of Soviet physicist Yakov Borisovich Zel'dovich on structure formation from primordial density perturbations in the cosmic plasma has led to the general use of the term Harrison-Zel'dovich spectrum for primordial random fluctuations characterised by a scale-invariant power spectrum. Harrison was fascinated with Olbers's paradox (the night sky is dark despite the vast number of stars in the universe). In 1964, he published detailed calculations that solved the paradox by concluding that stars do not generate enough energy to illuminate the entire sky. In 1987, he published a book, Darkness at Night, mulling over the Paradox and its rich history. This book clarified that the lack of energy is not primarily because the universe is expanding, but rather because the stars and galaxies have had only about 15 billion years to radiate, and do not have sufficient energy to keep radiating for much longer. Darkness at Night lays out how Harrison discovered that Edgar Allan Poe's essay Eureka anticipated this conclusion, and that Lord Kelvin had reached a very similar conclusion in a 1901 article ignored for 80 years until Harrison drew attention to it. Harrison's text Cosmology: The Science of the Universe describes the problem of the cosmic edge of the universe by quoting 5th century BC soldier-philosopher Archytas, who questioned what occurs as a spear is hurled across the outer boundary of the universe. His final book, Masks of the Universe (2nd ed., 2003), questions current perceptions of reality, asking whether present cosmology, with ordinary matter, dark matter, plus dark energy, is yet only another "mask" obscuring a Universe which will remain perforce forever unknown to humans. Books by Harrison 2003 (1985). Masks of the Universe. Cambridge Univ. Press. 2000 (1981). Cosmology: The Science of the Universe. Cambridge Univ. Press. . 1987. Darkness at Night: A Riddle of the Universe, Harvard University Press. . 1965. Elementary cosmology. See also Olbers's paradox Notes References Edmund Blair Bolles, 1999. Galileo's Commandment: 2,500 Years of Great Science Writing. Irvine, W. M., "Physics Today Obituaries: Edward R. (Ted) Harrison," PhysicsToday.org, 2007-02-23. External links 20th-century British astronomers 1919 births 2007 deaths Alumni of the University of London University of Arizona faculty University of Massachusetts Amherst faculty British physical chemists British Army personnel of World War II Fellows of the Institute of Physics Fellows of the American Physical Society People associated with CERN