[Music] at first scientists thought it was a
at first scientists thought it was a
at first scientists thought it was a comet but it had no tail and so it
comet but it had no tail and so it
comet but it had no tail and so it couldn’t be a comment and people
couldn’t be a comment and people
couldn’t be a comment and people concluded it must be an asteroid now I’m
concluded it must be an asteroid now I’m
concluded it must be an asteroid now I’m known as moooo moooo mwah
known as moooo moooo mwah
known as moooo moooo mwah it had hurled down from above the solar
it had hurled down from above the solar
it had hurled down from above the solar system narrowly missing the Sun coming
system narrowly missing the Sun coming
system narrowly missing the Sun coming within the orbit of mercury and that was
within the orbit of mercury and that was
within the orbit of mercury and that was whizzing past the earth just 30 million
whizzing past the earth just 30 million
whizzing past the earth just 30 million kilometres away
astronomers believe it is made of rock
astronomers believe it is made of rock but might it be made instead of dark
but might it be made instead of dark
but might it be made instead of dark matter when we look out at galaxies much
matter when we look out at galaxies much
matter when we look out at galaxies much like our own Milky Way they looks many
like our own Milky Way they looks many
like our own Milky Way they looks many of them looks something like this spiral
of them looks something like this spiral
of them looks something like this spiral galaxy m81 if you went to an amusement
galaxy m81 if you went to an amusement
galaxy m81 if you went to an amusement park and we’re about to get on one of
park and we’re about to get on one of
park and we’re about to get on one of those fun rides where we’re a swing goes
those fun rides where we’re a swing goes
those fun rides where we’re a swing goes goes goes whizzing around a central
goes goes whizzing around a central
goes goes whizzing around a central pillar and you’re held on by nice strong
pillar and you’re held on by nice strong
pillar and you’re held on by nice strong chains if you got up to the ride and
chains if you got up to the ride and
chains if you got up to the ride and notice that instead of chains it was
notice that instead of chains it was
notice that instead of chains it was held together by dental floss you
held together by dental floss you
held together by dental floss you probably wouldn’t want to get on that
probably wouldn’t want to get on that
probably wouldn’t want to get on that ride you’d be too worried that those
ride you’d be too worried that those
ride you’d be too worried that those that dental floss would break allowing
that dental floss would break allowing
that dental floss would break allowing you to go hurtling out into space and
you to go hurtling out into space and
you to go hurtling out into space and crash to the ground and yet when we look
crash to the ground and yet when we look
crash to the ground and yet when we look at spiral galaxies like this one we see
at spiral galaxies like this one we see
at spiral galaxies like this one we see that they are spinning far too fast to
that they are spinning far too fast to
that they are spinning far too fast to be held together by the gravity of the
be held together by the gravity of the
be held together by the gravity of the stars and gas and dust that must be
stars and gas and dust that must be
stars and gas and dust that must be providing gravity well there’s two
providing gravity well there’s two
providing gravity well there’s two possibilities one is that we don’t
possibilities one is that we don’t
possibilities one is that we don’t understand the laws of gravity properly
understand the laws of gravity properly
understand the laws of gravity properly that we need to change general activity
that we need to change general activity
that we need to change general activity Einstein’s theory of how gravity works
Einstein’s theory of how gravity works
Einstein’s theory of how gravity works his improvement on Newton’s were that in
his improvement on Newton’s were that in
his improvement on Newton’s were that in fact the laws of gravity on these very
fact the laws of gravity on these very
fact the laws of gravity on these very large scales aren’t quite the same as
large scales aren’t quite the same as
large scales aren’t quite the same as they are within the solar system or on
they are within the solar system or on
they are within the solar system or on earth but subtly different that’s
earth but subtly different that’s
earth but subtly different that’s possible but we have so far failed to
possible but we have so far failed to
possible but we have so far failed to change those laws of gravity in a way
change those laws of gravity in a way
change those laws of gravity in a way that hangs together and so the other
that hangs together and so the other
that hangs together and so the other possibility is that there’s a lot of
possibility is that there’s a lot of
possibility is that there’s a lot of missing matter inside this galaxy and
missing matter inside this galaxy and
missing matter inside this galaxy and inside of every galaxy we see we call
