Dr Irengbam Mohendra Singh
Nothing existed forever. Nat “King” Cole set a gold standard for smooth jazz singing with his baritone voice in his “Unforgettable/Unforgettable/that’s what you are … in 1951. All the evidence seems to indicate, that the universe has not existed forever. It had a beginning, about 15 billion years ago.
Stephen Hawking, in a lecture in Japan, said “the universe has not existed forever. Rather, the universe, and time itself, had a beginning in the Big Bang, about 15 billion years ago. The beginning of real time, would have been a singularity.” Singularity in physics, means a one-dimensional point that contains a huge mass in an infinitely small space, where density and gravity becomes infinite and space-time curves infinitely, and where the laws of physics do not operate.
Hawking continued: “time must have a beginning if Einstein’s General Theory of relativity is correct. But one might raise the question, of whether General Relativity really is correct. We know that General Relativity cannot be quite correct on very small distances though It certainly agrees with all the observational tests that have been carried out over large distances.”
The beginning of the Universe as the Big Bang is now agreed by most scientists, but what was before the Big Bang is still unanswered. The creation of the Universe after the Big Bang explosion is more or less explained by physicists. It happened very quickly in the first few fractions of a second, when the universe was filled with an intensely “hot soup of energy and particles” that formed the matter.
The Big Bang theory is the only theory that can explain the presence of Cosmic Microwave Background Radiation (CMBR). Inversely, it support the Big Bang, and the theory of ‘cosmic inflation’ – the theory that universe expanded much faster than the speed of light, just in a few tiny fractions of a second after the Big Bang.
How the expanding Universe began to accelerate after the Big Bang was captured by the Hubble telescope. Theoretically, we can conceptualise that if we stop the expanding universe at a single point of time and rewind, it will merge into an infinitely small point, smaller than an atom.
With modern telescopes, scientists can view objects many billions of light years away, close to the time of the Big Bang. They can work out how the Big Bang explosion occurred mathematically, 15 billion years ago, by calculation from the size of the universe and the speed with which it is expanding. They can see how ‘galaxies’ – those fuzzy patches in the sky, move away at very high speeds, because of an effect called “red-shift”, a concept for astronomers to mean that the light is seen as ‘shifted’ towards the red part of the spectrum.
In 1964, two American radio astronomers, Arno Penzias and Robert Wilson discovered leftover and cooled down radiation from early in the history of Universe. For this they won Nobel prize in physics in 1978. These radiations are coming uniformly from every direction in space, which scientists interpret to be the remnant of the incredibly bright light after the Big Bang, and which began to stretch as it expanded. This is now known as microwaves. A microwave telescope can see this ancient light that fills the whole sky with a glow, day and night.
CMBR is the oldest and coldest light in the universe. It shines primarily in the microwave portion of the electromagnetic spectrum and is invisible to the naked eye. Microwaves are a form of electromagnetic radiation, smaller than radio waves but bigger than infrared waves. They are good for transmitting information, such as mobile phone calls, radio and television broadcasting, and for conducting thermal energy to heat food quickly (microwave ovens).
Yet, fundamental physicists are still unable to solve the mystery of how this infinitesimally small, dense and hot point took the initial form as it did. But they can explain what happened after the Big Bang. A British physicist Prof Brian Cox describes how, as a consequence of the Big Bang, subatomic and atomic particles, and matter came to exist in our universe. In modern physics, ‘particles’ are not like grains of rice as we perceived but like ‘ripples’ in the quantum field.
Cox begins with a few theoretically motivated events in modern physics as to how such building blocks of our universe, which are fundamentally hydrogen and helium emerged. The Higgs boson, nick-named ‘God particle’, discovered at CERN’s Large Hadron Collider in Geneva (cf. Author’s book Points to Ponder p319) further seals the Big Bang theory. In quantum physics, it was Higgs-like particles that sparked the cosmic explosion. Everything in the universe owes its existence to the Higgs boson.
