/sci/ - Science & Math

old thread: >>10473981

>>10500889
Why would you link to the previous thread in a containment thread?

10500954
kys

You guys are smart here, right? How can I, a guy with just a GED who hasn't done a math problem in 12 years, get a guaranteed million dollar+ lottery jackpot tomorrow? There's a formula for that, right?

Why /sci/ hates software engineering?

Are niggers human?

>>10501047
maths fags think coding is trivial and beneath them because they only get exposed to babby tier programming problems when doing their maths rather than having to make professional tier software

>>10500954
in case anyone wants to answer a previous question, to get there faster, or ask a followup to an answerer

>>10500954
That's common practice among this type of threads, are you a newfriend?

>>10501103
THIS. I'm EE, we did a bit of coding in java, embedded C, assembly, VHDL, nothing at all taxing but even that was miles ahead of anything maths were doing, but absolutely nothing compared to what CS and the actual programmers were doing

>>10501103
>comp fags think math is trivial and beneath them because they only get exposed to babby tier calc problems when doing their maths rather than having to take actual math classes

>>10501163
Can you be a seasoned programmer while being EE?

I know nothing about grad school but I'd like to get a masters in the future
as an undergrad sophmore knowing nothing about grad school, how does the process of applying and getting in work for your average grad school?

>Leibniz thought of the integral as an infinite sum of infinitesimal summands.

what does this actually mean

>>10501124
Neither of those cases make sense when people already quote the post for clearness.
>>10501129
It's common practice in generals. Of course, some containment threads masquerade as generals, such as /eng/, but /sqt/ is very explicitly a containment thread.

>>10501171
Absolutely, a frien... well, an acquaintance from uni went pure programmer during his degree then went into industry as a programmer afterwards. A good friend from the same uni pretty much does programming all day as part of his job and is better than most of the pure CS guys I know, he was EE with a speciality in mechatronics. Then there's me, EE with a speciality in embedded system design, I fucking despised programming so much I left the industry and joined the merchant navy as a mechanical and power systems engineer. So yeah, it absolutely can happen, really depends on the person.

What are some arguments against the statement that math and physics and human inventions?
I would personally support it by saying that:
1. Pure mathematics and axioms and ways to represent basic real life situations with internationally understood notations in order to solve problems that would not be solvable without them.

2. Some other life form with an intelligence >= to that of humans could have developed other notation in order to solve "their" personal problems.

Then again, it all comes down to your definition of "mathematics" I guess. One could say that it is notations and numbers which would obviously lead to the conclusion that it is invented as "1, 2, 3, ..., 100" are completely arbitrary by nature.

Why was L'Hôpital's last name "the hospital"? That seems like a weird name

>>10501183
(Assuming the one dimensional case
The definate integral is the area under a curve, yes? Let's say that curve is represented by a function f(x), so the integral is the area between f(x) and the x axis, bounded by the limits of integration, x=a and x=b. Between a and b, split up the x axis into mant little piece, let's say there are i many pieces, with each one called Δxi. The area for each chunk is then f(xi)*Δxi. So, the integral (area under the curve) is approximately Σf(xi)*Δxi

Literal 2nd grade stuff but why is it that the moon is brighter when it's away from the sun?

I know that it always has a bright side, but I'm guessing we see more of it at night when it's away from the sun(relative to your current location) because, at night, you're facing away from the sun so the moon is closer to you. Am I right? or am I missing something?

>>10501540
also I'm assuming that if the moon is closer to you and you see more of it then it appears brighter.

>>10501540
what do you mean by brightness (lumen, meaning how much light per area -- or candela, amount of light total -- or how bright in comparison to the background)?

>>10501540
it's just as bright it just looks brighter in the dark

>>10501560
Relative to the background yeah. How bright it is compared to you, waxing/waning, I guess.

>>10501589
turn on your smartphone flashlight in a dark room and it looks bright as fuck. turn it on outside in broad daylight and it doesn't look that bright. it's relative and your eyes adapt.

>>10501540
The moon is brightest during the full moon phase, which accurs when the earth is approximately between the sun and moon. This is when the angle of reflection of the sun's rays off the moon to our eyes is approx zero. New moons occur when the sun is behind the moon relative to us.

Does anyone have that image of a poorly drawn smug face on Paint, white background, where it says something like
"huh i see you made a spelling mistake so instead of attacking your argument i will point out the flaw in your grammar, case closed"

Why do they still say that Riemann hypothesis is unsolved? It is negated since last year.

>>10502159
[math]\widehat{\text{ok bud}}[/math]

What is the most probable solution to the Fermi Paradox?

