one of the oldest questions ever asked
by humanity is are we alone and the
modern version of this question that
astronomers are asking is how do we scan
the heavens to find out so in the next
18 minutes I want to bring bring you on
a grand tour of how modern Astra EXO
planet astronomers I’m sorry
attempting to address this very old
question you should take three things
away from my talk the first is that we
the exoplanet astronomers are the modern
descendants of Giordano Bruno whom I’ll
tell you about in a moment the second is
a paradox we seem to know much less
about nearby stars and their exoplanets
than those they are very far away and
the third is that for the first time in
human history we have a way of scanning
worlds very far away to tell you about
possible signs of life so my story or
our story starts with Giordano Bruno who
live in the 16th century
Giordano Giordano was a iconoclast
meaning that he really liked to piss
people off and he was eventually
executed for heresy but not before
making the following statement which is
there are countless suns and countless
earths all rotating around their Suns in
exactly the same way as the planets of
our system you need to appreciate that
this was a very radical statement at a
time in human history you could get into
a lot of trouble for saying this but
Enza he was right it turns out that if
you just stare stars in the sky by dumb
luck some of these stars will have
planets that pass in front of them that
cause a little tiny dip in the light
called a transit and this is the method
by which the Kepler space telescope has
discovered thousands of planets orbiting
other stars beyond our solar system
known as exoplanets here’s a way to
visualize these discoveries so I’m
showing you a chart in which I’m showing
the size of the exoplanet of Units
versus the orbital period in days and so
the earth on this chart would have a
size of 1
and a period of 365 days immediately you
see two surprises the first surprise is
that there seems to be a population of
exoplanets with roughly the size of our
Jupiter but orbiting with periods of a
few days and not twelve years
this means that their atmospheres are
really hard thousands of degrees hot but
my father the bigger surprise at least
to me is that there are exoplanets with
sizes between that of Neptune there is
no such planet in our solar system no
example of such a super earth and this
teaches you a very important lesson
which is that if you would like to
understand exoplanets in the nearby
universe you can’t just look in the
solar system you need to look beyond
here’s another surprise you may be
surprised to know that in our cosmic
neighborhood the Sun is actually not a
typical star a typical stars rather is
dimmer and is cooler in temperature and
they are usually called
red dwarfs not so far away is a red
dwarf called Trappist one and very
recently just in the last few months
astronomers including my colleagues at
been discovered seven of size or smaller
exoplanets orbiting the Trappist one
star in a very tight configuration in
fact the configuration is so tight that
you can fit the entire system within the
orbit of mercury in our solar system but
because trap is one is cooler than the
Sun is half the temperature is still
possible that even though they are so
close that some of these exoplanets
could have water on their rocky surfaces
and they’re really the only way to tell
is to study the atmospheres of these
planets so I just tell you that we have
discovered thousands of exoplanets but
the reality is that only a handful of
them are close enough for us to study
their atmospheres and here’s a way to
visualize that challenge I’m going to
show you a chart again of the size of
the exoplanet again in of units by now
I’m going to show you the distance away
in parsecs so a parsec is three
lightyears
light-year is the distance that light
travels in one year it’s a very vast
distance just just to give you a sense
of how fast this is it takes like one
second to go from here to the moon so a
light is a very large distance the first
thing you see is that the Kepler
discoveries in blue are very far away a
few hundred to a thousand parsecs much
too far for us to study their
atmospheres and tell you if their water
or carbon dioxide and so on there’s a
new NASA telescope called tests which
I’ll tell you about in a few minutes
that will discover exoplanets ten times
closer so we have a fighting chance of
studying their atmospheres but by but by
far the most interesting exoplanets are
the ones there are tens of parsecs away
and I just tell you about track this one
and the reason why trap is what is
interesting is because if you look at
the chart track this one has the planets
the seventh planet of Troubles one have
roughly the size of Earth that almost 10
parsecs away very close almost our
carbon our cosmic garden and the sizes
of these circles indicate how easy or
