This professor has a nice theory (hydrogen will never work in air planes), which is trivially falsified by simply pointing at planes that fly that use hydrogen

This professor has a nice theory (hydrogen will never work in air planes), which is trivially falsified by simply pointing at planes that fly that use hydrogen as a fuel. That seems to have already happened. There are multiple companies that have flying prototypes. Hydrogen planes are now an engineering and logistics challenge. The science is ancient history.