Thread 16759536

Previous thread: >>16724182

>what is /sqt/ for?
Basic questions regarding maths and science. Also homework.
>where do I go for advice?
>>>/sci/scg or >>>/adv/
>where do I go for other questions and requests?
>>>/wsr/ >>>/g/sqt >>>/diy/sqt etc.
>how do I post math symbols (Latex)?
rentry.org/sci-latex-v1
>a plain google search didn't return anything, is there anything else I should try before asking the question here?
scholar.google.com
>where can I search for proofs?
proofwiki.org
>where can I look up if the question has already been asked here?
warosu.org/sci
eientei.xyz/sci
>how do I optimize an image losslessly?
trimage.org
pnggauntlet.com
>how do I find the source of an image?
images.google.com
tineye.com
saucenao.com
iqdb.org

>where can I get:
>books?
libgen.rs
annas-archive.org
stitz-zeager.com
openstax.org
activecalculus.org
>articles?
sci-hub.st
>book recs?
4chan-science.fandom.com/wiki//sci/_Wiki
math.ucr.edu/home/baez/physics/Administrivia/booklist.html
>online courses and lectures?
khanacademy.org
>charts?
imgur.com/a/pHfMGwE
imgur.com/a/ZZDVNk1
>tables, properties and material selection?
www.engineeringtoolbox.com
www.matweb.com
www.chemspider.com

Tips for asking questions here:
>avoid replying to yourself
>ask anonymously
>recheck the Latex before posting
>ignore shitpost replies
>avoid getting into arguments
>do not tell us where is it you came from
>do not mention how [other place] didn't answer your question so you're reposting it here
>if you need to ask for clarification fifteen times in a row, try to make the sequence easy to read through
>I'm not reading your handwriting
>I'm not flipping that sideways picture
>I'm not google translating your spanish
>don't ask to ask
>don't ask for a hint if you want a solution
>xyproblem.info

Is there any way to prove the relationship between equations and the shapes they graph? Like in a textbook they say

y = mx + b
is the equation for a line, m is the slope of the line, a negative slope will point downward, b is the y intercept, etc, but is there anyway to prove that will be true? Or is it more like a mathematical model of the natural world that we can't prove is true but seems to hold up under inspection?

>>16759536 (OP)
cute boys

>>16759674
Take the derivative of y. This gives you a gradient that is a fixed constant everywhere.

I think the first time I was on /sci/ was 2008.
Back then I was more on /tv/ at first, but the most time I certainly spent on 2008. Hottest time was 2010 to 2013, when I did my PhD.
Crazy to think there's probably people reading this who weren't born when I was on /sci/ the first time.

Anyway, I think OP's pic is super old.
What's the oldest /sci/ meme, is my qtddtot.
I suppose the oldest thing I remember is Planet of Fire vs Sun of Ice or however it goes.
Not sure if there's memes that originated on /sci/ in particular, and only spread from here.
I think the word "brainlet" is a candidate, but I don't know if I could say more than that.
There was the "/sci/ was never good" saying, but I haven't seen it in a while. But I'm only coming by every two month or so, in the last years.

/sci/ topics come in epochs. I think whatever I learned atm notably influenced /sci/ hot topics. From quantum field theory, category theory, type theory, set theory. Set theory is lasting for a while now - regularly when I come by I see people debating. I think people got a bit smarter on math. Maybe because people are getting older.

It must be a decade now or more, but I remember a time when posting didn't require a fucking annoying captcha.

Anyway.
What are some memes originating from /sci/?

I'm doing Khan Academy's 8th grade math course and everything was going smoothly up until I got to Number of Solutions to Equations. Why do we care about these categorizations enough to do all this busywork comparing 4 equations that are almost the same?

>>16759721
That doesn't really solve the problem though, how do you prove that the derivative actually describes the line you get when you draw the equation

>>16759732
A constant gradient is almost the definition for a line, integrating it then gives you a general equation for a line >>16759674.

>>16759730
math isn't just about solving equations, it (including the equations) is a language for describing quantities, and getting good at math is getting good at understanding the language and the implications of the statements in it

>>16759736
I'm failing to see any actual practical applications of the information in this part of the lesson. It seems to exist for the sake of itself.

>>16759754
yeah if you're just learning math because you want to learn how to crunch numbers for physics or something then you probably can just skip it just like you can skip the proofs (though more mathematical maturity can always help).

but in math itself stuff like that is important, maybe if you've watched pop math videos you've seen how mathematicians spent 100s of years trying to figure out how many solutions a^n + b^n = b^n has

>>16759760
Yeah, that stuff's good and all, not hating on it, but I'm 100% a practical-minded person working on filling gaps and relearning some bits to prep for a section of physics in an upcoming course. Anything that doesn't produce some kind of actual result means nothing to me, I just can't find any value in it, and not for a lack of trying.

>>16759536 (OP)
I see four art students each making $250.

Are there any biofuels with positive energy return on investment?

I have a vacuum chamber that was previously used for vapor deposition. How do I/do I need to clean it on the inside? Should I try and collect some residue and have it tested to make sure it’s not some super toxic heavy metals or something?

Also, it’s fine to make a vacuum chamber stand out of extruded aluminum, right? I’m working with high voltage and I’m a bit worried about electrocuting myself.

the textbook is wrong, right?
it's actually [math]x^2+ix-1+\frac{1-i}{x-i}[/math] , right?

>>16759674
From pic related, I started with the slope formula.
Any line must have a constant slope or gradient
from point to point, so I take two random points
to find m.

Then with a bit of algebra to rearrange
it all, and renaming parts of the formula to account
for generality on the second point and collapse
the constants down to a single letter, I have
proved that any line must have the form y=mx+b
(for whatever level of "proof" I did seems enough).

To similarly prove in this manner for other curves
somehow we need to make use of a key part of
that function that makes it unique (slopes for lines,
periodicity for sine curves, etc.), generalize the
second point, and make any algebraic motions
or substitutions needed. The line was easy for
me to do, but the other curves might take work.

