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 or Orion the Hunter
or even Taurus the Bull 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 rider
range of people let me show you what I
mean now when I tell people I'm an
astrophysicist are usually pretty
impressed and then I say I'm also a
musician they're like yeah we know
so everyone seems to know that there's
this deep connection between music and
astronomy and it's actually a very old
idea goes back over two thousand years
to Pythagoras
you might remember Pythagoras from such
theorems as the Pythagorean theorem and
he said there's geometry in the humming
of the strings there's 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
kind of like how you have to wait for
your power to go out to hear how
annoying that your refrigerator was
maybe you buy that but not everybody
else was buying it including such names
as Aristotle exact words 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 brains
only purpose was to cool down the blood
so there's that but I'd like to show you
that in some way they were actually both
right and we're gonna 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 too
why is that why are there notes at all
why can you be in or out of tune well
the answer that question was actually
solved by Pythagoras himself take a look
at the string on the far left if you bow
that string it'll produce a note as it
oscillates very fast back and forth but
now if you cut the string in half you'll
get two strings each oscillating twice
as fast and that'll produce a related
note or three times as fast or four
times and so the secret to musical
harmony really is simple ratios the
simpler the ratio the more pleasing or
constant 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 consonants and dissonance
that makes what we call music
[Applause]
[Music]
[Applause]
[Music]
thank you but there's more so the two
features of music we like to think of as
pitch and rhythms there are actually two
versions of the same thing and I can
show you
that's a rhythm right watch what happens
when we speed it up
[Music]
so once the 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 one 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 then
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
one 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 one planets it's actually much
more similar in size to our planet
Jupiter and its moons even though it's
seven earth sized planets orbiting a
star another reason this got everyone
excited was artists renderings like this
we've got some liquid water some some
ice maybe some land if you can go for a
dive in this amazing orange sunset 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
services 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 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
right place to look for the search for
potential life but there's something
even more exciting about this system
especially for me and that's the
Trappist one 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 4 and
then 6 9 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 pictures will work together
making harmonious even human-like
harmony so let's hear Trappist one 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 gonna
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
you
[Music]
[Applause]
[Music]
[Applause]
[Music]
[Applause]
and that's the sound of the star itself
it's 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 one early
in its existence when the planets were
first forming they were orbiting within
a disc of gas and well inside that disk
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 the 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 well what is our solar
system sound like I hate to be the one
to show you this but it's not pretty 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 is 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 far
Frawley 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 here it is it's Neptune
Uranus Saturn
Jupiter and then tucked in that's that's
Mars Earth
Venus
[Applause]
and that's mercury okay so this was
actually Kepler's dream Johannes Kepler
is the person that figured out the laws
of planetary motion and 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 one 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 two thousand years before but the
systems 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 gonna do is go back in time and
imagine what they would have sounded
like just as they were for me
[Applause]
[Music]
[Laughter]
[Music]
[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 fault when I was working at U of
T's planetarium and I was contacted by
an artist named Robin Rennie and her
daughter Erin and Robin loves the night
sky but she hasn't been able to fully
see it for thirteen years because of
vision loss and so they wondered if
there was anything I could do and 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 Robin was so moved by this
presentation that when she went home she
painted this gorgeous representation of
her experience and then I'd effaced it
by putting Jupiter on it and for the
poster 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 a start of a musical Odyssey to
experience the universe with new eyes
and with new years and I hope you'll
join me thank you
[Music]