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Author : Rudolf Steiner
Title : The light course First course in natural science : light, color, sound, mass, electricity, magnetism
Year : 1921

Link download : Rudolf_Steiner_-_The_light_course.zip

Translator’s Introduction. On a parent education evening at Green Meadow Waldorf School in New York, the class teacher of the seventh grade demonstrates a first physics experiment for the parents in attendance. Over a Bunsen burner he heats a beaker of water containing a piece of ice. The parents watch in rapt silence for several minutes while tiny bubbles form on the bottom and sides of the beaker. Losing its milky opacity and gradually taking on the transparency of the surrounding water, the chunk of ice becomes more mobile, swimming about slowly in the beaker. Bubbles begin to form around the piece of ice, and, one by one, little bubbles rise from the bottom of the beaker, describing erratic paths to the surface. Soon the chunk of ice is no more than a ghostly semblance of its former self, perceptible only as a fleeting watery “thickness” or as a sensation of movement. Then, with surprising suddenness, the water itself is full of motion and no longer transparent but turbulent with large bubbles that swiftly ascend the sides of the beaker. The water itself appears to flow upward and then toward the center of the surface, where it seems to be sucked down again into the boiling cauldron. Surprisingly, very little steam is generated in this process, but when the teacher turns off the Bunsen burner, steam suddenly becomes visible, rising from the now quiet water, in which there is no more ice to be seen. The ice has “melted.” The parents then offer their observations. What did they see ? ...