you
you [Music]
so I’m a research astrophysicist at a
so I’m a research astrophysicist at a museum in the department founded by
museum in the department founded by
museum in the department founded by someone some of you may have heard of
someone some of you may have heard of
someone some of you may have heard of neil degrasse tyson and what I want to
neil degrasse tyson and what I want to
neil degrasse tyson and what I want to talk to you about today is the very
talk to you about today is the very
talk to you about today is the very interesting situation that we found
interesting situation that we found
interesting situation that we found ourselves in in learning about the
ourselves in in learning about the
ourselves in in learning about the universe because we are living in a time
universe because we are living in a time
universe because we are living in a time where we have understood that the
where we have understood that the
where we have understood that the universe is far stranger than we would
universe is far stranger than we would
universe is far stranger than we would have thought if we go back to medieval
have thought if we go back to medieval
have thought if we go back to medieval times in Europe the earth was thought
times in Europe the earth was thought
times in Europe the earth was thought not as being at the center of things but
not as being at the center of things but
not as being at the center of things but at the bottom of things it was where all
at the bottom of things it was where all
at the bottom of things it was where all the dreck and garbage and sin fell the
the dreck and garbage and sin fell the
the dreck and garbage and sin fell the heavens were pure the heavens were where
heavens were pure the heavens were where
heavens were pure the heavens were where God lived the earth not so much during
God lived the earth not so much during
God lived the earth not so much during the Enlightenment Copernicus and his
the Enlightenment Copernicus and his
the Enlightenment Copernicus and his peers said we’ll wait a moment things
peers said we’ll wait a moment things
peers said we’ll wait a moment things aren’t so bad maybe the earth isn’t
aren’t so bad maybe the earth isn’t
aren’t so bad maybe the earth isn’t actually all the way at the bottom maybe
actually all the way at the bottom maybe
actually all the way at the bottom maybe it’s somewhere in the middle and the Sun
it’s somewhere in the middle and the Sun
it’s somewhere in the middle and the Sun is at the bottom this was the principle
is at the bottom this was the principle
is at the bottom this was the principle of mediocrity which was far better than
of mediocrity which was far better than
of mediocrity which was far better than being at the very bottom of the scale
being at the very bottom of the scale
being at the very bottom of the scale well this was an interesting idea but
well this was an interesting idea but
well this was an interesting idea but when it was implemented mathematically
when it was implemented mathematically
when it was implemented mathematically it was bound that if he still assume
it was bound that if he still assume
it was bound that if he still assume that the heavens were pure and that
that the heavens were pure and that
that the heavens were pure and that heavenly bodies moved in perfect circles
heavenly bodies moved in perfect circles
heavenly bodies moved in perfect circles you hadn’t actually progressed very much
you hadn’t actually progressed very much
you hadn’t actually progressed very much from ptolemies ideas that you had
from ptolemies ideas that you had
from ptolemies ideas that you had circles and then epicyclic smaller
circles and then epicyclic smaller
circles and then epicyclic smaller circles that explained planetary motions
circles that explained planetary motions
circles that explained planetary motions now it turns out that ptolemies ideas
now it turns out that ptolemies ideas
now it turns out that ptolemies ideas lasted for so long partly because the
lasted for so long partly because the
lasted for so long partly because the system he set up was very very good it
system he set up was very very good it
system he set up was very very good it could explain the motions of the planets
could explain the motions of the planets
could explain the motions of the planets and make predictions that were extremely
and make predictions that were extremely
and make predictions that were extremely accurate he did this by making
accurate he did this by making
accurate he did this by making some special purpose adjustments not
some special purpose adjustments not
some special purpose adjustments not just the epicycles but every planet did
just the epicycles but every planet did
just the epicycles but every planet did not go around the earth it went around
not go around the earth it went around
not go around the earth it went around the equant which was a point of the
the equant which was a point of the
the equant which was a point of the earth that you had to assume to get the
earth that you had to assume to get the
earth that you had to assume to get the planets to behave properly so there were
planets to behave properly so there were
planets to behave properly so there were a lot of special-purpose fixes but it
a lot of special-purpose fixes but it
a lot of special-purpose fixes but it was a system that worked when Kepler guy
was a system that worked when Kepler guy
was a system that worked when Kepler guy up there drops the assumption of
up there drops the assumption of
up there drops the assumption of circular motion and assumes ellipses yes
circular motion and assumes ellipses yes
circular motion and assumes ellipses yes it’s a much simpler system but the
it’s a much simpler system but the
it’s a much simpler system but the difference in predictive power was a
difference in predictive power was a
difference in predictive power was a matter of eight seconds of arc in
matter of eight seconds of arc in
matter of eight seconds of arc in position of the planet Mars eight
position of the planet Mars eight
position of the planet Mars eight seconds of arc is the width of a coin 10
seconds of arc is the width of a coin 10
seconds of arc is the width of a coin 10 blocks away you needed huge naked eye
blocks away you needed huge naked eye
blocks away you needed huge naked eye instruments to even measure that you had
instruments to even measure that you had
instruments to even measure that you had to site along that extremely long arm
to site along that extremely long arm
to site along that extremely long arm and swing it back and forth to measure
and swing it back and forth to measure
and swing it back and forth to measure the angle at which you are observing
the angle at which you are observing
the angle at which you are observing something so already in the naked eye
something so already in the naked eye
something so already in the naked eye era we’re talking large instruments and
era we’re talking large instruments and
era we’re talking large instruments and great observational dedication to
great observational dedication to
great observational dedication to understand the fundamentals of our
understand the fundamentals of our
understand the fundamentals of our universe during the same period the
universe during the same period the
universe during the same period the first telescopes start to be built
first telescopes start to be built
first telescopes start to be built Galileo didn’t invent the telescope but
Galileo didn’t invent the telescope but
Galileo didn’t invent the telescope but he was an early adopter and he was
he was an early adopter and he was
he was an early adopter and he was aggressive in getting the word out that
aggressive in getting the word out that
aggressive in getting the word out that wait the heavens are not pure there are
wait the heavens are not pure there are
wait the heavens are not pure there are mountains there are craters there are
mountains there are craters there are
mountains there are craters there are imperfections on the moon this picture
imperfections on the moon this picture
imperfections on the moon this picture by the way was taken by Galileo the
by the way was taken by Galileo the
by the way was taken by Galileo the spacecraft on its way to Jupiter well
spacecraft on its way to Jupiter well
spacecraft on its way to Jupiter well now we had some understanding of the
now we had some understanding of the
now we had some understanding of the solar system that it was a heliocentric
solar system that it was a heliocentric
solar system that it was a heliocentric solar system with planets moving and
solar system with planets moving and
solar system with planets moving and imperfect ellipses to step out further
imperfect ellipses to step out further
imperfect ellipses to step out further we had to understand the distances to
we had to understand the distances to
we had to understand the distances to the stars and this took hundreds of
the stars and this took hundreds of
the stars and this took hundreds of years because the stars are very far
