- On the dimensionality of spacetime (space.mit.edu)
Some superstring theories have more than one effective low-energy limit corresponding to classical spacetimes with different dimensionalities. We argue that all but the (3 + 1)-dimensional one might correspond to ‘dead worlds’, devoid of observers, in which case all such ensemble theories would actually predict that we should find ourselves inhabiting a (3 + 1)-dimensional spacetime. With more or less than one time dimension, the partial differential equations of nature would lack the hyperbolicity property that enables observers to make predictions. In a space with more than three dimensions, there can be no traditional atoms and perhaps no stable structures. A space with less than three dimensions allows no gravitational force and may be too simple and barren to contain observers.
- Ayn Rand (Wikipedia)
Alice O’Connor (born Alisa Zinovyevna Rosenbaum; February 2 [O.S. January 20], 1905 – March 6, 1982), better known by her pen name Ayn Rand (/aɪn/), was a Russian-born American writer and philosopher. She is known for her fiction and for developing a philosophical system she named Objectivism. Born and educated in Russia, she moved to the United States in 1926. After two early novels that were initially unsuccessful and two Broadway plays, she achieved fame with her 1943 novel, The Fountainhead. In 1957, Rand published her best-known work, the novel Atlas Shrugged. Afterward, until her death in 1982, she turned to non-fiction to promote her philosophy, publishing her own periodicals and releasing several collections of essays.