Sounds of the Universe The Sky at Night

Hello and welcome to the Jodrell Bank Radio Observatory,

home to the giant Lovell Telescope.

In this programme, we are going to explore new perspectives

because we are going to be listening to the sounds of the cosmos.

It sounds bizarre, but we are going to be bringing you

weird and wonderful noises from right across the universe

including something that's never been heard before.

Coming up, Lucie Green reveals

how it is possible to see sounds on a distant star.

There it is. That is what I've been after.

We'll find out how sound waves sculpted

the beautiful and complex universe that we see around us.

That's the universe, 300,000 years after the big bang.

What do you reckon?

-That sounded like a car going past or something, didn't it?

-It did a bit.

I'll be talking with Tim O'Brien

about one of the most evocative sounds in the universe.

-Here we go.

-I can see something coming through.

'The sound of a star that has collapsed in on itself.'

-It's like a heartbeat.

-Exactly.

We'll discover how to take amazing images of the night sky

with just a mobile phone.

The moon. That is amazing too. Wow!

Everyone knows that in space no-one can hear you scream,

and that is technically true.

In the vacuum of space, sound waves can't travel.

But there is plenty of sound in space.

Imagine the crackling of lightning amongst the clouds of Jupiter.

Imagine the whisper of the wind on Mars.

All those sounds are trapped.

To access them, we have to use our imaginations, our theories

and our equations.

By listening to these sounds,

we get a new perspective on what's out there

and see things that were previously hidden, even in our own star.

There is a problem with the sun.

When you look at it, you see what appears to be a broiling

and beautiful surface

but all the real action is happening deep beneath that surface.

In fact, using sound is the only way that we can delve

beneath that surface and see what is going on internally.

That's just what Lucie Green has been doing.

Our seemingly silent sun is actually alive with sound.

These are the genuine sounds of our star,

sped up to bring them into the range of human hearing.

They're generated from deep below its surface

and are a vital tool that's helped us understand its inner workings.

I love listening to the sounds of the sun.

They are so alien and they evoke a totally different character,

a different side to the sun than the one I normally see

when I'm studying it.

The fact that we can listen to the sun at all is incredible.

Between us and the sun is 93 million miles of essentially empty space.

It is a vacuum out there

and the sounds of the sun can't travel directly to us.

Our ability to hear it and everything that we've learned

along with that comes down to the very nature of what sound is.

Sat here, I'm surrounded by sound -

voices, clinking of cups, the whoosh of the coffee machine.

All these sounds are created by the same basic process -

vibrations.

Vibrations that pass through the air to our ears.

And the same is true within the sun.

Turbulent regions of gas create sound on an epic scale.

But it appears silent to us because there is no medium,

no air or gas to transport the noise.

However, we can detect these sounds

because if you know the trick, it's possible to see sound.

What we need is something called a Chladni plate and some salt.

Give it a good covering.

PLATE REVERBERATES

You immediately see that the salt is starting to move.

It is starting to take on a pattern.

There it is, that is what I've been after.

The salt takes on a pattern when I make the sound.

The vibrations of the plate are creating the sound that

goes into my ears and it is also moving the salt around.

You can see that with each note I play, the pattern changes.

Oh, beautiful.

That is the key thing about these plates.

The patterns that are created are unique for the particular sound

and that means that even if I can't hear the sound,

I can't hear the effect of those vibrations,

I know what notes are being created by looking at the pattern.

And it's that principle that allows us

to tap into the sounds of our star.

What I have here is an image of the sun

taken by the Solar Dynamics Observatory

and it's a colour-coded image.

The black regions show us where gas is falling away from us

and the white region is where the gas is rising up.

It creates a very complex pattern.

Essentially, it's exactly the same as we made here

with our Chladni plates.

Now, it may seem hard to believe,

but we can extract from this rather messy image

the very particular patterns

that are associated to particular notes inside the sun.

That is how we reconstruct the sounds that the sun has.

What's truly fascinating is that through studying these sounds

we can get a snapshot of the internal workings of our star...

..thanks to work by people like Bill Chaplain.

DEEP NOTE PLAYS

-OK, that must be one of the big pipes.

-Yes.

Straight away, we can tell just from the low tones, low pitch,

the low frequency of that that that's one of the biggest pipes.

The frequencies at which pipes resonate, that tells us

something about the size of the pipes,

but also something about the gas inside the pipes.

How does that relate to the sun

and what we see as surface vibrations of the sun?

The sun makes the sound naturally

and it's trapped within the body of the sun, just in the same way

that sound is trapped within the body of the pipes here.

