What sorts of topics make you feel this way?
Also why, exactly, are they buying the exact assets that they are buying (govt. debt, high-yield bonds, etc..) and why not others (e.g. stocks or put money into startups)? And then, what happens if a debtor pays back its debt? Is that money consequently getting "erased" again (just like it's been created)? What happens if a debtor defaults on its debt? Does that money then just stay in the economy, impossible to drain out? What is the general expectation of the central banks? What percentage of the debt is expected to default and how much is expected to be paid back?
And specifically in the case of central banks buying govt. debt: Are central banks considered "easier" creditors than the public? What would happen if a country defaults on a loan given by a central bank? Would the central bank then go ahead and seize and liquidate assets of the country under a bankruptcy procedure to pay off the debt (like it would be standard procedure for individuals and companies)?
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 (though of course, since you’re in an elevator car and apparently freefalling... I think we’d all agree on what’s most likely, but I digress).
Anyway, what irks me that this is most definitely not true at the “thought experiment” level of theoretical thinking: if you had two baseballs with you in that freefalling lift, you could suspend them in front of you. If you were in deep space, they’d stay equidistant; if you were freefalling down a shaft, you’d see them move closer because of tidal effects dictated by the fact that they’re each falling towards the earth’s centre of gravity, and therefore at (very slightly) different angles.
Of course, they’d be moving slightly toward each other in both cases (because they attract gravitationally) but the tidal effect presents is additional and present in only one scenario, allowing one to (theoretically) distinguish, apparently violating the bedrock Equivalence Principle.
I never see this point raised anywhere and I find it quite distressing, because I’m sure there’s a very simple explanation and that General Relativity is sound under such trivial constructions, but I haven’t been able to find a decent explanation.
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. How to handle a pandemic. Evolution. Abortion. But I've even talked to scientists themselves who from time to time get confused about what science can and can't do.
The problem with believing that science proves things is that it blinds its adherents to new evidence paving the way to better explanations. It also leads to the absurd conclusion that a scientific question can ever really be "settled."
When I took physics they basically said "at first scientists were disturbed by the fact that magnets imply that two objects are interacting without any physical contact, but then Faraday came along and said 'the magnets are actually connected by invisible magnetic field lines' and that resolved everything."
How does saying "but what if there's invisible lines connecting them" resolve anything? To be clear, I'm not objecting to any of the actual electromagnetic laws or using field lines to visualize magnetic fields. It's just that I don't get how invoking invisible lines actually explains anything about how objects are able to react without physical contact.
(Also, it is not lost on me I that this question boils down to "fraking magnets, how do they work?")
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.
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?
1) news articles/lay press - basically terrible and typically get things wrong
2) scientific lay press (scientific american, discover, science news) - get things right, but generally no data/citations or nuance
3) journal summaries - get things right, citations and data for everything. Good summary of the latest scientific thought on a topic. Tend to push a point of view, which generally will be right, but that educated people can debate. Dont always show the data, but at least refer to it. These help you to get up to speed with the primary experiments that were used to establish current thinking.
4) first source articles - typically make claims too broad for the actual results. But has all data. Often times the claims don't follow from the data at all. Generally have to work in the field to understand strengths and weaknesses of methods and you cant just take the conclusions at face value.
As a PhD student, I used #3 a lot to get centered on a space. To understand 4, I typically had to learn directly from my research advisor or other grad students that specialized in an area.
My point here is that you can find these summary articles in journals (microbiology, immunology,virology etc). They are published infrequently so can be hard to find, but they exist and you should look for them.
The StackExchange sites have less coverage and answers tend to be more technical.
University websites return reliable answers, but often neither short nor accessible.
What's the playing field look like for proto-life? How "smart" are the simplest molecular interactions? What does almost-replication look like? Could we use a computational model for this?
Not sure how much of this is known, but I'd love to hear an expert paint a picture of their mental model of the subject.
• Qualia. What is this subjective experience that I know as consciousness? I've gone through Wiki, SEP and a fair number of books on philosophy and a few on neuroscience but I still don't understand what it is that I experience as the color "red" when in reality it's just a bunch of electric fields (photons). Why can't I get the same experience — i.e., color — when I look at UV or IR photons? These too are the very same electric fields as the red, blue, green I see all the time.