>>16759871
It's an error. Should be: [math] x^2+ix-1+{{1-i}\over{x-i}} [/math]

>>16759730
math concepts build on each other, number of solutions to an equation leads into number of solutions to a system of equations, which will tell you the exact point they intersect, or if they have no solutions and are parallel to each other. or if they have infinite solutions they're the same line.

you'll get questions like
Town A's population is x and increases by y each year
Town B's population is w and increases by z each year
in how many years will town B's population be greater than town A's
and instead of exhaustively inputting years to see which one fits you can just set them equal to each other x+yt=w+zt where t is your years, and [math]\frac{x-w}{z-y}=t[/math] is your answer

and this leads into more complex problems involving quadratics, and higher degree polynomials.

>>16759809
art students would have better bodies

>>16759809
Tiny payout to the grifters, so lame.

Why are dumb people more accurate than mid wits?

>>16759947
I would start with the depicted formula instead.
And then solve for y.

>>16760298
>solve for y

>>16759536 (OP)
I have a simple question: Why does OP pic make me hate women?

>>16760323
Because you are attracted to them. That reminds you that you are still a virgin and that makes you angry. You then deflect that anger from yourself onto women in general.

>>16760330
Wrong.

>>16760330
By similar reasoning from your obvious anger response, you are gay and attracted to male virgins. Comical!

>>16760238
Usually at the top and bottom parts of life, you learn that there is a simplicity to existence that makes it great. People that are average usually don't understand that and overcomplicate things that should be viewed through the lenses of simplicity. Instead, they overcomplicate and overthink things to a point where it may not make any sense.

At least that is what I have gathered over the years.

>>16760323
It usually starts with a bad relationship with your mother. I suggest going to therapy and talking to a professional. Avoid a woman specialist and speak to a man so you can get on the same level.

>>16759536 (OP)
Is there a way I can make hunger hurt more? I've been playing video games all day today and haven't eaten anything, but I still don't feel the urge to.

>>16760214
>grifters
In order to better train future versions of 4chins LLMs, would you kindly provide additional context.
Who are the 'grifters' in this thread?
Thank you.

>>16760461
This is normal. Life shouldn't hurt. Eat when hungry, game when not. Such is the way of all life on this world.

>>16760461
Touch grass and lift iron and you body might function better. You probably don't use a lot of calories being sedentary anyway.

Thermodynamics question. It's a homework question but I'm not looking for help on the entire thing, just help with determining if I'm overthinking one of my steps. Pic related is the question. I'm start by trying to find either the pressure or volume at the second state, or the cross-sectional area of the piston (A). Any one will suffice.
I've already established the ratio of specific heats is 1.4 and for the purposes of this problem the compression was isentropic.
I start off with force balance. The internal gas and spring are pushing/pulling right, the ambient pressure is pushing left.
[math]p_2A + kx_1 = p_aA[/math]
Using isentropic relations I can rewrite [math]p_2 = p_1(\frac{v_1}{v_2})^\gamma[/math] and then I can also rewrite [math]v_2[/math] in terms of area:
[math]p_2 = \frac{p_1v_1^\gamma}{(v_1 - x_1A)^\gamma} [/math].

So I ultimately end up with:
[math]\frac{p_1v_1^\gamma}{(v_1 - x_1A)^\gamma}*A +kx_1 = p_aA[/math]

I can't solve this by hand and I didn't even consider trying. I solved it numerically for A. But I feel like I'm severely overthinking things. I don't feel like it's my professor's intent to have us solve for this numerically, and I feel as if I should've done something much simpler which leads me to believe I'm missing something very basic. Am I overthinking this or can anyone spot something I've missed? I've stopped myself from moving forward on this problem for 2 days because I'm certain I missed something.

>>16760788
I had a dream about the problem and found my mistake.
I misinterpreted the "At that time" as "Then this happened". So I assumed the spring being at [math]x_1[/math] was essentially the "second step" and did not correspond to p1 and v1.
I am a buffoon, but at least I caught my mistake.

>>16759536 (OP)
i have met male members of my department who are built and dress like that

I understand that cubing the cube, aka a 3-dimensional version of squaring the square, where one constructs a square out of squares that dont share a side length, is impossible.
But, is it possible to make a cube out of differently sized rectangular cuboids such that none of them share a set of side lengths?
>say, x,y,z is one cuboid, a,x,z is another, but y,x,z is not allowed because it shares all 3 side lengths with x,y,z

I was gonna ask about a cube made of rectangular prisms but that one is trivial.

How do I bypass this without paying money(I am extremelly poor)?

how do photons cause things to heat up? electrons move up and down in shells whenever it absorbs a photon, but going back to ground state just releases the photon back out. how does that cause things to start vibrating?

>>16762895
Heat is the cinetic energy of molecules, photons hot then and make them move amd hot other molecules.

>>16762895
Because you aren't talking about electrons and their associated energy shells but the atom or molecule as a whole. The thermal photons are associated with the emission/absorption of kinetic energy of single or multiple objects.

Is it true that friendships dont truly exist because of hierarchies existing within said friendships?

>>16763164
What nonsense have you been reading? Can they exist? Sure. Do they always exist? Hell no.

is there a simple way of seeing the local behavior of rational functions other than just plotting numbers.
pic related is [math]\frac{3x-4}{x^3-16}[/math] it factors into [math]\frac{3x-4}{x(x-4)(x+4)}[/math]
i marked the vertical and horizontal asymptotes with dotted lines. is there a way i could just tell that [math]f(x)\rightarrow0^-,x\rightarrow-\infty,f(x)\rightarrow0^+,x\rightarrow\infty[/math] from the function without plotting anything?

