Not at all. The alleged acceleration results from the inadequate Doppler's equation used for the redshift. Instead, the exponential function need be used: exp(-v/c). For more details, please see the attached file.

Dear Preston Guynn.

You ask: Do you have a link to 'Sauver les apparences Sur la notion de théorie physique de Platon à Galilée'?

Two copies are on archive.org. The links are:

https://archive.org/details/rcin.org.pl.WA35_19145_6365_Sozein_14003/page/n9/mode/2up

https://archive.org/details/szeintaphainome00duhegoog

Duhem was elaborating a remark in Ptolemy's Almagest. The quote below is from Toomer's Almagest edition, beginning at p. 600, with the source of the `save the phenomena' phrase in bold:

Now let no one, considering the complicated nature of our devices, judge such hypotheses to be over-elaborated. For it is not appropriate to compare human [constructions] with divine, nor to form one’s beliefs about such great things on the basis of very dissimilar analogies. For what [could one compare] more dissimilar than the eternal and unchanging with the ever-changing, or that which can be hindered by anything with that which cannot be hindered even by itself? Rather, one should try, as far as possible, to fit the simpler hypotheses to the heavenly motions,' but if this does not succeed, [one should apply hypotheses] which do fit. For provided that each of the phenomena is duly saved by the hypotheses, why should anyone think it strange that such complications can characterise the motions of the heavens when their nature is such as to afford no hindrance, but of a kind to yield and give way to the natural motions of each part, even if [the motions] are opposed to one another?

Preston Guynn

Thank you for your insightful immediately preceding commentary.

On `saving the phenomena' as being similar to Occam's razor, I agree with you. The source of the expression in Ptolemy seems to say that theory should conform to observation. The problem is not Ptolemy's expression, the problem is that Ptolemy erroneously accepted the prevalent assumption that all celestial motion must be circular. On that assumption, he adapted planetary circular motion around Earth using epicycles. His expression of saving the phenomena is not problematic; rather, he assumed that he had a good handle on the phenomena, that celestial objects always follow circular paths.

Thanks again.

Regards

Bob Shour

Since the Universe is observed to be accelerating, and acceleration and gravity are equivalent from the equivalence principle, dark energy might be responsible for gravity itself, even though it would be fundamentally repulsive. It might only appear attractive at smaller scales, as with the construction of a common sponge, where the expanding voids are the active portion. For example: (7) Is "dark energy" the basis of gravity? | LinkedIn

Dear Preston Guynn,

In responding to Robert Shour, you noted:

‘When you write "Is positing accelerating space a way to save the phenomena behind dark energy", the phrasing and meaning are both problematic. The observation/measurements involve luminosity and redshift.’

This was followed by your question:

“So what is the phenomena being saved by positing accelerating space?”

I’ll attempt an answer.

First, we don’t know, for sure, the explanation for observed accelerating space. A clue here is that decelerating space expansion in the early universe was due to more concentrated matter at the time, so something in the opposite sense is responsible for the observed acceleration in recent time. Here empiricism/observation may be insufficient to finally answer the question. More to the point, Eddington reputedly advised to never credit any observational/experimental finding until it has been confirmed by theory (partially in jest perhaps). And so, just as the explanation of “dark matter” waits decade after decade for the definitive theory, the explanation for “dark energy” similarly waits.

But as to “…what is the phenomena being saved by positing accelerating space (or “cosmic acceleration)”, it may be that the explanation requires a correspondence-principle compliant extension/revision of relativity theory—i.e., one that preserves the successes of twentieth century special/general relativity while accommodating, e.g., (time-averaged) IRF-equivalent two-way speeds of light in the twenty-first century.

Returning to the original question of the discussion, “dark energy” can be considered a place holder that “[saves] the phenomena”—until such time that deeper relativity theory reveals the hidden phenomena. But special and general relativity stand as very tall hurdles that must be cleared, with the crucial help of empiricism to allow this to happen.

Regards,

Thomas E. Chamberlain

There is no dark or white matter, which a simple speculation. Matter is universal in nature, has no colors or spectral value