Shedding light on dark matter - Patricia Burchat
[Music]
[Music]
as<00:00:16.000> a<00:00:16.119> particle<00:00:16.520> physicist<00:00:17.400> I<00:00:17.560> study<00:00:18.080> the
as a particle physicist I study the
as a particle physicist I study the
elementary<00:00:18.720> particles<00:00:19.439> and<00:00:19.600> how<00:00:19.760> they
elementary particles and how they
elementary particles and how they
interact<00:00:20.359> on<00:00:20.480> the<00:00:20.600> most<00:00:20.800> fundamental<00:00:21.320> level
interact on the most fundamental level
interact on the most fundamental level
for<00:00:22.160> most<00:00:22.320> of<00:00:22.480> my<00:00:22.640> research<00:00:23.080> career<00:00:23.720> I've<00:00:23.880> been
for most of my research career I've been
for most of my research career I've been
using<00:00:24.439> accelerators<00:00:25.080> such<00:00:25.240> as<00:00:25.400> the<00:00:25.519> electron
using accelerators such as the electron
using accelerators such as the electron
accelerator<00:00:26.439> at<00:00:26.560> Stanford<00:00:26.960> University<00:00:27.480> just
accelerator at Stanford University just
accelerator at Stanford University just
up<00:00:27.840> the<00:00:27.960> road<00:00:28.599> to<00:00:28.760> study<00:00:29.119> things<00:00:29.359> on<00:00:29.480> the<00:00:29.640> small
up the road to study things on the small
up the road to study things on the small
smallest<00:00:30.519> scale<00:00:31.359> but<00:00:31.480> more<00:00:31.679> recently<00:00:32.239> I've
smallest scale but more recently I've
smallest scale but more recently I've
been<00:00:32.520> turning<00:00:32.880> my<00:00:33.040> attention<00:00:33.920> to<00:00:34.320> the
been turning my attention to the
been turning my attention to the
universe<00:00:35.079> on<00:00:35.239> the<00:00:35.399> largest<00:00:35.840> scale<00:00:36.480> because<00:00:36.719> as
universe on the largest scale because as
universe on the largest scale because as
I'll<00:00:37.040> explain<00:00:37.360> to<00:00:37.520> you<00:00:38.079> the<00:00:38.239> questions<00:00:38.760> on<00:00:38.920> the
I'll explain to you the questions on the
I'll explain to you the questions on the
smallest<00:00:39.399> and<00:00:39.520> the<00:00:39.640> largest<00:00:39.960> scale<00:00:40.239> are
smallest and the largest scale are
smallest and the largest scale are
actually<00:00:40.840> very<00:00:41.120> connected<00:00:42.079> okay<00:00:42.719> so<00:00:43.079> I'm
actually very connected okay so I'm
actually very connected okay so I'm
going<00:00:43.320> to<00:00:43.440> tell<00:00:43.600> you<00:00:43.800> about<00:00:44.320> our<00:00:44.600> 21st<00:00:45.160> century
going to tell you about our 21st century
going to tell you about our 21st century
view<00:00:45.719> of<00:00:45.879> the<00:00:46.079> universe<00:00:47.079> what<00:00:47.239> it's<00:00:47.440> made<00:00:47.640> of
view of the universe what it's made of
view of the universe what it's made of
and<00:00:48.239> what<00:00:48.399> the<00:00:48.520> big<00:00:48.760> questions<00:00:49.199> in<00:00:49.280> the
and what the big questions in the
and what the big questions in the
physical<00:00:49.800> sciences<00:00:50.239> are<00:00:50.440> or<00:00:50.559> at<00:00:50.640> least<00:00:50.800> some
physical sciences are or at least some
physical sciences are or at least some
of<00:00:51.000> the<00:00:51.120> big<00:00:51.640> questions<00:00:52.640> so<00:00:53.239> recently<00:00:54.039> we<00:00:54.160> have
of the big questions so recently we have
of the big questions so recently we have
realized<00:00:55.199> that<00:00:55.359> the<00:00:55.520> ordinary<00:00:56.039> matter<00:00:56.320> in<00:00:56.399> the
realized that the ordinary matter in the
realized that the ordinary matter in the
universe<00:00:56.960> and<00:00:57.079> by<00:00:57.239> ordinary<00:00:57.719> matter<00:00:58.320> I<00:00:58.440> mean
universe and by ordinary matter I mean
universe and by ordinary matter I mean
you<00:00:59.719> okay<00:01:00.239> me<00:01:00.840> the<00:01:01.039> planets<00:01:01.559> the<00:01:01.719> Stars<00:01:02.120> the
you okay me the planets the Stars the
you okay me the planets the Stars the
galaxies<00:01:02.760> the<00:01:02.840> ordinary<00:01:03.280> matter<00:01:03.640> makes<00:01:03.840> up
galaxies the ordinary matter makes up
galaxies the ordinary matter makes up
only<00:01:04.360> a<00:01:04.519> few<00:01:04.799> percent<00:01:05.280> of<00:01:05.400> the<00:01:05.560> content<00:01:05.920> of<00:01:06.040> the
only a few percent of the content of the
only a few percent of the content of the
universe<00:01:08.080> almost<00:01:08.320> a<00:01:08.479> quarter<00:01:09.000> or
universe almost a quarter or
universe almost a quarter or
approximately<00:01:09.600> a<00:01:09.720> quarter<00:01:10.400> of<00:01:10.560> the<00:01:10.680> matter<00:01:10.960> in
approximately a quarter of the matter in
approximately a quarter of the matter in
the<00:01:11.200> universe<00:01:11.759> is<00:01:11.920> stuff<00:01:12.159> that's<00:01:12.400> Invisible
the universe is stuff that's Invisible
the universe is stuff that's Invisible
by<00:01:13.560> invisible<00:01:14.080> I<00:01:14.200> mean<00:01:14.560> it<00:01:14.720> doesn't<00:01:15.360> absorb<00:01:15.880> in
by invisible I mean it doesn't absorb in
by invisible I mean it doesn't absorb in
the<00:01:16.040> electromagnetic<00:01:16.720> spectrum<00:01:17.200> it<00:01:17.320> doesn't
the electromagnetic spectrum it doesn't
the electromagnetic spectrum it doesn't
emit<00:01:17.880> in<00:01:17.960> the<00:01:18.080> electromagnetic<00:01:18.759> spectrum<00:01:19.159> it
emit in the electromagnetic spectrum it
emit in the electromagnetic spectrum it
doesn't<00:01:19.600> reflect<00:01:20.520> it<00:01:20.640> doesn't<00:01:20.920> interact<00:01:21.280> with
doesn't reflect it doesn't interact with
doesn't reflect it doesn't interact with
the<00:01:21.439> electromagnetic<00:01:22.119> spectrum<00:01:22.479> which<00:01:22.600> is
the electromagnetic spectrum which is
the electromagnetic spectrum which is
what<00:01:22.840> we<00:01:23.040> use<00:01:23.560> to<00:01:23.759> detect<00:01:24.119> things<00:01:24.360> doesn't
what we use to detect things doesn't
what we use to detect things doesn't
interact<00:01:25.000> at<00:01:25.119> all<00:01:25.640> so<00:01:25.759> how<00:01:25.880> do<00:01:26.000> we<00:01:26.119> know<00:01:26.280> it's
interact at all so how do we know it's
interact at all so how do we know it's
there<00:01:27.040> we<00:01:27.200> know<00:01:27.360> it's<00:01:27.640> there<00:01:27.880> by<00:01:28.040> its
there we know it's there by its
there we know it's there by its
gravitational<00:01:29.159> effects<00:01:29.640> in<00:01:29.920> in<00:01:30.079> fact<00:01:30.640> this
gravitational effects in in fact this
gravitational effects in in fact this
dark<00:01:31.200> matter<00:01:31.960> dominates<00:01:32.759> the<00:01:32.920> gravitational
dark matter dominates the gravitational
dark matter dominates the gravitational
effects<00:01:33.840> in<00:01:33.960> the<00:01:34.040> universe<00:01:34.399> on<00:01:34.520> a<00:01:34.640> large<00:01:34.920> scale
effects in the universe on a large scale
effects in the universe on a large scale
and<00:01:35.520> I'll<00:01:35.640> be<00:01:35.759> telling<00:01:35.960> you<00:01:36.119> about<00:01:36.280> the
and I'll be telling you about the
and I'll be telling you about the
evidence<00:01:36.759> for<00:01:37.000> that<00:01:37.479> what<00:01:37.640> about<00:01:37.880> the<00:01:38.000> rest<00:01:38.159> of
evidence for that what about the rest of
evidence for that what about the rest of
the<00:01:38.520> pie<00:01:39.520> the<00:01:39.640> rest<00:01:39.759> of<00:01:39.880> the<00:01:40.040> pie<00:01:40.240> is<00:01:40.360> a<00:01:40.479> very
the pie the rest of the pie is a very
the pie the rest of the pie is a very
mysterious<00:01:41.200> substance<00:01:41.720> called<00:01:42.200> Dark<00:01:42.439> Energy
mysterious substance called Dark Energy
mysterious substance called Dark Energy
more<00:01:43.399> about<00:01:43.640> that<00:01:43.840> later<00:01:44.719> okay<00:01:45.200> so<00:01:45.399> for<00:01:45.600> now
more about that later okay so for now
more about that later okay so for now
let's<00:01:46.399> turn<00:01:46.759> to<00:01:46.920> the<00:01:47.079> evidence<00:01:47.640> for<00:01:47.920> dark
let's turn to the evidence for dark
let's turn to the evidence for dark
matter<00:01:48.759> in<00:01:48.920> these<00:01:49.159> galaxies<00:01:49.680> especially<00:01:49.960> in<00:01:50.040> a
matter in these galaxies especially in a
matter in these galaxies especially in a
spiral<00:01:50.560> galaxy<00:01:51.000> like<00:01:51.240> this<00:01:51.719> most<00:01:51.880> of<00:01:52.040> the<00:01:52.240> mass
spiral galaxy like this most of the mass
spiral galaxy like this most of the mass
of<00:01:52.799> the<00:01:53.000> stars<00:01:53.799> is<00:01:54.079> concentrated<00:01:54.719> in<00:01:54.799> the
of the stars is concentrated in the
of the stars is concentrated in the
middle<00:01:55.159> of<00:01:55.280> the<00:01:55.479> Galaxy<00:01:56.479> this<00:01:56.759> huge<00:01:57.320> mass<00:01:57.640> of
middle of the Galaxy this huge mass of
middle of the Galaxy this huge mass of
all<00:01:58.000> these<00:01:58.280> Stars<00:01:59.280> keeps
all these Stars keeps
all these Stars keeps
stars<00:02:01.000> in<00:02:01.240> circular<00:02:01.799> orbits<00:02:02.479> in<00:02:02.600> the<00:02:02.799> Galaxy
stars in circular orbits in the Galaxy
stars in circular orbits in the Galaxy
so<00:02:03.680> we<00:02:03.799> have<00:02:03.960> these<00:02:04.119> stars<00:02:04.439> going<00:02:04.680> around<00:02:04.880> in
so we have these stars going around in
so we have these stars going around in
circles<00:02:05.479> like<00:02:05.680> this<00:02:06.240> as<00:02:06.320> you<00:02:06.439> can<00:02:06.600> imagine
circles like this as you can imagine
circles like this as you can imagine
even<00:02:07.079> if<00:02:07.159> you<00:02:07.280> know<00:02:07.479> the<00:02:07.640> no<00:02:07.880> physics<00:02:08.200> this
even if you know the no physics this
even if you know the no physics this
should<00:02:08.440> be<00:02:08.599> intuitive<00:02:09.520> okay<00:02:10.160> that<00:02:10.840> stars<00:02:11.280> that
should be intuitive okay that stars that
should be intuitive okay that stars that
are<00:02:11.680> closer<00:02:12.360> to<00:02:12.520> the<00:02:12.680> mass<00:02:12.920> in<00:02:13.040> the<00:02:13.160> middle
are closer to the mass in the middle
are closer to the mass in the middle
will<00:02:13.959> be<00:02:14.160> rotating<00:02:14.760> at<00:02:14.879> a<00:02:15.040> higher<00:02:15.440> speed<00:02:16.160> than
