Halton Arp (1927–2013) was an American astronomer and the author of 1987 book Quasars, redshifts and controversies, who for the reason of not believing in the Big Bang hypothesis was taken away the telescope time from, and in this way forced to emigrate from the U.S. He later lived in Germany, continuing his research of quasars that he considered local to their galaxies rather than remote objects at cosmological distances. In 1993 Arp co-authored with J. Narlikar a paper on the geometry of spacetime that proposed the idea of flat spacetime (also proposed by others). Arp's research contradicted the idea of an expanding universe and confirmed the idea that the universe is stationary as it was shown with relativistic physics and Newtonian math in 1985, when it was discovered that the Hubble constant of stationary universe is
where is speed of light in vacuum, is radius of curvature of space (called "Einstein's radius"), is Newtonian gravitational constant, and is density of space  and so the cosmological redshift is exactly Arp's Intrinsic redshift with which one may measure the average density of universe (and possibly also the density of space around quasars).
- John G. Hartnett (31 December 2013). Big-bang-defying giant of astronomy passes away. creation.com. Retrieved on 14 January 2014. “Halton Arp passed away on Saturday morning 28th December 2013 in Munich, Germany.”
- Arp, Halton, 1987, "Quasars, redshifts and controversies", Interstallar Media, 2153 Russel Street, Berkeley, CA, ISBN 0-941325-00-8.
- Narlikar, J. & Arp, H., 1993, "Flat spacetime cosmology - a unified framework for extragalactic redshifts", Astrophysical Journal, Part 1 (ISSN 0004-637X) vol. 405, no. 1, The American Astronomical Society, p.51-56, Bibliographic code: 1993 ApJ...405...51N
- See a detailed explanation of the mechanism of Einsteinian gravitation Gravitation demystified. It explains the Einsteinian gravitational force as inertial push at the quantum level in flat spacetime.
- See Essay:Hubble redshift in Einstein's universe. Except for Conservapedia (before access to the paper were blocked by the University of Warsaw, Poland), it was never published by any mainstream scientific journal and therefore remains unknown to the physicists and astronomers