Jayant Narlikar, the eminent Indian astrophysicist, passed away on May 20, 2025, leaving behind a rich legacy in theoretical physics. He is best known for co-developing the Hoyle-Narlikar Theory of Gravity, a groundbreaking model proposed in 1964 with British cosmologist Fred Hoyle. The theory sought to extend Albert Einstein’s General Theory of Relativity by introducing novel concepts that challenged the prevailing cosmological views of the time.
Background: Incorporating Mach’s Principle
At the heart of the Hoyle-Narlikar theory was an effort to incorporate Mach’s Principle, which suggests that the inertia of a body is determined by its interaction with the rest of the matter in the universe. While Einstein was inspired by this idea, he did not fully integrate it into his general relativity framework. Hoyle and Narlikar took a more literal approach, proposing that an object’s mass and inertia arise from its relationship with all other masses in the cosmos.
Key Concepts of the Theory
The theory posits that no object exists in isolation—each celestial body’s gravitational characteristics are influenced by all others. For example, the mass of the Earth is not a standalone property but is shaped by its interaction with the Sun and other cosmic entities. This interconnectedness implies that a universe devoid of matter is fundamentally unimaginable.
The Creation Field (C-field)
One of the most innovative elements of the Hoyle-Narlikar theory is the introduction of a Creation Field, or C-field. This hypothetical field is thought to produce negative energy, enabling the continuous creation of matter. The C-field supports the steady-state cosmological model, which asserts that the universe has no beginning or end and is eternally expanding—yet never thinning—because new matter is constantly being formed.
Steady-State Cosmology vs. Big Bang Theory
The steady-state theory stands in direct contrast to the Big Bang theory, which posits that the universe originated around 13.8 billion years ago in a singular, explosive event. According to Hoyle and Narlikar, if the universe is continuously expanding, it should become increasingly empty. To counter this, their theory suggests that the C-field continuously generates hydrogen atoms to maintain a uniform cosmic density.
Challenges and Legacy
The Hoyle-Narlikar theory faced significant setbacks following the 1965 discovery of the Cosmic Microwave Background (CMB) radiation, widely interpreted as the afterglow of the Big Bang. The CMB provided compelling evidence in support of the Big Bang model, leading to a decline in acceptance of the steady-state theory.
Despite this, the Hoyle-Narlikar theory remains influential for its bold attempt to integrate Mach’s Principle into gravity and for presenting an alternative vision of cosmic evolution. Jayant Narlikar’s work continues to inspire cosmologists seeking deeper insights into the structure and origin of the universe