Earth is not in the center of the movements of heavenly bodies, but it
is circling together with the planets around sun - this was a truly
scientific progress made by Aristarchos of Samos and it tells us
something about a frame of reference. The last millenium several
coordinate systems, orientation aids, frames of references, with and
without centers and reference directions, were brought up, and each has
it's merits and is true somehow.
Even Claudius Ptolemaeus in returning against better knowledege to a
geo-centric system is right, as he shows the movements, as they look
like from earth - but the appearance, the shine can betray one: no
planet ever moved in epicycles.(He wanted to sell his astrology of
course).
Now, there's a fresh reference-frame, just right for our millenium to
start with, one i never heard of, not even in the theory, wherein the
speed of propagation of light is an absolutum ( as here is every frame
a frame of an observer in equal rights, it's ego-centric). On 11.
October Sam Wormley wrote:
Once light has left its source and during the finite time of propagation
the target originally aligned with that source moves, aberration can
result.
Whatever theory in physics You are fond of , You should think about
this (and may post some results). Light is independent of it's source
and of course independent of it's observer. With starlight still on
it's way to earth some observers are not even born yet, and when
finally observed, the source might be gone and away. Now, taking any
light, not specially starlight, as a reference for the movement of a
target 8or a source too), that's new.
I agree with Sam and i hope, i'm not misinterpretating his views (i'm
not a physicist).
Regards
Hero
PS. Sam wrote this in the thread "Just a millimeter" here in
sci.physics, which i started with the question:
Will the light-spot of a light-beam or laser-beam of ten meters length
(may be sharpenend with a lens) move throughout half a year of
observation just a millimeter or not ?

On 11. October Sam Wormley wrote:
Once light has left its source and during the finite time of propagation
the target originally aligned with that source moves, aberration can
result.

Awakening from nearly total amnesia after a commotio cerebri and
finding yourself drifting in unknown waters, there seems to be nothing
left to You for orientation. But after a while, with some phantasy and
reasoning and experience of life, you start drawing conclusions like:
i can breathe, so i'm still on planet earth and even if there's fog i
can differ between up and down, i can feel the temperature of water and
air, i can taste, that i'm in salty waters. From my inner ear i can
sense some motions like rotation or up's and downs, and with light i
got more, is it daytime or not, may be a bird or a fish can be
observed....
The same seems to be true for us in space, there's no center and no
principal direction, an x-axis is pointing to. And taking as our
reference a pulse of light there seems to be not even time, as we
cannot count the frequency of our waves, just like a surfer riding a
wave. Someone in a train, deep entangled into his thought experiments,
and seeing through the window the landscape flying by, suddenly
disturbed by the conductor, is asking him: "When does the next station
stops at our train?". And so the interaction with something else is
providing information, without it, we don't even know if we are moving
or being at rest. Interaction between the light and bodies (particles
or compounds of them, mostly associated with mass) like gravity or
slowing down the speed of light by passage through gas or water, these
are already quite complex. Just a simple fact is, that the light pulse
has an origin, where it was born and we assume that the interaction
between the source and the light stops and both become independent from
each other, but there's a relation between the source and the light.

Reducing movement of light and bodies to a point movement, that's
reducing to less, what is necessary for understanding.

A conical sector of a sphere with an round segment front and cut of by
another round segment, expanding from the center of the sphere, that's
our experience with a pulse of light.
Three very short pulses of light will expand into three spheres. If
they are concentric, the source didn't move in relation to - the path
of the light. We can express this also this way, the connection of the
three pulses with their origin coincides or not. And the three events
of creation, one after the other and the event, that the light hits a
target and comes to an end, shows that there is change, there is time.
(Somehow the center lies in the past).Notice, we did not consider any
absolute space or time as a reference in this.
(If someone claims, for light their exists no time: creation, movement
on a path and extinction are all happening at the same moment, then he
is distracting too much from reality. He is taking the trace of a
movement drawn on a paper, which has a start and an end, static,
looking only at the result, not the process.)
In some theories there's a lot of formulas used, and we differ between
constants, independent variables and dependent ones, this point of
view might enrich our ideas.
Consider not only changes of position of bodies or points. There's also
movement of movements, or better a propagation of transversal
oscillations, like "the wave" in a stadion, where people raise from
their seats and sitting down, inducing this to their neighbours. In
german carnival people do "schunkeln", moving to and fro their
neighbours, and also everyone can move up one seat in a takt, so we not
only have velocities, frequencies, energies and wavelenght, there's
longitudinal rotations and displacements and inductions, and
transversal amplitude, polarisation and even rotation of polarisation,
we can make use of.


Back to the seas, still drifting with the water masses, the waves
rolling to another direction, the wind blows it's path and the clouds
are having their own way. Are You moving, are You at rest or
accelerated and whereto?
And more, earth is at the same time rotating with 0.5 km/sec at the
aequator, and You have some of this speed, earth with 3o km/sec around
the sun, and with our neighbour stars we are moving towards Hercules
with 20 km/sec. And actually all of these are spiralling around one
another with a speed of 250 km/sec around the center of the milky way.
So, we should ask some astronomers, how they could find this out. And
we can start swimming, experimenting, may be bringing a gyro into
spinning, and else.

Analog to aberration, we can relate our moving light to a target,
taking either one as a reference. And we can do the experiment, i
proposed.

After this, one can think about a target, which is moving to or from
the light and actually there's a lot of theory about this, but not by
reference with light, only frames of observers and sources. And there's
the MMeX, the Michelson-Morley experiment. In the last decades some
clever people developed their laser gyros and they encountered the
"wave lock", which had to overcome by "dithering" or vibrating the
mirrors or pulsing the light. These interactions of electromagnetic
waves, strongest in nearly equal frequencies/wavelength or multiples, a
scattering from one wave into the other (in this case waves moving the
same path in opposite directions), is not only an mathematical addition
or a superimposition of frequencies or wavelenghts, they get so
entangled, that one cannot analyse, seperate, can not find beat
frequencies. This seems to be similar to "standing waves" and
resonation in music. So we could need some re-considerations.
Just unlock from Your theories of the last millenium ( but don't
dispose), get some ideas from the astronomers and the gyros people,
and do some new experiments - add a new taste to the stew, we are all
brewing in our heads.
Have fun
Hero

wrote:
.....
Following Maxwell's proposal, we use the wavelength of light as a
standard for the measurements of length. For time we are counting as
standard reference as uniform motion the oscillations of light. For
orientation and directions there are laser gyros. For constant speed
differences between different objects we measure the red- and blueshift
of light. With Bradley aberration one can measure differences of
directed speeds of one object against a light ray.
So when You regard light in Your reference frame or that of it's
source, You shouldn't forget to take this light as an independent frame
of reference too.
May light not have a heavy weight in Your thoughts
Hero
PS
And don't forget to promote my experiment from "Just a millimeter"