What does the universe sound like A musical tour Matt Russo
I’d like you all
to close your eyes, please …
and imagine yourself sitting
in the middle of a large, open field
with the sun setting on your right.
And as the sun sets,
imagine that tonight
you don’t just see the stars appear,
but you’re able to hear the stars appear
with the brightest stars
being the loudest notes
and the hotter, bluer stars
producing the higher-pitched notes.
(Music)
And since each constellation
is made up of different types of stars,
they’ll each produce
their own unique melody,
such as Aries, the ram.
(Music)
Or Orion, the hunter.
(Music)
Or even Taurus, the bull.
(Music)
We live in a musical universe,
and we can use that to experience
it from a new perspective,
and to share that perspective
with a wider range of people.
Let me show you what I mean.
(Music ends)
Now, when I tell people
I’m an astrophysicist,
they’re usually pretty impressed.
And then I say I’m also a musician –
they’re like, “Yeah, we know.”
(Laughter)
So everyone seems to know
that there’s this deep connection
between music and astronomy.
And it’s actually a very old idea;
it goes back over 2,000 years
to Pythagoras.
You might remember Pythagoras
from such theorems
as the Pythagorean theorem –
(Laughter)
And he said:
“There is geometry
in the humming of the strings,
there is music in the spacing
of the spheres.”
And so he literally thought
that the motions of the planets
along the celestial sphere
created harmonious music.
And if you asked him,
“Why don’t we hear anything?”
he’d say you can’t hear it
because you don’t know
what it’s like to not hear it;
you don’t know what true silence is.
It’s like how you have to wait
for your power to go out
to hear how annoying
your refrigerator was.
Maybe you buy that,
but not everybody else was buying it,
including such names as Aristotle.
(Laughter)
Exact words.
(Laughter)
So I’ll paraphrase his exact words.
He said it’s a nice idea,
but if something as large and vast
as the heavens themselves
were moving and making sounds,
it wouldn’t just be audible,
it would be earth-shatteringly loud.
We exist, therefore
there is no music of the spheres.
He also thought that the brain’s
only purpose was to cool down the blood,
so there’s that …
(Laughter)
But I’d like to show you that in some way
they were actually both right.
And we’re going to start by understanding
what makes music musical.
It may sound like a silly question,
but have you ever wondered why it is
that certain notes, when played together,
sound relatively pleasing or consonant,
such as these two –
(Music)
while others are
a lot more tense or dissonant,
such as these two.
(Music)
Right?
Why is that? Why are there notes at all?
Why can you be in or out of tune?
Well, the answer to that question
was actually solved by Pythagoras himself.
Take a look at the string on the far left.
If you bow that string,
it will produce a note as it oscillates
very fast back and forth.
(Musical note)
But now if you cut the string in half,
you’ll get two strings,
each oscillating twice as fast.
And that will produce a related note.
Or three times as fast,
or four times –
(Musical notes)
And so the secret to musical harmony
really is simple ratios:
the simpler the ratio,
the more pleasing or consonant
those two notes will sound together.
And the more complex the ratio,
the more dissonant they will sound.
And it’s this interplay
between tension and release,
or consonance and dissonance,
that makes what we call music.
(Music)
(Music ends)
(Applause)
Thank you.
(Applause)
But there’s more.
(Laughter)
So the two features of music
we like to think of as pitch and rhythms,
they’re actually two versions
of the same thing,
and I can show you.
(Slow rhythm)
That’s a rhythm right?
Watch what happens when we speed it up.
(Rhythm gets gradually faster)
(High pitch)
(Lowering pitch)
(Slow Rhythm)
So once a rhythm starts happening
more than about 20 times per second,
your brain flips.
It stops hearing it as a rhythm
and starts hearing it as a pitch.
So what does this have to do
with astronomy?
Well, that’s when we get
to the TRAPPIST-1 system.
This is an exoplanetary system
discovered last February of 2017,
and it got everyone excited
because it is seven Earth-sized planets
all orbiting a very near red dwarf star.
And we think that three of the planets
have the right temperature
for liquid water.
It’s also so close
that in the next few years,
we should be able to detect
elements in their atmospheres
such as oxygen and methane –
potential signs of life.
But one thing about
the TRAPPIST system is that it is tiny.
So here we have the orbits
of the inner rocky planets
in our solar system:
Mercury, Venus, Earth and Mars,
and all seven Earth-sized
planets of TRAPPIST-1
are tucked well inside
the orbit of Mercury.
I have to expand this by 25 times
for you to see the orbits
of the TRAPPIST-1 planets.
It’s actually much more similar in size
to our planet Jupiter and its moons,
even though it’s seven
Earth-size planets orbiting a star.
Another reason this got everyone excited
was artist renderings like this.
You got some liquid water,
some ice, maybe some land,
maybe you can go for a dive
in this amazing orange sunset.
It got everyone excited,
and then a few months later,
some other papers came out
that said, actually,
it probably looks more like this.
(Laughter)
So there were signs
that some of the surfaces
might actually be molten lava
and that there were very damaging
X-rays coming from the central star –
X-rays that will sterilize the surface
of life and even strip off atmospheres.
