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tags: Shadows
rel:Survey of Shadows Survey Of Shadows Continued
The Philosophy of Shadows
But mark, madam, we live amongst riddles and mysteries - the most obvious things, which come in our way, have dark sides, which the quickest sight cannot penetrate into; and even the clearest and most exalted understandings amongst us find ourselves puzzled and at a loss in almost every cranny of nature’s work Laurence Sterne
The Causal Theory
The causal theory holds that the transaction between the perceiver and the world should be analyzed primarily in terms of the causal relation underlying that transaction. One version of the causal theory claims that a perceiver sees an object only if the object is a cause of the perceiver’s seeing it.
Greeks extracted classical optics from modest principles, drawing s traight lines between the eye and the surface of near physical objects to get Euclid’s comprehensive answers. One objective to the causal theory is that we seem to see things that are not physical objects: shadows, holes, the sky.
Thought
This connection is intriguing. I’ve explored shadows, and holes but the sky is there also. What about viewing the sky as a shadow, or the sky as a hole or some properties they share.
Or consider the shadow your hand casts on this page.
NOTE
Reading an e-book since this is an expensive book. Example of
rel:Bug on Sensor since my screen has no shadow.
Exciting!
Nevertheless, the perception of absences is a phenomenon general to all the senses. For instance, chapter 5 has a section on touching holes. And I think the most profound perception of an absence is hearing silence
According to Locke, we see things indirectly by means of the ideas that those objects cause. Your experience of Westminster Abbey is a representation of Westminster Abbey by virtue of it being caused by Westminster Abbey.
Engineers publishing in The International Journal of Fracture even study absences caused by other absences, as when the spread of a crack is halted by a hole at its leading edge.
The Krak Des Chevaliers (Castle of Knights) in Syria has a covered passageway. When visitors travel through the long stretch of darkness, they emerge suddenly into daylight. The passageway was designed to dazzle invaders.
Our visual system operates by conditioning.
Although generally relegated to a supporting role in constructing the visual scene, shadows can step into the spotlight of attention. Shadows are what we look for on a hot summer day.
Most paintings that include shadows are not optically realistic. The doctoring of photographs is commonly exposed by impossible shadows and by impossible absences of shadows.
Philosophy has a strong conviction that reality is positive:
They think a negative statement such as “There is a permanent absence of light in the Shackleton crater” is really about where the light is rather than where it is not. This intuition has many manifestations. One is the doctrine that negative truths are reducible to positive truths. Hence, negative truths are redundant: reality can be described with a long conjunction of positive statements. After the positive truths are accounted for, nothing further needs to be added. Additionally, it is widely felt that negative statements are subjective; there are negative states of affairs only when there are expectations. A student can be absent only when school authorities presume that the student will be present. The subjectivity of the absence is underscored by its egocentricity; the student is not here (but has not vanished from the universe). We infer that the student is absent from positive features of the classroom. Talk of absences is disguised talk of presences.
Author claims the above are false.
The irreducibility of the negative truths to positive truths was eventually conceded by those who were most in- vested in the reducibility. When the founder of logical atomism, Bertrand Russell, admitted at Harvard that negative facts exist, he claims that a riot nearly ensued. If there is any reduction to be achieved, it will run from positive truths to negative truths. (From a logical point of view, it is more promising to analyze positive truths as the negations of negative truths.)
The Eclipse Riddle
An object that is completely enveloped in a perfectly dark shadow cannot be seen.
Architecture of shadows
Shadows are not mere absences of light. Shadows require light sources plus transparent or translucent regions where light would have entered were it not for objects that block the source. If I lift the red rock, it casts a shadow. But I have not discovered a preexisting shadow
Photographic negatives suggest another argument for the thesis that we see dark things: anything that is visible in a photograph is visible in the negative of the photograph. Dark things are visible as light things in a photographic negative. Therefore, dark things are visible in photographs. Anything that is visible in a photograph can be seen directly. Therefore, we can directly see dark things.
Shadows that survive their casters
The parasitic nature of shadows makes it natural to infer that a shadow is sustained in existence by the continued existence of its originating source. However, shadows can survive the destruction of their originators. Consider a tree that is constantly illuminated as it petrifies into stone. The stone continues the shadow begun by the tree.
Legend of Buddha dying and his shadow lingering in a cave.
If the moon were obliterated during a solar eclipse, its shadow would linger for more than a second on the surface of Earth.
Thought
I appreciate the maximalist shadow theory going on here. I think a shadow still points back to its source in these cases (it’s not really a temporally bound a segmentation from the body), but it’s carried out to an extent that the shadow theory is fully encompassing and starts to make sense again.
