Chapter Three — Reverend Evans’ universe
A Short History of Nearly Everything – by Bill Bryson
Chapter 3 – Reverend Evans’ universe
- Only about 6000 stars are visible to the naked eye from Earth, and only 2000 can be seen from any one spot.
- With binoculars, one can see about 50,000 stars, and a small telescope increases that number to about 300,000.
- To reach Alpha Centauri, the closest star to our Sun, would take 25,000 years in a spaceship.
- The average distance between stars in the cosmos is 20 million million miles.
- There are between 100 and 400 billion stars in the Milky Way, and the Milky Way is one of 140 billion galaxies, many of them much larger than ours.
- In the 1960’s, James Drake estimated that there are probably millions of advanced civilizations in our universe.
- If our civilization was randomly inserted into the universe, the chance that we would be on or near a habitable planet would be less than 1 in a billion trillion trillion (10^33).
- Using a 16-inch telescope on his back porch, Evans has found 36 supernovae (up to the year 2003).
- In a typical galaxy containing 100 billion stars, a supernova will occur once every 300 years.
- In a supernova explosion, the mass of a star is compacted into a neutron star and the energy of a trillion hydrogen bombs is released. The explosion is only visible for about a month.
- The core of a neutron star is so dense that a single spoonful of its matter would weigh 200 billion pounds.
- If a supernova explosion occurred within 500 light-years of us, our planet would be destroyed.
- It is supernovae that provide the necessary intense heat (100 million degrees) to forge carbon and iron and other heavy elements, necessary for more complex molecules. The process is known as nucleosynthesis.
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