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OK, I had a hard time coming up with a single sentence title, so please bear with me.

Let's assume I have a computer with a perfect random number generator. I want to draw from a (electronic) deck of cards that have been shuffled. I can see two distinct algorithms to accomplish this:

1. Fill a list with the 52 cards in random order, and then pull cards from the list in sequence. That is, defining the (random) sequence of cards before getting them. This is analogous to flipping over cards from a the top of a well-shuffled deck.

2. Generate a random card from the set that hasn't been selected yet. In other words, you don't keep track of what card is going to come up next, you do a random select each time.

Programattically I can see advantages to both systems, but I'm wondering if there's any mathematical or statistical difference between them.

tl;dr don't bother. This is too abstracted and nuanced. That is okay to skip.

I like to understand the abstract scope of engineering. This is way beyond the simple surface level, with pics below to illustrate my point.

With electric guitar pickups, the complexity of field shaping and design control over the sensor seems like a place where optimising the profitable manufacturability of the final product remains the primary constraint with little deviation.

I struggle to qualify and quantify my intuitive hunch that there is a whole lot more potential to engineer something new and better within the realm of modern manufacturing. I don't know the principal questions I should ask or what might disprove my ideas from the get go.

• Most transformers shape the magnetic field far more than guitar pickups.
• a guitar pickup appears to be more of a two dimensional sensor that picks up the motion of a ferromagnetic string in the two primary directions of motion
• there are more complex harmonic motions present than a pickup can register in two dimensions
• the coil and slugs of a pickup are surrounded by a single large winding, yet the strings each have very different frequencies
• it is now possible to make a powdered ferrite core of nearly any shape and frequency
• the traditional pickup has little effective shaping of the magnetic field path
• guitar pickups are not optimised to a point where they are readily used elsewhere in other sensory applications and devices as economy of scale should dictate in an open and manipulation free market... I don't think they are anyways
• what might be the result if a 270° toroidal powdered core were designed and shaped for each string while tailoring the copper winding and ferrite for each string's mean frequency and shielding each of these
• would a chord segment gap in a toroidal core pick up more 3d motion from the string
• what effect would a primary and secondary winding wound in the opposite dot notation direction have on the pickup of more complex harmonics and motion
• why does none of this matter due to the filtering of LCR and the noise floor or other aspects

Like here is the basic range of commercial products:

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The typical schematic of operation:

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Basic construction:

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This is a typically low noise toroidal transformer that has been around for ages:

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Now I need you to abstract this concept with me a little bit. Imagine if a small toroidal core was below each string and offset towards the neck or bridge so that they will fit. Nothing would stick out or surround the string. The 270° is not a radius cut like a pie. Instead it is a chord and removed segment:

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There are totally random pics from DDG that are somewhat illustrative in abstract:

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These are just some random powdered core ferrites that illustrate how these can be formed into any shape now:

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I usually avoid anything audiophile related because it draws out pseudo science nonsense like crazy, but at the center of this question is really a desire for a deeper understanding of sensors and magnetics that have much broader applications in precise motion control and sensors for a range of equipment.

In a higher level of abstraction, I'm also really asking when and where does this subject become the realm of the illusive bearded nude virgin demigods that get enslaved to corpo NDA masters from birth. ^.5/s

I'm researching all of this, and it seems cats are the main(?) host for T. gondii. And yet it can infect humans as well. As far as I know, it does (sometimes) virtually nothing except either maybe give you schizophrenia or make you a "Risk-taking Asshole" for lack of a better term. What is even the purpose of doing this to infected humans??? WHY??? What kind of parasite infects a human with the only real side effect of "I'm just gonna make you gamble a lot and give you road rage."

Obviously there's other, more serious side effects. But I truly don't understand what its goals are once it comes into contact with humans. Are we just another body to them? A scenario of "Oh well im in this human now so... Guess I better get comfy or whatever."

Keep in mind I'm aware the Parasite isn't like a person, it doesn't just "do stuff" the way we humans do. It can't really think. My confusion stems from why it even bothers evolving just enough to be able to infect humans in the first place. Why doesn't it just stick with cats? And when it does infect humans, why does it just- not do anything half the time? It's like it only infects people Internally just to mildly inconvenience them.

