Adonis Diaries

Posts Tagged ‘Henri Cavendish

A short history of nearly everything , Part 3

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 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 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 its 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 while creating water to fill the oceans.

 Physics, the quantification of Earth, and the Universe

The physicist Michio Kaku said: “In some sense, gravity does not exist; what moves the planets and stars is the distortion of space and time.”  Gravity is not a force but a byproduct of the warping of space-time, the “ultimate sagging mattress”.  This new understanding of the universe that time is an intrinsic dimension as space was offered by Albert Einstein through his Special Theory of Relativity.

Among other principles, Einstein realized that matter is energy that can be released under specific conditions so that energy is defined as the product of mass and the square of the speed of light c = 300,000 km/s.  In his attempt to unify classical and relativity laws, Einstein offered later on his General Theory of Relativity and introduced a constant in the formula to account a stable Universe; Einstein declared that this constant was “the blunder of his life” but scientists are now trying to calculate this constant because the universe is not only expanding but the galaxies are accelerating their flight away from the Milky Way.

In 1684, Edmond Halley, a superb scientist in his own right and in many disciplines and the inventor of the deep-sea diving bell, visited Isaac Newton at Cambridge and asked him what is the shape of the planetary paths and the cause of these specific courses.  Newton replied that it would be an ellipse and that he did the calculation but could not retrieve his papers.  The world had to wait another two years before Newton produced his masterwork: “Mathematical Principles of natural Philosophy” or better known as the “Principia”. 

Newton set the three laws of motion and that for every action there is an opposite and equal reaction.  His formula stated that force is proportional to the product of the masses and inversely proportional to the square of their corresponding distances.  The constant of gravity was introduced but would wait for Henri Cavendish to calculate it.  It is to be noted that Newton was more serious in alchemy and religion than in anything else, most of his life.

Henry Cavendish was born from a dukes families and was the most gifted English scientist of his age; he was shy to a degree bordering on disease since he would not meet with anyone and, when he visited the weekly scientific soirees of the naturalist Sir Joseph Banks, guests were advised not to look him straight in the face or address him directly.  Cavendish turned his palace into a large laboratory and experimented with electricity, heat, gravity, gases, and anything related to matter.  He was the first to isolate hydrogen, combine it with oxygen to form water.  Since he barely published his works many of his discoveries had to wait a century for someone else to re-discover the wheel. 

For example, Cavendish anticipated the law of the conservation of energy, Ohm’s law, Dalton’s law of partial pressures, Richter’s law of reciprocal proportions, Charles’ law of gases, and the principles of electric conductivity; he also foreshadowed the work of Kelvin on the effect of tidal friction on slowing the rotation of the earth, and the effect of local atmospheric cooling, and on and on.  He used to experiment on himself as many scientists of his century did, such as Benjamin Franklin, Pilate de Rozier, and Lavoisier.  

In 1797, at the age of 67, Cavendish assembled John Michell’s apparatus that contained two 350-pound lead balls, which were suspended beside two smaller spheres. The idea was to measure the gravitational deflection of the smaller spheres by the larger ones to calculate the gravitational constant of Newton. 

Cavendish took up position in an adjoining room and made his observations with a telescope aimed through a peephole.  He evaluated Earth weight to around 13 billion pounds, a difference of 1% of today’s estimate and an estimate that Newton made 110 years ago without experimentation.  John Michell was a country parson who also perceived the wavelike nature of earthquakes, envisioned the possibility of black holes, and conducted experiments in magnetism and making telescopes; Michell died before he could use his apparatus which was delivered to Cavendish.

The 18th century was feverish in measuring Earth, its shape, dimensions, volumes, mass, latitude and longitude, distance from the sun and planets and they came close to the present measurement except its mass and had to wait till 1953 for Clair Patterson (a male geologist) to estimate it to 4,550 million years using lead isotopes in rocks that were created through heating.




August 2020

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