In Hindu philosophy, the existence of the world is divided into four Yugas (ages):

1. Satya Yuga or Krita Yuga
2. Treta Yuga
3. Dwapara Yuga
4. Kali Yuga

According to the rishis of ancient India, the world goes through a continuous cycle of these ages. Each ascending phase of the cycle from Kali Yuga to Satya Yuga is followed by a descending phase back to Kali Yuga, then another ascending phase and so on.

1. In the lowest phase, Kali Yuga, most people are aware only of the physical aspect of existence, the predominant emphasis of living is material survival, and power is mostly in the hands of men. People's relationship with the spiritual is governed predominantly by superstition and by authority.
2. In the second phase, Dwapara Yuga, science flourishes, people experience the spiritual in terms of subtle energies and rational choices, inventions are abundant, particularly those that dissolve the illusion of distance (between people and between things), and power is mostly in the hands of women.
3. The third phase,Treta Yuga, is the mental age, magnetism is harnessed, men are in power, and inventions dissolve the illusion of time. (Inventions are characteristic of both Dwapara and Treta yugas.) Lord Rama is said to have lived during this Yuga.
4. In the fourth phase, the great majority of the people can experience spirituality by direct intuitive realization of truth. The veil between the material and the transcendent realms becomes almost see-through, as the illusion of different densities of vibration is dissolved. Power is predominantly in the hands of women. Satya Yuga is also called the Golden Age.

Temples, wars, and writing are hallmarks of Dwapara and Kali yugas. In the higher ages (Treta and Satya), writing is unnecessary because people communicate directly by thought; temples are unnecessary because people feel the omnipresence of God; wars are rare but they do occur and because people have command of vibration bombs they can be extremely damaging.

According to Swami Sri Yukteswar, the descending phase of Satya Yuga lasts 4800 years. That of Treta Yuga lasts 3600 years. That of Dwapara Yuga lasts 2400 years. That of Kali Yuga lasts 1200 years. The ascending phase of Kali Yuga then begins, also lasting 1200 years; and so on. The ascending phase of Kali Yuga began in September of 499AD. Since September 1699, we have been in the ascending phase of Dwapara Yuga.

This is not the traditional schedule of mainstream Hinduism, which holds that the yugas are much longer, and that we are in the long Kali Yuga today. For example, many followers of Sri Satya Sai Baba agree that Lord Rama was an avatar of Treta Yuga and Lord Krishna an avatar of Dwapara Yuga, but say we are still in Kali Yuga today.

1. Satya Yuga or Krita Yuga - 1,728,000 years
2. Treta Yuga - 1,296,000 years
3. Dwapar Yuga - 864,000 years
4. Kali Yuga - 432,000 years

Traditionally, upon conclusion of 71 circuits of this cycle, (1, 728,000 years) there is a period equally long during which the world is inundated; then the cycle begins again.

According to Yukteswar (in The Holy Science), the traditional view is based on a misunderstanding. He says that at the end of the last descending Dwapara Yuga (about 700 BC) "Maharaja Yudhisthara, noticing the appearance of the dark Kali Yuga, made over his throne to his grandson [and]...together with all of his wise men...retired to the Himalaya Mountains...Thus there was none in the court...who could understand the principle of correctly accounting the ages of the several Yugas."

Nobody wanted to announce the bad news of the beginning of the descending Kali Yuga, so they just kept adding years to the Dwapara date (at that time 2400 Dwapara). By the deepest point of the Kali Yuga (around 500 BC) that made the date 3600. As the Kali began to ascend again, scholars of the time recognized that there was a mistake in the date (then being called 3600+ Kali, although their texts said Kali had only 1200 years). "By way of reconciliation, they fancied that 1200 years, the real age of Kali, were not the ordinary years of our earth, but were so many daiva years ("years of the gods"), consisting of 12 daiva months of 30 daiva days each, with each daiva day being equal to one ordinary solar year of our earth. Hence according to these men 1200 years of Kali Yuga must be equal to 432,000 years of our earth."

According to Yukteswar's book, written in 1894, our sun is part of a binary system, orbiting another star, with an orbital period of about 24,000 years. As our sun moves through this orbit it takes the whole solar system closer to and then further from some "grand center called 'Vishnunabhi', which is the seat of the creative power, 'Brahma', [which]...regulates...the mental virtue of the internal world."

Interestingly, Western astronomy in 1894 had no concept whatsoever of binary star systems; however, modern astronomy has recently recognized that the majority (half or more) of observable stars are part of multi-star gravitational/orbital systems (binary or more).

The "yuga" cycle corresponds to the phenomenon described as "precession of the equinoxes" whereby the positions of constellations shift across the horizon over a period of (if it continues at current rates) 25,600 years. The usual explanation for this is that it is due to precession, whereby Earth's poles wobble over time much like the motion of a toy top. However, according to some, the same observed phenomenon could be explained equally well (some say better) by elliptical motion of our solar system through space, such as would be caused by it orbiting (and being orbited by) a binary companion. (Such elliptical motion would cause the "precession" to vary in speed over time, resulting in a complete cycle of length very close to 24,000 years.)

Bibliography

• The Holy Science by Swami Sri Yukteswar. Published by Self-Realization Fellowship.
• 24,000 Year Yuga Calendar at http://www.GodTeacher.org
• http://www.binaryresearchinstitute.org
• http://www.thegreatyear.com

See also

• Metrics of time in Hinduism