Discussion Overview
The discussion centers on the necessity of accounting for Hubble Redshift when determining the rotation velocities of galaxies that exhibit keplerian motion. Participants explore whether the spatial expansion of the Universe leads to spectral shifts that create an observed asymmetry in the line-of-sight (LOS) velocities of material moving toward and away from the observer.
Discussion Character
- Exploratory
- Technical explanation
- Debate/contested
Main Points Raised
- One participant questions the need to account for Hubble Redshift effects on rotation velocities, suggesting that the expansion does not create asymmetry in the detected speeds of material moving toward and away from the observer.
- Another participant presents a hypothetical scenario to illustrate that the Doppler effects should be symmetric, regardless of the galaxy's redshift, implying that the observed wavelengths would shift similarly for both approaching and receding material.
- A third participant introduces an analogy involving helicopter blades to question whether the perceived RPM differs based on the observer's position relative to the blades' motion.
- A later reply speculates that an asymmetric phenomenon related to redshift could occur if the recession velocity of a galaxy approaches the speed of light, suggesting that material moving away could become unobservable while other parts of the system remain detectable.
Areas of Agreement / Disagreement
Participants express differing views on whether Hubble Redshift leads to asymmetry in observed velocities, with some arguing for symmetry and others suggesting potential asymmetries under specific conditions. The discussion remains unresolved.
Contextual Notes
Participants do not reach consensus on the implications of Hubble Redshift for galactic rotation curves, and there are unresolved assumptions regarding the conditions under which asymmetries might arise.