[charles1948]

Why this continual resort to individual "reference-frames"?

What have they got to do with physical reality?

I mean, suppose you fell out of an aircraft flying at 20,000 feet..

During the time you were falling, you might think " Hey this great!  I'm in my own individual reference-frame!  Just me! No more aircraft!  I'm independent of it!  I can move my legs and arms about freely, without even feeling any gravity!  There's only air, seeming to rush past, but I can cope with that!

Hang on though - what's this underneath me approaching fast - it must be the ground.  Well sucks to the ground and its reference frame - I'm in my own individual reference fra.........

[Kryptid]

Why this continual resort to individual "reference-frames"?

Because that's how relativity works.

What have they got to do with physical reality?

Everything. Times and distances are different for observers in different reference frames.

I mean, suppose you fell out of an aircraft flying at 20,000 feet..

During the time you were falling, you might think " Hey this great!  I'm in my own individual reference-frame!  Just me! No more aircraft!  I'm independent of it!  I can move my legs and arms about freely, without even feeling any gravity!  There's only air, seeming to rush past, but I can cope with that!

Hang on though - what's this underneath me approaching fast - it must be the ground.  Well sucks to the ground and its reference frame - I'm in my own individual reference fra.........

What do you think this is supposed to prove?

[MikeFontenot (OP)]

Thanks Mike. When you refer to "negative ageing" do you mean that the CMIF method makes people get younger?

In the CMIF method, if the observer (he) suddenly accelerates in the direction TOWARD the distant person (her), he will conclude that she suddenly gets much older. (That is what the CMIF method says happens during the turnaround in the famous 'twin paradox".)   If instead, he suddenly accelerates in the direction AWAY from her, he will conclude that she suddenly gets much younger.  In either case, she won't agree that his velocity changes have had ANY effect on her current age.  And other observers who aren't accelerating won't think her current age is making any sudden changes.

[charles1948]

Why this continual resort to individual "reference-frames"?

Because that's how relativity works.

What have they got to do with physical reality?

Everything. Times and distances are different for observers in different reference frames.

I mean, suppose you fell out of an aircraft flying at 20,000 feet..

During the time you were falling, you might think " Hey this great!  I'm in my own individual reference-frame!  Just me! No more aircraft!  I'm independent of it!  I can move my legs and arms about freely, without even feeling any gravity!  There's only air, seeming to rush past, but I can cope with that!

Hang on though - what's this underneath me approaching fast - it must be the ground.  Well sucks to the ground and its reference frame - I'm in my own individual reference fra.........

What do you think this is supposed to prove?

Perhaps nothing, except that modern physics is losing touch with reality.  Becoming  more like an intellectual exercise with no physical verification of its speculations.

I mean, do you really and truly believe that the Higg's Boson and Gravitational Waves have been proved to exist?

[Kryptid]

Perhaps nothing, except that modern physics is losing touch with reality.

You're going to need to explain why someone falling towards to ground is supposed to illustrate that.

I mean, do you really and truly believe that the Higg's Boson and Gravitational Waves have been proved to exist?

No, because there is no such thing as proof in science. There is very good evidence for them, however.

[charles1948]

Perhaps nothing, except that modern physics is losing touch with reality.

You're going to need to explain why someone falling towards to ground is supposed to illustrate that.

I mean, do you really and truly believe that the Higg's Boson and Gravitational Waves have been proved to exist?

No, because there is no such thing as proof in science. There is very good evidence for them, however.

The trouble is that  the "evidence" for supposed particles like the Higgs Boson, and Gravitational Waves, seems to rely on statistical analysis of "meter readings" and extrapolations from graphical charts.

This is very different from the old days when particle physics employed Bubble Chambers, in which the ionised tracks left by particles could be actually seen and photographed.

These days there are no photographs.

[Bored chemist]

These days there are no photographs.

The other day, you were complaining that we are still talking about wind power. Today you are complaining that we no longer use old methods.

When you have finished arguing with yourself, let us know who won.

In the mean time, you might want to consider that the half life of the Higgs Boson is about  10^-21 of a second.
Travelling at roughly the speed of light, it would cover a ten billionth of a millimetre or about 1/100 of the diameter of a hydrogen atom before it fell apart.

How, exactly, would you propose to get a picture of that?

[Bored chemist]

The trouble is that  the "evidence" for supposed particles like the Higgs Boson, and Gravitational Waves, seems to rely on statistical analysis of "meter readings" and extrapolations from graphical charts.

In what way is this "trouble"?
Do you not understand it?

[charles1948]

These days there are no photographs.

The other day, you were complaining that we are still talking about wind power. Today you are complaining that we no longer use old methods.

When you have finished arguing with yourself, let us know who won.

In the mean time, you might want to consider that the half life of the Higgs Boson is about  10^-21 of a second.
Travelling at roughly the speed of light, it would cover a ten billionth of a millimetre or about 1/100 of the diameter of a hydrogen atom before it fell apart.

