Anonymous at Thu, 13 Feb 2025 19:43:29 UTC No. 16585036

>>16584917
Any anon got the PDFs of the Trivium by Verbitsky?

Anonymous at Fri, 14 Feb 2025 00:07:02 UTC No. 16585296

>>16583878
I'm this anon, waiting on the other kind anon to help

Anonymous at Fri, 14 Feb 2025 03:09:27 UTC No. 16585401

Is there a specific nerve i can easily sever that will make me permanently lose my ability to speak?

Anonymous at Fri, 14 Feb 2025 13:09:56 UTC No. 16585716

i would like to do a relatively pure psilocybin/psilocin extraction but every tek i found online leads to an impure mush. where can i find a good, reliable method?

Anonymous at Fri, 14 Feb 2025 13:48:20 UTC No. 16585730

>>16585716
What about doing own research? I can only tell you where to order pure 4-ho-det.

Anonymous at Fri, 14 Feb 2025 13:50:26 UTC No. 16585732

>>16585716
You don't want to google, but duckduckgo.
Also shroomery and DMT-nexus

Anonymous at Fri, 14 Feb 2025 14:59:02 UTC No. 16585756

>>16585730
chemistry has a very high entry level. you need many years before you can look at a compound's skeletal structure and be able to tell what you can do with it
>>16585732
neither of those have a working tek nor even attempt to write about pure product extraction

Anonymous at Fri, 14 Feb 2025 15:08:45 UTC No. 16585761

>>16585756
I have grade school chemistry and I already know I just need to look out at solubility in solvent I want to use, possibly working with more solvents, some to dissolve trash and some to dissolve substance, then get only what dissolved substance separated from what dissolved trash, and evaporate only solvent which has non-trash in it. Maybe you need to get substance from one solvent to another, by mixing something else into one of solvents, to push out your desired thing to your solvent. You can find solubility sheets online.

Or just get some info on column chromatography.

Anonymous at Fri, 14 Feb 2025 15:10:02 UTC No. 16585762

>>16585761
I forgot to mention, sometimes you can mix in substance, so you'll create perciprate of something and separate it in filter.

They learned me all this in grade school.

Anonymous at Fri, 14 Feb 2025 15:15:02 UTC No. 16585766

>>16585756
If you really have that much excess mushrooms, rent a supercritical CO2 extractor.

Anonymous at Fri, 14 Feb 2025 17:18:19 UTC No. 16585855

>>16585296
>>16583878
The first thing you tried does not quite work, because unions are different from intersections.
You take [math]y \in f(\cup_\alpha A_\alpha)[/math], so there is some [math]x \in X[/math] such that [math]y=f(x)[/math], as you say, but now you only know that [math]x \in \cup_\alpha A_\alpha[/math], so you don't know which [math]A_\alpha[/math] [math]x[/math] is in.
Previously, you knew that [math]x\in \cap_\alpha A_\alpha[/math], so that for each [math]\alpha[/math], [math]x \in A_\alpha[/math], but now, you only know that it's in one of the [math]A_\alpha[/math], as opposed to being in all at the same time.
So, you get some particular [math]\beta[/math] with [math]x \in A_\beta[/math].
Then of course [math]y=f(x) \in f(A_\beta)[/math], and since [math]\beta[/math] is one of the [math]\alpha[/math]'s, you also get that [math]y \in \cup_\alpha f(A_\alpha)[/math], which shows that [math]f(\cup_\alpha A_\alpha) \subseteq \cup_\alpha f(A_\alpha)[/math].
To show that in fact [math]f(\cup_\alpha A_\alpha) = \cup_\alpha f(A_\alpha)[/math], you'd still need to show the other inclusion.

For the proof that [math]\cap_\alpha f(A_\alpha) \not \subseteq f(\cap_\alpha A_\alpha)[/math] in general, you'd have to find a counterexample.
That is, sets [math]A_\alpha[/math] for some indices [math]\alpha[/math] for which the inclusion does not hold.
This can be very simple (take, for example, [math]f(x)=x^2[/math]).

Anonymous at Fri, 14 Feb 2025 17:23:43 UTC No. 16585860

>>16585401
You seem like Hamas terrorist trying to damage hostage.

Anonymous at Fri, 14 Feb 2025 17:33:45 UTC No. 16585867

If a wheel is rolling like this (radius=r) with a given velocity, what is the velocity of a point on the edge of the wheel as a function of time?

Anonymous at Fri, 14 Feb 2025 18:24:39 UTC No. 16585895

>>16585761
>>16585762
anon, bro, bruh, my brother in faith
it's not about solubility. there's hundreds of these teks out there. i want to Hofmann style purify it. i want crystals or powder, not grey mush and for this i need either a thorough guide, advanced skill in chemistry to figure things on my own or PM someone like NileRed and hope that he wants to say
the best i found was A/B extraction, using polar/non-polar solvents but the effect was still mush
>>16585766
i want to remove all the stuff that gives the nauseous/toxic effects of eating raw mushrooms

Anonymous at Fri, 14 Feb 2025 18:25:54 UTC No. 16585896

>>16585867
[eqn]
r(t)=(vt+r\sin(t))\hat{\textbf{x}}+(r\cos t+r)\hat{\textbf{y}}
[/eqn]
The [math]r\sin(t)[/math] and [math]r\cos t[/math] terms come straight from a polar transformation; we know it's a circle. We determine which axis gets which trig function via some thinking and arbitrary start conditions. I started at the top of the wheel, and thought it'd spin rightwards, so y has start at its maximum (cosine), and x has to start at 0 and increase (sine). We then need to add a flat amount to account for the wheel's movement to the x. We're looking for distance, so just multiply the velocity by the time. For the y axis, we need a constant offset so that it doesn't dip below the ground, but rather the minimum is zero. So just add r. Of course, you could define your origin at the center of the wheel to change this.
This is a graph to show you it works. Just 'play' the time value.
https://www.desmos.com/calculator/kp60qpxeqj

Anonymous at Fri, 14 Feb 2025 18:28:11 UTC No. 16585897

Let
[math]A = \begin{pmatrix}8 & -21\\ 2 & -5\end{pmatrix}\;,\; v = \begin{pmatrix}\pi^e \\ e^\pi\end{pmatrix}
[/math]
How can I calculate the limit of [math]A^nv[/math] as [math]n\to \infty[/math]? This matrix is not diagonazible

Anonymous at Fri, 14 Feb 2025 18:32:44 UTC No. 16585898

>>16585860
No it's just self harm

Anonymous at Fri, 14 Feb 2025 18:34:56 UTC No. 16585900

>>16585895
I eat dried mushrooms and never get nausea. You won't get nausea from A/B extract for sure... But you can look at some RC's vendor site and just order 4-HO-DET, and you'll have clean powder, if you just want it for personal use it's simple way to have a nice, clean trip.

