Chapter 3 - Shedding Some Light

Chapter 3 - Shedding Some Light

The less one knows about the universe, the easier it is to explain �" Leon Brunschvicg 1869-1944

         

 

Before moving into the scientific complexities of the 20^th century, it is worth consolidating the synoptic view created over the past few chapters.  I began this series by asking: ‘What is Energy’; and continued with an examination of the early growth of human scientific thought.  It became apparent that certain human traits and conditions stymied human logic and the development of scientific reflection.  Identified amongst those traits and conditions were religion and spiritual fantasy, economics, politics, cultural needs or desires, and fluctuating levels of human curiosity; not to mention basic professional envy. 

 

Our primary interest is in the area of physics, astronomy and cosmology, so I don’t intend straying too far down a philosophical or psychological path.  However, to achieve the objective of understanding scientific development, we should be cognizant of human needs.  ‘Maslow’s Hierarchy of Needs’ plays a large part in our intellectual development.  Without going too deeply into this phenomenon, suffice to say, Maslow maintained that without a full belly, and the basic needs of life, humans tend not to be too concerned with deeply intellectual or academic matters.  One can imagine many periods of human history where the sole concern was basic survival �" not scientific advancement or idle curiosity.

 

Another aspect worth considering is the difference between ‘scientific development’ and ‘technological development’; two distinctly differing fields of human enterprise.  The Egyptians, for example, were without doubt technologically advanced.  However, they weren’t necessarily scientifically astute!    Quite simply; they made many items that made life easier, without necessarily understanding the scientific principles underpinning them.  Much the same could be said today; many of us drive technologically advanced vehicles, however, few understand what makes them work!

One other point worth consideration: in earlier times, it had been possible, if one were among a privileged few, to ‘know all there was to know’. 

The sum of human knowledge was such that, without modern day distractions, a person could study to ‘understand everything’.  The last statement must be taken cautiously; but reflects how little was understood scientifically.   As the Enlightenment period advanced into the Industrial Revolution, science and physics started to get really serious.  Pandora’s Box inched to open.  Scientists began to specialize in their own areas of interest.  The world was still a large place at the end of the 19^th century, with poor infrastructures.  Nevertheless, progress was made and information started to be collated.

 

By that time, the three classical states of matter, liquid, solids and gas had been investigated seriously.  Those investigations led to study into non-classical states �" glass and crystal etc.  With the coming of quantum physics, the field widened again into low temperature states, high-energy states, very-high energy states and ever onward into other proposed states.

 

Hypothesis built on hypothesis as theories were proven or disproved; perfect unadulterated science thrived.  The First and Second World Wars drove further discoveries �" some more welcome than others.  Year by year, scientists presented the human race with a growing array of deepening mysteries; mysteries that would stretch ordinary mortal mental capacities beyond normal limits.  Some of those discoveries have led us to rethink reality itself.  Take the following examples; I take the liberty of assuming most readers are aware of the properties of an atom in general terms:

 

If one accepts the world human population to be approximately 6,000,000,000 (6x10⁹) �" and the number of atoms in the human body on average to be 7,000,000,000,000,000,000,000,000,000 (7x10²⁷) then the whole human race comprises: 6x10⁹ x 7x10²⁷ = 4.2�-10³⁷ atoms.  Now strip away the outer layers of those atoms, leaving only their nuclei - matter.  The space required to ‘store’ the whole human race is now reduced to something akin to the volume of a sugar lump.  

Or conversely:  the density of a neutron star, about 20km in diameter, is such that one teaspoon of its substance has a mass of about 100 million tons, which is about as much weight as a good-sized mountain. 

The consequential force of gravity, so powerful, that if an object were to fall from just one metre high it would hit the surface of the star at around 2,000 kms per second, or 6,920,179.2 kmph.

 

These statements are tricky for people to comprehend, because they lay outside the confines of ‘common sense’; but remember, ‘common sense’ was once a reason for accepting the geocentric model of the universe!  Today, there are still those who support the notion of a flat earth.  Religion and superstition still retain an iron grip on the human psyche.  Economics often restricts funding for scientific research, and professional jealousy still gets in the way of progress.  Increasingly, politics in this modern age has an unfortunate habit of creating misleading ‘scientific facts’ for purely political ends.  In spite of the negatives, whilst it may have slowed, genuine scientific knowledge continues to develop apace.