difficult it is to detect the transit so
large circle means easy to detect
transits so they have large circles
that’s good but they say that’s a
paradox in this graph which is why is
this region empty so the region between
us and ten parsecs is empty and it’s
surprising because the test statistics
tell us to expect thousands of
exoplanets and yet this region is nearly
empty why is that just think about it
right it’s a paradox because we know
less about about the exoplanet
population around nearby stars then we
know around faraway stars the paradox
comes about because of something called
the bright star paradox so if I was
using a telescope on earth to look at a
star with an exoplanet what I’m really
interested in is the tiny dip in light
that the transit causes but because I’m
observing through the atmosphere of
Earth which is turbulent the turbulence
typically creates a signal that’s
comparable to or larger than the signal
of the transit so to check my discovery
I have to point the telescope at a
so-called reference
a starter is roughly the same brightness
roughly the same type roughly the same
temperature and not too far away but the
problem is that bright stars are very
rare in the sky so it’s very rare almost
impossible to find a bright star a
bright reference star next to the bright
star you’re interested in and this is
the reason why we know almost nothing
about exoplanets around bright stars how
do you overcome this problem you
overcome this problem by placing your
telescopes in space above the Earth’s
atmosphere so that you don’t have to
worry about reference stars so in the
next few minutes I’m gonna tell you
about three space telescopes they have
either launched or will launch in the
next few years that will revolutionize
our understanding of exoplanets around
nearby stars the first telescope as I
promised is called the tests mission of
NASA tests just launched a few months
ago successfully on a falcon 9 rocket
it’s now in space taking data we will
see the results very soon and the
strategy of tests is to do an all-sky
survey so we will look at every patch of
sky but the price to pay for such white
coverage is that test will only look at
each patch for 27 days this means that
the exoplanets that test will find will
have our two periods of roughly a week
the next Space Telescope I will tell you
about is called ke ops this is our local
pride and joy is a space mission of the
European Space Agency or ISA is that by
Switzerland we are paying 30% of the
bill and in fact it’s lab at the
University of Bell and the strategy of k
ops is a little bit different it’s not
doing the all-sky survey the test is
doing rather K Ops is looking at golden
targets that we found to be interesting
in the past there are additional hints
of showing interesting exoplanets and we
would like to detect the really
interesting ones that we can follow up
to stay there amis fears together the
two space missions Tess and K ops would
deliver a treasure trove of the most
interesting exoplanets in the nearby
universe that we can then study their
atmospheres so I keep saying atmospheres
but how do you really study the
atmosphere
excellent you do it by you take the
light from an exoplanet and you split it
into different colors it’s called a
spectrum is analogous to taking the
fingerprint of a person so given good
enough data and if you spread the light
across enough colors you can distinguish
between say water and carbon dioxide in
this example I’m showing you and the
Space Telescope that would do this
really really well it’s the most
expensive one ever built by humanity
this is the James Webb Space Telescope
they were launched in 2021 so I’ve told
you how to detect exoplanets around
bright stars I’ve described to you how
to take their spectral fingerprints the
next logical step is how do we use these
techniques to tell if there’s life on an
exoplanet that’s the big question
right and the answer is that I would
like to identify a molecule that is not
only uniquely associated with life but
that can accumulate in large amounts in
the atmosphere and exist in the form of
a gas so I can detect it using a
telescope and I can look at in the
spectrum this is called a bio signature
unfortunately many of the gases produced
by life our soup reduced by rocks
geology so the methane produced by this
cow would be may as well come from the
ground I can’t really tell so the
challenge of bio signatures is how do I
detect signs of biology in the face of
geological false positives that’s the
challenge the traditional view of bio
signatures is that there’s a magic
molecule that will tell me once and for
all on all exoplanets in the universe
when I have life the modern view or bio
signatures is that there’s no such magic
molecule instead you have to detect a
family of molecules you have to assess
the environment from which these
molecules emerge the atmosphere then you
