Is Time Relative or Absolute in Spacetime?

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Discussion Overview

The discussion centers on the nature of time in the context of spacetime, specifically addressing whether time is relative or absolute. Participants explore implications for cosmological models, the relationship between time and space, and the effects of motion on time perception.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants question the consequences of background dependency in cosmological horizon modeling.
  • One participant describes time as a temporal dimension at right angles to spatial dimensions, suggesting that movement through time necessitates movement through space.
  • Another participant argues that time dilation is an illusion caused by the stretching of one spatial dimension relative to an unstretched temporal dimension.
  • A different viewpoint emphasizes that in an observer's rest frame, they are stationary in space while moving through time, contrasting this with how other inertial observers perceive motion.
  • It is noted that time and space dilation, as described by Lorentz transformations, are not illusions, as they have real physical consequences, such as the extended lifetime of cosmic ray muons.
  • One participant asserts that true time within spacetime is absolute and unchanging, while relative time varies between observers in relative motion.
  • Another participant challenges the notion of an unmoving mass in spacetime, pointing out that all masses are in motion relative to one another, and questions how "true time" can be measured.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the nature of time, with no consensus reached on whether time is absolute or relative. The discussion remains unresolved with differing interpretations of time's properties.

Contextual Notes

Participants highlight limitations in defining "true time" and the implications of motion on time measurement, indicating a dependence on reference frames and the absence of a universal frame of reference.

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What are the consequences for Background dependancy in Cosmological Horizon modelling?
 
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time is a temporal dimension of spacetime at right angles to the 3 spatial dimensions of spacetime

if you move through time, you also move through space

so you can't do one without the other


time dilation is an illusion caused by one spatial dimension being stretched
(for the observer) relative to the temporal dimension which remains unstretched
 
1) In your rest frame you are standing still, and moving through time, but not through space. Of course other intertial observers see it differently. They see you as moving through both time and space.

2) Time and space dilation through the Lorentz transformations are not illusions for two reasons: first because there is no unversal frame in which the "true" situation could be described, so all we ever have is the relative situation in which the dilations apply, and secondly because the dilations make real physics happen (e.g. the extended lifetime of the cosmic ray muon).
 
in reality there is no such thing as an unmoving mass in spacetime

the Earth and everything on it is moving at 30000 m/s around the sun

the sun and all it's planets are moving around a spiral galaxy


true time (within spacetime) is absolute and unchanging - whilst relative time is variable only between observers in relative motion
 
Last edited:
energia said:
in reality there is no such thing as an unmoving mass in spacetime
In both Einstein's and Galileo's relativity, you are allowed to define yourself as being stationary by centering a reference frame around yourself.
true time (within spacetime) is absolute and unchanging - whilst relative time is variable only between observers in relative motion
How or in what frame do you measure "true time" and doesn't this statement (about motion or lack thereof) contradict your first?
 

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