Cosmic Evolution and Impermanence
The cosmological theory that
best describes the current observations of the universe is that of the Big
Bang. It is now believed that the
universe began its existence some 15 billion years ago with an enormous
explosion from an initial state that was extremely tiny, hot and dense and that
spawned space and time. Since then, there has been a relentless ascent towards
increasing complexity. Beginning with a
vacuum filled with energy, through the primordial soup of elementary particles,
the universe has woven an immense cosmic tapestry composed of hundreds of
billions of galaxies, each made in turn of hundreds of billions stars. In one
of these galaxies named “Milky Way”, on a planet near a star about 2/3 of the
way from the Galactic center toward the edge, humanity appeared, capable of
marveling at the beauty and harmony of the cosmos and of asking questions about
it.
One of the most remarkable
changes of paradigm that has occurred with the advent of the big bang theory is
that the universe has acquired a historical dimension. We can now speak of the
history of the universe, with a beginning and an end, with a past, present and
future. That the universe has a history was not always accepted. Some 24
centuries ago, the Greek philosopher Aristotle thought that the Heavens,
because they were perfect, had to be unchanging and eternal in contrast to the
changeable and imperfect world of the Earth and the Moon. Newton’s universe in the 17th century was
static, unchanging and devoid of history. As late as the 1950s, the Steady
State Theory, which says that the universe is on the average unchanging both in
space and time, was considered a serious rival to the Big Bang Theory. The Big Bang Theory thus introduces the
fundamental idea of cosmic evolution.
Stars are born, live their lives, and die. In the course of their death
throes, the massive stars eject gas that shall serve as seed for the birth of a
new generation of stars. Those life and death cycles last from a few million
years to several billion years. The universe itself may go through cycles of
births and deaths, Big Bangs followed by Big Crunches, although it is not yet
clear if the universe contains enough dark matter for its gravity to halt its
present motion of expansion and reverse it.
The idea of ceaseless change, of constant evolution due to the
never-ending chain of causes and effects, is also central to Buddhism. It is
called “impermanence.”
Contributed by: Trinh Xuan Thuan
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