His specialty is physics.

My house is near the mountains.

He is researching about a new energy source.

He is conducting research on a new energy source.

He is known as a person with learning.

Tidal force is the force that causes the tides of the Earth's oceans.

He is majoring in tidal science.

My major is oceanography.

Marine pollution is a global issue, and all countries should cooperate to find a solution.

He couldn't say anything about issues outside of his field of expertise.