years because the stars are very far
years because the stars are very far away you can measure their distances
away you can measure their distances
away you can measure their distances with parallax but parallax right you
with parallax but parallax right you
with parallax but parallax right you hold out your finger and if it’s close
hold out your finger and if it’s close
hold out your finger and if it’s close to you and you go one eye to the other
to you and you go one eye to the other
to you and you go one eye to the other you’ll see it move a lot if you move it
you’ll see it move a lot if you move it
you’ll see it move a lot if you move it out further it doesn’t move as much well
out further it doesn’t move as much well
out further it doesn’t move as much well stars move fractions of a single arc
stars move fractions of a single arc
stars move fractions of a single arc second so you needed these very you
second so you needed these very you
second so you needed these very you needed substantial telescopes in order
needed substantial telescopes in order
needed substantial telescopes in order to make that measurement and understand
to make that measurement and understand
to make that measurement and understand that the stars were trillions of miles
that the stars were trillions of miles
that the stars were trillions of miles away parallax only gets you so far if
away parallax only gets you so far if
away parallax only gets you so far if you don’t have a telescope in space
you don’t have a telescope in space
you don’t have a telescope in space that’s outside the Earth’s atmosphere
that’s outside the Earth’s atmosphere
that’s outside the Earth’s atmosphere and the next step was one of the first
and the next step was one of the first
and the next step was one of the first instances of the application of what we
instances of the application of what we
instances of the application of what we now call Big Data now at the turn of the
now call Big Data now at the turn of the
now call Big Data now at the turn of the last century around 1900 a computer was
last century around 1900 a computer was
last century around 1900 a computer was not a machine it was a profession these
not a machine it was a profession these
not a machine it was a profession these were computers at the Harvard College
were computers at the Harvard College
were computers at the Harvard College observatory they were the people who
observatory they were the people who
observatory they were the people who were in touch with the data who are
were in touch with the data who are
were in touch with the data who are actually working with it and they made
actually working with it and they made
actually working with it and they made some very important discoveries one of
some very important discoveries one of
some very important discoveries one of them Henrietta Leavitt in the center
them Henrietta Leavitt in the center
them Henrietta Leavitt in the center here was the person who realized that
here was the person who realized that
here was the person who realized that the variability period of a certain kind
the variability period of a certain kind
the variability period of a certain kind of star called a Cepheid correlated
of star called a Cepheid correlated
of star called a Cepheid correlated directly with its brightness as shown in
directly with its brightness as shown in
directly with its brightness as shown in that graph up there the brightness going
that graph up there the brightness going
that graph up there the brightness going up the period going to the right so if
up the period going to the right so if
up the period going to the right so if you could walk something varying you
you could walk something varying you
you could walk something varying you knew how bright it actually was by
knew how bright it actually was by
knew how bright it actually was by measuring how dim it appeared you can
measuring how dim it appeared you can
measuring how dim it appeared you can see its distance that allowed us to
see its distance that allowed us to
see its distance that allowed us to measure the distance across our own
measure the distance across our own
measure the distance across our own galaxy
galaxy
galaxy and even more importantly to other
and even more importantly to other
and even more importantly to other galaxies and to understand that other
galaxies and to understand that other
galaxies and to understand that other galaxies were objects like our own Milky
galaxies were objects like our own Milky
galaxies were objects like our own Milky Way galaxy but outside of our own now if
Way galaxy but outside of our own now if
Way galaxy but outside of our own now if the universe is a static and unchanging
the universe is a static and unchanging
the universe is a static and unchanging universe as we perceive it on the human
universe as we perceive it on the human
universe as we perceive it on the human scale then those other galaxies like our
scale then those other galaxies like our
scale then those other galaxies like our own ought to move like this here we are
own ought to move like this here we are
own ought to move like this here we are at the center of the image the galaxies
at the center of the image the galaxies
at the center of the image the galaxies that are moving towards us their light
that are moving towards us their light
that are moving towards us their light gets squeezed a little and moved to the
gets squeezed a little and moved to the
gets squeezed a little and moved to the blue the galaxies that are moving away
blue the galaxies that are moving away
blue the galaxies that are moving away from us the light gets stretched and
from us the light gets stretched and
from us the light gets stretched and moved to the red it’s called blue shift
moved to the red it’s called blue shift
moved to the red it’s called blue shift or red shift it’s the principle on which
or red shift it’s the principle on which
or red shift it’s the principle on which the radar gun works if the cop points
the radar gun works if the cop points
the radar gun works if the cop points the radar gun at your car and the
the radar gun at your car and the
the radar gun at your car and the returning waves are shifted too far to
returning waves are shifted too far to
returning waves are shifted too far to the blue you get a ticket galaxies
the blue you get a ticket galaxies
the blue you get a ticket galaxies should have been moving randomly when
should have been moving randomly when
should have been moving randomly when measurements were taken of distant
measurements were taken of distant
measurements were taken of distant galaxies this was not the result this
galaxies this was not the result this
galaxies this was not the result this was so the guy up here that’s the Slifer
was so the guy up here that’s the Slifer
was so the guy up here that’s the Slifer finds that practically every galaxy is
finds that practically every galaxy is
finds that practically every galaxy is moving away from us is redshifted only a
moving away from us is redshifted only a
moving away from us is redshifted only a few nearby galaxies are moving towards
few nearby galaxies are moving towards
few nearby galaxies are moving towards us okay I’m going to show you a clip
us okay I’m going to show you a clip
us okay I’m going to show you a clip from a space show that we did at the
from a space show that we did at the
from a space show that we did at the Museum called dark universe and this is
Museum called dark universe and this is
Museum called dark universe and this is our galaxy as we pull out we will see an
our galaxy as we pull out we will see an
our galaxy as we pull out we will see an accurate map of all the
accurate map of all the
accurate map of all the three-dimensional positions of galaxies
three-dimensional positions of galaxies
three-dimensional positions of galaxies that we have measured and their
that we have measured and their
that we have measured and their velocities there’s the Andromeda galaxy
velocities there’s the Andromeda galaxy
velocities there’s the Andromeda galaxy Hubble was the first person to find a
Hubble was the first person to find a
Hubble was the first person to find a Cepheid variable in the Andromeda galaxy
Cepheid variable in the Andromeda galaxy
Cepheid variable in the Andromeda galaxy and show that this was not just a fuzzy
and show that this was not just a fuzzy
and show that this was not just a fuzzy nebula like they get nebulae in our own
nebula like they get nebulae in our own
nebula like they get nebulae in our own galaxies around star forming regions but
galaxies around star forming regions but
galaxies around star forming regions but was a different object and here we are
was a different object and here we are
was a different object and here we are in the universe of galaxies they have
in the universe of galaxies they have
in the universe of galaxies they have structure and that structure
structure and that structure
structure and that structure we’ll talk about later but these
we’ll talk about later but these
