Sunday, October 10, 2010

How many stars are in the Universe?

The Hubble Ultra Deep Field
A picture of a piece of the sky equivalent to holding a 1mm square hole at arms length.
Every point of light is a galaxy, and in every galaxy there are approximately 100 billion stars. Multiplying this over the sphere surrounding us, we find an approximate number for the stars in the universe - about 10 to the power of 22.

I'm lucky to have a collection of them in my room. They're made of sixteen square wooden blocks, and represent every star in the observable universe.

Here is one star:

Let me show you how my little universe is constructed.

To start with, each block is identical and has six sides

And each side can be rotated to appear in four different ways

(I gave the full red and white sides four rotations too because they also can noticeably be rotated)

And each block can exist in any of 16 unique and distinguishable locations on the board.

Each block then has 24 (4 x 6) different orientations. Thus with 24 ways each of the 16 blocks can appear, the total number of configurations of all the blocks must be 24 to the power of 16 (I hope!)

"A trillion billion."

One of my favourite stars is this little one

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