July 8th: Archimedes’ Death Ray and Dante’s Inferno: The Real Story of How Galileo Ignited the Age of the Telescope

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365daysDate: July 8, 2009

Title: Archimedes’ Death Ray and Dante’s Inferno: The Real Story of How Galileo Ignited the Age of the Telescope

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Podcaster: Mark Thompson

Organization: Galileo 1610 http://www.galileo1610.com/

Description: To this day, a debate continues concerning Galileo’s role in fueling the so-called conflict between science and religion. But there is another debate, although thankfully it is being conducted with far less angst and vitriol among historians and academicians concerning the methods by which Galileo was able to improve upon an unusual optical device invented in the Netherlands 400 years ago which allowed faraway objects to been seen as if nearby.

Bio: Mark Thompson, a professional cantor and amateur astronomer, has appeared as Galileo on radio, at community theatres and libraries, public schools, colleges and universities throughout the country. He has performed as Galileo for civic organizations, astronomy association conventions, marketing and outreach programs as well as private events and parties since 1996.

Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by Clockwork.

Transcript:

Although Galileo tried to avoid a conflagration, controversy rages to this day concerning the great astronomer’s role in fueling the 400 year-old so-called conflict between science and religion. But there is another debate, although thankfully it is being conducted with far less angst and vitriol among historians and academicians concerning the methods by which Galileo was able to improve upon an unusual optical device invented in the Netherlands 400 years ago which allowed faraway objects to been seen as if nearby.

Was Galileo’s dramatically rapid improvement of the telescope the pre-ordained product of a ruthlessly methodical and mathematical mind? Or was it merely the fortuitous outcome of a desperate and opportunistic man; Berthold Brecht’s so-called hero hell-bent on claiming fame and fortune to keep himself and his family from economic collapse? Perhaps it was a happy conjunction of both?

What do two highly regarded historians have to say? According to William Shea, “Galileo was a talented artisan but until his dying day he remained totally in the dark regarding the laws of optics that lay behind his success.” Albert Van Helden does acknowledge that Galileo was a brilliant experimenter; he did after all figure out that magnification was related to the focal lengths of the two lenses he employed in his fledgling instrument. But how did he do it? Trial and error. Ringing endorsements of Galileo’s prodigious knowledge of optical theory? Not exactly.

Yet even after Galileo published his famous “Siderius Nuncius” wherein he described how he improved the magnification and the quality of the image in his telescope no one could duplicate his efforts — not even Mr. Kepler, who was certainly no “lightweight.” So how was Galileo able to do it?

In his excellent and comprehensive article, “Galileo and the Telescope”, Tel Aviv professor Ya’acov Zik contends that Galileo’s improvements on the telescope weren’t accidental; that he undoubtedly understood the principles of the telescope. Galileo said as much in a letter he wrote to his brother-in-law just one week after his successful demonstration of his 8-power telescope from the Campanile di San Marco in Venice, August 21, 1609. He states unequivocally that his instrument “havere fondamento su la scientia de prospettiva” — in other words it has its foundation in the science of perspective. Zik states that Galileo, being a mathematician, understood prospettiva very well. Measuring things was his forte. He had been tutoring students for years on the use of his military or geometric compass. Zik writes: “from his vast experience of taking measurements on the earth surface, Galileo knew the proper way of representing or drawing objects as done by using a defined proportion scale. It is possible to manipulate the scale and the angle of vision without damaging the realistic representation as long as we are following the formal calculation rules, arithmetical and geometrical. And here’s the intriguing part — Zik concludes that Galileo could easily draw the similarities between his problem and the model of describing a method to measure the height of a tower using a mirror.” Measuring the height of a tower using a mirror? Why does this sound vaguely familiar?

Recall the story of Archimedes’ burning mirror in the siege of Syracuse, sometimes called “Archimedes’ Death Ray” which was also supposedly used to defend Constantinople in 519 A.D. Can you conjure up this image of Archimedes poised on top of a tall tower directing a huge mirror which reflects the sun’s rays directly onto the Roman ships in the sea below setting them ablaze once they were within bowshot?

Yet another Galilean scholar, Sven Dupre, argued that Galileo must have been familiar with the optical properties of concave mirrors in terms of the “punctum inversionis” as it was practiced in 16th century optics since he owned copies of Della Porta’s Natural Magic and DeRefractione and also Ausonio’s Theorica which describes not only the burning properties of a concave spherical mirror, but its image formation and location as well.

It would not have been the first time Galileo would use medieval texts for inspiration and instruction from fiery themes. Recall that Galileo established quite a name for himself as a mathematician early on with the Medicis. Just past his teenage years, Galileo impressed the Florentine Academy with his lectures on Dante’s Inferno. He solved the problem which had vexed all who had preceded him: How do you calculate the size and the shape of Hell? His solution eventually led to one of the most important discoveries in the history of science — the principle of scale invariance, or the idea that, in nature, size matters.

So – is it so unreasonable to assert that perhaps only Galileo was uniquely endowed with the requisite knowledge to transform a toy Dutch spyglass into an instrument whose impact on the world would be of epic proportions?

End of podcast:

365 Days of Astronomy
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The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow…goodbye.

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