have we would have to assign a
probability as to where these fam this
family of molecules is associated with
biology so it’s a very modern nuanced
view fortunately there’s a next
generation of giant ground-based
telescopes to assist
in the hand for biosignatures in the
nearby universe and the one I’m most
excited about is European it’s called
the European extremely large telescope
very imaginative named as a 39 meter
mirror we joke that the next telescope
is called a humungous D large telescope
so so it’s a thirty nine meter mirror
and just look at a picture just check
out how small that truck is next to the
telescope this thing costs a billion
euros or will cost a billion euros is
almost complete so the the e-elt will
take exquisite spectra of molecules in
the atmospheres of exoplanets so this
example I’m showing is that of oxygen if
oxygen would exist in an axial planet
atmosphere this telescope would
definitively tell you that it’s there
and in fact you may have seen the news
very recently that we found iron and
titanium in a very hot exoplanet is
using exactly the same technique and in
fact the interpretation of such a
spectrum reduces to an image recognition
problem very similar to how you analyze
images in medicine which is why at the
University of Bern we are teaming up of
the medical scientists to develop
interpretational techniques based on
artificial intelligence this is ongoing
work the ones of you who think about
this problem may object and say that but
oxygen is not a very good bio signature
and and you would be right because we
now understand that they are a biotic
ways to make oxygen so without biology
and one way to do that is using the so
called photolysis of water meaning that
ultraviolet radiation from the light
hits the atmosphere of the exoplanet
breaks up the water molecules into
hydrogen and oxygen the hydrogen would
escape the oxygen would stay behind and
it looks like it came from life but it’s
not biology perhaps a better molecule is
methyl chloride on earth at least methyl
chloride is uniquely associated with
biology and given good enough data and a
spectrum that is covers enough colors or
wavelengths we could identify the
spectral fingerprint of methyl chloride
by the middle
dollar question or the billion dollar
question given that telescope is is
methyl chloride a robust bio signature
for all of the exoplanets we will find
out in the nearby universe and this is
an open question
looking ahead NASA is studying for
mission concepts for the next generation
of space telescope that will be launched
in the 2030s and 40s when I’m retired
one of them is called Louvois
and this is the first time in human
history that a space telescope is being
designed to detect mainly detect bio
signatures and we own the louvre our
team has many questions how big should
the mirror be so this cartoon shows you
the mirrors of the hubble space
telescope the James Webb Space Telescope
which I mentioned and the Louvre our
space telescope which has a mirror
between 9 and 15 meters which makes the
two point four meter mirror of Hubble
look very small if the solar system was
ten parsecs away roughly 30 light-years
this is the photograph that Louvois
would take of the solar system whose
Rockets should be used it always blows
my mind that during one of the telecoms
of the Louvre our team we were having a
very serious discussion about whether we
should use the next generation rocket of
NASA Elon Musk or Jeff Bezos it was a
serious discussion with plans at all how
are we gonna pay for it but I think the
most important question of all is how
common is life in the nearby universe
we believe that Louvois will conduct the
most definitive census of
extraterrestrial life in the nearby
universe and finally set us on the path
to answering the question are we truly
alone
here’s an aspirational picture taken by
the Voyager spacecraft it shows the
earth as a pale blue dot so you couldn’t
make out the continents and the oceans
and the clouds of Earth in
high-definition
by if you took a spectrum of this pale
blue dot and you studied the signatures
you could make out the presence of ozone
water methane and carbon dioxide and you
could possibly come to the conclusion
that there’s something interesting
happening on this planet I would like to
end by going back to Giordano Bruno
remember what you said she said there
countless suns and countless earth all
rotating around their Suns in exactly
the same way as our system our solar
system we now understand that Bruna was
right and here’s the modern take on what
Bruno said there are hundred billion
stars in our galaxy alone at least 10%
half exoplanets there are hundred
billion galaxies in the observable
universe there’s a mind-boggling number
of exoplanets so if we are truly alone
life must be very rare indeed or god is
playing a joke on us thank you for your
time [Applause]