• Photographic composition. I'm a designer. I know them. I use them. But only empirically. I just do not understand them at a neuroscientific level. Why does rule-of-thirds feel pleasing? Is the golden ration bullshit? My gut says yes but I'm unable to come up with a watertight rebuttal. Why do anamorphic ultra-widescreen shoots feel so dramatic/cinematic? Yet to see an online exposition on the fundamental reasons underlying the experience. Any questions to artists are deflected with the standard "It's art, not science" reply.
• Wave-Particle duality. "It's a probability wave that determines when a particle will pop into existence out of nothingness." okay, where exactly does this particle come from? If enough energy accumulates in a region of empty space, a particle pops into existence? What is this "energy"? What is it made of? What even is an electron, really? I've followed quite a few rabbit holes and come out none the wiser for it.
• Convolution. It's disappointing how little I understand it given how wide its applications are. Convolution of two gaussians is a gaussian? Convolution in time domain is multiplication in frequency domain and vice-versa? How do these come out of the definition which is "convolution is sliding a flipped kernel over a signal"?
The well known example that if you travel into space you'd gain let's say 5 years and people on earth 25 in the same time or so.
I just don't get it and I can't find any logic explanation.
For instance: Two twins who came to live exactly at the same moment in the year 2000 and both die on their 75th birthday at the same time. One travels into space, the other stays on earth. Earth-brother dies on earthyear 2075,space-brother dies in earthyear 3050 or so...
I know its Einstein's point but that just doesn't instantly make it correct to me.
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)
How immune system and medications work.
Why some plastics are recyclable and others are not.
ZK proofs have a number of good explainers, mostly using graph colorings. Non-interactive versions, however, require quite a bit more than that explanation allows - and despite asking experts, I still haven't found a good, basic explanation.
"You are standing in a field looking at the stars. Your arms are resting freely at your side, and you see that the distant stars are not moving. Now start spinning. The stars are whirling around you and your arms are pulled away from your body. Why should your arms be pulled away when the stars are whirling? Why should they be dangling freely when the stars don't move?"
With the addition of async to django core, I felt its time to finally learn the concept. I first took interest in async early last year when I re-read a medium post on Japronto; an async python web framework that claims to be faster than Go and Node.
Since then, I've been on the lookout for introductory posts about async but all I see is snippets from the docs with little or no modifications and a lame (or maybe I'm too dumb) attempt at explaining it.
I picked up multi threaded programming few weeks ago and I understand (correct me if I'm wrong) it does have similarities with asynchronous programming, but I just don't see where async fits in the puzzle.
Placebo. There are biological bases of it (I don't believe in soul). Find these bases, study them, make a model of them. Then use proxy variables to measure it instead of trying to eliminate it statistically. Predict it in studies to avoid the need of placebo groups (and possibly of double blind methodology). Also, after it is completely measurable and its mechanisms are understood, if (very hypothetical) it has a really substantial effect, just use it to help treat patients.
- "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 that are still producing energy, right?
- dark matter / energy - I understand we have observations that indicate there is some type of matter we can't see but it feels a lot like saying "magic" or "the ether".
- how different size stars form - if there is a critical mass where a star "ignites" and after igniting starts pushing away from itself with the energy being produced, how do we get stars of such varying masses? Like, why didn't this 100x solar mass star start fusing and pushing the gases away before they were caught in its gravity? Do the more massive stars ignite on the same schedule but continue to suck in additional matter anyway, gravity overcoming the solar wind?
If space is expanding why aren’t the radii of fundamental particles and their orbits and molecules also expanding? And if that were the case we couldn’t notice space expanding.
* 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 success in closing all loopholes
* Babai's proof on graph isomorphism being (almost/effectively) in P - specifically how it might relate to other areas of group actions etc.
* Low density parity checks and other algorithms for reaching the Shannon entropy limit for communication over noisy channels
* Hash functions and their success as one-way(ish)/trapdoor(ish) functions - is SHA-2 believed to be secure because a lot of people threw stuff at the wall to see what stuck or is there a theoretical backpinning that allows people to design these hashes with some degree of certainty that they are irreversible?