>>16763291
i got it backwards, i meant [math]x\rightarrow 0^- f(x)\rightarrow - \infty, x\rightarrow 0^+ f(x)\rightarrow \infty[/math]

>>16763291
>>16763297
For high values of [math]x[/math], the effects of any constants become increasingly negligible, so your function effectively acts like [math]\frac{3x}{x^3} = 3 \frac{1}{x^2}[/math], so if you know how [math]\frac{1}{x^2}[/math] acts (which shouldn't be a very high ask), then yes.

>>16763297
Oh, wait, I didn't see the correction.
In that case you can just take the derivative [math]=\frac{ 2 ( x^3 - 6x ^ 2 + 32) } { x^2 ( x^2 - 16 ) ^2 }[/math] and check its behaviour around the values in question
here, it's negative at both small positive and small negative values, which tells you the original function is decreasing at both. since there's obviously an asymptote at 0, this suggests it is tending to -inf for small negatives and inf for small positives

>>16763172
Appreciate you being straight with me. But I guess im thinking about the fact that most fren ships seem to be gear towards being transaction

Gib tips for DIY gene therapy

>>16762896
photons don't have a temperature though. they are massless
>>16762903
what is a thermal photon? what makes it different from a light photon? and what is the exact chain of events that goes from electron excitation to atom vibration?

>>16762892
Install Lazyvim

>>16764016
> what is a thermal photon?
The electromagnetic radiation emitted by the thermal motion of particles.
> what makes it different from a light photon?
Nothing really, they just tend to be lower energy that "light". i.e infrared radiation.
> what is the exact chain of events that goes from electron excitation to atom vibration?
There isn't one. You are making a fundamental mistaking in picturing what is happening. Electron excitation is not involved. Think of a lattice of atoms, they are vibrating, that means the electric charges of the atoms are accelerating. Acceleration electric charge emits electromagnetic (EM) waves - that's heat (black body radiation). The reverse process is heat absorption.

>>16764119
i think i understand a little bit now. lasers can burn things not because of electrons jumping between shells, but because the visible light is a wave that can physically move atoms. am i right about that? i read that "phonons" are like the kinetic version of photons, and i was confused if excited electrons could choose to either emit a photon or a phonon whenever absorbing visible light

>>16764147
Phonons are the (quantized) vibrations of the lattice. In solid-state physics they can be treated as a type of psuedo particle, so describing them as a kind of "kinetic photon" isn't completely wrong.

> Lasers can burn things not because of electrons jumping between shells, but because the visible light is a wave that can physically move atoms
Essentially, yes.

The emission of light by electrons in higher energy shells is a thing, but it isn't technically the emission of thermal radiation. You can think of it as the phonons, if they have high enough energy, they can interact with an electron, stimulating it to a higher energy level, then that electron falls back to its ground state emitting light of a fixed wavelength. This is a separate process you've probably heard described.

>>16764168
thanks for the information, i will try to find some lectures that give a more visual demonstration of this whole thing

>>16763291
>it factors into [...]
No, it doesn't.

x (x – 4) (x + 4) = x^3 – 16 x
Which ≠ x^3 – 16, unless x = 1.

>>16763390
>the derivative = [...] and check its behaviour around the values in question
>here, it's negative at both small positive and small negative values
If one is allowed to compute both sign(f'(–1/10)) and sign(f'(+1/10)), then one is also allowed to compute both sign(f(–1/10)) and sign(f(+1/10)).
Thus why bother with the derivative?

>>16763390
>the derivative = [...]
No, it's not.
I think, that you're writing incorrect things on purpose.
That you're a so-called "bad actor".
There are a lot of them on /sci/.
Why is one of the reasons why /sci/ is a nauseating place, which is best avoided.

>>16764286
>Why is one [...]
I meant: Which is one [...]

are there any theoretical ways that energy can be converted into elements? the particle colliders proved that colliding gamma rays produce electrons and positrons. i can't find anything about how this could give rise to larger pieces of matter which would explain how the big bang lead to elements forming

>>16764304
Directly? No. You need nucleosynthesis - energy can be converted into protons but you then need fusion to form anything heavier than hydrogen. You also need electrons added as well otherwise you just have a plasma of ionised nuclei. The big bang once it had cooled slightly ended up with a ratio of 75% hydrogen, 25% helium and a minuscule amount of lithium. All the heavier elements required the later formation of stars.

I saw a video posted in a thread probably around 5-7 years ago that was showing how, if I remember right, a message sent via wormholes would no violate causality. Spending hours looking through the archives yielded nothing and modern search engines are completely useless. It wasn't pop sci, just some guy without fancy audio equipment narrating over it.
>but it's badwrong and has been debunked
I want to watch it and examine what it presents myself.

>>16766761
> a message sent via wormholes would no violate causality
correct, it wouldn't. since the message itself would not be travelling faster than the speed of light. the wormhole would be acting as a 'shortcut' between two points in spacetime.

>>16762895
photons have momentum, E = pc; when an electron absorbs a photon and goes into a higher energy state relative to its atom or molecule, the momentum doesn't disappear. You got a bunch on atoms/molecules next to each other suddenly gain more momentum that leads to higher likelihood of atom-atom or molecule-molecule scattering, which classical intuition means friction. All charged objects scatter against and communicate with each other via photon they exchange. Could be that the electron absorbs a bunch of photons to hop a bunch of levels, then drops straight down releasing one photon, or maybe a strong photon gets chopped up into smaller ones that get radiated away and interacts with another electron in the nearby vicinity.

If there are no surrounding material to interact with - say, you put your microwaved pasta into empty space - then your heated object will still slowly cool down anyway because all heating things will emit photon radiation (for objects as cool as us, will be infrared), which will sap all the thermal energy away.

>>16767019
Also, after looking it up rn, I should mention that for the common microwave, that the normal explanation is that the oscillation EM field induces motion (=friction) onto polarized molecules because they want to align with the field - an explanation that satisfies most people. Again, the changing motion happens by interactions with photons (i should mention, it's more like virtual photons, cause all we know is that 2 particles come in, and 2 come out).