by humanity is are we alone and the
modern version of this question that
astronomers are asking is how do we scan
the heavens to find out so in the next
18 minutes I want to bring bring you on
a grand tour of how modern Astra EXO
planet astronomers I’m sorry
attempting to address this very old
question you should take three things
away from my talk the first is that we
the exoplanet astronomers are the modern
descendants of Giordano Bruno whom I’ll
tell you about in a moment the second is
a paradox we seem to know much less
about nearby stars and their exoplanets
than those they are very far away and
the third is that for the first time in
human history we have a way of scanning
worlds very far away to tell you about
possible signs of life so my story or
our story starts with Giordano Bruno who
live in the 16th century
Giordano Giordano was a iconoclast
meaning that he really liked to piss
people off and he was eventually
executed for heresy but not before
making the following statement which is
there are countless suns and countless
earths all rotating around their Suns in
exactly the same way as the planets of
our system you need to appreciate that
this was a very radical statement at a
time in human history you could get into
a lot of trouble for saying this but
Enza he was right it turns out that if
you just stare stars in the sky by dumb
luck some of these stars will have
planets that pass in front of them that
cause a little tiny dip in the light
called a transit and this is the method
by which the Kepler space telescope has
discovered thousands of planets orbiting
other stars beyond our solar system
known as exoplanets here’s a way to
visualize these discoveries so I’m
showing you a chart in which I’m showing
the size of the exoplanet of Units
versus the orbital period in days and so
the earth on this chart would have a
size of 1
and a period of 365 days immediately you
see two surprises the first surprise is
that there seems to be a population of
exoplanets with roughly the size of our
Jupiter but orbiting with periods of a
few days and not twelve years
this means that their atmospheres are
really hard thousands of degrees hot but
my father the bigger surprise at least
to me is that there are exoplanets with
sizes between that of Neptune there is
no such planet in our solar system no
example of such a super earth and this
teaches you a very important lesson
which is that if you would like to
understand exoplanets in the nearby
universe you can’t just look in the
solar system you need to look beyond
here’s another surprise you may be
surprised to know that in our cosmic
neighborhood the Sun is actually not a
typical star a typical stars rather is
dimmer and is cooler in temperature and
they are usually called
red dwarfs not so far away is a red
dwarf called Trappist one and very
recently just in the last few months
astronomers including my colleagues at
been discovered seven of size or smaller
exoplanets orbiting the Trappist one
star in a very tight configuration in
fact the configuration is so tight that
you can fit the entire system within the
orbit of mercury in our solar system but
because trap is one is cooler than the
Sun is half the temperature is still
possible that even though they are so
close that some of these exoplanets
could have water on their rocky surfaces
and they’re really the only way to tell
is to study the atmospheres of these
planets so I just tell you that we have
discovered thousands of exoplanets but
the reality is that only a handful of
them are close enough for us to study
their atmospheres and here’s a way to
visualize that challenge I’m going to
show you a chart again of the size of
the exoplanet again in of units by now
I’m going to show you the distance away
in parsecs so a parsec is three
lightyears
light-year is the distance that light
travels in one year it’s a very vast
distance just just to give you a sense
of how fast this is it takes like one
second to go from here to the moon so a
light is a very large distance the first
thing you see is that the Kepler
discoveries in blue are very far away a
few hundred to a thousand parsecs much
too far for us to study their
atmospheres and tell you if their water
or carbon dioxide and so on there’s a
new NASA telescope called tests which
I’ll tell you about in a few minutes
that will discover exoplanets ten times
closer so we have a fighting chance of
studying their atmospheres but by but by
far the most interesting exoplanets are
the ones there are tens of parsecs away
and I just tell you about track this one
and the reason why trap is what is
interesting is because if you look at
the chart track this one has the planets
the seventh planet of Troubles one have
roughly the size of Earth that almost 10
parsecs away very close almost our
carbon our cosmic garden and the sizes
of these circles indicate how easy or
difficult it is to detect the transit so
