(Crackling)
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(Static)
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(Crackling)
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This is the planet Jupiter.
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(Soft crackling)
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And this is the space probe Cassini
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pirouetting through the ice rings of Saturn.
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(Crackling)
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This is a a highly condensed clump
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of neutral matter,
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spinning in the distant universe.
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(Tapping)
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So my artistic practice
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is all about listening
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to the weird and wonderful noises
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emitted by the magnificent celestial objects
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that make up our universe.
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And you may wonder,
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how do we know what these sounds are?
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How can we tell the difference
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between the sound of the Sun
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and the sound of a pulsar?
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Well the answer
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is the science of radio astronomy.
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Radio astronomers
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study radio waves from space
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using sensitive antennas and receivers,
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which give them precise information
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about what an astronomical object is
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and where it is in our night sky.
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And just like the signals
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that we send and receive here on Earth,
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we can convert these transmissions into sound
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using simple analog techniques.
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And therefore, it's through listening
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that we've come to uncover
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some of the universe's most important secrets --
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its scale, what it's made of
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and even how old it is.
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So today, I'm going to tell you a short story
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of the history of the universe through listening.
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It's punctuated
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by three quick anecdotes,
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which show how accidental encounters
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with strange noises
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gave us some of the most important information
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we have about space.
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Now this story doesn't start
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with vast telescopes
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or futuristic spacecraft,
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but a rather more humble technology --
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and in fact, the very medium
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which gave us the telecommunications revolution
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that we're all part of today:
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the telephone.
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It's 1876, it's in Boston,
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and this is Alexander Graham Bell
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who was working with Thomas Watson
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on the invention of the telephone.
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A key part of their technical set up
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was a half-mile long length of wire,
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which was thrown across the rooftops
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of several houses in Boston.
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The line carried the telephone signals
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that would later make Bell a household name.
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But like any long length of charged wire,
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it also inadvertently became
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an antenna.
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Thomas Watson
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spent hours listening
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to the strange crackles and hisses
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and chirps and whistles
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that his accidental antenna detected.
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Now you have to remember,
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this is 10 years before
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Heinrich Hertz proved the existence of radio waves --
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15 years before Nikola Tesla's four-tuned circuit --
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nearly 20 years before Marconi's first broadcast.
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So Thomas Watson wasn't listening to us.
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We didn't have the technology
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to transmit.
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So what were these strange noises?
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Watson was in fact listening
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to very low-frequency radio emissions
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caused by nature.
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Some of the crackles and pops were lightning,
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but the eerie whistles
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and curiously melodious chirps
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had a rather more exotic origin.
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Using the very first telephone,
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Watson was in fact
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dialed into the heavens.
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As he correctly guessed,
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some of these sounds were caused
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by activity on the surface of the Sun.
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It was a solar wind
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interacting with our ionosphere
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that he was listening to --
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a phenomena which we can see
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at the extreme northern and southern latitudes of our planet
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as the aurora.
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So whilst inventing the technology
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that would usher in the telecommunications revolution,
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Watson had discovered
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that the star at the center of our solar system
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emitted powerful radio waves.
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He had accidentally been the first person
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to tune in to them.
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Fast-forward 50 years,
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and Bell and Watson's technology
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has completely transformed
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global communications.
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But going from slinging some wire
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across rooftops in Boston
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to laying thousands and thousands of miles of cable
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on the Atlantic Ocean seabed
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is no easy matter.
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And so before long,
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Bell were looking to new technologies
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to optimize their revolution.
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Radio could carry sound without wires.
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But the medium is lossy --
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it's subject to a lot of noise and interference.
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So Bell employed an engineer
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to study those noises,
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to try and find out where they came from,
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with a view towards building
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the perfect hardware codec, which would get rid of them
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so they could think about using radio
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for the purposes of telephony.
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Most of the noises
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that the engineer, Karl Jansky, investigated
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were fairly prosaic in origin.
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They turned out to be lightning
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or sources of electrical power.
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But there was one persistent noise
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that Jansky couldn't identify,
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and it seemed to appear
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in his radio headset
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four minutes earlier each day.
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Now any astronomer will tell you,
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this is the telltale sign
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of something that doesn't originate from Earth.
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Jansky had made a historic discovery,
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that celestial objects could emit radio waves
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as well as light waves.
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Fifty years on
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from Watson's accidental encounter with the Sun,
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Jansky's careful listening
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ushered in a new age of space exploration:
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the radio astronomy age.
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Over the next few years,
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astronomers connected up their antennas to loudspeakers
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and learned about our radio sky,
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about Jupiter and the Sun,
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by listening.
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Let's jump ahead again.
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It's 1964,
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and we're back at Bell Labs.
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And once again,
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two scientists have got a problem with noise.
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Arno Penzias and Robert Wilson
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were using the horn antenna
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at Bell's Holmdel laboratory
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to study the Milky Way
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with extraordinary precision.
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They were really listening
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to the galaxy in high fidelity.
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There was a glitch in their soundtrack.
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A mysterious persistent noise
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was disrupting their research.
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It was in the microwave range,
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and it appeared to be coming
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from all directions simultaneously.
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Now this didn't make any sense,
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and like any reasonable engineer or scientist,
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they assumed that the problem must be the technology itself,
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it must be the dish.
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There were pigeons roosting in the dish.
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And so perhaps once they cleaned up the pigeon droppings,
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get the disk kind of operational again,
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normal operations would resume.
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But the noise didn't disappear.
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The mysterious noise
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that Penzias and Wilson were listening to
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turned out to be the oldest and most significant sound
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that anyone had ever heard.
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It was cosmic radiation
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left over from the very birth of the universe.
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This was the first experimental evidence
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that the Big Bang existed
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and the universe was born at a precise moment
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some 14.7 billion years ago.
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So our story ends
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at the beginning --
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the beginning of all things, the Big Bang.
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This is the noise that Penzias and Wilson heard --
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the oldest sound that you're ever going to hear,
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the cosmic microwave background radiation
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left over from the Big Bang.
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(Fuzz)
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Thanks.
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(Applause)
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