As I understand it, the evidence for this is the red shift seen in the spectrum of distant galaxies, the more distant the galaxy the greater the red shift in its spectrum, with due allowance for variations caused by other, relatively minor, movements of the closer galaxies.
There is no doubt that expansion would cause such a red shift, by the well-known Doppler effect. I am (but see note below) less convinced that this is the only possible explanation.
I have had for many decades now (in fact, since I first learnt a little of the subject as a physics student) the germ of an idea of an alternative way in which a red shift proportional to distance, and detectable only over inter-galactic distances, might occur. Unfortunately I have neither the mathematical skills, the up-to-date experimental knowledge nor the time to investigate the idea properly. I would hope that someone with these facilities might take me seriously enough to look at the experimental evidence to see if it is at least compatible with it. If it is, then theoreticians should consider in more detail than I am capable of doing, just how such a process might work and its implications for other aspects of fundamental physics at the particle level.
The basis of my thinking on the matter depends on a consideration of the relationship between the colour of light and the energy transmitted. Normally, thinking in terms of light as a wave for convenience, the energy transmitted is proportional to the frequency as well as depending on the amplitude. All normal methods of reducing the energy of a light beam rely in effect on reducing the amplitude of the wave rather than by changing its frequency. In essence, my proposal is that some mechanism may exist (I cannot even conjecture as to its nature) which causes the energy in a light beam to be reduced by reducing its frequency (i.e. by causing a red shift), and that this mechanism takes place as light travels through inter-galactic space. It may well always take place whenever light travels, but the magnitude involved is so small that only over such vast distances could it be detectable.
It could be therefore, that although the anomalies in red shift attributed to local relative movements of nearby galaxies is caused by Doppler effect, the more general (and in terms of fundamental theory, more important) increase in red shift with distance may have nothing to do with movement at all.
If I am right, (and it is admittedly no more than an improbable hypothesis), then the universe is not expanding, the "Big Bang" never happened, and the search for all the "missing mass" of the universe is a wild goose chase.
I know there is the great gap in the idea in terms of what kind of mechanism could cause such an effect, but Newton and his contemporaries would have said the same about the consequencies (such as time dilation, etc.) of modern theories of relativity. Did that make them right?
I think someone should at least look at the idea in sufficient depth to see if it is at all feasible. I will not be convinced that the expansion theory has any better foundation than old orthodoxies such as phlogiston, earth centred universe, flat earth, Newtonian mechanics, etc. until this has been done.
Nico Benschop has reached a similar conclusion, and put forward some aspects of a possible mechanism. His web page contains the material from a newsgroup discussion of that and related topics.
However, I have (August 2002) been advised by Brian Steadman that:
"the idea has been proposed by several people in the past. It is usually called 'tired light' theory and is discussed, and more or less demolished, on p775 of Gravitation by Misner, Thorne and Wheeler. The book is one of the 'bibles' of general relativity and is probably kept in most reasonable-sized libraries."
I haven't yet had an opportunity to look at the book, but according to this report the thought has been fully considered and I can now forget it.
On the other hand, even more recently I have had my attention drawn to Michael Lewis's web site, which gives a detailed mathematical analysis of one way in which it could happen. Again, I haven't yet had time to study it in detail, but will certainly be doing so.
Please let me know what you think.
My own proposal for the measurement of coolth (last updated 24th July 1998)
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