After recently becoming fascinated with astronomy, I thought I would expand on my original article – about the creation of atoms in the heart of dying stars – and make a mini blog series on astronomy. While it is my intention to write about all things space and physics that fascinate me, there is a LOT of ground to cover. It will therefore be a very brief and perhaps superficial look.
The birth of the Universe.
The traditional big bang theory states that our universe began approximately 13.7 billion years ago (though this is disputed) in a singularity followed by a period of rapid expansion. Easy to imagine right? One big explosion. Maybe not.
A singularity is a moment or a point of unimaginable density, heat and an immeasurably small size without dimensions, where quantities become infinite. An analogy by Bill Bryson serves to explain this rather well; Take a proton – that is already exceedingly small (approximately 500,000,000,000 of them could fit into the dot above the ‘i’) – reduce this down to a billionth of its size and then, in this stupendously small space, add about 30 grams of matter.
Of course, this led to an explosion. The very explosion that created our universe at Time = Zero. This is no traditional explosion, more of an extreme expansion. There is no-where to view this explosion from, because outside of the singularity there is nowhere. Nothing. The singularity is not a pregnant, atom filled dot in space. There is nothing around the singularity and there is nowhere for it to be. The dramatic expansion from the singularity is not expanding into empty space because the only space that exists is the space it is creating as it is expanding. Still easy to imagine?
There are many theories as to what this singularity is, where it has come from, has it always been there waiting to ignite, or is it a result of an old universe collapsing on itself in an ever expanding and collapsing cycle (like our lungs). It seems impossible that something so large, awe-inspiring, timeless and as beautiful as our Universe can appear from nothing. And yet it has.
What happened next?
Cosmologists have been able to look back to approximately one trillionth of a trillionth of a trillionth of a second after the big bang. And while the story of the universe’s first breath’s as it opened its eyes is still very murky, Scientists believe that it underwent a period of rapid and dramatic expansion – expanding faster than the speed of light. In less than a minute the universe is a million billion miles across.
One ten-millionth of a second after the big bang gravity is conceived, followed shortly by electromagnetism and nuclear forces. Quickly follows are the elementary particles; protons, neutrons and electrons.
The universe in these early moments is very hot – 10 billion degrees or so – generating enough heat to begin the nuclear reactions that generate the lighter elements (Hydrogen, Helium and Lithium). Within a few minutes 98% of all the matter that is, or will ever be is formed. Of course none of the heavier elements critical for life (Carbon, Oxygen or Nitrogen) are created in this early period, which was one of the big drawbacks of the big bang theory, until Arthur Stanly Eddington suggested in the 1920s that stars gained their energies from hydrogen and helium fusion and thus heavier elements must form inside stars.
The first galaxies were formed approximately a billion years after the big bang. Our solar system is theorised to have formed approximately 4.6 billions years ago – around 8 billion years after the big bang – by a rotating cloud of gas – called the solar nebula – collapsed into a disk by gravity. Most of the matter in this cloud was then drawn into the centre to form our sun. As the sun was forming gravity continues to act, drawing together particles into clumps, over a few million years these chunks began to form objects of about 1000m in diameter. At this point there were about 109 of these objects in the solar system. Gravity continued to play its part and these smaller objects were drawn together to form larger and larger masses. As the sun began to form the temperature of the solar system began to rise, especially in the centre. This resulted in the inner planets being formed from substances with high melting points and large gaseous planets being able to form further out.
The rest as they say is history. Millions of years and many collisions have led to the solar system we know today, the life on our planet, the stars in our galaxy and the awe inspiring deep space objects and galaxies we see beyond our own.
Written by Matt Stephenson