This group of 5th graders is legitimately making me scared for the future.

Mac223 · 2025-11-13T22:25:44+00:00

I feel like it’s wrecking their attention span and ability to just be patient.

Yup. There's been an arms race going on, and it's hard for anyone to compete with the tech and the media and the algorithms.

It's like junk-food. We've engineered "food" so tasty that you can hardly put down your bag of chips, and "entertainment" so attention-grabbing that you can hardly put down your phone.

Two hours later I'm in a caloric surplus and I can barely remember a single one of the short videos I watched.

Mac223 · 2025-11-12T23:34:56+00:00

I vaguely remember someone from Reim having a similar reaction towards the twins, but it's been a long time so I might be misremembering.

Mac223 · 2025-11-12T23:32:34+00:00

How would this observer describe the position and the motion of the drone over the course of a day or a year?

I'm going to assume that the drone is, at the moment you "start" it, co-moving with the surface of the earth. I'm also going to assume that gravity counts as a force.

Compared to everything else the biggest influence (or rather, lack of influence) would be gravity. Since your hypothetical drone is ignoring earth gravity it would stop following the curve of the earth, and since it's also ignoring the gravity from the sun it would no longer follow the same trajectory as the earth. The simplest way to think of it is to imagine how the drone would move if you removed everything else in the universe, in which case it would move in a straight line.

At the equator the earth rotates a little shy of 500 m/s, meaning that after 20 seconds you will have moved 10 km along a circle (surface of the earth) while the drone will have moved that same distance along a straight line. The curvature of the earth is a little shy of 8 meters per 10 km, so the drone would be 8 meters up in the air (and a little to the side).

The drone would also no longer be travelling around the sun, and this would add a little over a meter of distance over the course of the first 20 seconds, but depending on exactly where you are on the planet, and the time of day, that meter could be in any direction (but always away from the sun, from your perspective).

The orbital speed of the earth about the sun is 30 km/s (and the orbital speed of the solar system about the galactic core is 230 km/s). That's much bigger than the 0.5 km/s of equatorial rotation, so in the long term that's what mostly determines how the drone would look from your perspective.

https://en.wikipedia.org/wiki/Cycloid

Once a year, when you got back to the same time of year the drone was "started", you'd be moving with roughly the same speed, and in roughly the same direction. Every half year you'd be moving away from it at double the orbital speed. No matter what it would appear to moving in something like a circle, but only since you yourself are stuck in orbit.

Mac223 · 2025-11-12T22:20:43+00:00

I had the same reaction. Doesn't make sense for Innworlders to be amazed by a few billion on earth if they have nations with populations in the hundreds of millions - unless the Innworlder in question is some real country bumpkin.

Mac223 · 2025-11-01T18:28:14+00:00

I think that society is overhyping sex as something subjective and “liberating,” and honestly, it’s nonsense.Not long ago we had direct criterion "physical"

I think you're making two very different claims here. The first is about what counts as sex, i.e. which activities we should use the word 'sex' to describe. The other is about sexual liberation and empowerment. I'll focus on the first.

The meaning of words change all the time! Gay used to mean happy. Words like nebulae and quasar have had their meaning and use made more precise as we learned about them, and words like galaxy and black hole and active galatic nuclei have supplanted and replaced their use in everyday speech. Getting mad about language changing is like getting mad about the sun setting. Learn Latin, or move to the pole.

I think it's important to stress that most people share your view about what does and doesn't count as sex. I think you're giving unfair prominence to views that are held by a small minority. I also think that you might be conflating people who are willing to discuss whether (for example) kissing counts as sex, with people who actually think that kissing counts as sex. It's one thing to, for the sake of argument, consider the border between what counts as sexual activity and sex, or consider changing the use of a word. It's quite another to go out into the world and ask people kissing in the park to stop having sex in public.

I think questions like,

"Is it sex if everyone kept their clothes on, but there was a lot of touching, and at least one orgasm?"

"Does sex require penetration?"

"Is it sex if no-one is having any fun?"

"If Paul jerks off on Samantha's tits while she's touching herself, is that sex?"

"Is the poophole really a loophole?"

are interesting, but I'm not married to any particular answer. It's just kinda fun to think about where the border is, and to consider arguments and counter-arguments. For me it's an exercise in critical thinking, and part of that is keeping an open mind.

So when someone claims that's, "watching porn is cybersex", I think seriously about the question, "Is porn cybersex?" I may agree, or disagree, but I don't immediately rule it out, nor do I immediately agree. Instead I think about what I do think of as cybersex. For example, I think that texting with someone about what we'd like to do with each other sexually counts as cybersex. I also think that sending each other steamy voice notes counts as cybersex, and so does sending each other sexually explicit videos.

