Adonis Diaries

Astronomy and cosmology: From “A short history of nearly everything” by Bill Bryson

Posted on: May 24, 2011

“A short history of nearly everything” by Bill Bryson

Astronomy and cosmology

Around 1930, Vesto Slipher was taking spectrographic readings of distant stars at the Lowell Observatory in Arizona and discovered signs of a Doppler shift toward red, which meant that the stars were moving away.

Annie Jump Cannon, known as one of the “Computers” in the 1920′s at Harvard and who was studying photographic plates of stars and making computation, devised a system of stellar classifications still in use today.

Another Computer specialist at Harvard, Henrietta Swan Leavitt, noticed that a type of star as a Cepheid such as the Pole Star pulsated with a regular rhythm because they are dying giant red star.  Leavitt realized that by comparing the relative magnitude of Cepheids at different points in the sky you could work out where they were in relations to each other in relative distances.

Edwin Hubble began to measure selected points in space and showed in 1923 that M31 was a galaxy at least 900,000 light years away. Hubble inferred in 1930 that galaxies are moving away from us in all directions and that the further away the faster they were moving.

Stephen Hawking said if the universe was static it would collapse in upon itself and would have made the whole cosmos intolerably hot.  It was the Belgian priest-scholar Georges Lemaitre who suggested that the universe began as a geometrical point, a “primeval atom”, which burst into glory and had been moving apart ever since.

In 1965, Arno Penzias and Robert Wilson spent a year trying to shut out a persistent background noise when trying to make use of a large communication antenna owned by Bell Laboratory in New Jersey.  They phoned Robert Dicke at Princeton who was pursuing an idea suggested by George Gamow, a Russian astrophysicist, in the 1940s that if you looked deep enough into space you should find some cosmic background radiation in the form of microwaves reaching Earth originating from the Big Bang.

In 1934 the journal Physical Review published a concise abstract of a presentation that was conducted by Fritz Zwicky and Walter Baade.  Bade was responsible for most of the mathematical sweeping up.  This abstract provided the first reference to supernovae as neutron stars where all the other matters, even electrons, collapsed to the sort of densities found in the core of atoms; no light would penetrate that neutron star or Black Hole star.

A spoonful of a Black Hole star mass would weight 90 billion kilograms.

Very few supernovas explode but when they do then they release enormous amount of energy and matters that keep our universe alive and warm.

Cosmic rays are theorized to be consequences of the explosions of supernovas.

Robert Oppenheimer got all the credit five years later.  Now, if supernovae exploded at a distance less than 500 light years, then Earth is a goner; fortunately, in our near galaxies not a star is at least ten times bigger than our sun to form supernovae.

In 1987, Saul Perlmutter at the Lawrence Berkeley Laboratory used charge-coupled devices, like an excellent digital camera, and wrote a sophisticated program so that the powerful computer would systematically search for supernovas through the thousands of pictures.

Reverend Robert Evans in Australia searches the sky every night using a 16-inch telescope hunting for supernovae and he managed to locate 36 supernovas as of 2003.  How we recognize supernovae?  It is a black star and when we notice light in this dark location then we know a supernova has exploded.  Suppose that you spay salt randomly on 1500 black tables and then you add an extra grain; this is how Robert Evans has the knack of discovering supernovae.

It was Fred Hoyle who coined the term Big Bang in 1952 to express his exasperation of this theory because he favored a steady-state theory.  Hoyle realized that if stars imploded, such as supernovas, they would liberate huge amount of heat in the range of 100 million degrees which favor the formation of heavy elements from carbon onward in a process known as nucleo-synthesis.  His theory explained the existence of heavy elements, at least on Earth, since Big Bangs only releases the lighter elements only.  One of Hoyle’s collaborators W.A. Fowler received a Nobel Prize for this discovery.

Frank Drake, a professor at Cornell, worked out in 1960 an equation designed to calculate the chances of advanced life existing in the cosmos.  There might be millions of intelligent life forms in the cosmos but there are no ways of communicating with them because if any one of these advanced species, say 200 light years away, detects a signal from Earth then it would be looking at humans during the time of the American Revolution with horses and white wigs.

How Earth got to exists? Reginald Daly in the 1940s offered this explanation: about 4.6 billion years ago, 99.99% of the dust and gases swirling wildly in the universe went to making the Sun.

Out of the leftover materials the planets started to assemble in endless random permutations.  In just 200 million years the Earth was essentially formed.  An object the size of mars crashed into Earth and formed the companion Moon from the crust of Earth, thus the fact that there are no heavy elements on the Moon that constitute the core of Earth.

When Earth was about one third of its present size, its atmosphere was leaden with noxious gases like carbon dioxide, nitrogen, methane and sulfur. The carbon dioxide formed a greenhouse effect that prevented Earth from freezing because the Sun was still significantly dimmer and could not heat Earth efficiently.

Comets, meteorites and other galactic debris pelted Earth for a long time while creating water to fill the oceans.

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May 2011

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