Scientists are not free to express their opinions

 Quote from James Lovelock (The Ages of Gaia)

"One might think that the academic scientist is the analogue of the independent artist. In fact, almost all scientists are employed by some large organizations, government departments, universities or a multinational company. Only rarely they are free to express their personal point of view. 

They may think they are free, but they are almost all employees who have changed freedom of thought for good working conditions, a regular income, a job and a pension. They are also limited by an army of bureaucratic forces from funding agencies to health and safety organizations. Scientists are also limited by tribal rules of the discipline they belong 

A physicist would have difficulties in do research in chemistry and a biologist would find it almost impossible to enter in physics subjects. To complete the above, in recent years the "purity" of science is closely guarded by a self-imposed inquisition called the peer "review"."
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