inside of every galaxy we see we call
inside of every galaxy we see we call that missing matter dark matter because
that missing matter dark matter because
that missing matter dark matter because we can’t see it now for a long time we
we can’t see it now for a long time we
we can’t see it now for a long time we thought that that missing matter must be
thought that that missing matter must be
thought that that missing matter must be particles too many particles
particles too many particles
particles too many particles that are whizzing through space that are
that are whizzing through space that are
that are whizzing through space that are filling this room and the only reason we
filling this room and the only reason we
filling this room and the only reason we don’t feel them is that they are so
don’t feel them is that they are so
don’t feel them is that they are so weakly interacting that they manage to
weakly interacting that they manage to
weakly interacting that they manage to pass through the earth
pass through the earth
pass through the earth we have particles like that that we know
we have particles like that that we know
we have particles like that that we know about called neutrinos they come from
about called neutrinos they come from
about called neutrinos they come from the center of the Sun go unimpeded
the center of the Sun go unimpeded
the center of the Sun go unimpeded through the Sun most of them go unheeded
through the Sun most of them go unheeded
through the Sun most of them go unheeded through the earth and they can travel
through the earth and they can travel
through the earth and they can travel through light-years of ordinary material
through light-years of ordinary material
through light-years of ordinary material and it’s only by many many of them to
and it’s only by many many of them to
and it’s only by many many of them to pass through the detectors we build that
pass through the detectors we build that
pass through the detectors we build that we’ve never been able to see them so
we’ve never been able to see them so
we’ve never been able to see them so we’ve thought for a long time that dark
we’ve thought for a long time that dark
we’ve thought for a long time that dark matter must be like that and so we built
matter must be like that and so we built
matter must be like that and so we built detectors like the one on the left and
detectors like the one on the left and
detectors like the one on the left and we put them deep underground in old
we put them deep underground in old
we put them deep underground in old mines or underneath dams where cosmic
mines or underneath dams where cosmic
mines or underneath dams where cosmic rays can’t get to them and we’ve waited
rays can’t get to them and we’ve waited
rays can’t get to them and we’ve waited for for dark matter particles to hit the
for for dark matter particles to hit the
for for dark matter particles to hit the nuclei or the electrons of these dark
nuclei or the electrons of these dark
nuclei or the electrons of these dark matter detectors and heat them up just a
matter detectors and heat them up just a
matter detectors and heat them up just a tiny little bit because they’re an
tiny little bit because they’re an
tiny little bit because they’re an incredibly sensitive thermometers or
incredibly sensitive thermometers or
incredibly sensitive thermometers or make a very tiny sound because they’re
make a very tiny sound because they’re
make a very tiny sound because they’re incredibly sensitive microphones and so
incredibly sensitive microphones and so
incredibly sensitive microphones and so far after 40 years we failed to register
far after 40 years we failed to register
far after 40 years we failed to register anything in these dark matter detectors
anything in these dark matter detectors
anything in these dark matter detectors we’ve also built enormous machines
we’ve also built enormous machines
we’ve also built enormous machines called in this particular one called the
called in this particular one called the
called in this particular one called the Large Hadron Collider at the CERN in
Large Hadron Collider at the CERN in
Large Hadron Collider at the CERN in Geneva hoping to make particles of dark
Geneva hoping to make particles of dark
Geneva hoping to make particles of dark matter well we’ve made lots of things at
matter well we’ve made lots of things at
matter well we’ve made lots of things at the Large Hadron Collider and
the Large Hadron Collider and
the Large Hadron Collider and particularly we’ve discovered the Higgs
particularly we’ve discovered the Higgs
particularly we’ve discovered the Higgs boson the last unknown particle
boson the last unknown particle
boson the last unknown particle undiscovered particle of the standard
undiscovered particle of the standard
undiscovered particle of the standard model but so far we haven’t made any
model but so far we haven’t made any
model but so far we haven’t made any Dark Matter what could it be that our
Dark Matter what could it be that our
Dark Matter what could it be that our idea of what dark matter is is just
idea of what dark matter is is just
idea of what dark matter is is just wrong that it’s not little particles
