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The universe,
rather beautiful, isn't it?
It's quite literally got everything,
from the very big
to the very small.
Sure, there are some less than savory elements in there,
but on the whole, scholars agree that its existence
is probably a good thing.
Such a good thing, that an entire field
of scientific endeavor is devoted to its study.
This is known as cosmology.
Cosmologists look at what's out there in space
and piece together the tale of how our universe evolved:
what it's doing now,
what it's going to be doing,
and how it all began in the first place.
It was Edwin Hubble who first noticed
that our universe is expanding
by noting that galaxies seem to be flying
further and further apart.
This implied that everything should have started
with the monumental explosion
of an infinitely hot,
infinitely small point.
This idea was jokingly referred to at the time
as the "Big Bang,"
but as the evidence piled up,
the notion
and the name
actually stuck.
We know that after the Big Bang,
the universe cooled down
to form the stars and galaxies that we see today.
Cosmologist have plenty of ideas
about how this happened.
But we can also probe the origins of the universe
by recreating the hot, dense conditions that existed
at the beginning of time in the laboratory.
This is done by particle physicists.
Over the past century,
particle physicists have been studying
matter and forces at higher and higher energies.
Firstly with cosmic rays,
and then with particle accelerators,
machines that smash together
subatomic particles at great energies.
The greater the energy of accelerator,
the further back in time they can effectively peek.
Today, things are largely made up of atoms,
but a hundreds of seconds after the Big Bang,
it was too hot for electrons to join
atomic nuclei to make atoms.
Instead, the universe consisted of
a swirling sea of subatomic matter.
A few seconds after the Big Bang,
it was hotter still,
hot enough to overpower the forces
that usually hold protons and neutrons together
in atomic nuclei.
Further back, microseconds after the Big Bang,
and the protons and neutrons were only just beginning
to form from quarks,
one of the fundamental building blocks
of the standard model of particle physics.
Further back still,
and the energy was too great even
for the quarks to stick together.
Physicists hope that by going to even greater energies,
they can see back to a time
when all the forces were one in the same,
which would make understanding
the origins of the universe a lot easier.
To do that, they'll not only need to build bigger colliders,
but also work hard to combine our knowledge
of the very, very big
with the very, very small
and share these fascinating insights
with each other and with,
well, you.
And that's how it should be!
Because, after all,
when it comes to our universe,
we're all in this one together.


【TED-Ed】宇宙是如何形成的? The beginning of the universe, for beginners - Tom Whyntie

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VoiceTube 發佈於 2013 年 4 月 23 日
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