physics
a cryogenists
a balance
A mechanical engineer.
A scientist would probably be a physicist or a chemist, but engineers can also study energy, and designing heat engines would be an engineers job. A specialist in this field would be a thermodynamicist.
a physicist
physics
physics
physics
A microbiologist.
hyponism :)
A paleontologist would generally study paleontology.
An astronomer.
Volcanologist.
a physist
historians
A Botanist