HI guys I drew this diagram for another thread but the issue of distance that light travels came up so I thought I'd post it as a separate question:

http://www.paygency.com/Diagrams/RV222.jpg

The diagram shows a ship or object heading towards a light source that has a relative V=0.


Are the distances of both beams of light across distance (d) the same or is one contracted? [object B]

If I understand SRT correctly the light from B's source travells a lesser distance than that of the light from source A.
Is this a correct assessment of the SRT position?

The blue object is stationary with respect to A?
How is distance d defined?

I'm not exactly sure what you're asking, but perhaps this might help:

Assume that at some point, B emits a flash of light toward the blue object.
If the blue object is stationary with respect to A, then the distance travelled by the light flash is longest in A's frame.
If the blue object is stationary with respect to B, then the distance travelled by the light flash is longest in B's frame.


I think we might be talking at cross-purposes.

The diagram poorly shows that B is the whole object including the blue reflector. Like a ship with out windows. B has it's own light source that projects onto the blue wall. "A" is a separate frame and is considered at rest.

The distance is obviously relative to each frame.
For the sake of this question both red beams are continuous and only distance is in question.
BTW nice to see you Pete...

The answer me t'inks is that both A and B will record that the Beams of light travel the same distance from their respective frames perspective. But both frames would record a different distance when compared. A with B

The way I understand relativity phenomena object A will measure the distance d of both light beams the same; that distance will be less than the distance d of both beams measured by object B. I think that also agrees with SRT.

Vern, I think you are correct in what you say about the SRT's solution.

So we have a man aboard our ship [object B] He is looking at the blue wall. What does he see? Does he see two spots of light or only one spot of light according to SRT?
[keeping in mind both beams of light are continuous]

Beam A and Beam B project a spot of red light on the blue wall.

Does a man on object B see the spot created by beam A?

My guess is that the man on object B can see the spot created by beam A just fine according to SRT, and according to what we know about actual relativity phenomena.

My guess is that the man on object B can see the spot created by beam A just fine according to SRT, and according to what we know about actual relativity phenomena.

It can be stated with out any doubt that the man on object B can see the light from his own laser. His laser light can only appear in the NOW of his ship or object. The dot on the wall from his own laser can only appear in the NOW as all light events must occur in between the future and past according to AE's light cones.

It can also be stated with out doubt that an observer aboard Object A can see the spot of light created by object A's laser as that light also appears in the NOW of object A's timeline.

Now the question is : Can both spots of light be seen by both observers if the NOWS are not simultaneous?
According to SRT one spot on teh wall is in the past of the other spot on the wall. It is not important at this stage to determine how far into the past one spot is.
Can we agree that according to SRT this is the case? One spot of light is in the past of the other spot of light?

I don't see any problem with observations of either object A or object B. Object B sees both spots as photons arrive in the NOW of object B. Object A sees the spots as photons arrive in the NOW of object A. The now's don't have to be simultaneous, both A and B see something, and each can apply the Lorentz transformations to predict what the other is seeing.

I guess I'm missing the concept where you see a problem.

It is not easy to describe that's for sure....

The light from Object "A" can appear only in "A's" Now. That Now actually has no duration. The light doesn't linger so to speak. The now is constantly changing.

Object "B" also see it's light in it's now, again the now has no duration.

If Object "A's" light is for example 2 seconds into "B's" past, and only exists at all times in "B's" past how can "B" see "A's" light at all? [given that "B" can only see light in it's NOW.]

As "B's" light exists 2 seconds into "A's" future and always exists in "A's" future by 2 seconds, how can "A" see "B's" light when it is always in "A's" future by 2 seconds.

There is a fundamental issue of time of observation involved. On the premise that observations can only be of the NOW and not some past or future event.

It is not easy to describe that's for sure....

The light from Object "A" can appear only in "A's" Now. That Now actually has no duration. The light doesn't linger so to speak. The now is constantly changing.

Object "B" also see it's light in it's now, again the now has no duration.