We can extrapolate to posthumous shadows that postdate their objects by millions of years. We can also speculate about an infinite past in which a shadow is sustained by a beginningless sequence of objects. As one object is destroyed, an object of the same shape and size seamlessly replaces it. This shadow antedates any object in the sequence and so refutes the principle that every shadow is caused by an object. Shadows are not dedicated dependents. Although slaves to some object or other, they can switch masters.
When the object is destroyed, the leading edge of the dark three-dimensional volume races toward its opposite edge at the speed of light. Small volumes of shade appear to be destroyed at exactly the time that the object is destroyed. But, strictly speaking, shadows last longer than their destroyed casters.
NYC had to be blacked out during WWII as the the cargo ships in the harbor would be backlit by the bright lights of Manhattan.
Kepler viewed mercury when it traveled across the sun. Since Kepler discovered a new opportunity to observe Mercury and that opportunity involved seeing a silhouette of Mercury, seeing the silhouette of an object suffices for seeing the object.
Silhouettes are widely used as iconographic symbols due to their ease of visual matching.
Shadows as pseudoprocesses
If only the shadow meets the skyscraper, the shadow is momentarily deformed but then, after passing the skyscraper, continues on exactly as before, carrying no trace of its encounter with skyscraper.
If a laser beam is swept across a distant object, the spot of laser light can seem to move across the object at a speed greater than c. Similarly, a shadow projected onto a distant object seems to move across the object faster than c. In neither case does the light travel from the source to the object faster than c, nor does any information travel faster than light. No object is moving in these examples.
Seeing Surfaces
O Moon, when I gaze on thy beautiful face, Careering along through the boundaries of space, The thought has often come into my mind If I shall ever see thy glorious behind.
- Edmund Grosse to his housekeeper.
Leonardo da Vinci whittling objection to the assumption that the surface of an object is the outmost material part of an object.
rel:Islands
If the surface is the outmost part of the object, then how can it have any thickness? If it were one millimeter thick, then only the outermost half millimeter could be the outermost part of the object. That have millimeter could not be the outermost part because its outer half could qualify as the outermost. That outer quarter can be itself halved, and so on. Consequently surfaces have 0 thickness, and thus cannot be a material part of an object.
Occlusion All evolutionary accounts start with a proto-eye that is merely sensitive to the presence of light and then develops into a detector of passing shadows. The fi rst seen objects should have been silhouetted fi gures. Only later would we expect objects to be seen by virtue of the light they transmit. Instead of being a marginal form of vision, purely contrastive seeing is the primal form of seeing. Stereotypical seeing is an elaboration of this more basic ability.
Spinning Shadows
A sphere casts a shadow. If the sphere spins, does its shadow also spin? This riddle bears on the classic controversy about how objects change. Endurantists believe that objects persist by being wholly located at different times.
G.E. Moore puzzled by the moving pictures in the cinema. How can we see the actors move if we are only presented with a rapid succession of still pictures?
If they did move, it would be in the same sort of sense in which a shadow moves, which is very similar to that in which a wave moves: no material thing is transferred from one place to the other; but one sur- face after another, is lighted with a degree of illumination less than that which lights surrounding surfaces, and this happens continuously—just as in the case of a wave, a certain form of arrangement of masses of water occurs successively in many different places, & that continuously.
Moore suggests that shadows and waves move only in the sense that “to any normal person they would look to be moving.”
Thought
A spinning color
The night appears to move over us, but it is we who move into the night. The night is the shadow of Earth and thus is uniformly located on the side of Earth away from the sun. We rotate into the night.
A moon shadow (as opposed to the moon’s shadow) is a shadow whose light source is the moon. Moon shadows are seen at night. The night is the shadow of Earth.
Berkeley’s Shadow Thesis Intangibility Premise: All shadows are intangible. Spatial Premise: All shadows have spatial properties (indeed the complete array). Existence Premise: There are shadows. Anti-Berkeleian conclusion: Some intangible things have spatial properties.
There are other candidate counterexamples: fog, rainbows, the sky, heavenly bodies, microscopic entities, and holes.
The smaller the hole, the more its size is overestimated by the finger and especially the tongue. Dental patients who lose a filling often notice that the cavity seems absurdly large when probed by tongue.
The tangibility of holes suggests a (highly hypothetical) way in which the sky can be touched. The sky is like a hole except its volume is dictated by the face of a planet (or other large heavenly body) rather than a lining. The sky projects indefinitely up from the planet, and is bounded by the horizon. The sky inherits the egocentricity of the horizon; when I travel, the sky shifts with shifts in the horizon.
The sky cannot be touched by reaching up. True, the daytime sky appears dome shaped, and the ceilings of domes can be touched. But the sky dome is an illusion. The clouds directly above are nearer than the ones toward the horizon. Because clarity is a sign of proximity, the dome appears to have a flattened top.