So the trapped sound makes the sun resonate

but because the sun is a big ball of gas,

the sound makes the sun gently breathe in and out.

So we don't actually listen to the sun literally, what we do is,

we are seeing the visible manifestation, if you like,

of the sound trapped inside.

Crucially, sound is affected by what it's travelling through.

The changing temperature,

density, even magnetic fields found in different parts of the sun

all affect properties like the speed of sound trapped inside.

And detecting these changes reveals the inner structure.

It's a technique known as helioseismology.

We knew that a sun-like star should have a core

where we're burning hydrogen into helium.

That's what's powering the star, driving its evolution.

Then the outer parts of the sun, there we have conviction,

so where we're moving energy from one place to the other

literally by moving hot gas.

But it was with helioseismology that we got the first measure,

direct measurement of the depth of that outer convective layer.

Also, we can measure the rate at which the material is spinning,

and the profile that was found, actually,

was not the one that theoreticians had predicted would be there.

So that information that we've got on the rotation of the sun

has been really important for people who are trying to understand

how all of the magnetic activity, all of the magnetic structures,

how those are generated on the sun.

What I find amazing is that, by looking at the patterns

on the surface of the sun,

we can not only listen to the sounds of the sun,

we can also delve deep underneath its surface

and we can track and predict its future activity.

It's an insight that would simply be beyond us

if it wasn't for the music of our star.

There are sounds throughout the cosmos

but, depending on where you are, not all sounds sound the same.

We're used to sound travelling through

the atmosphere of the Earth, but we can think about

what sound would be like on other planets, as well.

We have some software from the University of Southampton

that will let us take our voices and send them to Venus,

so I think we should give that a go.

I'm going to give you the microphone.

Great, I get the microphone.

I'm going to press record, and you say something, OK?

So, what would my voice sound like on other planets?

Well, good question!

Well, the software will now process this.

So this is based on atmosphere, density, various other parameters?

That's right.

VERY DEEP VOICE: 'So what would my voice sound like on other planets?'

You sound like me! That's actually pretty close!

I feel like a space invader or something - "Take us to your leader!"

What's happening there is two things.

The atmosphere on Venus is this dense mix of carbon dioxide

and a bit of sulphuric acid, so not a good place to be.

But that density changes the way your vocal cords vibrate

and also how the sound's transmitted,

because the speed of sound is different.

So it's just like in water, sound actually travels faster,

so the more dense the atmosphere, the quicker the sound will travel,

and therefore you get a change in the voice.

But that was quite distinctive, wasn't it?

Yeah, absolutely, it does illustrate this point

that what you sound like depends on where in the solar system you are.

Now, we're here at Jodrell Bank,

and the focus of much of the research done from this facility

is on pulsars.

Pulsars are extraordinary stars that emit beams of radiation

that make them appear to flash.

The team here at Jodrell are hoping that they will help them

to solve one of the great mysteries of astronomy.

To study them, they use the massive Lovell Telescope.

Its dish is over 75 metres wide

and it observes the cosmos using radio waves.

So, Tim, we're there to look at pulsars,

but pulsars are a special case of a neutron star.

I find neutron stars a bit freaky,

because it's something about one and a half times the mass of the sun,

-that could fit in Sheffield.

-Exactly, yes.

It's a dead star, it's the core of an exploded star,

so when the star explodes in the supernova, the core collapses

to make this incredibly dense object.

These things, the exciting thing for us

is that these things are spinning, but we can see them

because they actually beam out light -

and in our case we're interested in the radio waves they beam out -

from the magnetic poles.

And just like the Earth, you know the Earth's magnetic north

-and magnetic south are offset...

-Yes.

..with respect to the sort of north pole,

the same is true for the neutron star,

so as it spins, the magnetic poles sweep around like that,

and that means that the beam that comes out from them

sweeps around the sky.

And every time it comes past us, we see a flash.

-So just like a lighthouse.

-Exactly, it's a cosmic lighthouse

spinning in the sky.

We see flash, flash, flash from the pulsar.

And we're going to demonstrate that live with the Lovell Telescope now,

so I don't know, I think Ian, our telescope controller,

will move the telescope on source.

Fantastic.

If you come and have a look at the screen over here, basically,

we've turned those radio waves into a sound

and we can listen to that noise.

STATIC CRACKLES

And then what will happen

as the telescope gradually swings onto the pulsar...

-Oh, here we go.

-I can see something coming through.

REGULAR THUDDING

-And that's it?

-That's it.

-That's the pulsar?

That's the pulsar spinning.

