“The cyclic universe theory predicts no gravitational waves from the early universe.”
- January 8, 1942 – March 14, 2018
- British
- Theoretical physicist, science writer
- Announced the black hole singularity theorem and Hawking radiation, and contributed to the popularization of science with his book “Talking about the Universe”
Quote
“The cyclic universe theory predicts no gravitational waves from the early universe.”
Explanation
In this quote, Stephen Hawking touches on a specific prediction of the cyclic universe theory, which is a cosmological model suggesting that the universe undergoes an eternal series of cycles—expansion followed by contraction—repeating over vast periods of time. According to this theory, the universe doesn’t have a single beginning or end, but instead, it “resets” after each cycle. The statement that the theory predicts “no gravitational waves from the early universe” is significant because gravitational waves are ripples in space-time caused by violent cosmic events, such as the collision of black holes or the rapid acceleration of massive objects.
One of the major areas of research in modern cosmology is the study of the early universe, particularly during the period known as the cosmic inflationary epoch, which is believed to have occurred just after the Big Bang. In this model, inflation was a period of rapid expansion, during which tiny fluctuations in space-time could have generated gravitational waves that might be detectable today. However, the cyclic universe theory suggests that the nature of the early universe in each cycle would have been different from the Big Bang model, and these gravitational waves would not be a feature of the early universe’s history.
This point is relevant because gravitational waves could provide a direct observational signature of the conditions that existed in the early universe, allowing scientists to test different cosmological models. If the cyclic universe model is correct, it implies that the signature of earlier cycles would not include these gravitational waves. This presents a challenge for testing the theory against observations, as the absence of detectable gravitational waves from the early universe could make it harder to distinguish between the cyclic model and the more widely accepted Big Bang theory.
The quote highlights the theoretical debates and challenges in cosmology, where different models of the universe’s origin and evolution can make competing predictions about the observable features of the cosmos. Hawking’s expertise in the field made him one of the foremost voices contributing to these discussions, and his work has influenced how scientists approach the search for evidence supporting one model over another.
