Measure of Eternity

 Time is ubiquitous, felt by all, yet unfathomably mysterious. In an earlier post I wrote of its enigmatic nature. Not only its nature, even its scale is beyond the grasp of human mind. 

Smallest quantity of time measurable theoretically is 10^–43seond, i.e., one part of a second divided into 10⁴³ parts (ten followed by 42 zeroes). This scale does not pertain only to the realm of theoretical physics. Our universe changed immensely within these time intervals at its inception. 10^–32 second after Big Bang, universe had increased by a factor of 10⁷⁸. This increase in volume is like the expansion of half a molecule of DNA into a space of 10.6 light years. One light year is the distance light travels in a year, which is 9 trillion kilometres. That is a 9 with 12 zeroes behind it.

At the other end of its scale time is equally baffling. Life on earth began about 3.8 billion years ago. For us, billion is just a figure, one followed by nine zeroes. To picture the vastness billion encloses, simple analogies help. A billion seconds ago it was 1980, a billion minutes ago A.D. 100, a billion hours ago Homo Sapiens had recently evolved.

Expanse of geological time and size of universe, seen in the context of human life, teach us humility. Compress earth’s history of about four billion years in 24 hours, the present moment being just past midnight. In this analogy Earth forms at 12.00 A.M., the previous night. Life begins quite early, at about 4am. Dinosaurs will rule the earth from 10:40 P.M. to 11:40 P.M. Human ancestors will split from other hominids only two minutes to midnight and modern humans will arrive only as the clock strikes midnight.

An analogy of geological time that never fails to give me goose bumps is this. Fling your arms wide. Tip of the left finger represents the origin of life and the tip of the right, the present moment. Well beyond the right shoulder all the way across your midline, life is represented by bacteria. Animal life appears near your right elbow. Dinosaurs appear in the middle of the right palm and go extinct near the last joint of the fingers. History of Homo Sapiens and our immediate predecessor, Homo Erectus is contained in the thickness of one nail-clipping. And one light stroke of a nail-file will wipe away the complete recorded history; The great Pharoah’s might that built imperishable Pyramids, The everlasting dynasties of ancient China, Marvellously planned towns of Harappa and Mohenjo-Daro, Veds, Purans, Mahabharat and Ramayan, The Greek philosophy and the Roman gods, Origins of Buddhism, Hinduism, Judaism, Leonardo-da-Vinci’s enigmatically smiling Madonna, Michelangelo’s ethereally beautiful David, Protectors of the universe-the unconquerable Mughal emperors, Sonnets of Shakespeare, The boundless British empire on whom Sun never set, Einstein’s relativity, Novels of Tolstoy, Stories of Chekhov, Nazms of Faiz, Ghazals of Ghalib, The city of Joy and The unending slums of Bombay. All will be blown away as the file rubs the edge of a nail.

If this is the truth of our existence, one wonders, whence cometh the hubris of man; belief that the universe was created for its most evolved species, a moderate sized bipedal-ape with a self-indulgent mind.

Every religion has dealt with the mystery of time in a unique way. Biblical time is linear. It runs one way. Man is born, lives his life and ends it on the day of Judgement. After this there is eternal joy in Heaven or torment in Hell. There is no turning back. Bible also gives an accurate date to the origin of the universe; 4004 B.C. Biblical God created the universe and all life in it in six days.

In Hindu theology, time, Kaal, is measurelessly grand and cyclical. Each cycle has three components: Srishti, creation; Stithi, continuation; and Laya, dissolution. After a brief respite cycle begins all over again. Time is illusory. In god’s consciousness there is no division of time. There is only one present moment; one continuous, indivisible existence. Time is manifestation of God. God is timeless. Time is relative and ceases to exist in the Absolute. Hindu belief also defines time in humungous proportions that rival the geological scale. Cosmic time is divided in Kalpas, a day and night in the time and space of Brahma. It equals 8.64 billion years. Lifespan of Brahma is hundred Brahma years, i.e., 311.04 trillion years.

Scale of time in our lives seems to be a different attribute when compared to the geological time. These appear to be two different parameters, not of the same world. One can neither perceive the gigantic expanse of geological eons, nor can our clocks measure it. 

Clocks we use in our daily lives exploit the regularity of a natural process to measure time: Flow of water in or out of a container in a water clock; Burning of wax in candle clock; Flow of sand in an hourglass; Rotation of earth in sundial; Swivelling of a hairspring in a timepiece; Swinging of pendulum in a grandfather’s clock; Oscillation of a crystal in quartz clock; Resonation of atoms in atomic clock.

Science is sure of the dates of major events in the history of universe and life on earth, however beyond our imagination these may be. Some of these are: age of earth, origin of life, origin of various species, migration of human ancestors out of Africa, creation of continents by plate tectonics, rise and fall of various empires, etc. What are the clocks science employs to measure this seemingly unmeasurable time? Fortunately, nature has many such timekeepers ticking in its amazing structure. Once again, I am left breathless at science’s ability to prise open nature's secrets by application of simple laws that on face appear utterly alien to the use they are put to.