I personally think it's one of these two:
1. We're a simulation and the simulators decided we'd be the only life forms in it.
2. A group such as the jews come into existence in each civilization, inevitably resulting in that civilizations collapse.

>>10502173
1) simulation """"theory"""" belongs on /x/ or reddit
2) jews actually advance civilization

In a 100 level physics lab manual I have, they assert that mΔv=1/2*m*g*T for an person jumping off and landing on a force plate, where T is time of flight. This is incorrect, and it should just be m*g*T, right? Or am I having a stroke?

>>10502215
>2) jews actually advance civilization

>>10502229
>honk posting
>>>/b/

>>10502233
Two of your posts so far has been telling people to go to other boards. Do you not cringe at your own pretentious behaviour?

>>10502220
Wtf? Post the context? sure it isnt deltaX?

>>10502240
Nah

>>10502220
>>10502246
Also, "jumping off" from that same plate? Then of course T is the time from ground to apex and back again, so of course only T/2 is movement downwards.

>>10502253
I figured it out. It's for an impulse-momentum lab where they calculate impulse of the jump, impulse of the landing, and change in momentum during their time of flight. The 1/2 stems from the fact that ΔV is from zero (standing) to their initial velocity (jumping), while I was treating it as initial velocity (jump) to final velocity (landing).

>>10502252
You're probably jewish then, considering this amount of chutzpah

>>10502268
How flattering, but I am not one of God's chosen

>>10502290
>How flattering
No it really isn't

>>10502290
>how do you do fellow white people

>>10502302
>he doesn't know

reposting
>A or B?

>>10502415
if you dont explain your notation, im not going to make the effort

>>10502415
A

Is asteroid mining a meme or what?

Would it be a mistake to pursue a career in space resource mining, like studying Space Resources at the Colorado school of mines?

>>10502415
Flags only deploy if there is a force on them. The airplane is not accelerating, so there is no inertial force. There is only the drag force from the air. What direction is the air moving? The answer is A

>>10502516
Yes it is, to both questions. We are a thousand years out from asteroid mining being a viable operation.

>>10502173
men develop brains capable of abstraction in order to solve problems and become the smartest ape on their planet
that very abstraction ability which let them solve intellectually difficult problems lets them enjoy anime more than 3D whores and the birth rate plummets

>>10502539
That's what I thought

>mfw

>>10502576
Major in geology or mech e or something, anything is better than that

>>10500887
Why is stupidity the eternal construct while intelligence is not?

>>10502581
Based schizophrenic retard

>>10502501
>>10502528
thank you, I can't believe I spent an hour arguing about it at work with a phd in physics who said B

>>10502471
what is there to explain, all the velocity vectors are clearly labelled

>>10502581
entropy

>All wuzzalumps are woozles. Not all woozles are necessarily wuzzalumps.
Explain this shit to me.

>>10502754
all stormfags are feds. not all feds are necessarily stormfags.

>>10502754
The converse of a statement is not the same as the original statement.

>>10502754
all whole numbers are real numbers
not all real numbers are necessarily whole numbers

>>10502681
>phd in physics who said B
jesus christ, how embarrassing

>>10502754
All dollars are monies (US, Canada, Liberia...)
Not all monies are dollars (Euro, Peso, Yuan...)

>>10502605
Self-reflective friend inclusion BEEEAAAAM!

>>10500887
why do i like waffles more than pancakes

I got a stupid question. how do learn algebra? I wanna work as an electrician. but I've failed math from K-12 literally every single grade I failed math. had to drop out despite passing everything else. went to college math prep classes for GED and failed all those. failed GED math test 4 times before they lowered my score cause they felt sorry for me so I could pass. should I just kill myself because I'll never get a get a real job that pays? serious question.

>>10502681
>what is there to explain, all the velocity vectors are clearly labelled
well to be honest i thought you wrote down "flay" and i didnt know what the fuck that was

>>10503547
khan academy ad nauseum

>>10503571
okay I may be shit at math but that wasnt grammatically correct. i think you wanted to say Khan academy. you make me sick. but you just said Khan academy makes me sick.

>>10503601
i meant KA until it makes you sick

How do i prevent them from coming for me?

>>10503608
>Implying we're not already there

>>10500966
Based

>>10501103
This reminded me of an accountant who thought electrical circuits were easy because he had only done highschool physics.