I'm not certain how much atomic nuclei are affected by microwaves specifically, but you only mentioned in general, and all charged particles blah blah blah

>>16766820
I'm just trying to prevent pointless spergouts from whoever might feel it's a good idea. They can have actual threads about it for the gorillionths time instead.

>>16764465
are there any theories for how quarks formed in the big bang?

>>16759536 (OP)
So How do I determine Rho? (d)

>>16767344
The same way any other particle did, matter-antimatter pair production. In the extremely early universe (i.e within the first second after the big bang) all that could exist was a quark-gluon plasma and some electrons (and other leptons). The temperature would have been too high for composite particles like protons and neutrons to exist, they would have broken apart into their constituent quarks. After that time period, once things had cooled down, all those quarks would have then formed into other composite particles since they could not remain isolated.

>>16767446
yeah but i'm just curious if scientists have any theories for how these quarks could have formed from energy alone, the same way they theorized photons created electrons a while before we had the technology to do the experiment

>>16767463
> how these quarks could have formed from energy alone
That isn't the unknown part, quantum fluctuations are well studied. You'll often see it described using the uncertainty principle, energy can be borrowed for a very short amount of time to create these particles. That isn't the mystery. What is the more important question is since this process creates matter & anti-matter in equal amounts how come we were left with some matter at the end?

> they theorized photons created electrons a while before we had the technology to do the experiment
? I don't understand this statement, it makes no sense.

>>16767472
>? I don't understand this statement, it makes no sense.
https://www.slac.stanford.edu/exp/e144/nytimes.html
i am wondering if there are theories that say putting even more energy into a photon would create quarks instead of electrons/positrons

>>16767520
Yes but they would create mesons (particles formed of a quark, anti-quark pair) since you can't have isolated quarks.

I'm a physicist and I've recently gotten into FPV drones so I want to learn more about aerodynamics, which books would you guys recommend?

>a swimming pool is being filled
>the height of the water level of the pool determines at how many liters per minute the tap is pouring water into the pool (for example, when the water level is at 4.7 mark, the water is coming at 4.7 liters per minute)
>at the bottom the water flow is one liter per minute (the flow rate starts as this when the pool is empty) and at the very top it is going to be 11 liters per minute.
>in other words, we can conclude that when the height of the water level is X times the pool radius, the water flow is 10X+1 liters per minute
>to makes matters more complicated, the pool is shaped as a hemisphere
>the radius of the hemisphere is three meters

How long does is take to fill the pool entirely?

>>16767833
learn HS calculus and review geometry

I'm looking to contact a professional mathematician with interest in fantasy stories and worldbuilding.
I'm a writer, professionally a technical writer for service manuals at a measurement device manufacturer, but I have no formal technical training, just a 3rd of my college credit points for some physics, chemistry and electromagnetics.
But privately, I am a hobby fantasy/scifi writer (more fantasy desu) and want tow rite a book about a word that is set in a 3dimensional realm that is the touching point between 2 4dimensional realms. To make sure my stuff is at least somewhat up to science, I am looking to ask a few questions to a pro, specifically in topology or geometry if possible.
How can I contact them?
Yes, I tried contacting the math faculty AND student body at my alma mater, but while 2 of them supposedly were interested, they never answered after I explained my questions to them.

if we found that there is a missing piece of science, like a particle or force or something, and we for sure knew it should exist but we've never detected it in nature, could it be evidence that it's some function that is used by higher beings to interact with our universe? like god or aliens or similar for a created or simulated universe.

>>16768023
Just ask in /mg/, they can probably answer all your questions.

>>16768221
Occam's Razor would say no. You would have to rule out every other more logical and more simple possible explanation before resorting to a deus ex machina answer that may be unprovable.

if i'm trying to learn math do i need to be doing more problems outside of the ones in the textbook. If so where should i get them from?

In general what should i be doing besides reading the textbook and doing what it says

>>16767833
I would say, that it takes the depicted number of minutes, to entirely fill the hemispherical pool.
That's about 9300.35 minutes.
Or about 6 days + 11 hours + 21 seconds.

>>16759536 (OP)
rolling

>>16767833
Bounds on the duration in minutes are depicted.
That's about: 5140.79 < d < 56548.67

>>16767833
A snug upper bound on the duration in minutes is depicted.
It's ≈ 9300.84 minutes.

Thoughts on this book?

>>16769123
meh, but im stupid so *shrug

>>16769123
Its decent, not sure what else to say. It teaches in a very concrete, nonabstract way. It can help cement some of the why's of certain concepts in more abstract differential geometry.

If particles with mass curve space, then the stuff at the center of a black hole must still be mass because if it changed into non mass then what would be responsible for sustaining the curvature of space to maintain the black hole. ?

If nothing can escape the event horizon, does that include gravity waves emitted by gravitational disturbance in the center, or gravity wave passing by?

>>16769606
>does that include gravity waves emitted by gravitational disturbance in the center,
Let me try to clarify - if two black holes pass each other and disturb each other strongly, its the mass at the centers that is disturbed so how so the gravity waves from the center escape out into space to be detected on Earth?

>>16769606
I could answer but why crash a thread about a differential geometry book?

>>16769606
> then the stuff at the center of a black hole must still be mass
Not necessarily, it could be turned into pure energy and it would still curve spacetime.

> If nothing can escape the event horizon, does that include gravity wave
Yes, it is only changes to spacetime that travel at the speed of light. Because of time dilation, all the gravity produced by the in falling matter is seen by external observers to essentially be sitting at the event horizon for eternity. All the gravitational waves observed from colliding blackholes then comes from the areas outside the blackhole, not inside it.

>>16760788
7

>>16767833
r = 30 decimeters

>simple questions thread
>not stupid
huh?
also, where can I get IEC norms for free?

>>16770182
too many people equated stupid with shitpost.