Anonymous at Fri, 14 Feb 2025 18:43:45 UTC No. 16585906

>>16585897
[eqn]
A^n=\begin{pmatrix}
7(2^n)-6&-21(2^n-1)\\2(2^n-1)&7-3(2^{n+1})
\end{pmatrix}\\
A^nv=[7(2^n)-6]\pi^e-21(2^n-1)e^\pi+2(2^n-1)\pi^e+[7-3(2^{n+1})]e^\pi\\
\lim_{n\rightarrow\infty}A^nv=\lim_{n\rightarrow\infty}[7(2^n)-6]\pi^e-21(2^n-1)e^\pi+2(2^n-1)\pi^e+[7-3(2^{n+1})]e^\pi=-\infty
[/eqn]
The last step is just from the n+1 term dominating.

Anonymous at Fri, 14 Feb 2025 19:41:22 UTC No. 16585961

So the spooky part of entanglement is that the wave function collapses at a distance? How do we know it does?

Anonymous at Fri, 14 Feb 2025 19:48:52 UTC No. 16585972

>>16585961
Do you really think, that you can affect one particle and it has effect on another?

Anonymous at Fri, 14 Feb 2025 19:58:19 UTC No. 16585977

>>16585961
Do you realize that wavefunction doesn't collapse anywhere but in your head?

Anonymous at Fri, 14 Feb 2025 20:05:24 UTC No. 16585985

>>16585972
That is what some explanations of QE say.
>>16585977
I thought it meant the wave state of wave particle duality transitions to the particle state.

Anonymous at Fri, 14 Feb 2025 20:12:21 UTC No. 16585992

>>16585985
It means you placed sensor somewhere which affected dynamics of whole situation.

Anonymous at Fri, 14 Feb 2025 20:14:09 UTC No. 16585995

>>16585900
why pay extra when i have jars full of dried shrooms

Anonymous at Fri, 14 Feb 2025 20:16:18 UTC No. 16585998

>>16585995
You're gifted,...

Admire the universe for giving you such good supply.

Also, tea is sufficient for having little to no side effects.

Anonymous at Fri, 14 Feb 2025 23:02:08 UTC No. 16586121

>>16585998
tea is not convenient to carry around

Anonymous at Sat, 15 Feb 2025 01:03:58 UTC No. 16586213

>>16585897
Look up jordan canonical form, use chatgpt to help

Anonymous at Sat, 15 Feb 2025 06:32:35 UTC No. 16586380

>>16586121
A/B extraction can reach 95% purity, at that point you won't have side effect either, there's lot of articles if you duck duck go it.

Anonymous at Sat, 15 Feb 2025 12:36:28 UTC No. 16586575

>>16586213
I can decompose it as [math]\begin{pmatrix}3&7 \\ 1&2\end{pmatrix}\begin{pmatrix}1&0\\0&2\end{pmatrix}^n\begin{pmatrix}-2&7 \\ 1&-3\end{pmatrix}[/math] but it diverges apparently, or I'm doing something wrong

Anonymous at Sat, 15 Feb 2025 13:03:37 UTC No. 16586594

>>16584917
>asian AI slop
White women rule the world

Anonymous at Sat, 15 Feb 2025 15:50:01 UTC No. 16586792

Why is Steven hawking famous for unverified predictions?

Anonymous at Sat, 15 Feb 2025 16:06:52 UTC No. 16586804

>>16586575
the other guy already mentioned it diverges, what's the confusion?

🗑️ Anonymous at Sat, 15 Feb 2025 16:11:43 UTC No. 16586809

>>16586575
You're saying the eigenvalues of the matrix are 1 and 2? Doesn't that mean the matrix isn't singular? Doesn't your form mean it's diagonalizable? The middle of the matrix J should be something like [ 2 1 ; 0 2 ] or [ 1 1 ; 0 1] if it's singular

Anonymous at Sat, 15 Feb 2025 16:11:52 UTC No. 16586810

>>16584917
serious question, if this was your daughter, who would you finally give her away to?

Anonymous at Sat, 15 Feb 2025 16:14:01 UTC No. 16586811

>>16586804
The statement of the question read as follows:
>Find the equation of the line for which the sequence [math]A^nv[/math] tends to.
I figure that'd be the span of the resulting vector.

Anonymous at Sat, 15 Feb 2025 16:21:01 UTC No. 16586815

>>16586811
Assuming >>16585906 has the correct A^n, then multiply it by your vector v, then you'll get a vector, not a number

Anonymous at Sat, 15 Feb 2025 16:28:34 UTC No. 16586820

>>16586815
btw, since n is going to infinity, then A^n is basically 2^n times the matrix [ 7 -21 ; 2 -6 ]. Multiply this by v to get your line, cause the vector then gets multiplied by 2^n each time

The question wants you to know that when you go to infinity, small constants can be ignored, kinda like how (x^2 + 1)/x^3 is basically 1/x as x goes to infinity

Anonymous at Sat, 15 Feb 2025 18:09:26 UTC No. 16586928

I just noticed a NOAA dataset I'm using is going 503 on their website. I'm guessing the Trump admin is shutting it down. Are there any efforts backing up this stuff in oversea servers outside his reach? Not a fed btw.

