JF Ptak Science Books LLC Post 976
“All the fifty years of conscious brooding have brought me no closer to answer the question, 'What are light quanta?' Of course today every rascal thinks he knows the answer, but he is deluding himself.” A. Einstein
“Are not gross bodies and light convertible into one
another, and may not bodies receive much of their activity from the particles
of light which enter into their composition?” I.
Depicting the capacity of sight and nature of light has been both an easy and a knotty problem in the history of science. Over the successive theories on the basis of light the artistic presentation of the phenomenon has been generalized (generally) in a very simple way: by straight lines. There’s certainly nothing wrong with that, the lines are just parenthetic place-holders suggesting direction, not actual descriptors of what light “looks” like.
There are literally hundreds if not thousands of images printed 1550-1850 to call upon to make this point, and I've selected but a few. The first belongs to Jesuit astronomer Christoph Scheiner and which appeared in his Oculusm hoc est: fundamentum opticum...,printed in Innsbruck in 1619. His work is an out-and-out landmark in the history of optics, physiological optics and ophthahlmometry, and provided a springboard for two generations following him, not the least of whom was Rene Descartes. The illustration above is the book's frontispiece, and features four camera obscuras demonstrating four principles of the eye, the middle ground of which is a beam of light
Rene Descartes depicted the interpretation (in his Principles of Philosophy of 1644) of light and its physiological reaction in the brain as follows:
the lines of sight depicting binocular vision, observed (and compressed) by the eye's "particles" and processed by the pineal gland which in turn manipulate the "fluids" in the control of nerves and muscles.
Another example of even greater fame than the iconic image by Descartes is that of the diagram showing the connection between color and its reflective index by Isaac Newton, appearing in his Opticae of 1706.
Another fine example comes from Zacharias Traber's (1611-1679) beautifully illustrated classic of optics (and physiological optics) , Nervus Opticus sive Tractatus Theoricus..., published in Vienna in 1690. Traber is a great collector and synthesizer of the work done during and before his time, using the work of Descartes, Kepler, Schott, Kircher, Scheiner and Aguilon (for example), and then further implementing their ideas especially in the areas of color theory and light refraction. The image certainly reflects Jesuit Traber's religious training, depicting the holy source of light (originating with the almighty force) which directs it to the sun; the light then is left to the inquisitive and playful hands of cherubs who reflect and magnify it, as well as use it to start a fire (from the condensing lens) and observe it through a telescope. The main cherub empties a sack containing a number of different optical tools, no doubt for the playful brethern beneath.
And then of course there is the great, unstoppable, polymathic and sometimes incorrect Jesuit Athanasius Kircher. This image appears in his masterwork Ars Magna lucis et umbrae, printed in Amsterdam in 1671, which deals with light and shadow, optical illusions, color, refraction, projection and distortion, sundials, mirrors, as well as astronomical subjects. Most of these subjects are clearly seen in the engraved frontispiece to the work (below), the source of all of the "rays" of light coming from the godhead, relayed through a telescope, reflected from a mirror, and gathered in a camera obscura.
Other interesting images from the Kircher include this spotlight.