WEBVTT

00:00:15.547 --> 00:00:17.919
The universe,

00:00:17.943 --> 00:00:20.111
rather beautiful, isn't it?

00:00:20.729 --> 00:00:23.316
It's quite literally got everything,

00:00:23.340 --> 00:00:24.434
from the very big

00:00:24.458 --> 00:00:25.656
to the very small.

00:00:26.394 --> 00:00:29.026
Sure, there are some less
than savory elements in there,

00:00:29.050 --> 00:00:32.109
but on the whole,
scholars agree that its existence

00:00:32.133 --> 00:00:34.208
is probably a good thing.

00:00:34.838 --> 00:00:38.607
Such a good thing that
an entire field of scientific endeavor

00:00:38.631 --> 00:00:40.052
is devoted to its study.

00:00:40.857 --> 00:00:43.253
This is known as cosmology.

00:00:43.277 --> 00:00:46.214
Cosmologists look
at what's out there in space

00:00:46.238 --> 00:00:50.263
and piece together the tale
of how our universe evolved:

00:00:50.287 --> 00:00:51.524
what it's doing now,

00:00:51.548 --> 00:00:53.179
what it's going to be doing,

00:00:53.203 --> 00:00:55.730
and how it all began in the first place.

00:00:55.754 --> 00:01:00.323
It was Edwin Hubble who first noticed
that our universe is expanding,

00:01:00.347 --> 00:01:04.464
by noting that galaxies seem to be flying
further and further apart.

00:01:04.938 --> 00:01:07.224
This implied that everything
should have started

00:01:07.248 --> 00:01:08.868
with the monumental explosion

00:01:08.892 --> 00:01:10.462
of an infinitely hot,

00:01:10.486 --> 00:01:12.071
infinitely small point.

00:01:12.563 --> 00:01:15.369
This idea was jokingly
referred to at the time

00:01:15.393 --> 00:01:17.304
as the "Big Bang,"

00:01:17.328 --> 00:01:18.842
but as the evidence piled up,

00:01:18.866 --> 00:01:22.705
the notion and the name actually stuck.

00:01:22.729 --> 00:01:24.394
We know that after the Big Bang,

00:01:24.418 --> 00:01:25.688
the universe cooled down

00:01:25.712 --> 00:01:28.647
to form the stars and galaxies
that we see today.

00:01:29.166 --> 00:01:32.881
Cosmologists have plenty of ideas
about how this happened.

00:01:32.905 --> 00:01:35.589
But we can also probe
the origins of the universe

00:01:35.613 --> 00:01:40.662
by recreating the hot, dense conditions
that existed at the beginning of time

00:01:40.686 --> 00:01:42.071
in the laboratory.

00:01:42.718 --> 00:01:45.451
This is done by particle physicists.

00:01:46.559 --> 00:01:47.986
Over the past century,

00:01:48.010 --> 00:01:50.161
particle physicists have been studying

00:01:50.185 --> 00:01:53.198
matter and forces
at higher and higher energies.

00:01:53.988 --> 00:01:55.583
Firstly with cosmic rays,

00:01:55.607 --> 00:01:57.838
and then with particle accelerators,

00:01:57.862 --> 00:02:01.966
machines that smash together
subatomic particles at great energies.

00:02:02.408 --> 00:02:04.510
The greater the energy of the accelerator,

00:02:04.534 --> 00:02:07.735
the further back in time
they can effectively peek.

00:02:08.288 --> 00:02:10.851
Today, things are largely
made up of atoms,

00:02:10.875 --> 00:02:13.354
but hundreds of seconds
after the Big Bang,

00:02:13.378 --> 00:02:17.314
it was too hot for electrons to join
atomic nuclei to make atoms.

00:02:17.842 --> 00:02:22.348
Instead, the universe consisted
of a swirling sea of subatomic matter.

00:02:22.935 --> 00:02:24.901
A few seconds after the Big Bang,

00:02:24.925 --> 00:02:26.185
it was hotter still,

00:02:26.209 --> 00:02:28.104
hot enough to overpower the forces

00:02:28.128 --> 00:02:30.804
that usually hold protons
and neutrons together

00:02:30.828 --> 00:02:32.093
in atomic nuclei.

00:02:32.816 --> 00:02:35.608
Further back, microseconds
after the Big Bang,

00:02:35.632 --> 00:02:37.038
and the protons and neutrons

00:02:37.062 --> 00:02:39.794
were only just beginning
to form from quarks,

00:02:39.818 --> 00:02:41.788
one of the fundamental building blocks

00:02:41.812 --> 00:02:44.480
of the standard model of particle physics.

00:02:44.977 --> 00:02:46.002
Further back still,

00:02:46.026 --> 00:02:49.238
and the energy was too great
even for the quarks to stick together.

00:02:50.018 --> 00:02:53.032
Physicists hope that by going
to even greater energies,

00:02:53.056 --> 00:02:57.563
they can see back to a time
when all the forces were one and the same,

00:02:57.587 --> 00:02:59.016
which would make understanding

00:02:59.040 --> 00:03:01.271
the origins of the universe a lot easier.

00:03:01.710 --> 00:03:05.070
To do that, they'll not only need
to build bigger colliders,

00:03:05.094 --> 00:03:07.488
but also work hard
to combine our knowledge

00:03:07.512 --> 00:03:09.169
of the very, very big

00:03:09.193 --> 00:03:11.618
with the very, very small

00:03:11.642 --> 00:03:14.238
and share these fascinating
insights with each other

00:03:14.262 --> 00:03:16.083
and with, well, you.

00:03:16.707 --> 00:03:18.579
And that's how it should be!

00:03:18.603 --> 00:03:22.234
Because, after all,
when it comes to our universe,

00:03:22.258 --> 00:03:24.350
we're all in this one together.