"The eighteenth-century German philosopher Immanuel Kant had conjectured that Messier's nebulae were distant "island universes" outside our Milky Way galaxy, but many scientists in the early twentieth century disagreed."

“Hunting for elusive dark matter is now a multibillion dollar international scientific industry.”

“When I was a student at Trinity College, Cambridge, in the 1950s, Sir Isaac Newton's presence was still almost palpable.”

“Giving up Einstein's theory of gravity is simply unacceptable to many in the community. It may take a new generation of physicists to view the evidence with unclouded eyes.”

“It is hard to understand how this infinitely dense singularity can evaporate into nothing. For matter inside the black hole leak out into the universe requires that it travel faster than the speed of light.”

“In estimating the amount of dark matter, cosmologists developing the standard model have to make some rather strong assumptions about their observations.”

“One truth we have been able to count on concerning scientific persuit over the centuries has been that only testable theories survive the intense scrutiny of experimental science.”