>>10502173
Space is much bigger than the average person realizes.
The speed limit makes its very improbable for comms between stars, so picking up a stray signal is astronomically rare.
Space travel takes tens of thousands of years to become economically viable, and some civilizations may robotize space to feed their energy requirements instead of expanding
The idea that a civilization could colonize the Galaxy in a short period of time makes a lot of assumptions about the economic systems of such a civilization, I think the estimate is inaccurate.

I have an offer for a PhD lab. University of Melbourne, $56,000 AUD yearly (tax free) plus 6 months at a lab in Yale. Lab head would be director of the research institute. They are very, very well connected.

BUT.
I do not love the topic. Is this a problem? Do you need to love your project?

The money is great, the connections are great, and there are research assistants and support facilities out the wazoo to do all the tedious parts for me.

The project has some interesting parts from an evolutionary genetics perspective, but it also dips into exercise science on occasion- an area that I have less than zero interest in.

How do I rationalise all this? Do I say no, and keep looking for a different project somewhere else that aligns better with my interests? Can I even really know what my scientific interests are at this stage? (Mid-20, Hons. degree in biomed sci)

Is the most important thing in your Phd just to be strategic, well connected, and have an easy life and money?

>>10503774
do what u want to do for career in postdoc

i did my perfect project for phd and now i need to find a postdoc and no one else works on this topic (in microbiology). most postdocs will keep working on what they did in postdoc if they become pi. u can pivot halfway thru postdoc and do your best to make that ur perfect career topic but its hard and you need to have had a successful project already (basically you have to have gotten lucky)

during phd get ahead as fast as you can. science is slow as all fuck and you can beat out others for awards/fellowships by just choosing project directions that are quickly successful (join onto something which is already working, stuff like that)

t. 6th yr phd

I want to make an airship and live semi-permanently in it. I'm not a scientist or engineer or know anything about building stuff. I guess building it myself might be a bad idea, so how possible would it be to have one custom built for me?
I've researched them a little bit and:
- I think hydrogen would be better than helium, as I wouldn't mind dying and wouldn't pose a risk for other people. Helium is expensive and can't carry as much weight.
- I don't like the idea of running oil-based engines. I've seen some ultralight planes are powered by electric motors. Do you think a mix of solar and wind/turbines could store enough energy to slowly move around? Would the batteries weight too much? From what I've seen turbines are less efficient and burst up in flames every now and then, it's a bit scary.
- Apparently "passive atmosphere water generators" exist, so I could get free water from the air. Not sure about the quantity, though. Would 2 liters a day be possible?
- I don't think growing food would realistically be possible, so in that sense resupplying at least in that regard would be needed.

>>10503848
>how possible would it be to have one custom built for me?
That's not a science or math question, and best directed at a manufacturer. I don't think it is impossible for you to have somebody make you another Hindenburg provided you have the money, but I'd doubt that you would receive FAA clearance to fly it anywhere.

If I draw a point with a bunch of lines radiating away from it, they spread apart. So if someone was standing a long way from that point, they probably won't get hit with one of the lines.

But if I consider those lines to be photons radiating away from a star millions of light years away, then no matter where I am, I'm guaranteed to receive photons from that star. Despite being "points" they don't seem to separate out with distance.

I guess that's where the wave concept takes over, in that the "light waves" emanate outward in all directions. But that implies an infinite number of viewers around the star will see the light from it. If each photon carries energy, doesn't that imply either 1) some people won't see the star, or 2) the star is radiating infinite energy?

Can the Betti numbers change if you take the homology using coefficients from different fields?

>>10504085
Yes, real projective space for instance.

>>10503921
First of all, read https://physics.stackexchange.com/questions/87986/photons-from-stars-how-do-they-fill-in-such-large-angular-distances
The gist of it's is that
1) The amount of photons released by a star is way more than you and I could ever begin to comprehend, so it IS likely that you perceive a few (actually a lot) of them, at a given distance from Earth (so there are a lot of stars you actually can't see for this reason).
2) Going a bit more into detail, you are interacting with a field and excitations in it, instead of individual objects. So comparing the path of a photon to a straight line may make things a bit more confusing.

>But that implies an infinite number of viewers around the star will see the light from it.
You are making the wrong assumption that it is possible to have infinity viewers in the first place. It's hard for me to say for certain what the exact threshold is, but if your viewer were at least a Planck length worth of space or smaller, observing a photon theoretically shouldn't be possible (because the uncertainty principle would mess up the experiment). Since the length is above zero and not an infinitesimal, it is not feasible to surround a star with infinitely many viewers, without being an infinite distance away from the star.

>>10504137
Thanks, and of simplicial complexes?

Lads, what's the dryest, most autistic econometrics text known to man?