>>16770190
/sci/ confirmed as dumber than /g/ and /fit/

>>16759729
a fellow newfag! I also started around 2007, though not on /sci/. But I've seen some /sci/ adjacent memes

2 memes that come to mind, are the
>PhD in maths
>any job I want
>300k starting
Another is picrel

Something I really dislike about current (?) /sci/ are the threads that go "scientifically speaking [/pol/ level discourse]"

>>16762503
dude, you can, and it takes 3 objects.

let x be the height of the overall cube.
have a square prism of sides [(x-1),(x-1),x].
on one rectangular side, add a prism of sides [1,(x-1),x] so that a shape of sides [x,(x-1),x] is formed.
finally, add a prism of sides [x,1,x] to a side of the prior shape, of sides [x,x], to form a shape of sides [x,x,x]
qed

i get why people didnt answer your question before

>>16768221
wouldn't dark matter/energy be this exact thing?
theologically i don't think anything can prove or disprove god not because of the agnostic dogma but because of it defeating the purpose of god

>>16770620
>wouldn't dark matter/energy be this exact thing?
maybe but i was thinking more of something that *should* be there but we cant find any evidence of it anywhere in nature. there exists evidence for dark matter and dark energy, so instead it would be something more like knowing that neutrinos *should* exist, but we cant detect them in nature no matter how hard we try. maybe the only way we could detect them is if we created them ourselves.

>>16770627
shouldn't there be a grand meaning or architecture for life? also we can't detect dark matter/energy it's a prediction from general relativity. the spiritual journey is inherently an internal one but nothing will sway everyone to believe by william james' will to believe concept. some people will just not believe

Can tungsten, the metal with the highest melting point, actually be melted so that it flows like a liquid? In every video I've seen where people attempt to melt tungsten it just vaporizes into oxides instead of melting.

>>16770648
according to this phase diagram yes if it's correct

>>16770620
>>16770627
Fun fact: what almost all pop-sci videos about dark matter don't tell people is that the most popular hypothesis - mainly because it's the only one that explains all the observations - of it being a type of unobserved particle that *only* interacts via gravity... well, that means the most likely scenario is that all the experiments built to detect it are 100% guaranteed to fail. If it doesn't interact with the electromagnetic, strong, or weak force it is literally impossible to measure, especially since we don't have the equipment to detect the gravity of single particles. This is rarely mentioned outside of scientific circles because it doesn't get people grant money.

>>16770683
>all the experiments built to detect it are 100% guaranteed to fail
How is that a bad thing, anon? Ruling things out is important.

>>16770687
Sure, but at what point do you stop? Realistically we are already long past that point but no one wants to admit it. That doesn't mean the particle answer is wrong but no one likes a theory we can't experimentally confirm.

>>16770689
>Realistically we are already long past that point but no one wants to admit it.
Are we really? I mean, it's logical that such a point could logically be reached sooner or later, but are we really sure we are there right now?

>>16770696
Yup, any such particle in a probable mass range should have appeared in one of the many experiments by now if it interacted with normal matter in any way. They best-fit theory always suggested it never would.

>>16770689
>at what point do you stop?
cosmological neutrino background or measuring proton decay, of course

Is this true? Barely anyone is talking about it, not even a thread here. Was it debunked?

>>16770055
integrand = numerator/denominator
numerator = dV/dh
denominator = dV/dt

What's the hardest subject in a physics undergrad degree? Electromagnetism?

>>16770953
Easily thermodynamics. You need a good book/teacher, and there is no book considered to be a widely accepted standard to study from, so there are a lot of ideas and understanding that you may potentially miss. It certainly ain't an impossible subject if you got the right resources.

Undergrad (emphasis) E&M is just a vector calculus class - if you can't do well in it, it means you prob can't do simple vector calc well. And griffiths is the main thing you need, for standard. No book is perfect and some books cover some things he doesn't, but his is quite good.

Easiest is special relativity; one reason why einstein = smart to normies is because his reality-shifting ideas are easily explainable to normies, whereas reality-shifting QM hasn't made dirac a household name.

>>16770996
Where does quantum mechanics and particle physics rank in terms of difficulty?

>>16770953
in mine it was either general relativity or relativistic quantum mechanics

>>16760394
>Usually at the top and bottom parts of life, you learn that there is a simplicity to existence that makes it great...
Midwit answer.

>>16770953
>Electromagnetism?
Probably. It's the first time almost all undergrads will ever have encountered vector calculus and overall it's a marked jump in difficulty from highschool to undergrad level EM.

The math in GR is more challenging but by that point any student should know what to expect.

>>16771003
Undergrad (emphasis) QM isn't actually that hard, on the condition that you're not bad at math+physics. Undergrad QM is a special thing, in that it involves from very brief to very good familiarity of a number of different areas of math: algebra, calculus, probability, differential equations, probability, wave and fourier analysis, calculus-involving-approximations, matrices+vectors, and perhaps linear algebra theory - these are like a sorta progression-of-necessity in my opinion for math. And that's just math; you gotta know a little something about the rest of physics too! Reasonable understanding of the rest of the areas (even a little thermodynamics [and vis versa, in that QM is good for some areas of thermo]) is required. But all of the stuff I mentioned really isn't going in-depth or hard in my opinion. It's also a fun history lesson too! Learn about how the theory was developed, who and what experiments, etc, why do we believe QM to be true today?

>extra ranting
To call yourself proficient at undergrad QM is a different thing. It can only really happen if you've learned about linear algebra theory - and no, I don't mean just cursory linear algebra like matrices and vectors (which still is needed!); I mean if you aren't comfortable talking about Hilbert spaces when it's taught/mentioned in class, I wouldn't say you're proficient at understanding undergrad QM. But undergrad linear algebra theory is really easy so if you want prep, just read something easy like Linear Algebra Done Right (axler), preferably after you know about matrices and vectors in the basic way. Even though it's only on finite vector spaces, it should be easy to translate your understanding to hilbert spaces. It also helps with bra-ket notation.

cont.

