Ask HN: What scientific phenomenon do you wish someone would explain better? • Hacker News Board

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

#201

Post by graycat » Sun, Apr 26, 2020, 11:14 PM UTC

qubex wrote: post #56

I find most explanations of the Equivalence Principle that lies at the foundation of General Relativity to be very lax. To wit, the idea is that you cannot distinguish whether you are in an accelerated frame or in a gravitational field; alternatively stated, if you’re floating around in an elevator you don’t know whether you’re freefalling to your doom or in deep sideral space far from any gravitational source (thoug…

I have two quite bright nieces. When I was explaining the equivalence principle to them, right away they saw that in the gravitational field of the earth there would be tidal effects and in free space with just acceleration, none.

I had to apologize and say that the explanation was over simplified and really it would work, say, only for some creatures living exactly on the floor of the elevator.

One of the two, at a challenging high school, made Valedictorian (surprise to her parents who didn't know she had long been first in her class) then in college PBK, got her law degree at Harvard, started at Cravath-Swain, went for an MD, and now is practicing medicine. Bright niece.

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

#202

Post by vmception » Sun, Apr 26, 2020, 11:17 PM UTC

Has someone that thought they were taking LSD ever turned into a permanent schizophrenic zombie or in a mental institution, or is it all urban legend. If someone that didn't know they were predisposed to mental illness, is it applicable to dismiss their experience in order to maintain how safe LSD is?

If any of this is true, are there any sources aside from "my friend's friend's brother took too much and now he is....", and what is the scientific explanation and do we know enough about the mind at all?

I feel like LSD has a lot of contradictory information out there, and the proponents feel the need to hand waive concerns away because it is 'completely harmless and leaves your system in 10 hours'. But when nobody knows what they're actually getting because it doesn't exist in a legal framework, then it muddies the whole experience.

People say certain doses can't do more effect than lower doses after a certain threshold. It seems like the same people say "omg man 1000ug you are going to fry your brain!"

What is the truth? If it "just" had an FDA warning like "people with a family history of schizophrenia should not take it", that would be wildly better than what we have today.

Please no explanation about shrooms. Just LSD the 'research chems' distributed as LSD.

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

#203

Post by lpellis » Sun, Apr 26, 2020, 11:18 PM UTC

monocasa wrote: post #87

lpellis wrote: post #37

Bell's theorem. It somehow proves that quantum physics is incompatible with local hidden variables, but I could never see an understandable explanation (for me at least) of just how it works.

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.

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

#204

Post by strbean » Sun, Apr 26, 2020, 11:18 PM UTC

inopinatus wrote: post #134

Why bicycles stay upright. For every authoritative-sounding, in-depth explanation, there is an equally plausible, yet conflicting and contradictory alternative.

My theory: self-correcting action on the front tire when moving forward.

When the wheel pitches to the either side, the road under the bicycle pushes the wheel back to center.

When the bicycle leans to the side, the wheel pitches as well. Now the road under the bicycle pushes the wheel back towards center, but the angle of the tire to the road is also skewed, so the some of the force also gets translated into pushing the bike upright.

It's a little reminiscent of the self-centering action you get when you have a double-cone (or cylinder tapered on both ends) rolling down two rails.

I think if you fixed the front tire so there was no steering, you wouldn't get any stability from speed.

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

#205

Post by [deleted] » Sun, Apr 26, 2020, 11:20 PM UTC

ShamelessC wrote: post #165

CamperBob2 wrote: post #54

I've always had trouble following Searle's Chinese Room argument as it applies to the nature and identification of intelligent action. I've never understood how the Chinese Room shows what its adherents say it shows, so that would be one topic I'd like to see more perspectives on.

"Searle understands nothing of Chinese, and yet, by following the program for manipulating symbols and numerals just as a computer does, he sends appropriate strings of Chinese characters back out under the door, and this leads those outside to mistakenly suppose there is a Chinese speaker in the room. " I have trouble with this too. I think it's actually incorrect, or at least misleading. I think what it's _trying_…

[deleted]

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

#206

Post by augustt » Sun, Apr 26, 2020, 11:20 PM UTC

arkanciscan wrote: post #198

KhoomeiK wrote: post #184

Earlier quoted context omitted.

I had an aha moment with quantum computers a few months ago when reading an article that explained it as probability distributions. I don't think I have the complete understanding in my mind anymore and I wish I had saved the article, but looking into how quantum computers essentially serve as probability distribution crunching machines might help with your understanding.

So can they still do traditional deterministic(?) calculations? Or would that be somewhat akin to using machine learning to do your taxes; possible but just overkill? I've often heard it said that Quantum Computers can crack cryptographic keys by trying all the possible inputs for a hashing algorithm or something handwavey like that. Are they just spitting out "probable" solutions then? Do you still have to try a han…

Here's what Scott Aaronson says in regard to "trying all the possible inputs": https://news.ycombinator.com/item?id=17425474

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

#207

Post by tprice7 » Sun, Apr 26, 2020, 11:20 PM UTC

itcrowd wrote: post #191

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 can't say anything about dinosaurs (in the colloquial definition) because dinosaurs went extinct >>50k years ago and CD doesn't work after such long time spans.

Ok fair enough. I admit I regret this comment and think I posted it a bit hastily, I tried to delete it a few minutes ago but it appears to be too late now. I edited out the part about dinosaurs though.

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

#208

Post by mkl » Sun, Apr 26, 2020, 11:22 PM 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…

> As for the math, there really is no other way to convince yourself that sin(x) and sin(2x) are orthogonal with respect to the product int(f,g,[0,2pi]) other than to try it out https://live.sympy.org/?evaluate=integrate(%20sin(x)*sin(2*x.... Try also with sin(3x) etc. and cos(n*x) etc.

I disagree with that. It's pretty easy to prove it in general by calculating \int_0^{2\pi} sin(mx)sin(nx) dx etc. for m ≠ n.

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

#209

Post by LVB » Sun, Apr 26, 2020, 11:23 PM UTC

Genetics. I still have no intuition for how combining my wife’s and my DNA has resulted in children with traits from both of us. My brain always tries to imagine interleaving two binaries and hoping for a resulting program that works a bit like the two sources, which it of course wouldn’t.

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

#210

Post by kmm » Sun, Apr 26, 2020, 11:24 PM UTC

galimaufry wrote: post #157

contravariant wrote: post #110

Earlier quoted context omitted.

Annoyingly I've always struggled with the precise definition of spin, but to my understanding angular momentum is only conserved if you take spin into account as well. Being quantum mechanical there is some ambiguity in the direction, but in principle it is a vector (except it's a superposition of several vectors, and this superposition is also equal to superpositions of different vectors, I think there is usually on…

> angular momentum is only conserved if you take spin into account as well. Do you know an example of a process that moves angular momentum from one kind of spin to the other?

There's an experiment that transfers that angular momentum all the way up to macroscopic levels. By magnetizing a cylinder of iron, all the spins start pointing in the same direction. By conservation of angular momentum, the cylinder itself has to start spinning in the opposite direction. I'm very fond of this experiment, because it magnifies a strange quantum phenomenon to the classical level.

Spin being an intrinsically quantum mechanical concept, I'm afraid the microscopic mechanism by which that transfer occurs will only be explainable in a quantum mechanical context. Here it will appear as a term in the Hamiltonian coupling the spin of an electron to its motion in a potential.

https://en.m.wikipedia.org/wiki/Einstein%E2%80%93de_Haas_eff...