Newton's laws of motion Newton's laws of motion for rigid bodies called Euler's laws of motion, later applied as well for deformable bodies assumed as a continuum. If a body is represented as an assemblage of discrete particles, each governed by Newton's laws of motion, then Euler's laws can be derived from Newton's laws. Euler's laws can, however, be taken as axioms describing the laws of motion for extended bodies, independently of any particle structure. Newton's laws hold only with respect to a certain set of frames of reference called Newtonian or inertial reference frames. Some authors interpret the first law as defining what
Three Roads to Quantum Gravity Three Roads to Quantum Gravity Three Roads to Quantum Gravity: A New Understanding of Space, Time and the Universe is the second non-fiction book by American theoretical physicist Lee Smolin. The book was initially published on May 30, 2001 by Basic Books as a part of "Science Masters" series. Smolin discusses three potential approaches by which a unified theory of quantum gravity, arguably the foremost issue in theoretical physics, may be realized. Approaches discussed include string theory, M-theory, and Smolin's preferred approach, loop quantum gravity. Smolin suggests that these approaches may be approximations of a single, underlying theory. —"The Guardian"