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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?

#791

Post by Caylio »

OkayPhysicist wrote: post #639
zander312 wrote: post #493

Why the earth is a sphere.

Systems tend towards low-energy states (because small perturbations keep things from getting stuck at local minima or saddle points. The lowest potential energy configuration for a bunch of particles pulled together by gravity is a sphere, because every point is as close to to the middle as possible.

That decreases potential energy, but doesn't all that extreme pressure heavily increase the thermal or kinetic energy towards the center? So while this configuration decreases the potential energy, doesn't it also increase the thermal/kinetic energy? Is it obvious that the decrease of potential energy "wins" over the increase in thermal/kinetic?

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

#792

Post by andrepd »

iamevil wrote: post #681
andrepd wrote: post #338

Earlier quoted context omitted.

QFT says it's all fields because it is. Particles simply cannot explain the conjunction of quantum mechanics with special relativity.

I am not so sure about that. When you imagine a "particle", what do you see? Do you see a collection of balls?

How do you mean?

To clarify: a "point particle" is an object with no internal structure, that is, it can be fully described by its coordinates wrt time (ignoring relativity for now). This is a concept, a model which explains many phenomena, a model on top of which you can build many theories. It does not, however, explain the conjunction of QM with special relativity.

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

#793

Post by Caylio »

cygx wrote: post #95
daenz wrote: post #75

Why a flat earth is impossible.

Gravity. Gather enough stuff, and you end up with balls (unless you spin things really fast).

Can you prove that earth is enough stuff? Or that it's not spinning fast enough?

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

#794

Post by yfiapo »

c1ccccc1 wrote: post #784
yfiapo wrote: post #722

I'm sure there are great explanations out there but I haven't had time to read up on them, but a few of the space things that always bother me when I watch pop-sci space tv: - "as soon as iron starts to be produced in the core of a star it instantly collapses" - I get that fusing iron costs energy rather than produces it and this causes a collapse.. but can it really be that quick? There are other fusion reactions th…

Not an expert, so take these with a grain of salt: The core of the star is the hottest and most dense part. Greater heat and density make it easier for fusion reactions to run. If suddenly the core is made mostly of iron, then the amount of energy it produces rapidly drops. Even if there are nice, easily fusible hydrogen atoms farther out from the core, they will not be fusing at a very high rate, because the tempera…

Thank you for even trying to answer my rambles! :-)

I think my contention with the iron is the tipping point and how quickly it goes. Pop-sci tv makes it seem like you fused a single iron atom and bam. Maybe it is you fused an iron atom and it is like a day, a year or a thousand years and that adds up; still bam in terms of cosmic timelines but it is not what I hear when I listen and hear "instant collapse".

Thank you for the thoughts on dark matter and energy as well, and the link on radiation pressure, I will read it.

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

#795

Post by lifeformed »

Erlich_Bachman wrote: post #577
lifeformed wrote: post #347

Earlier quoted context omitted.

Masks are for keeping your own particles from spreading far, not the other way around.

As stated, this is not the whole truth. Please stop spreading this myth. This particular myth may actually cost lives. https://smartairfilters.com/en/blog/n95-mask-surgical-preven... https://smartairfilters.com/en/blog/coronavirus-pollution-ma...

Sorry, my comment was not very clear and is prone to misinterpretation. I'm not saying masks don't keep infection out, but rather that the point of society-wide mask adoption is more to keep unwitting spreaders from spreading so widely. I mean it does both, but as I understand it, it's main value is to attenuate sources than vice versa.

I'm in Taiwan where masks are ubiquitous, and have been upset reading about the slow adoption of masks in the West because it was always from a selfish perspective ("do masks protect ME?") whereas here they're worn for a communal purpose ("how do I protect others?"). How effective they are at blocking incoming infection always seemed like a big distraction to me, since it's been clear from the start that it reduces spray from spreaders talking and coughing, which alone is enough of a reason to adopt it widely.

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

#796

Post by gavinray »

vmception wrote: post #709
gavinray wrote: post #696

Earlier quoted context omitted.

Yeah, I think it entirely had to do with my inability to relinquish control and "just let go". Although in this context, that was literally what felt like the fight to survive, instead of "being chill". Ego death commonly is either the most horrendous or most nirvanic thing depending on how readily someone gives in. > when your sense of self has been obliterated and the next moment you are in the body of another mamm…

and that had never happened to you in your other trips?

No, was really strange, I was pretty experienced by then too. Was never the same after.

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

#799

Post by scld »

strgcmc wrote: post #698
scld wrote: post #684

Time dilation with regards to the "no absolute rest frame" in physics. The famous twin thought experiment where one gets in a spaceship, accelerates away from the planet, turns around, and comes back. The twin that stayed on earth is old and the traveling twin is young still. On one hand, I know that time will "pass differently" for each twin....but why is it the twin in the spaceship that ages less? Why isn't it tru…

You're in luck my friend, the Wikipedia article does a rather nice job of describing just this "paradox": https://en.wikipedia.org/wiki/Twin_paradox > In physics, the twin paradox is a thought experiment in special relativity involving identical twins, one of whom makes a journey into space in a high-speed rocket and returns home to find that the twin who remained on Earth has aged more. This result appears puzzling…

Hahah 2 separate sources each for why I'm incorrect and naive. Thanks!

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

#800

Post by wizeman »

sooheon wrote: post #573
kubanczyk wrote: post #145

Earlier quoted context omitted.

Well, I'd recommend to read the whole series. It's not so bad as it sounds. There are so many steps from where you are to appreciating the utter weirdness of Bell's experimental result. Not the weirdness of any theory (or an interpretation, which Many Worlds actually is) but of the basic experimental result. If you are properly amazed by it, rejecting MWI or any crazy-ish borderline-conspiracy theory seems suddenly a…

Why isn't the MWI another form of hidden variables (a supremely non-parsimonious one at that), where the hidden variable is which of the many worlds you happen to inhabit?

I think you can make an argument for viewing it that way, depending on exactly what you mean by "you".

But IIUC, one of the remarkable things about MWI is that it would be a local hidden variable theory!

This is a very important property to have because the principle of locality is deeply ingrained in the way the Universe behaves. Note that (almost?) no other quantum interpretation is both realist and local at the same time.

Maybe you wonder, how is it possible that MWI can be considered a local hidden variable theory if Bell's theorem precisely shows that local hidden variable theories are not possible?

I think that it was Bell himself who said that the theorem is only valid if you assume that there is only one outcome every time you run the experiment, which is not the case in MWI.

This means that MWI is one of the few (the only?) interpretation we have that can explain how we observe Bell's theorem while still being a local, deterministic, realist, hidden variable theory.

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