will be rotating at a higher speed than
will be rotating at a higher speed than
those<00:02:16.680> that<00:02:16.800> are<00:02:17.040> far<00:02:17.319> further<00:02:17.640> out<00:02:17.959> here<00:02:18.720> okay
those that are far further out here okay
those that are far further out here okay
so<00:02:19.560> what<00:02:19.680> you<00:02:19.760> would<00:02:20.040> expect<00:02:20.560> is<00:02:20.680> that<00:02:20.800> if<00:02:20.920> you
so what you would expect is that if you
so what you would expect is that if you
measured<00:02:22.080> the<00:02:22.440> orbital<00:02:22.959> speed<00:02:23.360> of<00:02:23.519> the<00:02:23.800> stars
measured the orbital speed of the stars
measured the orbital speed of the stars
that<00:02:24.640> they<00:02:24.720> should<00:02:24.920> be<00:02:25.120> slower<00:02:25.680> on<00:02:25.800> the<00:02:25.959> edges
that they should be slower on the edges
that they should be slower on the edges
than<00:02:26.640> on<00:02:26.800> the<00:02:27.080> inside<00:02:28.080> in<00:02:28.239> other<00:02:28.400> words<00:02:28.680> if<00:02:28.800> we
than on the inside in other words if we
than on the inside in other words if we
measured<00:02:29.319> speed<00:02:29.840> as<00:02:29.920> a<00:02:30.000> function<00:02:30.239> of<00:02:30.400> distance
measured speed as a function of distance
measured speed as a function of distance
this<00:02:30.800> is<00:02:30.920> the<00:02:31.000> only<00:02:31.120> time<00:02:31.239> I'm<00:02:31.360> going<00:02:31.440> to<00:02:31.519> show
this is the only time I'm going to show
this is the only time I'm going to show
a<00:02:31.800> graph<00:02:32.360> okay<00:02:32.760> we<00:02:32.879> would<00:02:33.120> expect<00:02:33.800> that<00:02:34.040> it
a graph okay we would expect that it
a graph okay we would expect that it
goes<00:02:34.720> down<00:02:35.360> as<00:02:35.560> the<00:02:35.720> distance<00:02:36.080> increases<00:02:36.560> from
goes down as the distance increases from
goes down as the distance increases from
the<00:02:36.800> center<00:02:37.040> of<00:02:37.160> the<00:02:37.280> Galaxy<00:02:38.160> when<00:02:38.360> those
the center of the Galaxy when those
the center of the Galaxy when those
measurements<00:02:38.959> are<00:02:39.200> made<00:02:39.680> instead<00:02:40.040> what<00:02:40.159> we
measurements are made instead what we
measurements are made instead what we
find<00:02:40.879> is<00:02:41.040> that<00:02:41.159> the<00:02:41.280> speed<00:02:41.560> is<00:02:41.760> basically
find is that the speed is basically
find is that the speed is basically
constant<00:02:42.800> as<00:02:42.920> a<00:02:43.040> function<00:02:43.319> of<00:02:43.519> distance<00:02:44.360> if
constant as a function of distance if
constant as a function of distance if
it's<00:02:44.760> constant<00:02:45.239> that<00:02:45.319> means<00:02:45.560> that<00:02:45.720> the<00:02:45.879> stars
it's constant that means that the stars
it's constant that means that the stars
out<00:02:46.560> here<00:02:47.000> are<00:02:47.519> are<00:02:47.680> feeling<00:02:48.120> the
out here are are feeling the
out here are are feeling the
gravitational<00:02:49.000> effects<00:02:49.640> of<00:02:49.800> matter<00:02:50.120> that<00:02:50.280> we
gravitational effects of matter that we
gravitational effects of matter that we
do<00:02:50.599> not<00:02:50.879> see<00:02:51.840> in<00:02:52.040> fact<00:02:52.480> this<00:02:52.720> Galaxy<00:02:53.239> and<00:02:53.440> every
do not see in fact this Galaxy and every
do not see in fact this Galaxy and every
other<00:02:53.959> Galaxy<00:02:54.519> appears<00:02:54.920> to<00:02:55.080> be<00:02:55.440> embedded<00:02:56.440> in<00:02:56.560> a
other Galaxy appears to be embedded in a
other Galaxy appears to be embedded in a
cloud<00:02:57.519> of<00:02:57.720> this<00:02:57.959> invisible<00:02:58.959> dark<00:02:59.280> matter<00:03:00.040> and
cloud of this invisible dark matter and
cloud of this invisible dark matter and
this<00:03:00.319> cloud<00:03:00.560> of<00:03:00.720> matter<00:03:01.000> is<00:03:01.159> much<00:03:01.280> more
this cloud of matter is much more
this cloud of matter is much more
spherical<00:03:02.080> than<00:03:02.200> the<00:03:02.319> Galaxy<00:03:02.959> themselves<00:03:03.840> and
spherical than the Galaxy themselves and
spherical than the Galaxy themselves and
it<00:03:04.200> extends<00:03:04.760> over<00:03:04.959> a<00:03:05.120> much<00:03:05.640> W<00:03:06.000> wider<00:03:06.319> range
it extends over a much W wider range
it extends over a much W wider range
than<00:03:06.840> the<00:03:07.040> Galaxy<00:03:07.799> so<00:03:08.040> we<00:03:08.200> see<00:03:08.480> the<00:03:08.680> Galaxy<00:03:09.120> and
than the Galaxy so we see the Galaxy and
than the Galaxy so we see the Galaxy and
fixate<00:03:09.680> on<00:03:09.920> that<00:03:10.120> but<00:03:10.239> it's<00:03:10.440> actually<00:03:10.640> a<00:03:10.760> cloud
fixate on that but it's actually a cloud
fixate on that but it's actually a cloud
of<00:03:11.159> Dark<00:03:11.400> Matter<00:03:11.680> that's<00:03:11.920> dominating<00:03:12.720> the
of Dark Matter that's dominating the
of Dark Matter that's dominating the
structure<00:03:13.440> and<00:03:13.720> the<00:03:13.959> Dynamics<00:03:14.480> of<00:03:14.640> this
structure and the Dynamics of this
structure and the Dynamics of this
galaxy<00:03:16.040> galaxies<00:03:16.720> themselves<00:03:17.040> are<00:03:17.239> not
galaxy galaxies themselves are not
galaxy galaxies themselves are not
strewn<00:03:18.120> randomly<00:03:18.640> in<00:03:18.879> space<00:03:19.599> they<00:03:19.720> tend<00:03:19.920> to
strewn randomly in space they tend to
strewn randomly in space they tend to
Cluster<00:03:21.120> and<00:03:21.280> this<00:03:21.400> is<00:03:21.519> an<00:03:21.720> example<00:03:22.080> of<00:03:22.200> a<00:03:22.360> very
Cluster and this is an example of a very
Cluster and this is an example of a very
actually<00:03:22.879> famous<00:03:23.159> cluster<00:03:23.519> the<00:03:23.640> coma<00:03:24.000> cluster
actually famous cluster the coma cluster
actually famous cluster the coma cluster
and<00:03:24.760> there<00:03:24.879> are<00:03:25.200> thousands<00:03:25.599> of<00:03:25.879> galaxies<00:03:26.440> in
and there are thousands of galaxies in
and there are thousands of galaxies in
this<00:03:26.799> cluster<00:03:27.200> they're<00:03:27.400> the<00:03:27.599> white<00:03:28.400> uh<00:03:28.519> fuzzy
this cluster they're the white uh fuzzy
this cluster they're the white uh fuzzy
elliptical<00:03:29.799> things<00:03:30.080> here<00:03:30.560> so<00:03:30.799> these<00:03:31.000> Galaxy
elliptical things here so these Galaxy
elliptical things here so these Galaxy
clusters<00:03:31.799> we<00:03:31.920> take<00:03:32.040> a<00:03:32.200> snapshot<00:03:32.799> now<00:03:33.239> we<00:03:33.360> take
clusters we take a snapshot now we take
clusters we take a snapshot now we take
a<00:03:33.640> snapshot<00:03:34.120> in<00:03:34.200> a<00:03:34.360> decade<00:03:34.680> it'll<00:03:34.920> look
a snapshot in a decade it'll look
a snapshot in a decade it'll look
identical<00:03:36.000> but<00:03:36.319> these<00:03:36.519> galaxies<00:03:36.879> are
identical but these galaxies are
identical but these galaxies are
actually<00:03:37.319> moving<00:03:37.760> at<00:03:38.120> extremely<00:03:38.840> high<00:03:39.080> speeds
actually moving at extremely high speeds
actually moving at extremely high speeds
they're<00:03:40.000> moving<00:03:40.400> around<00:03:41.159> in<00:03:41.560> in<00:03:41.720> this
they're moving around in in this
they're moving around in in this
gravitational<00:03:43.280> potential<00:03:43.720> well<00:03:44.200> of<00:03:44.400> this
gravitational potential well of this
gravitational potential well of this
cluster<00:03:45.519> okay<00:03:45.720> so<00:03:45.840> all<00:03:46.000> these<00:03:46.159> galaxies<00:03:46.560> are
cluster okay so all these galaxies are
cluster okay so all these galaxies are
moving<00:03:47.280> we<00:03:47.360> can<00:03:47.560> measure<00:03:47.840> the<00:03:48.000> speeds<00:03:48.280> of
moving we can measure the speeds of
moving we can measure the speeds of
these<00:03:48.680> galaxies<00:03:49.280> the<00:03:49.560> their<00:03:49.840> orbital
these galaxies the their orbital
these galaxies the their orbital
velocities<00:03:51.200> and<00:03:51.360> figure<00:03:51.599> out<00:03:51.799> how<00:03:51.959> much<00:03:52.280> mass
velocities and figure out how much mass
velocities and figure out how much mass
is<00:03:52.799> in<00:03:53.000> this<00:03:53.159> cluster<00:03:53.959> and<00:03:54.159> again<00:03:54.439> what<00:03:54.560> we
is in this cluster and again what we
is in this cluster and again what we
find<00:03:55.319> is<00:03:55.480> that<00:03:55.599> there<00:03:55.720> is<00:03:56.000> much<00:03:56.319> more<00:03:56.720> mass
find is that there is much more mass
find is that there is much more mass
there<00:03:57.840> than<00:03:58.079> can<00:03:58.239> be<00:03:58.400> accounted<00:03:58.840> for<00:03:59.280> by<00:03:59.400> the
there than can be accounted for by the
there than can be accounted for by the
galaxies<00:04:00.200> that<00:04:00.319> we<00:04:00.480> see<00:04:01.239> or<00:04:01.599> if<00:04:01.680> we<00:04:01.799> look<00:04:01.920> in
galaxies that we see or if we look in
galaxies that we see or if we look in
other<00:04:02.280> parts<00:04:02.439> of<00:04:02.560> the<00:04:02.640> electromagnetic
other parts of the electromagnetic
other parts of the electromagnetic
spectrum<00:04:03.599> we<00:04:03.680> see<00:04:03.799> that<00:04:03.879> there's<00:04:04.040> a<00:04:04.120> lot<00:04:04.239> of
spectrum we see that there's a lot of
spectrum we see that there's a lot of
gas<00:04:04.799> in<00:04:04.920> this<00:04:05.079> cluster<00:04:05.480> as<00:04:05.599> well<00:04:06.079> but<00:04:06.239> that
gas in this cluster as well but that
gas in this cluster as well but that
cannot<00:04:06.720> account<00:04:06.959> for<00:04:07.200> the<00:04:07.319> mass<00:04:07.680> either<00:04:08.200> in
cannot account for the mass either in
cannot account for the mass either in
fact<00:04:08.519> there<00:04:08.720> appears<00:04:09.040> to<00:04:09.200> be<00:04:09.400> about<00:04:09.680> 10<00:04:10.079> times
fact there appears to be about 10 times
fact there appears to be about 10 times
as<00:04:10.519> much<00:04:10.840> mass<00:04:11.200> here<00:04:11.760> in<00:04:11.879> the<00:04:12.000> form<00:04:12.239> of<00:04:12.439> this
as much mass here in the form of this
as much mass here in the form of this