My current understanding of colour is that the colour of an object is defined by the ability of the electrons in the compound jump different energy levels. I don't know if that in itself is enough to result in all the colour we see.
My current understanding of reflection is that because of wavyness of light when lots of light gets absorbed (to my understanding a single photon exciting a single electron to jump some amount) and reemited (the electron falling back down) together the light ends up forming that angle pattern. Under than understanding single photons don't bounce in the same way rays of light do?
I don't know how correct either of those understandings are, but my understanding has been put together from so many places and I've never heard any source explain either like that so I don't trust they are correct.
The idea is, you can transform a normal [0] wormhole that isn’t a time machine into one which is by:
1) accelerating one end to high speed relative to the other
2) keeping on end in a lower gravitational potential than the other
Why are either of these considered meaningful statements, never mind correct?
In the case of 2 in particular, isn’t GR supposed to require smooth values? So any time dilation effect would be almost identical on a pair of points +δ and -δ from the throat? Making it similar to the case of a gravitational potential without a wormhole?
And in the case of 1, the more I think about it, the less I understand the concept. What is being moved? An imaginary clock that would’ve been in the part of the wormhole at the far end? The apparent speed as measured going through the throat will be zero regardless of the apparent speed of the same as measured when going the long way around.
[0] yes, I know
And adding on to that: Will light inside a box redshift? If I weigh the box (i.e. weigh the light inside the box), then wait a bit for the light to redshift, then weigh the box again?
I understand flight from a mathematical point of view. I've actually read a few books on the subject, and I could explain how flight works to someone. However, I'm still fishing for an explanation that "feels" more satisfying though. Per the question, I still want it explained better.
EDIT: There's already a thread about flight. I asked the same question there, but phrased a bit differently: https://news.ycombinator.com/item?id=22993460
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 through the universe without interacting with anything, unless there are other ways for photons to interact with matter besides being absorbed. (If there are other ways, they are seemingly never mentioned as a potential alternative fate for the photon).
I've been having conversations about viruses recently and in those conversations / thought experiments I keep coming back to a point someone made to me.
Someone this person knows, with extensive medical expertise, explained that the "membrane" of the cell contains a ridiculously large number of unique types of proteins.
Understanding, in vague terms, how viruses penetrate cells the question I pose is "is this true because each of those proteins has a unique and distinct function in the cell membrane? Or is it more a matter of scale and utility?" In other words, does the observation simply indicate that our bodies are not as perfect as we'd like to think they are and the body's process for creating / repairing cells is more a utilitarian function where the "rules" of cell construction are extremely flexible such that these molecules are constructed in various ways where our cells are using materials available to them at the time?
If this is the case it starts to make a lot of sense to me at a molecular level why certain people tend to be more susceptible to contracting certain diseases. Could a lot of it really just come down to diet, along with probably a hint (or more) of DNA's interaction with those proteins we're providing to our bodies? And to what extent does each of those play a role? DNA and the proteins.
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 true that the entire universe accelerated away from the spaceship and then returned, leaving the entire earth young?
The measurements were finally shown to be effects of the immediate environment on the measurement apparatus.
That detectors used in labs may vary with time by >0.1%, unknown to their users, seems pretty important. How did everybody involved not know?
For every authoritative-sounding, in-depth explanation, there is an equally plausible, yet conflicting and contradictory alternative.
I have arthrtic knees, and I'd like a better understanding of how joints work, and where the various clicks, pops and swellings come from.
It's easy to find really simple things, but harder to understand "how things go wrong".
Also are these charges responsible for some weather effects such as the jet stream. In a tornado is the negative charges on the dry side of the dry line interacting with the moist air on the wet side really just a local intense acceleration of the dry air trying to "get to" the oppositely charged moist air?
Are the rotation of low and high pressure systems basically due to the same condition? Is lightning also just basically a flood situation of the charges?
How is it possible that the thread is up 5 hours and ctrl-f consciousness returns nothing?