If Object "A's" light is for example 2 seconds into "B's" past, and only exists at all times in "B's" past how can "B" see "A's" light at all? [given that "B" can only see light in it's NOW.]

As "B's" light exists 2 seconds into "A's" future and always exists in "A's" future by 2 seconds, how can "A" see "B's" light when it is always in "A's" future by 2 seconds.

There is a fundamental issue of time of observation involved. On the premise that observations can only be of the NOW and not some past or future event.

.......

You misunderstand what SRT predicts. All it says is that if we have two events occur at the same time, but different places, in B's frame, then they happen at different times in A's frame. Time is not absolute. You can't take a particular moment in time, call it NOW, and check what A and B think is happening at that instant, because there's no "time" frame from which to choose it. The best that you can do is, if you're in your own frame observing what's happening, to predict when and where the same events will happen in the frames of A and B, from their perspectives.

If I'm in (an inertial) frame S, and another observer is in a frame S' moving with some constant velocity v along the x axis relative to me, and we're coincident at t=0, and I see an event with coordinates < x, y, z, t >, then they see the same event with coordinates < x', y', z', t' > = <&(x-vt), y, z, &(t-vx/c^2)>, where & = (1-(v/c)^2)^(-1/2).

Data firstly thanks so much for taking my question seriously.

You misunderstand what SRT predicts. All it says is that if we have two events occur at the same time, but different places, in B's frame, then they happen at different times in A's frame. Time is not absolute.

Could it not be argued that time is absolute for our "ray" of light?

I am sure AE placed a light event always in between the past and future. Does this not make time absolute for all photon events?

If a light event is relative in time then obviously my question is easy to answer. Howver if the light event is relative I doubt invariance can exist.

What exactly do you mean by a "light event?" As far as I'm aware, everything I perceive is a direct result of electromagnetic interactions. What special relativity predicts is that every event happens in every inertial frame, but that said events don't have the same simultaneity properties in every frame.

Now, if you were to directly apply special relativity from a photon's perspective, you might decide to argue that in a photon's "rest frame," no time passes, and everything is infinitely thin. This is completely untestable, and has no relevance with respect to what special relativity predicts that other inertial frames will observe, so it's really philosophy, not physics.

If you are aboard object B and you are looking at the blue wall [reflector]
The only way that you can see two light spots is if both light spots share the same NOW as you do. Otherwise one spot is in the past or the future.

http://www.paygency.com/Diagrams/RV222.jpg

SRT's non-simultaneousness means that one light spot is not able to be seen because it's light event is not simultaneous with the other.

If you think about it for a while you will see what I mean. Of course that doesn't mean that you will agree with me biut at least you will see what I mean.

Let's just do an example:

Note that here "dt" means some change in time, not the multiplication of d and t (and dt' does as well). I need more symbols! Also, assume that B is moving relative to A at velocity v along the x axis, from A's perspective. All light beams are directed parallel to the x axis.

Say A and B are synchronized at t = 0. A turns on its light at time t^, and so if the blue plate is D away from A at time t^, then A first sees the light spot appear at time t such that t = t^ + dt where c dt/2 = D - v dt/2 => dt = 2D/(c+v) => t = t^ + 2D/(c+v) and x-coordinate x = D - v dt/2 = D - vD/(c+v) = D(1-v/(c+v)).

So the event that A sees the light spot from its light reflecting on the barrier occurs at spacetime coordinate < x, y, z, t >. Using the Lorentz transformations, we find the coordinate at which B sees the same light turn on. This coordinate is < x', y', z', t' > where

< x', y', z', t' > = < &(x - vt), y, z, &(t - vx/c^2) > (and & is defined as I did earlier)

Now say that B turns on its own light when this happens, so that the coordinate at which B turns the light on (not when the spot appears) in B's frame is < x' - d, y2, z2, t' >. Then the time at which B sees the spot appear at on the wall is t2' = t' + dt' where c dt' = 2d => dt' = 2d / c and the x-coordinate is just x' (the wall is at rest wrt B, and a distance d away). Then using the inverse Lorentz transformation we find out at what time A sees the same event happen. This is at spacetime coord < x2, y2, z2, t2 > in A's frame, where

