# Is there Gravitational Red Shifting?

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#### CliffordK

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##### Is there Gravitational Red Shifting?
« on: 26/04/2012 00:57:02 »
I was just thinking about parallels between light and gravity, both decreasing by the inverse square law.

Gravity, of course, only has one dimension, intensity.

Light could be described with 2 dimensions.
Intensity + (frequency/wavelength/energy),

With (frequency/wavelength/energy) being interdependent, and what we are observing the red-shifting with respect to.

So...
Does gravity have the equivalence of red-shifting with respect to galaxies which are a great distance from us, or receding from Earth?

#### MikeS

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##### Re: Is there Gravitational Red Shifting?
« Reply #1 on: 26/04/2012 07:52:58 »
Stretching space-time results in what we observe as the cosmological red-shift.

quote CliffordK
"So...
Does gravity have the equivalence of red-shifting with respect to galaxies which are a great distance from us, or receding from Earth?"

Yes.
Stretching gravity (space-time) weakens the time dilation factor (time contracts).  We observe this as the cosmological red-shift.
« Last Edit: 26/04/2012 08:05:07 by MikeS »

#### MikeS

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##### Re: Is there Gravitational Red Shifting?
« Reply #2 on: 27/04/2012 09:38:20 »
Sorry Clifford, I seem to have killed the thread.  It's a shame as it's a question of fundamental importance.
« Last Edit: 27/04/2012 10:48:11 by MikeS »

#### CliffordK

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##### Re: Is there Gravitational Red Shifting?
« Reply #3 on: 27/04/2012 12:00:38 »
Thanks,

I try to ignore time in the fabric of space-time.

I suppose the force of gravity is a fraction:

F=$$G\frac{m_1 m_2}{r^2}$$, with units of acceleration of $$\frac{m}{s^2}$$.

Gravitational red-shifting would be an increase in the time factor, and thus a decrease in the acceleration.  However, it would likely be indistinguishable from non red-shifted gravitational acceleration of a lower magnitude.

I suppose it would depend a bit on the speed of gravity which is still being argued about.

#### imatfaal

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##### Re: Is there Gravitational Red Shifting?
« Reply #4 on: 27/04/2012 18:47:56 »
Thanks,

I try to ignore time in the fabric of space-time.

I suppose the force of gravity is a fraction:

F=$$G\frac{m_1 m_2}{r^2}$$, with units of acceleration of $$\frac{m}{s^2}$$.

Gravitational red-shifting would be an increase in the time factor, and thus a decrease in the acceleration.  However, it would likely be indistinguishable from non red-shifted gravitational acceleration of a lower magnitude.

I suppose it would depend a bit on the speed of gravity which is still being argued about.

Just to interject quickly  Force will have the units of Newtons .  You can work out what newtons are in simpler units by thinking of Newtons 2nd law

F=ma   Newtons = kg.m.s-2
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#### MikeS

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##### Re: Is there Gravitational Red Shifting?
« Reply #5 on: 28/04/2012 08:09:10 »
Thanks,

I try to ignore time in the fabric of space-time.

I suppose the force of gravity is a fraction:

F=$$G\frac{m_1 m_2}{r^2}$$, with units of acceleration of $$\frac{m}{s^2}$$.

Gravitational red-shifting would be an increase in the time factor, and thus a decrease in the acceleration.  However, it would likely be indistinguishable from non red-shifted gravitational acceleration of a lower magnitude.

I suppose it would depend a bit on the speed of gravity which is still being argued about.

" Formally, c is a conversion factor for changing the unit of time to the unit of space. This makes it the only speed which does not depend either on the motion of an observer or a source of light and/or gravity. Thus, the speed of "light" is also the speed of gravitational waves and any massless particle."
http://en.wikipedia.org/wiki/Speed_of_gravity

It was measured in 2002
"They found that gravity does move at the same speed as light. Their actual figure was 1.06 times the speed of light, but there was an error of plus or minus 0.21. The results were then announced at the 2002 American Astronomical Society annual meeting in Seattle, Washington.5"
http://www.csa.com/discoveryguides/gravity/overview.php

But your right, it is still being argued over.

#### CliffordK

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##### Re: Is there Gravitational Red Shifting?
« Reply #6 on: 28/04/2012 12:57:06 »
This article suggests that the speed of gravity may in fact be much greater than the speed of light.

http://metaresearch.org/cosmology/speed_of_gravity.asp

#### Æthelwulf

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##### Re: Is there Gravitational Red Shifting?
« Reply #7 on: 28/04/2012 19:15:43 »
This article suggests that the speed of gravity may in fact be much greater than the speed of light.

http://metaresearch.org/cosmology/speed_of_gravity.asp

Yes superluminal theories of gravitation have been around for a while. If spacetime is only a disortion - a curvature without any physical mediator then it may be conceivable that gravity could be a superluminal phenomenon. Personally, I don't think it will, but it is a tantalizing thought since curvature stores energy in the vacuum.

#### MikeS

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##### Re: Is there Gravitational Red Shifting?
« Reply #8 on: 29/04/2012 06:11:29 »
This article suggests that the speed of gravity may in fact be much greater than the speed of light.

http://metaresearch.org/cosmology/speed_of_gravity.asp

Yes superluminal theories of gravitation have been around for a while. If spacetime is only a disortion - a curvature without any physical mediator then it may be conceivable that gravity could be a superluminal phenomenon. Personally, I don't think it will, but it is a tantalizing thought since curvature stores energy in the vacuum.

That's food for thought.  If superluminal then that implies to me that it propagates backward in time.  As the very concept of time is dependent on gravity it seems that gravity could indeed propagate at superluminal speed.

If you think of energy in the form of photons as carrying little arrows of time.  Every arrow points outwards away from the source but they propagate backwards in time at c.

If you apply a similar analogy to gravity.  The arrows all point toward the source of gravity but gravity propagates in the opposite direction.  The arrows are traveling backward in time.  Traveling backward in time is the same as traveling at or faster than c.

If gravity travels at c then it is traveling backwards in time at c (-c + c = 0) or is traveling forward in time at -c.  (c + -c = 0).  It travels backward in time at the same rate that time flows forward.
« Last Edit: 30/04/2012 06:39:34 by MikeS »

#### Æthelwulf

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##### Re: Is there Gravitational Red Shifting?
« Reply #9 on: 29/04/2012 06:15:39 »
This article suggests that the speed of gravity may in fact be much greater than the speed of light.

http://metaresearch.org/cosmology/speed_of_gravity.asp

Yes superluminal theories of gravitation have been around for a while. If spacetime is only a disortion - a curvature without any physical mediator then it may be conceivable that gravity could be a superluminal phenomenon. Personally, I don't think it will, but it is a tantalizing thought since curvature stores energy in the vacuum.

That's food for thought.  If superluminal then that implies to me that it propagates backward in time.  As the very concept of time is dependent on gravity it seems that gravity could indeed propagate at superluminal speed.

Whilst that is technically correct, there are some reinterpretation rules which may escape retrocausal implications, such as veiwing the phenomenon strictly spacelike and not timelike.