How, exactly, would you propose to get a picture of that?

If I was told that a supposed "particle" couldn't exist long enough to travel across 1/100th the diameter of a hydrogen atom before it fell apart,  I would strongly suspect that the "particle" didn't actually exist in the first place.

So I wouldn't waste time trying to take a picture of it.

[Kryptid]

The trouble is that  the "evidence" for supposed particles like the Higgs Boson, and Gravitational Waves, seems to rely on statistical analysis of "meter readings" and extrapolations from graphical charts.

Maybe next time you get your electric bill, you can send them some mail claiming that they can't conclude that you used any electricity because they are relying on "meter readings". Do you think that will work?

This is very different from the old days when particle physics employed Bubble Chambers, in which the ionised tracks left by particles could be actually seen and photographed.

These days there are no photographs.

So you think no photographs equals no evidence? Right. We might as well let everyone out of prison who wasn't filmed committing the crime...

If I was told that a supposed "particle" couldn't exist long enough to travel across 1/100th the diameter of a hydrogen atom before it fell apart,  I would strongly suspect that the "particle" didn't actually exist in the first place.

So I wouldn't waste time trying to take a picture of it.

Good for you. Actual scientists, on the other hand, would know how to infer its existence from the particles it leaves behind.

[charles1948]

Your remark reminds me of something from the " Hitchhiker's Guide to the Galaxy" series of books!

In one of the books, scientists had a small piece of "fairy-cake", whatever that is, subjected to intense scientific examination.  With probes inserted into the cake.  The readings from the probes, enabled the composition, structure and functioning of the entire Universe to be inferred and deduced.

Is that possible, do you think?

[Kryptid]

Is that possible, do you think?

Probably not, but I'd never rule anything out for sure.

[Colin2B]

So I wouldn't waste time trying to take a picture of it.

How about you stop wasting our time by posting your nonsense in the main part of the forum.
Feel free to post your ‘theories’ in the appropriate section rather than here, otherwise you might find your ability to post in the main sections limited.

If it were left to you Hertz would have been told to ignore the meter reading and forget that radio waves might be discovered.

[charles1948]

 Suppose  Marconi had been told, as he probably was, that meter-readings of radio-waves conclusively proved that the waves always travel in straight lines.

Therefore radio-waves couldn't possibly travel across the Atlantic from Europe to America. It's nonsense! Owing to the obvious upward obstruction between the two continents caused by the curvature of the Earth. 

But... .Heaviside layer and all that ........you know the rest

[gem]

Hi all
now I know there has been a lot of activity and there is certain links I will try to find the time to study, but can we rewind a little So Halc yes I take your point

'Come to rest' is dang undefined without frame reference. If the ship is constantly accelerating, then it is gaining speed and not coming to rest.  It can cease accelerating and therefore be at rest in its own frame, but the clocks will be very out of sync after that.

So I will try to set a scenario that is CMIF and is in touch with reality that we all can relate to.
we have a space ship that is stationary in space, away from any gravitational influence, on this ship is two synchronized atomic clocks with two observers.
The distance between the clocks is 19.62 m  the ship accelerates at 9.81 ms^-2 for 2 seconds then decelerates at 9.81 ms^-2 for 2 seconds back to zero

So my back of a fag packet calcs are the observer at the back of the ship will see the clock at the front being 1.07 x 10^-15 sec ahead/faster than his at the 2 sec point and being synchronized again at the four second point.
The question that brings to my mind is what are the clocks actual rate ?

I believe it would be reasonable but happy to be corrected, that for the 2 seconds that they both accelerate they would both slow down by the rate we measure time dilation to be here on earth ( aprox 6.95 x 10^-10 sec/sec)  and they would both speed up by the same margin for the 2 sec they decelerate,
hence they are actually synchronized throughout in reality due to their inertial reference frame to each other.   

[Halc]

My apologies for the derailment of your topic by others. I will move them into a new topic if requested.

I HAVE chosen a coordinate system.

Great! Then events are perhaps ordered according to that choice of coordinate system, and not according to the chooser of it.

The coordinate system I chose defines the spatial origin to be where the observer who sometimes accelerates is.  The purpose of the coordinate system is to allow that observer to determine the spatial position and the current age of any distant person of interest.

For there to be a current age of anybody, there needs to be a current time on the preferred worldline (time 0 presumably). Are you asserting a preferred time as well?

But the problem of interest to me is that the concept of simultaneity inherent in that definition is not universally agreed upon

The one you chose cannot be agreed upon since
1) the universe would need to know the exact path of the worldline upon which the coordinate system is based (which is very difficult if it is always located at location 0, and
2) it is not a true simultaneity method (at least the CMIF one isn’t) because multiple events at the preferred worldline are simultaneous with events sufficiently distant from that worldline. There’s a many-to-one mapping, so nobody not on the worldline can know what time it is according to the method. Somebody could say when your birthdays are even if they don’t occur in order, but they could not say when their own birthdays are.
Such a method is only a one-way simultaneity method, not a coordinate system.  Relative to any event at location zero, there is a list of events simultaneous with that event, but it only works one way, so there is no distinct coordinate of events not at spatical location 0.