< x2, y2, z2, t2 > = < &(x' + v t2'), y2, z2, &(t2' + vx'/c^2) > = < &(x' + v(t' + 2d/c), y2, z2, &(t' + 2d/c + vx'/c^2) >

Let's see what the difference in times between when A sees the spot from its own light to when A sees the spot from B's light. This is T = t2 - t:

T = t2 - t = &(t' + 2d/c + vx'/c^2) - t = &(&(t - vx/c^2) + 2 d/c + v&(x - vt)/c^2) - t = &^2 ( t - v^2 t/c^2 ) + 2& d/c - t = (1 - (v/c)^2) t / (1 - (v/c)^2) + 2& d/c - t = t + &(2 d/c) - t = &(2 d/c)

ie. A sees the spot from B's light appear &(2 d/c) later than the spot from its own light. Clearly if A leaves its own light on for longer than &(2 d/c) / (1-2v/(c+v)), then, at some point in time, it will see both spots at the same time. If not, the spot from B will appear after the spot from A has dissapeared (from A's perspective).

If you are aboard object B and you are looking at the blue wall [reflector]
The only way that you can see two light spots is if both light spots share the same NOW as you do. Otherwise one spot is in the past or the future.

SRT's non-simultaneousness means that one light spot is not able to be seen because it's light event is not simultaneous with the other.

If you think about it for a while you will see what I mean. Of course that doesn't mean that you will agree with me biut at least you will see what I mean.

QQ,
You have a funny intepretation of relativity of simultaneity, and are drawing unwarranted conclusions.

Relativity of simultaneity does not mean that observers in different reference frame do not share a "Now".

QQ,
You have a funny intepretation of relativity of simultaneity, and are drawing unwarranted conclusions.

Relativity of simultaneity does not mean that observers in different reference frame do not share a "Now".

It is a bit strange I must admit, but hey in my defence I am a strange guy....ha.....

However Pete you have said something that might help clear my problem up.
Relativity of simultaneity does not mean that observers in different reference frame do not share a "Now".

I have always been under the impression that SRT shows non-simultaneity.

Would you say that diagram 1 Shows SRT's NOWS as correct between two frames with relative velocity? [the grey scale segments represent relative time units]
http://www.paygency.com/Diagrams/relativenow.jpg

I have always been under the impression that SRT shows non-simultaneity.
Can you be more specific, please?
In my understanding, Newtonian mechanics also shows non-simulatenity - because non-simultaneous events exist.

I'm not precisely sure what you diagrams represent. Are they supposed to be graphs of some kind? What is the horizontal axis?


But... assuming that you have time on the vertical axis, I can't actually see any difference between your two diagrams. If time is on the vertical axis, then doesn't every horizontal line across each diagram represent a NOW? One at 12pm, one at 12:01pm, on at 12:02pm, etc, etc, etc???

I am not sure how I can clarify it any more than it is with out further complication. I see the two aspects of time quite clearly but obviously this is not a shared perception.

I shall think on it some more
time is actually on both axis and both axis represent the two "dimensional" nature of time.

Time doesn't have a two-dimensional nature.

Time doesn't have a two-dimensional nature.

ahhh!!! and here in lies my problem in comunication.

I believe that time is in fact 2 dimensional. The passage of time giving the illusion of three dimensional space. [Distance only exists because we percieve it takes time to travel that distance.]

Data, how would you describe the dimensionality of time?

I drew this diagram for another thread some time ago that attempts to show the 2 dimensional nature of time.As you look at the diagram imagine that the plane on the left that is cloured blue with the word Furue written on it, is 2 dimensional and on the other side of that plane is a yellow side which symbolises the Past. In between the two sides of the plane is the NOW symbolised by looking side on at the plane as shown in the center of the diagram. The plane is not discernable but the past, NOW and future exist all the same.
http://www.paygency.com/Diagrams/6.jpg

The passage of time takes this 2 dimensionality and creates the illusion of 3 dim. space. yet space retains it's 2 dimensionality.

