Irrational number number to ratios of continuous magnitude. In his commentary on Book 10 of the "Elements", the Persian mathematician Al-Mahani (d. 874/884) examined and classified quadratic irrationals and cubic irrationals. He provided definitions for rational and irrational magnitudes, which he treated as irrational numbers. He dealt with them freely but explains them in geometric terms as follows: In contrast to Euclid's concept of magnitudes as lines, Al-Mahani considered integers and fractions as rational magnitudes, and square roots and cube roots as irrational magnitudes. He also introduced an arithmetical approach to the concept of irrationality, as he attributes the following to irrational
Culture of fear that perceptions of risk, ideas about safety and controversies over health, the environment and technology have little to do with science or empirical evidence. Rather, they are shaped by cultural assumptions about human vulnerability. Furedi say that "we need a grown-up discussion about our post-September 11 world, based on a reasoned evaluation of all the available evidence rather than on irrational fears for the future. British academics Gabe Mythen and Sandra Walklate argue that following terrorist attacks in New York, the Pentagon, Madrid, and London, government agencies developed a discourse of "new terrorism" in a cultural climate of fear and