Spinning around, sending that beam, that radio beam into space?

And you can hear the...

dum, dum, dum, dum, dum, dum...

-It's like a heartbeat?

-Yeah, exactly.

That is a dead star, weighing more than the sun,

spinning about three times a second, 26,000 light years away,

which is really exciting because, actually,

we've only just set the system up for you today

to listen to this pulsar now.

It is fantastic.

THUDDING CONTINUES

So pulsars seem to be fascinating, but why are they useful?

Yeah. I mean, they're actually, this...

I'll turn that down so we can talk.

The key role is in testing extreme physics.

One of the key projects that we're using that the pulsar group here

and elsewhere in the world are working on with telescopes like this

at the moment is to use pulsar to try and detect gravitational waves.

I think you should say "The elusive gravitational wave."

I definitely should!

These things were predicted by Einstein 100 years ago,

but we've not yet directly detected them.

They're actually really bizarre things,

they're ripples in space-time.

So if you can imagine somewhere on the other side of the universe

there's two massive black holes at the centre of the galaxy,

say two galaxies have merged.

These black holes are spiralling around one another.

They produce this expanding pattern of ripples in space...

-The gravitational waves?

-Exactly, the gravitational waves

travel through space at the speed of light.

If there was one coming through us now,

which there almost certainly is,

we're gradually being stretched in one direction,

and perpendicular to that we're being squashed.

So I suppose that's quite a distinctive signature to pick up?

It is. It's what you would look for.

You might imagine that what you'd look for is whether something

is simply longer or shorter as the gravitational wave goes past,

but the trouble is, the amount by which space is stretched

is tiny, so in the case of the ones we're trying to pick up

with the pulsars, it's a bit like the distance

between the Earth and the moon being changed

-by about one hundredth of the width of a human hair.

-Oooh!

-It is accuracy.

-The measurement is very hard to do.

What's key about pulsars in this case is,

they're very stable clocks, effectively,

so we heard the thud, thud, thud, thud of the pulsar,

three times a second.

Because you've got so much mass spinning at that speed,

it's a very stable system.

What sort of accuracy are we talking?

We're talking about measuring those periods to an accuracy

of basically a nanosecond, so a billionth of a second.

As space is squashed and stretched as a gravitational wave passes by,

those pulses are bunched together or stretched apart.

-So you'll see a slight change in the timing of those pulses?

-Exactly.

-So when do you think you'll see one?

-Yeah, this is the key.

Sometime in the next few years

we might well detect a gravitational wave.

In a sense, it's a risk.

We're learning things as we go along,

as we gather more and more data, but, yeah,

great hope for this technique.

I think that's fantastic, thank you so much.

Next, Pete Lawrence has ventured outside to bring us his star guide.

But first, he's going to show us how to take fabulous images

of the night sky with something many of us have in our pockets.

All you need is one of these, a telescope,

and something as simple as this -

a smartphone with a camera in it.

Now, you might not think that the camera on a smartphone

is sensitive enough to be able to take astronomical photographs,

but it is, especially if the target is big and bright.

Now, the one thing which really fits that bill perfectly

is, of course, the moon.

'To see details on the moon's surface, you need shadows,

'so you'll get the best images when the moon isn't full.'

'Start by holding the phone away from the eyepiece.'

Then I'm going to move it in close and closer,

following the bright dot down.

'This is actually a bit trickier than it looks

'because of the way the lenses in the phone and the eyepiece interact,

'but keep at it.'

-There it goes. And I can just take a shot.

-CAMERA CLICKS

And, oh, that's a nice one.

Look at that.

And I'm actually quite pleased with that, it's quite a nice image.

There are lots of amazing things to see on the surface of the moon,

and to find a selection of the best,

check out the moon guides on our website...

'For the last few days, some members

'of the Breckland Astronomical Society have been experimenting

'with smartphone photography.

'They've even managed to capture an image of Jupiter.'

-Wow! That is...

-It's not too bad. It shows up.

But you've got the main belts coming through there,

and I bet that if the great red spot were visible on that disc,

you would actually pick that up.

-I reckon I would have got it, yeah.

-Which is amazing.

But the other thing that comes out, because Jupiter is a gas planet

which rotates very rapidly, it's squashed, so it looks

not like a circle, it looks like the circle has been squashed,

and you can actually pick that out on that,

very clearly, actually, that the planet looks less wide

from top to bottom than it is from left to right.

Incredible. Absolutely amazing result.

Ah, the moon! One of my favourite objects.

That is amazing, too! Wow!

It was a four inch refractor.