large circle means easy to detect
transits so they have large circles
that’s good but they say that’s a
paradox in this graph which is why is
this region empty so the region between
us and ten parsecs is empty and it’s
surprising because the test statistics
tell us to expect thousands of
exoplanets and yet this region is nearly
empty why is that just think about it
right it’s a paradox because we know
less about about the exoplanet
population around nearby stars then we
know around faraway stars the paradox
comes about because of something called
the bright star paradox so if I was
using a telescope on earth to look at a
star with an exoplanet what I’m really
interested in is the tiny dip in light
that the transit causes but because I’m
observing through the atmosphere of
Earth which is turbulent the turbulence
typically creates a signal that’s
comparable to or larger than the signal
of the transit so to check my discovery
I have to point the telescope at a
so-called reference
a starter is roughly the same brightness
roughly the same type roughly the same
temperature and not too far away but the
problem is that bright stars are very
rare in the sky so it’s very rare almost
impossible to find a bright star a
bright reference star next to the bright
star you’re interested in and this is
the reason why we know almost nothing
about exoplanets around bright stars how
do you overcome this problem you
overcome this problem by placing your
telescopes in space above the Earth’s
atmosphere so that you don’t have to
worry about reference stars so in the
next few minutes I’m gonna tell you
about three space telescopes they have
either launched or will launch in the
next few years that will revolutionize
our understanding of exoplanets around
nearby stars the first telescope as I
promised is called the tests mission of
NASA tests just launched a few months
ago successfully on a falcon 9 rocket
it’s now in space taking data we will
see the results very soon and the
strategy of tests is to do an all-sky
survey so we will look at every patch of
sky but the price to pay for such white
coverage is that test will only look at
each patch for 27 days this means that
the exoplanets that test will find will
have our two periods of roughly a week
the next Space Telescope I will tell you
about is called ke ops this is our local
pride and joy is a space mission of the
European Space Agency or ISA is that by
Switzerland we are paying 30% of the
bill and in fact it’s lab at the
University of Bell and the strategy of k
ops is a little bit different it’s not
doing the all-sky survey the test is
doing rather K Ops is looking at golden
targets that we found to be interesting
in the past there are additional hints
of showing interesting exoplanets and we
would like to detect the really
interesting ones that we can follow up
to stay there amis fears together the
two space missions Tess and K ops would
deliver a treasure trove of the most
interesting exoplanets in the nearby
universe that we can then study their
atmospheres so I keep saying atmospheres
but how do you really study the
atmosphere
excellent you do it by you take the
light from an exoplanet and you split it
into different colors it’s called a
spectrum is analogous to taking the
fingerprint of a person so given good
enough data and if you spread the light
across enough colors you can distinguish
between say water and carbon dioxide in
this example I’m showing you and the
Space Telescope that would do this
really really well it’s the most
expensive one ever built by humanity
this is the James Webb Space Telescope
they were launched in 2021 so I’ve told
you how to detect exoplanets around
bright stars I’ve described to you how
to take their spectral fingerprints the
next logical step is how do we use these
techniques to tell if there’s life on an
exoplanet that’s the big question
right and the answer is that I would
like to identify a molecule that is not
only uniquely associated with life but
that can accumulate in large amounts in
the atmosphere and exist in the form of
a gas so I can detect it using a
telescope and I can look at in the
spectrum this is called a bio signature
unfortunately many of the gases produced
by life our soup reduced by rocks
geology so the methane produced by this
cow would be may as well come from the
ground I can’t really tell so the
challenge of bio signatures is how do I
detect signs of biology in the face of
geological false positives that’s the
challenge the traditional view of bio
signatures is that there’s a magic
molecule that will tell me once and for
all on all exoplanets in the universe
when I have life the modern view or bio
signatures is that there’s no such magic
molecule instead you have to detect a
family of molecules you have to assess
the environment from which these
molecules emerge the atmosphere then you
have we would have to assign a
