- In the past few years the search for a consistent quantum theory of gravity and the quest for a unification of gravity with other forces have led to a great deal of interest in theories with extra spatial dimensions. These extra spatial dimensions are unseen because they are compact and small, presumably with typical dimensions of the Planck length, Pl = 1.616 × 10-33 cm. If the “internal” dimensions are static and small compared to the large “external” dimensions the only role they would play in the dynamics of the expansion of the Universe is in determining the structure of the physical laws. However, if the big bang is extrapolated back to the Planck time, then the characteristic size of both internal and external dimensions were the same, and the internal dimensions may have had a more direct role in the dynamics of the evolution of the Universe.
- We live in a hot, expanding Universe. We also live in a Universe that on 'large' scales is homogeneous, the same at every point, and isotropic, the same in every direction. There is an ample (and growing) body of evidence for homogeneity and isotropy. The isotropy and homogeneity of the Universe is the most fundamental principle in modern cosmology. In fact, it is called the Cosmological Principle.
- (1994). "Particle physics and cosmology". arXiv preprint astro-ph/9403007. (quote from p. 6)
- The precision cosmological measurements have lead to the latest cosmological model, usually called the standard cosmological model, or ΛCDM, where Λ indicates Einstein’s cosmological constant (or more generally, dark energy), and CDM stands for cold dark matter. ... The most remarkable feature of the standard cosmological model is that it seems capable of accounting for all cosmological observations; i.e., it seems to work!
- (2007). "Cosmology and the Unexpected". arXiv preprint astro-ph/0709.3102. (quote from p. 1)
- Leon and I used to tease each other, because he's an experimentalist and I'm a theorist. And experimentalists are jealous of theorists, because theorists are smarter.
- (October 21, 2019)"Trailblazer of Physics: The Extraordinary Life of Leon Lederman Program". C2ST TV, YouTube. (quote at 28:51 of 1:20:44)