 

Having indulged in a little consolidation, we can now examine some of the specific areas of scientific development concerning the nature of the universe.  As we have seen scientific arguments and debates have raged throughout history.  That is the essential strength of science: one must always question the results.  Darwin’s Theory may be termed ‘only a theory’, but since first proposed, all subsequent evidence has only supported the ‘theory’.  Nothing has cast serious doubt upon Darwin’s empirical evidence and ensuing conclusions.  Conversely, the scientific debate that raged for years over the existence of cosmic ether as the medium by which light moved through the universe, was eventually lost; in spite of assertions - there ‘must be something’ in which light could travel.  Common sense again!  Since the Ancient Greeks, it was speculated that light had a finite speed.  Our old champion, Galileo, actually carried out some crude research attempting to establish the speed of light.  Some 70 years later, the Danish astronomer, Ole Roemer estimated the speed of light at about 220,000 km/s; nearly 26% lower than its correct value. 

 

It wasn’t until 1849, that Armand-Hippolyte-Louis Fizeau (1819-1896) made a reasonably successful attempt to establish the actual speed of light.  In coming years, eminent scientists from Leon Foucault to Mittelstaedt through to Bergstrand, in 1951, struggled to achieve a correct result. 

The American, Albert Abraham Michelson (1852-1931), typified the calibre of those whose efforts would lead to an accurate assessment of the speed of light.  Michelson is particularly interesting because his greatest claim to fame was a failed experiment, which lasted an agonising seven years.  Michelson initially set out to prove the existence of the enigmatic substance - ‘ether’.  Finally, he proved beyond doubt that ether didn’t exist. (See Michelson-Morley experiment)  Incidentally, in 1880 �" Michelson estimated the speed of light to be: 2990,910 km/s.  Although incorrect, it was however a respectable estimate.  In 1921-22, Michelson, in association with Francis Pease, became the first to measure the diameter of a star, other than the Sun.  Using an ‘astronomical interferometer’ at the Mt Wilson Observatory, they successfully measured the super-giant star, Betelgeuse.

 

In 1905, Albert Einstein demonstrated that the velocity of light was an essential constant and in fact the definitive speed for any object.  In 1951, using a Kerr Cell shutter, an instrument previously used as early as 1875, Erik Bergstrand put the speed of light at 299,793.1 km/s; an error of just 0.3.  Accumulated knowledge and advances in technology were finally closing the gap on the elusive ancient speculation.  In the second half of the 20^th century, methods such as cavity resonance techniques, and later laser interferometer techniques, ensured increasingly accurate measurements of the speed of light.  In 1983, the metre was redefined to increase the accuracy of various methods of measurement.  The current definition now reads: ‘the metre is the length of the path travelled by light in a vacuum during a time interval of 1/299 792 458 of a second.’  As a consequence of that reclassification the value of the speed of light in a vacuum is now given as 299,792,458 m/s by the International System of Units (SI).  Finally, it is worth remembering, when we talk of the ‘speed of light’ - we are in fact referring to the ‘speed of electromagnetic radiation’.  What we call, visible light is only a small part of that greater electromagnetic spectrum. 

 

Refs:

Encyclopedi, W. t. (2010). State of Matter. Retrieved June 1, 2011, from Wikipedia: http://en.wikipedia.org/wiki/State_of_matter

Fowler, M. (2009). Galileo and Einstein. Retrieved June 2, 2011, from Uva Dept of Physics: http://galileoandeinstein.physics.virginia.edu/

Fowles, G. (1989). Introduction to Modern Physics. Retrieved June 2, 2011, from Physlink.com: http://www.physlink.com/education/askexperts/ae22.cfm

Gibbs, K. (2010). Speed of Light. Retrieved June 10, 2011, from School Physics: http://www.schoolphysics.co.uk/age16-19/Wave%20properties/Wave%20properties/text/Speed_of%20light/index.html?PHPSESSID=325fe609a38643798b41aced112cbcd0

Singh, S. (2005). Big Bang. London: Harper Perennial.

WikiAnswers. (2011). How much would a spoonful of neutron star weigh. Retrieved June 1, 2011, from Answers.com: http://wiki.answers.com/Q/How_much_would_a_spoonful_of_a_neutron_star_weigh

Wikipedia the Free Encyclopedia. (2011). Speed of Light. Retrieved June 10, 2011, from Wikipedia: http://en.wikipedia.org/wiki/Speed_of_light