we’ll talk about later but these galaxies are all expanding away now if
galaxies are all expanding away now if
galaxies are all expanding away now if all the galaxies are expanding away from
all the galaxies are expanding away from
all the galaxies are expanding away from you there are two possibilities either
you there are two possibilities either
you there are two possibilities either you are a very lucky person and you are
you are a very lucky person and you are
you are a very lucky person and you are sitting right at the center of the
sitting right at the center of the
sitting right at the center of the universe which some people believe or
universe which some people believe or
universe which some people believe or it’s not just us everybody sees
it’s not just us everybody sees
it’s not just us everybody sees expansion so this galaxy sees expansion
expansion so this galaxy sees expansion
expansion so this galaxy sees expansion but so does another galaxy and if that
but so does another galaxy and if that
but so does another galaxy and if that is true then the entire universe must be
is true then the entire universe must be
is true then the entire universe must be expanding its not just expanding out
expanding its not just expanding out
expanding its not just expanding out into something everywhere is expanding
into something everywhere is expanding
into something everywhere is expanding every point in the universe is expanding
every point in the universe is expanding
every point in the universe is expanding away from every other point objects that
away from every other point objects that
away from every other point objects that are bound together by chemical forces or
are bound together by chemical forces or
are bound together by chemical forces or gravitational forces space expands out
gravitational forces space expands out
gravitational forces space expands out from under them that’s why we’re not
from under them that’s why we’re not
from under them that’s why we’re not expanded happily but if every object is
expanded happily but if every object is
expanded happily but if every object is expanding from every other object then
expanding from every other object then
expanding from every other object then if you project backwards in time things
if you project backwards in time things
if you project backwards in time things must have been once much much denser and
must have been once much much denser and
must have been once much much denser and therefore much much hotter and that is
therefore much much hotter and that is
therefore much much hotter and that is the fundamental reason for believing in
the fundamental reason for believing in
the fundamental reason for believing in the idea of a big bang that once the
the idea of a big bang that once the
the idea of a big bang that once the universe was extraordinarily hot and
universe was extraordinarily hot and
universe was extraordinarily hot and dense in fact once the universe was as
dense in fact once the universe was as
dense in fact once the universe was as hot and dense as the surface of the Sun
hot and dense as the surface of the Sun
hot and dense as the surface of the Sun and the light emitted at that time which
and the light emitted at that time which
and the light emitted at that time which is what’s visible light at the time has
is what’s visible light at the time has
is what’s visible light at the time has been traveling through the universe and
been traveling through the universe and
been traveling through the universe and getting stretched out as it travels so
getting stretched out as it travels so
getting stretched out as it travels so that it is now shifted from the visible
that it is now shifted from the visible
that it is now shifted from the visible light to the infrared light to the
light to the infrared light to the
light to the infrared light to the microwave and this
microwave and this
microwave and this the Cosmic Microwave Background the very
the Cosmic Microwave Background the very
the Cosmic Microwave Background the very small variations in which were measured
small variations in which were measured
small variations in which were measured in this map by the Ponk satellite and
in this map by the Ponk satellite and
in this map by the Ponk satellite and have been measured over the years okay
have been measured over the years okay
have been measured over the years okay so we have a universe that’s expanding
so we have a universe that’s expanding
so we have a universe that’s expanding from an origin when this was first
from an origin when this was first
from an origin when this was first proposed it was denounced as creationist
proposed it was denounced as creationist
proposed it was denounced as creationist and indeed it was proposed by a Catholic
and indeed it was proposed by a Catholic
and indeed it was proposed by a Catholic priest Father lometa and yet all the
priest Father lometa and yet all the
priest Father lometa and yet all the evidence that we have points to the idea
evidence that we have points to the idea
evidence that we have points to the idea that the universe Kate started at a
that the universe Kate started at a
that the universe Kate started at a definite time extraordinarily hot
definite time extraordinarily hot
definite time extraordinarily hot extraordinarily dense furthermore
extraordinarily dense furthermore
extraordinarily dense furthermore furthermore most of the matter in the
furthermore most of the matter in the
furthermore most of the matter in the universe is not the stuff we are made of
universe is not the stuff we are made of
universe is not the stuff we are made of it’s not Adams of any sort the first
it’s not Adams of any sort the first
it’s not Adams of any sort the first person who realized this was this guy up
person who realized this was this guy up
person who realized this was this guy up here fritz zwicky back in the 1930s he
here fritz zwicky back in the 1930s he
here fritz zwicky back in the 1930s he looked at galaxy clusters and realized
looked at galaxy clusters and realized
looked at galaxy clusters and realized that there was far too much mass in them
that there was far too much mass in them
that there was far too much mass in them they couldn’t be explained by the
they couldn’t be explained by the
they couldn’t be explained by the visible galaxies he measured how fast
visible galaxies he measured how fast
visible galaxies he measured how fast galaxies were orbiting using their red
galaxies were orbiting using their red
galaxies were orbiting using their red shifts and compared to how much mass was
shifts and compared to how much mass was
shifts and compared to how much mass was in the stars whose brightness he could
in the stars whose brightness he could
in the stars whose brightness he could measure and the answer came out it was a
measure and the answer came out it was a
measure and the answer came out it was a hundred times wrong there was a hundred
hundred times wrong there was a hundred
hundred times wrong there was a hundred times more mass in that cluster than
times more mass in that cluster than
times more mass in that cluster than could be accounted for by the visible
could be accounted for by the visible
could be accounted for by the visible galaxies well back then first of all he
galaxies well back then first of all he
galaxies well back then first of all he was a famously follow mouth and paranoid
was a famously follow mouth and paranoid
was a famously follow mouth and paranoid guy who nobody liked and second we
guy who nobody liked and second we
guy who nobody liked and second we didn’t really understand galaxy clusters
didn’t really understand galaxy clusters
didn’t really understand galaxy clusters so everybody just sort of shoved it to
so everybody just sort of shoved it to
so everybody just sort of shoved it to the side until the 1970s when Vera Rubin
the side until the 1970s when Vera Rubin
the side until the 1970s when Vera Rubin comes along and looks at individual
comes along and looks at individual
comes along and looks at individual galaxies and how stars orbit around the
galaxies and how stars orbit around the
galaxies and how stars orbit around the center in those galaxies and she finds
center in those galaxies and she finds
center in those galaxies and she finds that if the stars were in the galaxy
that if the stars were in the galaxy
that if the stars were in the galaxy they should if the stars were the only
they should if the stars were the only
they should if the stars were the only mass in the galaxy they should orbit
mass in the galaxy they should orbit
mass in the galaxy they should orbit like this line labeled disk and yet they
like this line labeled disk and yet they
like this line labeled disk and yet they don’t they orbit like the top line
don’t they orbit like the top line
don’t they orbit like the top line meaning there’s lots of extra
meaning there’s lots of extra
meaning there’s lots of extra ass after that point people started
ass after that point people started
ass after that point people started taking the idea of dark matter seriously
