The yuga science appears to be first codified in India by the great sages of the hindu faith. It has been explained by many different sages and hindu scientists for thousands and thousands of years. Some of these folks hypothesized that the yugas entailed hundreds of thousands of years within the grand cycle, but this has been attributed to a misunderstanding of what was meant in the writings known as the Vedas.
I won’t go into depth on this history of the differing theories of what are the appropriate lengths of the yugas. I believe the theory put forth by Swami Sri Yukteswar is the most rational theory advanced to date. He gives a very succinct narrative of his theory in the beginning of his incredible treatise “Darsanam Sanatana” or “The Holy Science”, written around 1893. I highly recommend reading this book.
Sri Yukteswar puts forth his theory that the Yuga system involves an approximate 24,000 year cycle that repeats endlessly. One half of the cycle, 12,000 years, is a descending arc and one half, 12,000 years, is an ascending arc. They feed each other. One cannot happen without the other. Think of the Chinese symbol Yin-Yang. Each side of the symbol cannot exist without the other and they are feeding off of each other endlessly. Positive-Negative, black-white. The Law of Duality, for each there is an opposite. Hence, you have a descending arc and you have an ascending arc in the yuga cycle. Think of the descending arc as the negative side, the side of darkness. The ascending arc is the positive side, the side of light.
During the ascending arc, human consciousness is in an upward mobility or increasing in capacity, or what was described by Sri Yukteswar as mental dharma. So it would be supposed that during the descending arc, mankind’s mental dharma is the opposite, decreasing or in a downward mobility. Man’s capacity to understand himself and his place in this solar system during the descending arc is restrictive. As he once again starts the ascending cycle, his capacity to understand himself and his place increases. It is a repeating and continuing cycle, never ending so long as the solar system is in existence. Think about how the motions of this earth effects how you feel physically and you can begin to understand how the motions of the yugas effects mankind in a mental way or in a consciousness way.
Each arc of the yuga cycle is further broken down into four smaller cycles: the Kali Yuga, Dwapara Yuga, Treta Yuga and Satya Yuga. The 24,000 year cycle is called the Maha Yuga (or the great year as was called by Plato). Each of the yugas lasts for the following approximate number of years: Kali Yuga, 1200 years; Dwapara Yuga, 2400 years; Treta Yuga, 3600 years; and the Satya Yuga, 4800 years. This is the same whether the great year is descending or ascending. So the cycle of the Maha Yuga ascends from Kali Yuga to Dwapara Yuga to Treta Yuga to Satya Yuga then begins to descend through Satya Yuga to Treta Yuga to Dwapara Yuga to Kali Yuga. So you have a double time of the Kali and Satya Yugas during the transition periods from ascending to descending and descending to ascending. Each of these periods have transition times associated with them when mankinds mental dharma is transitioning from one phase into the next. It’s easier to visualize in a diagram:
The Yuga Science is the machinery of the universe. It is the mechanism that operates the universe and it all relates to reincarnation and karma. More on this to come.