wrong that it’s not little particles
wrong that it’s not little particles whizzing through space but large chunks
whizzing through space but large chunks
whizzing through space but large chunks of matter like this one this is an
of matter like this one this is an
of matter like this one this is an artist’s conception of a neutron star
artist’s conception of a neutron star
artist’s conception of a neutron star now it’s not a very good picture because
now it’s not a very good picture because
now it’s not a very good picture because I’m not much of an artist I’m a
I’m not much of an artist I’m a
I’m not much of an artist I’m a physicist but what is it what is it
physicist but what is it what is it
physicist but what is it what is it about a neutron star that makes a good
about a neutron star that makes a good
about a neutron star that makes a good dark matter or what is it about pieces
dark matter or what is it about pieces
dark matter or what is it about pieces of pieces of neutron star smaller
of pieces of neutron star smaller
of pieces of neutron star smaller neutron stars chunks of nuclear matter
neutron stars chunks of nuclear matter
neutron stars chunks of nuclear matter much like the nuclei at the centre of
much like the nuclei at the centre of
much like the nuclei at the centre of atoms but bigger that would make them
atoms but bigger that would make them
atoms but bigger that would make them good dark matter after all didn’t I tell
good dark matter after all didn’t I tell
good dark matter after all didn’t I tell you that dark matter had to be dark that
you that dark matter had to be dark that
you that dark matter had to be dark that you couldn’t see it and we can see
you couldn’t see it and we can see
you couldn’t see it and we can see neutron stars we can
neutron stars we can
neutron stars we can see nuclei but actually neutron stars
see nuclei but actually neutron stars
see nuclei but actually neutron stars and things like it chunks the nuclear
and things like it chunks the nuclear
and things like it chunks the nuclear matter make wonderful dark matter
matter make wonderful dark matter
matter make wonderful dark matter because although you can see the nuclei
because although you can see the nuclei
because although you can see the nuclei the matter at the surface you don’t get
the matter at the surface you don’t get
the matter at the surface you don’t get to see the inside
to see the inside
to see the inside so in fact most of them most of the
so in fact most of them most of the
so in fact most of them most of the matter is invisible the other thing is
matter is invisible the other thing is
matter is invisible the other thing is unlike particles which are very have
unlike particles which are very have
unlike particles which are very have very little mass and so there have to be
very little mass and so there have to be
very little mass and so there have to be lots and lots of lots of them a neutron
lots and lots of lots of them a neutron
lots and lots of lots of them a neutron star is really big if the neutron star
star is really big if the neutron star
star is really big if the neutron star was a dark matter we would only need one
was a dark matter we would only need one
was a dark matter we would only need one of them in every thousand cubic
of them in every thousand cubic
of them in every thousand cubic light-years and so there’s not much
light-years and so there’s not much
light-years and so there’s not much chance of it hitting our detector or
chance of it hitting our detector or
chance of it hitting our detector or even passing through the solar system
even passing through the solar system
even passing through the solar system very often now if they were smaller
very often now if they were smaller
very often now if they were smaller chunks of nuclear matter its chunks of
chunks of nuclear matter its chunks of
chunks of nuclear matter its chunks of neutron star they would pass through
neutron star they would pass through
neutron star they would pass through more often and we might have a hope of
more often and we might have a hope of
more often and we might have a hope of seeing them we would want really big
seeing them we would want really big
seeing them we would want really big detectors things that are so large that
detectors things that are so large that
detectors things that are so large that it was pretty much inevitable that dark
it was pretty much inevitable that dark
it was pretty much inevitable that dark matter would hit one of them well here
matter would hit one of them well here
matter would hit one of them well here are two really good big detectors the
are two really good big detectors the
are two really good big detectors the first one is the planet we live on the
first one is the planet we live on the
first one is the planet we live on the planet Earth
planet Earth
planet Earth and the other is the moon and they’re
and the other is the moon and they’re
and the other is the moon and they’re nice and close to us and so we can
nice and close to us and so we can
nice and close to us and so we can imagine putting putting instruments on
imagine putting putting instruments on
imagine putting putting instruments on them to use them as dark matter
