Radial velocity Radial velocity The radial velocity of an object with respect to a given point is the rate of change of the distance between the object and the point. That is, the radial velocity is the component of the object's velocity that points in the direction of the radius connecting the object and the point. In astronomy, the point is usually taken to be the observer on Earth, so the radial velocity then denotes the speed with which the object moves away from or approaches the Earth. In astronomy, radial velocity is often measured to the first order of approximation by
What Is it Like to Be a Bat? What Is it Like to Be a Bat? "What is it like to be a bat?" is a paper by American philosopher Thomas Nagel, first published in "The Philosophical Review" in October 1974, and later in Nagel's "Mortal Questions" (1979). In it, Nagel argues that materialist theories of mind omit the essential component of consciousness, namely that there is something that it is (or feels) like to be a particular, conscious thing. He argues that an organism has conscious mental states, "if and only if there is something that it is like to be that organism—something it is like "for"