The Story of Our Universe

          “In the beginning God created the heavens and the earth.  Now the earth was a formless and empty, darkness was over the surface of the deep, and the Spirit of God was hovering over the waters.” –Genesis 1:1-2

            Where are we?  Where did we come from?  How did our universe come into being?  These are the questions that have been asked since the dawn of our existence yet we still have not fully answered them.  A common characteristic of most religions is a creation myth to explain the Beginning.  Humans have often attributed these inquiries to the supernatural and claimed they are eternally beyond the realm of human knowledge.  Despite these claims, creative people have attempted to answer them and have come up with countless theories. In this article, we will explore the evolution of the cosmos.

            In the beginning, there was something.  No one is certain of what that something was but our current understanding of it is that the universe was incredibly small (much smaller than the radius of an atom’s nucleus).  In extremely small scales, quantum physics gives us the best description of the system.  We also know that energy must be conserved, so all of the energy that currently exists existed before in some form (mass, light, thermal motion).  Thus, Einstein’s theory of general relativity must be used to model such massive systems.  Presently, quantum mechanics and general relativity are incompatible so we need a more powerful, more general theory to explain what happened at the beginning.  One of the hopes in theoretical physics is that string theory may provide an answer to what this initial state was.

            Whatever there was in the beginning, a tremendous explosion took place.  It sent particles in all directions, creating a sphere of dispersing energy.  The universe was so hot that all the matter was in the form of elementary particles (they cannot be broken down into smaller pieces; an example would be an electron).  Most of this inflation took place between 10^-36 seconds and 10^-32 seconds after the Big Bang where the universe’s volume increased by a factor of 10^78.

            What is interesting to note is how the dimensions of space came to be the way they are now.  According to some models, our universe has more than three spatial dimensions (e.g. there are 10 spatial dimensions in M-theory).  The reason we do not notice the extra dimensions is because they are tightly curled up within the three macroscopic dimensions.  (From a biological standpoint, our ancestors did not need to develop the ability to perceive more than three dimensions to survive.)  Why did three of the dimensions expand while the other seven remained small?  A theoretical physicist at Harvard, Cumrun Vafa, proposed one solution.  What may have happened was that some of the strings were wrapped around the extra dimensions and constricted them from expanding.  Three of the dimensions were freed because in three dimensions, randomly moving strings are likely to collide into each other.  This caused them to annihilate and the freed dimensions were able to expand.

As the universe expanded, it began to cool down.  At this point, more massive, composite particles like the proton formed and eventually bonded with free electrons to form hydrogen, the simplest atom (one electron orbiting around a single proton).  (A proton is three quarks bound together by the strong nuclear force.  The strong force is the strongest of the four forces; it is 100 times stronger than the electromagnetic force, 10^13 times the weak force, and 10^38 times the gravitational force.)  The stage was set for star systems to form.

Stars are massive spheres of plasma, mostly in the form of hydrogen.  Plasma is like a gas in which some of the atoms have been ionized.  Stars act as giant furnaces where hydrogen undergoes nuclear fusion to produce helium and virtually all naturally occurring elements heavier than helium.  Although gravity keeps most of the star’s mass compacted into the sphere, the weak force that is responsible for the radioactive decay emits particles out of the star as well.  This is why our Sun gives off light at various frequencies and many dangerously energetic electrons and protons.  Fortunately, our planet has a magnetic field that shields us from these “solar winds.”

After many billions of years, a massive star can suddenly collapse and explode.  This is called a supernova.  It is so luminous that it can temporarily outshine the star’s neighboring galaxy.  They play a vital role in creating elements heavier than oxygen and distributing them throughout the universe.  At the same time, they are incredibly dangerous.  Even if a supernova exploded 3000 light-years away from the Earth, every species would evaporate away from the heat.

This covers the first several billion years of the universe’s existence.  There is still much more to discuss: black holes, the geometry of space-time, the universal expansion rate, the formation of planets, the inception of life and its evolution, and the death of the universe (and how we could survive it).  We are made up of the same elementary particles of which planets, moons, asteroids, stars, and galaxies are made.  Through us, the universe is now conscious of its existence begins its quest to discover what it is.  I hope this brief overview encourages you to look deeper into the fascinating nature of everything around us.