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setting the Minkowski Spacetime model in motion


tar
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On 12/4/2021 at 9:36 AM, swansont said:

Claiming this means you reject relativity, because there are no absolute frames in relativity, and relativity allows you to compare the observation of different frames.

You would need to provide evidence of this absolute frame.

Which has nothing to do with being “in reference to the universe”

It’s just your motion relative to the source 

 

Repeating this doesn’t make it true. Why can’t you provide experimental evidence to support you claims?

What does this mean?

I choose to consider that there is an absolute frame and that is the frame in which in which light travels.

often in experiments there is a choice as to what you hold constant and compare everything against

a photon does not know it is in an experiment.  It just goes out from the source

when an electron falls from one quantum level to another the fall creates a particle or a wave or some combination but an impulse that travels out across the fabric of space til it hits an electron in an atom somewhere and gives up its quantum of energy to the electron which then exists in a higher energy state

you can't tell a lot from the energy that one photon hits with, you need a bunch to make a case 

a bunch can only be available if many sources are considered and they are created over time

such is a problem when doing experiments or using data from distant stars where you get one photon an hour from the source and you don't know how the source changed in that hour

but, I think there is experimental evidence that there is a reference frame that stays constant, because we measure the blue shift and red shift of hydrogen lines that tell us we are moving toward or away, relatively from the source

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11 minutes ago, tar said:

I choose to consider that there is an absolute frame and that is the frame in which in which light travels.

You don't get to do this in a discussion of relativity.

You have to establish this as true before you can do anything else, if you are arguing from some other model to work.

11 minutes ago, tar said:

often in experiments there is a choice as to what you hold constant and compare everything against

You are claiming there is no choice in terms of a reference frame. An absolute frame requires you can measure your motion with respect to it. How do you tell if you are the one that's moving?

It depends on the experiment. 

11 minutes ago, tar said:

but, I think there is experimental evidence that there is a reference frame that stays constant, because we measure the blue shift and red shift of hydrogen lines that tell us we are moving toward or away, relatively from the source

They are from relative motion, as you admit, so how are they evidence of an absolute frame?

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I have read that many times over the years, and always have not agreed on what was proven or disproven

We are back to the river question.

Is the distance traveled by the photons along the river bottom, or through the ether.

 I submit that the mirrors at the end of the experiment were in different locations all during the experiment and at the beginning.

The Earth is moving, the Sun is moving, the Galaxy is moving.

Any one photon does not know it is in an experiment.

Question for you.  When a photon hits a mirror, is it the same photon that bounces off, or is the original photon absorbed and an identical  quantum of energy released?

15 minutes ago, swansont said:

You don't get to do this in a discussion of relativity.

You have to establish this as true before you can do anything else, if you are arguing from some other model to work.

You are claiming there is no choice in terms of a reference frame. An absolute frame requires you can measure your motion with respect to it. How do you tell if you are the one that's moving?

It depends on the experiment. 

They are from relative motion, as you admit, so how are they evidence of an absolute frame?

So why not consider the Earth as a preferred frame?  Then measure what is moving relative to it and what it is moving relative to?

5 minutes ago, tar said:

I have read that many times over the years, and always have not agreed on what was proven or disproven

We are back to the river question.

Is the distance traveled by the photons along the river bottom, or through the ether.

 I submit that the mirrors at the end of the experiment were in different locations all during the experiment and at the beginning.

The Earth is moving, the Sun is moving, the Galaxy is moving.

Any one phot on does not know it is in an experiment.

Question for you.  When a photon hits a mirror, is it the same photon that bounces off, or is the original photon absorbed and an identical  quantum of energy released?

So why not consider the Earth as a preferred frame?  Then measure what is moving relative to it and what it is moving relative to?

Relativity is, in my opinion understood completely when you notice that your location is unique and all other locations are a distance from you, and light takes time to travel that distance,  And all other locations exist in a particular orientation to everything else, only once in the same way that your present happens only once.

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On 12/4/2021 at 2:07 PM, tar said:

I think I am not clear on what is standing for what in the river analogy.

One of the confusions in my understanding of relativity is when distance is used in a spacelike way and when it is used in a time like way. 

My solution is to consider…

My entry screen is confounded.  Even in word.

 

I'm sure it could be very helpful to you to complete this post as I am waiting for you to tell me what you are confused about with Bondi's book.

Sorting this out could be much more productive than challenging swansont.

 

Edit

I see you have referred several times to 'the river analogy'  since you first mentioned the pages in Bondi's book.

You did not confirm that I found the correct ones, please do so or refer to the correct ones as the case may be.

Please also note that the scanned pages I posted are not an analogy and they are not Einstinian Physics either.

They are just plain and simple old Newtonian Physics.

 

Edited by studiot
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1 hour ago, tar said:

I have read that many times over the years, and always have not agreed on what was proven or disproven

Feel free to discuss that in another thread

1 hour ago, tar said:

We are back to the river question.

Is the distance traveled by the photons along the river bottom, or through the ether.

