0:00:15.547,0:00:17.919
The universe,

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rather beautiful, isn't it?

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It's quite literally got everything,

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from the very big

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to the very small.

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Sure, there are some less[br]than savory elements in there,

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but on the whole,[br]scholars agree that its existence

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is probably a good thing.

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Such a good thing that[br]an entire field of scientific endeavor

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is devoted to its study.

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This is known as cosmology.

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Cosmologists look[br]at what's out there in space

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and piece together the tale[br]of how our universe evolved:

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what it's doing now,

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what it's going to be doing,

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and how it all began in the first place.

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It was Edwin Hubble who first noticed[br]that our universe is expanding,

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by noting that galaxies seem to be flying[br]further and further apart.

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This implied that everything[br]should have started

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with the monumental explosion

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of an infinitely hot,

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infinitely small point.

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This idea was jokingly[br]referred to at the time

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as the "Big Bang,"

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but as the evidence piled up,

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the notion and the name actually stuck.

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We know that after the Big Bang,

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the universe cooled down

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to form the stars and galaxies[br]that we see today.

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Cosmologists have plenty of ideas[br]about how this happened.

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But we can also probe[br]the origins of the universe

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by recreating the hot, dense conditions[br]that existed at the beginning of time

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in the laboratory.

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This is done by particle physicists.

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Over the past century,

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particle physicists have been studying

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matter and forces[br]at higher and higher energies.

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Firstly with cosmic rays,

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and then with particle accelerators,

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machines that smash together[br]subatomic particles at great energies.

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The greater the energy of the accelerator,

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the further back in time[br]they can effectively peek.

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Today, things are largely[br]made up of atoms,

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but hundreds of seconds[br]after the Big Bang,

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it was too hot for electrons to join[br]atomic nuclei to make atoms.

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Instead, the universe consisted[br]of a swirling sea of subatomic matter.

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A few seconds after the Big Bang,

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it was hotter still,

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hot enough to overpower the forces

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that usually hold protons[br]and neutrons together

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in atomic nuclei.

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Further back, microseconds[br]after the Big Bang,

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and the protons and neutrons

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were only just beginning[br]to form from quarks,

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one of the fundamental building blocks

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of the standard model of particle physics.

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Further back still,

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and the energy was too great[br]even for the quarks to stick together.

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Physicists hope that by going[br]to even greater energies,

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they can see back to a time[br]when all the forces were one and the same,

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which would make understanding

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the origins of the universe a lot easier.

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To do that, they'll not only need[br]to build bigger colliders,

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but also work hard[br]to combine our knowledge

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of the very, very big

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with the very, very small

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and share these fascinating[br]insights with each other

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and with, well, you.

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And that's how it should be!

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Because, after all,[br]when it comes to our universe,

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we're all in this one together.