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Posts Tagged ‘**Mathematical Principles of natural Philosophy**’

### Universe, Physics, Quantification of Earth: From “A short history of nearly everything” by Bill Bryson

Posted May 24, 2011

on:**“A short history of nearly everything” by Bill Bryson**

**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 his General Theory of Relativity and introduced a constant in the formula to account for 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 most of his life, Newton was more serious in alchemy and religion than in anything else.

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 18^{th} century was feverish in measuring Eart: its shape, dimensions, volumes, mass, latitude and longitude, distance from the sun and planets and they came close to the present measurement except its longivity, 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.