How All This Started According to Big Bang Theory
Excerpts from my upcoming book
Hello THG readers. The time has now come to test how lucid is my writing in the new book for lay readers. Whole of the book is science-heavy but I have chosen this particularly pure-science part which, in turn, heavily quotes from the works of popular American astrophysicist Neil deGrasse Tyson. The book is, for now, titled Before Midnight: Biography of a Troubled Plant - From Creation to Climate Crisis but the title may change by the time the book is out.
As this is a privilege granted only to THG readers, I will be disappointed if you read but leave without commenting about either the substance or the presentation of the text! I would be doubly grateful if you let your children (my hope is, students in grade 9 or more will grasp this) Now please enjoy this now:
(Section describing the early part of the Universe’s Creation Story)
According to the Big Bang theory of the origin of universe, it all started with a minuscule point termed singularity some 13.7 billion years ago.
Where did that singularity come from? We don't know now and we are unlikely to know about it any time soon. That is because it is clearly beyond the scope of science today.
As the astrophysicist Neil deGrasse Tyson explains lucidly in his book 'Astrophysics for People in a Hurry', prior to the Big Bang, that singularity, sized one trillionth of a period, contained all the space, matter and energy that would subsequently form the universe.
Needless to say, its density and temperature were both infinitive.
Between Big Bang itself (t=0) and one ten-million-trillion-trillion-trillionth of a second (t=10-43s) named the Planck era, we don't know exactly what happened. By that time the universe had expanded to one billion-trillion-trillionth of a meter.
But soon after the end of that era, as Tyson explains, Gravity (which binds bulky matter together) wriggled loose from the other still unified forces of nature achieving an independent identity.
As the universe aged through 10-35 seconds, it continued to expand, diluting all the concentrations of energy and what remained of the unified forces split into strong nuclear forces (that binds the atomic nucleus) and electroweak forces.
Later still, the electroweak force split into electromagnetic (which binds molecules) and weak nuclear forces (which controls radioactive decay) thus resulting in four distinct forces that we have come to know.
All this happened, yet just a trillionth of a second had passed.
From that point until one millionth of a second, the universe had expanded to a size larger than our solar system and the temperature had dropped to below a trillion degrees Kelvin.
Now you can imagine the rate at which the early universe must have expanded!
How can we be so sure about the expansion of universe beginning 13.7 billion years ago? What if the universe was today's size from the beginning itself? These are valid questions.
Until 1929 even scientists assumed that the universe was steady. Then came along an astronomer named Edwin Hubble and discovered that the galaxies being observed with telescopes were receding from earth and one another.
Bingo! The Universe is expanding.
An expanding universe meant that if you followed it backwards, it would shrink as you move on. The logical endpoint of that process would be an infinitely dense point.
If universe originated from such single source, it was plausible that there would be some signature finding to be found everywhere.
After decades of search, astrophysicist Arno Penzias and radio-astronomer Robert Wilson, incidentally discovered such signature in 1965.
That signature is termed Cosmic Microwave Background (CMB) and is supposed to be the truly omnipresent radiation originating at the Big Bang and reaching everywhere the expanding universe reaches.
Now, though, let's follow the story of the evolution of the universe according to Big Bang theory.
During the period between one trillionth of a second and a millionth of a second, the universe was a sheething soup of quarks (that make up protons and neutrons), leptons (electron is a lepton) and their antimatter siblings, along with bosons (a photon, the unit of light, is a boson).
The universe was then hot enough for the photons to spontaneously convert their energy into matter-antimatter particle pairs, which could immediately thereafter annihilate one another, returning their energy back to photons.
Einstein's famous equation (E=mc2) precisely explains this back-and-forth transition between particle and energy.
If every particle was annihilated by its antiparticle pair, how did the universe end up with so many particles including those which make up your body and mine? Let me quote Tyson directly here:
Strong theoretical evidence suggests that an episode in the very early universe, perhaps during one of the force splits, endowed the universe with a remarkable asymmetry, in which particles of matter barely outnumbered particles of antimatter: by a billion-and-one to a billion.
This asymmetry is at the heart of the particle-rich universe we see today. Without it, the universe now would have been awash in light but without any particle!
All this may sound like a fairy tale full of theoretical abstractions but it is not.
At the Large Hadron Collider (LCH) in Switzerland the scientists have attempted to create the conditions similar to the early universe. Among many startling discoveries made by LCH, they have been able to capture the first instances of the matter-antimatter asymmetry.[1]
At around a millionth of a second of age, the universe transitioned from the quark era of light particles to hadron era of heavy particles.
That meant the universe was cold and stable enough for the quarks to combine into heavy particles like protons and neutrons termed hadrons. With leptons like electrons already there, and with the background knowledge about the structure of atoms taught in the school, you must have already guessed which way this evolution of the universe is heading.
The annihilation of particles and antiparticles, nonetheless, persisted during this era. And the asymmetry from the quark era persisted too. The result: for every billion annilhilations between protons and antiprotons, one proton would survive and get to wander through the universe. Same thing held true for a neutron.