Look at that, that is just incredible.

You know, a few years ago you would have taken a picture

with a digital camera and you'd have been very happy with that.

And this is with a smartphone.

The hardest part I found, of course, is trying to get it lined up

and get it centred. Hold it steady enough to get a steady image.

That's it, isn't it? Yeah.

Well, that is quite a fantastic image.

-You should be very proud of that.

-Thank you.

-Thank you very much.

Now, there's lots of interest in this month's night sky,

but I think the highlights have to be the planets.

Here is my star guide to what's coming up.

As darkness falls on the 16th,

Jupiter is due south,

two thirds of the way up the sky.

If you have a telescope,

look at Jupiter's disc between 10:30pm

and just past midnight to see a rare event.

The shadows of Io and Ganymede,

two of Jupiter's large Galilean moons,

will be crossing the planet.

In the hours following midnight,

locate the Plough, which is overhead.

Follow the natural curve of its handle

away from the pan to locate

the bright orange star, Arcturus.

Continue the curve to arrive at brilliant white Spica.

The bright, salmon pink object above Spica is Mars.

A little less than two outstretched hands to the left

and slightly below Spica is the yellow-hued planet Saturn.

On 27th March

there is also a daytime treat.

Using your eyes, try to find the moon at 9:20 in the morning,

being careful not to look at the sun.

Five moon-widths below the crescent,

Venus will be shining away in the blue sky.

Well, now back to sound.

Tim has created an audio tour of the universe for us,

including some things that no-one's ever heard before.

Tim, where shall we start?

The plan is to start close and then work our way out.

We'll start with Jupiter, and these are sounds from signals

that the Voyager 1 spacecraft recorded as it passed by Jupiter.

Let's have a listen.

WHINING AND WHISTLING

I don't think I expected that.

No, it does sound a bit like a dawn chorus.

-It does.

-But screechier!

-It's a rather more erratic...

-Pterodactyls or something!

Yeah, rather than lovely hummingbirds.

No, it's actually called the Jovian chorus, the Jupiter chorus.

These chorus waves are actually produced by electrons

that are spiralling around the magnetic field of Jupiter,

so from the north magnetic pole to the south magnetic pole,

and as they spiral around they produce these radio waves

that we've turned into a sound here.

SOUND CONTINUES

So we can hear this delightful noise!

I think we've probably heard enough Jupiter.

-Excellent, good.

-Turned off on cue.

Where shall we go next?

We're going to actually stick with Voyager, actually.

We're going to carry on with Voyager back until just a few years ago,

when Voyager left the heliosphere,

basically the edge of the volume of space

that's influenced by the sun.

WAVERING HIGH TONE

What you're hearing is the rate of cosmic ray particles

hitting the detectors on Voyager.

So, high-pitched, lots of particles.

-TONE DROPS SUDDENLY BOTH:

-Whoa!

-That's quite significant!

-And that was it.

That was the point at which it left the heliosphere.

And that marks the end of our solar system, effectively.

Yeah, so those particles are sort of trapped by the magnetic field

of the sun, and as it passed over that invisible boundary, actually,

where those particles are gathered, then you hear the flux,

the numbers of those cosmic rays drop significantly,

which you heard in the sound there.

I find it fantastic, because Voyager was launched in 1977,

travelling at 10.5 miles a second out to the edge of the solar system,

and now it is officially beyond.

Our first interstellar messenger, basically.

And still sending back information.

But, Tim, I want to ask you about your own research,

because something rather exciting happened just a few weeks ago.

So I spend a lot of my time working on things called novae.

We now know they're stars exploding and becoming very bright

and one of these popped up in the constellation of Scorpius

just a few weeks ago, and we've been monitoring it

with telescopes around the world.

Actually, what we'll play now is the sound of the data

-from an x-ray telescope on board the Swift spacecraft.

-OK.

STEADY HIGH-PITCHED TONE

LOWER TONE GROWS IN INTENSITY

LOWER TONE FADES

Come on, you're grinning. Tell us what you heard.

-Let you in on the secret.

-So there's two distinct tones there, I think.

There are, yeah, and what you're hearing are basically the x-rays

coming from this explosion,

and there's actually two dominant parts to the x-ray emission.

So, first of all, what you heard was a high-frequency tone.

That comes from the shockwave that's ripping out from this explosion

through the wind of the red giant star that's in this system,

and that produces high-energy x-rays

which come into that sound as a high-pitched tone.

So this is just ripping through the material

-that's surrounding the white dwarf?

-Exactly, yeah.

