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How Big Are Things?
Home     Welcome
small Real
world

big     solar system between galaxy
nano
micro
meter
kilo
Mega
Giga
Tera
Peta
Exa
  Yottameter's Room - looking at a sheet of graph paper
  Ym = 1024 m
look at the entire room
 
galaxy21
 20
19
local stars18
 17
16
between15
 14
13
E's orbit12
 11
10
sun9
 8
7
texas6
 5
4
hood3
 2
1
you0
 -1
-2
salt grain-3
 -4
-5
bacteria-6
 -7
-8
atom-9

1 Ym
10 Ym


source

I am told we currently (early 2001) have position information
out to about 300 Mly from us .
[Yes, this seems at odds with the above redshift map. I may well have its scale wrong.]

The universe is known to be close to Euclidean (ie, graph-paper like)
at least out to 1 Gly. [But I don't know how far beyond that.]

At some point, it becomes unclear whether we can scale the universe to our desktop.
We can draw lines
5 Gly 
10 Gly 
15 Gly 
20 Gly 
30 Gly 
but it is not clear (at least to me) if they are physically meaningful.

With an expanding universe about 15 Gyear old,
a 15 Gly looking-out-into-the-past "lightcone" distance,
might get expanded to something like
a "current" 20-30 Gly graph-paper-like "Robertson-Walker metric" distance,
at least in those Big Bang models where one can say something like this.

Beyond this so-called "visible universe"... is something for a different web site.

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