It's from point A to point B. Where the photon started to where it ends up. 

1 hour ago, tar said:

 I submit that the mirrors at the end of the experiment were in different locations all during the experiment and at the beginning.

It doesn't matter. If both of them move the same amount, the interval remains the same. It's only motion relative to each other that would change anything.

1 hour ago, tar said:

The Earth is moving, the Sun is moving, the Galaxy is moving.

And none of that matters, as these motions are, to a very good approximation, inertial.

1 hour ago, tar said:

Any one photon does not know it is in an experiment.

Question for you.  When a photon hits a mirror, is it the same photon that bounces off, or is the original photon absorbed and an identical  quantum of energy released?

No way to tell. There's a good argument that it's a different photon, because a photon ceases to exist when it's absorbed.

Why does this matter?

1 hour ago, tar said:

So why not consider the Earth as a preferred frame?  Then measure what is moving relative to it and what it is moving relative to?

Because it's not.

You can choose to use it for convenience, but there isn't any physics that tells you the earth is at rest (considering only inertial motion) and all other objects are moving.

1 hour ago, tar said:

Relativity is, in my opinion understood completely when you notice that your location is unique and all other locations are a distance from you, and light takes time to travel that distance,  And all other locations exist in a particular orientation to everything else, only once in the same way that your present happens only once.

Your stance isn't even consistent. You acknowledge that the earth is moving, so how can its location be unique?

And, to ask yet again, what experiment would show that the earth is at absolute rest?

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1 hour ago, tar said:

Question for you.  When a photon hits a mirror, is it the same photon that bounces off, or is the original photon absorbed and an identical  quantum of energy released?

There is no such thing as this or that photon. Photons have no identity, so your question is meaningless.

As are the questions,

Where was the photon before the electron emitted it?

Where is the photon after it's been absorbed?

Etc.

x-posted with Swansont.

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1 minute ago, joigus said:

There is no such thing as this or that photon. Photons have no identity, so your question is meaningless.

As are the questions,

Where was the photon before the electron emitted it?

Where is the photon after it's been absorbed?

Etc.

x-posted with Swansont.

This is a more succinct way of presenting it. You can argue whether it's the same photon but ultimately it becomes this set of questions, which are more philosophy (or zen koan) than physics.

The physics part is that photons are bosons, so you can create as many as you want, and destroy them all, as long as you follow the other rules (i.e. conservation laws)

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I think talking (arguing) about photons is pointless in Relativity.

Photons are only part of light's story anyway.

Einstein in his original paper went to great lengths to avoid (do without) the actual mechanism of light and its propagation.
He was well aware of the difficulties about the nature of light faced by physicists of that time.

His derivation would still hold good if light were actually found to be something else entirely.

These days we tend to shorcut this because we know much more about the nature of light.

But focusing on light is not the way to Relativity IMHO.  (pun intended)

Edited by studiot
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Photons weren't a part of physics back then anyway; Einstein had only submitted the photoelectric effect paper a few months prior to his SR paper, and the quantum nature of light didn't become mainstream physics until a bit later.

Nothing in SR is dependent on light having a quantum nature.

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15 minutes ago, swansont said:

Photons weren't a part of physics back then anyway; Einstein had only submitted the photoelectric effect paper a few months prior to his SR paper, and the quantum nature of light didn't become mainstream physics until a bit later.

Nothing in SR is dependent on light having a quantum nature.

Yes I'm aware of that, but Einstein was still pretty general.

He used 'pulses' or flashes of light not continuous waves.

That could just as easily have been pulses of 'superfast lentil pudding', for all the bearing it had on his argument. (pun intended).

It was the pulses that were important.

And, of course, I think you deal with pulses of  laser light today?

No offence to tar but I think he is trying to run before he can walk.
Bondi's  (excellent) book is aimed at folks in his situation.
But it still requires careful reading as with any serious subject.

Here is the preface explaining his approach, if you haven't seen it.

Bondi2.jpg.0ffdd9815d4255b73c26c2b571c39f7c.jpg

Edited by studiot
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3 hours ago, swansont said:

This is a more succinct way of presenting it. You can argue whether it's the same photon but ultimately it becomes this set of questions, which are more philosophy (or zen koan) than physics.

The physics part is that photons are bosons, so you can create as many as you want, and destroy them all, as long as you follow the other rules (i.e. conservation laws)

One language snippet that I've developed to try to explain this admittedly hard-to-understand concept is that quantum fields are instantiation devices. The analogy cannot be taken too far though, because, eg, instances of a program have and ID, while quanta haven't. You can insist on tagging them, but it's the wrong way to proceed...

Perhaps there is no better way than getting your hands dirty with the maths, even at an elementary level, trying to express the field operators in the Fock representation: particle number 1, number 2, etc. Pretty soon the whole thing becomes a mess. Then you change the variables to the number representation: this many particles with state such and such. The way in which the equations get simpler hits you like a ton of bricks.

Edited by joigus
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