invisible<00:04:13.280> or<00:04:13.599> dark<00:04:13.920> matter<00:04:14.799> as<00:04:15.000> there<00:04:15.239> is<00:04:15.480> in
invisible or dark matter as there is in
invisible or dark matter as there is in
the<00:04:15.840> ordinary<00:04:16.759> matter<00:04:17.959> okay<00:04:18.959> it<00:04:19.040> would<00:04:19.199> be
the ordinary matter okay it would be
the ordinary matter okay it would be
nice<00:04:19.720> if<00:04:19.880> we<00:04:20.000> could<00:04:20.160> see<00:04:20.479> this<00:04:20.720> dark<00:04:20.959> matter<00:04:21.199> a
nice if we could see this dark matter a
nice if we could see this dark matter a
little<00:04:21.479> bit<00:04:21.600> more<00:04:21.840> directly<00:04:22.479> I'm<00:04:22.600> just
little bit more directly I'm just
little bit more directly I'm just
putting<00:04:22.919> this<00:04:23.160> big<00:04:23.360> blue<00:04:23.759> blob<00:04:24.160> on<00:04:24.320> there<00:04:24.560> okay
putting this big blue blob on there okay
putting this big blue blob on there okay
to<00:04:24.840> try<00:04:25.000> to<00:04:25.360> remind<00:04:25.680> you<00:04:25.840> that<00:04:26.000> it's<00:04:26.320> there<00:04:27.000> can
to try to remind you that it's there can
to try to remind you that it's there can
we<00:04:27.320> see<00:04:27.520> it<00:04:27.639> more<00:04:27.840> visually<00:04:28.320> yes<00:04:28.479> we<00:04:28.639> can<00:04:29.240> and
we see it more visually yes we can and
we see it more visually yes we can and
so<00:04:29.680> let<00:04:29.759> me<00:04:29.880> lead<00:04:30.080> you<00:04:30.479> through<00:04:30.680> how<00:04:30.840> we<00:04:30.919> can<00:04:31.080> do
so let me lead you through how we can do
so let me lead you through how we can do
this<00:04:31.880> so<00:04:32.240> here<00:04:32.360> is<00:04:32.639> an<00:04:32.800> observer<00:04:33.440> it<00:04:33.560> could<00:04:33.680> be
this so here is an observer it could be
this so here is an observer it could be
an<00:04:33.919> eye<00:04:34.120> it<00:04:34.199> could<00:04:34.320> be<00:04:34.400> a<00:04:34.520> telescope<00:04:35.320> and
an eye it could be a telescope and
an eye it could be a telescope and
suppose<00:04:35.680> there's<00:04:35.880> a<00:04:36.039> Galaxy<00:04:36.440> out<00:04:36.600> here<00:04:36.720> in<00:04:36.840> the
suppose there's a Galaxy out here in the
suppose there's a Galaxy out here in the
universe<00:04:37.600> how<00:04:37.720> do<00:04:37.800> we<00:04:37.919> see<00:04:38.199> that<00:04:38.400> Galaxy<00:04:39.320> a<00:04:39.520> ray
universe how do we see that Galaxy a ray
universe how do we see that Galaxy a ray
of<00:04:39.919> light<00:04:40.280> leaves<00:04:40.600> the<00:04:40.759> Galaxy<00:04:41.400> and<00:04:41.560> travels
of light leaves the Galaxy and travels
of light leaves the Galaxy and travels
through<00:04:42.120> the<00:04:42.240> universe<00:04:42.680> for<00:04:42.880> perhaps
through the universe for perhaps
through the universe for perhaps
billions<00:04:43.840> of<00:04:44.080> years<00:04:44.440> before<00:04:44.639> it<00:04:44.880> enters<00:04:45.639> the
billions of years before it enters the
billions of years before it enters the
telescope<00:04:46.639> or<00:04:46.840> your<00:04:47.080> eye<00:04:47.759> now<00:04:47.960> how<00:04:48.080> do<00:04:48.280> we
telescope or your eye now how do we
telescope or your eye now how do we
deduce<00:04:49.080> where<00:04:49.280> the<00:04:49.560> Galaxy<00:04:50.080> is<00:04:50.680> well<00:04:50.840> we
deduce where the Galaxy is well we
deduce where the Galaxy is well we
deduce<00:04:51.360> it<00:04:51.560> by<00:04:51.680> the<00:04:51.880> direction<00:04:52.280> that<00:04:52.440> the<00:04:52.560> ray
deduce it by the direction that the ray
deduce it by the direction that the ray
is<00:04:53.000> traveling<00:04:53.600> as<00:04:53.720> it<00:04:53.840> enters<00:04:54.160> our<00:04:54.360> eye<00:04:55.000> right
is traveling as it enters our eye right
is traveling as it enters our eye right
we<00:04:55.440> say<00:04:55.800> the<00:04:56.120> ray<00:04:56.280> of<00:04:56.440> light<00:04:56.639> came<00:04:56.840> this<00:04:57.000> way
we say the ray of light came this way
we say the ray of light came this way
the<00:04:57.520> Galaxy<00:04:57.919> must<00:04:58.160> be<00:04:58.400> there<00:04:59.120> okay<00:04:59.759> now
the Galaxy must be there okay now
the Galaxy must be there okay now
suppose<00:05:00.919> I<00:05:01.039> put<00:05:01.199> in<00:05:01.320> the<00:05:01.400> middle<00:05:01.919> a<00:05:02.080> cluster<00:05:02.479> of
suppose I put in the middle a cluster of
suppose I put in the middle a cluster of
galaxies<00:05:03.120> and<00:05:03.280> don't<00:05:03.479> forget<00:05:03.800> the<00:05:03.960> dark
galaxies and don't forget the dark
galaxies and don't forget the dark
matter<00:05:05.080> okay<00:05:05.639> now<00:05:06.000> if<00:05:06.120> we<00:05:06.320> consider<00:05:06.720> a
matter okay now if we consider a
matter okay now if we consider a
different<00:05:07.240> ray<00:05:07.440> of<00:05:07.639> light<00:05:07.880> one<00:05:08.080> going<00:05:08.320> off
different ray of light one going off
different ray of light one going off
like<00:05:08.840> this<00:05:09.440> we<00:05:09.600> now<00:05:09.919> need<00:05:10.039> to<00:05:10.199> take<00:05:10.400> into
like this we now need to take into
like this we now need to take into
account<00:05:11.199> what<00:05:11.400> Einstein<00:05:11.919> predicted<00:05:12.320> when<00:05:12.440> he
account what Einstein predicted when he
account what Einstein predicted when he
developed<00:05:12.960> general<00:05:13.280> relativity<00:05:14.240> and<00:05:14.440> that
developed general relativity and that
developed general relativity and that
was<00:05:14.919> that<00:05:15.280> the<00:05:15.520> gravitational<00:05:16.280> field<00:05:16.840> due<00:05:17.039> to
was that the gravitational field due to
was that the gravitational field due to
mass<00:05:18.319> will<00:05:18.639> deflect<00:05:19.120> not<00:05:19.280> only<00:05:19.520> the
mass will deflect not only the
mass will deflect not only the
trajectory<00:05:20.199> of<00:05:20.440> particles<00:05:21.319> but<00:05:21.479> will<00:05:22.319> deflect
trajectory of particles but will deflect
trajectory of particles but will deflect
light<00:05:23.800> itself<00:05:24.639> so<00:05:24.840> this<00:05:25.039> light<00:05:25.280> Ray<00:05:25.520> will<00:05:25.680> not
light itself so this light Ray will not
light itself so this light Ray will not
continue<00:05:26.240> in<00:05:26.360> a<00:05:26.479> straight<00:05:26.840> line<00:05:27.360> but<00:05:27.520> would
continue in a straight line but would
continue in a straight line but would
rather<00:05:28.280> Bend<00:05:28.720> and<00:05:28.840> could<00:05:29.000> end<00:05:29.160> up<00:05:29.280> going<00:05:29.680> into
rather Bend and could end up going into
rather Bend and could end up going into
our<00:05:30.479> eye<00:05:31.479> where<00:05:31.759> will<00:05:32.039> this<00:05:32.280> Observer<00:05:32.919> see<00:05:33.280> the
our eye where will this Observer see the
our eye where will this Observer see the
Galaxy<00:05:34.840> you<00:05:34.960> can
Galaxy you can
Galaxy you can
respond<00:05:36.800> up<00:05:37.240> right<00:05:37.759> we<00:05:37.960> extrapolate
respond up right we extrapolate
respond up right we extrapolate
backwards<00:05:38.960> and<00:05:39.120> say<00:05:39.400> the<00:05:39.560> Galaxy<00:05:40.000> is<00:05:40.160> up<00:05:40.400> here
backwards and say the Galaxy is up here
backwards and say the Galaxy is up here
is<00:05:41.360> there<00:05:41.520> any<00:05:41.720> other<00:05:42.000> ray<00:05:42.160> of<00:05:42.319> light<00:05:42.520> that
is there any other ray of light that
is there any other ray of light that
could<00:05:42.759> make<00:05:42.919> it<00:05:43.039> into<00:05:43.199> the<00:05:43.360> observer's<00:05:43.840> eye
could make it into the observer's eye
could make it into the observer's eye
from<00:05:44.280> that<00:05:44.960> Galaxy<00:05:45.960> yes<00:05:46.280> great<00:05:46.520> I<00:05:46.600> see<00:05:46.800> people
from that Galaxy yes great I see people
from that Galaxy yes great I see people
going<00:05:47.520> down<00:05:47.840> like<00:05:48.080> this<00:05:48.560> so<00:05:48.720> a<00:05:48.880> ray<00:05:49.039> of<00:05:49.160> light
going down like this so a ray of light
going down like this so a ray of light
could<00:05:49.520> go<00:05:49.720> down<00:05:50.039> be<00:05:50.240> bent<00:05:50.880> up<00:05:51.039> into<00:05:51.280> the
could go down be bent up into the
could go down be bent up into the
observer's<00:05:51.919> eye<00:05:52.360> and<00:05:52.479> the<00:05:52.560> Observer<00:05:52.919> sees<00:05:53.240> a
observer's eye and the Observer sees a
observer's eye and the Observer sees a
ray<00:05:53.560> of<00:05:53.720> light<00:05:53.960> here<00:05:54.680> now<00:05:54.880> take<00:05:55.120> into<00:05:55.360> account
ray of light here now take into account
ray of light here now take into account
the<00:05:55.800> fact<00:05:55.960> that<00:05:56.080> we<00:05:56.199> live<00:05:56.360> in<00:05:56.479> a
the fact that we live in a
the fact that we live in a
three-dimensional<00:05:57.600> Universe<00:05:58.440> okay
three-dimensional Universe okay
three-dimensional Universe okay
threedimensional<00:05:59.560> space<00:06:00.080> are<00:06:00.240> there<00:06:00.440> any
threedimensional space are there any
threedimensional space are there any
other<00:06:00.880> rays<00:06:01.160> of<00:06:01.360> light<00:06:01.720> that<00:06:01.840> could<00:06:02.000> make<00:06:02.120> it
other rays of light that could make it
other rays of light that could make it
into<00:06:02.479> the<00:06:02.759> eye<00:06:03.759> yes<00:06:04.199> the<00:06:04.639> Rays<00:06:04.919> would<00:06:05.120> lie<00:06:05.319> on<00:06:05.560> a
into the eye yes the Rays would lie on a
into the eye yes the Rays would lie on a
I<00:06:06.560> like<00:06:06.680> to<00:06:06.800> see<00:06:07.160> yeah<00:06:07.319> on<00:06:07.639> a<00:06:08.000> a<00:06:08.160> cone<00:06:08.720> so
I like to see yeah on a a cone so
I like to see yeah on a a cone so
there's<00:06:09.039> a<00:06:09.160> whole<00:06:09.440> ray<00:06:09.639> of<00:06:09.840> light<00:06:10.400> rays<00:06:10.599> of
there's a whole ray of light rays of
there's a whole ray of light rays of
light<00:06:11.000> on<00:06:11.120> a<00:06:11.280> cone<00:06:11.919> that<00:06:12.039> will<00:06:12.199> all<00:06:12.440> be<00:06:12.639> bent<00:06:13.160> by
light on a cone that will all be bent by
light on a cone that will all be bent by
that<00:06:13.560> cluster<00:06:14.120> and<00:06:14.280> make<00:06:14.479> it<00:06:14.599> into<00:06:14.800> the
