1
00:00:00,000 --> 00:00:03,400
[ MUSIC ]

2
00:00:03,400 --> 00:00:09,340
Astronomers seem to have revealed a puzzling
detail in the way dark matter behaves.

3
00:00:09,350 --> 00:00:15,000
They found small, dense concentrations of
dark matter that bend and magnify light much

4
00:00:15,000 --> 00:00:17,700
more strongly than expected.

5
00:00:17,700 --> 00:00:24,361
Dark matter is a mysterious, invisible substance
that makes up the bulk of a galaxy. The gravitational

6
00:00:24,361 --> 00:00:29,470
pull exerted by dark matter is thought to
tie galaxies together throughout the universe.

7
00:00:29,470 --> 00:00:35,660
There is so much regular matter and dark matter
concentrated in massive galaxy clusters that

8
00:00:35,660 --> 00:00:40,700
their gravity magnifies and warps light from
distant background objects.

9
00:00:40,700 --> 00:00:46,820
We call this effect “gravitational lensing.”
We can map where the dark matter is in galaxy

10
00:00:46,820 --> 00:00:50,440
clusters by observing how the light bends.

11
00:00:50,440 --> 00:00:54,860
Gravitational lensing distorts the appearance
of background galaxies into deformed shapes

12
00:00:54,860 --> 00:01:01,290
and elongated arcs. Pictures of lensing galaxy
clusters are filled with the smeared images

13
00:01:01,290 --> 00:01:04,009
of remote background galaxies.

14
00:01:04,009 --> 00:01:08,780
The higher the concentration of dark matter
in a galaxy cluster, the more dramatic its

15
00:01:08,780 --> 00:01:14,719
light-bending power is. Smaller clumps of
dark matter associated with individual galaxies

16
00:01:14,719 --> 00:01:21,249
in the galaxy cluster create more distortions.
In some sense, the galaxy cluster acts as

17
00:01:21,249 --> 00:01:26,049
a large lens that has many smaller lenses
embedded inside of it.

18
00:01:26,049 --> 00:01:32,389
But strangely, astronomers found that three
galaxy clusters used in their study had concentrations

19
00:01:32,389 --> 00:01:37,450
of dark matter that are so massive that the
lensing effects they produce are 10 times

20
00:01:37,450 --> 00:01:39,869
stronger than originally expected.

21
00:01:39,869 --> 00:01:46,159
Hubble’s crisp images, coupled with observations
from the very large telescope in Chile, helped

22
00:01:46,159 --> 00:01:50,049
astronomers produce a more accurate dark-matter
map.

23
00:01:50,049 --> 00:01:55,169
By measuring the lensing distortions, astronomers
could trace out the amount and distribution

24
00:01:55,169 --> 00:01:57,609
of dark matter.

25
00:01:57,609 --> 00:02:01,950
This recent study could signal a gap in our
current understanding of the nature of dark

26
00:02:01,950 --> 00:02:06,779
matter and its properties. It shows us that
there’s clearly a missing feature of the

27
00:02:06,779 --> 00:02:12,260
real universe that we simply are not capturing
in our current theoretical models.

28
00:02:12,260 --> 00:02:17,540
With studies like this, astronomers look forward
to continuing to pin down the intriguing nature

29
00:02:17,540 --> 00:02:22,700
of dark matter to better understand the secrets
of our mysterious universe.

30
00:02:22,700 --> 00:02:35,300
[ BEAUTIFUL MUSIC ]