So in the NOW we have zero dimensionality, when the past and future are included we have 2 dimensionality, when we include the passage of time [change] we have 3 dimensionality.

Sorry if I am confusing every one.....

if all movement was absolutely suspended the universe would dis-appear, and achieve zero dimension.

ahhh!!! and here in lies my problem in comunication.

I believe that time is in fact 2 dimensional.

Do you base that on observation, on tested theory, or is it just another woolly idea?

simlpe logic actually but inspiration taken from AE.

Can't see the past, can't see the future....what can we see?

Just watch TV for a moment with the thought in mind and you will see what i mean....

simple logic actually
Spell it out for us. Try to explicitally define all your premises.

Spell it out for us. Try to explicitally define all your premises.
there is not a lot to spell out Pete.

tell me : What do you see when you see? What moment of time exists for you?

To put together a completed time and dimension thesis that conforms with a clarified SRT maybe the long term ambition but certainly this is not what I am about in this thread.

I just wish to point out that once the most important aspect of time is clarified the understanding of AE inspiration is able to be fully undertaken. IMHO
It also builds the foundations for further understanding of how dimensionally this universe appears to be 3 dimensions and not two or even zero.
And how this may lead to the capitalisation of that dimensionality for our benefit.
Starting from nothing and then proving a moving and change driven universe. From zero dimensions to three and how this is achieved.

I recently stumbled upon this link to a theory put together by a Dr Elliot McGuken. It is called "The theory of moving dimensions". I don't have the terminology to fully understand his contentions however I do know that it proposes similar but in more scientific language. Might be worth a look

Theory of moving dimensions (http://physicsmathforums.com/showthread.php?t=16)
Unfortunately I didn't have the language skills needed to put my thoughts down properly however I feel his words are very close.

there is not a lot to spell out Pete.
I beg to differ. To me, your position is very illogical. That might change if you could spell out your logic.

tell me : What do you see when you see?
There's a few ways that could be answered... here's the intuitive one:
When I 'see', I detect the event of a light ray or rays striking my retina.
I interpret those rays into a representation of the object/s that emitted or reflected those rays.
What moment of time exists for you?
All moments for which I exist. Not all at once, naturally.


I could put more theory into it... for starter's I should acknowledge the travel time of the light rays between their source and my retina. This isn't necessary in most situations, but it is relevant when I'm doing astronomy observations.
From an SR consideration, I should acknowledge that the "moment of time that exists for me" is all moments in my local reference frame for which I exist.

From an SR consideration, I should acknowledge that the "moment of time that exists for me" is all moments in my local reference frame for which I exist.
I note the word "exist" and it's tense. I ask.... and where in time between future and past events does your local reference frame 'exist'?

And then I would ask ....What duration of time is that moment that you exist?

I note the word "exist" and it's tense.
Please don't read anything into the grammar.
I tried to read Dr. Dan Streetmentioner's Time Travelers' Handbook of 1001 Tense Formations, but I gave up at the section on Future Semiconditionally Modified Subinverted Plagal Past Subjunctive Intentional. Sorry about that.

where in time between future and past events does your local reference frame 'exist'
A reference frame is not tied to a single moment. It exists in past, present, and future.

What duration of time is that moment that you exist?
I existed yesterday. I'll exist tomorrow.
My existance spans past, present, and (presumably) future. It isn't limited to a single moment.

QQ asked:
And then I would ask ....What duration of time is that moment that you exist?
The answer depends on ... who is answering. My beautiful mama once told me: "Till I was 25 I lived over the wonderful 8 years!"

ha......ha...it is obvious to me that I have no hope in hell of describing time dimensionality here......ha.....

