Theory of relativity, quantum physics key to explaining Big Bang, says scientist

Astrophysicist P. Ajith discusses universe expansion, combining Einstein's theory of relativity and quantum physics for clarity.

A combination of Albert Einstein’s theory of relativity and quantum physics may help explain the expansion of the universe from a singular entity, P. Ajith, astrophysicist with the International Centre for Theoretical Sciences, Bengaluru, has said.

He was at the Regional Science Centre and Planetarium (RSCP) in Kozhikode on Thursday (January 2) to deliver a lecture demonstration on ‘Universe: yesterday, today and tomorrow’. It is the first in the ‘Cosmic Snapshots’ series of lectures being organised by the RSCP.

Mr. Ajith pointed out that the concept of a primordial atom, proposed in the early 20th century by Georges Lemaitre, who is considered the father of the Big Bang theory, was just a “story” and not a scientific fact. According to Lemaitre, the universe began with an explosion from a single particle at a specific moment in time. “The primordial atom is just a way of explaining what might have happened. At some point, the universe shrank into one tiny entity. To understand what happened then, we need to combine Einstein’s theory of relativity with quantum physics,” he said.

Mr. Ajith traced the history of our understanding of the universe, starting with Nicolaus Copernicus, who first suggested a sun-centered universe, and Galileo Galilei, who proved it through observations. “Galileo’s discoveries changed how we saw the universe and sparked the age of enlightenment and the Renaissance, leading to modern science and technology,” he said. German astronomer Kepler improved Copernicus’ ideas, discovering that planets move in elliptical orbits. Isaac Newton later proposed that the same force making an apple fall also keeps planets revolving around the Sun.

Mr. Ajith highlighted that Newton’s laws of motion are still used today, especially in rocket science. He explained how the sun-centered universe concept evolved, revealing the Sun as just a small part of the Milky Way. Later, astronomers debated whether Earth was part of a single galaxy or many. Edward Hubble then developed a telescope to measure the distance to distant galaxies. Mr. Ajith also mentioned Einstein’s theory, which described gravity not as a force, but as the effect of space-time, a concept he introduced to explain how gravity impacts space and the flow of time.