taking the idea of dark matter seriously
taking the idea of dark matter seriously given the timing we’re going to keep
given the timing we’re going to keep
given the timing we’re going to keep going because that was bad enough but
going because that was bad enough but
going because that was bad enough but still we understood that now we know
still we understood that now we know
still we understood that now we know where most where all the mass is and
where most where all the mass is and
where most where all the mass is and mass will act on the expansion of the
mass will act on the expansion of the
mass will act on the expansion of the universe to slow it down because gravity
universe to slow it down because gravity
universe to slow it down because gravity is pulling it in now to measure the mass
is pulling it in now to measure the mass
is pulling it in now to measure the mass well it would be good to know how
well it would be good to know how
well it would be good to know how quickly the universe is decelerating how
quickly the universe is decelerating how
quickly the universe is decelerating how quickly that expansion is slowing down
quickly that expansion is slowing down
quickly that expansion is slowing down because of all the mass in the universe
because of all the mass in the universe
because of all the mass in the universe and so a number of teams in the 1990s
and so a number of teams in the 1990s
and so a number of teams in the 1990s set out to measure the deceleration of
set out to measure the deceleration of
set out to measure the deceleration of the universe by measuring galaxies at
the universe by measuring galaxies at
the universe by measuring galaxies at great distances and finding their red
great distances and finding their red
great distances and finding their red shifts they used a certain type of
shifts they used a certain type of
shifts they used a certain type of supernova it could be calibrated to
supernova it could be calibrated to
supernova it could be calibrated to reveal its absolute luminosity how
reveal its absolute luminosity how
reveal its absolute luminosity how bright it actually was and compare it to
bright it actually was and compare it to
bright it actually was and compare it to its apparent luminosity and they went
its apparent luminosity and they went
its apparent luminosity and they went out and found lots of supernovae with
out and found lots of supernovae with
out and found lots of supernovae with great effort and built robotic
great effort and built robotic
great effort and built robotic telescopes to do this and at the end it
telescopes to do this and at the end it
telescopes to do this and at the end it came down to this guy over on the Left
came down to this guy over on the Left
came down to this guy over on the Left who was a graduate student in the group
who was a graduate student in the group
who was a graduate student in the group taking all the data putting it together
taking all the data putting it together
taking all the data putting it together to measure the deceleration of the
to measure the deceleration of the
to measure the deceleration of the universe and so late one night he
universe and so late one night he
universe and so late one night he finishes the program and adds up all the
finishes the program and adds up all the
finishes the program and adds up all the numbers and gets out the answer and he’s
numbers and gets out the answer and he’s
numbers and gets out the answer and he’s got a sign error the deceleration is
got a sign error the deceleration is
got a sign error the deceleration is negative it’s not a deceleration at all
negative it’s not a deceleration at all
negative it’s not a deceleration at all it’s an acceleration well he goes back
it’s an acceleration well he goes back
it’s an acceleration well he goes back and gets his boss and his boss’s boss
and gets his boss and his boss’s boss
and gets his boss and his boss’s boss and they all check the numbers and it
and they all check the numbers and it
and they all check the numbers and it remains an acceleration it turns out
remains an acceleration it turns out
remains an acceleration it turns out that there’s something else besides
that there’s something else besides
that there’s something else besides matter and it is dominating the dynamics
matter and it is dominating the dynamics
matter and it is dominating the dynamics of our universe we’ve given it a label
of our universe we’ve given it a label
of our universe we’ve given it a label we’ve called it dark energy its energy
we’ve called it dark energy its energy
we’ve called it dark energy its energy that we cannot detect so it’s dark we
that we cannot detect so it’s dark we
that we cannot detect so it’s dark we know that to about ten percent it hasn’t
know that to about ten percent it hasn’t
know that to about ten percent it hasn’t changed over time there’s not more and
changed over time there’s not more and
changed over time there’s not more and more of it but yet it is causing our
more of it but yet it is causing our
more of it but yet it is causing our universe to go faster and faster so we
universe to go faster and faster so we
universe to go faster and faster so we are starting to characterize it more and
are starting to characterize it more and
are starting to characterize it more and more accurately but we still don’t know
more accurately but we still don’t know
more accurately but we still don’t know physically why it’s there why it is as
physically why it’s there why it is as
physically why it’s there why it is as strong as it is now we’ve now
strong as it is now we’ve now
strong as it is now we’ve now accomplished multiple independent
accomplished multiple independent
accomplished multiple independent measurements of how much dark matter
measurements of how much dark matter
measurements of how much dark matter there is and how much matter there is
there is and how much matter there is
there is and how much matter there is and this is Cosmic Microwave Background
and this is Cosmic Microwave Background
and this is Cosmic Microwave Background this is the supernova the other one is
this is the supernova the other one is
this is the supernova the other one is measuring the positions of galaxies and
measuring the positions of galaxies and
measuring the positions of galaxies and how fast they’re falling together they
how fast they’re falling together they
how fast they’re falling together they come together in that very small error
come together in that very small error
come together in that very small error circle and that small error circle is a
circle and that small error circle is a
circle and that small error circle is a place that is extraordinarily odd it is
place that is extraordinarily odd it is
place that is extraordinarily odd it is a universe dominated by dark energy and
a universe dominated by dark energy and
a universe dominated by dark energy and dark matter everything that we know
dark matter everything that we know
dark matter everything that we know about and can detect at this point is in
about and can detect at this point is in
about and can detect at this point is in that little 4% sliver of which only this
that little 4% sliver of which only this
that little 4% sliver of which only this little red sliver over here is the heavy
little red sliver over here is the heavy
little red sliver over here is the heavy elements the carb in the nitrogen the
elements the carb in the nitrogen the
elements the carb in the nitrogen the oxygen all the stuff that makes up us
oxygen all the stuff that makes up us
oxygen all the stuff that makes up us our planets aside from hydrogen most of
our planets aside from hydrogen most of
our planets aside from hydrogen most of the universe has not yet been detected
the universe has not yet been detected
the universe has not yet been detected Dark Matter is perhaps on the cusp of
Dark Matter is perhaps on the cusp of
Dark Matter is perhaps on the cusp of being detected there are many efforts
being detected there are many efforts
being detected there are many efforts being made to directly detect a dark
being made to directly detect a dark
being made to directly detect a dark matter particle they may be successful
matter particle they may be successful
matter particle they may be successful possibly soon dark energy we’re still in
possibly soon dark energy we’re still in
possibly soon dark energy we’re still in the in the mode of I’m a blind person
the in the mode of I’m a blind person
the in the mode of I’m a blind person and I’m feeling the elephant is it have
and I’m feeling the elephant is it have
and I’m feeling the elephant is it have a long skinny bit is it a big hard bit
a long skinny bit is it a big hard bit
a long skinny bit is it a big hard bit what is it that’s how we’re living in
what is it that’s how we’re living in
what is it that’s how we’re living in the question of understanding
the question of understanding
the question of understanding our own universe thank you
our own universe thank you
our own universe thank you [Applause]
you [Music]