probability as to where these fam this
family of molecules is associated with
biology so it’s a very modern nuanced
view fortunately there’s a next
generation of giant ground-based
telescopes to assist
in the hand for biosignatures in the
nearby universe and the one I’m most
excited about is European it’s called
the European extremely large telescope
very imaginative named as a 39 meter
mirror we joke that the next telescope
is called a humungous D large telescope
so so it’s a thirty nine meter mirror
and just look at a picture just check
out how small that truck is next to the
telescope this thing costs a billion
euros or will cost a billion euros is
almost complete so the the e-elt will
take exquisite spectra of molecules in
the atmospheres of exoplanets so this
example I’m showing is that of oxygen if
oxygen would exist in an axial planet
atmosphere this telescope would
definitively tell you that it’s there
and in fact you may have seen the news
very recently that we found iron and
titanium in a very hot exoplanet is
using exactly the same technique and in
fact the interpretation of such a
spectrum reduces to an image recognition
problem very similar to how you analyze
images in medicine which is why at the
University of Bern we are teaming up of
the medical scientists to develop
interpretational techniques based on
artificial intelligence this is ongoing
work the ones of you who think about
this problem may object and say that but
oxygen is not a very good bio signature
and and you would be right because we
now understand that they are a biotic
ways to make oxygen so without biology
and one way to do that is using the so
called photolysis of water meaning that
ultraviolet radiation from the light
hits the atmosphere of the exoplanet
breaks up the water molecules into
hydrogen and oxygen the hydrogen would
escape the oxygen would stay behind and
it looks like it came from life but it’s
not biology perhaps a better molecule is
methyl chloride on earth at least methyl
chloride is uniquely associated with
biology and given good enough data and a
spectrum that is covers enough colors or
wavelengths we could identify the
spectral fingerprint of methyl chloride
by the middle
dollar question or the billion dollar
question given that telescope is is
methyl chloride a robust bio signature
for all of the exoplanets we will find
out in the nearby universe and this is
an open question
looking ahead NASA is studying for
mission concepts for the next generation
of space telescope that will be launched
in the 2030s and 40s when I’m retired
one of them is called Louvois
and this is the first time in human
history that a space telescope is being
designed to detect mainly detect bio
signatures and we own the louvre our
team has many questions how big should
the mirror be so this cartoon shows you
the mirrors of the hubble space
telescope the James Webb Space Telescope
which I mentioned and the Louvre our
space telescope which has a mirror
between 9 and 15 meters which makes the
two point four meter mirror of Hubble
look very small if the solar system was
ten parsecs away roughly 30 light-years
this is the photograph that Louvois
would take of the solar system whose
Rockets should be used it always blows
my mind that during one of the telecoms
of the Louvre our team we were having a
very serious discussion about whether we
should use the next generation rocket of
NASA Elon Musk or Jeff Bezos it was a
serious discussion with plans at all how
are we gonna pay for it but I think the
most important question of all is how
common is life in the nearby universe
we believe that Louvois will conduct the
most definitive census of
extraterrestrial life in the nearby
universe and finally set us on the path
to answering the question are we truly
alone
here’s an aspirational picture taken by
the Voyager spacecraft it shows the
earth as a pale blue dot so you couldn’t
make out the continents and the oceans
and the clouds of Earth in
high-definition
by if you took a spectrum of this pale
blue dot and you studied the signatures
you could make out the presence of ozone
water methane and carbon dioxide and you
could possibly come to the conclusion
that there’s something interesting
happening on this planet I would like to
end by going back to Giordano Bruno
remember what you said she said there
countless suns and countless earth all
rotating around their Suns in exactly
the same way as our system our solar
system we now understand that Bruna was
right and here’s the modern take on what
Bruno said there are hundred billion
stars in our galaxy alone at least 10%
half exoplanets there are hundred
billion galaxies in the observable
universe there’s a mind-boggling number
of exoplanets so if we are truly alone
life must be very rare indeed or god is
playing a joke on us thank you for your
time [Applause]
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