that cluster and make it into the
that cluster and make it into the
observer's<00:06:15.599> eye<00:06:16.160> if<00:06:16.319> there's<00:06:16.800> a<00:06:16.960> cone<00:06:17.240> of
observer's eye if there's a cone of
observer's eye if there's a cone of
light<00:06:17.639> coming<00:06:17.880> into<00:06:18.160> my<00:06:18.400> eye<00:06:18.960> what<00:06:19.080> do<00:06:19.240> I
light coming into my eye what do I
light coming into my eye what do I
see<00:06:21.039> a<00:06:21.199> circle<00:06:21.720> a<00:06:21.919> ring<00:06:22.440> it's<00:06:22.639> called<00:06:22.840> an
see a circle a ring it's called an
see a circle a ring it's called an
Einstein<00:06:23.479> ring<00:06:23.919> Einstein<00:06:24.440> predicted<00:06:24.919> that
Einstein ring Einstein predicted that
Einstein ring Einstein predicted that
okay<00:06:25.919> now<00:06:26.160> it'll<00:06:26.400> only<00:06:26.639> be<00:06:26.800> a<00:06:27.000> perfect<00:06:27.400> ring<00:06:28.160> if
okay now it'll only be a perfect ring if
okay now it'll only be a perfect ring if
the<00:06:28.639> source<00:06:29.560> the<00:06:29.919> deflector<00:06:30.919> and<00:06:31.520> the<00:06:31.720> eyeball
the source the deflector and the eyeball
the source the deflector and the eyeball
in<00:06:32.400> this<00:06:32.599> case<00:06:32.960> are<00:06:33.160> all<00:06:33.319> in<00:06:33.440> a<00:06:33.599> perfectly
in this case are all in a perfectly
in this case are all in a perfectly
straight<00:06:34.319> line<00:06:35.160> if<00:06:35.280> they're<00:06:35.560> slightly<00:06:36.000> skewed
straight line if they're slightly skewed
straight line if they're slightly skewed
we'll<00:06:36.639> see<00:06:36.800> a<00:06:36.919> different<00:06:37.199> image<00:06:38.000> now<00:06:38.120> you<00:06:38.240> can
we'll see a different image now you can
we'll see a different image now you can
do<00:06:38.960> an<00:06:39.160> experiment<00:06:39.759> tonight<00:06:40.160> over<00:06:40.319> the
do an experiment tonight over the
do an experiment tonight over the
reception<00:06:41.400> okay<00:06:41.880> um<00:06:42.000> to<00:06:42.120> figure<00:06:42.319> out<00:06:42.479> what
reception okay um to figure out what
reception okay um to figure out what
that<00:06:42.720> image<00:06:42.919> will<00:06:43.120> look<00:06:43.360> like<00:06:44.160> uh<00:06:44.319> because<00:06:44.479> it
that image will look like uh because it
that image will look like uh because it
turns<00:06:44.840> out<00:06:45.039> that<00:06:45.160> there<00:06:45.319> is<00:06:45.919> a<00:06:46.080> kind<00:06:46.240> of<00:06:46.479> lens
turns out that there is a kind of lens
turns out that there is a kind of lens
that<00:06:47.240> we<00:06:47.360> can<00:06:47.599> devise<00:06:48.599> that<00:06:48.960> has<00:06:49.120> the<00:06:49.319> right
that we can devise that has the right
that we can devise that has the right
shape<00:06:50.039> to<00:06:50.280> produce<00:06:51.000> this<00:06:51.160> kind<00:06:51.319> of<00:06:51.560> effect<00:06:51.840> we
shape to produce this kind of effect we
shape to produce this kind of effect we
call<00:06:52.160> this<00:06:52.319> gravitational<00:06:52.960> lensing<00:06:53.960> and<00:06:54.120> so
call this gravitational lensing and so
call this gravitational lensing and so
this<00:06:54.919> is<00:06:55.080> your<00:06:55.440> instrument<00:06:56.560> okay<00:06:57.560> but<00:06:58.080> ignore
this is your instrument okay but ignore
this is your instrument okay but ignore
the<00:06:59.479> top<00:06:59.759> part<00:07:00.479> it's<00:07:00.720> the<00:07:00.879> base<00:07:01.280> that<00:07:01.400> I<00:07:01.479> want
the top part it's the base that I want
the top part it's the base that I want
you<00:07:01.759> to<00:07:02.120> concentrate<00:07:03.120> okay<00:07:03.520> so<00:07:03.720> actually<00:07:03.919> at
you to concentrate okay so actually at
you to concentrate okay so actually at
home<00:07:04.360> whenever<00:07:04.599> we<00:07:04.759> break<00:07:04.960> a<00:07:05.199> wine<00:07:05.440> glass<00:07:05.680> I
home whenever we break a wine glass I
home whenever we break a wine glass I
save<00:07:06.039> the<00:07:06.160> bottom<00:07:06.759> take<00:07:06.879> it<00:07:07.000> over<00:07:07.120> to<00:07:07.199> the
save the bottom take it over to the
save the bottom take it over to the
Machine<00:07:07.560> Shop<00:07:07.879> we<00:07:08.000> shave<00:07:08.240> it<00:07:08.400> off<00:07:08.800> and<00:07:08.919> I<00:07:09.080> have
Machine Shop we shave it off and I have
Machine Shop we shave it off and I have
a<00:07:09.360> little<00:07:09.720> gravitational<00:07:10.360> lens<00:07:10.919> okay<00:07:11.039> so<00:07:11.160> it's
a little gravitational lens okay so it's
a little gravitational lens okay so it's
got<00:07:11.440> the<00:07:11.560> right<00:07:11.720> shape<00:07:12.039> to<00:07:12.240> produce<00:07:12.520> the
got the right shape to produce the
got the right shape to produce the
lensing<00:07:13.520> and<00:07:13.639> so<00:07:13.879> the<00:07:14.000> next<00:07:14.160> thing<00:07:14.280> you<00:07:14.360> need
lensing and so the next thing you need
lensing and so the next thing you need
to<00:07:14.599> do<00:07:14.720> in<00:07:14.840> your<00:07:15.039> experiment<00:07:15.960> is<00:07:16.319> grab<00:07:16.520> a
to do in your experiment is grab a
to do in your experiment is grab a
napkin<00:07:17.240> I<00:07:17.360> grabbed<00:07:17.599> a<00:07:17.680> piece<00:07:17.800> of<00:07:17.879> graph<00:07:18.160> paper
napkin I grabbed a piece of graph paper
napkin I grabbed a piece of graph paper
I'm<00:07:18.520> a<00:07:18.639> physicist<00:07:19.160> so<00:07:19.919> uh<00:07:20.360> a<00:07:20.560> napkin<00:07:21.479> draw<00:07:21.919> a
I'm a physicist so uh a napkin draw a
I'm a physicist so uh a napkin draw a
little<00:07:22.240> model<00:07:22.639> galaxy<00:07:23.000> in<00:07:23.080> the<00:07:23.199> middle<00:07:23.960> and
little model galaxy in the middle and
little model galaxy in the middle and
now<00:07:24.360> put<00:07:24.560> the<00:07:24.680> lens<00:07:25.080> over<00:07:25.319> the<00:07:25.520> Galaxy<00:07:26.160> and
now put the lens over the Galaxy and
now put the lens over the Galaxy and
what<00:07:26.440> you'll<00:07:26.720> find<00:07:27.199> is<00:07:27.400> that<00:07:27.599> you<00:07:27.720> will<00:07:27.840> see<00:07:28.080> a
what you'll find is that you will see a
what you'll find is that you will see a
ring<00:07:28.520> an<00:07:28.720> Einstein<00:07:29.120> ring
ring an Einstein ring
ring an Einstein ring
now<00:07:30.000> move<00:07:30.360> the<00:07:30.560> base<00:07:31.000> off<00:07:31.160> to<00:07:31.360> the<00:07:31.599> side<00:07:32.479> and
now move the base off to the side and
now move the base off to the side and
the<00:07:32.919> ring<00:07:33.400> will<00:07:33.599> split<00:07:33.919> up<00:07:34.199> into<00:07:34.440> arcs<00:07:35.400> okay
the ring will split up into arcs okay
the ring will split up into arcs okay
and<00:07:35.879> you<00:07:36.000> can<00:07:36.120> put<00:07:36.240> it<00:07:36.400> on<00:07:36.599> top<00:07:36.759> of<00:07:36.919> any<00:07:37.080> image
and you can put it on top of any image
and you can put it on top of any image
on<00:07:37.520> the<00:07:37.599> graph<00:07:37.879> paper<00:07:38.080> you<00:07:38.160> can<00:07:38.280> see<00:07:38.400> how<00:07:38.560> all
on the graph paper you can see how all
on the graph paper you can see how all
the<00:07:38.960> the<00:07:39.080> lines<00:07:39.319> on<00:07:39.440> the<00:07:39.560> graph<00:07:39.800> paper<00:07:40.039> have
the the lines on the graph paper have
the the lines on the graph paper have
been<00:07:40.360> distorted<00:07:40.879> and<00:07:41.080> again<00:07:41.560> this<00:07:41.639> is<00:07:41.879> a<00:07:42.639> an
been distorted and again this is a an
been distorted and again this is a an
kind<00:07:43.000> of<00:07:43.080> an<00:07:43.240> accurate<00:07:43.560> model<00:07:43.879> of<00:07:44.000> what
kind of an accurate model of what
kind of an accurate model of what
happens<00:07:44.400> with<00:07:44.520> the<00:07:44.639> gravitational<00:07:45.240> lensing
happens with the gravitational lensing
happens with the gravitational lensing
okay<00:07:46.560> so<00:07:47.120> the<00:07:47.240> question<00:07:47.520> is<00:07:47.680> do<00:07:47.840> we<00:07:47.960> see<00:07:48.199> this
okay so the question is do we see this
okay so the question is do we see this
in<00:07:48.520> the<00:07:48.720> sky<00:07:49.400> do<00:07:49.520> we<00:07:49.680> see<00:07:49.960> arcs<00:07:50.520> in<00:07:50.680> the<00:07:50.879> sky
in the sky do we see arcs in the sky
in the sky do we see arcs in the sky
when<00:07:51.319> we<00:07:51.440> look<00:07:51.599> at<00:07:51.840> say<00:07:52.000> a<00:07:52.120> cluster<00:07:52.479> of
when we look at say a cluster of
when we look at say a cluster of
galaxies<00:07:53.479> and<00:07:53.599> the<00:07:53.759> answer<00:07:54.039> is<00:07:54.520> yes<00:07:55.120> and<00:07:55.199> so
galaxies and the answer is yes and so
galaxies and the answer is yes and so
here's<00:07:55.720> an<00:07:55.919> image<00:07:56.400> from<00:07:56.520> the<00:07:56.639> Hubble<00:07:56.960> Space
here's an image from the Hubble Space
here's an image from the Hubble Space
Telescope<00:07:57.680> many<00:07:57.840> of<00:07:57.919> the<00:07:58.000> images<00:07:58.280> you<00:07:58.400> were
Telescope many of the images you were
Telescope many of the images you were
seeing<00:07:59.319> earlier<00:07:59.720> from<00:07:59.840> the<00:08:00.000> Hubble<00:08:00.319> Space
seeing earlier from the Hubble Space
seeing earlier from the Hubble Space
Telescope<00:08:01.319> well<00:08:01.479> first<00:08:01.680> of<00:08:01.800> all<00:08:02.120> the<00:08:02.319> golden
Telescope well first of all the golden
Telescope well first of all the golden
shaped<00:08:03.280> galaxies<00:08:04.120> those<00:08:04.280> are<00:08:04.440> the<00:08:04.599> galaxies
shaped galaxies those are the galaxies
shaped galaxies those are the galaxies
in<00:08:05.240> the<00:08:05.440> cluster<00:08:06.240> they're<00:08:06.440> the<00:08:06.560> ones<00:08:06.800> that<00:08:06.919> are
in the cluster they're the ones that are
in the cluster they're the ones that are
embedded<00:08:08.080> in<00:08:08.360> that<00:08:08.680> sea<00:08:09.039> of<00:08:09.199> dark<00:08:09.479> matter<00:08:10.080> that
embedded in that sea of dark matter that
embedded in that sea of dark matter that
are<00:08:10.360> causing<00:08:10.720> the<00:08:10.879> bending<00:08:11.240> of<00:08:11.400> the<00:08:11.560> light<00:08:12.080> to