So the explosion happens to the white dwarf,

the shockwave expands out, very hot gas,

very high-energy x-rays that you hear as the high-pitched tone.

As that expands out you start to see through it,

and what you see is the surface of the hot white dwarf

that's left behind in the centre where the explosion occurred.

That also produces x-rays, but it's rather cooler,

they're rather lower energy x-rays,

and that comes in as the lower frequency tone.

And that actually dominates, that becomes very bright for a while,

but then as the hot gas on the white dwarf is all used up,

then that fades away and then, coming back, underneath it all

you hear the high pitch of the shockwave still expanding

out into interstellar space.

Excellent. Well, I'm glad we heard it and we've now travelled

to a distant star, but we need to go much further than that,

to the edge of the observable universe,

because sound waves that once echoed there

formed everything that we see around us today.

Sound waves are a key part

of one of the most famous images in science -

the cosmic microwave background, or CMB.

This is the oldest light left in the universe, and it forms a picture

of what the cosmos was like only 300,000 years after the big bang.

To discuss the role of sound waves that we can see in the CMB,

I'm meeting Sarah Bridle,

and I've brought with me an interesting recording.

We're going to talk about the early universe,

which was a very different place

from the one we see around us today, so what was it like?

Well, so, early in the universe the universe was much denser.

So, basically, today we've got a vacuum in space.

But if we go back in time to the early universe

the universe was much smaller, everything was much closer together,

and we had this soup of elementary particles,

protons, electrons and neutrons,

and they're all much closer together.

That means you can get sound travelling through the universe.

Right, so today the universe is virtually a vacuum,

but back then the sound waves

could propagate through this dense medium.

Excellent - if you had any sound waves.

-So what we need is a source of sound.

-OK, yes.

Then some patches were clumpier than others,

so there is more stuff in one place and less in somewhere else.

Then gravity comes in.

As things pull together, then they heat up,

so the universe is getting clumpier and hotter

in this patch of the universe.

And then, actually, it gets so hot that it pushes itself apart again.

Just because the particles are moving.

The particles are moving and it's getting hotter,

and the pressure of that heat pushes it apart again,

and then gravity pulls it back in again, pressure pushes it apart.

So we've got this oscillation,

this wobbling going on in the early universe, which is a sound wave.

So I've actually got a recording

-of what the sound would have been like at that point.

-Right.

We've moved it up 50 octaves so we can hear it,

it's a very low note, but we've moved it up

so I hope you find this impressive.

WHOOSHING

There you go, that's the universe 300,000 years after the big bang.

What do you reckon?

-Well, that sounded like a car going past, didn't it?

-It did a bit!

It's a complicated noise, though.

To see them we have to tune ourselves

into the microwave region of the spectrum.

Right, so at that time the light is travelling around

in the early universe and it's optical light,

so we could see it with our eyes.

If you were standing there. It's not advised!

It wouldn't be very nice, so we shouldn't go there.

But it's light, like we can see with our eyes,

but now, as the universe has expanded,

those light waves have stretched out, and so they become microwaves,

and so we can look with special radio telescopes at these microwaves

and we can see a picture of the light which is coming towards us,

that's been travelling to us all that time

since the universe was just 300,000 years old.

And we've got that picture here,

so this is a picture of the whole sky taken by Planck,

which is the European satellite

that's just made the best ever map of this light.

What can we see here and how does it relate

to what we were just talking about?

Well, we can see these sound waves. We're taking a snapshot,

basically, of what these sound waves were like in the early universe.

We can see these red and blue patches.

So where the red patches are, that's where the universe

was hotter and denser, really clumped together,

and then that patch would have expanded afterwards,

but the blue patches here are where it was cooler and more spread out.

So, in fact, those hot patches where there's lots of stuff,

that would have then gone on to form the first stars

and galaxies that we can see today.

So this is a recent image.

Planck delivered its results a year or so ago now.

Is there more to learn from looking at the microwave background

in the early universe?

Well, Planck also has polarised sunglasses, effectively, on it,

so we're going to learn about the direction of the light,

which will tell us even more about

how much stuff there is in the universe.

Fab. Well, I hope you'll come back and tell us about that,

and you never know,

we might have found a more aesthetically pleasing recording

of the early universe by then.

-Thanks a lot.

-Thanks a lot.

That's it for now, but do remember to send your smartphone pictures in

and we'll put them up on our website.

When we come back next month we'll be talking about Mars

and what ten years of robots roving around the planet have told us.

And Mars is really prominent in the sky at the moment,

so remember, get outside and get looking up.

Good night.