Is an exapnding universe a violation of the principle of relativity?

[Qfwfq]

If one believes in a expanding universe that is also isotropic,

Isotropic according to comoving coordinate choices.

 

If we were moving at a sufficiently higher velocity than the current one from this position, we should not get such isotropy

It isn't a violation of the principle of relativity. The laws of dynamics are the same for such a choice of coordinates.

[quantumtopology]

Isotropic according to comoving coordinate choices.

 

It isn't a violation of the principle of relativity. The laws of dynamics are the same for such a choice of coordinates.

 

Thanks Qf, that had been completely clarified and understood some posts ago.

 

Hey did you read my question about your signature? I'm curious about what languae is writen in.

 

Regards

QTop

[Qfwfq]

It's the vernacular of the area around Conegliano Veneto. A past colleague had it on the wall above his desk; apparently he didn't like folks trying to teach him things he wasn't interested in learning. It means: No use teaching an ***, it's a waste of time and what's more it irritates the beast.

[HydrogenBond]

One of the problems with relative reference is, it can be used to violate the conservation of energy to create special effects. Here is a simple example. We have three stationary references; A, B,C. While all the observers are asleep, we will add propulsion energy to one of the references (:P to give it a velocity.

 

Next, we ask each of the references who is moving. Reference A can't tell for sure, but it will see one moving and one stationary reference. Reference B is also not sure, but it will see both references moving or both references stationary. While reference C, who is also not sure, will also see one moving and one stationary.

 

Although reference A and C, will complete the energy balance, reference B will either be high or low by 50%. If we assume relative reference and politic to make B the one we want (it is all relative) we could theoretically add another 50% more energy. With that extra energy we can create special effects.

 

The only way to make sure all references satisfy the original energy balance (tell all how much energy was added) at the same time, will be to say A and C have to be stationary references and B has to be the moving reference. The energy balance only works with an absolute scale.

[modest]

...violate the conservation of energy... we will add propulsion energy to one of the references (:P to give it a velocity.

 

This is not a violation of the conservation of energy. The center of mass of B and its propellant does not move.

 

Kinetic energy is relative, which is to say that the total kinetic energy of a system depends on the frame of reference from which it is viewed. The kinetic energy of the system in the center of momentum frame is the invariant (it adds to the invariant mass). The invariant mass is agreed upon by all observers regardless of frame and it is conserved which is to say that it cannot change value in an isolated system no matter what happens inside the system.

 

~modest

[HydrogenBond]

I did not say the propulsion violated the conservation of energy. I said that when all three references (2 stationary and 1 in motion) look at each other (they don't know who got the propulsion) there is only one way to order the references so every reference comes up with the same/actual energy balance.

[modest]

I did not say the propulsion violated the conservation of energy. I said that when all three references (2 stationary and 1 in motion) look at each other (they don't know who got the propulsion) there is only one way to order the references so every reference comes up with the same/actual energy balance.

 

The principle of relativity does not require each observer to agree on the energy of a system. They need to agree on the invariant mass. It you consider the propellant as part of your thought experiment then all observers will agree on the invariant quantity both before and after the ship is accelerated.

 

~modest

[LaurieAG]

Hi Qfwfq, guys,

 

It's the vernacular of the area around Conegliano Veneto. A past colleague had it on the wall above his desk; apparently he didn't like folks trying to teach him things he wasn't interested in learning. It means: No use teaching an ***, it's a waste of time and what's more it irritates the beast.

 

That wouldn't go over too well where I work as we've just started a process that will end in a large scale ERP rollout. From a HR perspective its much more productive to realise that you can easily teach an ignorant person who is honest but it is difficult to teach a person who is ignorant and dishonest because it is difficult to verify if they ever learnt anything.

 

My own signature has reflected this position for quite a while now.

 

modest said earlier that

But, the objection 'things should be relative and this doesn't seem to be' is philosophical. It wouldn't be surprising if the rebuttal is equally philosophical.

 

To put this position in the philosophical context of what is exactly a violation of what is to honestly answer how you can justify regarding models generated from the reverse engineering of selective data as being exactly equivalent to a successful hypothesis validation obtained through the scientific method being applied to a process that actually flows in the opposite direction without performing repeatable independent external verification.

 

Put simply is obedience comparable to verified competency?

[quantumtopology]

To put this position in the philosophical context of what is exactly a violation of what is to honestly answer how you can justify regarding models generated from the reverse engineering of selective data as being exactly equivalent to a successful hypothesis validation obtained through the scientific method being applied to a process that actually flows in the opposite direction without performing repeatable independent external verification.

