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Mar26-04, 08:10 AM
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Quote Quote by DrMatrix
How can the two models produce different observations when we can transform one into the other by changing the definition for our unit of length (applying a conversion)?
It is nonsense to say everything in the universe has doubled in size, because we would have to say doubled in size compared to some defined unit of length.

If we assume that rigid rods do not change length, then redshift is evidence for expanding space. If we assume that space is not expanding, then redshift is evicence that rigid rods must be shrinking. It is just two ways of expressing the same thing.
That is factually incorrect. The expansion of the universe according to the Hubble flow is NOT a change to the yardstick used to make measurements. The distance between the orbitals in an atom, for example, stay the same. It is a physical process, as of now poorly understood, and is part of the same process that yielded rapid inflation in the very early universe. Below is an excellent summary of the current state of the art on this subject:

Lineweaver and Davis: Common Misconceptions of ...Expansion of the Universe (PDF)

It is clear to me that this describes something which is far different than what you describe. If you think you can find an equivalent way to describe how shrinking gives the same effects, it will take as much analysis as is presented in the paper to convince. After all, the light we are seeing 13 billion years ago (universe was 750 million years old) is coming from object now 46 billion light years away.

I don't believe you can prepare a "shrinking" scenario which matches these results. Recall that most physicists will reject your assertion that the processes described in the citation above is equivalent to a change in the yardstick used to measure distances. Showing the kind of invariance you are attempting to assert (that you call a definition) is far from simple. Don't assume they are the same thing. You must propose a rate of change of the yardstick and fit everything together in a consistent way. I.e. show how matter shrinks while space remains constant, and that yields predictions consistent with observation.