Re: Center of Mass of the Universe?
From: EL (hemetis_at_hotmail.com)
Date: 11/16/04
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Date: 16 Nov 2004 03:10:59 -0800
Mcavin@wi.rr.com (Mark Cavin) wrote in message news:<241521ff.0411151425.6485e224@posting.google.com>...
> hemetis@hotmail.com (EL) wrote in message news:<7563cb80.0411150036.6c4ad3d9@posting.google.com>...
> > Mcavin@wi.rr.com (Mark Cavin) wrote in message
> > news:<241521ff.0411141151.4f029aaa@posting.google.com>...
>
> HiYa El,
>
> [EL]
> "It must be more difficult to demonstrate a 3D wave as a surface
> propagating within a volume, but I do have some ideas."
>
> [Mark]
> Exactly, it would be very interesting to "see" a representation of
> wave propagation within the whole of a volume. I wonder if a
> combination of H.O.E arranged in a multiplexed hologram could provide
> some volumetric and animated example of such a view; one that gives
> the impression of a volumetric propagation when the viewer scanned
> back and forth across the image plane. About 1/4 down this page is an
> interesting drawing of a 3d cross section of wave interference
> http://agamemnon.cord.org/step_online/st1-10/st110eii.htm. And then
> there is Rudie Berkhout to study on, he is a master of integrating
> H.O.E in display holography.
> http://rudieberkhout.home.mindspring.com/SPIE-UsingHOEs-tomakeholograms.htm
> IM convincing myself as I write this that it might just be possible.
> L8r,
> Mark
[EL]
Indeed, all combinations of art-physics / art-optics are greatly
appreciated.
Computer generated graphical representations too are very helpful, but
that is not what we may call a visible experiment.
The true problem is that while things may be out there in 3D or 4D
each human eye interacts with light through the array of elements on
the retina.
The retina is basically a surface (a Gaussian Curved Surface).
Although the curvature elements are 3D elements in a 3D coordinate
system, the surface is essentially a 2D entity.
Our visual perception of 3D bodies and the depth element set comes
from the mental comparison between the left-eye right-eye images of
the same scene composition.
A temporal image superposition gives the 3D impression while a
temporal image sequence gives the state of motion.
Let me elaborate a bit, but before I do that I need to recall your
line:
"one that gives the impression of a volumetric propagation when the
viewer scanned back and forth across the image plane."
In that line you wrote, it was clear to me that you are quite aware of
the two functions of binocular vision.
The word volumetric as you have used successfully between the words
"impression " and "propagation " have summarized the whole issue. :-)
Nevertheless, I do have an objection on the "viewer" being able to
"scan" across the image plane.
That concept is an artificial concept by definition and is most
suitable for computer graphics art, representations and
demonstrations.
In an empirical experiment (Laboratory set-up), the scientist must be
aware that what can be exposed to seated audience is the "outer"
surface of the wave-fronts (impression) and the progress of the
interference contour lines (propagation/motion).
The problem is that for any number of concentric spheres there is only
one sphere that we may call the outer sphere, which is the one exposed
to the viewers. Such a perspective is hardly interesting to watch.
What is interesting would be any perception of patterns.
The solution to the problem is in having each spherical wave be
semitransparent (Perhaps 90% transparency) such that a side view would
reveal a succession of decreasing transparency as the number of layers
increase. That transparency may be controlled by controlling the
particle density of the medium in which the wave is set.
Historically, smoke in air and micronic-air-bubbles in water were used
successfully to demonstrate the Helmholtz rings.
From:
<http://www.phys.virginia.edu/classes/252/more_atoms.html>
{
It is fascinating to note that the most exciting theory of fundamental
particles at the present time, string theory, has a definite
resemblance to Thomson's vortex atoms. One of the basic entities is
the closed string, a little loop, which has fields flowing around it
reminiscent of the swirl of ethereal fluid in Thomson's atom. And it's
a very beautiful theory - Kirchhoff would have been enthusiastic!
}
Also, please read about Peter Guthrie Tait at:
<http://www-history.mcs.st-and.ac.uk/~history/Mathematicians/Tait.html>
Air bubbles in water dissipate soon due to the effect of buoyancy,
while smoke particles in motion cannot overcome friction indefinitely.
In search for better representation media a semitransparent "Gel" that
is sensitive to pressure and reacts optically is estimated to be the
best medium.
Sound waves pressure shells set in an optical-gel can demonstrate
those patterns and be recorded on video.
The mathematically expected visual images shall not be more than a set
of hyperbolic contours resulting from two identical waves
interference.
The vibration sources can be as simple as a rubber bubble inside which
incompressible transmission fluid is injected and sucked under the
effect of a vibrating pin. This should periodically change the volume
by expanding and contracting the bubble periodically causing spherical
waves to be generated.
There are already on the market some surface coating materials that
are sensitive to stress and change colour accordingly. Such materials
can be diffused into a silicon based transparent gel to form the ideal
medium for exposing spherical sound waves for demonstration.
Kindest regards.
EL
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