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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?

#171

Post by kiernanmcgowan »

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.

I had a professor describe a FT as a "dot product of a function against the real signal space". Thus a FT is valued higher at frequencies where the input signal is more "similar" or "in line" with that frequency. Conversely, the FT is zero where there are none of those frequencies in the input signal.

If this helps, then it can also help with understanding other projections such as the Laplace transform (a dot project against the complex signal space).

While this analogy has helped me, I still have no clue why real valued signals result in an even FT.

edit: grammar

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

#172

Post by guerrilla »

hartator wrote: post #151
Crazyontap wrote: post #149

What happens when you actually fall inside a black hole and what is the singularity. I never really understood what happened really when the guy fell inside it in Interstellar and how come he started seeing all those photos. I just accepted it as Hollywood bs. I know my question is based on a movie but would still like to know what will someone witness (assuming of course they somehow live)

Singularity in AI?

No, https://en.m.wikipedia.org/wiki/Gravitational_singularity

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

#173

Post by arkanciscan »

Quantum Computers. Not like I'm five, but like I'm a software engineer who has a pretty decent understanding of how a classical turing machine works. I can't tell you how many times I've heard someone say "qubits are like bits except they don't have to be just 1 or 0" without providing any coherent explanation of how that's useful. I've also heard that they can try every possible solution to a problem. What I don't understand is how a programmer is supposed to determine the correct solution when their computer is out in some crazy multiverse. I guess what I want is some pseudo code for quantum software.

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

#174

Post by vikramkr »

umvi wrote: post #119

I would like to understand how cellular biology processes actually work. Like, how do all the right modules and proteins line up in the right orientation every time? Every time I watch animations, it seems like the proteins and such just magically appear when needed and disappear when not needed [0]. Sometimes it's an ultra-complex looking protein and it just magically flys over to the DNA, attaches to the correct sp…

A few different things help everything work:

1) Compartmentalizing of biological functions. Its why a cell is a fundamental unit of life, and why organelles enable more complex life. Things are physically in closer proximity and in higher concentrations where needed.

2) Multienzyme complexes. Multiple reactions in a pathway have their catalysts physically colocated to allow efficient passing of intermediate compounds from one step to the next.

https://www.tuscany-diet.net/2019/08/16/multienzyme-complexe...

3) Random chance. Stuff jiggles around and bumps into other stuff. Up until a point, higher temperature mean more bumping around meaning these reactions happen faster, and the more opportunities you can have for these components fly together in the right orientation, the more life stuff can happen more quicky. There's a reason the bread dough that apparently everyone is making now will rise faster after yeast is added if the dough is left at room temp versus allowed to do a cold rinse in the fridge. There are just less opportunities for things to fly together the right way at a lower temperature.

3a) For the ultra complex protein binding to the DNA, how those often work in reality is that they bind sort of randomly and scan along the dna for a bit until they find what they're looking or fall off. Other proteins sometimes interact with other proteins that are bound to the DNA first which act as recruiters telling the protein where to land.

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

#175

Post by andrewflnr »

Hawking Radiation. I know just enough to know that the story of "anti-particle of virtual pairs happens to always fall in the hole" is a Lie Told To Children, but the explanations seem to go straight from there to rather dense math and I've never wrapped my head around it.

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

#176

Post by rrss »

knzhou wrote: post #104
stevebmark wrote: post #102

Earlier quoted context omitted.

I have no idea how it works, I don't have an explanation, I just know the one spouted by people doesn't make sense

Well, if you're uncomfortable with LIGO, you're in good company. Once a whole decade went by in physics where people couldn't agree if it would work in principle or not. And it is true that a lot of common explanations are bad (e.g. "it's just a ruler" is not complete by itself because "why doesn't the light get stretched too?"). Nonetheless, today we have a variety of independent explanations. Maybe you'll find this…

Would you say it's accurate to say LIGO is a big interferometer measuring changes in lengths of the arms due to gravitational waves, with some extra analysis to figure why it still works even though the light waves get stretched? Or is OP correct that such an explanation means I "don't have even a slight understanding of how it works" and a correct explanation must "involve higher spatial dimensions (not time)?"

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

#177

Post by guerrilla »

Crazyontap wrote: post #149

What happens when you actually fall inside a black hole and what is the singularity. I never really understood what happened really when the guy fell inside it in Interstellar and how come he started seeing all those photos. I just accepted it as Hollywood bs. I know my question is based on a movie but would still like to know what will someone witness (assuming of course they somehow live)

You should check out PBS Space Time (on youtube), there are several episodes explaining this in different ways.

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

#178

Post by rrmm »

thegabriele wrote: post #166
sgdpk wrote: post #125

Earlier quoted context omitted.

This really depends on the level of math you're expecting for your intuition, but for me it really clicked when I understood it in terms of linear algebra. A function is like a vector, but instead of having two or three dimensions you have a continuous number of them. Adding functions component-wise works just like adding vectors. Just like regular vectors, you can choose to represent functions in a different basis.…

What's the difference between the coefficients of the furier basis and the weights of a neural network ? Both are ways to approximates functions, aren't they?

the difference is the basis that is chosen. Fourier use sin and cos as a basis (or equivalently complex exponentials). You can choose other bases and get wavelets, or hermite functions, or any other particular independent functions.

Weights on neural networks don't have to be independent functions.

Independence gives you a set of mathematical guarantees that insure you fully cover the space you're representing. For example that given a 2 dimensional space, X and Y are pointing in different directions. If they pointed in the same direction you could not fully decompose all vectors on the plane into two coefficients of X and Y.

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

#179

Post by nabogh »

tprice7 wrote: post #168

1. Carbon dating. Sure, I get that carbon decays over time and this changes the proportion of isotopes. But why does this give you any information? That carbon didn’t come into existence just to be in that bone, it was made in the sun billions of years before that, so why does the age of the carbon tell us anything about organic matter? The key fact, which I think is not emphasized enough, is that the ratio of isotop…

Carbon dating works because the level of carbon 14 in an organism is relatively constant while it is alive. This is because carbon 14 is created in the atmosphere not the sun. https://en.m.wikipedia.org/wiki/Radiocarbon_dating

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

#180

Post by fyp »

Crazyontap wrote: post #149

What happens when you actually fall inside a black hole and what is the singularity. I never really understood what happened really when the guy fell inside it in Interstellar and how come he started seeing all those photos. I just accepted it as Hollywood bs. I know my question is based on a movie but would still like to know what will someone witness (assuming of course they somehow live)

I have not read it myself but the answer can probably be found in the book "The Science of Interstellar" [1]

Kip Thorne, a Nobel prize-winning physicist, worked as the science advisor for Interstellar so the hollywood bs is pretty good!

[1]: https://www.amazon.com/Science-Interstellar-Kip-Thorne/dp/03...

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