Wednesday, January 18, 2017

very heavy and very light

can you explain why the ratio between the Hubble mass (i.e. the mass inside the Hubble volume today for a critical universe) and the Planck mass is about $10^{60}$? why are stars roughly in the middle (on a logarithmic scale)? or even more puzzling: why's the ratio between Hubble and Planck-mass about equal to the ratio between stellar masses and the masses of nucleons?

2 comments:

  1. How's this? 10^60 is the square root of 10^120, which is the cosmological-constant-problem number. It is also the age of the universe in Planck units. Barrow and Shaw have written about this.

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  2. In general, the chapter on large numbers in Edward Harrison's textbook Cosmology: The Science of the Universe is a good introduction to this topic. (I recommend his book as a good introduction to most topics in cosmology; it is better than most introductory books.)

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