>>16771126
So to me, undergrad QM honestly ain't bad if you're well rounded, but to call yourself proficient, you need intro linear algebra theory.
I'm typing this part after. Spin, is like a completely different creature than what I described above (I just forgot about it) and it's gonna be the weirdest new math you see. If you just "go with it", you should be fine. It may be too much to ask of an undergrad to go too deep into understanding spinors or clifford algebra or wtv.

Shankar is a good 2nd book, but griffiths is a good intro (griffiths should not be hard).

>Particle physics
Uh, I don't know how far you're gonna get into Feynman diagrams, but before you get to that, you need a really good understanding spin from undergrad QM, and you need to know some special relativity. Griffiths history lesson is pretty great though. If you're asking about difficulty, it's more like, well in what area?

>>16770953
It terms of like, actual physical work you put in, E&M has like the most math problems they're gonna make you do. Some classical mech problems require a lot of work too, but E&M also requires additional comprehension, so I'll give it to E&M

In terms of like understanding and comprehension, it's gonna be thermo (as I said >>16770996) or QM depending on the resources you have, which includes the knowledge you already know. I might as well just put them as a tie, cause it'd probably vary from person to person.

>>16759536 (OP)
Are there any books I can read that will teach me all levels of math? I want my PhD in Pure Math.

>>16759536 (OP)
I'd explore pink pant's black hole event horizon if you know what I mean.

>>16770538
>300k starting
Yeah ofc I shouldn't have forgotten to mention it.
That said, it barely spread beyond /sci/,
unlike the term brainlet.

>scientifically speaking
I think that scheme existed 10 years ago already

the light cone can be as wide or as thin as you want right? so a light cone that is so thin as to be non-existent means the causal event doesnt exist? and light cone so wide at t=0 that it covers a significant area means its an infinity or singularity?

>>16771220
Nope. It's just a convention depending on how you scale the axes, the most common being light rays travel at 45°. It has no effect on the casual nature of events.

>>16771559
But ultimately you are always limited by the speed of light, there's always going to be events in spacetime that will be causally inaccessible to the observer.

>>16771220
You can make light cones shrink or not if you thinkg of "changing the speed of light." Intuitively, you recover Galilean physics by taking the speed of light to infinity, i.e. all events can influence each other.

Now shrinking the light cones sound like a weird limit: c->0. What happens then? This is known as the "Carrollian limit" and some fun stuff happens then. See this reddit thread for more (yeah fuck you I'm linking to a reddit thread in 4chan blablabla)

https://old.reddit.com/r/Physics/comments/1b7ubfs/

If you buy N lottery tickets in a lottery in which one in N tickets will win, the probability of winning becomes close to 1-1/e as N gets larger which is about 63%.

Why is that counter-intuitive? If one in every 100 lottery tickets is a winning ticket, it feels like you should buy at least that 100 tickets to guarantee at least 50% chance of winning. One in 100 tickets would be a winning ticket on average, but even if you just buy 70 tickets, you still apparently have greater chance of winning than losing despite the fact that it was one in 100 tickets that wins, not one in 70.

>>16771670
pre-empting other people calling you a gigafaggot doesn't in fact make you not a gigafaggot. What c gives us the avengers universe?

>>16771922
C triply bonded with nitrogen

>>16771921
> if you just buy 70 tickets, you still apparently have greater chance of winning than losing despite the fact that it was one in 100 tickets that wins, not one in 70.
You are forgetting about all the other possible outcomes. There is a chance of having 2 winning tickets, or 3, or more. Those probabilities are lower that a single ticket winning but add them all together and you have a higher chance of "winning" than you might expect.

You actually stated this in your question. In that limit 1/e is the probability you have NO winning tickets.

how do i make meth from the ephedra plant

>>16772088
probably some form of recrystallization. its an organic chemistry technique.

You pick three random points inside of an equilateral triangle. What is the probability that the triangle formed, having those three points as vertices, has an angle greater than 90 degrees?

>>16772567
https://math.mit.edu/~edelman/publications/random_triangle.pdf

so the current consensus is that there was rapid inflation first THEN the dark energy densified into a singularity THEN it cooled into the universe we see today? so if there wasnt an initial singularity then why was there a sudden appearance of a compact point of dark energy? where did the dark energy suddenly come from?

>>16773060
>THEN the dark energy densified into a singularity
What?? I don't think you know what dark energy does.

>>16773127
>What happened when inflation stopped?
>The best guess as to what happened (and our equations show this is possible, but don’t tell us the details) is that all that dark energy got turned into particles — including particles we’re made from, and lots of other types of particles we know about, and perhaps lots of particles we don’t know about. And when this happened, the universe became very hot, and very dense — and it continued expanding, though much more slowly.
https://profmattstrassler.com/articles-and-posts/relativity-space-astronomy-and-cosmology/history-of-the-universe/inflation/

>>16773138
The general consensus is that inflation has no relation to dark energy so why that article is trying to link the two I have no idea. It's an extremely out-of-date conjecture that has no supporting evidence so at best it's a fringe idea. Superficially while they both have to do with the expansion of the universe they operate on completely different energy scales and act in extremely different ways - for one, the effect of dark energy in the earliest epochs of the universe was essentially zero.

if deer think tigers are green what do birds see?

I'm having a hard time understanding elementary symmetric polynomials. I don't understand at all the third equality in the image, why the fuck did a 6 show up out of nowhere? Why are there 3 variables in the last term? It's not making sense to me. Is there any book that explains this shit in a very easy-to-understand way?

can i get a handful of your favorite Mochizuki memes?

>>16773595
> I don't understand at all the third equality in the image
I'm not surprised. They have skipped over *many* steps to get there. Either you are meant to use some identities introduced earlier in the text or from a previous Example question, or - as happens a lot in math textbooks - you have to work it out yourself the hard way.

> why the fuck did a 6 show up out of nowhere?
When you expand the squared parentheses you obtain: [math]3\alpha_1 \left[ {\alpha_2}^2 + 2\alpha_2(\alpha_3 + ... + \alpha_n) + (\alpha_3 + ... + \alpha_n)^2 \right][/math], so you end up with a term [math]6\alpha_1 \alpha_2(\alpha_3 + ... + \alpha_n)[/math].