It is entirely possible that some of the protons from your body (with lifespans in the order of 1034 years) can be dated all the way back to the moment a millionth of a second after the Big Bang! (Not so for the neutrons, though, which are far more unstable with the half-life of a free neutron in the order of minutes.)
By one second, the universe had grown to a few light years across and a billion degrees hot. The annihilation of electrons and positrons continued to this era and so did the asymmetry resulting in surviving electrons (with lifesapns in the order of billions of years) some of which may still be responsible for carrying the electrical activity from your eyes to the brain as you read this text.
With continuous expansion and cooling of the universe, though, the relentless annihilations get less frequent as seconds pass. Right about now, as Tyson explains, one electron for every proton has been frozen into existence:
As the cosmos continues to cool—dropping below a hundred million degrees—protons fuse with protons as well as with neutrons, forming atomic nuclei and hatching a universe in which ninety percent of these nuclei are hydrogen and ten percent are helium, along with trace amounts of deuterium("heavy" hydrogen), tritium (even heavier hydrogen), and lithium.
By two minutes of existence, we have now ended up with a few basic elements. After a lull of 380,000 years, as the temperature of the universe fell below 3,000 degrees Kelvin (about half the temperature at the sun's surface), all the free electrons combined with nuclei completing the formation of particles and atoms in the primordial universe.
While this all was happening at the atomic level with strong nuclear force setting the stage for formation of elements, the universe itself kept expanding and cooling as matter gravitated into the massive concentrations of particles called galaxies.
At the time Tyson wrote the book which was published in 2017, he mentions that ''Nearly a hundred billion of them [galaxies] formed each containing hundreds of billions of stars…''. Now in 2023, though, it is widely accepted that there are around 2 trillion galaxies in the universe.
As NASA's James Webb Space Telescope and the European Space Agency's Euclid Space Telescope examine the previously unseen parts of the universe, that number may surely move upwards in the coming days.
All the stars in those galaxies have been undergoing thermonuclear fusion at their cores. The process in which the two atoms of a lighter element (say hydrogen) fuse with each other forming an atom of a heavier element (helium) and converting a minuscule part of the mass into energy—as represented by the equation E=MC2—is termed nuclear fusion.
Tyson once again:
Those stars more than about ten times the mass of the sun achieve sufficient pressure and temperature in their cores to manufacture dozens of elements heavier than hydrogen, including those that compose planets and whatever life may thrive upon them.
… High-mass stars fortuituously explode, scattering their chemically enriched guts throughout the galaxy [thereby enabling the formation of a new generation of stars and planets]. After nine billion years of such enrichment, in an undistinguished part of the universe (the outskirts of the Virgo Supercluster) in an undistinguished galaxy (the Milky Way) in an undistinguished region (the Orion Arm), an undistinguished star (the Sun) was born.
The energy required for the birth of the Sun by condensation of the dust and gas in the space was provided by a supernova in the nearby region of the space. A supernova is a powerful and luminous explosion of a star that occurs during the last evolutionary phase of a massive star. It releases a tremendous amount of gas and energy in the region of the space around it.
This is how NASA's page titled Our Solar System describes the birth of sun[i]:
When this dust cloud collapsed, it formed a solar nebula – a spinning, swirling disk of material.
At the center, gravity pulled more and more material in. Eventually, the pressure in the core was so great that hydrogen atoms began to combine and form helium, releasing a tremendous amount of energy. With that, our Sun was born, and it eventually amassed more than 99% of the available matter [in the solar system].
The newer stars thus tend to have heavier elements manufactured by their exploding predecessors. Given the composition and complexities of the elements in the solar system our sun is said to be at least a third generation star.
To this date, the sun has been burning using its hydrogen reserve and converting it to helium. The day it uses up that reserve, the region of the space where we dwell will go dark making life of any kind impossible.
Out of the billions of masses formed using up the energy released by that supernova, many which were close to the sun were swallowed up by it. According to Newtonian physics, the masses that were farther enough to avoid such gravitational collision with the sun were left revolving around the sun in elliptical orbits.
As their centers lacked the high energy and pressure as in the sun, the fusion process could not ignite there and they failed to become stars. Instead, they ended up as far more useful—and potentially habitable—chunks of mass in the space: the planets.
There are now only eight planets revolving around sun because as billions of the masses kept hurtling in the space around sun, most collided and coalesced with one another. Eventually, smaller masses around those planets—like the moon around earth—ended up revolving around them instead of colliding with them.
The bodies which failed to collide with or revolve around planets inhabit our solar system as the asteroids and are concentrated in certain asteroid belts around the sun.
This is how the present day solar system was born.
[1] https://www.manchester.ac.uk/discover/news/manchester-scientists-contribute-to-antimatter-discovery-at-cern/
[i] https://solarsystem.nasa.gov/solar-system/our-solar-system/in-depth/
Intrigued by the content, kudos to you sir.