Around 1800, Herschel wanted to look at the Sun with his telescope, so to keep from going completely blind used different color filters to darken the image enough to be able to look at it.
What appeared remarkable was that when I used some of [the color filters], I felt a sensation of heat, though I had but little light; while others gave me much light, with scarce any sensation of heat.
Almost anyone could have made this observation. The point is what do you do next.
An amateur might think about this for a while, might even come up with a hypothesis involving an inverse relationship between "brightness" or "color" and "heat."
An amateur, if he is sufficiently motivated, might even be tempted to investigate this, which is what Herschel did.
Herschel refracted light through a glass prism.
And measured, with a thermometer, the temperature of each color.
Conducting the experiment this way would be sufficient for an amateur; he might even be pleased with himself for taking it this far. But Herschel wasn't an amateur, he was a scientist. If you're going to do it, do it right: he knew he needed a control. An amateur is satisfied with relative comparisons, "active comparators", "this color hotter is than this one." But Herschel wasn't going to fall for those shortcuts to hell. He placed another thermometer, outside of the spectrum, as a formal control. Actually, that's my mistake: he put two thermometers outside of the spectrum, as controls.
He found that each color had a different temperature, the red being the hottest, violet the coolest.
Take a moment and consider to what extent you knew (or did not know) this, today, with these principles firmly established in our everyday life. Think about what this finding would mean to Herschel. What kind of questions would he ask next?
Because Herschel wasn't an ordinary scientist. He was able to ask questions others would not think to ask. He looked at those colors, the ones that he had measured, and he asked, what is the temperature of the region after the colors?
He wasn't satisfied with what would have been an otherwise worthwhile experiment, nor was he constrained by what he could see and observe.
So? What do you think was the temperature of this region?
He found it to be even hotter than the red.
It's 2009, so you can guess that what he discovered was the infrared region. But you're putting that together already knowing about infrared light. He had to come up with a whole new explanation for why something that wasn't there was hotter than everything else.
An amateur is full of wonder and speculation, tinkering towards the truth but suffering from a lack of knowledge and idleness; he's not even sure if someone else has already made these discoveries. "Is this a worthwhile pursuit?"
A scientist performs experiments to confirm or disprove a hypothesis, and in that way he grinds out the truth.
A genius has three abilities, which are actually the union of amateur and scientist: 1. to know the state of the art, what is known and what is not known. 2. To be able to think "out of the box". 3. To be disciplined enough to concentrate on the tedium of a formal investigation of his wondrous speculations.
1. To know the state of the art. That's not genetic. You have to devote time to the reading and the learning. This is the second biggest problem with the speculation of amateurs, who may come up with a brilliant idea but suffer from self-doubt: "well, somebody must have already thought of this." Its corollary is accepting that what everyone knows is true, because better minds than yours have checked.
Herschel discovered Uranus, which had probably been observed by a billion people over 6 millennia. But he knew that everyone "knew" it was a star, so was able to ask a now obvious question: if it's a star, how come it gets visibly bigger when you magnify it, unlike all the other stars? Hello?
2. To be able to think "out of the box." This may be genetic, but I doubt it. More often it is the result of using one mode of thinking and training from an unrelated discipline. Not to call myself a genius, but if I was a grade focused pre-med, then med school, then residency guy, this blog and its ideas wouldn't exist. Herschel wasn't a mathematician or an astronomer; he was a professional musician. Not amateur musician- professional, as in that's how he earned his living. Raised by a professional oboist father, played oboe, cello and organ, composed 20+ symphonies, director of the Bath orchestra, etc. And then decided to discover Uranus. Sweet.
NB: age is also likely irrelevant. He discovered Uranus at 43. The infrared experiment was at 62. But most scientists, doing the same kind of thinking, year after year, are much more likely to get an endowed chair than make a novel discovery. (Interesting experiment: what if all Chairmen at Universities had to rotate disciplines for six months every five years? Can't be worse than what goes on today.)
3. Discipline and work. This would be the biggest problem with amateurs. Scientists have it in gigantic proportions, but often to the exclusion of free thinking and speculation.
Sure, it took Herschel half a second to ask, "what about the temperature in the dark zone?" but it misses how much work he put into his "amateur" investigations.
The old sayings "success is 1% inspiration, 99% perspiration" or "90% of anything is just showing up" really speak not to the necessity of work, but to the point that most ideas are mediocre and it doesn't matter. Diligent application can make almost anything a success.