The past is a memory and the future os a fantasy it is only in that undefinable moment called the NOW that everything actually exists. If you can look at a car traveling by and see it's past and future I will retire my point.

A memory of past nows and an anticipation of future nows but only the present now is were we are at.......and that preszent now has no duration, zero time

Any way i give up ....ha

Hold on for a second maybe this might help
If you draw a line with time increments of trillionths of a second, no lets go all the way to a plank second, say the smallest amount of time unit.

At what point does the future become the past? And at this point how long in time is it?

how long in time does a photon exist in a single location?

How long does anything exists in a single location? Given that there is no absolute rest frame......

does a photon stop for a moment or two or does it simply keep moving at all times....?

QQ,
Did you exist yesterday?

At what point does the future become the past?
At every point. Every point in time is a division between that point's past, and that point's future.
And at this point how long in time is it?
A point has zero length. that's what 'point' means.

QQ,
Did you exist yesterday?

“ At what point does the future become the past? ”

At every point. Every point in time is a division between that point's past, and that point's future.
“ And at this point how long in time is it? ”

A point has zero length. that's what 'point' means.

You asked for the logic of considering time to be two dimensional.

A point has zero length. that's what 'point' means

and so are you suggesting that the event in time in between past and future has length....all the way into yesterday??

I didn't exist yesterday I have only ever existed in the now. Yesterday was where the NOW was and from where the NOW has evolved, but yesterday does no longer exist except as a memory as all yesterdays are.

When I scramble an egg and cook it, does the unscrambled egg still exist? Or is it NOW a scrambled egg that has been cooked?

by QQ:

"When I scramble an egg and cook it, does the unscrambled egg still exist? Or is it NOW a scrambled egg that has been cooked?"
================================================== ==============

All the fundamental particles that made up the unscrambled egg still exist. They have
just rearranged themselves into a different form with the passage of time, and your
manipulation of them. You can only manipulate the particles in the 'NOW', but they
existed in the past and they will exist in your future, though they may look like shit.

ha you haven;t see the way I cook...shit is an understatement. However I agree that the fundamental particles may still exist but the configuration and location has changed. I might add that there could be plenty of arguement as to whether a fundamental particle itself doesn't change over time simply due to the change in forces over that time.

Still my point stands. Our egg is abviously scrambled and cooked. IT no longer exists as it did, and even if we didn't scramble the egg and left it on the table it is constantly changing as it goes off......and decays.....[eggtropy they call it....ha]

You asked for the logic of considering time to be two dimensional.
Yes... so where is it?

I didn't exist yesterday
Do you want to reconsider that statement?

Yesterday was where the NOW was and from where the NOW has evolved, but yesterday does no longer exist except as a memory as all yesterdays are.
Yesterday was a set of NOWs, all different to the NOW at this moment... and this... and this.

At any moment, only one NOW exists. But that doesn't deny that other NOWs did exist, or will exist. A single dimension is sufficient to give such a continuum of NOWs, each with their own independent existence.

Why do you think that two time dimensions are required?

At any moment, only one NOW exists. But that doesn't deny that other NOWs did exist, or will exist. A single dimension is sufficient to give such a continuum of NOWs, each with their own independent existence.

You don't see the contradiction in what you have just stated ?

At any moment only one now exists....VS......a continuum of nows each with their own independant existance....

maybe someone can tell me what the scientific term is for the two dimensionality I am suggesting with this scenario:

Take a dual poled bar magnet. Slice of a piece of the bar with zero thickness.
On one side of the slice is the north pole and on the other side is the south and in between is zero. Thus we have a 2 dimesnional volume with 2 sides but no thickness.

I am sure it is called something in science [ apart from BS...ha]

Maybe someone knows the terminology.....

You don't see the contradiction in what you have just stated ?

At any moment only one now exists....VS......a continuum of nows each with their own independant existance....
No contradiction.

Consider points on a line:
At any distance along the line from an arbitrary starting place, only one point exists.
There is a continuum of points, each with their own independent existence.