so I’m a research astrophysicist at a
so I’m a research astrophysicist at a museum in the department founded by
museum in the department founded by
museum in the department founded by someone some of you may have heard of
someone some of you may have heard of
someone some of you may have heard of neil degrasse tyson and what I want to
neil degrasse tyson and what I want to
neil degrasse tyson and what I want to talk to you about today is the very
talk to you about today is the very
talk to you about today is the very interesting situation that we found
interesting situation that we found
interesting situation that we found ourselves in in learning about the
ourselves in in learning about the
ourselves in in learning about the universe because we are living in a time
universe because we are living in a time
universe because we are living in a time where we have understood that the
where we have understood that the
where we have understood that the universe is far stranger than we would
universe is far stranger than we would
universe is far stranger than we would have thought if we go back to medieval
have thought if we go back to medieval
have thought if we go back to medieval times in Europe the earth was thought
times in Europe the earth was thought
times in Europe the earth was thought not as being at the center of things but
not as being at the center of things but
not as being at the center of things but at the bottom of things it was where all
at the bottom of things it was where all
at the bottom of things it was where all the dreck and garbage and sin fell the
the dreck and garbage and sin fell the
the dreck and garbage and sin fell the heavens were pure the heavens were where
heavens were pure the heavens were where
heavens were pure the heavens were where God lived the earth not so much during
God lived the earth not so much during
God lived the earth not so much during the Enlightenment Copernicus and his
the Enlightenment Copernicus and his
the Enlightenment Copernicus and his peers said we’ll wait a moment things
peers said we’ll wait a moment things
peers said we’ll wait a moment things aren’t so bad maybe the earth isn’t
aren’t so bad maybe the earth isn’t
aren’t so bad maybe the earth isn’t actually all the way at the bottom maybe
actually all the way at the bottom maybe
actually all the way at the bottom maybe it’s somewhere in the middle and the Sun
it’s somewhere in the middle and the Sun
it’s somewhere in the middle and the Sun is at the bottom this was the principle
is at the bottom this was the principle
is at the bottom this was the principle of mediocrity which was far better than
of mediocrity which was far better than
of mediocrity which was far better than being at the very bottom of the scale
being at the very bottom of the scale
being at the very bottom of the scale well this was an interesting idea but
well this was an interesting idea but
well this was an interesting idea but when it was implemented mathematically
when it was implemented mathematically
when it was implemented mathematically it was bound that if he still assume
it was bound that if he still assume
it was bound that if he still assume that the heavens were pure and that
that the heavens were pure and that
that the heavens were pure and that heavenly bodies moved in perfect circles
heavenly bodies moved in perfect circles
heavenly bodies moved in perfect circles you hadn’t actually progressed very much
you hadn’t actually progressed very much
you hadn’t actually progressed very much from ptolemies ideas that you had
from ptolemies ideas that you had
from ptolemies ideas that you had circles and then epicyclic smaller
circles and then epicyclic smaller
circles and then epicyclic smaller circles that explained planetary motions
circles that explained planetary motions
circles that explained planetary motions now it turns out that ptolemies ideas
now it turns out that ptolemies ideas
now it turns out that ptolemies ideas lasted for so long partly because the
lasted for so long partly because the
lasted for so long partly because the system he set up was very very good it
system he set up was very very good it
system he set up was very very good it could explain the motions of the planets
could explain the motions of the planets
could explain the motions of the planets and make predictions that were extremely
and make predictions that were extremely
and make predictions that were extremely accurate he did this by making
accurate he did this by making
accurate he did this by making some special purpose adjustments not
some special purpose adjustments not
some special purpose adjustments not just the epicycles but every planet did
just the epicycles but every planet did
just the epicycles but every planet did not go around the earth it went around
not go around the earth it went around
not go around the earth it went around the equant which was a point of the
the equant which was a point of the
the equant which was a point of the earth that you had to assume to get the
earth that you had to assume to get the
earth that you had to assume to get the planets to behave properly so there were
planets to behave properly so there were
planets to behave properly so there were a lot of special-purpose fixes but it
a lot of special-purpose fixes but it
a lot of special-purpose fixes but it was a system that worked when Kepler guy
was a system that worked when Kepler guy
was a system that worked when Kepler guy up there drops the assumption of
up there drops the assumption of
up there drops the assumption of circular motion and assumes ellipses yes
circular motion and assumes ellipses yes
circular motion and assumes ellipses yes it’s a much simpler system but the
it’s a much simpler system but the
it’s a much simpler system but the difference in predictive power was a
difference in predictive power was a
difference in predictive power was a matter of eight seconds of arc in
matter of eight seconds of arc in
matter of eight seconds of arc in position of the planet Mars eight
position of the planet Mars eight
position of the planet Mars eight seconds of arc is the width of a coin 10
seconds of arc is the width of a coin 10
seconds of arc is the width of a coin 10 blocks away you needed huge naked eye
blocks away you needed huge naked eye
blocks away you needed huge naked eye instruments to even measure that you had
instruments to even measure that you had
instruments to even measure that you had to site along that extremely long arm
to site along that extremely long arm
to site along that extremely long arm and swing it back and forth to measure
and swing it back and forth to measure
and swing it back and forth to measure the angle at which you are observing
the angle at which you are observing
the angle at which you are observing something so already in the naked eye
something so already in the naked eye
something so already in the naked eye era we’re talking large instruments and
era we’re talking large instruments and
era we’re talking large instruments and great observational dedication to
great observational dedication to
great observational dedication to understand the fundamentals of our
understand the fundamentals of our
understand the fundamentals of our universe during the same period the
universe during the same period the
universe during the same period the first telescopes start to be built
first telescopes start to be built
first telescopes start to be built Galileo didn’t invent the telescope but
Galileo didn’t invent the telescope but
Galileo didn’t invent the telescope but he was an early adopter and he was
he was an early adopter and he was
he was an early adopter and he was aggressive in getting the word out that
aggressive in getting the word out that
aggressive in getting the word out that wait the heavens are not pure there are
wait the heavens are not pure there are
wait the heavens are not pure there are mountains there are craters there are
mountains there are craters there are
mountains there are craters there are imperfections on the moon this picture
imperfections on the moon this picture
imperfections on the moon this picture by the way was taken by Galileo the
by the way was taken by Galileo the
by the way was taken by Galileo the spacecraft on its way to Jupiter well
spacecraft on its way to Jupiter well
spacecraft on its way to Jupiter well now we had some understanding of the
now we had some understanding of the
now we had some understanding of the solar system that it was a heliocentric
solar system that it was a heliocentric
solar system that it was a heliocentric solar system with planets moving and
solar system with planets moving and
solar system with planets moving and imperfect ellipses to step out further
imperfect ellipses to step out further
imperfect ellipses to step out further we had to understand the distances to
we had to understand the distances to
we had to understand the distances to the stars and this took hundreds of
the stars and this took hundreds of
the stars and this took hundreds of years because the stars are very far
years because the stars are very far