I've noticed something interesting that I cant get an answer to online. Whenever I leave out watermelon in my house (After eating it of course. I cut slices from the melon so what gets left behind is the rind), it attracts lots of gnats and flies without failure. After cutting and eating a Yellow Watermelon for the first time and then leaving it out, There wasn't a single fly that cared for it, it was never swarmed or landed on or fed upon. it just sat there for a day or so before I finally threw it out.

Why is this?? Repeating this same scenario always gives me the same output. The flies aren't attracted to the Yellow Melon, Why?

I know animals can have limbs surgically replanted and still work. But can the same be said about plants? Could I cleanly cut down a tree, then stick it back on, and have it still grow into itself?

I couldn't find anywhere that would tell me what kind of motor is usually used there. And I don't know enough about motors to be like... well of course it's this kind... But once I know what it is... how does it work? Like different adjustable bases move different intervals for a single push of the remote button (at least according to my wife). So that got me thinking, what controls the minimum interval of difference between two positions the motor will support? I don't hear clicks, so I don't think it is a ratchet type thing which would have a clear min interval. Yet, if you unplug it, it doesn't just go flat. So there must be some sort of passive hold mechanism of some type...

Sometimes, when I'm really cold, it can take over an hour to warm me up, even with a heating blanket. The quickest solution, a hot shower, feels really inefficient with all the heat going down the drain.

That got me thinking about microwaves. They heat food (partly) from the inside, contrary to simple infrared radiation.

Could we safely do that with people?

I found a Reddit thread where a non-lethal weapon and people getting eye damage because they stayed too long in front of a radar dish.

Could some sort of device be made that would warm specific areas (say, a hand or a leg) without endangering sensitive areas like the eyes?

Would it actually warm someone up from the inside? Would it be possible to make it safe?

Would it present advantages in cases of hypothermia, compared to heated IV fluids?

I find fractals extremely fascinating and way, way, way out of my depth. One example being the Barnsley Fern, which I find so cool. It feels a bit like someone cracked a little piece of the Matrix code.

But is there anything really significant about the fact that it looks like a fern from a botanical/mathematical perspective? Do the two connect in any real way? Can we somehow find the math genetically or learn something about the mathematical properties of other leaves, for example? How "real" is it?

If I could make an oak leaf from fractals, would it advance mathematics and/or botany or would it be equivalent to creating a cartoon using Geogebra (nice to look at, but basically meaningless)?

In other words, is there any individual cell that can decide between two or more options, or all they all solely chemical and mechanical reactions without any self-determination at all?

Like fossil fuels come from organic matter that grew because of the sun. Is there any form of energy on that cannot be traced back to the sun in some way?

Like the title says: when you see "heat rising" (the wavy/blurry area above a heat source), what are you actually seeing?

Bonus question: How does that cast a shadow? I noticed when I was opening my air fryer, I could see the shadow of the heat rising but, looking at the hot basket itself, couldn't see it.

In the color lines of a spectrograph and what seems to be an area with a certain color, zooming in shows that this color is delicately split in half by a black vertical hairline, on one side it's the emission of photons of color by a hydrogen atom with a spin up electron, on the other it seems to be the same color but it's a spin down electron.

Whenever I hear that gap mentioned, 1/137 is invoked, but I'm not sure precisely what that means, and I'm visualizing that the color of the spectral emission can be divided or deconstructed into a total of 137 vertical lines, and the one in the middle is black.

Maybe it represents 1/137 of a photon's wavelength at a certain color?

There is a tendency for real doctors with backing from Academia or whoever's in charge of deciding how you science to just plain getting it wrong and not realizing it for a long time.

Homeopathy is a good example of this, as it appeared to get great results when it was created during the Bubonic Plague and had such staying power to the point that in the 1800's it was considered a legitimate and mainstream field of medical practice.