are causing the bending of the light to
are causing the bending of the light to
cause<00:08:12.560> these<00:08:12.840> optical<00:08:13.240> illusions<00:08:13.720> or<00:08:13.879> mirages
cause these optical illusions or mirages
cause these optical illusions or mirages
practically<00:08:15.360> of<00:08:15.520> the<00:08:15.680> background<00:08:16.240> galaxies
practically of the background galaxies
practically of the background galaxies
so<00:08:17.199> the<00:08:17.360> streaks<00:08:17.879> that<00:08:18.039> you<00:08:18.159> see<00:08:18.840> all<00:08:19.039> these
so the streaks that you see all these
so the streaks that you see all these
streaks<00:08:20.080> are<00:08:20.400> actually<00:08:20.840> distorted<00:08:21.479> images<00:08:21.879> of
streaks are actually distorted images of
streaks are actually distorted images of
galaxies<00:08:22.479> that<00:08:22.560> are<00:08:22.720> much<00:08:22.879> further<00:08:23.319> away<00:08:24.120> so
galaxies that are much further away so
galaxies that are much further away so
what<00:08:24.400> we<00:08:24.520> can<00:08:24.680> do<00:08:24.919> then<00:08:25.319> is<00:08:26.319> based<00:08:26.599> on<00:08:26.840> how<00:08:27.000> much
what we can do then is based on how much
what we can do then is based on how much
Distortion<00:08:28.000> we<00:08:28.120> see<00:08:28.319> in<00:08:28.479> those<00:08:28.680> images<00:08:29.319> we<00:08:29.440> can
Distortion we see in those images we can
Distortion we see in those images we can
calculate<00:08:30.240> how<00:08:30.440> much<00:08:30.840> mass<00:08:31.520> there<00:08:31.680> must<00:08:31.919> be<00:08:32.080> in
calculate how much mass there must be in
calculate how much mass there must be in
this<00:08:32.440> cluster<00:08:33.200> and<00:08:33.320> it's<00:08:33.440> an<00:08:33.640> enormous<00:08:34.159> amount
this cluster and it's an enormous amount
this cluster and it's an enormous amount
of<00:08:34.680> mass<00:08:35.279> and<00:08:35.440> also<00:08:35.680> you<00:08:35.760> can<00:08:35.919> tell<00:08:36.200> by<00:08:36.440> eye<00:08:36.800> by
of mass and also you can tell by eye by
of mass and also you can tell by eye by
looking<00:08:37.240> at<00:08:37.479> this<00:08:37.919> that<00:08:38.159> these<00:08:38.440> arcs<00:08:38.839> are<00:08:39.039> not
looking at this that these arcs are not
looking at this that these arcs are not
centered<00:08:39.719> on<00:08:40.000> individual<00:08:40.800> galaxies<00:08:41.640> they<00:08:41.760> are
centered on individual galaxies they are
centered on individual galaxies they are
centered<00:08:42.320> on<00:08:42.560> some<00:08:43.479> more<00:08:43.919> ma<00:08:44.240> uh<00:08:44.399> spread<00:08:44.720> out
centered on some more ma uh spread out
centered on some more ma uh spread out
structure<00:08:46.040> and<00:08:46.200> that<00:08:46.360> is<00:08:46.800> the<00:08:47.200> dark<00:08:47.519> matter
structure and that is the dark matter
structure and that is the dark matter
that<00:08:48.080> is<00:08:48.200> being<00:08:48.800> that<00:08:48.920> is<00:08:49.240> um<00:08:49.360> in<00:08:49.560> which<00:08:49.959> the
that is being that is um in which the
that is being that is um in which the
cluster<00:08:50.519> is<00:08:50.720> embedded<00:08:51.640> okay<00:08:52.080> so<00:08:52.240> this<00:08:52.320> is<00:08:52.480> the
cluster is embedded okay so this is the
cluster is embedded okay so this is the
closest<00:08:52.920> you<00:08:53.000> can<00:08:53.160> get<00:08:53.320> to<00:08:53.440> kind<00:08:53.560> of<00:08:53.680> seeing<00:08:54.240> at
closest you can get to kind of seeing at
closest you can get to kind of seeing at
least<00:08:54.560> the<00:08:54.720> effects<00:08:55.000> of<00:08:55.120> the<00:08:55.279> dark<00:08:55.480> matter
least the effects of the dark matter
least the effects of the dark matter
with<00:08:56.120> your<00:08:56.320> naked<00:08:56.839> eye<00:08:57.839> okay<00:08:58.000> so<00:08:58.200> a<00:08:58.399> quick
with your naked eye okay so a quick
with your naked eye okay so a quick
review<00:08:59.040> then<00:08:59.480> okay<00:08:59.600> to<00:08:59.720> see<00:08:59.920> that<00:09:00.040> you're
review then okay to see that you're
review then okay to see that you're
following<00:09:00.800> so<00:09:01.000> the<00:09:01.160> evidence<00:09:01.600> that<00:09:01.720> we<00:09:01.920> have
following so the evidence that we have
following so the evidence that we have
that<00:09:02.240> a<00:09:02.360> quarter<00:09:02.640> of<00:09:02.720> the<00:09:02.839> universe<00:09:03.519> is<00:09:03.720> dark
that a quarter of the universe is dark
that a quarter of the universe is dark
matter<00:09:04.240> this<00:09:04.480> gravitationally<00:09:05.160> attracting
matter this gravitationally attracting
matter this gravitationally attracting
stuff<00:09:06.560> is<00:09:06.760> that<00:09:07.000> galaxies<00:09:08.000> the<00:09:08.160> speeds<00:09:08.600> with
stuff is that galaxies the speeds with
stuff is that galaxies the speeds with
which<00:09:09.000> stars<00:09:09.720> orbit<00:09:10.079> in<00:09:10.240> galaxies<00:09:10.640> is<00:09:10.880> much
which stars orbit in galaxies is much
which stars orbit in galaxies is much
too<00:09:11.360> large<00:09:11.760> it<00:09:11.880> must<00:09:12.079> be<00:09:12.200> embedded<00:09:12.600> in<00:09:12.760> Dark
too large it must be embedded in Dark
too large it must be embedded in Dark
Matter<00:09:13.720> the<00:09:13.880> speed<00:09:14.240> with<00:09:14.399> which<00:09:14.680> galaxies
Matter the speed with which galaxies
Matter the speed with which galaxies
within<00:09:15.560> clusters<00:09:16.000> are<00:09:16.200> orbiting<00:09:16.720> is<00:09:16.880> much<00:09:17.079> too
within clusters are orbiting is much too
within clusters are orbiting is much too
large<00:09:17.519> it<00:09:17.640> must<00:09:17.800> be<00:09:17.959> embedded<00:09:18.399> in<00:09:18.600> dark<00:09:18.880> matter
large it must be embedded in dark matter
large it must be embedded in dark matter
and<00:09:19.760> we<00:09:19.880> see<00:09:20.160> these<00:09:20.399> gravitational<00:09:21.000> lensing
and we see these gravitational lensing
and we see these gravitational lensing
effects<00:09:21.880> these<00:09:22.240> distortions<00:09:23.240> that<00:09:23.440> say<00:09:23.720> that
effects these distortions that say that
effects these distortions that say that
again<00:09:24.440> clusters<00:09:24.880> are<00:09:25.040> embedded<00:09:25.399> in<00:09:25.560> dark
again clusters are embedded in dark
again clusters are embedded in dark
matter<00:09:26.760> okay<00:09:26.959> so<00:09:27.160> now<00:09:27.360> let's<00:09:27.560> turn<00:09:27.839> to<00:09:28.360> dark
matter okay so now let's turn to dark
matter okay so now let's turn to dark
energy
energy
energy
so<00:09:30.480> to<00:09:31.079> understand<00:09:31.440> the<00:09:31.600> evidence<00:09:31.920> for<00:09:32.120> Dark
so to understand the evidence for Dark
so to understand the evidence for Dark
Energy<00:09:33.000> we<00:09:33.120> need<00:09:33.240> to<00:09:33.440> discuss<00:09:33.839> something<00:09:34.160> that
Energy we need to discuss something that
Energy we need to discuss something that
Steven<00:09:34.680> Hawking<00:09:35.399> referred<00:09:35.800> to<00:09:36.120> in<00:09:36.240> the
Steven Hawking referred to in the
Steven Hawking referred to in the
previous<00:09:36.720> session<00:09:37.360> and<00:09:37.519> that<00:09:37.680> is<00:09:38.000> the<00:09:38.399> fact
previous session and that is the fact
previous session and that is the fact
that<00:09:39.079> space<00:09:39.720> itself<00:09:40.200> is<00:09:40.480> expanding<00:09:41.480> so<00:09:41.720> if<00:09:41.839> we
that space itself is expanding so if we
that space itself is expanding so if we
imagine<00:09:43.079> um<00:09:43.240> a<00:09:43.440> section<00:09:43.880> of<00:09:44.040> our<00:09:44.279> infinite
imagine um a section of our infinite
imagine um a section of our infinite
Universe<00:09:46.120> okay<00:09:46.480> and<00:09:46.600> so<00:09:46.920> I've<00:09:47.040> put<00:09:47.200> down<00:09:47.399> four
Universe okay and so I've put down four
Universe okay and so I've put down four
spiral<00:09:48.320> galaxies<00:09:49.079> okay<00:09:49.720> and<00:09:50.040> imagine<00:09:50.480> that
spiral galaxies okay and imagine that
spiral galaxies okay and imagine that
you<00:09:50.800> put<00:09:51.000> down<00:09:51.160> a<00:09:51.320> set<00:09:51.480> of<00:09:51.720> tape<00:09:52.120> measures<00:09:52.839> okay
you put down a set of tape measures okay
you put down a set of tape measures okay
so<00:09:53.160> every<00:09:53.360> line<00:09:53.560> on<00:09:53.760> here<00:09:54.200> corresponds<00:09:54.720> to<00:09:54.880> a
so every line on here corresponds to a
so every line on here corresponds to a
tape<00:09:55.279> measure<00:09:55.880> horizontal<00:09:56.320> or<00:09:56.440> vertical<00:09:56.839> for
tape measure horizontal or vertical for
tape measure horizontal or vertical for
measuring<00:09:58.000> where<00:09:58.320> things<00:09:58.640> are
measuring where things are
measuring where things are
if<00:10:00.000> you<00:10:00.120> could<00:10:00.320> do<00:10:00.640> this<00:10:01.160> what<00:10:01.320> you<00:10:01.399> would<00:10:01.680> find
if you could do this what you would find
if you could do this what you would find
that<00:10:02.360> with<00:10:02.600> each<00:10:02.920> passing<00:10:03.399> day<00:10:03.800> each<00:10:04.079> passing
that with each passing day each passing
that with each passing day each passing
year<00:10:05.079> each<00:10:05.320> passing<00:10:05.640> billions<00:10:06.000> of<00:10:06.200> years<00:10:06.680> okay
year each passing billions of years okay
year each passing billions of years okay
the<00:10:07.360> distance<00:10:07.760> between<00:10:08.160> galaxies<00:10:08.680> is<00:10:08.839> getting
the distance between galaxies is getting
the distance between galaxies is getting
greater<00:10:10.079> and<00:10:10.200> it's<00:10:10.399> not<00:10:10.640> because<00:10:11.040> galaxies
greater and it's not because galaxies
greater and it's not because galaxies
are<00:10:11.640> moving<00:10:12.160> away<00:10:12.399> from<00:10:12.600> each<00:10:12.760> other<00:10:13.240> through
are moving away from each other through
are moving away from each other through
space<00:10:14.720> they're<00:10:14.920> not<00:10:15.160> necessarily<00:10:15.560> moving
space they're not necessarily moving
space they're not necessarily moving
through<00:10:16.079> space<00:10:16.560> they<00:10:16.680> are<00:10:16.839> moving<00:10:17.320> away<00:10:17.560> from
through space they are moving away from
