The History of the Universe | BIG BANG

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If you put some ice cubes into a glass, you will see the temperature drop to -20oC. You are not that far away from the temperature of the interspace which is -270οC. The kinetic energy of the water molecules is so small that the hydrogen bonds that develop amongst them keep them tied, thus creating the solid form of water: ice.  By adding heat to the system, you will see the temperature rise towards zero.

The molecules start to vibrate more and more intensely. The bonds break and the solid form of ice takes on the liquid form of water. Increase the temperature even more towards 100oC and now the molecules start moving with such high speed that some escape into the air and the water gradually transforms from a liquid into a gas. 

If you increase the temperature further towards 10000 degrees, which is even warmer than the surface of the Sun, you will witness the water molecules colliding so violently that the bonds between the atoms break. Now you have a hot soup of atoms of hydrogen-oxygen and electrons. 

You just broke down a water molecule into its components. 

If you reach 1000000 degrees, which is 1000 times higher than the corona of the sun, the same atoms will have so much kinetic energy that they will even start breaking down into their own components; protons and neutrons. 

At 1,000,000,000,000 degrees, which is warmer than the heart of stars and warmer than a supernova, a temperature that is not physically attainable in any part of the Universe, you would see the same protons and neutrons break down into their elementary components, the quarks.

You just reached the beginning of Creation. Main Video from the author.

I could tell you that the Creation of the Universe happened accompanied by an ear-piercing blast, but the reality is that it happened in total darkness and in deafening silence. In the beginning, there was nothing, and then there was everything. We don’t know much about that first split second (to be exact the first 10 -43 split second).

We can assume that the Universe began as a mathematical point with endless density and temperature, which we call singularity. 

Space, time, matter and light were born from that point. 

10 -35sec after the Big Bang, the niverse is barely the size of a proton when an enormous transformation occurs: cosmic inflation. It almost instantly goes from microcosm to macrocosm, initially the size of an orange, then reaching the size of our solar system and then approaching a million light years in diameter. 

The expansion is so abrupt that it flattens out spacetime and creates the image of the flat, homogeneous and isotropic Universe that we see today. 10-32sec and inflation stops; the Universe continues to expand, but at a slower pace. 

When the temperature drops to 10-27, the four forces of the Universe have separated, starting with gravity, followed by the strong force, then the weak one and finally the electromagnetic force. At this point, bariogenesis begins.


The quarks combine not only to form protons and neutrons, but also their antiparticles. And so begins the battle between matter and antimatter. 

Every time a particle collides with its antiparticle, they annihilate each other, creating a photon in the process. But for every 100,000,000 particles of antimatter, 100,000,001 particles of matter are created. And so, in this battle, matter wins. 

Take a moment to consider that every proton-neutron and electron that make up your body was created in that first fraction of a second after the Big Bang. In the 3 minutes that followed, the protons and neutrons that were left combined to form atoms of hydrogen and helium and traces of lithium. 

The ratio is 75% Hydrogen and 25% helium, which is the ratio that still exists today.

Every atom of lithium that exists in the battery of your cell phone was created 100 seconds after the Big Bang. In the next 380,000 years, the Universe continues to expand, with the temperature constantly dropping yet still remaining high enough for it to be made up of hydrogen and helium ions, while the electrons that remain free scatter the photons, creating a foggy environment. 

Then suddenly the temperature drops to 3000 degrees, the atoms trap the electrons in orbits around them and the photons are now free to escape. 

This is the microwave background radiation that was discovered by accident in 1964 by Arno Penzias and Robert Wilson and it’s the oldest image that we have of the Universe, constituting the modern cosmological model. Very soon, due to the expansion of the Universe, the wavelength of this first light redshifts and the Universe becomes totally transparent and dark. 

In these conditions, another form of matter – dark matter – starts to create gravitational pockets within which the atoms of hydrogen and helium collapse. The gravitational pull becomes so strong that 200,000,000 years after the Big Bang, the hydrogen atoms begin to fuse into nuclear reactions, creating the first stars

Light appears in the universe again. 

The first stars complete their life cycle and the supernova explosions fill the interspace with the elements that will form the basis of life: elements like carbon, oxygen, nitrogen and silicon as well as the heavier elements of the periodic table. 

And thus the first galaxies and clusters of galaxies are created. 

  • 4,6billion years ago, the Sun and planets were formed.
  • 3,5billion years ago, the first forms of life appeared
  • 500,000,000 years ago the first animals and plants appeared.
  • Then 250,000,000 years ago dinosaurs and the first mammals emerged.
  • 6,000,000 years ago the first humanoids appeared and then 300,000 years ago is when the homo sapiens came about.

Today, 13,8 billion years after the Big Bang, the Universe is still expanding and doing so at an accelerated pace according to the most modern cosmological model. According to this model, the constant Λ that was first suggested by Einstein to keep the Universe static and eternal, pushes the expansion of the Universe and constitutes the great mystery called dark energy. This energy, believed to be vacuum energy, amounts to 70% of the Universe’s total energy and will ultimately determine its fate.  

So how big is the Universe? 

360 image from Nasa telescope: Source

Picture a sphere with Earth as its center. The Universe we can observe has a 45-billion-light-year radius, which is essentially the horizon. Whatever is beyond the horizon is invisible to us, because as the Universe expands, the light from the stars beyond the horizon will never have the time it needs to reach us. But even within this volume of space, there are 2 trillion galaxies and each one of them has 100 billion stars.

What is truly incredible is that the matter which forms our own bodies and the matter around us is barely 5% of the total matter and energy that constitutes the Universe. We don’t know anything about the remaining 95%, other than the fact that it is out there. Out of this 95%, 25% is called dark matter and restrains the galaxies and the clusters of galaxies. The remaining 70% has the form of exotic dark energy that pushes the expansion of the Universe. 

This is what makes this science so intriguing. It doesn’t have ready-made answers to nature’s questions, but rather empirical answers that derive through observations and experiments. These answers might be finetuned or might even completely change in the future, just like Newton mechanics gave way to the mechanics of Einstein and quantomechanics.  But this is the way in which we can actually answer the questions we have. 

This is how we progressed out of our caves, this is how we went to the moon, this is the way our cell phones work and this is how medicine and biology keeps us alive. 

We came out of the Savannah just a mere thousand years ago and today we gaze up to the sky and contemplate our place and our destination on this speck of dust.

Stavros Louverdis
Stavros is a graduate of the Department of Physics of the National and Kapodistrian University of Athens. He is from Greece and lives in Athens running his own company.
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