The discussion revolves around historical and contemporary predictions in mathematics and science that are perceived as misguided or incorrect. Participants explore various examples of such predictions, examining the context and implications of these statements.
Participants express differing views on the nature of predictions and their validity over time. There is no consensus on which predictions are indeed 'dumb' or misguided, and the discussion remains open-ended with multiple perspectives presented.
Some statements made by participants rely on historical context and interpretations that may not be universally accepted. The discussion includes speculative reasoning about the implications of past predictions and their relevance to current scientific understanding.
qspeechc said:Or not to be a buzzkill. There was one physicist who said rocket propulsion would work in space and not many other physicists agreed, their objection being space is a (virtual) vacuum and so rocket propulsion couldn't work. I don't remember the names of the scientists or when this was as it was something I saw in a television program about 8 or 9 years ago.
Ivan Seeking said:Man will never reach the moon regardless of all future scientific advances.
-- Dr. Lee De Forest, inventor of the vacuum tube and father of television.
http://plato.stanford.edu/entries/pineal-gland/The nerves are hollow tubes filled with animal spirits. They also contain certain small fibers or threads which stretch from one end to the other. These fibers connect the sense organs with certain small valves in the walls of the ventricles of the brain. When the sensory organs are stimulated, parts of them are set in motion. These parts then begin to pull on the small fibers in the nerves, with the result that the valves with which these fibers are connected are pulled open, some of the animal spirits in the pressurized ventricles of the brain escape, and (because nature abhors a vacuum) a low-pressure image of the sensory stimulus appears on the surface of the pineal gland. It is this image which then “causes sensory perception” of whiteness, tickling, pain, and so on. “It is not [the figures] imprinted on the external sense organs, or on the internal surface of the brain, which should be taken to be ideas—but only those which are traced in the spirits on the surface of the gland H (where the seat of the imagination and the ‘common’ sense is located). That is to say, it is only the latter figures which should be taken to be the forms or images which the rational soul united to this machine will consider directly when it imagines some object or perceives it by the senses” (AT XI:176, CSM I:106). It is to be noted that the reference to the rational soul is a bit premature at this stage of Descartes' story because he had announced that he would, to begin with, discuss only the functions of bodies without a soul.
Imagination arises in the same way as perception, except that it is not caused by external objects. Continuing the just-quoted passage, Descartes wrote: “And note that I say ‘imagines or perceives by the senses’. For I wish to apply the term ‘idea’ generally to all the impressions which the spirits can receive as they leave gland H. These are to be attributed to the ‘common’ sense when they depend on the presence of objects; but they may also proceed from many other causes (as I shall explain later), and they should then be attributed to the imagination” (AT XI:177, CSM I:106). Descartes' materialistic interpretation of the term ‘idea’ in this context is striking. But this is not the only sense in which he used this term: when he was talking about real men instead of mechanical models of their bodies, he also referred to ‘ideas of the pure mind’ which do not involve the ‘corporeal imagination’.
Descartes' mechanical explanation of memory was as follows. The pores or gaps lying between the tiny fibers of the substance of the brain may become wider as a result of the flow of animal spirits through them. This changes the pattern in which the spirits will later flow through the brain and in this way figures may be “preserved in such a way that the ideas which were previously on the gland can be formed again long afterwards without requiring the presence of the objects to which they correspond. And this is what memory consists in” (AT XI:177, CSM I:107).
Finally, Descartes presented an account of the origin of bodily movements. He thought that there are two types of bodily movement. First, there are movements which are caused by movements of the pineal gland. The pineal gland may be moved in three ways: (1) by “the force of the soul,” provided that there is a soul in the machine; (2) by the spirits randomly swirling about in the ventricles; and (3) as a result of stimulation of the sense organs. The role of the pineal gland is similar in all three cases: as a result of its movement, it may come close to some of the valves in the walls of the ventricles. The spirits which continuously flow from it may then push these valves open, with the result that some of the animal spirits in the pressurized ventricles can escape through these valves, flow to the muscles by means of the hollow, spirit-filled nerves, open or close certain valves in the muscles which control the tension in those muscles, and thus bring about contraction or relaxation of the muscles. As in perception, Descartes applied the term ‘idea’ again to the flow of animal spirits from the pineal gland: “And note that if we have an idea about moving a member, that idea—consisting of nothing but the way in which spirits flow from the gland—is the cause of the movement itself” (AT XI:181; Hall 1972, p. 92). Apart from the just-mentioned type of bodily motions, caused by motions of the pineal gland, there is also a second kind, namely reflexes. The pineal gland plays no role with respect to them. Reflexes are caused by direct exchanges of animal spirits between channels within the hemispheres of the brain. (Descartes did not know that there are “spinal reflexes”.) They do not necessarily give rise to ideas (in the sense of currents in the ventricles) and are not brought about by motions of the pineal gland...
BenVitale said:In the 60s math teachers said that computer will be a tool for engineers, not much use for pure mathematics.
Can you think of any other past or current dumb prediction(s)?
BobG said:Surely the physicists involved had to have existed a few hundred years ago, at least.
phinds said:No, actually this was a highly regarded physics professor at a major university as I recall and it was early in the 1900's. I agree w/ your objection that you just wouldn't think that was possible, but it was a statement about the impossibility of Robert Goddard's rockets to fly in space, BECAUSE THERE'S NOTHING THERE TO PUSH BACK ON. I know what utterly stupid it seems that such a thing could have been said by a physics prof in the 1900's but it was.
BobG said:Surely the physicists involved had to have existed a few hundred years ago, at least. I can understand people making drastically wrong predictions about how some principle will be applied, but this one isn't a prediction - it's a statement about conservation of momentum.
Unless, perhaps, they were making predictions about the ability to generate a chemical reaction strong enough to propel the fuel fast enough for the propulsion to be useful. Having to provide your own oxidizer in the absence of oxygen makes chemical reactions more difficult.
But the latter is an entirely different statement, since even just letting gas or liquid leak out of a fuel tank will provide propulsion - just not enough propulsion to be particularly useful.
In other words, this sounds like a myth with just a bit of truth to it, but with the truth stated in a very misleading way.
ideasrule said:Are you sure you're not remembering this anonymous New York Times editorial from 1920? http://en.wikipedia.org/wiki/Robert_H._Goddard#The_New_York_Times_editorial