through space they are moving away from
each<00:10:18.000> other<00:10:18.320> because<00:10:18.720> space<00:10:19.240> itself<00:10:19.720> is
each other because space itself is
each other because space itself is
getting<00:10:20.360> bigger<00:10:21.279> okay<00:10:21.800> that's<00:10:22.040> what<00:10:22.160> the
getting bigger okay that's what the
getting bigger okay that's what the
expansion<00:10:22.880> of<00:10:23.480> the<00:10:23.640> universe<00:10:24.120> or<00:10:24.440> space<00:10:24.880> means
expansion of the universe or space means
expansion of the universe or space means
so<00:10:25.720> they're<00:10:25.880> moving<00:10:26.200> further<00:10:26.600> apart<00:10:27.560> now<00:10:28.040> um
so they're moving further apart now um
so they're moving further apart now um
and<00:10:29.600> what<00:10:29.760> Stephen<00:10:30.079> Hawking<00:10:30.399> mentioned<00:10:30.760> as
and what Stephen Hawking mentioned as
and what Stephen Hawking mentioned as
well<00:10:31.440> is<00:10:31.720> that<00:10:32.079> after<00:10:32.360> the<00:10:32.519> big<00:10:32.760> bang<00:10:33.959> space
well is that after the big bang space
well is that after the big bang space
expanded<00:10:35.440> at<00:10:35.560> a<00:10:35.720> very<00:10:36.040> rapid<00:10:36.360> rate<00:10:37.200> but
expanded at a very rapid rate but
expanded at a very rapid rate but
because<00:10:39.079> gravitationally<00:10:39.959> attracting
because gravitationally attracting
because gravitationally attracting
matter<00:10:41.040> is<00:10:41.279> embedded<00:10:41.839> in<00:10:42.120> this<00:10:42.399> space<00:10:43.160> it
matter is embedded in this space it
matter is embedded in this space it
tends<00:10:43.639> to<00:10:43.839> slow<00:10:44.360> down<00:10:44.639> the<00:10:44.839> expansion<00:10:45.320> of<00:10:45.480> the
tends to slow down the expansion of the
tends to slow down the expansion of the
space<00:10:46.480> okay<00:10:46.760> so<00:10:46.920> the<00:10:47.079> expansion<00:10:47.519> slows<00:10:48.079> down
space okay so the expansion slows down
space okay so the expansion slows down
with<00:10:48.639> time<00:10:49.560> so<00:10:49.880> in<00:10:50.000> the<00:10:50.240> last<00:10:50.639> century<00:10:51.600> okay
with time so in the last century okay
with time so in the last century okay
people<00:10:52.320> debated<00:10:53.160> about<00:10:53.480> whether<00:10:53.839> this
people debated about whether this
people debated about whether this
expansion<00:10:54.680> of<00:10:55.000> space<00:10:55.920> would<00:10:56.200> continue
expansion of space would continue
expansion of space would continue
forever<00:10:58.399> whether<00:10:58.680> it<00:10:58.800> would<00:10:59.160> slow<00:10:59.560> down<00:11:00.000> you
forever whether it would slow down you
forever whether it would slow down you
know<00:11:00.320> we'll<00:11:00.480> be<00:11:00.639> slowing<00:11:01.040> down<00:11:01.240> but<00:11:01.399> continue
know we'll be slowing down but continue
know we'll be slowing down but continue
forever<00:11:02.519> slow<00:11:03.360> down<00:11:04.360> and<00:11:04.720> stop<00:11:05.720> ASM<00:11:06.079> totically
forever slow down and stop ASM totically
forever slow down and stop ASM totically
stop<00:11:07.279> or<00:11:07.519> slow<00:11:07.959> down<00:11:08.560> stop<00:11:09.279> and<00:11:09.440> then<00:11:09.920> reverse
stop or slow down stop and then reverse
stop or slow down stop and then reverse
so<00:11:10.639> it<00:11:10.800> start<00:11:11.000> to<00:11:11.160> contract<00:11:11.680> again<00:11:12.480> so<00:11:12.920> a
so it start to contract again so a
so it start to contract again so a
little<00:11:13.240> over<00:11:13.440> a<00:11:13.600> decade<00:11:13.959> ago<00:11:14.680> two<00:11:15.680> um<00:11:16.000> groups
little over a decade ago two um groups
little over a decade ago two um groups
of<00:11:17.160> um<00:11:17.639> physicists<00:11:18.200> and<00:11:18.320> astronomers<00:11:19.279> set<00:11:19.560> out
of um physicists and astronomers set out
of um physicists and astronomers set out
to<00:11:20.079> measure<00:11:20.800> the<00:11:21.000> rate<00:11:21.320> at<00:11:21.560> which<00:11:21.800> the
to measure the rate at which the
to measure the rate at which the
expansion<00:11:22.519> of<00:11:22.720> space<00:11:23.120> was<00:11:23.279> slowing<00:11:23.839> down<00:11:24.800> okay
expansion of space was slowing down okay
expansion of space was slowing down okay
by<00:11:25.320> how<00:11:25.440> much<00:11:25.720> less<00:11:25.959> is<00:11:26.079> it<00:11:26.279> expanding<00:11:26.760> today
by how much less is it expanding today
by how much less is it expanding today
compared<00:11:27.600> to<00:11:28.160> say<00:11:28.399> a<00:11:28.519> couple<00:11:28.760> bill<00:11:29.240> years<00:11:29.480> ago
compared to say a couple bill years ago
compared to say a couple bill years ago
the<00:11:30.600> startling<00:11:31.639> answer<00:11:32.639> to<00:11:32.839> this<00:11:33.079> question
the startling answer to this question
the startling answer to this question
okay<00:11:33.920> from<00:11:34.079> these<00:11:34.279> experiments<00:11:35.279> was<00:11:35.560> that
okay from these experiments was that
okay from these experiments was that
space<00:11:36.519> is<00:11:36.800> expanding<00:11:37.800> at<00:11:37.920> a<00:11:38.200> faster<00:11:38.639> rate
space is expanding at a faster rate
space is expanding at a faster rate
today<00:11:39.480> than<00:11:39.639> it<00:11:39.839> was<00:11:40.120> a<00:11:40.200> few<00:11:40.399> billion<00:11:40.720> years
today than it was a few billion years
today than it was a few billion years
ago<00:11:41.959> okay<00:11:42.279> so<00:11:42.480> the<00:11:42.639> expansion<00:11:43.040> of<00:11:43.200> space<00:11:43.440> is
ago okay so the expansion of space is
ago okay so the expansion of space is
actually<00:11:44.200> speeding<00:11:44.800> up<00:11:45.800> this<00:11:45.920> was<00:11:46.040> a
actually speeding up this was a
actually speeding up this was a
completely<00:11:46.720> surprising<00:11:47.800> result<00:11:48.800> there<00:11:48.959> is<00:11:49.160> no
completely surprising result there is no
completely surprising result there is no
persuasive<00:11:50.880> theoretical<00:11:51.880> argument<00:11:52.360> for<00:11:52.600> why
persuasive theoretical argument for why
persuasive theoretical argument for why
this<00:11:53.000> should<00:11:53.240> happen<00:11:54.079> Okay<00:11:54.440> no<00:11:54.560> one<00:11:54.800> was
this should happen Okay no one was
this should happen Okay no one was
predicting<00:11:55.399> ahead<00:11:55.560> of<00:11:55.720> time<00:11:56.000> this<00:11:56.120> is<00:11:56.240> what's
predicting ahead of time this is what's
predicting ahead of time this is what's
going<00:11:56.600> to<00:11:56.720> be<00:11:56.839> found<00:11:57.160> it<00:11:57.240> was<00:11:57.399> the<00:11:57.600> opposite<00:11:57.959> of
going to be found it was the opposite of
going to be found it was the opposite of
what<00:11:58.279> was<00:11:58.519> expected
what was expected
what was expected
so<00:12:00.040> we<00:12:00.200> need<00:12:00.519> something<00:12:00.880> to<00:12:01.040> be<00:12:01.160> able<00:12:01.320> to
so we need something to be able to
so we need something to be able to
explain<00:12:02.200> that<00:12:02.800> now<00:12:02.920> it<00:12:03.040> turns<00:12:03.279> out<00:12:03.560> in<00:12:03.639> the
explain that now it turns out in the
explain that now it turns out in the
mathematics<00:12:04.959> you<00:12:05.120> can<00:12:05.320> put<00:12:05.440> it<00:12:05.639> in<00:12:06.000> as<00:12:06.079> a<00:12:06.279> term
mathematics you can put it in as a term
mathematics you can put it in as a term
that's<00:12:07.000> an<00:12:07.200> energy<00:12:07.760> but<00:12:07.839> it's<00:12:08.000> a<00:12:08.360> completely
that's an energy but it's a completely
that's an energy but it's a completely
different<00:12:09.079> type<00:12:09.240> of<00:12:09.360> energy<00:12:09.680> from<00:12:09.880> anything
different type of energy from anything
different type of energy from anything
we've<00:12:10.480> ever<00:12:10.639> seen<00:12:11.040> before<00:12:11.800> we<00:12:11.959> call<00:12:12.120> it<00:12:12.600> dark
we've ever seen before we call it dark
we've ever seen before we call it dark
energy<00:12:13.760> and<00:12:13.880> it<00:12:14.079> has<00:12:14.320> this<00:12:14.560> effect<00:12:14.839> of<00:12:15.040> causing
energy and it has this effect of causing
energy and it has this effect of causing
space<00:12:15.639> to<00:12:15.839> expand<00:12:16.600> but<00:12:16.760> we<00:12:16.880> don't<00:12:17.079> have<00:12:17.199> a<00:12:17.399> good
space to expand but we don't have a good
space to expand but we don't have a good
motivation<00:12:18.160> for<00:12:18.320> putting<00:12:18.560> it<00:12:18.680> in<00:12:18.839> there<00:12:19.000> at
motivation for putting it in there at
motivation for putting it in there at
this<00:12:19.320> point<00:12:19.720> okay<00:12:19.839> so<00:12:20.000> it's<00:12:20.199> really
this point okay so it's really
this point okay so it's really
unexplained<00:12:21.399> as<00:12:21.519> to<00:12:21.680> why<00:12:21.800> we<00:12:21.880> need<00:12:22.000> to<00:12:22.120> put<00:12:22.279> it
unexplained as to why we need to put it
unexplained as to why we need to put it
in<00:12:23.240> now<00:12:23.959> um<00:12:24.959> so<00:12:25.120> at<00:12:25.240> this<00:12:25.399> point<00:12:25.639> then<00:12:25.839> what<00:12:25.920> I
in now um so at this point then what I
in now um so at this point then what I
want<00:12:26.120> to<00:12:26.440> really<00:12:26.680> emphasize<00:12:27.160> to<00:12:27.320> you<00:12:27.800> is<00:12:27.920> that
want to really emphasize to you is that
want to really emphasize to you is that
first<00:12:28.240> of<00:12:28.360> all<00:12:28.480> dark<00:12:28.639> matter<00:12:28.920> and<00:12:29.040> dark<00:12:29.160> energy
first of all dark matter and dark energy
first of all dark matter and dark energy
are<00:12:29.600> completely<00:12:30.040> different<00:12:30.320> things<00:12:30.920> okay
are completely different things okay
are completely different things okay
there<00:12:31.480> really<00:12:31.639> two<00:12:31.880> Mysteries<00:12:32.279> out<00:12:32.480> there<00:12:32.639> as
there really two Mysteries out there as
there really two Mysteries out there as
to<00:12:33.279> what<00:12:33.480> what<00:12:33.680> makes<00:12:33.920> up<00:12:34.160> most<00:12:34.360> of<00:12:34.519> the
to what what makes up most of the
to what what makes up most of the
universe<00:12:35.399> and<00:12:35.560> they<00:12:35.800> have<00:12:36.360> very<00:12:36.600> different