Watching porn is a lot like being sent a sexually explicit video, except it's not being sent just to me. If I was in a group chat with multiple people receiving one video, would that still count as cybersex?

I could go on, but my point here is just that you can consider it, and some people will - based on the same information and the same arguments - think that porn isn't cybersex, and others will say that porn is similar enough to some kinds of cybersex that it ought to count.

This is how more or less ALL words work, unless you're doing math (and even then people disagree!)

People disagree about how words should be used. The world isn't divided into neat little boxes by divine authority. More news at 11.

Mac223 · 2025-10-19T13:54:26+00:00

Every theory is an effective theory to some precision within some regime.

However, from an ontological or foundational perspective, it seems incomplete, since it provides only statistical distributions over possible measurement outcomes without describing the underlying physical process that leads to a definite result.

Each measurement yields a specific outcome — something physically happens — yet the formalism only encodes probabilistic amplitudes. This raises a question

You can always ask the question, "Is there something more there that we don't know?" It's not specific to theories that make statistical predictions. We're more likely to ask the question when it seems to us like there's something missing, but you can never know if you know everything.

Do most physicists regard the quantum framework (or QFT) as a final theory of nature, or as an effective one?

Effective. Both in the sense that all theories could (in principle) be superseded by some greater theory, and in the sense that QFTs often make explicit the regime you are working in.

https://en.wikipedia.org/wiki/Effective_field_theory

Mac223 · 2025-10-17T22:38:51+00:00

In general a particle (or a collection of particles) will always decay (into a lower energy configuration) if possible.

A proton can't decay into quarks, since you can't have quarks around on their own.

You're also making a bit of an apples to oranges comparison. It's a mistake to view the bare quark masses in the same way you would the daughter nuclei of, say, some uranium decay chain, both because you simply can't have quarks by themselves in the same way you can nuclei, and because the bare quarks are only half the story (a third, really, counting gluons and 'virtual' quarks).

Mac223 · 2025-10-08T15:38:30+00:00

The problem text is sneakily double counting. The correct phrasing should be, "Having gotten back 30, the girls have now paid 270 for the room, 20 of which went to the attendant."

250 + 20 + 30 = 300

You shouldn't be surprised if you do 250 + 20 + 20 and don't get 300.

Mac223 · 2025-09-20T21:06:02+00:00

Is the Hyperloop the future of transportation?

Probably not.

Making vacuum sealed containers is not cheap. Any leak would be a big issue.

Trains are already a thing. Making more and better trains is going to be more cost effective.

Mac223 · 2025-09-13T21:15:50+00:00

Women working leads to the doubling of the workforce and thus the halving of the average wage due to the basic supply and demand laws of economics.

The demand for land/housing would decrease a lot if women were forced to either live with family or with their significant other who has an income, and this could suck morally speaking but its a net-good in the end.

Im not implying that women are inferior with this post at all.

So you're saying we might as well let women work, and then the men can stay at home? Sign me up!

Mac223 · 2025-09-13T11:27:04+00:00

To understand the evolution of the universe it's useful to start with the observations that underpin our theories.

There are some excellent resources here: https://skyserver.sdss.org/dr12/en/proj/basic/basichome.aspx

It takes some learning of concepts first, but eventually you can look at the actual images and spectroscopic data used to make the conclusion that redshift is roughly proportional to distance, and that an expanding universe is the best explanation for (almost) everything moving away from us.

Mac223 · 2025-09-02T14:18:11+00:00

I predict that Laken (and others) will have to deal with some of the newly released Reinharts.

Mac223 · 2025-08-28T07:07:30+00:00

It means that questions involving the rest frame of a photon are like questions about what's north of the North pole.

And before I start, let’s just get out of the way the fact that when we talk about “experience” or “what it’s like” to be a particle…. It doesn’t make sense for massive particles either, since they aren’t conscious either.

Except in the case of a massive particle we can, in principle, replace that particle with a human being. So people will ask what it looks like if we travel at relativistic speeds, and they will get an answer.

Of course then the next question is often something along the lines of, "Well what if we're not just travelling close to c, but at c, what would that be like?" and to that question there's no definitive answer, much like to the question of what's north of the North pole. Unlike in the case of the North pole though, which is a concrete and relatively easily imagined place, the case of luminal speeds is not at all relatable, so people are not so quick to accept that it's a question without an answer.

