He is an expert in geophysics.

He is an expert in theoretical physics.

He has a deep interest in archaeology.

He understands the importance of learning.

He is majoring in psychology.

Gaku is my best friend.

Strong interaction is one of the four fundamental forces in particle physics.

Fundamental interaction is one of the most important forces in physics.

Gravitational interaction creates attraction between objects.

Electromagnetic interaction is one of the fundamental forces used to explain the force between substances.