years because the stars are very far away you can measure their distances
away you can measure their distances
away you can measure their distances with parallax but parallax right you
with parallax but parallax right you
with parallax but parallax right you hold out your finger and if it’s close
hold out your finger and if it’s close
hold out your finger and if it’s close to you and you go one eye to the other
to you and you go one eye to the other
to you and you go one eye to the other you’ll see it move a lot if you move it
you’ll see it move a lot if you move it
you’ll see it move a lot if you move it out further it doesn’t move as much well
out further it doesn’t move as much well
out further it doesn’t move as much well stars move fractions of a single arc
stars move fractions of a single arc
stars move fractions of a single arc second so you needed these very you
second so you needed these very you
second so you needed these very you needed substantial telescopes in order
needed substantial telescopes in order
needed substantial telescopes in order to make that measurement and understand
to make that measurement and understand
to make that measurement and understand that the stars were trillions of miles
that the stars were trillions of miles
that the stars were trillions of miles away parallax only gets you so far if
away parallax only gets you so far if
away parallax only gets you so far if you don’t have a telescope in space
you don’t have a telescope in space
you don’t have a telescope in space that’s outside the Earth’s atmosphere
that’s outside the Earth’s atmosphere
that’s outside the Earth’s atmosphere and the next step was one of the first
and the next step was one of the first
and the next step was one of the first instances of the application of what we
instances of the application of what we
instances of the application of what we now call Big Data now at the turn of the
now call Big Data now at the turn of the
now call Big Data now at the turn of the last century around 1900 a computer was
last century around 1900 a computer was
last century around 1900 a computer was not a machine it was a profession these
not a machine it was a profession these
not a machine it was a profession these were computers at the Harvard College
were computers at the Harvard College
were computers at the Harvard College observatory they were the people who
observatory they were the people who
observatory they were the people who were in touch with the data who are
were in touch with the data who are
were in touch with the data who are actually working with it and they made
actually working with it and they made
actually working with it and they made some very important discoveries one of
some very important discoveries one of
some very important discoveries one of them Henrietta Leavitt in the center
them Henrietta Leavitt in the center
them Henrietta Leavitt in the center here was the person who realized that
here was the person who realized that
here was the person who realized that the variability period of a certain kind
the variability period of a certain kind
the variability period of a certain kind of star called a Cepheid correlated
of star called a Cepheid correlated
of star called a Cepheid correlated directly with its brightness as shown in
directly with its brightness as shown in
directly with its brightness as shown in that graph up there the brightness going
that graph up there the brightness going
that graph up there the brightness going up the period going to the right so if
up the period going to the right so if
up the period going to the right so if you could walk something varying you
you could walk something varying you
you could walk something varying you knew how bright it actually was by
knew how bright it actually was by
knew how bright it actually was by measuring how dim it appeared you can
measuring how dim it appeared you can
measuring how dim it appeared you can see its distance that allowed us to
see its distance that allowed us to
see its distance that allowed us to measure the distance across our own
measure the distance across our own
measure the distance across our own galaxy
galaxy
galaxy and even more importantly to other
and even more importantly to other
and even more importantly to other galaxies and to understand that other
galaxies and to understand that other
galaxies and to understand that other galaxies were objects like our own Milky
galaxies were objects like our own Milky
galaxies were objects like our own Milky Way galaxy but outside of our own now if
Way galaxy but outside of our own now if
Way galaxy but outside of our own now if the universe is a static and unchanging
the universe is a static and unchanging
the universe is a static and unchanging universe as we perceive it on the human
universe as we perceive it on the human
universe as we perceive it on the human scale then those other galaxies like our
scale then those other galaxies like our
scale then those other galaxies like our own ought to move like this here we are
own ought to move like this here we are
own ought to move like this here we are at the center of the image the galaxies
at the center of the image the galaxies
at the center of the image the galaxies that are moving towards us their light
that are moving towards us their light
that are moving towards us their light gets squeezed a little and moved to the
gets squeezed a little and moved to the
gets squeezed a little and moved to the blue the galaxies that are moving away
blue the galaxies that are moving away
blue the galaxies that are moving away from us the light gets stretched and
from us the light gets stretched and
from us the light gets stretched and moved to the red it’s called blue shift
moved to the red it’s called blue shift
moved to the red it’s called blue shift or red shift it’s the principle on which
or red shift it’s the principle on which
or red shift it’s the principle on which the radar gun works if the cop points
the radar gun works if the cop points
the radar gun works if the cop points the radar gun at your car and the
the radar gun at your car and the
the radar gun at your car and the returning waves are shifted too far to
returning waves are shifted too far to
returning waves are shifted too far to the blue you get a ticket galaxies
the blue you get a ticket galaxies
the blue you get a ticket galaxies should have been moving randomly when
should have been moving randomly when
should have been moving randomly when measurements were taken of distant
measurements were taken of distant
measurements were taken of distant galaxies this was not the result this
galaxies this was not the result this
galaxies this was not the result this was so the guy up here that’s the Slifer
was so the guy up here that’s the Slifer
was so the guy up here that’s the Slifer finds that practically every galaxy is
finds that practically every galaxy is
finds that practically every galaxy is moving away from us is redshifted only a
moving away from us is redshifted only a
moving away from us is redshifted only a few nearby galaxies are moving towards
few nearby galaxies are moving towards
few nearby galaxies are moving towards us okay I’m going to show you a clip
us okay I’m going to show you a clip
us okay I’m going to show you a clip from a space show that we did at the
from a space show that we did at the
from a space show that we did at the Museum called dark universe and this is
Museum called dark universe and this is
Museum called dark universe and this is our galaxy as we pull out we will see an
our galaxy as we pull out we will see an
our galaxy as we pull out we will see an accurate map of all the
accurate map of all the
accurate map of all the three-dimensional positions of galaxies
three-dimensional positions of galaxies
three-dimensional positions of galaxies that we have measured and their
that we have measured and their
that we have measured and their velocities there’s the Andromeda galaxy
velocities there’s the Andromeda galaxy
velocities there’s the Andromeda galaxy Hubble was the first person to find a
Hubble was the first person to find a
Hubble was the first person to find a Cepheid variable in the Andromeda galaxy
Cepheid variable in the Andromeda galaxy
Cepheid variable in the Andromeda galaxy and show that this was not just a fuzzy
and show that this was not just a fuzzy
and show that this was not just a fuzzy nebula like they get nebulae in our own
nebula like they get nebulae in our own
nebula like they get nebulae in our own galaxies around star forming regions but
galaxies around star forming regions but
galaxies around star forming regions but was a different object and here we are
was a different object and here we are
was a different object and here we are in the universe of galaxies they have
in the universe of galaxies they have
in the universe of galaxies they have structure and that structure
structure and that structure
structure and that structure we’ll talk about later but these
we’ll talk about later but these
we’ll talk about later but these galaxies are all expanding away now if