Now today we know Homeopathy is nonsense... Remembers New Age Healing is still a thing Okay, those of us with sense know homeopathy is garbage. With the only reason it was getting such wonderful results was because the state of medicine for a long period of time in human history was so god awful that not getting any treatment at all was actually the smarter idea. Since Homeopathy is basically just "No medicine at all", that's exactly what was happening with its success.

Incidentally this is also why the Christian Science movement (Which was neither Christian nor Science) had so many people behind it, people were genuinely living longer from it because it required people to stop smoking at a time when no one knew smoking killed you.

Anyhow. With that in mind, I want to know if there's a case where the exact opposite happened.

Where Scientists got together on a subject, said "Wow, only an idiot would believe this. This clearly does not work, can not work, and is totally impossible."

Only for someone to turn around, throw down research proving that there was no pseudo in this proposed pseudoscience with their finest "Ya know I had to do it 'em" face.

The closest I can think of is how people believed that Germ Theory, the idea that tiny invisible creatures were making us all sick, were the ramblings of a mad man. But that was more a refusal to look at evidence, not having evidence that said "No" that was replaced by better evidence that said "Disregard that, the answer is actually Yes"

Can anyone who sciences for a living instead of merely reading science articles as a hobby and understanding basically only a quarter of them at best tell me if something like that has happened?

Thank you, have a nice day.

What if I am just imagining the high pitch sound in my mind whenever I hear about or think of tinnitus just like how someone tells you to imagine a whale and you form a mental image of a whale? I don't pay attention to the noise while I'm busy doing stuff but once I think about it, it is as hard to stop noticing it similar to being told to breathe manually, and it gets very annoying after some time. Is it what tinnitus really is?

We've pretty much completely discounted astrology as having any meaningful impact on a person's personality. But what about the seasons of the year, and the weather that comes with them? The stars position in the sky are an indication of the seasons on earth. Right? Wouldn't a baby that is born into a world of sunshine and warmth have a different early development than one born into the cold and darkness of winter? Has any research been done on the impacts of a baby's environmental conditions on their personality?

I know that lions can be scared away when they see humans approaching without fear, but what if they're ambushed? How about a tiger, or a polar bear? If I manage to sneak up on one of these apex predators, and jump out, screaming, and running at it, will it run? Or will it just turn around and kill me? I guess I'm wondering if apex predators have a fight or flight reflex, and how strong it is if they do. Do they tend to resort to fighting more often if they're the baddest tiger in the jungle vs the runt of the litter? Do they quickly assess the threat and respond accordingly, or does a flight instinct kick in and send them running?

A few minutes ago I suddenly woke up , I didn't sleep well

At the beginning everything was normal , then I blinked and ...

The lighting suddenly became more yellow (and unnatural) and the closet I was looking at turned into a frightening and shocking appearance (the closet itself, it was vandalized in a way that I can't even remember to describe). I remained in shock for three or four seconds, then I found myself closing my eyes tightly ( it was an involuntary reaction ), and when I opened my eyes again, everything returned to normal.

This is the first time in my life that this has happened to me

So ... any scientific explanation?

Thanks in advance

Or in other words which forces keep electrons in orbitals and prevent it from flying away or crashing into the nucleus according to modern understanding?

Could someone recommend examples of high-fidelity, best-practices Western Blots from Open Access Papers? I would like to use these examples to see what kind of distortions or corruption might occur to these images when they are reproduced or archived in various ways.

So every time we get bread it comes in a stretchy bag. However, once we pull it out of the freezer later the bag is noticeably more crinkly and brittle. Anyone know why this is? I can't seem to find an answer to this phenomenon anywhere.

Let's say the roofs are all red, how big does it have to be to be visible as a little red dot?

Hi,

I found this scientific paper that I believe is very well supported and is for me the most satisfying new cosmological development I ever read.

Cosmological Particle Production: A Review (2021 December 7 // @ arXiv...) https://arxiv.org/pdf/2112.02444.pdf

... the way I read it, it provides an alternative explanation for the cosmological microwave background (CMB) and an alternative for the Big Bang.

I am simply on a quest to find an effective non-distillation method for purifying isopropyl alcohol used for rinsing resin 3D prints.