them to use them as dark matter
them to use them as dark matter detectors well what would it look like
detectors well what would it look like
detectors well what would it look like if dark matter hit the earth it depends
if dark matter hit the earth it depends
if dark matter hit the earth it depends where it hits and so we can use the
where it hits and so we can use the
where it hits and so we can use the different places that it could hit as
different places that it could hit as
different places that it could hit as different ways of looking for dark
different ways of looking for dark
different ways of looking for dark matter
matter
matter for example dark matter streaking
for example dark matter streaking
for example dark matter streaking through the atmosphere would heat up and
through the atmosphere would heat up and
through the atmosphere would heat up and it would heat the atmosphere around it
it would heat the atmosphere around it
it would heat the atmosphere around it and it might glow just like a meteor now
and it might glow just like a meteor now
and it might glow just like a meteor now you might say well are the meteors we’re
you might say well are the meteors we’re
you might say well are the meteors we’re seeing dark matter
seeing dark matter
seeing dark matter the thing is meteors from the solar
the thing is meteors from the solar
the thing is meteors from the solar system move relatively slowly only 20
system move relatively slowly only 20
system move relatively slowly only 20 kilometers a second or 30 kilometers a
kilometers a second or 30 kilometers a
kilometers a second or 30 kilometers a second
second
second whereas dark matter would might be
whereas dark matter would might be
whereas dark matter would might be moving 300 or 400 kilometers a second so
moving 300 or 400 kilometers a second so
moving 300 or 400 kilometers a second so we can tell whether a meteor was made of
we can tell whether a meteor was made of
we can tell whether a meteor was made of dark matter but probably if if we were
dark matter but probably if if we were
dark matter but probably if if we were having enough of these to detect they
having enough of these to detect they
having enough of these to detect they would be much smaller chunks and they
would be much smaller chunks and they
would be much smaller chunks and they wouldn’t glow as brightly as a meteor so
wouldn’t glow as brightly as a meteor so
wouldn’t glow as brightly as a meteor so we would have to use very large
we would have to use very large
we would have to use very large detectors that look for things like
detectors that look for things like
detectors that look for things like meteors they’re called cosmic ray
meteors they’re called cosmic ray
meteors they’re called cosmic ray detectors ultra high cosmic ray
detectors ultra high cosmic ray
detectors ultra high cosmic ray detectors them we built
detectors them we built
detectors them we built huge ones we have one down in southern
huge ones we have one down in southern
huge ones we have one down in southern Argentina that’s tens of thousands of
Argentina that’s tens of thousands of
Argentina that’s tens of thousands of square kilometers staring out into space
square kilometers staring out into space
square kilometers staring out into space looking for ultra high-energy cosmic
looking for ultra high-energy cosmic
looking for ultra high-energy cosmic rays that can also look for these chunks
rays that can also look for these chunks
rays that can also look for these chunks of matter as dark matter we’re planning
of matter as dark matter we’re planning
of matter as dark matter we’re planning to build one that looks down from space
to build one that looks down from space
to build one that looks down from space at a huge fraction of the Earth’s
at a huge fraction of the Earth’s
at a huge fraction of the Earth’s surface of the atmosphere and we can
surface of the atmosphere and we can
surface of the atmosphere and we can watch for those cosmic rays or for these
watch for those cosmic rays or for these
watch for those cosmic rays or for these chunks of dark matter running through
chunks of dark matter running through
chunks of dark matter running through the atmosphere incredibly quickly much
the atmosphere incredibly quickly much
the atmosphere incredibly quickly much faster than any and than any meteor but
faster than any and than any meteor but
faster than any and than any meteor but much slower than any typical cosmic ray
much slower than any typical cosmic ray
much slower than any typical cosmic ray and we can look for the glow of dark
and we can look for the glow of dark
and we can look for the glow of dark matter passing through the atmosphere we
matter passing through the atmosphere we
matter passing through the atmosphere we also see craters for example on the moon
also see craters for example on the moon
also see craters for example on the moon the moon is a wonderful detector of
the moon is a wonderful detector of
the moon is a wonderful detector of things that hit it because they leave
things that hit it because they leave
things that hit it because they leave behind craters now the different thing
behind craters now the different thing
