Do we need Dark Matter or are we just time blind

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Discussion Overview

The discussion revolves around the necessity of dark matter in explaining the observed velocities of stars near the center of the Milky Way galaxy. Participants explore the implications of gravitational time dilation and whether it could account for the discrepancies in expected versus observed star velocities. The conversation touches on theoretical interpretations, observational evidence, and the potential for alternative explanations.

Discussion Character

  • Debate/contested
  • Exploratory
  • Technical explanation

Main Points Raised

  • Some participants propose that the apparent velocities of stars near black holes may be influenced by time dilation effects, suggesting a form of "time blindness" in measurements taken from Earth.
  • Others argue that the observed velocities of stars closer to the center of the Milky Way align with predictions based on visible matter distribution, challenging the initial claim about their unusual speeds.
  • It is noted that gravitational time dilation is minimal except in extreme gravitational fields, such as those near black holes, and may not significantly affect the measurements in question.
  • Some participants assert that the evidence for dark matter is robust and supported by various observations, indicating that time dilation cannot account for the missing mass problem observed in galaxy rotation curves.
  • Concerns are raised about the assumptions underlying the calculations of mass and velocity, questioning whether gravitational time dilation could lead to misinterpretations of mass estimates.

Areas of Agreement / Disagreement

Participants express differing views on the role of dark matter and the significance of gravitational time dilation. While some maintain that dark matter is necessary to explain observed phenomena, others suggest that time dilation could provide an alternative explanation. The discussion remains unresolved, with multiple competing perspectives presented.

Contextual Notes

Limitations include the dependence on specific gravitational models and the assumptions made regarding the effects of time dilation in various contexts. The discussion highlights the complexity of measuring velocities in gravitational fields and the potential for significant errors if time frames are not accurately accounted for.

  • #31
The baryon mass fraction of the universe has been measured with great precision by a number of studies [Planck, WMAP, BAO] which rules out any significant unaccounted contributions from black holes. For further discussion see https://ned.ipac.caltech.edu/level5/Peebles2/P5_2.html
 

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