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Discussion (36 Comments)Read Original on HackerNews
I have multiple environment and science degrees and feel generally knowledgeable and my oldest will put on his best Feynman face and be entirely unsatisfied when I offer and explain “Rayleigh scattering.”
I love it. I love it so much. I love how curious he is. I love how there is so much to not know. I would hate to know it all because I love exploring it with him.
It's just that the energy is spread out over a larger area (brake discs/pads as opposed to a tiny spark) that is also constantly being cooled by air movement, so the energy in any one point is not enough to ignite any of the materials involved. It's why they used to put asbestos in the brake pads, but they now use ceramics and other heat-resistant materials.
Also, engineering.
For a visual spark, it has to be something thrown off which is the right size, material, and a temperature to glow visibly to the human eye under normal light.
For a spark that starts a fire, it has to be something thrown off which has a certain temperature by the time it lands or travels to some other surface.
In both cases, hot very fine particles will cool quickly just by hitting the ambient air. If the underlying surface (e.g. brake disk) gets glowy-hot, we wouldn't call that a spark--it's too big, and fixed.
Oof, the guy who went into the definition of sparks actually makes me realize this question branches off into so many different rabbitholes.
In my experience sparks are generally generated when quite small metal surfaces get in contact at high speeds, meaning they can generate a lot of friction in a very small point, and thus not have enough braking effect despite the local friction in one small point (think rail wheels squeeking in curves).
Brakes OTOH are designed to spread out the friction on a somewhat larger area, which allows more material to take up the friction and the heat, and spread it around.
I know brakes can get extremely hot too though, and after a really hard braking you might have to worry about deformed brakes sometimes.
Race cars tend to have really large breaks (and brake pads) for this reason.
Brakes generate very fine dust that cools off almost immediately.
When a car slams on the brakes the distance is too short to generate enough heat to deform. I would also suspect the treads would partially melt and deform before it catches on fire.
https://yougov.com/en-us/articles/41556-americans-misestimat...
(Although, apparently the poll didn't ask how uncertain they were. The question was, "If you had to guess, what percentage of American adults...")
But like that old axiom about models goes 'All models are wrong, but some are useful.'
The taoists would argue that you shouldn't try to define everything because it will not help out after a certain point.
There needs to be more "prediction depth", vs. explanatory depth. If you can explain something but can't predict what's going to happen, you don't have an understanding of it sufficient for engineering.
This is why economics is not much of a science. Not enough predictive power.
David Deutsch actually argues for Understanding/Explanations over Predictions.
Here is a nice Reddit thread on this; David Deutsch argues that explanation, not prediction, is the primary goal of science. How widely accepted is this view? - https://old.reddit.com/r/PhilosophyofScience/comments/1trw2n...
David Deutsch: A New Way To Explain Explanation - (TED talk) https://www.youtube.com/watch?v=folTvNDL08A and (Transcript of the previous) https://medium.com/dorothyknows/david-deutsch-a-new-way-to-e...
Here he points out that "good explanations" should be "hard-to-vary". What does he mean by this?
It means that "a good explanation" cannot be arbitrarily modified without unraveling its internal coherent structure or contradicting the very facts that it seeks to explain. The evidence and the internal logic that holds up the explanation are tightly coupled together as one organic whole thing.
Then as we move into building a career, we essentially need to understand a topic or field to a degree that we're useful enough to sell it or provide it as a service compared to others.
Do I understand some things more than others? Perhaps. Do I need to understand everything about a particular thing to be knowledge on it, perhaps not.
> Unfortunately, when information is not directly in front of us, our memories and conceptions of it are shaky at best―but our egos are still intact.
I have often found this when as part of my job I have been exposed to a particular area of my field. But years later when presented with questions about it, whilst I can't extract all of the information I have learnt, but if my memory is jogged the information comes back. For example, lets say you learnt a particular skill 5 years ago, but now you struggle to perform it. Egotistically you know you've been able to do it, but your lack of training in recent years prevents you from doing it.
To repurpose a quote originally about believing in good-versus-evil:
> Lord Vetinari gave [Vimes] a friendly smile.
> “Of course, of course,” he said. “You have to believe that, I appreciate. Otherwise you’d go quite mad. Otherwise you’d think you’re standing on a feather-thin bridge over the vaults of Hell. Otherwise existence would be a dark agony and the only hope would be that there is no life after death. I quite understand.” He looked at his desk, and sighed.
-- Guards! Guards! by Terry Pratchett
"As we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say, we know there are some things we do not know. But there are also unknown unknowns - the ones we don't know we don't know."
An excellent quote from Donald Rumsfeld, despite being an absolute cunt.
There was a paper, quite famous now, on the topic titled "Unskilled and Unaware of It: How Difficulties in Recognizing One's Own Incompetence Lead to Inflated Self-Assessments"
Personally, I ran against a closed glass door yesterday. All I hope for is that I was entertaining to onlookers at least.
I recently faced this feeling of overconfidence in knowledge trying to think about how seasons work or why rainbows have a curved or arcing shape.
You might think seasons are caused by the tilt of the earth, but why? Exercise left for the reader.
Wikipedia on Illusion of explanatory depth - https://en.wikipedia.org/wiki/Illusion_of_explanatory_depth
The misunderstood limits of folk science: an illusion of explanatory depth - https://pmc.ncbi.nlm.nih.gov/articles/PMC3062901/
How you can learn in a world of information overload - https://www.youtube.com/watch?v=cbiyPOn-__M
The structure and function of explanations - https://cognition.princeton.edu/publications/structure-and-f...
The Science of a Good Explanation with Tania Lombrozo - https://www.annieduke.com/the-science-of-a-good-explanation-...