With the assumption n not equal to 0, how do you get from the top integral to the bottom?

I have the following data for tournament brackets:
>Actual seeding of a player
>Predicted seeding from a program
>Final result/placement of a player
What statistics can I derive from this and how would I go about it?

>>10504222
just calculate it

say I have an expression (specifically, x=cosh(y))

how would I determine what modifications would make said expression intersect a specific point (specifically, (1,1))

>>10504222
Not exactly a difficult integral. Obviously just parts twice til you get the same integral on the other side.

>>10504298
?! Is this homework? What do you mean by "modification"?
Here's one: [math] x = \cosh(y) - \cosh(1) + 1[/math]

What are some actually useful prerequisites for Spivak or Apostol? I already took a course in calc. Should just some intro to proofs book be good enough? I was thinking about also reading a book on logic and set theory but that just feels like overkill

>>10504332
You can't answer the question without knowing what your ability is. Why don't you just go through the book and see where your weaknesses lie?
"All this is [book] good" talk, I don't understand it. The mathematics don't change. You learn the methods and concepts by applying them. Just go do it.

Given that ADB is a right angle and BC = BD, and given the angles a and b, what is the angle c?

>>10504332
>I already took a course in calc
Then why are you repeating yourself? An analysis book will have all the proofs you've missed and more.
> Should just some intro to proofs book be good enough? I was thinking about also reading a book on logic and set theory but that just feels like overkill
That's a good idea. Set theory is good practice after proof course. I would recommend you do a rigorous linear algebra book after that.

>>10504339
I tried reading Apostol but the first three chapters were just too hard for me because I didn’t know shit about proving stuff. This was also a year ago so I haven’t tried reading it since. I know basic logic stuff like propositional and predicate logic, inference rules, and some simple set theory. Proofs I don’t really know other than knowing how if then statements are proven but that’s about it

>>10504348
>BC = BD
>radius = radius
wow. now what? Are you sure you typed that in correctly?

>>10504365
>i know “logic” but can’t understand hs level analysis
what did he mean by this?

>>10504172
nigga projective space is (homeomorphic to) a simplicial complex

This is probably very retarded but the book says: "the hessian matrix has negative determinant so the point is a saddle point"
Why? Usually I calculate the eigenvalues of the hessian matrix (in this case i would expect negative and positive values), but this seems to be a faster method based on some rule i don't know about

>>10500887
what's 1+1 equal to ?

>>10504399
The determinant is also known as the product of eigenvalues.

>>10504399
Write down the Hessian for a f: R^2->R^2 function and stare at it.

>>10504387
It means I learned some stuff in the year since I read Apostol, but I’ll read it and see if it makes more sense to me now.

Explain how I get cross product from parameter form.

>>10504467
Parameter form of what? Be a little more specific. Write one down.

>>10504499
Of planes with vectors and schtuff
[math]x=2-7s+1t, y=-3+4s+4t, z=9-2s-8t[/math]
I want to understand how I get the one function that's 90 deg from both vectors and describes the entire plane

>>10504396
My bad I should have added I meant finite simplicial complexes, Do you happen to have a reference on what exactly changes as the coefficient field is changed?

>>10504511
Come on, this is middle school stuff. Just write down the vectors

[math] \left(\matrix{x \\ y \\ z}\right) =
\left(\matrix{2 \\ -3 \\ 9}\right)
+ s \left(\matrix{-7 \\ 4 \\ -2}\right)
+ t \left(\matrix{ \text{your} \\ \text{work} \\ \text{here}}\right) [/math]
and then, if you don't know what to take the cross product of, ask your school counsellor.

>>10504534
Yes, any book on homological algebra or algebraic topology.

The thing that changes is the Ext and Tor terms, the first for cohomology and the second for homology. Ext is a bit easier to understand but requires cohomology. Google the universal coefficient theorem (which exists for both).

>>10504534
>>10504551
also RP^2 is a finite simplicial complex and can be triangulated similar to the torus

>>10504553
>>10504551
Thanks!

>>10504511
> x=2-7s+1t, y=-3+4s+4t, z=9-2s-8t
IOW:
[x,y,z] = [2,-3,9]+s*[-7,4,-2]+t*[1,4,-8]
=> P = O+s*U+t*V where P=[x,y,z], O=[2,-3,9], U=[-7,4,-2], V=[1,4,-8].
The implicit form is N·P=N·O where N=U×V.
N=U×V = [(4*-8)-(-2*4),(-2*1)-(-7*-8),(-7*4)-(4*1)
= [-32+8,-2-56,-28-4]
= [-24,-58,-32]
N·O = [-24,-58,-32]·[2,-3,9]
= (-24*2)+(-58*-3)+(-32*9)
= -48+174-288
= -162
=> -24x-58y-32z = -162
=> 12x+29y+16z = 81

>>10504310
No, we're about to start Sequences and Series in Calc II.

