If galaxies are receding from each other, why are the Milky Way and Andromeda on a collision course? What was there before the Universe was born? Is there a limit to the expansion of the Universe?
You wouldn't expect a priest to answer such questions, but with Fr (Dr) Richard (Richie) D'Souza, SJ, anything of this kind is possible.
The 43-year-old Goan Jesuit, who is part of the prestigious Vatican Observatory, spent a couple of hours on two days in the past week explaining astronomy to a mixed and interested audience from Goa and beyond.
Some came in from as far away as the US to hear the young astronomer talk.
Dr D'Souza, a Jesuit who studied at St Britto High School and St Xavier's college (both in Mapusa), and a slew of prestigious institutions in Mumbai, Europe and the US, has been credited with leading the team which made a path-breaking discovery about a long-lost galaxy called M32p, which is considered a sibling of our galaxy the Milky Way.
He spoke at an online conference in Goa, which drew a 170-strong audience. It was organised by the Collaborative Learning Cafe, a new network by friends of the Jesuits in Goa to promote job training, life-long learning and hobby courses.
In his two-part talk, Dr D'Souza focussed on the size and origin of the Universe, the origin of the elements that make up life on earth, the end of the universe, and possibilities of discovering "extra-terrestrial planets and the search for signatures of life".
He offered his responses to queries raised by the audience and they were generally appreciative of his clear and succinct explanations.
George Lemaitre -- the twentieth-century Belgian Catholic priest, mathematician-astronomer, and physics prof -- was the first to propose the idea of the Big Bang, he noted.
Asked about the time frame involved he said, "We believe that the Universe initiated in a point ~13.7 billion years ago. We come to this number based on the fact that we can observe the Universe expanding, and we can extrapolate backwards in time to get the age of the Universe."
Dr D'Souza said the names given to things have changed over time.
“A hundred years ago, a galaxy and the Universe was the same thing. In fact, when people realised that the Andromeda galaxy was far away, they called it 'another Universe'. Today, we talk about a single Universe and multiple galaxies," he said.
There is a theory that postulates that they may be "multiple Universes", which cannot communicate with each other.
Other issues that came up were on how Pluto had been perceived in recent times, the "death" of a galaxy, the Andromeda-Milky Way collision-course and other subjects.
Some teachers at his former institutions, priests from Goa, and those who knew his family were among those present.