- 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.
- Elvis Presley (Wikipedia)
Elvis Aaron Presley (January 8, 1935 – August 16, 1977), commonly referred to by his first name, Elvis, was an American singer and actor. Known as the “King of Rock and Roll”, he is regarded as one of the most significant cultural figures of the 20th century. Presley’s energized interpretations of songs and sexually provocative performance style, combined with a singularly potent mix of influences across color lines during a transformative era in race relations, brought both great success and initial controversy.
- Anthropic principle (Wikipedia)
The anthropic principle, also known as the “observation selection effect”, is the hypothesis, first proposed in 1957 by Robert Dicke, that the range of possible observations that we could make about the universe is limited by the fact that observations could only happen in a universe capable of developing intelligent life in the first place. Proponents of the anthropic principle argue that it explains why this universe has the age and the fundamental physical constants necessary to accommodate conscious life, since if either had been different, we would not have been around to make observations. Anthropic reasoning is often used to deal with the notion that the universe seems to be finely tuned for the existence of life.