If the more complicated method avoids this multiple-mapping problem and gives a unique coordinate to every event (not even inertial frames do this in reality, only in Minkowski spacetime which doesn’t correspond to anything real), then the method avoids this one problem, qualifies as a coordinate system, but still has to deal with the first issue.

The most widely used simultaneity method (by far) is CMIF (co-moving inertial frames) simultaneity.

Actually I cannot think of anybody using it in a practical situtation. It’s perhaps used as a teaching aid in class, but not in real situtaions.

The well-known physicist Brian Greene is not so disturbed, and gives the most startling example of negative ageing

The Andromeda ‘paradox’ has been around a long time and I doubt this guy broke that ground.

When you refer to "negative ageing" do you mean that the CMIF method makes people get younger.

A coordinate system that assigns later times to somebody young than to the same person old is just assigning different numbers to a line. It is just an abstract coordinate system and such abstractions have no causal effect on actual events, so no, it doesn’t make anything actually get younger.

[Kryptid]

Suppose  Marconi had been told, as he probably was, that meter-readings of radio-waves conclusively proved that the waves always travel in straight lines.

Just another reason why you should never use the word "proved" when it comes to science.

[Colin2B]

Suppose  Marconi had been told, as he probably was, that meter-readings of radio-waves conclusively proved that the waves always travel in straight lines.

I’m quite sure someone did tell him this, but experiment proved otherwise.
However, this is still posting your alternative theory in a post on a different subject, in the main section.
Please take note of my warning, the choice is yours.

[MikeFontenot (OP)]

The coordinate system I chose defines the spatial origin to be where the observer who sometimes accelerates is.  The purpose of the coordinate system is to allow that observer to determine the spatial position and the current age of any distant person of interest.

For there to be a current age of anybody, there needs to be a current time on the preferred worldline (time 0 presumably). Are you asserting a preferred time as well?

I'll elaborate a little.

My coordinate system's horizontal axis gives each instant in the life of the observer (he) who sometimes accelerates (or at least the portion of his life we are interested in, like the portion that includes his trip away from the home twin).  The vertical axis gives the home twin's (her) age, as a function of his age, according to him.  I call this diagram "the age correspondence diagram" (ACD).  It gives the complete simultaneity-at-a-distance information that he wants about her.

There are (at least) four such diagrams: the one for CMIF simultaneity, the one for the Dolby and Gull Simultaneity, the one for Minguizzi simultaneity, and the one for my newly discovered simultaneity ... I call it "Fontenot's simultaneity".  CMIF simultaneity is by far the best known, but it is disliked by some people because it's ACD can have discontinuities ... specifically, her age can instantaneously increase or instantaneously decrease.  The other three simultaneity methods have no discontinuities, and no negative ageing.

I actually prefer the CMIF method.  The discontinuities and negative ageing don't bother me at all.  And they clearly don't bother Brian Greene, either.

It's possible to produce a similar diagram that gives the home twin's distance from the traveler, according to the traveler, at each instant of the traveler's life.  It also has discontinuities in the CMIF method.  I don't find such a diagram to be very useful or important.  I prefer to just keep track of the separation of the twins according to the home twin.  I just use a Minkowski diagram, which plots on the vertical axis the position of the traveler according to the home twin, versus the home twin's age on the horizontal axis.  That diagram is the basic starting point for all four of the simultaneity methods.

[Halc]

I'll elaborate a little.

My coordinate system's horizontal axis gives each instant in the life of the observer (he) who sometimes accelerates (or at least the portion of his life we are interested in, like the portion that includes his trip away from the home twin).  The vertical axis gives the home twin's (her) age, as a function of his age, according to him.

It isn’t a coordinate system if it doesn’t assign 4 coordinates to every event in the region-of-applicability. I don’t know about you latest proposed method, but CMIF certainly does not qualify as a coordinate system for the reasons above. Ditto with Minguizzi who only assigns coordinates to one other worldline (that of the twin) and only if that twin remains stationary the whole time. Coordinates of other events are not defined.

The other three simultaneity methods have no discontinuities, and no negative ageing.

OK, so maybe one of them qualifies as a choice of coordinate systems. I’m unfamiliar with the others.

I actually prefer the CMIF method.

That’s a perfectly reasonable choice for a simultaneity method. It just doesn’t qualify as a coordinate system.

What does any of this have to do with the title? Einstein was not concerned with assigning relations between specific worldlines. His point was that any coordinate system (or even a non-coordinate method such as you use) is a valid choice. You can assign any age you like to the other worldline relative to an event on yours so long as the remote event chosen as simultaneous is not within the light cones of your event. Einstein would not have suggested a preferred event that is simultaneous, which would have been in contradiction with the lack of ability to determine a preferred frame.