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The speed of time


AbstractDreamer
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1 hour ago, swansont said:

Except it’s not dependent upon distance when the distance is small.

Then neither is a change in the time metric.

1 hour ago, swansont said:

Testability is a requirement for it to be scientific 

Then String Theory is not scientific, but it still being explored.

1 hour ago, swansont said:

Gravity. As has repeatedly been explained.

Then gravity is also the mechanism why there is no observed change in the time metric where gravity is significant, as I have repeatedly explained through inheritance.

1 hour ago, swansont said:

Nothing in science has definitive proof, so this is an artificial objection.

Then a falsification will suffice.

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9 hours ago, AbstractDreamer said:

That is, the redshift shows that the receeding exceeds the speed of light, which violates GR, so there must be another mechanism at play;

It doesn't violate GR. It is a prediction of GR given the values of several measured variables.

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8 hours ago, AbstractDreamer said:

Then gravity is also the mechanism why there is no observed change in the time metric where gravity is significant, as I have repeatedly explained through inheritance.

Do we independently observe gravity affecting time (or not affecting time) in this manner? Is there a theoretical basis for this? If not, you’re basically saying it’s magic.

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8 hours ago, md65536 said:

It doesn't violate GR. It is a prediction of GR given the values of several measured variables.

Ok I accept that apparent super luminal recession is a prediction of GR given the FLRW solution, and not a violation of GR under that interpretation.  And that solution allows the metric of space to expand at any speed.

The cosmological constant was supposed to provide a static solution to the field equations.  Redshift was then discovered in spiral nebulae. Lemaitre proposed a spatially expanding universe, deriving the Friedman equations with a parameter for the scale factor of expansion, and calculating Hubble's law.  Hubble then provided experimental observation evidence to support Hubble's law describing a relationship between the redshift measurements and distance from Earth.

Why have we not proposed a spatially and temporally expanding universe to explain redshift?  I dont see why it's unreasonable. 

You cant use the FLRW solution to explain why the universe expands only spatially, because the FLRW solution IS the interpretation of a universe that expands only spatially.  If you question the premise of a universe that expands only spatially, you cant use FLRW solution to falsify that question.

 

1 hour ago, swansont said:

Do we independently observe gravity affecting time (or not affecting time) in this manner? Is there a theoretical basis for this? If not, you’re basically saying it’s magic.

No, because it's an affect on the metric of time is not measureable (AFAIK).  

On the other hand, we have the observation that gravity affects space expansion.  Under what mechanism?  Magic?  Space expansion is a stretching of the metric.  Gravity, AFAIK, affects the curvature and coordinate values of spacetime, but does not stretch the metric.  Hence why gravity is bounded by causality and the speed of light, and space expansion is not.

Lemaitre's theoretical basis for space metric expansion was redshift measurements

My theoretical basis for time metric contraction is redshift measurements.

Sure he managed to derive actual solutions.

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43 minutes ago, AbstractDreamer said:

 

No, because it's an affect on the metric of time is not measureable (AFAIK).  

On the other hand, we have the observation that gravity affects space expansion. 

We observe that gravity negates the expansion; there is no corresponding redshift. Gravity is an interaction that is experimentally confirmed. 

You claim is that the effect on time is measurable as it is responsible for the redshift. 

 

43 minutes ago, AbstractDreamer said:

Under what mechanism?  Magic?  Space expansion is a stretching of the metric.  Gravity, AFAIK, affects the curvature and coordinate values of spacetime, but does not stretch the metric.  Hence why gravity is bounded by causality and the speed of light, and space expansion is not.

Lemaitre's theoretical basis for space metric expansion was redshift measurements

My theoretical basis for time metric contraction is redshift measurements.

Sure he managed to derive actual solutions.

So why isn’t the time metric contracting uniformly, if there is no change in scale?

How does GR support the static (or contracting) universe that must result?

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Just now, swansont said:

We observe that gravity negates the expansion; there is no corresponding redshift. Gravity is an interaction that is experimentally confirmed. 

How exactly does gravity negate expansion, knowing that expansion is a change in the metric and gravity is not?

1 minute ago, swansont said:

You claim is that the effect on time is measurable as it is responsible for the redshift. 

No.  My claim is that redshift could be due to BOTH a spatial AND temporal adjustment.  If there was no spatial adjustment, then yes, perhaps you can deduce the redshift is entirely due to a temporal change, and to this end, it might be measurable.  But I'm not claiming exactly how much of the redshift is due to spatial or temporal expansion.  My claim is that some of the redshift could be due to change in the temporal metric, and why is that not a possibility.

My claim is also that a change in the metric of time could be measured, if there is a way to "untrap" a frame of reference from the same moment of time as the observation, or vice versa.  Which AFAIK is not possible, but I dont know what might be possible in the future.

10 minutes ago, swansont said:

So why isn’t the time metric contracting uniformly, if there is no change in scale?

I'm not claiming there is no change in scale.

