Today, let’s talk about birth…of EVERYTHING.
Sounds quite philosophical, but let’s approach this in a scientific manner. Curious? Good. Let’s get started then.
This is a story that occurred 13.8 billion years ago. There was nothing. No electrons, no light, no matter, no space, no time. Absolutely NOTHING. Total CHAOS.
But, hey! There’s something in the middle of nothing! The ‘thing’ that’s infinitely hot, infinitely dense, infinitely small. The ‘thing’ where almost all the current religions and philosophies seem to converge. The one which we call ‘Brahmanda’, the ‘cosmic-egg’ that spawned everything that exists. The one which we now call the ‘primordial singularity’.
Suddenly, out of the blue, this ‘primordial singularity’ explodes. Make no mistake, this ain’t a normal boom, this is the most violent, most powerful explosion that has ever happened. The explosion that heralded the creation of everything. Known as the ‘BIG BANG’. It’ s rather ironic that all that ever exists is because of that almighty explosion. Also that the ‘most powerful’ explosion had to be the ‘most silent’ explosion, since there was nothing to propagate the sound of the blast…unless you’re standing in the blast wave.
The explosion goes as follows :-
The very beginning of the universe remains pretty murky. Scientists think they can pick the story up at about 10 to the minus 36 seconds — one trillionth of a trillionth of a trillionth of a second — after the Big Bang.
At that point, they believe, the universe underwent an extremely brief and dramatic period of inflation, expanding faster than the speed of light. It doubled in size perhaps 100 times or more, all within the span of a few tiny fractions of a second.
(Inflation may seem to violate the theory of special relativity, but that's not the case, scientists say. Special relativity holds that no information or matter can be carried between two points in space faster than the speed of light. But inflation was an expansion of space itself.)
During the early 20th century, a physicist called Edwin Hubble observed that all the stars are red shifted (for those who don’t know this, red shifting is a phenomenon where an object moves away from an observer and the light it emits gets ‘stretched’ towards the red end of the spectrum). This meant that all the objects are moving away from us at a very fast rate. Rewinding the time, we come to a point where all the matter coincide each other, leading us to the primordial singularity.
At the big bang itself, the universe had zero size and so must have been infinitely hot. But as the universe expanded, the temperature of the radiation would have decreased. One second after the big bang it would have fallen to about ten thousand million degrees. This is about a thousand times the temperature at the center of the sun, but temperatures as high as this are reached in H-bomb explosions. At this time the universe would have contained mostly photons, electrons, and neutrinos and their antiparticles, together with some protons and neutrons. As the universe continued to expand and the temperature to drop, the rate at which electrons and the electron pairs were being produced in collisions would have fallen below the rate at which they were being destroyed by annihilation. most of the electrons and antielectrons would have annihilated each other to produce more photons, leaving behind only a few electrons. About one hundred seconds after the big bang, the temperature would have fallen to one thousand million degrees, the temperature inside the hottest stars. At this temperature, protons and neutrons would no longer have sufficient energy to escape the attraction of the strong nuclear force. They would start to combine together to produce the nuclei of atoms of deuterium, or heavy hydrogen, which contain one proton and one neutron. The deuterium nuclei would then have combined with more protons and neutrons to make helium nuclei, which contained two protons and two neutrons. There would also be small amounts of a couple of heavier elements, lithium and beryllium. One can calculate that in the hot big bang model about a quarter of the protons and neutrons would have been converted into helium nuclei, along with a small amount of heavy hydrogen and other elements. The remaining neutrons would have decayed into protons, which are the nuclei of ordinary hydrogen atoms. These predictions agree very well with what is observed. The hot big bang model also predicts that we should be able to observe the radiation left over from the hot early stages. However, the temperature would have been reduced to a few degrees above absolute zero by the expansion of the universe. This is the explanation of the microwave background of radiation that was discovered by Penzias and Wilson in 1965. We are therefore thoroughly confident that we have the right picture, at least back to about one second after the big bang. Within only a few hours of the big bang, the production of helium and other elements would have stopped. And after that, for the next million years or so, the universe would have just continued expanding, without anything much happening. Eventually, once the temperature had dropped to a few thousand degrees, the electrons and nuclei would no longer have had enough energy to overcome the electromagnetic attraction between them. They would then have started combining to form atoms. The universe as a whole would have continued expanding and cooling. However, in regions that were slightly denser than average, the expansion would have been slowed down by extra gravitational attraction. This would eventually stop expansion in some regions and cause them to start to recollapse. As they were collapsing, the gravitational pull of matter outside these regions might start them rotating slightly. As the collapsing region got smaller, it would spin faster—just as skaters spinning on ice spin faster as the draw in their arms. Eventually, when the region got small enough, it would be spinning fast enough to balance the attraction of gravity. In this way, disklike rotating galaxies were born. As time went on, the gas in the galaxies would break up into smaller clouds that would collapse under their own gravity. As these contracted, the temperature of the gas would increase until it became hot enough to start nuclear reactions. These would convert the hydrogen into more helium, and the heat given off would raise the pressure, and so stop the clouds from contracting any further. They would remain in this state for a long time as stars like our sun, burning hydrogen into helium and radiating the energy as heat and light. More massive stars would need to be hotter to balance their stronger gravitational attraction. This would make the nuclear fusion reactions proceed so much more rapidly that they would use up their hydrogen in as little as a hundred million years. They would then contract slightly and, as they heated up further, would start to convert helium into heavier elements like carbon or oxygen. This, however, would not release much more energy, so a crisis would occur, as I described in my lecture on black holes. What happens next is not completely clear, but it seems likely that the central regions of the star would collapse to a very dense state, such as a neutron star or black hole. The outer regions of the star may get blown off in a tremendous explosion called a supernova, which would outshine all the other stars in the galaxy. Some of the heavier elements produced near the end of the star’s life would be flung back into the gas in the galaxy. They would provide some of the raw material for the next generation of stars. Our own sun contains about 2 percent of these heavier elements because it is a second– or third–generation star. It was formed some five thousand million years ago out of a cloud of rotating gas containing the debris of earlier supernovas. Most of the gas in that cloud went to form the sun or got blown away. However, a small amount of the heavier elements collected together to form the bodies that now orbit the sun as planets like the Earth.
(Source: Stephen Hawking’s Brief history of time)
We, now can still observe the faint clue left behind by big bang explosion, in the form of CMBR (cosmic microwave background radiation), which is the remnant of all the radiations emitted during big bang and the matter-antimatter annihilation during primitive universe, in the form of the static in television.
There is an image of the CMBR caught by WMAP satellite of the ESA (European Space Agency).
Also, since all the atoms in our body are formed out of stellar debri, we can call ourselves ‘THE CHILDREN OF STARS’.
Also, we all truly are the CHILDREN OF STARS.
We must be proud of it.
I apologise for the unavailability of images due to technical problems.
Hope you enjoyed it.
Note:- there are many more theories about the origin of universe apart from the Big Bang theory, like brane theory, superstring theory, also the quantum mechanical version.
Let's see them the next time.
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