No significant fraction of physicists ever believed consciousness had a special role in quantum mechanics.
This treats mysterious answers as categorically distinct from scientific answers which I think is wrong. Some answers explain less than other answers and the less an answer explains the more mysterious it is. Science replaces answers that explain less with answers that explain more. That is, it replaces mysterious answers with less mysterious answers. Phlogiston is less mysterious than elan vital but more mysterious than modern chemistry. The Standard Model of quantum mechanics explains far, far more than the pantheon of Greek gods- but it is not categorically different.
Adding: I upvoted. It is still a good discussion topic, it's just that answers should be given the way scminux did.
The constant free-fall acceleration used to be "explained" by the inertial mass being equal to the gravitational mass, which was, of course, a mystery in itself. It took General Relativity to show that only one type of mass is needed. Specifically, gravity is not really a force (but a spacetime curvature), and the Newton's second law Fgrav=ma for gravity is only an approximation, valid for not very heavy and not very fast objects.
"Because GR" is a less mysterious answer (thanks, Jack) than the previous model (Newton's universal gravita...
Spontaneous Human Combustion. Somebody living alone gets drunk/has stroke/heart attack spills alcohol/perfume on themselves and a cigarette ignites a fire. The body slumps onto carpet and the body fat together with clothing and carpet form a candle wick effect and a small high temperature fire burns for some hours. Parts of the body with low fat levels (e.g. lower legs) often remain unburned. It's a simple experiment to do with a pig carcass.
Oxygen != heat, or even fire. Fluorine can set things on fire, for example. And of course the wonderful thing about energy is that it can change forms. So phlogiston theory is thoroughly useless, though I agree it's not a really mysterious answer.
"Emergence" or "quantum effects" to explain how the brain works might fall into this category.
I might mention the context of my question: On a different website I got into a debate with someone who thinks that the mind and rationality are mysterious, non-physical things, about which science can never say anything useful. I wanted to give the historical examples of such views being demolished, and found that I couldn't call to mind more than two or three. My hope was that, for future iterations of that debate, I could refer back to a long list of cases; but it seems to be hard to come up with really strong examples of subjects being declared beyond ...
The germ theory of disease cleared away a number of mysterious answers, like humorism, of which terms like "phlegmatic" are a vestige.
Kinda puts a new spin on "I had a pet rock once. It died.", huh?
Mental image: Petunia looking on, half in concern and half in amusement, as five-year-old HJPEV works determinedly to bury a pebble in the backyard. "I know there's no such thing as 'Rock Heaven', Mom, I'm not stupid!"
Say, rather, 'kinda colors my impression of...' or maybe 'kinda gives a different flavor to...'
Is Spontaneous Generation an example of what you are looking for, or an example of something you aren't looking for?
On the first read, it appears to be a mysterious answer, because it doesn't seem to explain anything, but people also performed experiments on it well before it was finally rebutted, which would seem to put it into the phlogiston category.
Relevant sequence posts to save others from searching...
The other is the special (and mysterious) role of the conscious observer in quantum mechanics, which was explained away by demonstrating that rocks can get entangled with electrons just as much as brains can.
I'm curious as to why, given that the Copenhagen Interpretation allowed for this to occur, this demonstration would 'explain away' the CI. The exact mechanism of that reduction is what I'm after: how does that demonstration 'destroy' the mystery which allowed for that demonstration to occur without invalidating 'the mysterious model'?
I find myself confused, is what I'm saying.
The Luminiferous Aether? I'm not too sure how mysterious it was, but it persisted a fair while before being squelched by the march of science.
http://en.wikipedia.org/wiki/Timeline_of_luminiferous_aether
The obvious one nobody's mentioned: the motion of the stars and planets. Supposedly caused by Angels pushing objects in epicycles around the earth, at least until Newton came along.
I am looking for examples of mysterious answers that were eventually explained *away* by science. I can think of two: One is the belief that the behaviour of living things was explained by the mysterious force of elan vital, and not by mere chemistry; which was destroyed by the synthetisation of urea. The other is the special (and mysterious) role of the conscious observer in quantum mechanics, which was explained away by demonstrating that rocks can get entangled with electrons just as much as brains can. Can anyone furnish me with other examples?
I observe in passing that phlogiston is *not* such a mysterious answer. Eliezer is down on it, but I think unjustly so; for people did in fact perform experiments on phlogiston, including the final experiment to find the weight of the phlogiston that had passed out of the burning material and into the byproducts. It turned out that the phlogiston had negative mass... in other words, that the direction of the transfer had been misidentified. But if you think of phlogiston as `negative oxygen', it makes the same predictions as modern chemical theory. This is no worse a mistake than mistaking the direction of the current, a mistake which is *still* enshrined in our sign conventions; it is not a mysterious answer of the form "X->Y" with no details of X given and any value allowed for Y.
However, I digress. Mysterious answers blown away by experiments, anyone?