Cox introduces the first milestone in the formation of the universe after the Big Bang, known as the ‘Planck Era’. This is the period occurring mathematically, in 10-43 (10 raised to the power 43) seconds after the Big Bang. Written in full, the number has 42 decimal places: 0.000000000000000000000000000000000000000001. Scientists could count the time, simply because it’s related to the strength of the gravitational force. At that time, the four fundamental forces of nature that we know ie gravity, electromagnetism, and the strong and weak nuclear forces, were one and the same force, known as “superforce”. There was no matter at this stage, only energy and superforce. This is what physicists call a ‘very symmetrical situation’.
Symmetry is the most powerful tool of theoretical physics, as it has become evident that all laws of nature originate in symmetries. The physical laws remain valid at all places and times in the universe, and particles such as atoms remain unchanged after being subjected to a variety of symmetry transformations.
As the universe rapidly expanded and cooled, it underwent a series of spontaneous ‘symmetry-breaking’ events. This symmetry-breaking is a phenomenon, which usually brings a system from symmetric but disorderly state into one or more definite states (PW Anderson 1972). It’s called the Planck Era as mentioned above. The end of the Planck Era saw gravity separate form other forces of nature, and so perfect symmetry was broken.
After the Plank Era, another symmetry-breaking event occurred, which ended at 10-36 seconds, known as the ‘Grand Unification Era’. In this era, the ‘strong nuclear force’ that sticks the quarks together inside protons and neutrons, separated from the other fundamental forces. It’s followed by the ‘Inflationary Era’ when the Universe had a violent expansion known as ‘inflation’, by a factor of 10-26 seconds ie 100 million million times in an unimaginably small space of time, finishing in 10-32 seconds. This was when subatomic particles entered the Universe and none of them had any mass at all.
Physicists are now entering into an era when they are recreating and observing such a symmetry-breaking event at CERN’s Large Hadron Collider. This is the great symmetry-breaking event that occurred 10-11 after the Big Bang. It’s called the “electroweak symmetry-breaking event”. At this point, the final two forces of nature – electromagnetism and the weak nuclear force are separated. During this process the subatomic building blocks of everything, such as quarks and electrons acquired mass. The most popular theory of this mechanism is called the Higgs mechanism.
From this point onwards, physicists can know pretty much exactly what happened to the Universe by means of experiments at particle accelerators. They believe the emergence of familiar particles and forces we see in the Universe today happened because of a series of symmetry-breaking events, which began way back at the end of the Planck Era.
The concept of spontaneous symmetry-breaking in the early Planck Era of the Universe, according to Cox, is the same as transitions from water vapour to liquid water to complex snowflakes that hide the underlying simple symmetry of oxygen and hydrogen atoms, as I wrote in a previous article about snowflakes. The complex patterns of the Universe that emerged without prompting, due to falling temperature, obscure the underlying symmetry of the Universe in its initial state.
When the universe had cooled enough, the quarks appeared approximately 10″12 seconds after the Big Bang. It was when the preceding electroweak epoch ended as the electroweak interaction separated into the weak interaction and electromagnetism. The quarks began to glue together with by the string nuclear force to form protons and neutrons, known as hadrons, the building blocks of elements. Protons are made of 3 quarks. Quarks along with leptons, such electrons. muons or neutrinos are fundamental point-particles and are themselves made of energy.
So, after only a millionth of a second in the life of the universe, the first and the simplest chemical element hydrogen consisting of a single proton made its appearance. After three minutes the universe was cold enough for the two protons and one or two neutrons to stick together to form the nucleus of helium, second-simplest chemical element. There were also very small amounts of lithium with three protons, and beryllium with four protons.
After three minutes the universe had the four distinct forces we know today: gravity, the strong and weak nuclear forces, and electromagnetism. The universe was then composed of roughly 75% hydrogen (by mass) and 25% helium. After that epoch no elements were created for millions of years. Today the whole universe is made up of 92 elements.
(The writer is based in the UK: Email:firstname.lastname@example.org. Website:www.drimsingh.co.uk)
Dr Irengbam Mohendra Singh