“What seest thou else in the dark backward and abysm of time?” – William Shakespeare
Time is a component quantity of our daily lives. It is symbolic of the indefinite progress of existence, and events that are generally considered to occur in an apparently irreversible sequence from the past, to the present, and onto the future.
The concept of time has been central to the growth, and evolution of human civilizations. It has also served as an important facet of knowledge that has been studied to a great effect in religion, philosophy, and science. But, to this day, an absolute definition of time still evades scholars.
In The Dragons of Eden, Sagan does not extend his arguments toward an extensive discussion on the concept of time, but rather focuses on its use as a metaphor to describe humanity’s place in the cosmos. To infer the future, it is necessary for us to understand our origins. This is the basis of Sagan’s approach.
Now, it is argued that the predecessors of modern-day human beings, the Homo sapiens¸ evolved somewhere between 250,000, and 400,000 years ago. This number pales in comparison to the appearance of the first primitive humans, such as the Australopithecines, which happened somewhere between 8-9 million years ago. But, even these events, are preceded by an even greater “vista of time” reaching far back into the history of our planet, the solar system, and the universe. Very little is known about these periods of time, and even with the numbers mentioned earlier, we still struggle to grasp the immensity of these time intervals (Figure 1).
Nevertheless, science has found success in the establishment of specific methods that have allowed us to date events from the remote past, such as geological stratification (Figure 2), and radioactive dating (Figure 3).
These two methods have provided information on archaeological, paleontological, and geological events. Astrophysical theory has provided for the same on a grander scale involving the dating of stars, planetary surfaces, galaxies, and the even the age of the universe (Sagan states this to be 15 billion years old, though recent results from the Wilkinson Microwave Anisotropy Probe (WMAP) puts the number somewhere at 14 billion years old). The earliest event known in record is called the Big Bang, an intense explosion from the universe is said to have formed, but rather than a beginning, the Big Bang is generally considered to be a discontinuity in time where the earlier history of the universe was destroyed.
To put this further into perspective, Sagan introduces the Cosmic Calendar, where he compresses the 14-billion-year-old chronology of the universe, into the span of a single earth year. In this manner, one billion years of Earth history is the equivalent of twenty-four days of our cosmic year, and one second of the cosmic year is the same as 475 real revolutions of the Earth about the sun. The Cosmic Calendar is a humbling account of humanity’s place in the universe, with all our recorded history occupying the last few seconds of December 31.
Though a short chapter, Sagan’s use of the Cosmic Calendar is quite analogous to a common argument used in astronomy to provide a picture of our place in the universe (Figure 4).
While the major premise of Sagan’s book focuses on discussions on the evolution of human intelligence, this introductory chapter is a necessary prelude that helps to symbolize the significance of the subject matter. While it may be true that humanity occupies an insignificant instance in the face of cosmic time, we are now embarking on a new cosmic year, one which is highly dependent on our ability as a species to come together, use our wisdom, and unique sensitivity to the world for our survival, and a greater future.
- Sagan, Carl. The Dragons of Eden: Speculations On The Evolution of Human Intelligence. Ballantine Books, 1977.
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