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

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

#361

Earlier quoted context omitted.

Minute Physics and 3brown1blue did a two part collab that simplifies some of it down to a counting problem that'd be suitable for grade school. https://www.youtube.com/watch?v=zcqZHYo7ONs https://www.youtube.com/watch?v=MzRCDLre1b4

I have seen the example with the polarized lenses in a few places, but they dont explain why (imo) the simplest explanation does not apply. Namely that the lens itself might disturb the phase of the light, which would then mean it can pass through the next lens.

The idea is that polarization is only one of many places where the effect is observed.

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

#363

* Lie algebras and Lie groups - I still don't understand this, what they're used for or how to use them in any practical sense. * Galois Theory - I have a basic understanding of abstract algebra but for some reason Galois theory confounds me, especially as it relates to the inability of radical solutions to fifth and higher degree polynomials * "State-of-the-art" Quantum Entanglement experiments and their purported s…

Probably the best place to get started with Lie groups is to wrap your head around SO(n), which has both a nice geometric interpretation as rotations of n-dimensional space as well as a concrete representation as the space of orthogonal (determinant 1) nxn matrices. With a little matrix calculus you can work out what the tangent directions are at the identity matrix: they’re precisely the skew-symmetric matrices. This is the Lie algebra so(n). Where the Lie group consists of rotations, the Lie algebra consists of directions in which you can rotate something, or really velocities of rotation. This is why classical angular momentum is actually an element of a Lie algebra.

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

#364

Absorption spectra baffle me and I've never seen an explanation that helps me understand. It seems conceptually simple, except the requirement that the energy of an photon exactly match some required energy in order to be absorbed seems really unlikely, since photon energy not a discrete quantity, and varies according to doppler effects and other things. It seems like the vast majority of photons would just fly throu…

> It seems like the vast majority of photons would just fly through the universe without interacting with anything, unless there are other ways for photons to interact with matter besides being absorbed.

Maybe someone who actually knows will chime in, but afaik:

- Most light doesn't have a fixed frequency. If it did, it would have a fixed momentum, but then you would have no idea where it is! Instead it is some superposition of many frequencies. That could be part of the story.

- Light could be stopped by something other than absorption into an individual atom. Metals don't have discrete spectra.

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

#365

Lot's of quantum related phenomenon here, but what keeps bothering me is that while I get it that light is both a wave and a particle, but I have no clue what that means. I mean, a wave of sound, is made from air particles, a wave of ripples in a pond is made of movement of water molecules. In the double slit experiment, it's explained that the single photon has to be "interfering with itself", so I don't get it if b…

I found these two videos very helpful in understanding the quantum nature of light after being stuck in the same spot: https://www.youtube.com/watch?v=zcqZHYo7ONs https://www.youtube.com/watch?v=MzRCDLre1b4 (Watch those in order, because they're a collaboration between two YouTubers)

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

#366
post #236

Sort of meta, but I always shudder when someone says that science has "proven" something. What sets science apart from most other methods of seeking answers is its focus on disproof . Your goal as a scientist is to devise experiments that can disprove a claim about the natural world. This misconception rears its head most prominently in discussions at the intersection between science and public policy. Climate change…

Proof never proves it only implies. People are just bad at weighing how much proof there is and how heavily it implies something. Nuance is inconvenient in policy discussion and public discourse.

Science also doesn't seek disproof. It uses both example and counter example to confirm or deny or increase how much one confirms or denies.

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

#367

The mathematics of training a neural network. I understand how they work once trained, but that you can train them almost seems too good to be true.

A partial answer is that big fully connected neural networks _are_ pretty much untrainable. Neural networks only became successful once programmers started constraining the space they were optimizing over pretty radically (like requiring convolutional layers if you know you are trying to detect something local).

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

#369

Earlier quoted context omitted.

just once i would like to see the realistic animation though even if it's impossible to understand

https://www.youtube.com/watch?time_continue=42&v=uHeTQLNFTgU This comes close -- It shows the jittery thermal motion of this tiny machinery, instead of nice smooth glides.

Oh my that facepalm dreadful. Thank you! That gives me a new high-water mark for misleading biomolecular visualization computer graphics content. Snagged a copy.

When most everything is unmoving, it's "obvious"... well no, not to students, but... there's no pretense of doing anything other than stitching together an extremely selective set of "snapshots", to tell a completely bogus narrative of smooth motion.

Here it seems something like a Maya "jiggle all the things" option has been turned on. Making it sort of kind of look like you're being shown more realistic motion. But you're so not. It's the same bogus smooth narrative, now with a bit of utterly bogus jiggle. Those kinesin legs still aren't flailing around randomly. Nor only probabilistically making forward progress. And the thing it's towing still isn't randomly exploring the entire bloody space it can reach given the tether, between each and every "step". It still looks like a donkey towing a barge, rather than frog clinging to rope holding a balloon in a hurricane.

And given that the big vacuole or whatever should be flailing at the timescale defined by the kinesin feet, consider all those many much smaller proteins scattered about, just hanging out, in place, with a tiny bit of jiggle. Wow - you can't even rationalize that as being selective in "snapshots" - those proteins should just be blurs and gone.

And that's just the bogosity of motions, there's also... Oh well.

So compared with older renders, these new jiggles made it even harder to recognize that all the motion shown is bogus. And not satisfied with the old bogus motion, we've added even more. Which I suggest is dreadful from the standpoint of creating and reinforcing widespread student misconceptions. Sigh.

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

#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 calculating share price?

If a very low-volume stock is listed at $4, and then I offer to buy a share for $100, does the NYSE suddenly start listing its price at $100?

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