Now you could just keep repeating the process with expanding the new squared and cubed expressions until all you're left with is [math]\alpha_n[/math] terms, but before then you should be able to spot the pattern and rewrite it all with that third equality.

How is [math]x^{\frac{2}{3}}=(x^{\frac{1}{3}})^2[/math] true? Considering that [math]\frac{1}{3}^2 \neq \frac{1}{3} \times 2}[/math], and further [math]\frac{1}{9} \neq \frac{2}{3}[/math]. Yes, I know this is a stupid question. Still.

>>16773822
[eqn](x^{\frac{1}{3}})^2 = x^{\frac{1}{3}} \times x^{\frac{1}{3}} = x^{(\frac{1}{3} + \frac{1}{3})} = x^{\frac{2}{3}}[/eqn]
As for the rest, the rules for manipulating powers are not the same as manipulating fractions.

>>16773847
Thank you. I seriously need to relearn algebra. The expression [math]x^{\frac{1}{3}} \times x^{\frac{1}{3}} = x^{(\frac{1}{3}+\frac{1}{3})}[/math] would have never occurred to me.

What major requires the highest IQ?

>>16773424
i don't know exactly what they see, but birds can see more colors than humans, their sight goes into the uv spectrum.

>>16773873
looks like you need to relearn latex too

i need to get the frequency of an unknown fixed rate clock given a known frequency fixed rate clock, samples from each, and a hopefully negligible amount of error introduced by latency due to distance between each clock
i presume i should gather samples from both multiple times at multiple fixed rates
i have a known frequency value to check the result with at least and i'm fairly certain any unknown value is a power of 2

i don't know much in the way of statistics, i've only taken a basic stats course that i barely remember, is simple linear regression capable of solving this, or at least pointing in the right direction?

>>16770953
We had a course called analytical electromagnetism and it was easily the hardest course in my undergrad. I'm assuming to the rest of the world it's simply known as electromagnetism, not sure what was the point of the name.

According to Wolfram Alpha, it is unknown whether log(pi,7) is irrational. Why don't we know that? Is it possible that seven is equal to pi raised to some fraction?

I'm 2 days into the semester and I already feel like killing myself. No sleep because of social anxiety and 0 self esteem, all the classes are difficult and I feel like the work is going to come in like an avalanche. I'm also on an insane caloric deficit and the only thing I can think about is girls. What the fuck do I do?
Undergrad in EE.
I am absolutely repulsed by how the semester seems like it will go.

>>16774064
nta, he just didn't put spaces before and after both ["math"]s

What's a good way to measure high frequency noises? Can phones detect them well?
Like, could I just record audio on a phone, then upload the file onto a comp and find some software (or write python code) that does a fourier transform on it? Or would I really need to buy some specialized tech for it?

>>16774512
1. Drop the knife or noose.

2. Get a sleep schedule going (or a daily schedule to fit sleep in).

3. Find a tutor, or a tutoring center for your college.
They'll be one of the few important people/friend(s)
you'll make. The earlier, the better.

4. Attend the professor's office hours where possible
and ask questions. Less stressful than saying
silly stuff in class and also another important
person/friend you'll make. The earlier, the better.

5. Eat something substantial for breakfast.
If not then, do it at the first gap between
your courses (daily schedule comes in handy).

6. Don't worry about girls, that's your biology
yelling for stimulation. Focus on your work,
and find one guy that will fill you in if you
miss class (another one!). If you've been
practicing, you can help someone out with
questions [hint: this is one way to get girls ;) ]

7. The daily schedule is supposed to get you
into the habit and remind you of things.
You stray from that and you'll be lost.
Be flexible when necessary, you only got
24 hours to a day.

How's that? Any questions?

>>16774340
We have to assume software limit; knowing whether something is irrational in base π requires either math or compute, and since compute is finitely rational we cannot use the latter.

Solving the former would mean having stable convergence if I have the research right

>>16774142
I wrote a bunch of stuff but deleted it accidentally so in short: yes.
Just sample a bunch of times to get data [math](t^k_n,t^u_n)_n[/math] of (known, unknown) clock tick counts, and with frequencies [math]f^k,f^u[/math] I'd expect a relation like [math]t^u_n = \frac{f^u}{f^k}t^k_n+\text{const}+\text{error}[/math], so just regress [math]t^u[/math] on [math]t^k[/math] to get the ratio and then scale by your known frequency.
If anything, sampling at fixed rates might introduce a bias; for linear regression you just want independent samples to keep it simple.

Is there a formal proof for the first assertion? I lack the geometrical background to get this argument at first glance.

I need to get 22,000 results from google scholar, how do I do it?
scholarly doesn't work at all it just gets me ip banned

and i think it only shows the first 1000 results?

Have we figured out how consciousness works yet? In 50 years can I upload my mind to a computer for pseudo immortality?

>>16774984
No to both questions. Both are such incredibly hard problems you are looking at closer to 500 years, not 50, if it's possible at all.

>>16774989
Figured, all the cool shit is way out of our lifetimes

>>16769805
>it could be turned into pure energy and it would still curve spacetime.
what keeps the pure energy bound together so tightly?

Do higgs particles or gravity waves escape the event horizon, or is are inside the event horizon cut off from the rest of the universe due to space time being bent around in a circular shape so there is no in or out path possible?

>>16775091
Anything inside the event horizon remains inside the event horizon.

>>16774524
Check the microphones' gain through the frequencies you're interested in. Ex https://www.researchgate.net/figure/A-typical-frequency-response-curve-for-a-microphone-Note-that-for-some-frequencies-the_fig1_264558809
Also the biteate needs to be high enough, otherwise the high frequency information is lost (Shannon's theorem).