I have seen some elaborate systems for curing and then filtering resin that is suspended in the isopropyl by running it through standard carbon water filters. That just seems a bit over-complex and does a poor job of removing dyes. In some cases, the filters are not fine enough and the isopropyl will eventually get "sticky".

It seems to me that a finer filtration system would work much better. Carbon and celite should catch most of the monomers and oligomers, but I am not sure about the photoinitiators and other additives.

Distillation is obviously the best method for purity, but there may be a worse cleanup and a higher fire hazard risk.

Are there better materials that I could use for filtering besides celite and carbon? IPA is tiny compared to the rest of the molecules I am dealing with so filtration seems viable.

(I should note that I would bulk develop the used IPA in clear plastic containers in the sun for a day or two first.)

I'm referring to the human race evolving in the African continent and then migrating to the rest of the world.

Evolving in Europe made people light skinned to account for the reduction in sunlight exposure, are there any other traits which other ethnicities developed to adapt to their new environment? Or are the diifferent traits in different ethnicities just stuff that developed by chance and got somehow reinforced because of the isolation between populations?

This question came to my mind first thinking about "Asian eyes", do they serve any "purpose"?

There are many other bee species that can sting Humans and survive, but the European honeybee has a barbed stinger, so it cannot remove the stinger once it's stung. In attempting to remove the stinger the bee will rupture its lower abdomen and then die.

Why? What is the evolutionary advantage to that?

We often talk about the climate impact based on greenhouse gases, but extracting fuel from the ground and using it in exothermal processes of course also releases energy as heat.

This is mostly¹ in contrast with renewables, which make use of energy that's not long-term contained to begin with, so would end up as heat in our atmosphere anyways.

So, my question is: Does the amount of energy released by non-renewables have any notable impact on our global temperature? Or would it easily radiate into space, if we solved the greenhouse gas problem?

---

¹) In the case of solar, putting up black surfaces does mean that less sunlight gets reflected, so more heat ultimately gets trapped in our atmosphere. There's probably other such cases, too.

Say a dissolvable spring is compressed with a bolt and nut that do not melt in a sulfuric acid solution. The spring has quite a bit of potential energy at this point since it is compressed. Assuming the spring dissolves perfectly (no breakage, just complete disintegration), what happens to the potential energy of the spring?

Famously, Oppenheimer and co worked out how close a nuclear bomb test would be to causing a chain reaction of nitrogen fusion in the atmosphere. They made a lot of worst-case-scenario assumptions and still came to the conclusion that no, a nuclear bomb test wouldn’t scour the surface of the world.

But let’s say the atmosphere was twice as dense as it is. Or ten times as dense. At what point would that calculation turn very, very scary?

Obligatory xkcd

Edit: man, seriously, most of the people ‘answering’ this question didn’t even read it.

Okay, so I know this might be a bit hyperspecific, but I don't know where else to ask it. I'm working through a microbiology lecture, and the professor says the the B strain of E. coli has a tRNA suppressor that allows it to transcribe phage genes that have any nonsense mutation. That seemed a bit vague, so I decided to look it up. But the only thing I can find that's even remotely similar is that that strain doesn't express T7 RNA polymerase, which doesn't seem terribly helpful. Is there anything like this in that particular strain? It seems like a load of bs to me that a bacterium should just be able to ignore any stop codon.

Edit: My prof might have been referring specifically to an amber mutation. So, just one stop codon. Seems my resources are just poorly worded.

Asking because while I see that paint hardeners exist in the USA, there doesn't seem to be anything similar in my country (Brazil)

What could I use as a substitute to harden paints? Are there any catalysts or powders that would work?

Google and DDG always show sites/articles about epoxy resins whenever I search for "acrylic hardener", is it safe to assume that catalysts for epoxy, like polyamide, will work with acrylics?

Now that late spring/early summer is upon us, there's increasingly more headlines about less rain in various places (recent floods notwithstanding). I'm assuming that's because water is evaporating and not returning to those places, but where is it going?

Is it arriving, now, in these bursty flash floods? Is it staying longer in the atmosphere and moving to new locations? Is more of it just staying in the atmosphere period?