Simple Relativity

[CraigD]

Hi Craig

Sorry for being so slow. I think the particular point I cannot understand is the preferred frame, so perhaps we could just take a look at that for the moment.

…

Where does the absolute frame break down[?] It is hard to accept "there is no prefered frame"

It may be hard to accept, but understanding this consequence of the postulates of special relativity – that physical law and the measured speed of light doesn’t change due to relative velocity – which are supported by all credible experimental results, is essential to understanding physics.

 

I believe some of your difficulty, Ver, is due to describing things that are not simply measurable, and using summary meta-concepts like “is an absolute”. Physics is a useful science largely because it make simple unambiguous, predictions about distinct, measurable events, not meta-concepts such as absoluteness and “the perfect and absolute symmetry of the sphere”.

 

In your last post, I get the impression that you’re not considering length contraction in your thought experiment. Let me try to add some features to clearly illustrate those concepts, and some names to avoid alluding to confusing meta-concepts.

 

Following a famous convention, let’s call one observer Alice, the other Bob.

 

Alice is at the center of and at rest relative a spherical array of reflective bodies 1 light-second (299792458 m) in radius. She has a small device that when triggered emits light for a very brief interval, an accurate clock, and a detector that can detect light reflected by a particular kind of reflector from many distinct directions, directions, including Forward, Backward, Up, Down, Left and Right, where the angle between each of these direction is 90°.

 

Bob is at the center of and at rest relative to an array of detectors just like, except that her detector can distinguish light reflected by it from light reflected by hers and oriented the same as Alice’s, and has a clock and detector just like hers.

 

They are moving at 0.6 c relative to one another, in the direction Forward as measured by Alice, Backward as measured by Bob.

 

Their reflector arrays are sparse enough, and if their elements are physically connected, connected in such a way, that they do not collide or otherwise interfere with one another.

 

At precisely t=0 at both Alice and Bob’s clocks, they are as near as possible to one another, and Alice triggers the light emitter.

 

At t=2 s on her clock, Alice’s detector detects light reflected by her array from all directions (that is, from all of its directionally discrete detectors).

 

At t=2 s on his clock, Bob’s detector detects light from his array all directions.

 

Both Alice and Bob, therefore, conclude that that the light originated from nearly her and his locations the center of their sphere of reflectors.

 

Alice and Bob communicate their findings to one another (by radio, traveling to meet one another over coffee – it doesn’t matter to the thought experiment). A paradox – 2 apparent facts that contradict one another – arise if Alice assumes that Bob’s reflector array has a spherical shape (that is [imath]x^2 +y^2 +z^2 = 1 \,\mbox{ls}[/imath] for each element with coordinates (x,y,z)) when measured by her, and vice versa for Bob.

 

From the detected arrival time of light reflected by Bob’s array (t=1 s at the Backward direction, t=4 s at the forward), however, she calculates that Bob’s reflector is not spherical but rather an ellipsoid with equation [imath]1.25x^2 +y^2 +z^2 = 1 \,\mbox{ls}[/imath], where x is the Forward-Backward axis. Bob performs the same measurements (exchanging the Backward and Forward directions) and calculations, and reaches the same conclusion about the shape of Alice’s detector array.

 

Alice and Bob can deduce, and if their detectors include spectrometers capable of measuring red/blue shift, confirm with measurement, that when it emitted, Alice’s emitter had velocity 0 relative to her, 0.6 c Backward relative to Bob, but this doesn’t lead to the conclusion that her frame is an absolute one, and Bob’s not. The emitter could have traveled with Bob, and except for the red/blue shift measurements, their results and conclusions would have been the same. The emitter could have had non-zero velocity relative to both Alice and Bob, and except for the red/blue shift measurements, their results and conclusions would have been the same.

[Ver]

Hi All!

 

Meanwhile remembering the CraigD question:

 

Who are we?

 

(We are, for example , creators of posts in Hypography.)

 

The above discussion of: Frames Events and Ourselves, has "weight".

 

This means its "speed" is somewhat restricted...

 

It will take "Hypography Time" to receive/understand its Message.

 

Then We are Moments. (modeled perhaps by strings)

 

Summing up: Let thoughts be expressed an understood :)

 

Hi SigurdV

 

Perhaps we are just a product of evolution due to c.

I suppose "weight" is a product mostly of the originating observer.

If you mean "moments" in time, great. Time to stop and study what precisely has happened.

Being able to express "thoughts" is great and even better when someone listens.

[Ver]

Hi Craig.

Yes I have considered the Postulates of Special Relativity and have no concerns about experimental results. Presently, there is no option but to measure and obtain these results. I have no argument with them.

As for length contraction, I have no problem with that and have not made that a consideration for a moving frame because, length contraction is in the direction of travel and using the tabletop in my examples, it is positioned at right angles to the direction of travel and is therefore not length contracted. There is no "length" to any point on the tabletop. See the animation.

 

 

Have a look at this great little animation, it is not mine but it makes one or two points clearer. First, it shows two frames believing they are the center of propagation. second it shows length contraction re the elipse and third, it indicates , if a tabletop is used, then there is no length contraction out at right angles to the direction of travel and fourth it illustrates the disregard to the most important part of the whole animation and that is the "blue" sphere of "propagation"

 

In this little animation, we can see the green man remaining co centered on the blue sphere of propagation and his "reflection" makes him believe so (in a not definitive way). The red lady believes she too is at the center of propagation, which as you can see she is not despite what she believes the experimental results are. She is at the center of the reflection and her tabletop would not have been length contracted. Look at the greater diameter of the elipse.

Now my present View of alice and Bob are that if they are the above animations, then Bobs clock will progress at an absolute time and Alice's clock will progress at .8 of that time due to her speed of .6c relative to the center of the blue sphere. If they were both moving at .3c relative to the center of the "blue" sphere and therefore at .6 relative to each other then time for them will each progress at around .95 of that absolute time or precisely the same as each other.

 

I ask myself, if c is the only absolute in the universe, then what is that point between two opposite heading photons. Surely "That point" is an absolute.