To start, let’s see how insignificant an individual is. Start with your house address. House 1, xyx street, sector xyz, city xyz, state xyz, country xyz, continent xyz. This gives you a broad prospect, however, you are even more insignificant because you live on planet earth, in the solar system, in the milky way, in the local cluster, then the Virgo supercluster, and then finally in the universe. The universe is much bigger, denser, hotter, and more fascinating than you can imagine.

This is known as the cosmic address. Essentially the cosmic address serves the objective of showing that you are not unique. This was devised by a man most people know as Nicolaus Copernicus. He stated that the earthlings on earth, are not ‘privileged observers’ of the universe. This however went against the church’s belief in a geocentric system. w Instead of surrendering to the prospect of multiple worlds and another god, the church found it easier to mark Copernicus as a heretic and go on with its merry life. Many people such as Galileo Galilei agreed with Copernicus and felt that the solar system was heliocentric. 

The theory of heliocentricism turned out to be true, and that more or less proved the Copernican principle true. However, when sophisticated equipment was used to survey the sky, it was observed that celestial bodies seemed to be shifting away from us.  When a star emits light, there is a certain wavelength of light that reaches us. A shorter wavelength depicts shorter distances, whereas long wavelengths show a longer distance. Short wavelengths are blue, and longer ones are red. As the astronomers observed, it appeared that all the stars, in every direction appeared to ‘redshift’, or move away from us. Now, this seemed to violate the Copernican principle because it showed that the earth is special (not in a good way though), and all other celestial bodies were moving away from us!

What this seemed to suggest was that earth was somewhere in the centre of the universe, and probably smelled bad, because every single celestial object was moving away from us! But thanks to the Copernican principle we know that this cannot be. A lot of theories were created, and a fascinating one of those is the ‘Exploding Egg model’. This states that there was an egg (not really but this just helps us understand it better), and it exploded, squirting galaxies all across the empty universe.

The issue that this model poses, is that the explosion would be very uniform, and it would be like a sphere, whose outer edges are made of galaxies but is hollow inside. There would also be an edge to the universe beyond which we can’t see anything. This is not the way we see things, because we need to be a part of the edge, so we would see a very strange pattern of galaxies. However as recently seen, the ‘Hubble Ultra Deep Field’ is an image in which you can zoom in to amazing distances and still see galaxies!

So the exploding egg model has been disproved, as we can see galaxies in the ‘hollow’ area which is an inevitable part of the exploding egg model.

Now, in the 1900s, a remarkable discovery was made by a man called Edwin Hubble. He observed these galaxies and tried to find the rate of redshift. He noted that galaxies away from us moved faster than ones closer to us! This again brought up the Copernican Concern! Hubble analyzed this issue and soon came up with a solution. He showed that the universe expands, and the reason that the speed disparity exists, is because the celestial bodies aren’t moving, it’s the space between them that is stretching. Now when there is a greater distance between two galaxies, there is more space to stretch, and hence a greater amount and speed. When there is less distance, there is less scope for speed. This law is called the Hubble Law.

So far we have an idea of the exploding egg model and Hubble Law. we have replaced the egg model with the Hubble Law, but this law only explains why we see a disparity in speeds, and not how the universe began in the first place.

The popular belief is that the universe began with what scientists call ‘The Big Bang’. This theory has subdivisions as well, which will be explained soon. The theory goes something like this. There was initially nothing, aside from two lonely particles known as the ‘Higgs Boson Particles’. When they collided, they expanded, creating new and new matter as they moved along. Certain parts of the generated matter spun hard, and some were unstable. The speed of expansion was extremely fast at this point, and hot. Some even say that the speed was faster than light.

As the universe started cooling down, it entered a phase called the ‘Dark Ages’. At this point, the universe was much smaller than it is today, it was very empty, and the earliest stars were born. The large chunks of matter would attract other forms of lighter matter and in such ways, these stars would form. 

Next was the stage of reionization. In this stage, large clumps of matter would merge, forming quasars and black holes. (These forms will be explained later). Early galaxies were also formed in this stage. The masses of stars wrapped around black holes, and got clustered together.

After reionization, the longest period lasted. This period is the matter-dominated era. Millions of galaxies were born, Our milky way and it’s neighbour Andromeda were born. Near the end of this era, our universe began to accelerate faster again, and next was our solar system. The earth was one of the early planets in the solar system, and soon after, water was found as the earth evolved. After that, single-celled life such as amoebas were born, and they mutated into plants, and others mutated into multicellular life. Then vertebrates were born, and they finally evolved into humans. If you see, humans are very very new to the universe.

Now, let us talk about CMB. In 1964, two radio astronomers known as Arno Penzias and Robert Wilson were giving a lecture on their radio findings in the universe. Their findings had a consistent buzzing and crackling feedback, and they felt it was random. However, the spectators had a different verdict. The way they put it was, “Either you two fools have discovered bird shit or the beginning of the universe.” The pair then scraped the bird poop off their antennae, only to see that the feedback persisted.

You see, in the early stages of the universe, all the matter colliding with other matter sent many microwave rays throughout the universe. As the universe is ever-expanding, these rays never stop and continue outwards. This radiation is now known as Cosmic Microwave Background, (CMB).  Analyzing the data and frequencies allows us to see that the universe really did start from a single point. CMB acts as solid evidence for the Big Bang. interestingly, much of the radio static you hear in your cars today is actually remnant CMB from the big bang. Arno and Robert won the 1978 Nobel Prize in physics for their discovery.

The reason we see this CMB is because the early universe was full of hydrogen and photons. The photons would bounce off the hydrogen atoms and would continue to move about. The required energy to eliminate an electron from a hydrogen atom is exactly 13.6 Electron Volts, and all the bouncing caused the speed to result in that energy. As they knocked electrons out of orbit, instead of being trapped among hydrogen, the photons shot through thy hydrogen and reached us today.

Now let’s see the variational subtopics of the big bang, starting with inflation. Inflation is a theory that states that the speed of the universe’s expansion, was accelerating. This was modelled on the observation that redshift levels were exponentially increasing. This results in two possible endings, either the universe ends in a big crunch or a big rip. Considering that the universe expands at the speed of light, perhaps another universe bumps into our, reversing the angle of expansion. Instead of outwards, the universe speeds inwards. The edges of the universe collide, and CRUNCH! It gets compressed into another microscopic point, which would then expand again.

Suppose that no other universe collides with ours, and it continues to accelerate. The fabric of spacetime, like any other fabric would eventually be under so much stress, that it would rip. Now considering that we don’t know what the universe is expanding into, or whether there are other universes, it’s tough to determine what would happen to the ripped universe. Perhaps its contents will leak out the rip due to some insane gravitational pull outside the galaxy. Perhaps there is a spherical gravitational pull due to which the universe would expand in the first place. Maybe this force would not only rip the universe but shred its contents as well. Nobody knows for sure. One theory could be that this fabric, upon ripping also rips the galaxies along the line of the cut. Maybe not many effects would take place, barring a few galaxies cut in half.

The Big crunch, also has an elaborate theory. Let’s assume that the universe, due to some unforeseen reason begins to shrink. Let’s also assume that the universe in a broad sense has the properties of light. Light as we know has no mass. So when the universe collapses onto one point, we create a singularity. This singularity clots all the mass, including galaxies, stars, planets, etc. the only thing that has no mass, like the universe, will refract past the singularity, much like how the light does in a telescope. This gives another life to the universe, which then starts off as another fresh universe. Perhaps our own universe is the refracted version of another.