Anonymous at Sat, 15 Feb 2025 18:59:24 UTC No. 16586976

>>16585036
They are on the archive:
>>16493957
>>16493959
https://i.warosu.org/data/sci/img/0164/75/1732621975485306.pdf
https://i.warosu.org/data/sci/img/0164/75/1732622117192313.pdf

Anonymous at Sat, 15 Feb 2025 19:40:34 UTC No. 16587043

Given the points [math]v_0=(0,0,0,0)\,,\,v_1=(1,1,1,1)\,,\,v_2=(-1,1,-1,1)\,,\,v_3=(2,1,-2,-1)[/math], how do I calculate the surface area of the tetrahedron which take these points as vertices?

Anonymous at Sat, 15 Feb 2025 19:46:47 UTC No. 16587056

>>16587043
You've got too many dimensions.

Anonymous at Sat, 15 Feb 2025 19:47:29 UTC No. 16587058

>>16587056
I'm aware of that

Anonymous at Sat, 15 Feb 2025 20:05:54 UTC No. 16587090

>>16587058
Well, context would go a long way. Without any if you must answer I'd personally just throw out the first coordinate, assuming it's time, then go from there using Heron's formula.
I'd just write "Too many dimensions" if it was on a test and ask the prof though.

Anonymous at Sat, 15 Feb 2025 20:13:06 UTC No. 16587099

>>16587090
There's no further context to the question, it's literally just that. Months past the exam, I still don't know the answer

Anonymous at Sat, 15 Feb 2025 20:30:52 UTC No. 16587125

>>16587043
Just add the surface areas of each side together.

[eqn]A = \frac{1}{2} \left(\|v_1 \times v_2\| + \|v_2 \times v_3 \| + \|v_3 \times v_1\| + \|(v_2 - v_1) \times (v_3 - v_1) \| \right) [/eqn]

Anonymous at Sat, 15 Feb 2025 20:31:57 UTC No. 16587128

>>16587125
It's in 4 dimensions. There's no cross product

Anonymous at Sat, 15 Feb 2025 20:33:04 UTC No. 16587131

>>16587128
Then take the wedge product.

Anonymous at Sat, 15 Feb 2025 20:33:37 UTC No. 16587132

>>16587043
>>16587125
Just use Pythagoras, holy shit.

Anonymous at Sat, 15 Feb 2025 20:39:50 UTC No. 16587141

>>16587043
>calculate each side length from the distance formula
>three side lengths that form a valid triangle (these all do) uniquely determine that triangle, and thus that triangle's area
>add all the areas together
???

Anonymous at Sat, 15 Feb 2025 21:45:33 UTC No. 16587242

>>16586928
it's gonna be a hilarious disaster next hurricane season when we are suddenly using 1910 tech for monitoring storms.

Anonymous at Sun, 16 Feb 2025 01:44:22 UTC No. 16587459

>>16586928
https://www.reddit.com/r/meteorology/comments/1iihl5s/backups_for_nws_and_noaa_data/

Anonymous at Sun, 16 Feb 2025 03:05:54 UTC No. 16587528

>>16585401
leave that poor dear kitty cat alone

Anonymous at Sun, 16 Feb 2025 03:15:26 UTC No. 16587535

>>16585867
the two velocities may be equal

Anonymous at Sun, 16 Feb 2025 03:29:48 UTC No. 16587545

>>16585897

Anonymous at Sun, 16 Feb 2025 03:39:03 UTC No. 16587548

>>16585906
(A^n).v is a vector
not a scalar
Jesus Christ

Anonymous at Sun, 16 Feb 2025 05:07:36 UTC No. 16587593

>>16586820
this was meant for >>16586811

Anonymous at Sun, 16 Feb 2025 06:30:45 UTC No. 16587636

>>16586811
It's the span of the limit of the unit vectors (A^n)v/||(A^n)v||

Anonymous at Sun, 16 Feb 2025 15:03:22 UTC No. 16587948

>>16585762
> They learned me all this in grade school.
They learned you in school? Why would they do that ? What is , or was, so interesting about you that intrigued them enough to want to learn you?

Anonymous at Sun, 16 Feb 2025 15:05:14 UTC No. 16587949

>>16587948
https://en.wiktionary.org/wiki/learn#Etymology_2
as ESL as it sounds, he's not actually wrong to use it that way

Anonymous at Sun, 16 Feb 2025 16:08:09 UTC No. 16588005

Why does an object's mass increase when it's moving faster? And if movement is always relative, then is the corollary of this that mass is also relative? I probably sound like a retard but this is for stupid questions and stupid questions I will ask.

Anonymous at Sun, 16 Feb 2025 16:21:13 UTC No. 16588027

>>16586380
do you know the stability of pure psilocin? will it be stable enough to "carry around"? is it something that can be easily stored?

maybe look into getting 4-AcO-DMT, which is converted into psilocin in the liver, just like psilocybin

Anonymous at Sun, 16 Feb 2025 16:22:29 UTC No. 16588029

>>16586121
>>16588027
wrong reply. im retarded

Anonymous at Sun, 16 Feb 2025 16:45:34 UTC No. 16588050

>>16588027
psilocybin is stable, psilocin is not. this makes it that much more inconvenient to extract and purify

Anonymous at Sun, 16 Feb 2025 20:12:02 UTC No. 16588386

>>16588005
In relativity there are two different quantities that have the term 'mass' in them. There is the rest mass (which never changes) and the inertial mass. In Newtonian Mechanics they are the same quantity, that is not true in relativity. It is the inertial mass (often called the relativistic mass or relativistic energy) that depends on velocity (and the observer, so yes, the inertial mass is also relative). Since the inertial mass increases as you go faster, the harder it is to accelerate an object the close it gets to light speed.

Anonymous at Sun, 16 Feb 2025 21:06:25 UTC No. 16588444

>>16588386
Would it be saying that if you had a marble on a scale, it would weigh X grams, but if you rolled the same marble on the scale so that the marble was moving, it would then show something like X + 0.000000000001 grams? For the sake of argument, let's imagine that the scale was able to show the mass with this absurd level of accuracy.

