Question regarding the arrow of time

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Discussion Overview

The discussion revolves around the concept of the arrow of time, particularly whether different regions of the universe could exhibit different arrows of time, such as forward and backward. Participants explore theoretical implications and observational consequences of such a scenario, touching on aspects of cosmology and the nature of time.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants propose the idea that the universe could have different arrows of time for different regions, suggesting a forward arrow of time in some areas and a backward arrow in others.
  • One participant speculates on the observational consequences of such differing arrows of time, including the possibility of observing matter coalescing in improbable arrangements.
  • Another participant questions the existence of an arrow of time in a vacuum, suggesting that it might depend on the type of matter present.
  • Some participants discuss the potential for gravitational effects to be observed from regions with a backward arrow of time, despite the light absorption making direct observation difficult.
  • A reference to retrocausality is made, with one participant expressing skepticism about the idea based on external sources.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility and implications of multiple arrows of time, with no consensus reached on the validity of the concept or its observational consequences.

Contextual Notes

Limitations include the speculative nature of the proposed scenarios and the lack of empirical evidence to support claims about differing arrows of time in various regions of the universe.

Nasher
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How about this idea...
With regards to this thing called, the arrow of time!

Could the universe have different arrows of time for different regions of the universe?
This regions of the universe where the Earth is, the arrow of time is going say forward.

Could there be other far off regions of the universe that have the arrow of time going backwards?

Imagine if the universe was composed of a forward arrow of time sub-universe and a backward arrow of time sub-universe superimposed upon each other!

If there were galaxies in regions of the universe that have the arrow of time going backwards,
from our perspective instead of the stars in those galaxies emitting light, they would be absorbing light,
and therefore their light would not be visible to us here in this forward arrow of time region of the universe.
 
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What would be the observational consequences [to us] of these different 'arrows of time'?
 
The observational consequence would be if we went somewhere and found clouds of random looking debris and gas coalescing into unlikely arrangements, light bizarrely focusing itself onto dwarf stars until they bloat and evaporate into uniform gas clouds, planets with dirt that suddenly arranges itself into big living organisms that shrink and then are taken into even newer organisms..

Nothing stopping this happening, it's just incredibly improbable.

What I can't explain is why it seems our universe was far, far more improbable than that when it began (more so even than the anthropic principle justifies).
 
Last edited:
What way does the arrow of time point in a vacuum?

Could it be that there is no arrow of time in a vacuum?

Could the universe have different arrows of time for different regions of the universe depending on the type of matter there?

This regions of the universe where the Earth is, the arrow of time is going say forward, and let's call the type of matter here, forward matter.

Could there be other far off regions of the universe that have the arrow of time going backwards?
And the type of matter in those regions could be known as reverse matter.

Imagine if the universe was composed of a forward arrow of time sub-universe and a backward arrow of time sub-universe superimposed upon each other!

If there were galaxies in regions of the universe that have the arrow of time going backwards, from our perspective instead of the stars in those galaxies emitting light, they would be absorbing light, and therefore their light would not be visible to us here in this forward arrow of time region of the universe.
 
Chronos said:
What would be the observational consequences [to us] of these different 'arrows of time'?

I reckon that they would be difficult to observe because from our perspective, they would be absorbing light.

Maybe, the effects of their gravitational field could be observed.

Maybe, if theoretical physicists were to work through the mathematics, the might expect to find certain results that would be complementary to the observed structure of the universe.
 
As, it seems, do I [dismiss the idea].
 

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