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Conformal cyclic cosmology

Explore conformal cyclic cosmology, a theory proposing a cyclic universe structure, its implications, and potential evidence.

Conformal Cyclic Cosmology: A New Perspective on the Universe


In recent years, the theory of conformal cyclic cosmology (CCC) has gained significant attention within the scientific community. This innovative concept, originally proposed by renowned mathematician and theoretical physicist Sir Roger Penrose, seeks to expand our understanding of the universe’s origin, evolution, and ultimate fate. By merging ideas from general relativity and cosmology, Penrose suggests that our universe is just one of an infinite series of cosmic epochs, each arising from the remnants of its predecessor.

Background and Motivation

Since the early 20th century, the Big Bang Theory has been the prevailing explanation for the origin of the universe. According to this theory, the universe began as an infinitely dense and hot singularity, expanding rapidly and cooling over time to form the structure we observe today. However, the Big Bang Theory faces several challenges, such as the nature of dark matter and dark energy, the fine-tuning of cosmic parameters, and the absence of a well-defined initial state.

Conformal cyclic cosmology aims to address these challenges by proposing a cyclic model of the universe, where each cycle, or “aeon,” is connected to the next through a continuous process of expansion and contraction. This model eliminates the need for an initial singularity and provides an alternative explanation for the observed homogeneity and isotropy of the universe.

The Concept of Conformal Invariance

Central to the CCC model is the idea of conformal invariance, a property of spacetime that remains unchanged under a transformation that scales distances but preserves angles. In simpler terms, this means that geometric shapes can be stretched or compressed without altering their fundamental properties. Penrose leverages this concept to explain the transition between successive aeons in the CCC model.

According to general relativity, the universe’s expansion should slow down due to the attractive force of gravity. However, observations of distant supernovae indicate that the universe’s expansion is accelerating, which has been attributed to the mysterious dark energy. In the CCC model, Penrose suggests that this accelerating expansion is, in fact, an illusion caused by a conformal rescaling of spacetime, implying that the universe’s distant past and far future are more closely related than previously believed.

The Cyclic Nature of the Universe

In the conformal cyclic cosmology model, each aeon begins with a “Big Bang” event, followed by an expansion phase where matter and radiation dilute and cool. Eventually, the universe enters a dark energy-dominated phase, where galaxies drift apart, and the cosmic microwave background (CMB) fades. As the aeon approaches its end, the conformal rescaling occurs, resulting in a smooth, empty, and cold universe that becomes the starting point for the next aeon.

Crucially, this cyclic process implies that the universe has no beginning or end, and the observed large-scale structure is a natural consequence of this continuous cosmic evolution.

Evidence for Conformal Cyclic Cosmology

One of the most intriguing aspects of the CCC model is the potential for observational evidence. Penrose has suggested that the cosmic microwave background (CMB) radiation, the relic radiation from the early universe, might contain traces of previous aeons in the form of circular patterns known as “Hawking points.” These points, named after the late physicist Stephen Hawking, represent areas where black holes from previous aeons have evaporated, leaving behind an imprint on the CMB radiation.

While some studies claim to have identified possible Hawking points in the CMB data, the scientific community remains divided on the validity of these findings. Critics argue that the observed patterns could be due to chance or instrumental artifacts, and further research is necessary to confirm or refute the existence of Hawking points as evidence for CCC.

Implications and Future Directions

If proven accurate, the conformal cyclic cosmology model would have profound implications for our understanding of the universe. By proposing a cyclical structure instead of a singular origin, the CCC model offers a new perspective on the nature of time, the evolution of cosmic structure, and the fate of the universe. It also poses intriguing questions about the role of entropy, information, and causality across aeons.

Future research in this area will likely focus on refining the CCC model and searching for more robust observational evidence. The upcoming James Webb Space Telescope, set to launch soon, could provide valuable data for testing the CCC model’s predictions. Additionally, advancements in theoretical physics, such as the development of a quantum theory of gravity, may help reconcile the CCC model with other cosmological theories.


Conformal cyclic cosmology is an innovative and thought-provoking approach to understanding the cosmos, challenging conventional wisdom and offering new insights into the origin, evolution, and ultimate fate of the universe. While the theory remains controversial and requires further validation, it highlights the importance of continually questioning and expanding our understanding of the cosmos. As the search for evidence continues, the CCC model serves as a powerful reminder that the universe’s mysteries are far from being fully unraveled.