Expanding Universe: Cooling Matter, Gravity & Isotropy

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In an expanding universe, the average energy density decreases over time, but this reduction affects the space between matter rather than the matter itself, meaning distant stars do not cool. Gravity does not inherently weaken; it diminishes with distance but remains constant in strength. The concept of isotropy does not apply to the natural forces in this context. The Big Rip theory posits that gravity may weaken due to cosmic acceleration, potentially affecting other fundamental forces as well. Overall, while the universe expands, the fundamental properties of matter and gravity remain unchanged at a local level.
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in an expanding universe is all matter cooling? also, is has gravity become weaker over large distances? does isotrophy apply to the natural forces?
 
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In an expanding universe, the average energy density decreases over time. But this decrease is over all of spacetime, it does not affect matter. So, distant stars do not 'cool' over time, just the space in between. Similarly, gravity does not change, it merely diminishes as distance increases. 'Isotrophy' has nothing to do with the 'natural forces'.
 
Chronos said:
In an expanding universe, the average energy density decreases over time. But this decrease is over all of spacetime, it does not affect matter. So, distant stars do not 'cool' over time, just the space in between. Similarly, gravity does not change, it merely diminishes as distance increases. 'Isotrophy' has nothing to do with the 'natural forces'.

the big rip theory suggests gravity will weaken due to acceleration. presumably the other forces as well.
 

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