Color it is viewed, may alter its perception considerably; for example, a low-intensity orange-yellow is brown, and a low-intensity yellow-green is olive green. The color of an object depends on both the physics of the object in its environment and the characteristics of the perceiving eye and brain. Physically, objects can be said to have the color of the light leaving their surfaces, which normally depends on the spectrum of the incident illumination and the reflectance properties of the surface, as well as potentially on the angles of illumination and viewing. Some objects not only reflect light, but also transmit light
Moving walkway the book, the fast lane stops while the second lane keeps running at ). In the Wells and Asimov works there are more steps in the speed scale and the speeds are less extreme. In Arthur C. Clarke's novel, "Against the Fall of Night" (later rewritten as "The City and the Stars") the Megacity of Diaspar is interwoven with "moving ways" which, unlike Heinlein's conveyor belts, are solid floors that can mysteriously move as a fluid. In the novel, Clarke writes, In his non-fiction book "Profiles of the Future", Arthur C. Clarke mentions moving sidewalks but made of some sort