military masking net

[szajtan odwieczny]

> As Michaウ said, it's true that the deviations from homogeneity
are
> small on scales anything much bigger than the Schwarzschild horizon of
> a SMBH   http://adjani.astro.uni.torun.pl:9673/zwicky/SuperMBH
>


> Another problem is that in the 2D balloon, the positive fluctuations
> (the net) are connected in a continuous network, while the negative
> fluctuations (lowest density) are unconnected, separated from one
> another.

Why do you consider that as a problem. That's just what we observe, isn't
it.
Those great cosmic scale filaments extending for hundredths of Mpcs.

>
> In the standard (3D) model, at early times the + and - fluctuations
> are typically of the same typical sizes (e.g. from the hypothesis of
> "gaussian fluctuations"), and the 2D topology of contours of constant
> density ("genus analysis") is connected both for + and - fluctns.

agreed
but in time the curvature evolves, like everything else in this Universe.
In time, because of gravity, matter tends to gather in a strings or clumps
of
higher density, and thus the curvature changes.

>
> If you consider all matter more dense than some value,
>  - a low density value gives a "gruyere (ser) topology"
> - a critical density values gives a "sponge topology"

what is the difference between these two ?
is  it only about the thickness of strings ?

>  - a high density gives a "meatball topology"
>
>  This is impossible to do with a balloon, which is 2D, since the
> topology of constant density "1-surfaces" is 1D.

Let's consider a cross section of a large part of the universe with a plain.
Then we take a pencil and draw all the contours
of a constant matter density (= constant curvature) on that plane. We make a
little step back to see the picture. We will see some distinctive pattern
similar to the one observed for clusters of galaxies. This is the analogy to
that net on the balloon. But strings of the net are not 1D but 2D (they have
width) and in reality 3D, so for the fishing net we should sometimes even
fill up some gaps not allowing the balloon the out stand. This I should call
now a military masking net. The constraint of 2D balloon is as you mentioned
that
- fluctuations are separated. That's right but this is only because that on
2d surface a circle splits it into two regions. So in general this is not a
good model. In 3D we can easily jump from one loop into another, unless
there are walls (also those from that masking net :) but in 3D) - like The
Great Wall.

na razie
bartek.



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