galaxies are all expanding away now if
galaxies are all expanding away now if all the galaxies are expanding away from
all the galaxies are expanding away from
all the galaxies are expanding away from you there are two possibilities either
you there are two possibilities either
you there are two possibilities either you are a very lucky person and you are
you are a very lucky person and you are
you are a very lucky person and you are sitting right at the center of the
sitting right at the center of the
sitting right at the center of the universe which some people believe or
universe which some people believe or
universe which some people believe or it’s not just us everybody sees
it’s not just us everybody sees
it’s not just us everybody sees expansion so this galaxy sees expansion
expansion so this galaxy sees expansion
expansion so this galaxy sees expansion but so does another galaxy and if that
but so does another galaxy and if that
but so does another galaxy and if that is true then the entire universe must be
is true then the entire universe must be
is true then the entire universe must be expanding its not just expanding out
expanding its not just expanding out
expanding its not just expanding out into something everywhere is expanding
into something everywhere is expanding
into something everywhere is expanding every point in the universe is expanding
every point in the universe is expanding
every point in the universe is expanding away from every other point objects that
away from every other point objects that
away from every other point objects that are bound together by chemical forces or
are bound together by chemical forces or
are bound together by chemical forces or gravitational forces space expands out
gravitational forces space expands out
gravitational forces space expands out from under them that’s why we’re not
from under them that’s why we’re not
from under them that’s why we’re not expanded happily but if every object is
expanded happily but if every object is
expanded happily but if every object is expanding from every other object then
expanding from every other object then
expanding from every other object then if you project backwards in time things
if you project backwards in time things
if you project backwards in time things must have been once much much denser and
must have been once much much denser and
must have been once much much denser and therefore much much hotter and that is
therefore much much hotter and that is
therefore much much hotter and that is the fundamental reason for believing in
the fundamental reason for believing in
the fundamental reason for believing in the idea of a big bang that once the
the idea of a big bang that once the
the idea of a big bang that once the universe was extraordinarily hot and
universe was extraordinarily hot and
universe was extraordinarily hot and dense in fact once the universe was as
dense in fact once the universe was as
dense in fact once the universe was as hot and dense as the surface of the Sun
hot and dense as the surface of the Sun
hot and dense as the surface of the Sun and the light emitted at that time which
and the light emitted at that time which
and the light emitted at that time which is what’s visible light at the time has
is what’s visible light at the time has
is what’s visible light at the time has been traveling through the universe and
been traveling through the universe and
been traveling through the universe and getting stretched out as it travels so
getting stretched out as it travels so
getting stretched out as it travels so that it is now shifted from the visible
that it is now shifted from the visible
that it is now shifted from the visible light to the infrared light to the
light to the infrared light to the
light to the infrared light to the microwave and this
microwave and this
microwave and this the Cosmic Microwave Background the very
the Cosmic Microwave Background the very
the Cosmic Microwave Background the very small variations in which were measured
small variations in which were measured
small variations in which were measured in this map by the Ponk satellite and
in this map by the Ponk satellite and
in this map by the Ponk satellite and have been measured over the years okay
have been measured over the years okay
have been measured over the years okay so we have a universe that’s expanding
so we have a universe that’s expanding
so we have a universe that’s expanding from an origin when this was first
from an origin when this was first
from an origin when this was first proposed it was denounced as creationist
proposed it was denounced as creationist
proposed it was denounced as creationist and indeed it was proposed by a Catholic
and indeed it was proposed by a Catholic
and indeed it was proposed by a Catholic priest Father lometa and yet all the
priest Father lometa and yet all the
priest Father lometa and yet all the evidence that we have points to the idea
evidence that we have points to the idea
evidence that we have points to the idea that the universe Kate started at a
that the universe Kate started at a
that the universe Kate started at a definite time extraordinarily hot
definite time extraordinarily hot
definite time extraordinarily hot extraordinarily dense furthermore
extraordinarily dense furthermore
extraordinarily dense furthermore furthermore most of the matter in the
furthermore most of the matter in the
furthermore most of the matter in the universe is not the stuff we are made of
universe is not the stuff we are made of
universe is not the stuff we are made of it’s not Adams of any sort the first
it’s not Adams of any sort the first
it’s not Adams of any sort the first person who realized this was this guy up
person who realized this was this guy up
person who realized this was this guy up here fritz zwicky back in the 1930s he
here fritz zwicky back in the 1930s he
here fritz zwicky back in the 1930s he looked at galaxy clusters and realized
looked at galaxy clusters and realized
looked at galaxy clusters and realized that there was far too much mass in them
that there was far too much mass in them
that there was far too much mass in them they couldn’t be explained by the
they couldn’t be explained by the
they couldn’t be explained by the visible galaxies he measured how fast
visible galaxies he measured how fast
visible galaxies he measured how fast galaxies were orbiting using their red
galaxies were orbiting using their red
galaxies were orbiting using their red shifts and compared to how much mass was
shifts and compared to how much mass was
shifts and compared to how much mass was in the stars whose brightness he could
in the stars whose brightness he could
in the stars whose brightness he could measure and the answer came out it was a
measure and the answer came out it was a
measure and the answer came out it was a hundred times wrong there was a hundred
hundred times wrong there was a hundred
hundred times wrong there was a hundred times more mass in that cluster than
times more mass in that cluster than
times more mass in that cluster than could be accounted for by the visible
could be accounted for by the visible
could be accounted for by the visible galaxies well back then first of all he
galaxies well back then first of all he
galaxies well back then first of all he was a famously follow mouth and paranoid
was a famously follow mouth and paranoid
was a famously follow mouth and paranoid guy who nobody liked and second we
guy who nobody liked and second we
guy who nobody liked and second we didn’t really understand galaxy clusters
didn’t really understand galaxy clusters
didn’t really understand galaxy clusters so everybody just sort of shoved it to
so everybody just sort of shoved it to
so everybody just sort of shoved it to the side until the 1970s when Vera Rubin
the side until the 1970s when Vera Rubin
the side until the 1970s when Vera Rubin comes along and looks at individual
comes along and looks at individual
comes along and looks at individual galaxies and how stars orbit around the
galaxies and how stars orbit around the
galaxies and how stars orbit around the center in those galaxies and she finds
center in those galaxies and she finds
center in those galaxies and she finds that if the stars were in the galaxy
that if the stars were in the galaxy
that if the stars were in the galaxy they should if the stars were the only
they should if the stars were the only
they should if the stars were the only mass in the galaxy they should orbit
mass in the galaxy they should orbit
mass in the galaxy they should orbit like this line labeled disk and yet they
like this line labeled disk and yet they
like this line labeled disk and yet they don’t they orbit like the top line
don’t they orbit like the top line
don’t they orbit like the top line meaning there’s lots of extra
meaning there’s lots of extra
meaning there’s lots of extra ass after that point people started
ass after that point people started
ass after that point people started taking the idea of dark matter seriously
taking the idea of dark matter seriously
