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What do you mean by "initial size of the universe"? The scale factor is always zero at the start of an expanding universe.hedgehug said:
Does the scale factor need to be normalized?
- Context: Undergrad
- Thread starter hedgehug
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Discussion Overview
The discussion revolves around the normalization of the scale factor in cosmology, particularly in relation to the calculation of the radius of the observable universe. Participants explore the implications of redefining the scale factor and its effect on integrals used in cosmological models, including the FLRW metric.
Discussion Character
- Debate/contested
- Mathematical reasoning
Main Points Raised
- Some participants propose that redefining the scale factor should not change the result of the integral for calculating the radius of the observable universe, while others argue it will change the numerical value due to a change in distance units.
- There is a discussion about the units of speed (c) and the integration limits, with some participants suggesting that the units must remain consistent with the chosen distance and time units.
- One participant questions whether the scale factor is normalized, suggesting that the distance unit must be inversely proportional to the observed redshift plus one, which could imply normalization.
- Another participant clarifies that normalization is a matter of convention and not dictated by physics, indicating that different choices for the scale factor and distance units can yield consistent results.
- There is a suggestion that the product of the scale factor and the distance unit can be normalized, leading to a debate about whether this is equivalent to normalizing the scale factor itself.
- Some participants discuss the implications of using different definitions for the scale factor, including the possibility of generalizing definitions that do not require the scale factor to equal one at the present time.
Areas of Agreement / Disagreement
Participants express differing views on whether redefining the scale factor constitutes normalization and whether the integral's numerical value changes with unit rescaling. No consensus is reached on these points, indicating ongoing debate.
Contextual Notes
Participants highlight that the definitions and conventions used in cosmology can significantly affect the interpretation of results, and the discussion includes various assumptions about units and their relationships.
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