How to pronounce "hisses"

Space,

we all know what it looks like.

We've been surrounded by images of space

our whole lives,

from the speculative images

of science fiction

to the inspirational visions of artists

to the increasingly beautiful pictures

made possible by complex technologies.

But whilst we have

an overwhelmingly vivid

visual understanding of space,

we have no sense of what space sounds like.

And indeed, most people associate space with silence.

But the story of how

we came to understand the universe

is just as much a story of listening

as it is by looking.

And yet despite this,

hardly any of us have ever heard space.

How many of you here

could describe the sound

of a single planet or star?

Well in case you've ever wondered,

this is what the Sun sounds like.

(Static)

(Crackling)

(Static)

(Crackling)

This is the planet Jupiter.

(Soft crackling)

And this is the space probe Cassini

pirouetting through the ice rings of Saturn.

(Crackling)

This is a a highly condensed clump

of neutral matter,

spinning in the distant universe.

(Tapping)

So my artistic practice

is all about listening

to the weird and wonderful noises

emitted by the magnificent celestial objects

that make up our universe.

And you may wonder,

how do we know what these sounds are?

How can we tell the difference

between the sound of the Sun

and the sound of a pulsar?

Well the answer

is the science of radio astronomy.

Radio astronomers

study radio waves from space

using sensitive antennas and receivers,

which give them precise information

about what an astronomical object is

and where it is in our night sky.

And just like the signals

that we send and receive here on Earth,

we can convert these transmissions into sound

using simple analog techniques.

And therefore, it's through listening

that we've come to uncover

some of the universe's most important secrets --

its scale, what it's made of

and even how old it is.

So today, I'm going to tell you a short story

of the history of the universe through listening.

It's punctuated

by three quick anecdotes,

which show how accidental encounters

with strange noises

gave us some of the most important information

we have about space.

Now this story doesn't start

with vast telescopes

or futuristic spacecraft,

but a rather more humble technology --

and in fact, the very medium

which gave us the telecommunications revolution

that we're all part of today:

the telephone.

It's 1876, it's in Boston,

and this is Alexander Graham Bell

who was working with Thomas Watson

on the invention of the telephone.

A key part of their technical set up

was a half-mile long length of wire,

which was thrown across the rooftops

of several houses in Boston.

The line carried the telephone signals

that would later make Bell a household name.

But like any long length of charged wire,

it also inadvertently became

an antenna.

Thomas Watson

spent hours listening

to the strange crackles and hisses

and chirps and whistles

that his accidental antenna detected.

Now you have to remember,

this is 10 years before

Heinrich Hertz proved the existence of radio waves --

15 years before Nikola Tesla's four-tuned circuit --

nearly 20 years before Marconi's first broadcast.

So Thomas Watson wasn't listening to us.

We didn't have the technology

to transmit.

So what were these strange noises?

Watson was in fact listening

to very low-frequency radio emissions

caused by nature.

Some of the crackles and pops were lightning,

but the eerie whistles

and curiously melodious chirps

had a rather more exotic origin.

Using the very first telephone,

Watson was in fact

dialed into the heavens.

As he correctly guessed,

some of these sounds were caused

by activity on the surface of the Sun.

It was a solar wind

interacting with our ionosphere

that he was listening to --

a phenomena which we can see

at the extreme northern and southern latitudes of our planet

as the aurora.

So whilst inventing the technology

that would usher in the telecommunications revolution,

Watson had discovered

that the star at the center of our solar system

emitted powerful radio waves.

He had accidentally been the first person

to tune in to them.

Fast-forward 50 years,

and Bell and Watson's technology

has completely transformed

global communications.

But going from slinging some wire

across rooftops in Boston

to laying thousands and thousands of miles of cable

on the Atlantic Ocean seabed

is no easy matter.

And so before long,

Bell were looking to new technologies

to optimize their revolution.

Radio could carry sound without wires.

But the medium is lossy --

it's subject to a lot of noise and interference.

So Bell employed an engineer

to study those noises,

to try and find out where they came from,

with a view towards building

the perfect hardware codec, which would get rid of them

so they could think about using radio

for the purposes of telephony.

Most of the noises

that the engineer, Karl Jansky, investigated

were fairly prosaic in origin.

They turned out to be lightning

or sources of electrical power.

But there was one persistent noise

that Jansky couldn't identify,

and it seemed to appear

in his radio headset

four minutes earlier each day.

Now any astronomer will tell you,

this is the telltale sign

of something that doesn't originate from Earth.

Jansky had made a historic discovery,

that celestial objects could emit radio waves

as well as light waves.

Fifty years on

from Watson's accidental encounter with the Sun,

Jansky's careful listening

ushered in a new age of space exploration:

the radio astronomy age.

Over the next few years,

astronomers connected up their antennas to loudspeakers

and learned about our radio sky,

about Jupiter and the Sun,

by listening.

Let's jump ahead again.

It's 1964,

and we're back at Bell Labs.

And once again,

two scientists have got a problem with noise.

Arno Penzias and Robert Wilson

were using the horn antenna

at Bell's Holmdel laboratory

to study the Milky Way

with extraordinary precision.

They were really listening

to the galaxy in high fidelity.

There was a glitch in their soundtrack.

A mysterious persistent noise

was disrupting their research.

It was in the microwave range,

and it appeared to be coming

from all directions simultaneously.

Now this didn't make any sense,

and like any reasonable engineer or scientist,

they assumed that the problem must be the technology itself,

it must be the dish.

There were pigeons roosting in the dish.

And so perhaps once they cleaned up the pigeon droppings,

get the disk kind of operational again,

normal operations would resume.

But the noise didn't disappear.

The mysterious noise

that Penzias and Wilson were listening to

turned out to be the oldest and most significant sound

that anyone had ever heard.

It was cosmic radiation

left over from the very birth of the universe.

This was the first experimental evidence

that the Big Bang existed

and the universe was born at a precise moment

some 14.7 billion years ago.

So our story ends

at the beginning --

the beginning of all things, the Big Bang.

This is the noise that Penzias and Wilson heard --

the oldest sound that you're ever going to hear,

the cosmic microwave background radiation

left over from the Big Bang.

(Fuzz)

Thanks.

(Applause)