I was fucking around with an online graphing utility, plotting the Harmonic Series and trying to approximate it.
I noticed that x=cosh(y) approximates it very, very well. I want to find the iteration of cosh(y) that matches the harmonic series as best as possible, and I want to start by making cosh(y) intercept the point (1,1).

By modifications, I mean transformations and combinations of coefficients to the variable and the function itself.

What is the ncosh(ny) or ncosh(y/n) that maximizes the approximation?

I guess I could try and do something like find the area between the two functions, and then change cosh(y) to minimize that area. I'm just wondering if there's a more rigorous way with which to do this.

>>10500887
Why do some infections start off with vomiting and then proceed to do completely unrelated things for the rest of the time?

>>10504661
I'd like to answer the question, but unfortunately it is too difficult to understand what you are talking about.
>plot the Harmonic Series
You mean, plot 1/x ?

>x=cosh(y)
you mean y=-Arcosh(x) ?

>approximates it very, very well
Show a picture?

>maximizes the approximation
maybe you mean "minimizes the error" ?

I mean look, 1/x and Arcosh(x), also known as [math] \ln(x+\sqrt{x^2+1}) [/math], won't ever be good approximations of each other.

>>10504710
You phrase that as if the virus or bacterium cause the vomiting directly, instead of the purging of the stomach being a reaction of the immune system.

>>10504717
So why does the immune system do it for things like strep more often than for things like the flu?

>>10504716
Let me try and phrase it another way.

With standard elementary calculus, you integrate and differentiate a function to see how it changes with respect to something else.

I guess what I want to do is keep x constant, and instead treat the entire function itself as a variable. Then by changing the coefficients and other properties of this new function-variable, see how that changes the behavior of the function.

We could take this function-variable and another function, and calculate the area between the two using some sort of integration. Then, it stands to reason, that a certain iteration of that function-variable will yield the least area between it and the static function on an interval. Then, whatever that iteration is, could be said to be the best approximation of the static function that could be achieved with whatever the underlying function was.

Is x^2 ever going to approximate ln(x) very well? Of course not, but that doesn't mean there isn't some variation of x^2 that is the best *approximation* of ln(x) on an interval. It'll just be a really fucking shitty approximation.

>>10504414
>>10504417
Thanks

>>10504790
You still haven't posted a screengrab of that approximation you called "very, very good".

So you want to approximate 1/x by something involving Arcosh(x), at x=1? Go do it, then. I don't see what your question is.

>>10503566
oh shit sorry it does look like a y

>>10504809
he means the x th partial sum of the harmonic series = [math] H_x [/math] the x th Harmonic number
>>10504790
[math] H_x [/math] ~ [math] ln(x) [/math] since [math] H_x - ln(x) [/math] approaches gamma
and [math] arccosh(x) = ln( x + \sqrt{x^2 + 1} ) [/math] ~ [math] ln(x + \sqrt{x^2}) = ln( 2x) = ln(x) + ln(2) [/math]
so [math] arccosh(x) [/math] ~ [math] ln(x) [/math] also
and [math] arccosh(x) [/math] ~ [math] H_x [/math]

>>10504809
pic

>>10504847
I guess when you look at the definition of arccosh it makes more sense.

I've been searching around, is what I described related to the "Calculus of Variations"?

>>10504809
even at large x the error is only about 1%

>>10504878
calculus of variations is way too advanced if youre in calc 2
this is just finding approximations
but just stretching or shifting cosh will not get you the partial sums of the harmonic series

>>10500887
If a black hole has a Schwarzschild radius of [math]R_s[/math], what is the volume of a black whole? i.e. how much space in cubic meters lies beyond the event horizon?

>>10504908
According to my amazing wikipedia technique, you can only calculate the volume from the Schwarzschild radius if the no hair theorem is true, and furthermore they have equal angular momentum and electric charge.
See: https://en.wikipedia.org/wiki/No-hair_theorem

>>10504921
Let the back hole be non-rotating black hole with zero angular momentum.

>>10501042
>assumes we're smart

>>10500887
Hello,

Multiplication is distributive over addition:
a(b+c)=ab + ac

What would it look like if addition was distributive over multiplication please?