13 minutes ago, swansont said:

How does GR support the static (or contracting) universe that must result?

We find solutions where redshift can be explained via not just a spatial expansion, but a spatial AND temporal expansion.

The term time-metric-contraction might be imprecise.  I simply used the word "contraction" to conceptualise a rotation that is symmetrical to expansion.

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3 hours ago, AbstractDreamer said:

How exactly does gravity negate expansion, knowing that expansion is a change in the metric and gravity is not?

In Newtonian terms it’s an attractive force.

 

3 hours ago, AbstractDreamer said:

No.  My claim is that redshift could be due to BOTH a spatial AND temporal adjustment.  If there was no spatial adjustment, then yes, perhaps you can deduce the redshift is entirely due to a temporal change, and to this end, it might be measurable.  But I'm not claiming exactly how much of the redshift is due to spatial or temporal expansion.  My claim is that some of the redshift could be due to change in the temporal metric, and why is that not a possibility.

So it’s an even weaker claim, since you acknowledge that expansion happens.

So how does gravity eliminate redshift?

 

3 hours ago, AbstractDreamer said:

My claim is also that a change in the metric of time could be measured, if there is a way to "untrap" a frame of reference from the same moment of time as the observation, or vice versa.  Which AFAIK is not possible, but I dont know what might be possible in the future.

So we can measure expansion, owing to redshift but not time effects? 
If it’s not testable, it’s not science.

 

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On 9/29/2022 at 4:40 PM, swansont said:

In Newtonian terms it’s an attractive force.

Space expansion is not modelled in Newtonian physics.  In Relativistic physics, gravity is a curvature of spacetime 4d manifold, and space expansion is a stretching of only the 3d space metric.   How does curvature affect spatial expansion?

On 9/29/2022 at 4:40 PM, swansont said:

So it’s an even weaker claim, since you acknowledge that expansion happens.

How exactly is it an even weaker claim, even if I acknowledge that expansion happens?

And No.  I don't acknowledge that expansion must happens.  I acknowledge cosmological redshift is measured.  I acknowledge spatial expansion it is a viable interpretation of redshift.  It is apparent you are the one that adamantly believes it expansion happens, and perhaps evidentially so.  But you need to separate your beliefs, from mine. 

 

On 9/29/2022 at 4:40 PM, swansont said:

So how does gravity eliminate redshift?

Space expansion is a proposal - an interpretation - based on cosmological redshift not relativistic or gravitational redshift.  Your answer, that gravity is an attractive force under Newtonian physics is nonsense when talking about cosmological redshift.  There's no effect of gravity in cosmological redshift.

Hubble's Law describes cosmological redshift is related to proper distance and time (Hubble parameter), and NO gravity factors.   The FLRW metric describes space expansion is due to proper distance and time, and again NO gravity factors   Time metric contraction is related to distance not gravity (me).   

 

On 9/29/2022 at 4:40 PM, swansont said:

So we can measure expansion, owing to redshift but not time effects? 
 

No. Ill say it again as pedantically as possible, might just work eventually.

IF we interpret the cosmological redshift effect as spatial expansion and zero temporal expansion, then the cosmological redshift effect is all due to spatial expansion, according to Hubble Law and FLRW metric.  In this case the redshift represents only spatial expansion, and as such it is a measurement of spatial expansion.

IF we interpret the cosmological redshift effect as partial spatial AND partial temporal expansion, then the cosmological redshift effect is NOT all due to spatial expansion.   In this case cosmological redshift represents more than just spatial expansion, and as such its measurement cannot wholly be attributed to spatial expansion.

On 9/29/2022 at 4:40 PM, swansont said:

If it’s not testable, it’s not science.

Like I said before.  We can argue whether or not its testable later.  We don't know if its untestable right now.  Lack of testability hasn't stopped ideas in String Theory.

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1 hour ago, AbstractDreamer said:

Space expansion is not modelled in Newtonian physics.  In Relativistic physics, gravity is a curvature of spacetime 4d manifold, and space expansion is a stretching of only the 3d space metric.   How does curvature affect spatial expansion?

You ask as if you don’t know the answer, despite it being given multiple times.

YOU DON’T HAVE EXPANSION WHEN THE CURVATURE IS LARGE ENOUGH.

 

1 hour ago, AbstractDreamer said:

How exactly is it an even weaker claim, even if I acknowledge that expansion happens?

Because now you aren’t swapping this time oddity for expansion, you say it’s there in addition. Without any theory to predict it, and no way to test it. It’s completely ad-hoc, and science routinely rejects ad-hoc explanations.

 

1 hour ago, AbstractDreamer said:

And No.  I don't acknowledge that expansion must happens.

Make up your mind. At the very least you need to be consistent.

1 hour ago, AbstractDreamer said:

  I acknowledge cosmological redshift is measured.  I acknowledge spatial expansion it is a viable interpretation of redshift.  It is apparent you are the one that adamantly believes it expansion happens, and perhaps evidentially so.  But you need to separate your beliefs, from mine. 