taking the idea of dark matter seriously given the timing we’re going to keep
given the timing we’re going to keep
given the timing we’re going to keep going because that was bad enough but
going because that was bad enough but
going because that was bad enough but still we understood that now we know
still we understood that now we know
still we understood that now we know where most where all the mass is and
where most where all the mass is and
where most where all the mass is and mass will act on the expansion of the
mass will act on the expansion of the
mass will act on the expansion of the universe to slow it down because gravity
universe to slow it down because gravity
universe to slow it down because gravity is pulling it in now to measure the mass
is pulling it in now to measure the mass
is pulling it in now to measure the mass well it would be good to know how
well it would be good to know how
well it would be good to know how quickly the universe is decelerating how
quickly the universe is decelerating how
quickly the universe is decelerating how quickly that expansion is slowing down
quickly that expansion is slowing down
quickly that expansion is slowing down because of all the mass in the universe
because of all the mass in the universe
because of all the mass in the universe and so a number of teams in the 1990s
and so a number of teams in the 1990s
and so a number of teams in the 1990s set out to measure the deceleration of
set out to measure the deceleration of
set out to measure the deceleration of the universe by measuring galaxies at
the universe by measuring galaxies at
the universe by measuring galaxies at great distances and finding their red
great distances and finding their red
great distances and finding their red shifts they used a certain type of
shifts they used a certain type of
shifts they used a certain type of supernova it could be calibrated to
supernova it could be calibrated to
supernova it could be calibrated to reveal its absolute luminosity how
reveal its absolute luminosity how
reveal its absolute luminosity how bright it actually was and compare it to
bright it actually was and compare it to
bright it actually was and compare it to its apparent luminosity and they went
its apparent luminosity and they went
its apparent luminosity and they went out and found lots of supernovae with
out and found lots of supernovae with
out and found lots of supernovae with great effort and built robotic
great effort and built robotic
great effort and built robotic telescopes to do this and at the end it
telescopes to do this and at the end it
telescopes to do this and at the end it came down to this guy over on the Left
came down to this guy over on the Left
came down to this guy over on the Left who was a graduate student in the group
who was a graduate student in the group
who was a graduate student in the group taking all the data putting it together
taking all the data putting it together
taking all the data putting it together to measure the deceleration of the
to measure the deceleration of the
to measure the deceleration of the universe and so late one night he
universe and so late one night he
universe and so late one night he finishes the program and adds up all the
finishes the program and adds up all the
finishes the program and adds up all the numbers and gets out the answer and he’s
numbers and gets out the answer and he’s
numbers and gets out the answer and he’s got a sign error the deceleration is
got a sign error the deceleration is
got a sign error the deceleration is negative it’s not a deceleration at all
negative it’s not a deceleration at all
negative it’s not a deceleration at all it’s an acceleration well he goes back
it’s an acceleration well he goes back
it’s an acceleration well he goes back and gets his boss and his boss’s boss
and gets his boss and his boss’s boss
and gets his boss and his boss’s boss and they all check the numbers and it
and they all check the numbers and it
and they all check the numbers and it remains an acceleration it turns out
remains an acceleration it turns out
remains an acceleration it turns out that there’s something else besides
that there’s something else besides
that there’s something else besides matter and it is dominating the dynamics
matter and it is dominating the dynamics
matter and it is dominating the dynamics of our universe we’ve given it a label
of our universe we’ve given it a label
of our universe we’ve given it a label we’ve called it dark energy its energy
we’ve called it dark energy its energy
we’ve called it dark energy its energy that we cannot detect so it’s dark we
that we cannot detect so it’s dark we
that we cannot detect so it’s dark we know that to about ten percent it hasn’t
know that to about ten percent it hasn’t
know that to about ten percent it hasn’t changed over time there’s not more and
changed over time there’s not more and
changed over time there’s not more and more of it but yet it is causing our
more of it but yet it is causing our
more of it but yet it is causing our universe to go faster and faster so we
universe to go faster and faster so we
universe to go faster and faster so we are starting to characterize it more and
are starting to characterize it more and
are starting to characterize it more and more accurately but we still don’t know
more accurately but we still don’t know
more accurately but we still don’t know physically why it’s there why it is as
physically why it’s there why it is as
physically why it’s there why it is as strong as it is now we’ve now
strong as it is now we’ve now
strong as it is now we’ve now accomplished multiple independent
accomplished multiple independent
accomplished multiple independent measurements of how much dark matter
measurements of how much dark matter
measurements of how much dark matter there is and how much matter there is
there is and how much matter there is
there is and how much matter there is and this is Cosmic Microwave Background
and this is Cosmic Microwave Background
and this is Cosmic Microwave Background this is the supernova the other one is
this is the supernova the other one is
this is the supernova the other one is measuring the positions of galaxies and
measuring the positions of galaxies and
measuring the positions of galaxies and how fast they’re falling together they
how fast they’re falling together they
how fast they’re falling together they come together in that very small error
come together in that very small error
come together in that very small error circle and that small error circle is a
circle and that small error circle is a
circle and that small error circle is a place that is extraordinarily odd it is
place that is extraordinarily odd it is
place that is extraordinarily odd it is a universe dominated by dark energy and
a universe dominated by dark energy and
a universe dominated by dark energy and dark matter everything that we know
dark matter everything that we know
dark matter everything that we know about and can detect at this point is in
about and can detect at this point is in
about and can detect at this point is in that little 4% sliver of which only this
that little 4% sliver of which only this
that little 4% sliver of which only this little red sliver over here is the heavy
little red sliver over here is the heavy
little red sliver over here is the heavy elements the carb in the nitrogen the
elements the carb in the nitrogen the
elements the carb in the nitrogen the oxygen all the stuff that makes up us
oxygen all the stuff that makes up us
oxygen all the stuff that makes up us our planets aside from hydrogen most of
our planets aside from hydrogen most of
our planets aside from hydrogen most of the universe has not yet been detected
the universe has not yet been detected
the universe has not yet been detected Dark Matter is perhaps on the cusp of
Dark Matter is perhaps on the cusp of
Dark Matter is perhaps on the cusp of being detected there are many efforts
being detected there are many efforts
being detected there are many efforts being made to directly detect a dark
being made to directly detect a dark
being made to directly detect a dark matter particle they may be successful
matter particle they may be successful
matter particle they may be successful possibly soon dark energy we’re still in
possibly soon dark energy we’re still in
possibly soon dark energy we’re still in the in the mode of I’m a blind person
the in the mode of I’m a blind person
the in the mode of I’m a blind person and I’m feeling the elephant is it have
and I’m feeling the elephant is it have
and I’m feeling the elephant is it have a long skinny bit is it a big hard bit
a long skinny bit is it a big hard bit
a long skinny bit is it a big hard bit what is it that’s how we’re living in
what is it that’s how we’re living in
what is it that’s how we’re living in the question of understanding
the question of understanding
the question of understanding our own universe thank you
our own universe thank you
our own universe thank you [Applause]
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