The Abyss of Time
“The mind seemed to grow giddy by looking so far into the abyss of time.”
“We find no vestige of a beginning, no prospect of an end”
Perhaps no physical phenomenon befuddles the human mind as much as time. Whether the result of unknown properties or the inability of our senses to perceive the reality of the universe, we simply cannot fully grasp this concept.
Time seems to move in only one direction, for which we have developed a meaning of past, present, and future. Is this one-way street the essence of time or are our bodies unable to process it in any other way? Albert Einstein showed us that time is relative, not absolute. In some ways and in some models time functions more like a fourth dimension than a neverending race into the future. Relativity seems to imply moving backward in time is theoretically possible. Time is so strange that the scientific definition relies on the measurement of the phenomenon itself: “time is what a clock reads.” In the relativistic universe, clocks don’t even measure time the same way, depending on one’s frame of reference and speed. Countless physicists, philosophers, theologians, and poets have mused on the subject and we don’t seem close to solving the conundrums.
Even in one frame of reference – the surface of Earth – we have a hard time handling time (1). Einstein once quipped, “Put your hand on a hot stove for a minute, and it seems like an hour. Sit with a pretty girl for an hour, and it seems like a minute.” Currently, my family is learning to amend the quote a bit: “Sit with a toddler and an infant for a minute and it feels like a day. Sit with your children for a year and it seems like a week.” In other words, sometimes the days drag, while the weeks, months, and years fly. I suspect we experience time differently than the strict clock reading as a result of the evolution of our brains. We sense things based on the hardware we have, there’s no way around that.
Because of this fact, however, we tend to view most things through the selfish frame of humanity. Including the age of our home.
How old is Earth?
The answer to that question varied greatly, depending on when one lived. Aristotle, in Physics, argued for the eternity of the world. The Roman poet Lucretius believed the planet to be much newer than eternal. No historical record preceded the Trojan War, so the globe must be about that old. Philosophers and theologians of the middle of the second millennium used the Bible to date the beginning of Earth. In 1654, Archbishop James Ussher of Ireland worked out the math, placing the genesis of our planet in the year 4004 BC. These teleological views might seem outlandish, but big concepts are difficult to grok when we work with limited perspective; even if Aristotle is ultimately proved incorrect, he seemed to be ahead of his time (2), thinking beyond the human-centric viewpoint.
In the late 17th century, scientists started to question the acceptance that the age of the planet is 6,000 years. Danish scientists and Catholic bishop Nicolas Steno discovered the stratification of rocks and the fossils within them in the 1660s. English scientist Robert Hooke, who coined the term “cell,” predicted the fossil record would one day show a history that stretched even beyond the building of the pyramids. Interestingly, according to Scientific American, the development of canals in the 18th century unlocked the ability for scientists to discover rock strata could extend for massive distances. All these developments pushed us toward the capacity to seriously question the formation and age of Earth.
One specific location, however, provided specific inspiration to move from speculation to hard geology.
The Scottish scientist James Hutton is often called the Father of Modern Geology. In 1788, he took a trip with mathematician John Playfair and geophysicist James Hall to a point on the Caledonian coast, called Siccar Point. There, Hutton showed his colleagues proof of what he had discovered in the preceding years.
Based on the work of Steno and others, scientists had begun to understand that sedimentary rocks were formed in and with water, largely on ocean beds. The chemistry of these rocks alone suggested a far older Earth than most people previously believed, but Hutton noted other oddities in these layers. Our planet isn’t formed from nice, even layers of rock. Sometimes rock layers jut straight up, forming cliffs or mountains. Since all the evidence pointed to horizontal bedding, how did these rocks end up this way? Further, sometimes rock layers next to each other vary drastically. Does the deposition of sediment simply change instantaneously, leading to a switch in appearance? Hutton envisioned a new paradigm, one which led to the revolution of geology. With his new approach, several of the key processes and terms in geology came into being.
Hutton believed forces under the surface vastly influenced rocks. Igneous rocks, he surmised, formed somewhere below and intruded above. This notion is called Plutonism. He theorized that sedimentary rocks formed in an endless cycle under the sea. Uplifts and intrusions from below the surface would warp and twist these layers, causing the verticality we see. To top it all off, he realized that any switch from one layer to the next represented something far more radical than just a switch in sedimentary chemistry.
Hutton had thrust three major tenets of modern geology into the inverted-lithosphere: uniformitarianism, unconformity, and Plutonism.
In short, the Uniformity Principle states that the natural laws that operate today are the same ones that operated in the past. In geology, uniformitarianism means rocks formed ages ago in the same way they do today, allowing us to extrapolate the history of the planet. Unconformities are the surfaces that differentiate rock layers. Think about the Grand Canyon. Each time you see a different color, where the rocks meet is an unconformity. These are the different eras of Earth’s past next to each other.
Combined, these notions not only explain how we get the formations we see, but also led to a profound expansion of our notion of time.
Hutton realized the unconformities did not represent instantaneous points on a historical spectrum. In fact, they represented the opposite, a lack of history. Each time one type of rock abuts another indicates something missing. In the case of geology, that something is often millions and millions of years. An unconformity means the conditions that produced the older rock changed, perhaps a cataclysmic geological event or the lowering of ocean levels. Maybe millions of years later, water once again covered the area, which allowed for another layer of sedimentation to begin to accumulate. No matter how an unconformity occurred, it represented the loss of millions of years of fossils and any trace of the region for that period.
James Hutton, born into an era where humans believed the Earth might be 6,000 years old, had understood this timeframe to be woefully short. Instead of millennia, he stared at rocks and attempted to fathom millions or billions of years.
As they peered at Siccar Point, John Playfair glimpsed what he later called the abyss of time. The word “abyss” comes from the ancient Greek abyssos, meaning “bottomless” or “unfathomable.” Even today, humans lack the ability to truly understand what millions or billions mean. Imagine attempting to move from a starting point of 6,000 years to these scales. Geology’s time had arrived (3).
In 1981, John McPhee coined the term deep time to represent the unfathomable essence of geological time. Scientists now believe the age of the Earth to be 4.55 billion years old. Aristotle might not be right that the planet is eternal, but he seems a lot closer to correct than those who thought we’re only six millennia into planethood. Of course, the mathematicians in the crowd will remind me that 6,000 is closer to 4.55 billion than 4.55 billion is to infinity (eternity?). To most people in the 17th century, 4 billion might as well be eternal. To most of us today, this concept continues to hold.
McPhee used a metaphor to illustrate deep time. If the history of the Earth is the old English measure of a yard – the king’s nose to the tip of his hand – one stroke of a nail file on the middle finger wipes out humanity.
I find it hard to conceptualize the lives of my grandparents, let alone any ancestors beyond that point. All the things in modern history that seem ancient are mere blips to the rocks on which we stand, lesser than the ants we overstep on a sidewalk or the leaf we see falling are to our lives. On top of it all, Earth is just one-third as old as the observable universe.
These minutes with pretty girls are already short enough. Comparing them to the abyss of time is a rather sobering exercise.
Further Reading and Exploration
How Science Figured Out the Age of Earth – Scientific American
“We find no vestige of a beginning, no prospect of an end” – National Geographic
The Abyss of Time – NASA
The man who discovered the ‘abyss of time’ – BBC