Anonymous at Mon, 17 Feb 2025 00:25:14 UTC No. 16588596

>>16568083
>>16569980
See:
>>16586976

Anonymous at Mon, 17 Feb 2025 00:28:45 UTC No. 16588599

>>16571905
If you aren't already aware, this is the source of your picture.
https://settheory.net/

Anonymous at Mon, 17 Feb 2025 02:55:56 UTC No. 16588686

>>16588444
Good question. The correct answer is complicated and depends on how you make the measurement. It also gets into the differences between special and general relativity. But essentially the mass is constant but more mass-energy means more curvature of space time which means more gravity produced.

Anonymous at Mon, 17 Feb 2025 07:30:28 UTC No. 16588903

is convergent evolution evidence that life finds a way to be alike

Anonymous at Mon, 17 Feb 2025 08:10:09 UTC No. 16588937

>>16588903
Not really. It can be explained by life just adapting to reproduce well in the circumstances. Filling enviromental niches and stuff.

Anonymous at Mon, 17 Feb 2025 08:13:43 UTC No. 16588942

>>16588903
Chess AI's that literally self-teach use openings that people have already discovered because it determined them to be good. If it works well for the situation, then it ain't gonna be the first and only time it's gonna occur

Anonymous at Mon, 17 Feb 2025 09:55:44 UTC No. 16589031

Wtf is going on here? I did the exact same thing but used the values given, what gives?

Anonymous at Mon, 17 Feb 2025 10:07:18 UTC No. 16589044

>>16588903
No, but because by the argument crabs are peak evolution.

Anonymous at Mon, 17 Feb 2025 10:30:15 UTC No. 16589064

>>16589031
It's not some 1-dimensional collision.

[eqn]400 \; \text{kg} \begin{pmatrix} 7 \; \text{km/s} \\ 0 \\ 0\end{pmatrix} + 1 \; \text{kg} \begin{pmatrix} \frac{-12}{\sqrt{2}} \; \text{km/s} \\ \frac{12}{\sqrt{2}} \; \text{km/s} \\ 0\end{pmatrix} = 401 \; \text{kg} \begin{pmatrix} v_1 \\ v_2 \\ v_3 \end{pmatrix} \\
v = \sqrt{v_1^2 + v_2^2 + v_3^2} \\
\beta = \arctan(v_2/v_1) [/eqn]

Anonymous at Mon, 17 Feb 2025 11:05:51 UTC No. 16589080

>>16589064
I can't get this to be correct even after turning the velocity into a vector quantity

Anonymous at Mon, 17 Feb 2025 12:52:53 UTC No. 16589201

>>16588686
But normally the implication of more mass is greater gravitational attraction. So if velocity increases mass then a moving object would be attracted to earth with a greater force right?

Or what if we imagine another example. Imagine you have the gyroscopic toy in picrelated. Normally it weights probably 200 grams. But now imagine you made it spinning with a gorillion rpm, so that the speed would increase the mass by ten fold and the mass became two kilograms due to special relativity (imagine it is made from a special material that can resist infinite forces so the toy is able to spin that fast without breaking apart). Then you put it on a scale, would the scale now show two kilograms instead of 200 grams?

Anonymous at Mon, 17 Feb 2025 13:39:53 UTC No. 16589229

>>16589201
Sure but ask yourself how do you 'weigh' something and what are you wanting to measure? Is it its mass or the gravity it generates?

Anonymous at Mon, 17 Feb 2025 16:20:19 UTC No. 16589313

I'm studying from Introduction to Electrodynamics by Griffiths, I don't get why he calculates the work using the force 3.12 but with opposite sign. If he is calculating the work to bring q in from infinity, and the force points exactly towards the origin (where we want to bring q in), shouldn't he calculate it using F without changing the sign?
Besides, I would expect the work to be positive, since negative work would mean that we are doing work in the opposite direction than the force, right? Where am I wrong?

Anonymous at Mon, 17 Feb 2025 16:40:44 UTC No. 16589331

>>16589313
There are a number of ways to look at it, but you could just call it convention.

Anonymous at Mon, 17 Feb 2025 17:26:07 UTC No. 16589356

>>16589201
Another weirdness is that presumably the density of the object also increases when it's moving faster? If mass is bigger but the volume stays the same, then an object also becomes denser the faster it is moving which is a weird thing to think about.

Anonymous at Mon, 17 Feb 2025 18:30:14 UTC No. 16589412

>>16589313
One charge is q, the other is -q, so -q^2

Anonymous at Mon, 17 Feb 2025 18:44:17 UTC No. 16589427

>>16589313
>>16589412
The two charges are attracted to each other. If anything, it should take Positive Work (say, +10 units) to pull them Away from each other. But the energy of a particle at infinite distance is conventionally set to be 0. This means that at the distance d or 2d (whichever you're focusing on), the energy should be negative (say, -10 units). So, -10 + 10 = 0 as expected.

The moon is captured into earths orbit, so for the same reasoning, the energy is negative so that at infinity it's at 0. An electron is captured by a proton, and so it's energy is -13.6 ev.

If you want to know the potential and kinetic energies, then you can use virial theorem - so 2T = -V - and T+V = E.

Anonymous at Mon, 17 Feb 2025 18:51:57 UTC No. 16589433

>>16589427
virial theorem is only for the moon and electron-proton hydrogen atom. For your griffith's problem, it's basically just V then. Maybe that was your confusion

Anonymous at Mon, 17 Feb 2025 18:53:01 UTC No. 16589434

How many distinct three dimensional tetris piece thingies is it possible to make with ten cubes?

Anonymous at Mon, 17 Feb 2025 18:58:01 UTC No. 16589436

>>16589434
346543 if you consider reflected versions to be different things
178083 if you consider them to be identical

Anonymous at Mon, 17 Feb 2025 23:25:10 UTC No. 16589682

What is the best or most efficient way to convert heat into electrical energy if the temperature of the heat is not high enough to run steam turbines?

Anonymous at Mon, 17 Feb 2025 23:53:15 UTC No. 16589698

>>16589682
The best contender for converting a low temp difference into work is probably a Stirling engine.

Anonymous at Mon, 17 Feb 2025 23:55:59 UTC No. 16589702

>>16589682
>>16589698
Followup, if it's a small amount of heat as well a Peltier device is much easier to use and it converts the heat directly to electricity.

