<Tr> <Td> ∇ (\ displaystyle \ nabla) </Td> <Td> nabla </Td> <Td> delta (differential operator) </Td> <Td> </Td> </Tr> <Tr> <Td> Δ (\ displaystyle \ Delta) </Td> <Td> Delta </Td> <Td> the Laplace operator </Td> <Td> per square meter (m) </Td> </Tr> <Tr> <Td> ∂ (\ displaystyle \ partial) </Td> <Td> "der", "dow", "die", "partial" or simply "d" </Td> <Td> partial derivative (e.g. ∂ y / ∂ x (\ displaystyle \ partial y / \ partial x)) </Td> <Td> </Td> </Tr> <Tr> <Td> ◻ (\ displaystyle \ Box) </Td> <Td> D'Alembert operator </Td> <Td> ∇ 2 − ∂ t 2 (\ displaystyle \ nabla ^ (2) - \ partial _ (t) ^ (2)) </Td> <Td> </Td> </Tr>

What does the symbol q mean in physics