Ask HN: What scientific phenomenon do you wish someone would explain better?

Post by partyboat1586 » Mon, Apr 27, 2020, 7:26 AM UTC

JabavuAdams wrote: post #316

kcolford wrote: post #301

Earlier quoted context omitted.

Even diffusion isn't some magical force guiding chemicals through the medium. It's just random movement that statistically results in the chemical being spread out. This is the same principle that the 2nd law of thermodynamics is based upon. There's nothing magic to it, it's just the statistically likely end result over many particles.

Yes. It's interesting how powerful and clarifying this model of its-all-just-atoms-bumping-into-atoms is. It's interesting how many people take science courses, but don't really get this. In the context of Covid19, I see so many people wearing PPE, but failing to act as though they understand that the actual goal is to prevent this tiny virion dust from entering your orifices. Like wearing gloves and a mask, but then…

Post by dijit » Mon, Apr 27, 2020, 7:29 AM UTC

TrackerFF wrote: post #515

robertakarobin wrote: post #370

If I buy a stock, does the price at which I agreed to buy it become the new share price on the stock exchange? Every article on "Where do stock prices come from?" seems to just talk at a high level about supply and demand. But where does the price come from at a nitty-gritty level? Is it an average of all existing offers or something? Do different exchanges and stock-ticker websites have different formula for calcula…

I think the other answers have been good at explaining HOW stock prices are determined at the exchange, but if you're wondering WHY someone would say "That stock is worth $xx.xx", then that's a more complicated question, with equally complicate answers. At the very lowest level, it could be gut feelings from a potential buyer. They see electric cars more frequently, combustion engines going out of fashion, and simply…

Post by javajosh » Mon, Apr 27, 2020, 7:32 AM UTC

ivansavz wrote: post #118

ramboldio wrote: post #55

Fourier Transforms. I'd wish I had a intuitive understanding of how they work. Until then I'm stuck with just believing that the magic works out.

The best way to understand the Fourier transformations is to think of them as change-of-basis operations, like we do in linear algebra. Specifically a change from the "time basis" (normal functions) to the "frequency basis" (consisting of a family of orthonormal functions). Here is the chapter on Fourier transforms from my linear algebra book that goes into more details: https://minireference.com/static/excerpts/four…

Post by aeternum » Mon, Apr 27, 2020, 7:33 AM UTC

vijay_nair wrote: post #483

• Magnetism. There are plenty of videos out there calling it the result of a relativistic charge imbalance. But I've never been able to use this point-of-view to practical use cases like understanding how permanent magnets work or how increasing the number of windings in inductors boosts the magnetic field strength. There were more situations I tried to put this POV into use but I can't remember them off the top of m…

Post by TJSomething » Mon, Apr 27, 2020, 7:35 AM UTC

skosch wrote: post #469

sodafountan wrote: post #454

Earlier quoted context omitted.

I'd assume it's the speed advantage, but the only problem I can think of that would require that type of exponential speed is cracking hashing algorithms which just seems destructive and counterproductive, like building a digital nuclear bomb - and from my very limited understanding that's a long ways off from being achieved. I assume there's probably many more complex computational problems outside of my domain that…

Many problems require lots of huge matrix multiplications—think simulations of physical systems, i.e. weather systems or molecular interactions, or numerical optimization.