Abstract :
Scientists are accustomed to thinking of freedom of information as a firm tradition ¿ the truths of physical knowledge are universal and if you don´t disclose freely and rapidly a new truth you have discovered, someone may beat you to it. But even in pure science, and to a much greater extent in applied science and technology, constraints on release of technical information do exist, and always have existed. Sometimes they have been commercial, sometimes political, sometimes they protect the national security and sometimes they protect a person or institution from embarrassment.