Shadowbands
The most common refraction phenomenon for the night sky is the twinkling of stars. This “stellar scintillation” is caused by the lenslike behavior of air currents.
The sun may also twinkle—from the vantage point of other planets outside the solar system. The only time it twinkles from Earth’s vantage point is during solar eclipses. When only a sliver of light remains, the scintillations form shadow bands
The English astronomer George B. Airy recalled seeing his first shadow bands in 1843: “As totality approached, a strange fluctuation of light was seen … upon the walls and ground, so striking that in some places children ran after it and tried to catch it with their hands”
Goethe’s Colored Shadows
Wolfgang Goethe used colored shadows in a controversial challenge to Newton. The Newtonians prevailed. As the victors, they purged Goethe from the annals of color science.
Once the Newtonians review the history of colored shadows, they will be more likely to view “colored shadow” as a misnomer like “peanut.” (Peanuts are not nuts; they are legumes related to peas—a kind of dried fruit related to peas, beans, and alfalfa.)
Author proposes filtow to displace colored shadow.
Goethe’s initial interest in color was ignited by art and natural beauty.
Goethe thinks objects are the primary bearers of color by virtue of the fact that their surfaces are light darkeners. All colors are shadows because all colors result from light being stopped by objects. For instance, grass is green because it darkens most light except green.
Bridget Riley illusions
rel:Holes
To dramatize the fallibility of memory, Bertrand Russell (1921, 159) formulated the hypothesis that the entire universe began five minutes ago complete with “fossil” records, “memories,” etc. These “traces” make everything look like the universe has a long past. All of our beliefs about the past could be mistaken. Russell’s five-minute hypothesis was formulated to raise questions about how we know propositions about the past. But metaphysicians use it to show that some concepts have a causal requirement. Under the five-minute hypothesis, dinosaurs did not make the footprints of ankylosaurs, and so these are not footprints. The foot-shaped cavity exists, but it is only a hole in a rock, not a fossil hole
Shadows cannot pop into existence. They must be caused by shadow casters (even though they have originated by a causal process other than blocking). Every shadow has a history.
Another impossibility is embodied in a poster for episode one of Star Wars, The Phantom Menace. It features a good boy, Anakin Skywalker, casting an evil man’s shadow. This alludes to the fact that Anakin will mature into the villain Darth Vader. Prospective shadows are impossible because things in the future cannot cause events in the past. This may be only a physical impossibility. If time travel is coherent, then your shadow could precede you.
Shadows are more apt to have meaningful shapes than host-only holes because they mimic the shape and movements of their casters.
Black Holes
The existence of black holes was first predicted by the English geolo- gist John Michell. In a paper presented to the Royal Society of London in 1783, Michell calculated that if a star were 500 times bigger than the Sun, light could not achieve the escape velocity needed to be visible to distant observers.
Michelangelo on the fragile beauty of darknessquote
Any place covered, any sheltered room, Whatever any solid circumscribes, Against the sun playing its glittering game. And if she’s overmatched by fire or flame, By the sun she’ll be ravished and deprived, Of her divine look, baser things besides Can break her more or less, even any worm Worm Work - Recasting Romanticism by Janelle Schwartz
Light deprivation has always been a common punishment.
Sound
J. O. Urmson claims, “The sound of Niagara Falls outdates our most cherished antiquities” One complication is that the roar of Niagara Falls has not been continuous.
Is silence impossible?
rel:Silence - John Cage Gomringer’s silencio, an Unlikely Sonnet
Maurice Blanchot writes, “Silence is impossible. That is why we desire it” (1986, 11). Georges Bataille characterizes “silence” as a “slipping” word because it is “the abolition of the sound which the word is; among all words it is the most perverse, or the most poetic: it is the token of its own death”
According to Cage the original audience missed the point:
There’s no such thing as silence. What they thought was silence, because they didn’t know how to listen, was full of accidental sounds. You could hear the wind stirring outside during the first movement. During the second, raindrops began pattering the roof, and during the third the people themselves made all kinds of interesting sounds as they talked or walked out.
Cage reports that 4¢33² was inspired by a trip to the soundproof anechoic chamber at Harvard University. Although he expected silence, he heard a high noise and low noise. The engineer explained that the high noise was the sound of his nervous system in operation, and the low noise was the blood in circulation.
Mark Nyman:
It is a well-known fact that the silences of 4¢33² were not, after all, silences, since silence is a state which it is physically impossible to achieve… . 4’33” is a demonstration of the non-existence of silence, of the permanent presence of sounds around us, of the fact that they are worthy of attention, and that for Cage environmental sounds and noises are more useful aesthetically than the sounds produced by the world’s musical cultures. 4’33” is not a negation of music but an affirmation of its omnipresence.