A ghost particle and the quest to unravel a cosmic mystery

Even as the world is grappling with the greatest threat to internationalism since World War II, the world scientific community continues to work in collaboration and is on the threshold of some path-breaking discoveries in different fields of science.

- SATISH KUMAR SHARMA

One such field is cosmology which is poised to answer a fundamental question about the creation of universe - why matter exists?

The question has puzzled the scientists for decades because according to the Standard Model of Particle Physics (SM), for each particle of matter, a particle of anti-matter with opposite charge is created and on collision they annihilate each other in a burst of energy. But within one trillionth of a second of the Big Bang, something happened because of which, for every 3 billion particles of matter and antimatter that were created and annihilated, 1 excess particle of matter remained as surplus.

This surplus has gone into the formation of all the visible and invisible matter in the universe. The visible matter comprises - galaxies, stars, planets, satellites, their debris and all the swirling clouds of heavenly dust. The invisible matter is dark matter which cannot be seen but we know it exists because it has been observed to impact gravity.