>>10505464
a+(bc) = (a+b)(b+c)

>>10505466
Thanks!

And what is the explanation behind the fact that:
(a+b)(c+d) = ac + ad + bc + bd
but:
(a+b)*(1/(c+d)) =/= a/c + a/d + b/c + b/d
please?

How do I use this equation? I'm trying to do a problem where I'm given H' (a scalar, not a matrix), and I'm trying to find the perturbed energy, but I don't really understand it. If H' is a scalar, how do I use this equation?

What are the chances of me discovering something unknown or new to man if (or even if I'm not) looking for it?

>>10505493
in (a+b)(c+d)
(a+b) is just a number, so we can distribute it
(a+b)c + (a+b)d
and distribute again
ac + bc + ad + bd

in (a+b)(1/(c+d))
a/(c+d) + b/(c+d)
but division doesnt distribute
a/(c+d) =/= a/c + a/d
just plug in 1 for every variable to see that it doesnt
1/2 =/= 1 + 1 = 2

>>10505532
Thanks!

is it possible to extract images from human memory, in theory at least?

Is there a sense to finish the education, if you were never able to work for the better mark than C? I have been C-student for my whole life, and at the same time I was not that party-boy, quite the opposite. I hate "Cs get degrees" the platitude, since marks are almost always the litmus test your performance at the job. It happened that I fail or underperform both at the university and the job.

>>10504157
Thanks cobber

>>10505823
not with current technology at least

What's the correct answer?

>>10505936
The answer is what you are for not know the answer

>>10505936
What is basic deduction?

>>10505936
it's a joker. there are three cases.

1. it's a knave. in this case the knave must live and therefore cannot say they are a knave (because that's the truth)

2. it's a knight. in this case the knight must tell the truth and therefore cannot say it's a knave (because that's a lie)

3. it's a joker. jokers can say anything.

Probably the dumbest question on this thread, but why does the Earth revolve around the sun. I mean if gravity acts and both are mutually attracted why don't they just collide. Same wth the moon and other planets.Why does this happen?

>>10505936
a nigger

>>10505951
Think of it like a coin spinning around a vortex funnel thing, even though gravity is pulling the coin inwards the coin comparatively has a lot of inertia. Here's a little thought experiment, think of how far you can horizontally throw a baseball before it hits the ground due to gravity. Now imagine throwing it further and further to the point that the curvature of the earth starts to matter and gives you even more distance (because the ground is dropping off as it travels). At some point, the ball will have enough energy to reach all the way around the planet in orbit. What happens when you give it more or less energy than that?

>>10505951
at the begignigs, everythings was random :DD, the earth proved to survive, but it will collide after enough time

>>10505951
If you have two stationary objects in an empty environment, they will move towards each other because of gravity and eventually collide. Now assume one is fixed in place, and the other is moving in a direction perpendicular to the line joining them. The second will feel a gravitational pull and start turning. The angle of the turn will be larger or smaller depending on how fast it was going (imagine driving a car). If it was going fast enough, it will turn at a smaller angle, and it will not hit the fixed object. But now it's moving away from it, so the same process happens, over and over again. If the moving object was going at the "right" speed, this process will go on forever.

This is sort of how the Earth-Sun system works, but a bit less perfect

>>10503547
You don't need a whole lot of algebra to be a good electrician. That said, your local community college can get you up to speed cheap, and you can take the remedial math courses while doing your electrician classes and labs.

t. Technician who was bad at math and did something about it

>>10505951
If the forces acting on a body are always toward a fixed point, then its angular momentum relative to that point is conserved. If the distance between two bodies is zero then the angular momentum of the first relative to the second is zero. From the first point, the only way that can happen is if it never had any angular momentum to start with: if it was stationary or if the two bodies were initially travelling directly toward each other. If their relative velocity has any tangential component, it will always have a tangential component, i.e. they will orbit each other indefinitely.

What's the connection between flux and volume? How do I show for a region in [math]M\subseteq \mathbb{R}^{3}[/math], that [math]\iiint\limits_{M}dV = \frac{1}{3}\int_{S}F\cdot dS[/math], where [math]S=\partial M[/math]

>>10506045
Divergence theorem

>>10500887
what would happen if I ate pure aluminium?

>>10506010
Let m1= mass of sun, m2= mass of Earth. R= Distance between the sun and the Earth. v= velocity of earth perpendicular to the line joining the Earth and sun.
Then is -G(m1)(m2)/R=(m1)(v^2)/2.
I'm pretty sure this is wrong. Also the distance between the Earth and Sun doesn't remain constant, so how does it work?