universe and they have very different
universe and they have very different
effects<00:12:38.360> dark<00:12:39.040> matter<00:12:39.720> because<00:12:39.959> it
effects dark matter because it
effects dark matter because it
gravitationally<00:12:40.959> attracts<00:12:41.920> it<00:12:42.079> tends<00:12:42.360> to
gravitationally attracts it tends to
gravitationally attracts it tends to
encourage<00:12:43.680> the<00:12:43.880> growth<00:12:44.440> of<00:12:44.639> structure<00:12:45.600> okay
encourage the growth of structure okay
encourage the growth of structure okay
so<00:12:46.000> clusters<00:12:46.399> of<00:12:46.600> galaxies<00:12:47.040> will<00:12:47.240> tend<00:12:47.519> to
so clusters of galaxies will tend to
so clusters of galaxies will tend to
form<00:12:48.600> because<00:12:48.839> of<00:12:48.959> all<00:12:49.120> this<00:12:49.279> gravitational
form because of all this gravitational
form because of all this gravitational
attraction<00:12:50.920> dark<00:12:51.240> energy<00:12:51.720> on<00:12:51.880> the<00:12:52.000> other<00:12:52.240> hand
attraction dark energy on the other hand
attraction dark energy on the other hand
is<00:12:52.880> putting<00:12:53.199> more<00:12:53.360> and<00:12:53.560> more<00:12:54.000> space<00:12:54.600> between
is putting more and more space between
is putting more and more space between
the<00:12:55.199> galaxies<00:12:56.199> makes<00:12:56.480> it<00:12:56.920> the<00:12:57.079> gravitational
the galaxies makes it the gravitational
the galaxies makes it the gravitational
attraction<00:12:58.160> between<00:12:58.440> them<00:12:58.880> decrease<00:12:59.720> and<00:12:59.800> so
attraction between them decrease and so
attraction between them decrease and so
it<00:13:00.160> impedes<00:13:00.800> the<00:13:00.959> growth<00:13:01.560> of<00:13:01.800> structure<00:13:02.720> so<00:13:02.920> by
it impedes the growth of structure so by
it impedes the growth of structure so by
looking<00:13:03.360> at<00:13:03.600> things<00:13:03.880> like<00:13:04.160> clusters<00:13:04.880> of
looking at things like clusters of
looking at things like clusters of
galaxies<00:13:06.399> and<00:13:07.000> how<00:13:07.680> they<00:13:08.240> um<00:13:08.519> their<00:13:08.720> number
galaxies and how they um their number
galaxies and how they um their number
density<00:13:09.519> how<00:13:09.639> many<00:13:09.880> there<00:13:10.000> are<00:13:10.399> as<00:13:10.480> a<00:13:10.639> function
density how many there are as a function
density how many there are as a function
of<00:13:11.199> time<00:13:11.880> we<00:13:12.000> can<00:13:12.160> learn<00:13:12.600> about<00:13:12.959> how<00:13:13.240> dark
of time we can learn about how dark
of time we can learn about how dark
matter<00:13:13.920> and<00:13:14.079> dark<00:13:14.320> energy<00:13:15.120> compete<00:13:15.560> against
matter and dark energy compete against
matter and dark energy compete against
each<00:13:16.040> other<00:13:16.639> in<00:13:17.120> structure<00:13:17.519> forming<00:13:18.399> in<00:13:18.519> terms
each other in structure forming in terms
each other in structure forming in terms
of<00:13:18.920> dark<00:13:19.199> matter<00:13:20.000> I<00:13:20.079> said<00:13:20.240> that<00:13:20.360> we<00:13:20.440> don't<00:13:20.639> have
of dark matter I said that we don't have
of dark matter I said that we don't have
any<00:13:21.040> you<00:13:21.160> know<00:13:21.560> really<00:13:22.000> persuasive<00:13:22.440> argument
any you know really persuasive argument
any you know really persuasive argument
for<00:13:23.800> uh<00:13:24.000> Dark<00:13:24.279> Energy<00:13:25.040> do<00:13:25.199> we<00:13:25.360> have<00:13:25.560> anything
for uh Dark Energy do we have anything
for uh Dark Energy do we have anything
for<00:13:26.079> dark<00:13:26.360> matter<00:13:26.800> and<00:13:26.920> the<00:13:27.040> answer<00:13:27.279> is<00:13:27.600> yes<00:13:28.399> we
for dark matter and the answer is yes we
for dark matter and the answer is yes we
have<00:13:28.920> have<00:13:29.199> well<00:13:29.440> motivated<00:13:30.040> candidates<00:13:30.480> for
have have well motivated candidates for
have have well motivated candidates for
the<00:13:30.839> dark<00:13:31.120> matter<00:13:31.839> now<00:13:32.079> what<00:13:32.199> do<00:13:32.480> I<00:13:32.600> mean<00:13:32.800> by
the dark matter now what do I mean by
the dark matter now what do I mean by
well<00:13:33.480> motivated<00:13:34.360> I<00:13:34.480> mean<00:13:34.680> that<00:13:34.880> we<00:13:35.120> have<00:13:36.040> um
well motivated I mean that we have um
well motivated I mean that we have um
mathematically<00:13:37.480> consistent<00:13:38.680> theories<00:13:39.680> that
mathematically consistent theories that
mathematically consistent theories that
were<00:13:40.160> actually<00:13:40.680> introduced<00:13:41.680> to<00:13:41.959> explain<00:13:42.519> a
were actually introduced to explain a
were actually introduced to explain a
completely<00:13:43.279> different<00:13:43.639> phenomenon<00:13:44.399> okay
completely different phenomenon okay
completely different phenomenon okay
things<00:13:44.720> that<00:13:44.880> I<00:13:44.959> haven't<00:13:45.160> even<00:13:45.360> talked<00:13:45.680> about
things that I haven't even talked about
things that I haven't even talked about
that<00:13:47.040> each<00:13:47.480> predict<00:13:48.079> the<00:13:48.279> existence<00:13:49.160> of<00:13:49.320> a
that each predict the existence of a
that each predict the existence of a
very<00:13:50.160> weakly<00:13:50.680> interacting<00:13:51.519> new<00:13:51.839> particle<00:13:52.600> so
very weakly interacting new particle so
very weakly interacting new particle so
this<00:13:53.000> is<00:13:53.240> exactly<00:13:53.639> what<00:13:53.759> you<00:13:53.880> want<00:13:54.079> in<00:13:54.279> physics
this is exactly what you want in physics
this is exactly what you want in physics
where<00:13:55.079> a<00:13:55.279> prediction<00:13:55.880> comes<00:13:56.120> out<00:13:56.279> of<00:13:56.399> a
where a prediction comes out of a
where a prediction comes out of a
mathematically<00:13:57.199> consistent<00:13:57.680> theory<00:13:58.199> that
mathematically consistent theory that
mathematically consistent theory that
was<00:13:58.480> actually<00:13:58.880> developed<00:13:59.279> for<00:13:59.480> something
was actually developed for something
was actually developed for something
else<00:14:00.639> but<00:14:00.800> we<00:14:00.920> don't<00:14:01.240> know<00:14:02.040> if<00:14:02.440> either<00:14:03.160> of
else but we don't know if either of
else but we don't know if either of
those<00:14:03.680> are<00:14:04.000> actually<00:14:04.240> the<00:14:04.360> Dark<00:14:04.600> Matter
those are actually the Dark Matter
those are actually the Dark Matter
candidate<00:14:05.800> okay<00:14:06.000> one<00:14:06.240> or<00:14:06.480> both<00:14:07.279> who<00:14:07.440> knows<00:14:07.759> or
candidate okay one or both who knows or
candidate okay one or both who knows or
it<00:14:08.000> could<00:14:08.160> be<00:14:08.279> something<00:14:08.639> completely
it could be something completely
it could be something completely
different<00:14:09.800> now<00:14:10.000> we<00:14:10.120> look<00:14:10.320> for<00:14:10.519> these<00:14:10.720> dark
different now we look for these dark
different now we look for these dark
matter<00:14:11.279> particles<00:14:12.000> because<00:14:12.279> after<00:14:12.480> all<00:14:12.720> they
matter particles because after all they
matter particles because after all they
are<00:14:13.079> here<00:14:13.320> in<00:14:13.440> the<00:14:13.600> room<00:14:14.360> okay<00:14:14.519> and<00:14:14.639> they
are here in the room okay and they
are here in the room okay and they
didn't<00:14:14.959> come<00:14:15.079> in<00:14:15.199> the<00:14:15.320> door<00:14:16.079> they<00:14:16.240> just<00:14:16.519> pass
didn't come in the door they just pass
didn't come in the door they just pass
through<00:14:17.360> anything<00:14:17.720> they<00:14:17.839> can<00:14:17.959> come<00:14:18.120> through
through anything they can come through
through anything they can come through
the<00:14:18.399> building<00:14:18.759> through<00:14:18.920> the<00:14:19.040> Earth<00:14:19.399> they're
the building through the Earth they're
the building through the Earth they're
so<00:14:20.360> non-interacting<00:14:21.360> so<00:14:21.560> one<00:14:21.759> way<00:14:21.880> to<00:14:22.040> look
so non-interacting so one way to look
so non-interacting so one way to look
for<00:14:22.519> them<00:14:22.959> is<00:14:23.079> to<00:14:23.240> build<00:14:23.560> detectors<00:14:24.240> that<00:14:24.360> are
for them is to build detectors that are
for them is to build detectors that are
extremely<00:14:25.360> sensitive<00:14:25.839> to<00:14:26.000> a<00:14:26.120> dark<00:14:26.320> matter
extremely sensitive to a dark matter
extremely sensitive to a dark matter
particle<00:14:27.000> coming<00:14:27.240> through<00:14:27.440> and<00:14:27.600> bumping<00:14:27.959> it
particle coming through and bumping it
particle coming through and bumping it
so<00:14:28.519> a<00:14:28.800> Crystal<00:14:29.199> that<00:14:29.320> will<00:14:29.519> ring<00:14:30.000> if<00:14:30.160> that
so a Crystal that will ring if that
so a Crystal that will ring if that
happens<00:14:30.959> so<00:14:31.160> one<00:14:31.240> of<00:14:31.360> my<00:14:31.519> colleagues<00:14:31.839> up<00:14:32.040> the
happens so one of my colleagues up the
happens so one of my colleagues up the
road<00:14:32.639> and<00:14:32.800> his<00:14:33.000> collaborators<00:14:33.839> have<00:14:33.959> built
road and his collaborators have built
road and his collaborators have built
such<00:14:34.360> a<00:14:34.519> detector<00:14:35.160> and<00:14:35.279> they've<00:14:35.480> put<00:14:35.600> it<00:14:35.839> deep
such a detector and they've put it deep
such a detector and they've put it deep
down<00:14:36.639> in<00:14:36.800> an<00:14:36.959> iron<00:14:37.199> mine<00:14:37.600> in<00:14:37.880> Minnesota<00:14:38.880> okay
down in an iron mine in Minnesota okay
down in an iron mine in Minnesota okay
deep<00:14:39.279> under<00:14:39.440> the<00:14:39.560> ground<00:14:39.839> in<00:14:39.959> fact<00:14:40.120> in<00:14:40.199> the
deep under the ground in fact in the
deep under the ground in fact in the
last<00:14:40.480> couple<00:14:40.680> of<00:14:40.759> days<00:14:41.000> announced<00:14:41.519> the<00:14:41.680> most
last couple of days announced the most
last couple of days announced the most
sensitive<00:14:42.639> results<00:14:43.120> so<00:14:43.360> far<00:14:44.000> um<00:14:44.120> they<00:14:44.199> haven't
