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A good but not perfect example would be Newtonian gravitation. Pre-relativity, if it wasn't for the weird precession of the perihelion of Mercury, one could hav

by kuhewa 4y ago

A good but not perfect example would be Newtonian gravitation. Pre-relativity, if it wasn't for the weird precession of the perihelion of Mercury, one could have easily used a form of this argument to claim Newtonian gravity is a fact because you can do an experiment at any moment to demonstrate it by watching an apple fall from a tree. It's been done millions of times, and the acceleration always follows an elegant equation! We can't always know what we don't know, so falsifiability must remain on the table.

raattgift 4y ago
From the early modern discovery of the finite speed of light in the 17th century (postdating and motivated by the discovery of the Galilean moons). From the beginning (about a decade after Rømer and Huygens published their measurements) Newtonian gravitation was on difficult mathematical grounds because the optical image of a source of gravitation (e.g. the Jovian system and its elements) must lag behind its (Newtonian) gravitational source. Indeed these problems drove corpuscular theories of light, including Newton's own, in which perfectly elastic, rigid, and weightless projectiles travel with finite speed from a source to a target. Early 18th century work on the aberration of light evidenced some of the theoretical problems in Newtonian gravitation (and relatedly interference and diffraction exposed problems in corpuscular theories of light), but almost no practical ones. The practically-measurable non-Newtonian nature of the perihelion precession of Mercury wasn't discovered until at least a couple of decades after Newtonian gravitation exposed the existence of Neptune. For all practical purposes light as a source of gravitational potential (much less the self-gravitation of light) still isn't something we can demonstrate in an Earthbound laboratory (there is ample astrophysical and cosmological support for the active gravitational mass of light, though). Tl;dr Newtonian gravitation was unphysical at its inception, and Newton understood this in correspondence exploring mechanical explanations for the inverse square law. Penultimately, a direct laboratory test of Newtonian gravitation wasn't made until Cavendish's experiment in 1798. Was it "fact" or "effective theory" prior to that test? Did it become "fact" at the time of the test, or did it remain an effective theory? I'm not sure the distinction matters in any practical sense. Finally, > demonstrate [Newtonian gravitation] by watching an apple fall from a tree. Try that in a strong wind!

by kuhewa 4y ago

raattgift 4y ago

From the early modern discovery of the finite speed of light in the 17th century (postdating and motivated by the discovery of the Galilean moons). From the beginning (about a decade after Rømer and Huygens published their measurements) Newtonian gravitation was on difficult mathematical grounds because the optical image of a source of gravitation (e.g. the Jovian system and its elements) must lag behind its (Newtonian) gravitational source. Indeed these problems drove corpuscular theories of light, including Newton's own, in which perfectly elastic, rigid, and weightless projectiles travel with finite speed from a source to a target. Early 18th century work on the aberration of light evidenced some of the theoretical problems in Newtonian gravitation (and relatedly interference and diffraction exposed problems in corpuscular theories of light), but almost no practical ones. The practically-measurable non-Newtonian nature of the perihelion precession of Mercury wasn't discovered until at least a couple of decades after Newtonian gravitation exposed the existence of Neptune. For all practical purposes light as a source of gravitational potential (much less the self-gravitation of light) still isn't something we can demonstrate in an Earthbound laboratory (there is ample astrophysical and cosmological support for the active gravitational mass of light, though). Tl;dr Newtonian gravitation was unphysical at its inception, and Newton understood this in correspondence exploring mechanical explanations for the inverse square law. Penultimately, a direct laboratory test of Newtonian gravitation wasn't made until Cavendish's experiment in 1798. Was it "fact" or "effective theory" prior to that test? Did it become "fact" at the time of the test, or did it remain an effective theory? I'm not sure the distinction matters in any practical sense. Finally, > demonstrate [Newtonian gravitation] by watching an apple fall from a tree. Try that in a strong wind!