>>10506097
>This is sort of how the Earth-Sun system works, but a bit less perfect
Obviously, the sun isnt fixed, and the earth creates an attraction force on the sun, but it is for all intents and purposes negligible.
In fact, it is well known that the sun-earth system forms an ellipse, with the sun at a focus.
>>10506097
>-G(m1)(m2)/R=(m1)(v^2)/2.
equating random energies doesn't tell you anything unless you know what you're doing. In this case, in the perfect system i described it means precisely the perfect speed at which the earth needs to be going at to be in orbit permanently. However, that's the speed of the tangential component of velocity at that instant and not the acceleration created by the gravitational force

>>10506108
any takers?

Why does the fourier transform sometimes have a normilization factor and other times not?
i.e 1/2pi or some time 1/sqrt(2pi)

>>10500887
In the time of chimpanzees i was a monkey

>>10502159
You don't fool anybody, especially since each of your images has the same file name form. At least you know enough to keep your drivel contained in /sqt/

>>10500887
What does the straight line mean? How should i interpret this sum?

>>10506156
it means you are gay

>>10506156
Conditional expectation. Look it up

>>10506132
plox

>>10506119
Use as basis the parametrization of the ellipse, and for each point the line segment between the ellipse and the plane z=2.

>>10506221
It depends on the interval in which the function you're transforming is not zero. Show examples to clarify what you're looking at.

>>10506254
pls explain i am dumb

>>10506193
Ok thank you.

I'm back again. What does this mean? My interpretation: s and a sampled from rho's nipple, where s-prime is sampled from enigma.

s, sprime and a are known, like defined. rho, nipple and enigma aren't, unsure what they are.

>>10506261
Show an example of each, then we can talk about them and why those factors are there. In the meantime, think about the units in which the two functions (original, and fourier-transformed) are expressed. The [math]2\pi[/math] is just part of angular frequency: 2 pi radians per second, for example.

Can someone help me solve this?

What I did was equate kinetic energy before the impact to energy lost to friction (ft*L) and KE after the impact. But it's wrong. Also, I've then tried using the velocity vectors parallel to the displacement vector to calculate the KEs and the result is still wrong. I get a bout 20kN of resistive force.

But I should be getting 9.46*10^7N. That's the actual solution given by my prof.

Can anyone chime in? I haven't been given the coef of fric so I doubt you solve this any other way but through energy.

My math/physics knowledge only reaches high school level.
Black holes seem to be being portrayed like pic related as of lately. My first contact with that kind of depiction was the Interstellar film, but you can also see them elsewhere.
The rings of light they have around them have this unique shape. It's like they have two rings both of which start in the same plane, as in Saturn or whatever but then one curves upward and the other in the opposite direction.

Is this supposed to be a realistic depiction, according to what we know so far? Or is it just used because it looks very pretty and unique?

I'm trying to learn reinforcement learning (and have asked some questions in this thread prior), currently diving balls deep into dynamic programming in order to truly understand what the fuck is going on.

But this very basic recursive concept keeps popping up and i just can't make sense of it (pic related). Doesn't this become infinitly recursive? I mean you're trying to predict the state S using f(S), but the only way of doing so is by predicting f(S') by itself using the subsequent state S'', which needs f(S'''), which needs [math]f(S^{(4)})[/math] and so on.

>The problem of solving the DPFE for f(d1, . . . , di−1) depends upon the subproblem
of solving for f(d1, . . . , di).

How can this even be possible? How can a previous state be dependent on a later state? That doesn't make any goddamn sense either.

I was looking for a /qttddtot/ or equivalent so lemme post here before I make a thread.

/sci/ I'm a mathlet how would you guys go about calculating a best pricing plan between a recurring monthly fee with one time enrollment price and a more flexible pass system that can only be used an X amount of days?

Maybe I'm a wordlet too, if that doesn't make sense. So monthly fee is X + one time fee Y = PROFIT. How can I come up with a mathematic model for a one time fee that can be used for say 30 days like a punch card that would be equal to or greater than PROFIT?

AND considering capitalism you want to maximize profits so the punch out card should cost more than the regular monthly annual plan in order to encourage people to get the monthly plan but still offer flexibility and profit.