sensitive results so far um they haven't
sensitive results so far um they haven't
seen<00:14:44.720> anything<00:14:45.519> okay<00:14:45.880> but<00:14:46.000> it<00:14:46.120> puts<00:14:46.399> limits<00:14:46.800> on
seen anything okay but it puts limits on
seen anything okay but it puts limits on
what<00:14:47.160> the<00:14:47.320> mass<00:14:47.600> and<00:14:47.759> the<00:14:47.839> interaction
what the mass and the interaction
what the mass and the interaction
strength<00:14:48.600> of<00:14:48.720> these<00:14:48.880> dark<00:14:49.040> matter<00:14:49.320> particles
strength of these dark matter particles
strength of these dark matter particles
are<00:14:50.519> there's<00:14:50.720> going<00:14:50.880> to<00:14:51.000> be<00:14:51.320> a<00:14:51.680> satellite
are there's going to be a satellite
are there's going to be a satellite
Telescope<00:14:52.759> launched<00:14:53.120> later<00:14:53.440> this<00:14:53.639> year<00:14:54.480> um
Telescope launched later this year um
Telescope launched later this year um
and<00:14:54.920> it<00:14:55.040> will<00:14:55.279> look<00:14:55.560> towards<00:14:56.000> the<00:14:56.120> middle<00:14:56.399> of
and it will look towards the middle of
and it will look towards the middle of
the<00:14:56.680> Galaxy<00:14:57.160> to<00:14:57.279> see<00:14:57.440> if<00:14:57.560> we<00:14:57.680> can<00:14:57.800> see<00:14:58.079> dark
the Galaxy to see if we can see dark
the Galaxy to see if we can see dark
matter<00:14:58.680> particles<00:14:59.120> annihilating<00:15:00.120> and
matter particles annihilating and
matter particles annihilating and
producing<00:15:01.000> gamma<00:15:01.279> rays<00:15:01.920> that<00:15:02.040> could<00:15:02.199> be
producing gamma rays that could be
producing gamma rays that could be
detected<00:15:02.759> with<00:15:03.000> this<00:15:03.680> the<00:15:03.839> large<00:15:04.279> hron
detected with this the large hron
detected with this the large hron
collider<00:15:05.360> a<00:15:05.480> particle<00:15:05.839> physics<00:15:06.240> accelerator
collider a particle physics accelerator
collider a particle physics accelerator
that<00:15:06.880> will<00:15:07.079> be<00:15:07.480> turning<00:15:07.880> on<00:15:08.240> later<00:15:08.600> this<00:15:08.800> year
that will be turning on later this year
that will be turning on later this year
it<00:15:09.399> is<00:15:09.720> possible<00:15:10.279> that<00:15:10.440> dark<00:15:10.680> matter
it is possible that dark matter
it is possible that dark matter
particles<00:15:11.560> might<00:15:11.759> be<00:15:11.959> produced<00:15:12.360> at<00:15:12.480> the<00:15:12.560> large
particles might be produced at the large
particles might be produced at the large
hydron<00:15:13.199> collider<00:15:14.079> now<00:15:14.279> because<00:15:14.519> they<00:15:14.639> are<00:15:14.839> so
hydron collider now because they are so
hydron collider now because they are so
non-interactive<00:15:16.240> they<00:15:16.320> will<00:15:16.600> actually
non-interactive they will actually
non-interactive they will actually
escape<00:15:17.519> the<00:15:17.680> detector<00:15:18.480> so<00:15:18.680> their<00:15:18.959> signature
escape the detector so their signature
escape the detector so their signature
will<00:15:19.720> be<00:15:20.199> missing<00:15:20.680> energy<00:15:21.680> okay<00:15:21.959> now
will be missing energy okay now
will be missing energy okay now
unfortunately<00:15:22.839> there's<00:15:23.000> a<00:15:23.160> lot<00:15:23.279> of<00:15:23.480> new
unfortunately there's a lot of new
unfortunately there's a lot of new
physics<00:15:24.399> whose<00:15:24.639> signature<00:15:25.199> could<00:15:25.360> be<00:15:25.600> missing
physics whose signature could be missing
physics whose signature could be missing
energy<00:15:26.320> so<00:15:26.480> it'll<00:15:26.680> be<00:15:27.040> hard<00:15:27.240> to<00:15:27.360> tell<00:15:27.560> the
energy so it'll be hard to tell the
energy so it'll be hard to tell the
difference<00:15:28.399> and<00:15:28.800> finally<00:15:29.440> for<00:15:29.759> future
difference and finally for future
difference and finally for future
endeavors<00:15:31.440> there<00:15:31.639> are<00:15:32.120> telescopes<00:15:32.759> being
endeavors there are telescopes being
endeavors there are telescopes being
designed<00:15:33.720> specifically<00:15:34.600> to<00:15:34.800> address<00:15:35.160> the
designed specifically to address the
designed specifically to address the
questions<00:15:35.600> of<00:15:35.759> dark<00:15:36.000> matter<00:15:36.199> and<00:15:36.360> dark<00:15:36.639> energy
questions of dark matter and dark energy
questions of dark matter and dark energy
groundbased<00:15:38.279> telescope<00:15:39.000> and<00:15:39.120> there<00:15:39.199> are
groundbased telescope and there are
groundbased telescope and there are
three<00:15:39.880> space-based<00:15:40.319> telescopes<00:15:40.839> that<00:15:40.920> are<00:15:41.000> in
three space-based telescopes that are in
three space-based telescopes that are in
competition<00:15:41.720> right<00:15:41.880> now<00:15:42.279> to<00:15:42.440> be<00:15:42.560> launched<00:15:43.040> to
competition right now to be launched to
competition right now to be launched to
investigate<00:15:43.959> dark<00:15:44.160> matter<00:15:44.360> and<00:15:44.480> dark<00:15:44.720> energy
investigate dark matter and dark energy
investigate dark matter and dark energy
so<00:15:45.399> in<00:15:45.519> terms<00:15:45.680> of<00:15:45.839> the<00:15:45.959> big<00:15:46.240> questions<00:15:47.240> what<00:15:47.399> is
so in terms of the big questions what is
so in terms of the big questions what is
dark<00:15:47.839> matter<00:15:48.399> what<00:15:48.519> is<00:15:48.680> dark<00:15:49.000> energy<00:15:49.959> big
dark matter what is dark energy big
dark matter what is dark energy big
questions<00:15:50.560> facing<00:15:50.959> physics<00:15:51.759> and<00:15:51.959> I'm<00:15:52.040> sure
questions facing physics and I'm sure
questions facing physics and I'm sure
you<00:15:52.680> have<00:15:52.959> lots<00:15:53.160> of<00:15:53.399> questions<00:15:54.240> which<00:15:54.440> I<00:15:54.680> very
you have lots of questions which I very
you have lots of questions which I very
much<00:15:55.040> look<00:15:55.199> forward<00:15:55.440> to<00:15:55.639> addressing<00:15:56.199> over<00:15:56.399> the
much look forward to addressing over the
much look forward to addressing over the
next<00:15:56.759> 72<00:15:57.240> hours<00:15:57.600> while<00:15:57.720> I'm<00:15:57.920> here<00:15:58.440> okay<00:15:58.720> thank
next 72 hours while I'm here okay thank
next 72 hours while I'm here okay thank
[Applause]
you<00:16:08.000> they<00:16:08.160> have<00:16:08.399> names<00:16:08.920> like<00:16:09.120> idle<00:16:09.519> time<00:16:09.880> books
you they have names like idle time books
you they have names like idle time books
and<00:16:10.720> panther<00:16:11.199> coffee<00:16:11.839> with<00:16:12.040> free<00:16:12.360> enterprise
and panther coffee with free enterprise
and panther coffee with free enterprise
puns<00:16:13.600> like<00:16:13.759> Hue<00:16:14.040> and<00:16:14.240> cry<00:16:14.959> and<00:16:15.160> smash<00:16:15.759> records
puns like Hue and cry and smash records
puns like Hue and cry and smash records
and<00:16:16.920> one<00:16:17.160> Saturday<00:16:17.560> a<00:16:17.759> year<00:16:18.720> small<00:16:19.079> businesses
and one Saturday a year small businesses
and one Saturday a year small businesses
remind<00:16:20.040> a<00:16:20.240> nation<00:16:20.800> of<00:16:20.959> the<00:16:21.160> benefits<00:16:21.639> of
remind a nation of the benefits of
remind a nation of the benefits of
shopping<00:16:22.319> small<00:16:23.319> like<00:16:23.519> the<00:16:23.639> way<00:16:23.839> David<00:16:24.160> Kaplan
shopping small like the way David Kaplan
shopping small like the way David Kaplan
at<00:16:24.680> Shell<00:16:24.959> Lumber<00:16:25.600> shows<00:16:25.880> you<00:16:26.000> how<00:16:26.079> to<00:16:26.199> use<00:16:26.360> a
at Shell Lumber shows you how to use a
at Shell Lumber shows you how to use a
chopsaw<00:16:27.160> then<00:16:28.160> invite<00:16:28.680> you<00:16:28.839> back<00:16:29.079> when<00:16:29.240> the
chopsaw then invite you back when the
chopsaw then invite you back when the
warehouse<00:16:30.120> becomes<00:16:30.480> the<00:16:30.680> community<00:16:31.160> theater
warehouse becomes the community theater
warehouse becomes the community theater
or<00:16:32.319> the<00:16:32.480> way<00:16:32.720> Camille<00:16:33.040> rustler<00:16:33.519> of<00:16:33.720> Ever<00:16:34.000> After
or the way Camille rustler of Ever After
or the way Camille rustler of Ever After
travels<00:16:35.000> the<00:16:35.120> journey<00:16:35.560> from<00:16:35.839> despair<00:16:36.399> to
travels the journey from despair to
travels the journey from despair to
Bliss<00:16:37.279> with<00:16:37.560> every<00:16:37.880> bride<00:16:38.160> to<00:16:38.319> be<00:16:38.800> absolutely
Bliss with every bride to be absolutely
Bliss with every bride to be absolutely
stunning<00:16:40.480> on<00:16:40.680> just<00:16:40.839> one<00:16:41.120> day<00:16:42.120> 100<00:16:42.440> million<00:16:42.800> of
stunning on just one day 100 million of
stunning on just one day 100 million of
us<00:16:43.279> joined<00:16:43.639> a
us joined a
us joined a
movement<00:16:46.079> and<00:16:46.240> Main<00:16:46.560> Street<00:16:47.000> found<00:16:47.279> its<00:16:47.519> might
movement and Main Street found its might
movement and Main Street found its might
again<00:16:48.639> and<00:16:48.800> Main<00:16:49.079> Street<00:16:49.440> found<00:16:49.720> its<00:16:49.959> fight
again and Main Street found its fight
again and Main Street found its fight
again<00:16:51.040> and<00:16:51.240> we<00:16:51.639> the<00:16:51.800> locals<00:16:52.519> found<00:16:52.839> Delight
again and we the locals found Delight
again and we the locals found Delight
again<00:16:54.360> that's<00:16:54.600> the<00:16:54.800> power<00:16:55.079> of<00:16:55.240> all<00:16:55.360> of<00:16:55.480> us
again that's the power of all of us
again that's the power of all of us
that's<00:16:55.920> the<00:16:56.040> power<00:16:56.279> of<00:16:56.360> all<00:16:56.480> of<00:16:56.720> That's<00:16:56.880> The
that's the power of all of That's The
that's the power of all of That's The
Power<00:16:57.279> of<00:16:57.440> all<00:16:57.600> of<00:16:57.759> us
Power of all of us
Power of all of us
that's<00:16:59.480> the<00:16:59.600> membership<00:17:00.240> effect<00:17:00.880> of<00:17:01.120> American
Express
TEDEducation TED-Ed TED Ed, Patricia, Burchat, dark, matter, energy, universe, astronomy