Anonymous at Tue, 18 Feb 2025 01:56:27 UTC No. 16589765

>>16589682
The most efficient heat engine is the Carnot engine, so for your question, use a Carnot to perform work on a turbine, and this works for any nonzero temp difference. Issue with the carnot engine is that it moves extremely slowly. But the Carnot's max efficiency (which depends on the temp diff) is used to compare how efficient any other engine is to the optimal one.

Anonymous at Tue, 18 Feb 2025 02:40:34 UTC No. 16589809

Didn’t realize there was a dedicated general to this, so if someone could answer what I asked at >>16589497 I’d appreciate it.

Anonymous at Tue, 18 Feb 2025 02:42:48 UTC No. 16589811

>>16586928
I have a buddy in the UK who works on weather monitoring primarily in drones and balloons and does a lot of projects across the world (he’s in Kenya right now). He told me the NOAA shit has having a profound ripple effect on monitoring globally since stuff like the ARGO project is impacted. Makes my blood boil that such an objective public good for the whole world is getting gutted.

Anonymous at Tue, 18 Feb 2025 11:55:56 UTC No. 16590079

>>16589436
>346543
is prime

Anonymous at Tue, 18 Feb 2025 16:17:44 UTC No. 16590352

>>16589682
As the others have said, there are methods. What they haven't said is none of them are practical and / or generate only tiny amounts of electricity. You need a large temperature gradient to do anything useful.

Anonymous at Tue, 18 Feb 2025 16:17:45 UTC No. 16590353

Let [math]\mathcal{E}_{j}[/math] be generators of the [math]\sigma[/math] algebras [math]\mathcal{A}_{j}[/math] on the sets [math]X_{j}[/math]. Let [math](E_{j}^{k})_{k} \subseteq \mathcal{E}_{j}[/math] and [math]E_{j}^{k} \nearrow X_{j}[/math] as [math]k \to \infty[/math]. Then
[eqn]
A_{1} \otimes\, \dotsm\, \otimes A_{n} = \sigma\left(\{A_{1}\, \times\, \dotsm \times A_{n} : A_{j} \in \mathcal{E}_{j}\}\right)
[/eqn]
Why is the condition [math]E_{j}^{k} \nearrow X_{j}[/math] as [math]k \to \infty[/math] for a sequence [math](E_{k}^{j})_{k} \subseteq \mathcal{E}_{j}[/math] necessary? Can you give me a counter example?

Anonymous at Tue, 18 Feb 2025 23:08:01 UTC No. 16590841

Study and solve the system depending on the parameters [math]a[/math] and [math]b[/math].
[math]
\begin{cases}
x+y-z+t=1\\
ax+y+z+t=b\\
3x+2y+at=1+a
[/math]
I can get to [math]a=2[/math].
For [math]a=2[/math] [math]b[/math] can either be either 2 or not 2. If [math]b=2[/math], the system has infinitely many solutions with two free variables. If not, there are no solutions.
Otherwise if [math]a\neq 2[/math], [math]b\in \Bbb R[/math] and the system has infinitely many solutions with one free variable.
The thing is I also get [math]a=1-\dfrac{2z}{t}[/math] and [math]b=1+\dfrac{2z^2}{t^2}[/math].
Therefore I believe I have not arrived at a solution.
Can anyone help?

Anonymous at Tue, 18 Feb 2025 23:11:03 UTC No. 16590844

Study and solve the system depending on the parameters [math]a[/math] and [math]b[/math].
[math]
\begin{cases}
x+y-z+t=1\\
ax+y+z+t=b\\
3x+2y+at=1+a
\end{cases}
[/math]
I can get to [math]a=2[/math].
For [math]a=2[/math], [math]b[/math] can either be either 2 or not 2. If [math]b=2[/math], the system has infinitely many solutions with two free variables. If not, there are no solutions.
Otherwise if [math]a\neq 2[/math], [math]b\in \Bbb R[/math] and the system has infinitely many solutions with one free variable.
The thing is I also get [math]a=1-\dfrac{2z}{t}[/math] and [math]b=1+\dfrac{2z^2}{t^2}[/math].
Therefore I believe I have not arrived at a solution.
Can anyone help?

Anonymous at Wed, 19 Feb 2025 04:29:35 UTC No. 16591085

am I b&

Anonymous at Wed, 19 Feb 2025 06:44:46 UTC No. 16591143

>>16590844
3 equations can only solve 3 unknowns, so just choose x y and z to be your variables and a b and t to be you constant parameters. If you don't know how to do a basic linear 3 equation 3 unknown problem, look up a youtube video on it. It's simple to do, but too hard to describe without pictures to look at.

Anonymous at Wed, 19 Feb 2025 06:45:46 UTC No. 16591144

>>16590844
look up solving a system of equations, 3x3 matrix

Anonymous at Wed, 19 Feb 2025 10:48:17 UTC No. 16591291

>>16590844
I think you're supposed to solve for x,y,z,t not the other way round.

Anonymous at Wed, 19 Feb 2025 11:01:01 UTC No. 16591301

>>16590353
Because you need sets of the form X x A x X x X... in there. Take a set X and a subset A of X. Then the sigma algebra S=sigma({A}) is {0,A, A^c, X}. So for n=1 it's not necessary. If you also have a space Y and a subset B of Y with T=sigma({B}), then while they both individually generate S and T, { E x F : E in {A} and F in {B} } does not generate the product sigma algebra of S and T (because you only get {0, AxB, (AxB)^c, XxY }, while XxB should be in there as well, for example).

Anonymous at Wed, 19 Feb 2025 11:57:21 UTC No. 16591351

In quantum mechanics, if two observables don't commute that means they can't be measured at the same time. What does that mean?
Imagine we have two entangled particles and we measure in 1 the spin in the x-axis and in 2 the spin in the z-axis with a Stern Gerlach experiment. According to quantum mechanics, this is forbidden.
What happens then? Does the universe collapse? Do we get both up and down measurements at the same time?

Anonymous at Wed, 19 Feb 2025 12:14:02 UTC No. 16591361

>>16591351
>What does that mean?
It means that there are no experiments which can measure both those observables at the same time. This follows from the fact that any measurement is just an entanglement of the particle with a macroscopic observable.
>measure in 1 the spin in the x-axis and in 2 the spin in the z-axis
These are commuting observables.