Apparently you believe it too. At least some of the time.

 

1 hour ago, AbstractDreamer said:

Space expansion is a proposal - an interpretation - based on cosmological redshift not relativistic or gravitational redshift.  Your answer, that gravity is an attractive force under Newtonian physics is nonsense when talking about cosmological redshift.  There's no effect of gravity in cosmological redshift.

You didn’t ask about redshift. I didn’t answer about redshift. You asked about negating expansion.

 

1 hour ago, AbstractDreamer said:

Lack of testability hasn't stopped ideas in String Theory.

String theory at least has math and a theoretical basis.

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9 hours ago, swansont said:

You ask as if you don’t know the answer, despite it being given multiple times.

YOU DON’T HAVE EXPANSION WHEN THE CURVATURE IS LARGE ENOUGH.

I wouldn't ask if I knew the answer.  That's the nature of asking questions.   You answer as if you aren't reading the question, despite it being asked multiple times.  Hubble's law

v=H_{0} D
v = recessional velocity
H_{0} = Hubble's constant
D = proper distance

Where is the effect of curvature on recessional velocity?  In this equation that shows the direct relationship between recessional velocity (cosmological redshift interpreted as spatial expansion) and distance, where does gravity come into the picture?   

10 hours ago, swansont said:

Make up your mind. At the very least you need to be consistent.

Apparently you believe it too. At least some of the time.

I've been very consistent. There is nothing I can do about other people choosing to be inconsistent with understanding what I'm saying.   It's about whether or not cosmological redshift can have an interpretation that includes a temporal contraction/expansion.   It's NOT about if I believe that it does or does not.  What I believe is irrelevant.  Science is not about faith.

 

10 hours ago, swansont said:

You didn’t ask about redshift. I didn’t answer about redshift. You asked about negating expansion.

I never asked about negating expansion.  You answered that gravity negates expansion. 

On 9/29/2022 at 12:25 PM, swansont said:

We observe that gravity negates the expansion; there is no corresponding redshift. 

Your answer was in response to my supposition that gravity affects space expansion... which was simply a juxtaposition of your previous question about gravity affecting time, which to me seemed to carry an implicit meaning that gravity DID indeed affect space expansion, which I didn't know then and latter asked about.

On 9/29/2022 at 10:09 AM, swansont said:

Do we independently observe gravity affecting time (or not affecting time) in this manner?

On 9/29/2022 at 11:33 AM, AbstractDreamer said:

On the other hand, we have the observation that gravity affects space expansion.


You are looking at the FLRW metric model and the evolution of the Universe as a whole; a model that assumes a spatial expansion interpretation of comoslogical redshift and a flat time metric, to explain why gravity negates spatial expansion and not the time metric, and describe how the universe evolved.   You're using a theory to justify its assumptions.  That is a logical fallacy.

Not only that, I'm asking specifically about cosmological redshift interpretation, not gravitational or relativistic redshift.

10 hours ago, swansont said:

String theory at least has math and a theoretical basis.

The point was about testability or non-testability.   Are you conceding that your argument that my proposal is untestable is moot at this stage?

In response to my lack of maths, I'm not denying that.   I don't think it is a reason to dismiss the idea entirely at such an early conceptual stage.

In response to a theoretical basis, your arguments thus far have largely missed the mark.  I'm questioning the completeness of a spatial expansion interpretation of cosmological redshift.  Your arguments supporting spatial expansion are all premised on that interpretation.  You cant use a theory to justify its premises.

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"... the photons instead increase in wavelength and redshift because of a global feature of the spacetime through which they are traveling. One interpretation of this effect is the idea that space itself is expanding."

https://en.wikipedia.org/wiki/Redshift

Wiki even states that space expansion is only ONE interpretation. 

I am guilty of entertaining another interpretation.  Yet despite all your responses you have repeated failed to address the important points; either due to a failure to understand my point, or you are blinded by a desire to be right and steadfast refusal to be helpful.   

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21 minutes ago, AbstractDreamer said:

Yet despite all your responses you have repeated failed to address the important points; either due to a failure to understand my point, or you are blinded by a desire to be right and steadfast refusal to be helpful.   

I feel like you're running around in circles. Altogether the response has been something like 1) There's no reason to either accept or 2) refute your claims because you're not making any testable predictions at all, and 3) you'd need some equations or quantification of effects that make a useful prediction and 4) it would need observational evidence that fits it for it to be treated seriously or accepted, and maybe 5) other stuff I'm forgetting.

You're jumping back and forth attacking individual points without considering them all together. It's like it's a puzzle with many missing pieces and you're asking "why can't we ignore this one piece and work on the rest of the puzzle?" and others are asking to see one piece, any piece, show something, and each time they do, that's the piece you want to ignore next.

This idea is probably perfectly acceptable except that it's missing all the pieces. Missing pieces doesn't mean it's wrong, just that there's nothing there that can be evaluated to see if it's right.

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