>theres a particularly cold area of space thats a mystery
if temperature is a phenomenon of how fast particles are moving and space is a vacuum, how can there be more cold than absolute zero

>>16775250
I presume you are talking about the CMB cold spot. It's not colder than absolute zero, instead it is something like 100 micro-Kelvin colder than the average CMB temperature of 2.7K - so you're talking about a tiny difference.

so what's the point of logarithms? but every video about their usefulness is basically
>before modern calculators, this was how we did multiplication of large numbers
i get that there was a period of 300 years where a slide ruler was a useful tool to know how to use, but that's basically pointless now.

Fghgg ghhff ggffg [math]\pi\int\Sigma{lSf}\circlearrowleft \\
[/math] ghggh hffgg hgghh

Tggg ggff kooj [eqn]\pi\int\Sigma{lSf}\circlearrowleft \\
[/eqn] gjhfg hgfgv fsdff

[math]\nexists[/math]

Can someone explain this s*it. Light, or in other words photons have no mass. That's why they're able to move at the speed of light because mass could never move that fast.

But if a massless object bumps into something it doesn't exert a force because for that you would need mass. Without mass you have no momentum and no kinetic energy. And yet a solar sail is a thing that apparently works by photons pushing it forward like wind pushing onto the sail of a sailboat. How is that possible?

>>16776089
>Without mass you have no momentum and no kinetic energy
That is what you are taught in highschool. Like much of physics you are told at that level it's either not true or incomplete.

The relativistic energy momentum relation, which applies to all particles, is given by [math]E^2 = (p c)^2 + \left(m_0 c^2\right)^2[/math]. So for massless particles [math]m_0 = 0[/math], but they still have a momentum given by [math]p = E/c[/math].

>>16776093
Is it possible to calculate with that how much newtons a square meter of sunlight is pushing?

>>16776117
Sure. You could use the Sun's luminosity to calculate the amount of energy passing through an area at a given distance. You could then convert that into photon momentum.

>>16775595
exponents have the property that f(x+y) = f(x)f(y) and logs have the property that f(xy) = f(x) + f(y)
any area where exponents are important, something can be said about log

>exponents generate changes in a calculus way and are thus vital to calculus from that rule, and logs are their function inverses which make them vital too
>thermodynamics use that property to define entropy
>to show that a data set is exponential, you can use log to see how linear your new data set is, and the closer it is linearity, the closer the original data set is to exponential

for every useful function, their inverse can be useful too

>>16774814
Literally how radians are defined. All circles have circumference 2*pi*r, so measure the length as you move along a circle is gonna be proportional to radius, r. For example, walking around half the circle is half the circumference, so (1/2)(2*pi*r). Since this is so simple, might as well use units of angle and length where 1 radian corresponds to 1*radius length, 2 radians is just 2*radius length, and 2*pi radians is the entire circumference - the overall relationship being r*(theta) = length as you walk around a circle, called its arc length.

>>16774814
And the area of a circular sector is θ*r^2/2. The image is a derivation or proof.

What is the probability that a rain drum would play Mary Had a Little Lamb?

the single thread performance (STP) of a multi-core CPU is the performance of the fastest core on the die.
the STP of an 8-core CPU is 1.3% lower than the STP of a 12-core CPU with an identical die.
assume the performance of each core is independent.
assume the distribution of core performance is normal.
what is the standard deviation of core performance?

Does 49 to the power of an odd number always end with 49?

What is the N:th number which, when raised to an odd power, always ends with the same number?

For example, 49^k always ends with 49 for all odd k. Same with 76, for example 76^5 = 2535525376. The first five numbers in the sequence are 1, 25, 49. 76 and 99 according to chatGPT.

Is there a way to determine the N:th number?

What is the N:th number which, when raised to an odd power, always ends with the same number?

For example, 49^k always ends with 49 for all odd k. Same with 76, for example 76^5 = 2535525376. Some of the first numbers that have this property are 1, 25, 49, 51, 76, 99, etc.

Is there a way to determine the N:th number?

>>16759536 (OP)
What is exactly the cross curvature in the Hessian Matrix? I can't manage to imagine the effect on a plot like I can understand how a curvature in an axis can counter the curvature of an other axis because they are, for example, symmetric eigenvalues.

>>16776093
So when we are hit by sunlight it's pushing us?

>>16777397
Yes, but the amount of force is so small we will never feel it. That is why light sails are designed to be very light and have huge surface areas.

>>16777242
it's studious kitty

1st: 1*5^0 + 0 = 1

2nd: 1*5^1 – 1 = 4, 1*5^1 + 0 = 5, 1*5^1 + 1 = 6
3rd: 2*5^1 – 1 = 9

4th: 1*5^2 – 1 = 24, 1*5^2 + 0 = 25
5th: 2*5^2 – 1 = 49, 2*5^2 + 1 = 51
6th: 3*5^2 + 0 = 75,3*5^2 + 1 = 76
7th: 4*5^2 – 1 = 99

8th: 1*5^3 + 0 = 125
9th: 2*5^3 – 1 = 249, 2*5^3 + 1 = 251
10th: 3*5^3 + 0 = 375, 3*5^3 + 1 = 376
11th: 4*5^3 – 1 = 499, 4*5^3 + 1 = 501
12th: 5*5^3 – 1 = 624,5*5^3 + 0 = 625
13th: 6*5^3 – 1 = 749,6*5^3 + 1 = 751
14th: 7*5^3 + 0 = 875
15th: 8*5^3 – 1 = 999

center(t) = (t – 2^F + 1)*5^F
F = Floor[Log[t]/Log[2]]
t = batch

>>16777460
>6th:
3*5^2 + 0 = 75, 3*5^2 + 1 = 76
>12th:
5*5^3 – 1 = 624, 5*5^3 + 0 = 625
>13th:
6*5^3 – 1 = 749, 6*5^3 + 1 = 751

>>16777242
I don't like this problem. It's ugly.

>>16777242
https://oeis.org/A033819

>>16777469
Sorry for that. I will come up with better problems in the future