Imagine all the space around you, all that you can see, to the horizon and beyond, much-much beyond, space that is spread out millions and millions of light years across, all crunched in a tiny dot, so tiny that you probably can’t even see it!!
Seems improbable? It not only seems improbable, it seems impossible. But, this is exactly how it was. It is the origin of our existence!
What’s a light year?
It is the distance that light travels in one year. To help you get an idea of the scale that I am talking about -- light travel the distance between Sun and Earth – 150,000,000 km (mean distance) -- in eight minutes. Now imagine one light year!
Tighten your seatbelts, I’m going to take you thru’ a journey of your lifetime, literally.
It just happened. That it happened we know, with reasonable degree of accuracy, why did it happen no one knows. Big Bang is what it is called. A tiny dot exploded and expanded. It was not an explosion as we are familiar with; it was an explosion that created space and time as it happened. It created what we call universe.
In the beginning, the universe had zero size and infinite temperature. A second after the Big Bang the temperature had dropped to ten thousand million degrees. At this time, the universe was a dense soup of elementary particles – photons, electrons, neutrinos and their anti particles, together with some protons and neutrons.
What’s an anti particle?
Anti particle is a twin of elementary particle, each elementary particle has one. The difference between the anti particle and the elementary particle is that, it has same mass as the elementary particle but opposite charge.
You know there is something called anti matter as well?
When anti matter comes in contact with regular matter, a sort of nuclear fission takes place that produces energy equivalent to the antimatter and the regular matter.
As the space time continued to expand and the temperature continued to drop, the rate of creation of electron and anti-electron fell below the rate at which they were being annihilated, producing photons in the process. Only neutrinos and anti neutrinos remained as they were inert particles. (Neutrinos have same mass as electrons, but unlike electrons they are without any electric charge).
Hundred seconds from Big Bang, the temperature cooled to one thousand million degree. At this temperature neutrons and protons could no longer stay independent. The strong nuclear forces took over and combined neutrons and protons into heavy hydrogen (Hydrogen with 1 proton and 1 neutron. Normal hydrogen has only 1 proton). The heavy hydrogen further captured 1 more proton and 1 more neutron to create helium. It is calculated that 25% of all neutron and proton became helium. Rest of the neutrons decayed and became protons, which is the nucleus of ordinary hydrogen.
This continued for a few hours and then no more helium was created. The universe remained like this for millions of years.
As the universe cooled to a few thousand degrees, the electromagnetic forces became strong enough to bring the nuclei and electrons together to form atoms. As the universe expanded and cooled, some regions where the density of the matter was more than at other places, the expansion slowed down because of extra gravitational force. This made some parts of the universe to start collapsing.
As the matter collapsed on to itself, the gravitational pull from matter outside started them rotating. Eventually, the centrifugal force generated by rotation balanced the gravitational pull from the matter outside. This led to the creation of galaxies. Within these galaxies, the gas clouds kept on collapsing and getting hotter, till it reached a state where nuclear fusion started. In these nuclear fusion reactions, hydrogen was converted into helium. These were first generation stars.
Picture 1 – Star creation
The bigger the star, more quickly it burned its hydrogen into helium and shorter its lifespan. Star like our Sun has a life span of 9 billion years, some massive stars die within a million years and some stars have a life of 100 billion years.
The energy that is produced as a result of nuclear fusion, in star’s core, is what counteracts star’s own gravity and holds it up. After hydrogen is all burned into helium in the core, the helium left in the core starts collapsing again. As it collapses, the pressure and the temperature increase. For massive stars the pressure and temperature increase to such a degree that helium starts fusing together to make even heavier elements like carbon and oxygen. Our Sun will never reach a state where it starts burning helium. It will just extinguish after burning hydrogen. In the stars that have mass up to 8 times our Sun, helium fuses into carbon and that is the end for them.
For stars that are even bigger, the fusion does not stop after fusing helium, they keep fusing heavier atoms. Fusing atoms that produce atoms that are heavier than iron is not efficient, the reaction consumes more energy than it releases. That is where the fusion stops for the massive stars.
For massive stars, the end is very violent. As they reach the end of their fusion cycle, they run out of energy to counteract gravity, the outer core speeds towards the inner core at the speed of 70,000 km/sec. This heats up the core causing decay of iron nuclei into helium and decay of proton into neutron and neutrinos. Neutrinos escape the core carrying with them the energy and further accelerating the collapse. The star’s core detaches from the star’s outer layers as the speed at which the core collapses on itself is more than the speed at which the outer layers collapse. The collapse is eventually halted by the short range neutron-neutron repulsive forces. At this stage the density of the star is as much as that of nucleus of an atom. When the collapse stops, the in-falling material (outer core and outer layers) rebounds of off the core, this creates tremendous shock waves resulting in the explosion of the star. This explosion, called super nova, is responsible for scattering the life supporting heavy elements far and wide.
Our sun is a second or third generation star that is made up of remnants of an exploded star. The solar system bodies, including our Earth, are a product of the elements that were part of some massive star in the past. And so is everything that is on the Earth.
Some part of you, at some point in time in the past, was cooked in the core of a massive star. We are all star dust!
The question that still remains is the advent of consciousness. How did it come about? Is it the result of some weird chemical reaction that took place under some weird circumstances creating organic material from inorganic? Or are we now getting in the religion’s territory?
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