This is the only sure way I know to counter the anti-Copernican idea that the universe is accelerating in our epoch - to get rid of the problem entir… - John Moffat

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.

Today, like the elusive planet Vulcan in the nineteenth century, dark matter is accepted by the majority of astronomers and physicists as actually existing. Dark matter, although it has never been seen, is part of the generally accepted standard model of physics and cosmology, which also includes the big bang beginning of the universe.

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.