Speed of light the fundamental excitations (or quanta) of the electromagnetic field, called photons. In QED, photons are massless particles and thus, according to special relativity, they travel at the speed of light in vacuum. Extensions of QED in which the photon has a mass have been considered. In such a theory, its speed would depend on its frequency, and the invariant speed "c" of special relativity would then be the upper limit of the speed of light in vacuum. No variation of the speed of light with frequency has been observed in rigorous testing, putting stringent limits on the mass of the
In the Light of What We Know when the true pleasure of a work of fiction is its gravitational pull upon us?” In a 4,000-word review for "The New Yorker", the critic James Wood described Rahman as “a deep and subtle storyteller,” and praised the novel as “astonishingly achieved…Isn’t this kind of thinking—worldly and personal, abstract and concrete, essayistic and dramatic—exactly what the novel is for? How it justifies itself as a form?…"In the Light of What We Know" is what Salman Rushdie once called an ‘everything novel.’ It is wide-armed, hospitable, disputatious, worldly, cerebral. Ideas and provocations abound on every page.” Australian literary critic Louise Adler