How does the expansion of space affect the direction of time?

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Discussion Overview

The discussion explores the relationship between the expansion of space and the direction of time, including concepts such as time dilation, the effects of mass and gravity on expansion, and the possibility of time existing independently of space and motion. The scope includes theoretical and conceptual inquiries within astrophysics and cosmology.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant suggests a potential link between the expansion of space and the "arrow of time," questioning if they are directly related.
  • Another participant asserts that expansion does not cause time dilation and distinguishes between redshift and time dilation.
  • A participant inquires whether mass and gravity affect the expansion of space and its relation to time.
  • It is proposed that mass, gravity, and vacuum energy influence the rate of expansion, while time is described as a measurement rather than a direct factor in expansion.
  • Time dilation is characterized as observer-dependent, with different perceptions based on the observer's position.
  • A question is raised about the existence of time without space and motion, noting the lack of consensus on this topic.
  • Some models, including multiverse theories, suggest time could exist independently of space, while others propose that time began with the formation of space.
  • One participant references Hawking's theory, proposing that time may be a construct of human perception rather than a fundamental aspect of the universe.
  • Connections between time, space, motion, and gravity are emphasized, with a request for classification within astrophysics.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the relationship between time and space, particularly concerning the existence of time without space and the effects of expansion on time. There is no clear consensus on these issues.

Contextual Notes

The discussion includes various models and theories that are not universally accepted, highlighting the complexity and uncertainty surrounding the relationship between time, space, and motion.

Geordie Ross
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Hi, I'm new to the forum, and didn't really know where else to ask some questions, and get good answers, I'm fairly poor at mathematics, and grammar, but I have a passion for physics, astrophysics and cosmology. I have some niggling ideas and hypothesis that I can't find answers for, and I hope I don't make myself look foolish, but Einstein said he "visualised" his ideas, and I had a... "visualisation", that the expansion of space, is somehow linked to "arrow of time", in the sense of one way direction of time in large scale, could it be directly linked to expansion? And could it be linked to time dilation? Or does mass have any effect on expansion?
I'd appreciate any response, and please correct any mistakes I've made.
 
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Welcome to the forum.

Time dilation and expansion are not linked as per se. The expansion does not cause any time dilation. We do see how expansion affects the wavelength of light called redshift. However this is not the same as time dilation. Gravitational time dilation in terms of an overall average mass density isn't sufficient to cause dilation.
 
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Thanks, I appreciate the reply.
Would mass and gravity have any affect on expansion? And does expansion relate in any way to time?
 
Mass and gravity does affect expansion, so does the vacuum energy called the cosmological constant. The relation between the two are used to determine the rate of expansion. Time is only a measurement in expansion and not directly related to a direct effect on expansion

this link is related and has some further information.

https://www.physicsforums.com/showthread.php?t=688708
 
Also on time dilation, this is an observer dependent property. An outside observer will see the dilation and inside observer will see time flow normally
 
Thanks for the clarification.
One more questions, could time exist without space and motion?
 
Thats one question that has no clear consensus. There are models that say yes such as multiverse models. Others that say time started at the first moment of that space formed.

So I cannot give you a definitive answer
 
Mordred said:
Thats one question that has no clear consensus. There are models that say yes such as multiverse models. Others that say time started at the first moment of that space formed.

So I cannot give you a definitive answer

Some adhere to the Hawking theory - time being the product of our brains, simply. That there is no Newtonian "ticking clock" for the universe progression.

Could time truly exist without objects? What do current astrophysicist/astronomers have to say about this? Could you ever get indirect evidence for any viewpoint?
 
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  • #10
Chronos said:
Time, space and motion are obviously connected. Gravity is also involved in this arrangement. See comments by Sten Odenwald at https://einstein.stanford.edu/content/relativity/a11332.html
What area would this be classified under in Astrophysics? That is; space, objects and motions?.. Not just the particles, and not just motion, but also space and time.

The link was quite interesting!
 

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