In 1924 Edwin Hubble demonstrated that the small hazy patches of 
light we see in the sky are "enormous islands of billions of stars." 
Examination with large telescopes revealed that the fainter and 
smaller a galaxy appeared, the higher, in general, was its redshift. 

`Redshift' describes the characteristic lines in the spectrum due to 
hydrogen, calcium and other elements which appear at longer (redder) 
wavelengths than in a terrestrial laboratory. The simple explanation 
attributes this effect to the recession velocity of the emitting 
source ^ like the falling pitch of a receding train whistle, the 
Doppler effect. It was therefore concluded that the fainter and 
smaller the galaxy, the more distant it is, and the faster it is 
moving away from us. This velocity interpretation of the redshift ^ 
the apparent brightness relation ^ forms the standard interpretation 
of the Hubble Law. 

Einstein wrote equations at about this time that attempted to 
describe the behaviour of the entire universe, the totality of 
existence. His equations pointed to its probable instability. 
Gravitation was either strong enough to be in the process of 
contracting the universe, or too weak to prevent its expansion. 
Extrapolating these velocities back to the origin of time gave rise 
to the concept of the universe being created in a primeval 
explosion ^ the Big Bang cosmology. 

According to Halton Arp, observations began to accumulate from 1966 
that could not be accounted for by this conventional explanation of 
the redshift effect. Some extra-galactic objects had to have 
redshifts which were not caused by a recesson velocity. 

At the very least, it seemed that some modification had to be made 
to the theory, but some influential specialists reacted very 
strongly to these anomalous observations. It was said they "violated 
the known laws of physics" and must therefore be wrong; that is to 
say, a useful hypothesis had been enshrined in dogma. Arp states 
that the dogmatists attitude was akin to saying `At this moment in 
history we know all the important aspects of nature we shall ever 
know.' 

The first challenge to the conventional theory came with the advent 
of radio astronomy and the discovery of quasars (quasi-stellar 
objects). It was no longer possible to view galaxies just as 
relatively quiescent aggregates of stars, gas and dust, all swirling 
in ordered rotation. Some are ripped asunder by huge explosions 
while others have nuclei that vary strongly in brightness and 
intermittently eject quantities of matter into space. The first 
quasar was discovered by Allan Sandage and Thomas Matthews, an 
optical and a radio astronomer working in collaboration, in 1963. 
Then, to great surprise, Martin Schmidt found that the initially 
puzzling lines were those of familiar elements but shifted far to 
the right. Why, when the highest redshifted galaxies had a maximum 
redshift of 20 to 40 percent of the velocity of light, did these 
stellar-looking objects suddenly appear with redshifts of 80 to 90 
percent? It was conjectured that some other mechanism was 
responsible. For example, redshifting could be caused by a very 
strong gravitational field. However, such explanations were quickly 
discarded; it was decided that quasars were the most luminous 
objects in the universe and that they were seen at such great 
distances that the expansion of the universe was giving them the 
largest possible recession velocity. 

Difficulties in this explanation were encountered almost 
immediately. Firstly, how could an object be so luminous? So much 
energy had never been encountered in previously observed galaxies. 
In some quasars the calculated density of charged particles was so 
high that there would be a problem of actually getting the photons, 
by which we see them, out of their interior. Very accurate 
positional measurements by radio telescopes (using very long 
baseline interferometry) revealed the astounding fact that some 
quasars appeared to be expanding at up to ten times the speed of 
light. This was in complete violation of the accepted laws of 
Einsteinian physics, in particular, that the speed of light is a 
physical constant that cannot be exceeded. Rather than regard these 
quasars as being at lesser distances so as to give them quite modest 
expansion velocities, conventional theorists attempted to 
incorporate the redshift effect into their existing beliefs. They 
attempted to explain these anomalies as an illusion caused by very 
exceptional conditions, such as ejection of matter towards the 
observer at nearly the speed of light. They ignored the direct 
evidence that these quasars were interacting with galaxies which 
were at a known and much nearer distance to us. 

As observations of quasars accummulated it became apparent that 
anomalies existed between their brightness and their distribution. 
One would expect quasars to be evenly distributed in the universe, 
but a disproportionate number appeared to be near its observable 
limit. These quasars are also brighter than expected. This gave rise 
to another bizarre explanation: it was suggested that as we looked 
out in space, and therefore back in time, we encountered a higher 
and higher density of quasars until suddenly, at a certain point, 
they ceased to exist! 

