Discussion Overview
The discussion centers on the concept of universal expansion and whether such an expansion would be perceptible to observers within the universe. Participants explore theoretical implications of proportional expansion of all physical dimensions and constants, as well as the relationship between local and cosmic scales.
Discussion Character
- Exploratory
- Conceptual clarification
- Debate/contested
Main Points Raised
- One participant proposes that if everything in the universe were to expand proportionately, observers would not be able to detect this change since their scales and clocks would also adjust accordingly.
- Another participant questions the definition of such an expansion, suggesting that changing the definition of units does not equate to physical expansion of the solar system.
- A participant references Dirac's Large Number Hypothesis, suggesting that if fundamental constants changed proportionally, it would go unnoticed.
- In response, another participant notes that dimensionless fundamental constants would be noticeable if they changed, as they are independent of unit systems.
- One participant raises the possibility that local systems, such as the solar system and atomic structures, could be expanding alongside the cosmic expansion, questioning how this could be detected.
- A later reply indicates skepticism about the feasibility of such an expansion, suggesting that it has been discussed frequently in the forum without resolution.
Areas of Agreement / Disagreement
Participants express differing views on the perceptibility of universal expansion, with some suggesting it would be undetectable while others argue that certain changes could be noticed. The discussion remains unresolved regarding the implications of universal expansion on local systems.
Contextual Notes
Participants highlight limitations in defining expansion and the dependence on the choice of units. There is also an acknowledgment of the complexity surrounding gravitationally bound systems and their relationship to cosmic expansion.