What most clinicians do when they receive a laboratory report is, of course, to look up the normal range for the tests in question. … Traditionally, a normal range is calculated in such a way that it includes 95% of the results found in a group of normal or healthy persons, and, consequently, there is a 5% risk that a healthy person will present with an abnormal laboratory result. Then, imagine that you do ten tests on a normal person. In that case the risk that at least one of these tests is abnormal is (1 – 0.95¹⁰) which amounts to 0.40 or 40%. If you do twenty-five tests (and that is not uusual in clinical practice), this chance is 72%! As Edmond A. Murphy puts it so aptly, ‘Therefore, a normal person is anyone who has not been sufficiently investigated.’

— Henrik R. Wulff, Stig Andur Pedersen, and Raben Rosenberg, Philosophy of Medicine: An Introduction, 1990, citing Murphy’s The Logic of Medicine, 1976

Spiders are largely blind but experience the world through vibrations in their webs, which they detect with their legs. Now MIT materials scientist Markus Buehler has created a musical impression of that experience. His team made three-dimensional maps of the webs of tropical tent-web spiders, identified the vibrating frequency of each thread, and converted these frequencies into ranges that humans can hear. Threads that are closer to the spider sound louder in the recording.

“The spider web can be viewed as an extension of the body of the spider, in that it lives within it, but also uses it as a sensor,” Buehler told New Scientist. “When you go into the virtual reality world and you dive inside the web, being able to hear what’s going on allows you to understand what you see.”

(Thanks, Colin.)

Leonardo noted that studies of shadow appeal to the same geometric laws as those of perspective — “in matters perspectival, a light source is no different from the eye [… since] the visual ray is similar to the shadowy ray in terms of speed and converging lines.” Just as perspective considers a scene as regarded from a particular point of view, a shadow is a record of what “the lamp cannot see.”

Philosopher Roberto Casati writes, “This is a strong analogy. There is shadow where the light cannot see. Indeed, shadow is exactly what the light source cannot see. A lamp sees only the things that it illuminates; objects in shadow are behind lighted objects that screen the shadow from the lamp’s perspective. For this same reason, when we examine a shadow, we discover the profile of things from the point of view of the lamp. … Shadow allows us to see a point of view other than our own without even getting up from our seats.”

(From Casati’s Shadows, 2000, via Marko Uršič, Shadows of Being: Four Philosophical Essays, 2019.)