Hubble constant depend on expansion model?

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Discussion Overview

The discussion revolves around whether the measured value of the Hubble constant, H_0, is influenced by the specifics of the expansion model employed. It touches on observational methods, theoretical implications, and the relationship between the Hubble constant and the Cosmological Constant.

Discussion Character

  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants propose that the Hubble constant is not dimensionless and can vary based on the units used, with different measurement methods yielding slightly different values within error bars.
  • Others argue that the value of the Hubble constant may depend on the method of measurement, suggesting that observations from the Cosmic Microwave Background could lead to different implications compared to nearby observations.
  • A later reply questions the relevance of the Cosmological Constant in this context, indicating a perceived off-topic nature of the discussion regarding its arbitrary value in Einstein's equations.

Areas of Agreement / Disagreement

Participants express differing views on the relevance of the expansion model to the Hubble constant's measurement, indicating that multiple competing perspectives remain without a clear consensus.

Contextual Notes

There are unresolved aspects regarding the dependence of the Hubble constant on the chosen expansion model and the implications of different observational methods.

johne1618
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Does the measured value of the Hubble constant, H_0, depend on the details of the expansion model one uses?
 
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The Hubble Constant is not dimensionless (i.e., it will change depending on the units you are using), I know that slightly different values have been collected depending on the method used (all within error bars), I believe that the Cosmological Constant can be given a arbitrary value in Einsteins GR equations, although there is only a small range where the value would be reasonable.

The reason I bring both up is that while the Hubble Constant is based on observation, the Cosmological Constant is based in the equations.
 
johne1618 said:
Does the measured value of the Hubble constant, H_0, depend on the details of the expansion model one uses?
That depends somewhat upon how it is measured. If it is inferred from far-away observations, such as the Cosmic Microwave Background, then the answer is yes. But our most accurate measurements of [itex]H_0[/itex] are from nearby observations where the expansion rate hasn't changed enough for it to really matter what our model of the expansion is.
 
Vorde said:
The Hubble Constant is not dimensionless (i.e., it will change depending on the units you are using), I know that slightly different values have been collected depending on the method used (all within error bars), I believe that the Cosmological Constant can be given a arbitrary value in Einsteins GR equations, although there is only a small range where the value would be reasonable.

The reason I bring both up is that while the Hubble Constant is based on observation, the Cosmological Constant is based in the equations.
What? Why are you bringing this up? Because it sounds completely off-topic to me.
 

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