How does large scale randomness result in such complicated and intelligent systems, while after decades of research and all the computing power we have today, we still struggle to model and reproduce the intelligence of an insect.
So: how to picture this? Is the signal made of discrete 'photons' overlapping, or combined somehow? Or is it that the 'wave-like' aspect of these photons is so predominant at these frequencies? (I've grappled with this one for a long time.)
Can the properties of the elements be computed from the first principles of particle physics, or do you need to observe the atoms in real life to figure them out? For example, some isotopes are stable and others have a finite half-life. Can you know beforehand or you have to observe the decay? Can you compute exactly the mass of each atom without measuring it? Can you know compute its electronegativity? Etc.
I understand the physical properties of the coin make it so it is an independent event but if I were to run the experiment multiple times the number of times it would be heads after 5 heads would not be an even probability, it would be unlikely since 6 heads in a row is a rare event.
I've been watching a lot of documentaries lately, and I can't figure out how a star that _radiates_ light, collapses and suddenly light can't escape? Doesn't that mean the blackhole has more mass/gravity then the star that created it?
It's difficult to relate the two together and even after hearing every heuristic and every cutesy analogy, I still can't quite wrap my head around what happens to one when I increase the other (and so on).
I just can't grok it.
I can't understand how time would flow differently depending of your speed.
I don't get why C is a constant no matter the referential, for any other object the speed is relative to your referential. I just don't see how those 2 are compatible.
Every time I read an introductory QM book / article, the complex numbers just come out of nowhere and no one bothers to explain how that makes any kind of physical sense.
To pick a couple fo them randomly, understanding amyotrophic lateral sclerosis or alzheimer would be terrific starts.
- What does it mean the universe is expanding
- Bayesian statistics
- How information is stored in magnetic tapes
Electricity is always explained by its effects, but never by its actual nature. I'd like better explanation :-)
2. The tides. The explanation I was given is roughly something like “the tides happen because the moon’s gravity pulls the water toward it, so you have high tide facing the moon. There’s also a high tide on the opposite side of the earth, for subtle reasons that are too complicated for you to understand right now and I don’t have time to get into that.”
The first problem with this explanation is this: gravitational acceleration affects everything equally right? So it’s not just pulling on the water, it’s also pulling on the earth. So why does the water pull away from the earth? Shouldn’t everything be accelerating at the same rate and staying in the same relative positions?
The second problem is that, when viewed correctly, the explanation for why there is a high tide on the opposite side of the earth as the moon is equally simple to why there is a high tide on the same side as the moon.
The resolution to both these problem is this: tides aren’t actually caused by the pull of the moon’s gravity per se, but are actually caused by the difference in the strength of the pull of the moon’s gravity between near and far sides of the earth, since the strength of the moon’s gravitational pull decreases with distance from the moon. The pull on the near water is stronger than the average pull on the earth, which again is stronger than the pull on the far water. So everything becomes stretched out along the earth-moon axis.
3. This one isn’t so much a problem with the explanation itself, more about how it’s framed. I remember hearing about why the sky is blue, and wondering, “ok, more blue light bounces off it than other colours. But isn’t that essentially the same reason why any other blue thing is blue? Why are we making such a big fuss about the sky in particular? ” A much superior motivating question is “why is the sky blue during midday, but red at sunrise / sunset”? I was relieved when I saw this XKCD that I’m not the only one who felt this way:
A guy was walking along the beach and found a lamp. Of course he rubs the lamp, and sure enough a genie appears.
Genie: master of the lamp I can grant you a wish, you may wish for anything.
Guy: Wait, isn't it supposed to be 3 wishes?
Genie: One or nothing, and do not wish for more wishes.
Guy thinks for a while ....
You know I have pretty much everything I need. But I have always wanted to travel to Hawaii. But I get sea sick and am afraid to fly.
Genie: Very well I will take you there.
Guy: No no, if you take me there, I wont be able to come back. And what about next year? Since I only get one wish, I want a bridge built to Hawaii.
Genie: That does not make any sense. Please make a different wish. One that does not involve so much construction.
Guy: hmmmm you know I know, can you explain women?
Genie: So do you want the bridge to be a suspension bridge or truss? and how many lanes ....