Edward Robert Harrison - Work

Work

Ted Harrison had broad interests, and he published more than 200 papers, primarily in astrophysics and cosmology, but also in space sciences, high energy physics, plasma physics and physical chemistry. He was an elegant writer with a passion for the history of ideas. His books (cf. especially his text Cosmology) illustrated points of physics or cosmology with many literary, philosophical, and historical references.

The work of Harrison and 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 Olber'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 BCE 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.