Space + time = space time? then....

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Discussion Overview

The discussion revolves around the relationship between the expansion of space and the nature of time, particularly in the context of Einstein's theory of relativity. Participants explore whether an accelerating expansion of space implies an acceleration of time and how this might relate to concepts like the speed of light and cosmological models such as Guth's inflation theory.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • One participant questions if the accelerating expansion of space implies that time is also accelerating, suggesting that this could mean time passed slower in the past.
  • Another participant humorously asserts that "time is expanding" by referring to the future, but does not elaborate on the implications of acceleration.
  • Some participants express skepticism about the concept of "accelerating time," stating it lacks clear meaning and questioning how such a phenomenon could be measured.
  • A participant explains that while space expands, the notion of time does not change in the same way, referencing the FLRW solution and the scale factor of space.
  • There is a discussion about measuring time in relation to the speed of light and how expanding distances might affect this measurement.
  • One participant introduces the idea of time dilation when looking back towards the Big Bang, which is acknowledged but clarified as being referred to as redshift in cosmology.

Areas of Agreement / Disagreement

Participants generally do not agree on the implications of space expansion for the nature of time, with multiple competing views expressed regarding the meaning and measurement of time in this context.

Contextual Notes

The discussion includes various assumptions about the nature of time and space, and the implications of relativity, which are not fully resolved. The relationship between the expansion of space and the concept of time remains unclear and contested among participants.

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TL;DR
probably a daft question asked before. but. if space is expanding at an accelerating rate would that mean time is accelerating too?
probably a daft question asked before, but.

if space is expanding at an accelerating rate would that mean time is accelerating too?.
after all Einstein* claims and the maths seems to say that space and time are the same thing, ie space-time.
so if space is expanding faster and faster shouldn't that mean time is also?.
and as a result in the past time passed slower?.

would this also mean that the speed of light is only constant relative to the space time its traveling through?.

if this is true would it negate guths inflation model?

if not please feel free to pontificate, postulate and reason ;)

*edit
 
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Time is expanding. We call it the future.
 
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yes its expanding. but at an accelerating rate?.
 
HEXiT said:
yes its expanding. but at an accelerating rate?.

The expansion of space means that distances between points increases over time. The rate at which this expansion is happening is increasing over time, which we call accelerating expansion. Accelerating time doesn't have any meaning that I can see.
 
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HEXiT said:
so if space is expanding faster and faster shouldn't that mean time is also?

I don't know what this means. I suspect you don't either. Can you describe how such a thing would be measured?
 
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yes but we measure time over a given distance via the speed of light, but that distance is always getting bigger due to expansion.
 
HEXiT said:
Ernestine
Is that Albert's sister?
HEXiT said:
if space is expanding at an accelerating rate would that mean time is accelerating too?.
No. I'm not sure "time accelerating" really makes sense. The FLRW solution includes the scale factor of space changing as a function of time, but it doesn't affect its notion of time.
 
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HEXiT said:
Summary:: probably a daft question asked before. but. if space is expanding at an accelerating rate would that mean time is accelerating too?

Einstein* claims and the maths seems to say that space and time are the same thing, ie space-time.
so if space is expanding faster and faster shouldn't that mean time is also?.
It may not be immediately obvious from your exposure to relativity, but it is a very geometric theory. Time and space aren’t the same thing, they are different directions in the same space.

The idea that space is expanding means that the universe is shaped like a trumpet. It has a small end and a big end. Saying that the trumpet expands as you go along the trumpet doesn’t mean that the length changes, it just means that the shape is not a cylinder but something more interesting.
 
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If you were to look back in time towards the big bang, wouldn't you measure time dilation?
 
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Andrew Wright said:
If you were to look back in time towards the big bang, wouldn't you measure time dilation?
Yes, but in cosmology they call it redshift
 

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