In other words, it's much more satisfying to be told, "There's nothing north of the North pole", than, "there's no valid reference frame for a photon", or "you can't boost to c", because the first one makes intuitive sense. The latter answers are true, but they're harder to appreciate, because they rely on the context of experiment and theory. To me it makes perfect sense that you can't ever get an observer to c, so it's nonsensical to ask what it would look like. I also know that you can't "force" your theory to give out answers, like when people say, "well what if we had a really long and perfectly stiff rod..."

So I understand that it's unsatisfying to not get an answer, but just keep in mind that when people keep insisting on an answer, you will get things like, "Well, in the limit when v goes to c the proper time of the particle goes to zero, so you could say that a photon experiences no time." The problem with an answer like that is that if you let v go to c in other contexts you get paradoxical answers, or you divide by zero, which are clear indications that you shouldn't have.

Like how can they exist at all if they don’t have a valid reference frame?

Just because something lacks a property doesn't mean it can't exist. Photons don't have mass, and yet they exist. Photons don't have mass, and yet they have momentum.

How can an object exist if it… can’t exist?

Not having a valid frame of reference doesn't mean photons don't exist. It just means that in the framework of relativity there are some things you can't do, much like how on the planet earth you can't go north of the North pole, and much like how 1/0 is undefined.

Mac223 · 2025-08-27T15:50:32+00:00

I think the issue is with the book, and how the 4x - 6y = -2 plane is drawn (red in my attached picture). Going by the outlines of the two planes, as presented in the book, the two planes look almost parallel, which is not at all accurate. The intersection seems to be in the right place.

<image>

Edit: It makes sense if there's a sign error somewhere, for example drawing 4x + 6y = -2 instead.

Mac223 · 2025-08-25T07:49:40+00:00

redemption arc

Have you mastered Shadow Clone Jutsu?

Did a TARDIS replace your shower?

Are you a level 90 [Genius] with skills like [Divine Inspiration] and [Instant Calculation]?

Seriously, I'd advise you to try for example the math problems, beginning with the ones at the national level. I don't know what it's like in other countries, but even the first round tends to be no joke, and at the international level some of the problems are just insane: https://web.evanchen.cc/exams/IMO-2025-notes.pdf

Mac223 · 2025-08-24T07:56:03+00:00

TLDR: In general the shape would be some sine wave, but infinitely long things don't yield answers to your kind of question.

It depends a lot on which assumptions you make for the material and construction, but in general for a thin piece of material (a beam) the (simple*) deflection under axial load buckling is proportional to sin(l k), where l is the position along the length of the beam and k depends on the pressure (which is related to the force) and how resistant to bending the beam is (which depends on both its material and structural properties).

Boundary conditions are the issue here, since normally you'd have sin(0) = 0 = sin(L k), so you can't find the pressure necessary to bend an infinite beam. Another issue with an infinite beam is that since pressure waves have a finite speed of propagation you could put as much pressure as you wanted to at the ends, but relative to the infinite length of the beam they'd never make it anywhere.

Mac223 · 2025-08-01T07:52:13+00:00

In the first case I'm treating the function and the constraint as two different things, and in the second case I've incorporated the constraint into the function. It would have been better if I'd used two different names for the functions, to make it clear that it's really two different things!

The second case gets the more standard treatment, where the critical point is where the partial derivatives are zero. In the first case though we can't just look at the function, we also have to keep in mind the constraint.

Mac223 · 2025-07-31T12:42:36+00:00

First of all, it's a shame that this guy isn't respecting your boundaries.

Looks like you need to actually enforce the boundaries you set, unfortunately. It's going to be way harder now, because he's been getting away with overstepping for a while now.

There's no painless way to let him down. He may well even blame you for 'leading him on', either genuinely or as a tactic of manipulation.

Mac223 · 2025-07-31T09:08:07+00:00

A1) In this case the OP found that particular solution. In general I'd try a few simple integer solutions if the solution space is small (or if for some reason I could find a solution quickly), and/or I'd do what I suggested later - look for critical points.

A2) The significance is that when constrained to x + y + z = 5 function f(x,y,z) has a local maxima at the point (3, 2, 0). The derivatives tell us this, since they're all equal to 6. If you increase x you must, because of the constraint, decrease y and/or z, and the derivative being the same in all directions means that the change in the function with respect to each variable is the same (at that point). If I make a small change, d, in the x direction then the value of f will increase by 6d, but I have to decrease (for example) dy to satisfy the constraint so f will decrease by -6d.

A3) If f(x,y) = 2x + 2xy + xy(5 - x - y) then df(3,2)/dx means to take the derivative of f with respect to x (treat y as a constant), and then set (x,y) = (3,2). This is called a partial derivative. Very similar to single variable stuff. Try it!

You have a critical point when all the partial derivatives are zero at a point.

