models and magnetism

[Nick Thompson]

Hi Hywel, hi Frank. 

 

I took a little time to search for "data" on my raving that Newton must have used  magnets as a model for his theory of gravitation.  My hypothesis was that Newton  played with magnets as a kid.  To me, the term "mathematical model" is a bit of a misnomer because,  while models can be mathematized, a model is at is core a metaphor to some concrete, tangible, denotable experience that the modeler has had.  Thus, a model train in the hands of a child provides the best metamodel  for a scientific model.  By the way, although the best models are explicit, models can -- and very often are -- implicit, revealed by the words one uses to descibe a phenomenon, as, when one says that a particle has "wants". 

 

Was I correct?  Well, more or less.  Steel magnets, bar magnets, etc., seem to come after newton, not precede him.  However, lodestones, as objects of curiosity, date from 600 BC.    By the 12 century AD, people were using them to magnize needles which could then be floated on water so that they always pointed north.  Compasses were made in that way, early on.  Also, people were from classical times rubbing amber , glass and other substances with furs and cloths to produce objects that attracted and repelled other objects.  I am guessing that given Newton's time, he was strongly influenced by William Gilbert.  Below is a description of Gilbert's role which I gleaned from the website,  http://www.rare-earth-magnets.com/magnet_university/history_of_magnetism.htm

 

thanks, all, for a stimulating discussion. 

 

Nick

 

1600 - Static Electricity (De Magnete)

 In the 16th century, William Gilbert(1544-1603), the Court Physician to Queen Elizabeth I, proved that many other substances are electric (from the Greek word for amber, elektron) and that they have two electrical effects. When rubbed with fur, amber acquires resinous electricity; glass, however, when rubbed with silk, acquires vitreous electricity. Electricity repels the same kind and attracts the opposite kind of electricity. Scientists thought that the friction actually created the electricity (their word for charge). They did not realize that an equal amount of opposite electricity remained on the fur or silk. Dr. William Gilbert, realized that a force was created, when a piece of amber (resin) was rubbed with wool and attracted light objects. In describing this property today, we say that the amber is "electrified" or possesses and "electric charge". These terms are derived from the Greek word "electron" meaning amber and from this, the term "electricity" was developed. It was not until the end of the 19th century that this "something" was found to consist of negative electricity, known today as electrons.

Gilbert also studied magnetism and in 1600 wrote "De magnete" which gave the first rational explanation to the mysterious ability of the compass needle to point north-south: the Earth itself was magnetic. "De Magnete" opened the era of modern physics and astronomy and started a century marked by the great achievements of Galileo, Kepler, Newton and others.

Gilbert recorded three ways to magnetize a steel needle: by touch with a loadstone; by cold drawing in a North-South direction; and by exposure for a long time to the Earth's magnetic field while in a North-South orientation.

 

 

 

 

 

 

Nicholas S. Thompson

Emeritus Professor of Psychology and Ethology,

Clark University ([hidden email])

 

 

 

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[Louis Macovsky, Dynamic BioSystems]

I thought the following from the Ecological Society of America listserve might be of interest to this group.

Tom Horton is a prolific writer about the Chesapeake Bay.

 

---Lou

 

Another nail in the coffin of economic growth, and its fundamental
conflict with biodiversity conservation, should we choose to wield the
hammer.

*Restoration of the Bay a failure and will remain so,”*

*argues environmental writer Tom Horton***  To
 
“The restoration of the Chesapeake Bay is a failure after 25 years and
will remain so until political and environmental leaders stop embracing
rapid, unending growth,” says environmental writer Tom Horton.

In his study he argues: “A fatal blind spot remains in the best
strategies to save the Bay. The blind spot is our allegiance--some would
say addiction--to perpetual economic growth, and to encouraging an
ever-expanding population of human consumers to support it.

“This is our mantra: Growth is good, or necessary, or at least
inevitable. So unchallenged is this premise that we discuss it little
more than the gravitational force that holds us to the planet."

In the study the longtime Baltimore /Sun/ environmental reporter and
columnist details how both government and environmentalists focus “only
on the impacts of our lifestyles, acting as if it does not matter how
many of us are living around the Bay.”

He makes the point that this approach, though it is vital to the Bay's
restoration, is a half-measure, doomed to fail so long as rapid growth
continues. He challenges the myth that growth is inevitable, or
necessary to achieve economic prosperity, and talks candidly about
foreign immigration, the largest source of population growth.

"By an end to growth," Horton writes, "we do not mean an end to
capitalism, stock markets, innovation, or even greed and corruption, but
rather a shift to economic  /development/ to better serve those already
here versus making endless and expensive accommodations for all who
might be induced to come.

“Ending growth is a debate needing to happen. Once we begin to shift the
lens, to dare to consider alternatives to the current, growth-is-good
mentality, many ‘goods’ will become ‘bads.’         

“Spending on wider roads, more power plants, bigger sewage treatment
plants, now seen as necessary investments to accommodate growth, will
look like taxpayer subsidies to a few sectors of the economy that are
growth's only real beneficiaries.”

Horton argues: “It will be virtually impossible to reclaim our numerous
environmental messes as population continues rising from the current 304
million Americans to a projected half billion shortly after 2050; the
Bay watershed, currently with 17 million people, is adding 1.7 million
every decade.”

A stable population and a steady state economy will not guarantee
environmental or social Utopia, he argues, "but it will give us
breathing room, leave us options we will not otherwise have.

"There is scarcely a problem facing us that can't be solved easier in
the absence of rapid growth."

The report has been prepared on a grant from The Abell Foundation and
can be downloaded from www.abell.org <[hidden email]>.

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