 

Put simply is obedience comparable to verified competency?

 

Well put. (though I must admit I had to read this paragraph several times to get it.);) Obviously my answer is negative ,but I think the question was actually rhetorical.

 

Regards

Qtop

[HydrogenBond]

It has been demonstrated that the universe is composed of superstructure. These are large scale organization within the universe. Based on the size, scale and gravity considerations, these would have needed to been part of the original formation of the universe. The main point I am making is the universe has never been isotropic.

 

If we wanted to go from super structure to an isotropic expansion, this could be done by adding energy to spread out the structure. Using relative reference, we can create the extra energy needed to allow the assumption of an isotropic expansion.

 

This is why we need an absolute reference scale; prevents assumptions which are based on an energy imbalance.

[modest]

To put this position in the philosophical context of what is exactly a violation of what is to honestly answer how you can justify regarding models generated from the reverse engineering of selective data as being exactly equivalent to a successful hypothesis validation obtained through the scientific method being applied to a process that actually flows in the opposite direction without performing repeatable independent external verification.

 

That's quite a long sentence there. Ironically, I think it's an incomplete sentence at that.

 

I don't know, Laurie. I think you're saying that something is ad hoc. I think you're asking me how I can justify a "model" being ad hoc. Which model exactly are you talking about, and what is the relation to the thread's title?

 

~modest

[LaurieAG]

hi modest, QTop,

 

That's quite a long sentence there. Ironically, I think it's an incomplete sentence at that.

 

I should have added that the independent verification should not be reverse engineered but the sentence was getting long enough as it was.

 

Which model exactly are you talking about, and what is the relation to the thread's title?

 

I would have thought that was obvious, 'Is an expanding universe a violation of the principle of relativity?', as there's an extremely high probability that this statement can be proven true if the universe can be proved not to be expanding.

[modest]

I would have thought that was obvious, 'Is an expanding universe a violation of the principle of relativity?', as there's an extremely high probability that this statement can be proven true if the universe can be proved not to be expanding.

 

An expanding universe either violates the principle or not. It is a matter of logic. The thread's title is true or false regardless of what our universe is doing.

 

It is not, as I think we've established, a violation.

 

~modest

[Qfwfq]

To put this position in the philosophical context of what is exactly a violation of what is to honestly answer how you can justify regarding models generated from the reverse engineering of selective data as being exactly equivalent to a successful hypothesis validation obtained through the scientific method being applied to a process that actually flows in the opposite direction without performing repeatable independent external verification.

 

Put simply is obedience comparable to verified competency?

OMG can somebody pass me the bong? Quick, I'm needing a gooooood looooong puff.

[maddog]

Modest -- explain to me the violation we have ?

 

An expanding universe does Not violate Principle of Relativity (SR or GR). So where is

the paradox ?

 

Any transformation of one coordinate system to another by use of equations of motion

can account for all variances. As others have already said here. All observers do not

necessarily observe the same motion of objects since the may be in motion with respect

to each other.

 

maddog

[modest]

Modest -- explain to me the violation we have ?

 

You might ask Quantumtopology. It was his question—split from another thread.

 

An expanding universe does Not violate Principle of Relativity (SR or GR). So where is

the paradox ?

 

I agree. You might read posts 1, 6, 18, and 19.

 

Any transformation of one coordinate system to another by use of equations of motion can account for all variances. As others have already said here.

 

Yeah, I'm one of those 'others'. B)

 

~modest

[LaurieAG]

Hi qfwfq,

 

OMG can somebody pass me the bong? Quick, I'm needing a gooooood looooong puff.

 

If thats what you need to look at things from a different perspective?

 

There's an article in Scientific American 'Is the universe leaking energy' by T.M. Davis that has other perspectives using general relativity and relative velocities.

 

...

Second, one must compare the velocity of the galaxy at the time when it emitted the photon with the velocity of the observer at the time when the photon was received and then - using the appropriate math derived from general relativity - calculate the relative velocity. The doppler shift calculated from this relative velocity coincides with the galaxies redshift, suggesting that the galaxies redshift can be interpreted as the result of relative motion, rather than of the expansion of space. Therefore no energy is lost.

 

Last week I read an article on the difference between serial and parallel PC hard drive connector cables and noticed that the key definition of the 'frame' is different depending on the communication method being used.

 

Considering that any individual photon has a discrete, but not necessarily straight path from its source to an observation point along this path then surely the relevant observation frame is that of the discrete observation point during that discrete time period.