We're in a black hole

Black Holes.

A black hole is an object so dense that its gravitational field is so intense that nothing, even light, can escape its surface.

The size of a black hole, at least one that's not spinning around (rotating), is given by:

^-11

Click here to see why this is so.

Black holes are quite dense. Listed below are the sizes of black holes (or more accurately,
their Schwartzchild radii) for some well known objects:

Object Name	Mass (kg)	Schwartzchild radius
Earth	5.9724 x 10²⁴	0.890911 cm
Sun	1.9891 x 10³⁰	2.953518 km
Deneb	1.2 x 10³²	178.182183 km
Our galaxy	5 x 10⁴¹	4982.723247 AU
Virgo Cluster	10⁴⁴	15.694944 light years
The Universe	10⁵³	1.57 x 10¹⁰light years

The mass of the universe is based on there being about 5 x 10¹¹ galaxies (Based on the Hubble deep field count) and that each galaxy is about half the mass of the our galaxy, the milky way.
The last number, 1.57 x 10¹⁰light years is quite interesting. It's well within the error bars for the current observed radius of the universe.

Our Universe is a black hole!!!

Why this is so is unknown. It might be just a coincidence, or it could have deep physical meaning. No one knows.

The background image used is of the open cluster M67. It comes from the Palomar sky survey I.