behind craters now the different thing about dark matter is if a chunk of dark
about dark matter is if a chunk of dark
about dark matter is if a chunk of dark matter hit the moon it would be moving
matter hit the moon it would be moving
matter hit the moon it would be moving it would be so dense and moving so fast
it would be so dense and moving so fast
it would be so dense and moving so fast that not only would go into the moon it
that not only would go into the moon it
that not only would go into the moon it would come out the other side not too
would come out the other side not too
would come out the other side not too many things do that imagine having a
many things do that imagine having a
many things do that imagine having a piece of jell-o and sending a really
piece of jell-o and sending a really
piece of jell-o and sending a really really fast tiny little VB through the
really fast tiny little VB through the
really fast tiny little VB through the jello what would happen if you went in
jello what would happen if you went in
jello what would happen if you went in you’d make a little tiny hole but as you
you’d make a little tiny hole but as you
you’d make a little tiny hole but as you went out you’d make a big splat we can
went out you’d make a big splat we can
went out you’d make a big splat we can imagine looking on the moon and on
imagine looking on the moon and on
imagine looking on the moon and on Mercury and on other bodies for to see
Mercury and on other bodies for to see
Mercury and on other bodies for to see are there any splats like that are there
are there any splats like that are there
are there any splats like that are there any distinctive craters that look like
any distinctive craters that look like
any distinctive craters that look like they came from the inside rather than
they came from the inside rather than
they came from the inside rather than the outside now there are other more
the outside now there are other more
the outside now there are other more mundane you know everyday ways that we
mundane you know everyday ways that we
mundane you know everyday ways that we can look for dark matter for example you
can look for dark matter for example you
can look for dark matter for example you might want to go home and look at your
might want to go home and look at your
might want to go home and look at your windows because as a little chunk of
windows because as a little chunk of
windows because as a little chunk of dark matter passed through your window
dark matter passed through your window
dark matter passed through your window it would comment a very very tiny
it would comment a very very tiny
it would comment a very very tiny cylinder through your winter a little
cylinder through your winter a little
cylinder through your winter a little tiny track and so if we got all of you
tiny track and so if we got all of you
tiny track and so if we got all of you to go home and look at the windows in
to go home and look at the windows in
to go home and look at the windows in your homes and in your offices and in
your homes and in your offices and in
your homes and in your offices and in your friends offices in their homes we
your friends offices in their homes we
your friends offices in their homes we might be able to by looking at these
might be able to by looking at these
might be able to by looking at these vast expanses of windows that fill our
vast expanses of windows that fill our
vast expanses of windows that fill our cities be able to tell whether particles
cities be able to tell whether particles
cities be able to tell whether particles of dark matter had come hurtling through
of dark matter had come hurtling through
of dark matter had come hurtling through them leaving behind these little tracks
them leaving behind these little tracks
them leaving behind these little tracks what about muah-muah
what about muah-muah
what about muah-muah well it may or may not be a chunk of
well it may or may not be a chunk of
well it may or may not be a chunk of dark matter it’s going to be very hard
dark matter it’s going to be very hard
dark matter it’s going to be very hard for us to tell unless we take a trip
for us to tell unless we take a trip
for us to tell unless we take a trip there
there
there and people are planning to send a
and people are planning to send a
and people are planning to send a mission if they can to a mu a mu and try
mission if they can to a mu a mu and try
mission if they can to a mu a mu and try to catch it but whether or not o Momoa
to catch it but whether or not o Momoa
to catch it but whether or not o Momoa is a chunk of dark matter there’s a very
is a chunk of dark matter there’s a very
is a chunk of dark matter there’s a very good chance that our galaxy is being
good chance that our galaxy is being
good chance that our galaxy is being held together by stuff that we simply
held together by stuff that we simply
held together by stuff that we simply cannot see so far and that is out there
cannot see so far and that is out there
cannot see so far and that is out there for us to discover and we hope to do
for us to discover and we hope to do
for us to discover and we hope to do that soon thank you
”
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