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In the 20th Century, we have gone from

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being ignorants about the surrounding Universe (we only had

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some local knowledge of the Solar System

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and its Planets) to knowing a big percentage of its main properties.

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One of the great observations made last Century,that I believe

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to be fundamental was the discovery of the expansion of the Universe,

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which is something that is not evident at first glance.

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We can see distant objects and Galaxies, almost stable

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in the night sky. Nevertheless, there were some

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observations that suggested that these objects

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weren't actually stable in space but that they were

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all moving away from one another.

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This was proposed by this man here, Sir Edwin Hubble,

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who observed galaxiesthat were nearby our Milky Way

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and demonstrated that they were moving away.

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the way in which these galaxies were moving was not

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fortuitous: the speed of separation was proportional to their distance

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from us, in other words, the furthest galaxies moved

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faster than the ones that were closer to us.

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One of the presumptions that we can infer

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from this movement is the idea that they were

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really close at some previous point in time.

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This implies that the origin of the Universe was probably

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characterized by the condensation of its objects.

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So, this is what underlies the Big Bang theory somehow,

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which I supposed that is something you have already heard of.

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The Big Bang theory suggests that the Universe originated at some point

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in which it was pretty small compared to what it is nowadays.

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Additionally, its initial state was characterized by

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extreme density and temperature.

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>From that moment on, the Universe is expanding,

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time and space were created, and expanded;

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temperatures began to lower meanwhile it expanded;

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and more complex elements were formed little by little.

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Due to the extreme density and temperature in the

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original Universe, there could only exist the elementary particles,

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namely, electrons, quarks, photons (particles associated with light)

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but in the process of expansion and the Universe becoming colder,

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some conglomerations formed, bigger and bigger each time:

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protons and neutrons grouped and formed quarks,

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later on protons and neutrons formed the simplest elements known so far,

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for instance helium, hidrogen (just one proton), litium..

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Later on, atoms were created when electrons

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surrounded those elements... so advancing in the history

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of the Universe, these atoms grouped and the Univers

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eventually became transparent,

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and it was a little bit later when the galaxies

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and other celestial objects were formed.

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Excerpt from the conference held

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November 7th, 2013, at the Residencia de Estudiantes,

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during the sessions "La frontera de la Física Fundamental"

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Full video available at: www.eddaddeplata.org