This phenomenon remains unexplained for scientists.

Demography is an important tool for understanding various aspects of society.

He is a professor of physics.

Satoru is my best friend.

My mother woke me up.

He is an expert in nuclear physics.

He is an expert in nuclear physics and has won many awards in the field.

He is an expert in astrophysics, and his research is highly valued around the world.

He is an expert in astrophysics.

He is an expert in applied physics.