Anonymous at Wed, 19 Feb 2025 14:43:25 UTC No. 16591448

1.If the galaxy expands faster than the speed of light, does that mean there is a boundary beyond which gravity cannot exercise any effect on us? I dont mean 10^-9999999999, but exactly 0 m/s^2?

2.Apparently the furthest galaxy that we can observe is 33.6 billion light years away (JADES-GS-z13-0). If we assume an empty space with two atoms hydrogen, separated by 33.6 billion years, will be drawn to each other by gravity? (after it reaches them, regardless how negligent it is?)

Anonymous at Wed, 19 Feb 2025 15:50:19 UTC No. 16591496

>>16591351
> According to quantum mechanics, this is forbidden.
It is not forbidden however the result is uncertain because fundamentally you can't measure two things at once. In the math of quantum mechanics this is expressed as acting with each operator in order, but for operators (observables) that don't commute the order matters: [math]\hat{S}_{x} \hat{S}_{z}|\psi\rangle \neq \hat{S}_{z} \hat{S}_{x}|\psi\rangle[/math]

So if you try and make this "dual measurement" there is an uncertainty in what answer you will get.

Anonymous at Wed, 19 Feb 2025 16:02:37 UTC No. 16591515

>>16591448
1. theoretically yes because gravitational waves also travel at the speed of light
2. see above

Anonymous at Wed, 19 Feb 2025 16:48:48 UTC No. 16591562

Even on this board I get censored lol.
https://warosu.org/sci/thread/16590818
Asking about statistical methodology was too much... deleted after 12 hours.

Anonymous at Wed, 19 Feb 2025 16:52:55 UTC No. 16591568

>>16591562
Btw, apparently the "trick" is called Everest regression:

>An Everest regression is what you get when you decide to control for an essential characteristic of the thing you’re interested in; ‘controlling for height, Mount Everest isn’t that cold’.

https://marginallyproductive.com/2020/06/14/the-everest-regression

But there is complete plausible deniability. There is nothing technically wrong. It is basically a means of obfuscation.

Anonymous at Wed, 19 Feb 2025 22:14:19 UTC No. 16591890

>>16591562
>>16591568
My german is poor, so I didn't read the paper, but from what I could gather from your posts: it's not quite the same thing, since the paper is trying to ascertain a causal relationship, while the everest example is just a poorly specified model.
If you're interested in whether *being a migrant at all* has an effect on one's propensity to crime, you want to control for any confounders, such as age.
(Maybe being young makes you more likely to be a migrant and more likely to commit a crime. Then simply regressing crime on `dummy_migrant` makes any causal interpretation basically impossible because you're unable to separate what `dummy_migrant` implies about the crime_rate, and what `dummy_migrant` tells you about age+what age tells you about the crime rate.)
In abstract terms, if you have a causal DAG with X (migrant) maybe influencing Y (crime rate), and variable(s) Z influencing both X and Y, you're only interested in the effect from X to Y directly (i.e. not its confounding effect through Z). Controlling on Z makes this possible.

In the everest example, this is different. If you're interested in whether mount everest is cold at its peak, there's no reason to control for height, because this has no causal link to *being mount everest* (in this case there's no reason to perform a regression at all, I would say, so the example is not perfect).
If you control for height anyways, you then could see that the coldness is fully explained by the height, but if you're not careful you might not look at the control variables' coefficients, and misinterpret "mount everest's peak is not cold" because the constant term or the coefficient of `dummy_everest` or whatever is approx. zero or the average temp on earth or ...

>I get censored
>But there is complete plausible deniability. There is nothing technically wrong. It is basically a means of obfuscation.
Schizobabble.

Anonymous at Thu, 20 Feb 2025 01:03:33 UTC No. 16592017

For the area enclosed by the curves y=0, y=8, and y=x^(3/2) we can find a solid of revolution using the shell method with the expected volume being equal to 192pi cubic units. When we integrate in terms of y with the integrand as 2pi y(y^(2/3)dy with upper limit y=8 and lower limit y=0 we find the correct volume. When we integrate with the integrand 2pi x(8-x^3/2)dx with upper limit x=4 and lower limit x=0 we find a value that is off from the correct volume by a multiplication exactly equal to (volume found)(7/2). What is a general method to arrive at the scaling factor for any solid of revolution problem so we may choose to integrate with respect to either variable and find the correct volume?

It may be helpful to notice that when only finding the area under the curve for the integral y=0 to y=8 (y^2/3)dy area found is equal to area found by the integral x=0 to x=4 (8-x^3/2).

Anonymous at Thu, 20 Feb 2025 01:36:07 UTC No. 16592043

>>16591890
While this seems plausible, the problem is the overall framing. Their conclusion generalizes that "there is no causal link between migration and higher crime rates." But if we view the demographic composition - being predominantly young males - as an inherent and inseparable feature of recent migration in Europe, then this framing is obfuscating. There is a semantic jump from *being a migrant at all* to *migration in general*.

Crémieux seems to agree with me, commenting on this study:

>{Controlling for the quality of ingredients, preparation, location, meals, staff, and atmosphere} McDonald's is indistinguishable from a five star restaurant.

https://x.com/cremieuxrecueil/status/1892279616171041182

Anonymous at Thu, 20 Feb 2025 02:20:28 UTC No. 16592069

You have a closed loop (like a rubber band) which is always one unit long. No matter which shape the loop is in, it can always fit inside the region A. What is the minimum area of region A?

Anonymous at Thu, 20 Feb 2025 02:55:59 UTC No. 16592099

>>16592069
A circle is the smallest A if I understand the question correctly, so pi times a quarter the unit quantity squared, or pi/16 units squared.

Anonymous at Thu, 20 Feb 2025 03:37:42 UTC No. 16592120

>>16592099
But how do you know it can't be smaller?

And to clarify. The loop can be rotated to make it fit. So the same shape rotated to different angles counts as the same loop.

Anonymous at Thu, 20 Feb 2025 07:04:11 UTC No. 16592238

>>16592069
You can't define any area because you have only defined the length of the band, it has zero width until you give us one.