The orthodox view is that quasars are just abnormal (e.g. 
superluminous) galaxies and that they can only have a redshift 
caused by velocity. Arp drew attention to quasars interlinking with 
galaxies. But a large body of opinion now holds that galaxies can 
violate the redshift distance-relation. It is the most peculiar 
galaxies, those most like quasars, which offer the most compelling 
evidence for non-velocity redshift. 

This has two consequences, first it enormously strengthens the case 
that the redshift-distance law can be broken. It only requires one 
demonstrably inconsistent quasar or galaxy to establish that an 
additional cause of redshift ^ other than recession velocity ^ must 
be in operation. Because of the connection of quasars with galaxies, 
there are now several cases of observations that another origin of 
redshift exists. 

Secondly, it means that the mechanism for causing this non-velocity 
shift must be capable of operating on an entire conglomeration of 
stars, gas and dust. This is much more difficult than finding a 
mechanism which operates on the more compact and mysterious quasars. 

Interpretations
Arp gives many examples of non-velocity redshift. He then attempts 
to integrate his observations into the body of existing scientific 
knowledge, following the Brownian principle of induction of general 
laws as far as possible. If a scientist only reasons deductively 
from known laws he will never discover anything new, argues Arp. He 
suggests that not knowing a thing is wrong may be more important 
than knowing a hundred things are right. 

Central to Arp's disagreement with accepted theory is the fact that 
redshifts of extragalactic objects are not caused by velocity alone. 
There are numerous examples of this in quasars with redshifts 
approaching the velocity of light, of peculiar galaxies with 
redshifts from 1,000 to 30,000 km/sec and in more normal, companion 
galaxies in the range of a few hundred km/sec. 

The evidence clearly indicates that quasars have been ejected from 
active galaxy nuclei along with radio waves and x-rays. In view of 
the popularity of the notion of gravitational lensing Arp suggests 
instead that some gravitationally compact bodies are being ejected 
and that these ejected bodies are simply gravitationally amplifying 
objects in the far background which have a redshift caused by a 
recession velocity. This idea seems attractive, but does not explain 
galaxies with inconsistent redshifts. These galaxies seem to be 
interacting with much lower redshift galaxies so they must both be 
at the same distance from us. 

Arp postulates that the strong gravitional fields of large masses 
within individual quasars and discrepant galaxies account for large 
redshifts, but points out that even for typical quasars like ZC48, 
nebulosity around the nucleus is measured at about the same redshift 
as the nucleus. There is no redshift gradient and no apparent 
internal gravitational field. 

There have been many variations of `tired light' theories put 
forward. The basic idea is that light from extragalactic objects 
travels a long way through space before reaching us. In that 
journey, if anything interacts with the photon or if its energy 
decays with the passage of time, it will arrive with a smaller 
energy than it started with, i.e. it will be redshifted. The main 
difficulty with this model is that to rob a photon of some of its 
energy it must be jostled or perturbed, at least slightly. This 
means that its flight path is slightly deviated and the image of the 
emitting object becomes fuzzy. However, there is no evidence for 
this and high redshift objects appear as clear and sharp as low 
redshift objects. 

Whether gravitational fields result in collisions or perturbations 
which detract energy from photons or not, Arp postulates a "screen" 
between us and the object which removes, in discrete amounts, energy 
from the photons coming towards us. This leads to a model of shells 
of matter around redshifted objects, but he considers this a very 
artificial model. 

What can be the cause of light from one object being redshifted 
relative to another, in the many cases of high redshift or otherwise 
peculiar galaxies interacting with normal, low redshift galaxies? 
The stars, gas and dust in one object emit light redshifted relative 
to the other with which it interacts. 

This means that, for example, an atom of hydrogen in a high 
redshifted object, which makes a given transition from one energy 
state to the other, must emit or absorb a photon of lesser energy 
than the same atom would in a lower redshifted one. What determines 
the transition energy between the two atomic states? One factor is 
the relative charge between the electron and the nucleus. The other 
factor is the mass of the electron making the transition between two 
possible orbital states. Measurements of quasar spectra appear to 
rule out the possibility that the electric charges are different. 
This leaves only the mass of the electron. 

 
Arp poses the question: Is the mass of the high redshifted object
less than that of the low redshifted object?