Science of counting tree-rings, Dendrochronology, employs the variable growth of trees during favourable and inclement seasons, seen as rings in tree's girth. This pattern is not unlike a barcode used today. Matching the older ring patterns of newly felled trees - whose date of death is known - to the younger ring pattern of an old wood and then counting the rings backwards, age of the wood can be ascertained. Daisy chaining backwards from this older ring pattern to even older woods, one can estimate the age of trees that were alive many millennia back. But you need old petrified wood for the study. This is scarce. Dendrochronology can take us back only 11,500 years.

Geological processes and biological evolution cannot be measured even in thousands of years. These span time scales of tens of millions, hundreds of millions or billions of years. 

Buried in earth’s landscape are radioactive clocks that enable us to measure these gargantuan time periods. Radioactive isotopes decay at a constant rate. This is measured as isotope’s half-life; Time interval in which half the initial mass of isotope decays. Half-life of various isotopes varies from 49 billion years of rubidium-87 to 3.3 milliseconds of fermium-244. The most useful for evolutionary studies is potassium-40, which decays into argon-40 with a half-life of 1.26 billion years, hence the name potassium-argon clock.

Radioactive isotopes are found in igneous rocks. These are rocks formed from molten lava or magma. After formation of a rock, the quantity of isotope in it (e.g., potassium-40) decreases steadily and that of the decay-product (e.g., argon-40) increases. Thus, ratio of argon-40 to potassium-40 in a sample of igneous rock can tell us the age of the rock, i.e., when it was formed. Beauty of this clock is that age doesn’t depend on the absolute quantity of potassium-40 contained in the rock initially, only on the present ratio of argon-40 to potassium-40. Fossils are found in sedimentary rocks which have igneous formations embedded within. Age of these igneous rocks tells us when a particular organism fossilised in the sedimentary rock was alive.

Carbon-14 dating is another ingenious tool to date archaeological specimens. Carbon is the most basic building block of all life on earth. It is required for the formation of complex molecules like DNA and proteins.  It is found in the atmosphere as carbon dioxide, i.e., CO₂. Through photosynthesis by plants, it enters food chain. Most carbon in the atmosphere is carbon-12. About one in a trillion atoms is carbon-14. This is the ratio of carbon-12 to carbon-14 in a living organism too, as long as it continues to be a link in the Carbon-cycle. On its death this chain is disrupted. Carbon-14 contained in the dead body slowly converts to nitrogen-14 and the ratio of carbon-14 to carbon-12 decreases. Half-life of carbon-14 is 5760 years. Thus, analysis of the proportion of carbon-14 to carbon-12 in a dead organism can reveal the time of its death. Carbon-14 dating is useful for dates up to 50,000 years back.

The most famous riddle solved by carbon-14 dating in recent times is the case of the Shroud of Turin. A piece of cloth preserved in Turin since 1578, allegedly has imprinted on it an image of a bearded, crucified man. Thus, the shroud was supposed to hail from the time of Jesus. In 1988, laboratories at Oxford, Zurich, and Tucson performed carbon dating on a tiny piece of this cloth. All arrived at a date of origin of the shroud in the 13th century within accepted margins of error. Vatican found ingenious ways to circumvent this demystification of the myth and continues to encourage believers to revere the shroud as an “icon of a man scourged and crucified”.

Today I am drunk on the wine of scientific rigour – the breath-taking power of human mind which teases out truth from the entangled web of observations – and will steer away from the debate on Fact vs Fiction.

Molecular clock is another important timekeeper in nature that helps evolutionary science. Gene mutation is a known phenomenon. A mutation which affects the body of the organism in some way is extremely rare. Such mutations are preserved, if they benefit the organism or they perish, if they are harmful. 95% of our genome has absolutely no function. A mutation in these genes is not translated into any effect in the body. There are certain genes which code for proteins that are absolutely vital for life. A mutation in these genes too does not affect a change in its function. Thus, nature would not read these mutations and the gene will continue to code for the same protein. But a molecular geneticist can read them. These are called Neutral mutations, as they do not affect the function of the gene.

Each gene has a characteristic rate of turning up new Neutral mutation. Histone genes turn up a mutation once in a billion years, Cytochrome C genes once in a million years and Haemoglobin genes once in ten million years. Molecular clock helps evolutionary biologist decide when two species split apart in their evolutionary history. If a gene common to two species, accumulated Neutral mutations at a rate of 1% per million years, then a difference of 2% in the genes in two species will imply they separated ways about a million years ago. Thus, it is known today that ancestors of humans and chimps, our nearest cousins in the animal world today, separated about 5-6 million ago.

Theologians will argue forever about time’s nature: whether it is linear or cyclical; whether God created the universe in six days and rested on the seventh or God unendingly creates and destroys worlds. 

Einstein's Gods were the infallible laws of nature. All his life he strove to read the hidden meaning behind nature's manifest phenomena. 'Subtle is the Lord, malicious he is not', he would say when confronted with some seemingly intractable riddle in nature.

Time leaves its indelible footprints in the universe with which it was born in a very distant past. Effort of science to discover these imprints and unravel their meaning is as thrilling a journey as are the intrigues of this most unique dimension of our universe and our lives - The immortal, eternal Time.