Anonymous at Thu, 20 Feb 2025 07:48:36 UTC No. 16592268

>>16592069
https://en.wikipedia.org/wiki/Moser's_worm_problem

Anonymous at Thu, 20 Feb 2025 07:49:07 UTC No. 16592269

>>16592017
There's no scaling factor. If your factor isn't equal to 1, then you're doing two different problems (can you figure out which physical problem they correspond to?). If you want to do a variable change, then, just do a variable change as you normally would in calculus, so for you just dy = (dy/dx) dx, kek.

Anonymous at Thu, 20 Feb 2025 08:30:40 UTC No. 16592299

>>16592043
Well, sure. Unless I've misunderstood all this time, the argument of a migrant-skeptic isn't "we should be wary because they commit crimes at roughly the same rate as the native young male population" (probably because this isn't true), but it's what your semantic jump amounts to (assuming they only controlled for age and gender, again, I didn't read it).

Maybe this is clearer in your examples: say you read "controlling for height, mount everest isn't very cold" as a headline somewhere. You'd hope no one gets the idea that "mount everest's peak is not that cold", and, being somewhat statistically conscious, you decide to look at the study, and notice the significant coefficient in front of `height`.
What this tells you is that 1) the headline is shit, and 2) the coldness is very well explained by the height of the peak.
(There's a lot more you should still investigate before trying to draw any conclusion from the regression, but that's beside the point.)
Similarly, if you read "controlling for ingredients, preparation, location, meals, staff, and atmosphere, mcd's is a good restaurant", you should draw similar conclusions; the quality of the restaurant is probably thoroughly explained by "ingredients, preparation, location, meals, staff, and atmosphere".

>cremieux on twitter
Who? What?

Anonymous at Thu, 20 Feb 2025 09:26:29 UTC No. 16592349

>>16584917
how can i get a real STEM degree that I can put on my resume without amassing big debt?
i found OSSU open source CS cirriculum, but even if i do all of this, I wont get the fancy piece of paper.

Anonymous at Thu, 20 Feb 2025 10:18:59 UTC No. 16592430

How do I do well on my controls course? Its so fucking hard. I've spent more time on it than all other courses but it still looks like Greek to me. I'm not even a quarter of the way through the semester and I already know I'm failing.

🗑️ Anonymous at Thu, 20 Feb 2025 20:13:53 UTC No. 16593681

Why is it so counter-intuitive to think that A percent of B is always the same as B percent of A? Like imagine you're cooking or something and you take 17% from three 30 grams of salt. Then that would be the same as taking 30% of 17 grams of salt. Why can't I understand this?

And I know you can do algrebraic trickery like A% of B = (A/100)*B = (A*B)/100 = (B*A)/100 = (B/100)*A

How can you see this without math?

Anonymous at Thu, 20 Feb 2025 20:17:47 UTC No. 16593693

Why is it so counter-intuitive to think that A percent of B is always the same as B percent of A? Like imagine you take 17% from 30 liters of water. Then that would be the same as taking 30% of 17 liters of water. Why can't I understand this?

I know you can do algrebraic hocus pocus like A% of B = (A/100)*B = A*(1/100)*B = (B/100)*A

How can you understand this without algebra?

Anonymous at Thu, 20 Feb 2025 21:52:40 UTC No. 16593940

>>16593693
it's because the relationship is inverse. if A is 4/10 of B which is 40% then B is 10/4 of A which is 250%
different approach would be to think that A and B represent an amount (or mass or whatever) and 4 lots of B are equal to 10 lots of A therefore to make them equal you have to increase A by a factor of 10/4 (250% of it) or decrease B by 4/10 (40% of it)

Anonymous at Thu, 20 Feb 2025 23:05:19 UTC No. 16594060

>>16593693
>why is it counter-intuitive
Because the fact that multiplication and division numbers commute isn't perfectly intuitive. Take one square block, double it, then cut that rectangle in half, and you end up with the same block. Take the original square block, cut it in half, then double that half block, and you end up with the same block. Is it the same if you do it with 3 instead of 2? Is it the same if you do it with pi instead of 2? On the other hand, multiplying two numbers commutes is very easy to understand since a 2x3 rectangle has the same area as a 3x2 rectangle, or any other positive numbers. Is multiplying 3 numbers intuitive? Sure, just go to 3D. Is it intuitive that this works multiplying 4 numbers? You can't see 4D, so no, but you trust the simple cases.

For intuition, you basically accept the proof the division and multiplication don't care about order and move on. You focus on the simple cases, and trust them to extend the rule to less intuitive objects.

Anonymous at Thu, 20 Feb 2025 23:06:25 UTC No. 16594062

>>16594060
>2x3 rectangle has the same area as a 3x2 rectangle...
(why? Just rotate your head)

Anonymous at Thu, 20 Feb 2025 23:51:39 UTC No. 16594139

>>16593693
just ignore the percent.
giving 17 people 30 liters of water each is clearly the same as giving 30 people 17 liters of water each. lets say you took that water from a tank that holds 1000 liters. what proportion of the water did you use?
in the first case:
[math] \displaystyle
\frac{17 \times 30}{1000}
[/math]
in the second case
[math] \displaystyle
\frac{30 \times 17}{1000}
[/math]
you used the same *amount* of water in both cases, so you clearly used the same *proportion* of water in both cases.

Anonymous at Fri, 21 Feb 2025 00:11:30 UTC No. 16594174

>>16592349
spend a year lifting boxes in upstate NY, apply for residency, then apply to SUNY/CUNY. alternatively, CA WA or TX state schools.
then scholarshipmaxx and get a part time gig weekends

Anonymous at Fri, 21 Feb 2025 01:49:11 UTC No. 16594288

>>16594139
Do it without numbers and symbols

Anonymous at Fri, 21 Feb 2025 01:59:30 UTC No. 16594299

>>16594288
if half of all people in a room have a cookie, thats the same amount of cookie as if all people in a room have half a cookie.

Anonymous at Fri, 21 Feb 2025 04:49:11 UTC No. 16594435

>>16594299
Like this silly

Anonymous at Fri, 21 Feb 2025 06:53:48 UTC No. 16594496

What's your best anti-aging book?