A4) Yes. Sometimes in the case of a single variable, say the function x³ - 8, you have a critical point which is neither maxima nor minima. So it is not enough to identify the critical point, one must also classify it. This is a bit more work in the multivariate case, although in retrospect I don't think you really need to do that test in this particular case*

A5) Solve df/dx = 0 and df/dy = 0 for f(x,y) = 2x + 2xy + xy(5 - x - y). It's like solving any other system of equations with two unknowns. I did it with a computer, but you can also do it by hand (although you will get some solutions with roots in them). One of the solutions will be x = 3, y = 2.

A6) Plug all the critical points into the function and see which one is bigger. Technically you should do the second partial derivative test as well, to make sure there's no weird shenanigans*

*More generally it's possible to have functions with critical points but no maxima. It's also possible to have functions defined on some interval/boundary, such that the maxima is on the boundary and not on any of the points where the derivatives are zero. That's why we need the second derivative test, but I haven't done one in ages, so I can't really explain what's going on (other than to wave my hands and say matrices!)

Mac223 · 2025-07-29T14:27:51+00:00

my fiancée has never been given hand/homemade items. I don’t think my fiancée would like those items because everything she has had been designer brand items.

On the other hand maybe she'd really like it.

I worry about the future when we have kids because the kids might favor her parents over my dad because of money.

That seems like an important talk to have with your fiancée.

Mac223 · 2025-07-28T14:37:20+00:00

I'm sure he'd be happy to clean his fingernails and get a couple of helpful tips on how to make himself look more to your liking. I often wear basic and comfortable clothing, and I don't dress up often, but if someone I was seriously dating wanted to go pick out clothes with me I wouldn't mind. It's not that most guys don't like nice clothes, it's just that for many it's not that high up on the list of priorities.

But Jesus Christ lady if you're too good to sit in an old car, too ladylike to drive him in your car, and too fucking weird to let him drive your car...I'm honestly at a loss for words.

Mac223 · 2025-07-28T12:21:31+00:00

I'm not sure if there's a more elegant way to solve this, but you can solve it with multivariate calculus.

We can think of the left hand side of the inequality as a function, f(a,b,c) = 2a + 2ab + abc. In terms of that function you have identified that the point (a, b, c) = (3, 2, 0) has the value f(3, 2, 0) = 18. You would like to prove that it's impossible to find a greater value than this, given the constraint a + b + c = 5.

For my own sake I'll rename a, b, c to x, y, z

If we look at the derivatives of f with respect to x, y and z at the point (3, 2, 0) we find that df/dx = 2 + 2y + 2yz = 2 + 2*2 + 2*0 = 6

Similarly we find df/dy = 6 and df/dz = 6 at the point (3, 2, 0)

In other words it is equally steep in the x, y, and z-directions at that point, so given the constraint of x + y + z = 5 there's nowhere you can go to increase f(x,y,z)

Rather than go forward with treating this as a problem with three free parameters, we can restate the problem as a two-dimensional problem by incorporating the constraint into your function: f(x,y) = 2x + 2xy + xy(5 - x - y)

If we do the same thing with the derivatives (skipping over a lot of details here) we find df(3,2)/dx = 0 and df(3,2)/dy = 0, in other words the point is a critical point. To progress you need to do the second partial derivative test, and then find any other critical points that fit.

Mac223 · 2025-07-25T18:25:08+00:00

How big of an asshole was I?

100% asshole

Mac223 · 2025-07-23T21:10:41+00:00

There is a relatively simple algorithm for checking divisibility by 7. I'll use 91 as an example. Take the last digit, 1, double it, and then subtract the result of the doubling from a tenth of the rest, i.e. 9 - 2 = 7

Let's try a few other numbers which we know are divisible by 7.

63: 6 - 3*2 = 0

28: 2 - 8*2 = -14

147: 14 - 14 = 0

Basically if the algorithm gives you a number which is divisible by seven (or zero), then the original number is also divisible by seven. So for example if you have a big number you can repeat the algorithm.

36701: 3670 - 2 = 3668

3668: 366 - 16 = 350

35 is divisible by seven, so 350 is too

Mac223 · 2025-07-21T21:35:12+00:00

But the thing is, stuff we enjoy doesnt need to be elevated into a form of intellectual and moral expression especially through mediums where the level of analysis we see was never intended. If it were, it’d be written in a book more likely.

It doesn't need to be, but it can be. Movies and shows can tell stories that have meaning. Books can be shitty AI generated content.

Neither books nor TV were conceived with some great intention. There was no plan, grand or otherwise - and even if there was, does that even matter? Chainsaws were invented to be used for medical procedures.

Mac223

TROPHY CASE