Luckily, just a few months ago in 2018,
some new papers came out
with more refined measurements,
and they found actually
it does look something like that.
(Laughter)
So we now know that several of them
have huge supplies of water –
global oceans –
and several of them
have thick atmospheres,
so it’s the right place to look
for potential life.
But there’s something even more
exciting about this system,
especially for me.
And that’s that TRAPPIST-1
is a resonant chain.
And so that means for every two orbits
of the outer planet,
the next one in orbits three times,
and the next one in four,
and then six, nine, 15 and 24.
So you see a lot of very simple ratios
among the orbits of these planets.
Clearly, if you speed up their motion,
you can get rhythms, right?
One beat, say, for every time
a planet goes around.
But now we know if you speed
that motion up even more,
you’ll actually produce musical pitches,
and in this case alone,
those pitches will work together,
making harmonious,
even human-like harmony.
So let’s hear TRAPPIST-1.
The first thing you’ll hear will be
a note for every orbit of each planet,
and just keep in mind,
this music is coming
from the system itself.
I’m not creating the pitches or rhythms,
I’m just bringing them
into the human hearing range.
And after all seven planets have entered,
you’re going to see –
well, you’re going to hear a drum
for every time two planets align.
That’s when they kind of
get close to each other
and give each other a gravitational tug.
(Tone)
(Two tones)
(Three tones)
(Four tones)
(Five tones)
(Six tones)
(Seven tones)
(Drum beats)
(Music ends)
And that’s the sound of the star itself –
its light converted into sound.
So you may wonder
how this is even possible.
And it’s good to think
of the analogy of an orchestra.
When everyone gets together
to start playing in an orchestra,
they can’t just dive into it, right?
They have to all get in tune;
they have to make sure
their instruments resonate
with their neighbors' instruments,
and something very similar happened
to TRAPPIST-1 early in its existence.
When the planets were first forming,
they were orbiting within a disc of gas,
and while inside that disc,
they can actually slide around
and adjust their orbits to their neighbors
until they’re perfectly in tune.
And it’s a good thing they did
because this system is so compact –
a lot of mass in a tight space –
if every aspect of their orbits
wasn’t very finely tuned,
they would very quickly
disrupt each other’s orbits,
destroying the whole system.
So it’s really music
that is keeping this system alive –
and any of its potential inhabitants.
But what does our solar system sound like?
I hate to be the one to show you this,
but it’s not pretty.
(Laughter)
So for one thing,
our solar system
is on a much, much larger scale,
and so to hear all eight planets,
we have to start with Neptune
near the bottom of our hearing range,
and then Mercury’s going
to be all the way up
near the very top of our hearing range.
But also, since our planets
are not very compact –
they’re very spread out –
they didn’t have to adjust
their orbits to each other,
so they’re kind of just all playing
their own random note at random times.
So, I’m sorry, but here it is.
(Tone)
That’s Neptune.
(Two tones)
Uranus.
(Three tones)
Saturn.
(Four tones)
Jupiter.
And then tucked in, that’s Mars.
(Five tones)
(Six tones)
Earth.
(Seven tones)
Venus.
(Eight tones)
And that’s Mercury –
OK, OK, I’ll stop.
(Laughter)
So this was actually Kepler’s dream.
Johannes Kepler is the person
that figured out
the laws of planetary motion.
He was completely fascinated by this idea
that there’s a connection
between music, astronomy and geometry.
And so he actually spent an entire book
just searching for any kind of musical
harmony amongst the solar system’s planets
and it was really, really hard.
It would have been much easier
had he lived on TRAPPIST-1,
or for that matter …
K2-138.
This is a new system
discovered in January of 2018
with five planets,
and just like TRAPPIST,
early on in their existence,
they were all finely tuned.
They were actually tuned
into a tuning structure
proposed by Pythagoras himself,
over 2,000 years before.
But the system’s actually
named after Kepler,
discovered by the Kepler space telescope.
And so, in the last few billion years,
they’ve actually lost their tuning,
quite a bit more than TRAPPIST has,
and so what we’re going to do
is go back in time
and imagine what
they would’ve sounded like
just as they were forming.
(Music)
(Music ends)
(Applause)
Thank you.
Now, you may be wondering:
How far does this go?
How much music actually is out there?
And that’s what I was wondering last fall
when I was working
at U of T’s planetarium,
and I was contacted by an artist
named Robyn Rennie and her daughter Erin.
Robyn loves the night sky,
but she hasn’t been able
to fully see it for 13 years
because of vision loss.
And so they wondered
if there was anything I could do.
So I collected all the sounds
I could think of from the universe
and packaged them into
what became “Our Musical Universe.”
This is a sound-based planetarium show
exploring the rhythm
and harmony of the cosmos.
And Robyn was so moved
by this presentation
that when she went home,
she painted this gorgeous
representation of her experience.
And then I defaced it
by putting Jupiter on it for the poster.
(Laughter)
So …
in this show, I take people
of all vision levels
and bring them on an audio tour
of the universe,
from the night sky all the way out
to the edge of the observable universe.
But even this is just the start
of a musical odyssey
to experience the universe
with new eyes and with new ears,
and I hope you’ll join me.
Thank you.
(Applause)