Center of the Universe

[MacM]

1100f,

The same holds true with the ballon example. If the movement of the dots become progressively larger then it represents acceleration although you are looking at relative velocities to make that judgement.

ANS: I would be interested to see your explanation of how such dots could attain different velocities (dd/dt) without having da or different accelerations. Different dd/dt and movement of the dots implies acceleration.

Knowing to believe only half of
what you hear is a sign of
intelligence. Knowing which
half to believe will make you a
genius.

 

[1100f]

Originally posted by MacM
1100f,




ANS: I would be interested to see your explanation of how such dots could attain different velocities (dd/dt) without having da or different accelerations. Different dd/dt and movement of the dots implies acceleration.

if two dots on the surfsce of the balloon have different velocities that doesn't mean that there is acceleration.
If the first dot has a velocity v1 that doesn't change (this is what happen when dR/dt is constant, look at equation (*)), then it does not acelerate. If the second dot has a velocity v2 that doesn't change. it has no acceleration, even though v1 and v2 are different.

 

[MacM]

1100f,

if two dots on the surfsce of the balloon have different velocities that doesn't mean that there is acceleration.
If the first dot has a velocity v1 that doesn't change (this is what happen when dR/dt is constant, look at equation (*)), then it does not acelerate. If the second dot has a velocity v2 that doesn't change. it has no acceleration, even though v1 and v2 are different.

ANS: I fail to follow your logic. Yes we see a velocity of an object having v1 velocity. Then we see another object farther away with v2 velocity, Then #3 and v3, #4 and v4.

Each object progressively farther away has higher and higher velocity. That is what they see and from that they conclude the expansion is accelerating.

Do you agree?

Knowing to believe only half of
what you hear is a sign of
intelligence. Knowing which
half to believe will make you a
genius.

 

[1100f]

Originally posted by MacM
1100f,

ANS: I fail to follow your logic. Yes we see a velocity of an object having v1 velocity. Then we see another object farther away with v2 velocity, Then #3 and v3, #4 and v4.

If dR/dt is constant, each object has all the time the same velocity.
An object at distance L will have a velocity v, after some time δt it will have a velocity v and it will be at a distance L + vδt, after anither time vδt, it will have a velocity v and it will be located at a distance L + 2vδt. It is not accelerating.
Next take another object that is located at a distance 2L. It will have a velocity 2v (according to Hubble law). After a time vδt, it will have a velocity 2v and it will be located at a distance 2(L+vδt). After another time vδt, it will have a velocity 2v and will be located at a distance 2(L+2vδt). It is not accelerating.
At each moment, Hubble law holds, but there is no acceleration.

Originally posted by MacM
Each object progressively farther away has higher and higher velocity. That is what they see and from that they conclude the expansion is accelerating.

Do you agree?

I don't agree since I have just shown that Each object progressively farther away has the same velocity.

 

[MacM]

1100f,

I don't agree since I have just shown that Each object progressively farther away has the same velocity.

ANS: The only problem I see here is that you are assuming your example represents observation and it does not.

Observation has velocities increase with distance and that represents acceleration.

Knowing to believe only half of
what you hear is a sign of
intelligence. Knowing which
half to believe will make you a
genius.

 

[1100f]

Originally posted by MacM
1100f,




ANS: The only problem I see here is that you are assuming your example represents observation and it does not.

Observation has velocities increase with distance and that represents acceleration.

If at a distance L you have a velocity v and at a distance 2L you have a velocity 2v than I was thinking to that the two velocities are not the same, and that the velocity increases with distance.

 

[MacM]

1100f,

If at a distance L you have a velocity v and at a distance 2L you have a velocity 2v than I was thinking to that the two velocities are not the same, and that the velocity increases with distance.

ANS: This sounds correct in general. I'm not sure the acceleration is linear but your description is of acceleration.



Knowing to believe only half of
what you hear is a sign of
intelligence. Knowing which
half to believe will make you a
genius.

 

[1100f]

Originally posted by MacM
1100f,




ANS: This sounds correct in general. I'm not sure the acceleration is linear but your description is of acceleration.

If the velocity of the first dot is constant (equal to v all the time), it does not accelerate.

The velocity of the second dot is all the time 2v, it does not change, how can you say that there is an acceleration?

 

[MacM]

1100f,

If the velocity of the first dot is constant (equal to v all the time), it does not accelerate.

The velocity of the second dot is all the time 2v, it does not change, how can you say that there is an acceleration?

ANS: I believe the assumption upon which the accelerating expansion is claimed is that the sequence you described implies acceleration.

That is look back in a few centuries and when object 1 has reached the distance of where object 2 is now, you will find object 1 will have increased its velocity comperable to what object 2's velocity is now and object 2 will be further away and have a velociy of v=3.

Knowing to believe only half of
what you hear is a sign of
intelligence. Knowing which
half to believe will make you a
genius.

 

[1100f]

Originally posted by MacM
1100f,






ANS: I believe the assumption upon which the accelerating expansion is claimed is that the sequence you described implies acceleration.

That is look back in a few centuries and when object 1 has reached the distance of where object 2 is now, you will find object 1 will have increased its velocity comperable to what object 2's velocity is now and object 2 will be further away and have a velociy of v=3.

The sequence that I described did not imply any acceleration.
Look at the relation between the Hubble parameter and radius of the balloon:
H = (dR/dt)/R. If dR/dt is constant, then R is not a constant. So the Hubble parameter get smaller and smaller.

If you have an object at distance L with velocity v and another object at distance 2L with velocity 2v, after some time the first object will be at distance 2L with velocity v and the second object will be at distance 4L with velocity 2v. The Hubble parameter is now half the value it had when the first object was at distance L.

The first object had a velocity v, it has now a velocity v
Question: What is its acceleration?

 

[MacM]

1100f,

Question: What is its acceleration?

ANS:Acceleration is a change in velocity over time. That is what they think they see in the universe. The farther you look out into the universe the farther back in time you are looking and the faster the objects are receeding.

It is increased velocity over time - acceleration.

Knowing to believe only half of
what you hear is a sign of
intelligence. Knowing which
half to believe will make you a
genius.

 

[1100f]

Originally posted by MacM
1100f,





It is increased velocity over time - acceleration.

And it is not increased velocity over distance.

Finnally we agree. If a particle has the same velocity over time, it doesn't have acceleration.

If a particle has a velocity v all the time, it does not accelerate.

If the rate dR/dt is constant, we have found that the velocity of this particle located at some time at a distance L does not change .So it does not have acceleration

 

[MacM]

1100f,

And it is not increased velocity over distance.

Finnally we agree. If a particle has the same velocity over time, it doesn't have acceleration.

If a particle has a velocity v all the time, it does not accelerate.

If the rate dR/dt is constant, we have found that the velocity of this particle located at some time at a distance L does not change .So it does not have acceleration

ANS: I am really at a loss as to what you are trying to say.

1 - We see objects having higher and higher velocity in direct relation to distance from us.

2 - We interprete that to mean they are accelerating away not merely moving away at a fixed velocity.

3 - Obviously if an object HAS constant velocity over time it is not accelerating; however, that is not what we see in the universe.

You seem to be mixing true statements in with statements about observations of the universe which produce false statements about the accelerating expansion of the universe.

Knowing to believe only half of
what you hear is a sign of
intelligence. Knowing which
half to believe will make you a
genius.

 

[AndersHermansson]

If we look back 15 billion years and the objects are receeding very fast aren't we looking at how fast it was receeding 15 billion years ago?