Anonymous at Fri, 21 Feb 2025 09:38:39 UTC No. 16594595

>>16593693
>How can you understand this without algebra?
>17% from 30
This is the amount you want.
>30% from 30
You now have 30/17 times too much water, so you must decrease total amount by 17/30.
>30% from 30 * (17/30)
How convenient. That's just 17.
>30% from 17.
Done.

Anonymous at Fri, 21 Feb 2025 10:05:49 UTC No. 16594616

>>16593693
1. The proportion between two numbers is the factor by which you need to multiply the second number to get the first
2. The inverse proportion is the factor by which you need to multiply the first number to get the second
3. If you multiply the first number by the inverse proportion, and the second number by the proportion, they swap places
4. To maintain the same relative amount, when you scale the percentage by a factor, you have to scale the total amount by the inverse factor
5. Consider the proportion of the percentage to the total amount
6. You scale the percentage by this proportion
7. You scale the amount by the inverse proportion
8. The number swap places
9. The relative amount remains the same

Anonymous at Fri, 21 Feb 2025 14:12:10 UTC No. 16594812

>>16585855
Ok, so to show that [math]\cup_\alpha f(A_\alpha) \subseteq f(\cup_\alpha A_\alpha)[/math] then I need to show that [math]y \in \cup_\alpha f(A_\alpha)[/math] is also in [math]f(\cup_\alpha A_\alpha)[/math]. So if [math]y \in \cup_\alpha f(A_\alpha)[/math] then there is an [math]x \in A_\alpha[/math] such that [math]y=f(x)[/math]. It follows that [math]y \in f(\cup_\alpha A_\alpha)[/math] because [math]x \in A_\alpha[/math] is also in [math]\cup_\alpha A_\alpha[/math].

[eqn]\text{Using } f(x) = x^2 \text{ to show that } \cap_\alpha f(A_\alpha) \nsubseteq f(\cap_\alpha A_\alpha).
\\
\textbf{A} = \left\{ p,q,r \right\}
\\
A_p = \left\{ -3,-2,-1,0,1,2,3 \right\}
\\
A_q = \left\{ 0,1,2,3 \right\}
\\
A_r = \left\{ -3,-2,-1 \right\}
\\
f(A_p) = \left\{ 0,1,4,9 \right\}
\\
f(A_q) = \left\{ 0,1,4,9 \right\}
\\
f(A_r) = \left\{1,4,9 \right\}
\\
\cap_\alpha f(A_\alpha) = \left\{ 1,4,9 \right\}
\\
f(\cap_\alpha A_\alpha) = \emptyset
\\
\therefore \text{ } \cap_\alpha f(A_\alpha) \nsubseteq f(\cap_\alpha A_\alpha).[/eqn]

I can probably show that for arbitrary indexed family of sets with disjoint subsets that have intersecting image sets but maybe when I get bored sometime.

Anonymous at Fri, 21 Feb 2025 16:45:00 UTC No. 16595040

>>16594435
Eudoxus

Anonymous at Fri, 21 Feb 2025 21:00:08 UTC No. 16595436

>>16584917
>stupid
Do astronomers still use a Julian calendar?

Anonymous at Fri, 21 Feb 2025 21:48:35 UTC No. 16595496

>>16595436
No.

Also it's stupid as in simple, not stupid as in retarded.

Anonymous at Fri, 21 Feb 2025 22:00:54 UTC No. 16595512

>>16595496
What is Julian epoch J2000.0, then?

Anonymous at Fri, 21 Feb 2025 22:22:51 UTC No. 16595549

>>16595512
Despite the name that has nothing to do with the Julian calendar. A Julian year is just a definition of time.

Anonymous at Sat, 22 Feb 2025 03:15:35 UTC No. 16595885

So how many is it?

Anonymous at Sat, 22 Feb 2025 04:29:02 UTC No. 16595925

>>16595885
it can't be that hard to calculate, right? it's related to the birthday paradox

Anonymous at Sat, 22 Feb 2025 04:36:46 UTC No. 16595928

>>16586810
the blossom samurai

Anonymous at Sat, 22 Feb 2025 04:39:41 UTC No. 16595930

>>16586810
sweet home Alabama

Anonymous at Sun, 23 Feb 2025 17:06:38 UTC No. 16597423

I was told that the most important theorem in physics was discovered by a woman. Is that true?

Anonymous at Sun, 23 Feb 2025 19:35:09 UTC No. 16597547

>>16597423
i believe this is what you've been told about
https://en.wikipedia.org/wiki/Wu_experiment

Anonymous at Sun, 23 Feb 2025 19:36:29 UTC No. 16597549

>>16597423
> the most important theorem in physics
That's subjective. How is that judged? Anyway, assuming they were talking about Noether's theorem, then it is certainly in contention. It's a key component of the Standard Model and tells us how fundamental conservation laws and fundamental properties like energy and momentum exist.

Anonymous at Sun, 23 Feb 2025 21:20:23 UTC No. 16597629

I have three travel blankets I purchased at a trucker gas station, they're great but made of some kind of plastic fiber. I've noticed the fibers shed and I'm pretty sure they're getting into my eyes and lungs, they're certainly in my hair and all over surfaces. I know the lungs are not very good at clearing things like that out, so what's an effective method to de-plastic my body? One thought was inhaling steam to attempt to trap and cough it up.

Anonymous at Sun, 23 Feb 2025 21:23:02 UTC No. 16597634

>>16597629
Here's a pic of one said fiber, it's about average length from my observations. I found this one stuck to my skin.

Anonymous at Mon, 24 Feb 2025 01:12:34 UTC No. 16597848

Watching a youtube video made me think of an interesting physics problem. You have a bugatti which weighs 1995 kilos and it goes 1/4 miles in the time of 9.6 seconds. Then I wondered what is the minimum number of horsepowers by which this could be achieved assuming there was no energy loss?

I figured that the power would have to be constant the the whole time (in which case acceleration would not be constant). So just assuming constant acceleration and finding the horsepowers that way is not going to give the right answer (in fact I already did it in this way and got 978.5 hp).