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contenidos

  1. The trip of the photon

  2. Planet formation

  3. How stars are born

  4. A cosmic dance

  5. The ages of the Universe

  6. The sky and its stars

  7. Wenulewfv the word that dream us

  8. The observation of Light

  9. A window to the Universe

  10. An astrophotographer in Santiago Chile

  11. Mysteries of the Cosmos

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editorial

THE MEMORY OF THE RIVERS
While the sweet scent of the canelo
and the laurel medicine trees
rose to the skies
the Parents of my Parents glimmered
as they gazed at the Southern Cross.

Elicura Chihuailaf
Translation: Camila Yver

Cities gather us in different ways, we dwell them, walk around its streets and avenues attending our own eagerness. Many cities have rise over us with huge buildings that show the ability of societies to overcome our scale, and so in a display of phenomenal energy, cities keep moving.

Now days, electric light seems to be a primary need for todays society. Cities and their lights shine over the night sky, blinding our eyes of the ordinary exercise of looking to the starry night that practice our ancestors. Those who have been in the Atacama Desert know that once is late night, looking at the stars there is a different experience, from the one we are used to when we look at the stars from our “shining” cities. This thought becomes most significant while we start to think about our everyday experience. Have we lost something in the way?

Our culture as human beings, have always been related to the night sky observation. Today, new planetary systems are discovered weekly, observation tools and instruments are increasingly sophisticated; we can look at the origin of the Universe and make an image of it. We live in a fast and fascinating era in which we can dazzle with images of supernova’s explosions, nebula clouds and faraway galaxies. The understanding of what “surround us” changes radically and Astronomy raises new questions, challenging the limits of our comprehension. Now we can look farther and farther and so wider the horizon becomes.

Facing this prospect, we propose to add different points of view. Contributing to the astronomical reflection from different angles, being the scientific perspective one in many others possible. Because we are interested in poetry, music, art and design, also in casual conversation, laughter, awkwardness and contradictions, in things that move and those who stay quiet, we are interested in large and small questions of humanity.

This first edition of Galatic Magazine is the number cero and has as main subject the Birth, the origin of things and also the origin of this project. This is a starting point of a conversation that we hope will spread in time, and so will convene many voices and many views.

Javier Quintana

Galactic Magazine
05

The ages of the Universe

TEXT Maja Vučković

ILLUSTRATION Toro

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Who are we and where do we come from? How did the Universe come to be? How big is the Universe? What is the fate of the Universe? If you have ever asked yourself any of these questions – then there is a hidden cosmologist somewhere inside of you! And if you haven’t I am sure that at least once in your life you will ask yourself these kind of questions.

While we can now get some answers like for example how big is our own Galaxy, known as Milky Way*, no one can really know the exact size of the Universe simply cause we can’t see the edge of it, if there is one of course? What we do know, however, is what we can measure and we can measure only what we can observe, so from now on we will be talking here about the observable Universe. Based on the latest estimates the observable Universe, as we see it, is at least 93 000 000 000 light years across.

A light year is the distance light travels in one year – so this would be about 9 000 000 000 000 kms. To put this into a perspective the light from Sun needs a bit more than 8 light minutes to reach us.

But the universe hasn’t always been this size. The most plausible theory tells us that the universe began about 13.8 billion years ago in a Big Bang. At that time, the entire Universe was inside a single point called singularity. It was hotter and denser than anything we can imagine. Then it suddenly exploded. The universe that we know was born. Time, space, matter and energy – it all began with the Big Bang.

A common misconception is that the Big Bang was an explosion that happened out in space. The Big Bang did not happen in a particular place, as space itself only came into existence with the Big Bang. The space was created and then stretched, taking all the matter and energy that makes up the universe with it. In the same way, there was no time before the Big Bang as time also started with the Big Bang: so there was no “before” for anything to be happening in.

In a fraction of a second, the universe grew from smaller than a single atom to bigger than a galaxy. And it kept on growing at a fantastic rate. It is in fact still expanding as we speak! As the universe expanded and cooled, energy converted into particles of matter and antimatter. These two opposite types of particles largely destroyed each other. But some matter survived. More stable particles called protons and neutrons started to form when the Universe was one second old.

Over the next three minutes, the temperature dropped below 1 billion degrees Celsius. It was now cool enough for the protons and neutrons to come together and form hydrogen and helium nuclei. After about 300 000 years, the universe had cooled to about 3000 degrees. Atomic nuclei could finally capture electrons to form atoms. The universe was filled with clouds of hydrogen and helium gas. We cannot see anything that happened during the first 300 000 years of the universe as it was filled with plasma that was opaque to light. The universe at that time was composed of hot plasma of nuclei and electrons. The free electrons made the plasma opaque to the light (radiation) as the photon of energy couldn’t have traveled far before being scattered.

The only direct evidence of the Big Bang itself is a faint glow in space, known as the Cosmic microwave background (CMB) which is, mind the fancy name to it, nothing else but the radiation left over by the Big Bang, the first light to travel across a newly transparent Universe about 380 000 years after the Big Bang. Spacecraft and telescopes on balloons see this CMB as a patchy pattern of slightly warmer and cooler gas all around us.

Cosmic microwave background
Discovered in 1964, by the us radio astronomers Arno Penzias and Robert Wilson, as an inexplicable noise that appeared in their data. The value of these researchers is that they try to comprehend this “noise”, and not delete it. Which end – up giving then Nobel Prize in physics in 1978. The Academy marked out: “Their work is crucial, because make possible to obtain information about a cosmic process that happened during the time the Universe was origin”.

What do you think – how does it look to you? Can you see some structure in it? Some people have been claiming to see Steven Hawking initials written in it… What can you find? To me it looks like the most divine piece of art there is – imagine if the energy with which you came to this beautiful world of ours has been spreading through out the universe ever since and one day scientists find a way to map this birth energy of yours. How would you feel when you would see it? Stunned – that is how I felt when I first saw this image! This what you see is the very first portrait of the birth of our universe! What is even more amazing is that this CMB map shows very strong agreement with cosmological theory – it essentially confirms the Big Bang theory.

Now after we’ve contemplated the fact that we are looking at the oldest light there is lets try to understand what we see! The fact that the map looks patchy (colours mark different temperature) shows that the “soup” of matter filling the early universe varied slightly in density. These ripples also show where the hydrogen clouds were slightly denser. These density variations were the seeds of the stars, galaxies and galaxy clusters that form the large-scale structure we see and live in today.

As millions of years passed, the dense areas pulled in material because they had more gravity. Finally, about 200 million years after the Big Bang, the gas became hot and dense enough for the first stars to form. New stars were being born at a rate that was 10 times higher than in the present-day Universe. Large clusters of stars soon became the first galaxies.

The Hubble Space Telescope and powerful ground-based telescopes are now finding galaxies that were created only about 1 billion years after the Big Bang. These small galaxies were much closer together than the galaxies are today. Collisions were more common. Like two bubbles moving towards each other and uniting into one bigger bubble, the galaxies merged into bigger galaxies. Our Milky Way galaxy was made this way.