cosmos and origins
What is the Vedic model of the three worlds (Triloka) and how do they relate to each other?
The three worlds
The three worlds are Bhuloka, Bhuvarloka, and Svarloka. Bhuloka is the earth, the physical world we live in. Bhuvarloka is the middle space between earth and sky, sometimes described as the realm of breath, life force, and the ancestors. Svarloka is the heavenly realm above, associated with light, the gods, and the sun. Together they cover all of existence as the Vedic tradition understood it. These three are sometimes called the Triloka, meaning simply the three worlds.
The Gayatri mantra and the three words
The three worlds appear directly in the Gayatri mantra as the words Bhur, Bhuvah, and Svah. These three words are called the Vyahritis, a Sanskrit term meaning utterances or declarations. In ritual use, saying them is understood as invoking all three levels of existence at once. The mantra is addressed to the sun as the source of light and wisdom, and the Vyahritis place that invocation across the whole of reality, not just the physical sky. This is why the Gayatri is treated as a complete and powerful utterance in the tradition.
How the model grew over time
The three-world model is among the oldest in the tradition. Over time, Puranic texts expanded it. Seven lokas became a common number, and some texts describe as many as fourteen, with realms both above and below the earth. The three-world model did not disappear, though. It stayed in ritual use and in the Gayatri mantra while the fuller Puranic maps added detail for cosmological storytelling and for describing where different beings, ancestors, and divine figures dwell.
The body as a small cosmos
One idea found in the tradition is that the three worlds are not only outside but also inside the human being. Bhuloka is linked to the physical body. Bhuvarloka is linked to the breath and the vital forces. Svarloka is linked to the mind or the higher faculties. This way of thinking, sometimes called microcosm-macrocosm thinking, holds that the structure of the universe repeats itself in the structure of a person. Ritual and meditation can then be understood as working on both levels at once.
How people encounter this today
Most Hindus today meet the Triloka through the Gayatri mantra rather than through cosmological study. The three Vyahritis are chanted daily by many people without necessarily thinking through the full cosmological meaning. Scholars and practitioners interested in Vedic ritual or Vedanta explore the layered meanings more closely. The model also comes up in yoga and meditation traditions that use the body-cosmos parallel. How much weight any of these meanings carries varies widely from person to person and tradition to tradition.