Redshift

Scientific Theory
Name	Redshift
Type	Astronomical observation and its disputed interpretation
Author(s)	Interpretation disputed — see Halton C Arp, Ari Brynjolfsson, Paul Marmet, John W Kierein, Lyndon E Ashmore and others
Keywords	redshift, Hubble's law, expanding universe, tired light, plasma redshift, intrinsic redshift, Big Bang
Year	1929 onward

Redshift is the observed shift of spectral lines from distant astronomical objects toward longer (redder) wavelengths, conventionally denoted z. It is the single most consequential measurement in modern cosmology: the entire extragalactic distance scale, the expansion of the universe, and the Big Bang itself all rest on one particular interpretation of what redshift means.

That interpretation — that redshift is essentially a velocity effect, so that a larger redshift means a greater distance and a faster recession — is precisely what the critical tradition documented on this wiki disputes. The observation itself is not in question; the inference from it is. A substantial body of work catalogued here argues that redshift can be produced by several physical processes that have nothing to do with recession, that some redshift is intrinsic to the object, and that in consequence redshift is not a reliable measure of distance — which would remove the observational foundation of the expanding-universe model.

The observation

When light from a distant source is dispersed into a spectrum, the characteristic absorption and emission lines of known elements appear at longer wavelengths than they do in the laboratory. The fractional shift, z = Δλ⁄λ, is straightforward to measure and is not itself controversial. Everything that follows depends on what is held to cause it.

The standard interpretation

Conventional cosmology attributes redshift to three effects: the cosmological redshift produced by the expansion of space, the Doppler shift from an object's own motion, and a normally small gravitational redshift. Since the first is taken to dominate at large distances, redshift is converted directly into distance through Hubble's law, and the observed relation between redshift and distance is read as evidence that the universe is expanding from an initial hot, dense state.

Why the interpretation is disputed

Discordant associations

The most direct observational challenge comes from objects of very different redshift that appear to be physically connected. Halton C Arp compiled many such cases — quasars apparently joined by luminous bridges to low-redshift galaxies, and high-redshift quasars found in improbable proximity to nearby active galaxies. If even one such association is real, redshift cannot be a pure distance indicator. See Intrinsic redshift and Quasar.

Quantization

Redshifts also appear not to be smoothly distributed. William Tifft reported that galaxy redshifts cluster at preferred values, and K. G. Karlsson found a periodicity in quasar redshifts. A genuine spread of recession velocities should be continuous, so proponents read these regularities as evidence of a non-velocity component. See Redshift quantization.

Alternative mechanisms

Much of the research catalogued on this wiki is devoted to physical mechanisms that can redden light without invoking recession. The principal families are:

• Tired light and New Tired Light — the proposal, originating with Fritz Zwicky, that photons lose energy progressively over cosmological path lengths. Lyndon E Ashmore has developed a modern quantitative version, "New Tired Light," in which photons interact with electrons in the intergalactic medium; see New Tired Light Correctly Predicts the Redshift of the CorBor Galaxy Cluster and Tired Light.
• Plasma redshift — Ari Brynjolfsson's account, in which photons lose energy to hot, sparse plasma, reproducing the magnitude–redshift relation of supernovae without expansion or dark energy; see Plasma Redshift Cosmology and Magnitude-Redshift Relation for SNe Ia, Time Dilation, and Plasma Redshift.
• Compton-effect redshift — John W Kierein's proposal that redshift arises from Compton scattering of light on its passage through space; see Gravitation as a Compton Effect Redshift of Long Wavelength Background Radiation.
• Inertial induction — Amitabha Ghosh's velocity-dependent inertial induction, a gravitational drag on photons acting as a tired-light mechanism; see Velocity-Dependent Inertial Induction: A Possible Tired-Light Mechanism.
• Variable mass — the Hoyle–Narlikar framework adopted by Arp, in which newly created matter has low particle mass and therefore intrinsically redshifted spectra, the redshift decaying as the matter ages.
• Gravitational and field mechanisms — a range of proposals treating cosmic redshift as gravitational in origin or as arising from a varying light speed; see Gravitational Redshift within a Non-Expanding Universe and Gravitational Cosmic Redshift with Variable Light Speed.
• Other proposals catalogued here include variable electrical charge (Variable Electrical Charge Cosmological Redshift), zero-point energy (Zero Point Energy and the Redshift), and laboratory approaches such as Generating a Redshift in the Lab.

Implications for cosmology

If redshift is not primarily a recession effect, the expansion of the universe is not established by the redshift–distance relation, and a non-expanding or infinite universe becomes viable. Much of the work here follows that path — see An Infinite Non-Expanding Universe in Dynamic Equilibrium, Nature of the Non-Expanding Universe, and A New Mechanism to Explain Observations Incompatible with the Big Bang by Paul Marmet. On this view the phenomena usually taken as confirming the Big Bang — the Hubble relation, supernova dimming, the microwave background — call for re-examination rather than being treated as settled.

Mainstream objections

Standard cosmology holds that tired-light and scattering mechanisms would blur distant images and disturb the black-body spectrum of the microwave background in ways not observed, and that the time dilation seen in distant supernova light-curves is a direct signature of expansion. Proponents of the alternatives reply that their specific mechanisms are constructed to avoid blurring, and that the supernova and surface-brightness data are themselves fitted successfully without expansion — the argument advanced in Surface Brightness in Plasma-Redshift Cosmology.

On this wiki

Redshift is among the most heavily represented subjects here. Contributors with pages include Halton C Arp, Ari Brynjolfsson, Paul Marmet, John W Kierein, Lyndon E Ashmore, Amitabha Ghosh, Martin Kokus and Eugene I Shtyrkov. Further material is indexed under Category:Cosmology.

See also

• Intrinsic redshift
• Redshift quantization
• Quasar
• Tired Light
• Big Bang
• Halton C Arp
• Category: Cosmology