Investigating the Constancy of Light-Speed: A Call to Greater Knowledge

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In summary, the author of this article claims that recent measurements of the speed of light have shown that it is slowing down, and this could be a significant problem for inflationary cosmology.
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I'm sure this forum is frequented by people claiming to have proven or disproven aspects of relativity. In this case I am appealing to those with greater knowledge than mine, specifically in regards to the constancy of light-speed. The case has been made to me that the speed of light is not constant, and has changed measurably over the last 250 years. Essentially, I have been provided a link by a friend and co-worker which, to the lay-person (myself), seems to present a convincing case that the speed of light is variable.

The article, ( [Broken] by Barry Setterfield), contains compiled data from nearly 300 years of light-speed measurements that indicate that the speed of light is slowing down. The article claims that measurements of light in the past have always shown it to be faster than it is today, without exception. Obviously a changing speed of light would call into question a great many things, in particular, the use of light as a constant for measuring speed and distance.

Following that up was another article calling into question the gradual redshift of regressing celestial light sources:(On the Quantization of the Red-Shifted Light from Distant Galaxies by Mark Stewart), which cites the observations of rotating galaxies as contradictory evidence of a gradual redshift curve, and therefore calls into question the dependability of redshift as a measurer of speed and distance in regressing objects which, as I understand, is an important support for inflationary cosmology.

Here is a quote from the article which provides apparently specific information regarding unusual redshift measurements in gravitationally bound galaxies:
"Two galaxies physically associated with one another offer the ideal test for redshift quantization; ...

...If we observe many pairs covering a wide range of viewing angles and orbital geometries, the expected distribution of redshift differences should be a smooth curve. In other words, if redshift is solely a Doppler effect, then the differences between the measured values for members of pairs should show no jumps.

But this is not the situation at all. In various analyses the differences in redshift between pairs of galaxies tend to be quantized rather than continuously distributed. The redshift differences bunch up near multiples of 72 km per second. Initial tests of this result were carried out using available visible-light spectra, but these data were not sufficiently accurate to confirm the discovery with confidence. All that changed in 1980 when Steven Peterson, using telescopes at the National Radio Astronomy Observatory and Arecibo, published a radio survey of binary galaxies made in the 21-cm emission of neutral hydrogen.


Red shift differences between pairs group around 72, 144, and 216 km per second. Probability theory tells us that there are only a few chances in a thousand that such clumping is accidental. In 1982 an updated study of radio pairs and a review of close visible pairs demonstrated this same periodic pattern at similarly high significance levels.

Radio astronomers have examined groups of galaxies as well as pairs. There is no reason why the quantization should not apply to larger collections of galaxies, so redshift differentials within small groups were collected and analyzed. Again a strongly periodic pattern was confirmed.

He [Mark Stewart] provides further evidence collected from observations of dwarf irregular galaxies and draws the conclusion: "Current cosmological models cannot explain this grouping of galaxy redshifts around discrete values across the breadth of the universe. As further data are amassed the discrepancies from the conventional picture will only worsen. If so, dramatic changes in our concepts of large-scale gravitation, the origin and "evolution" of galaxies, and the entire formulation of cosmology would be required."

With my limited personal knowledge of modern physics and cosmology I cannot myself determine the truth of this article. If any of you can point out the fallacies, support the conclusions, or otherwise provide articles or information that might confirm or contradict the evidence or conclusions of this article and others claiming errancy in redshift interpretation I am interested and grateful for your time.

As many of you have guessed, this article is being used as a support for a young or steady state universe in a likely attempt to reconcile the contradictory evidence of (old universe) inflationary cosmology with biblical time frames (in a word: Creationism). I don't often consider arguments that start with a conclusion and work backwards, but in all fairness one must be open to contrary beliefs and therefore I am giving this argument real consideration.

I immediately returned to my college Astronomy textbook for answers. I found plenty of evidence to support a gradual redshift, but it did not address this specific issue -- leading me to believe that the authors did not deem it worthy of consideration, simply overlooked it, or intentionally ignored it (supressed by the global scientific conspiracy [j/k]:)) I came across this site while looking for more information, I am hoping some of you may have addressed this before or have knowledge in this area. Any help is very much appreciated.

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  • #2
There is speculation of a changing speed of light but the difference would not be measurable over the past 300 years. The accuracy of the initial light speed tests simply wasn't good enough to measure it. Michelson's measurement 120 or so years ago was probably the first reasonably accurate one.
  • #3
Question: what are the comparitve results since 12o years?
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I read that in 2002, in one university in Sydney, some scientist made observations in an ancient object in the sky (I don't know what kind of object) and they saw that the fine structure constant could be lower than today various millions of years ago. This would imply that the charge of electron or "c" have changed. They supposed the change was due "c" and was higher than today various millions of years ago.

Sorry I don't have any link.

1. What is the purpose of investigating the constancy of light-speed?

The purpose of this investigation is to better understand the fundamental laws of the universe and how they shape our understanding of reality. By studying the constancy of light-speed, we can gain insights into the nature of space, time, and the fabric of the universe itself.

2. How is the constancy of light-speed measured?

The constancy of light-speed is measured using a variety of scientific methods, including experiments with light beams and mirrors, observations of celestial bodies, and advanced mathematical calculations. These methods allow scientists to accurately determine the speed of light and test its consistency under different conditions.

3. What evidence supports the constancy of light-speed?

There is a vast amount of evidence supporting the constancy of light-speed, including the results of experiments and observations conducted over hundreds of years. One of the most significant pieces of evidence is the fact that the laws of electromagnetism, which govern the behavior of light, are consistent and universal. Additionally, the predictions of Einstein's theory of relativity have been repeatedly confirmed through experiments and observations.

4. Are there any exceptions to the constancy of light-speed?

To date, there have been no exceptions to the constancy of light-speed observed or confirmed by scientific evidence. While some theories and hypotheses have been proposed, none have been able to withstand rigorous testing and scrutiny. The overwhelming body of evidence supports the idea that the speed of light is a universal constant.

5. How does the constancy of light-speed impact our understanding of the universe?

The constancy of light-speed is a fundamental principle of modern physics and has had a profound impact on our understanding of the universe. It has led to the development of the theory of relativity, which has revolutionized our understanding of space, time, and gravity. The constancy of light-speed also plays a crucial role in many technologies, such as GPS systems and telecommunications, demonstrating its practical applications in our daily lives.

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