How Big Are Things? Home     Welcome	small		Real world	big			solar system		between	galaxy
	nano	micro		meter	kilo		Mega	Giga	Tera	Peta	Exa

Ym = 1024 m

look at the entire room

galaxy		21
		20 19
local stars		18
		17 16
between		15
		14 13
E's orbit		12
		11 10
sun		9
		8 7
texas		6
		5 4
hood		3
		2 1
you		0
		-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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