>>10506132
> Why does the fourier transform sometimes have a normalization factor and other times not?
It depends whether the parameter in the frequency-domain function is frequency (cycles per unit time) or angular frequency (radians per unit time).
If you define the transform using frequency as
F(ξ)=integral f(x)e^-2πixξ
then the inverse transform is
f(x)=integral F(ξ)e^2πixξ
However, if you use angular frequency:
F(ω)=integral f(x)e^-ixω dx
then the inverse is
f(x)=(1/2π) integral F(ξ)e^ixω dξ
This introduces an asymmetry between the forward and inverse transforms. This is often removed by splitting the 1/2π factor between the forward and inverse transforms to give
F(ω)=(1/√2π) integral f(x)e^-ixω dx
f(x)=(1/√2π) integral F(ξ)e^ixω dω
A similar issue arises for the DFT. With the most straightforward formulation (where the forward and inverse transforms differ only in the sign of the exponent), a "round trip" (application of the forward transform followed by the inverse transform to the result) scales the values by the number of samples, N. As it's subjective as to whether normalisation should be applied to the forward transform, to the inverse transform, or split between them, FFT libraries generally perform an unnormalised transform and leave it to the application to handle normalisation.

>>10504790
not exactly what you're looking after, but given a inner product vector space (say, continuous functions with the integral from 0 to 1 of the product as inner product) you can compute the BEST polynomial of degree "n" approximation to that function, using the idea that the best approximation of a point A on a line is the point B such that AB is orthogonal to the line.

You don't even need polynomials, any finite dimensional subspace of continuous functions for which you have a basis will suffice.

For more read section 6.C of Axler's Linear Algebra Done Right

is the average of 365 days worth of averagre the average of the year or no?

"26 children want to participate in a school play. How many ways are there to choose the children for the leading and supporting roles? If the lead and supporting roles both must have backups, then how many ways is there now to choose children?"

Oh my fuck I am doomed.

>>10507081
yes, if you count a year as exactly 365 days not taking into account leap years and leap seconds

>>10506904
please think about what you are trying to say, then write this post again. this is a complete mess

>>10507087
how many supporting roles are there? Are we assuming there are 26 roles, one being lead? Does each supporting role count as a different role, or are the rest just jumbled into "support"?

For example, if the setup is there's one lead and nine support roles to be filled, with who fills what being irrelevant in support.

Then you have 26 choices for leading role. Then you have to count 9 possible roles for the support roles. That would make it 26 + 25C9, where 25C9 is the binomial symbol (25, 9)

>>10507198
one lead and one support

>>10507216
Again, does it matter if one is lead and one support? For example, would you count the possibilities:
>Alice being lead and Bob being support
>Alice being support and Bob being lead
As one option or as two options? I'll assume two options because it's more natural

There are 26 possiblities to choose a lead, and 25 possibilities remaining to choose a support, so 26 x 25 for the first question. If they require backups, then you just extend this reasoning to get 26 x 25 x 24 x 23

humor me here because I know this is going to be retarded.

So the earth is a sphere. And we rest on the surface of this sphere. Is there a way to get from point A to point B on the surface of this sphere without actually traveling the physical distance between them? What Law would that break? What law prevents a thing from instantaneously being in point B from point A? There would be no difference in height from point A to point B so potential energy is preserved and since I wont be really moving, no energy is requred for momentum right? Help me be less of an idiot because I can't think of a reason we cant do this.

What am I doing wrong? I'm supposed to calculate the speed of the boat at the moment of the man beginning to move at 2km/h towards the beginning of the boat. I calculated the initial momentum as their combined mass times the speed of the boat, and equated it to the final momentum, which is a sum of the momentums of the boat and the man, separate. Where am I fucking up?

So [math] \forall \, x \in \mathbb{Z} \quad P(x) \\
x \, \in \mathbb{Z} \, \implies \, P(x)[\math] are not the same thing r-right?

So [math] \; \forall \, x \in \mathbb{Z} \quad P(x) \\
x \, \in \mathbb{Z} \, \implies \, P(x)[/math]
are not the same thing r-right?

>>10507483
why wouldnt they be the same thing?

>>10507483
why would they be the same thing?

>>10507592
>>10507593
I was thinking about the subset definition a-and I- they look to be equivalent to me but I am also a brainlet. Which is why I am here.

>>10507602
theyre the same

>>10507631
Yeah you're right I check the contraposition and it's negation and everything seemed to check out. I think.

>>10507320
What does the shape of the earth have to do with teleporting?

>>10505502
The hamiltonian should be an operator, a scalar operator.

>>10507710
because relative to the center of the thing that is pulling on you, you would be neither higher or lower

Not necessarily a stupid question but I'm a stupid person.

Earlier today I went to my neuropsychology appointment that I scheduled a couple of months ago. It was a series of brain test designed to look for symptoms of ADHD, schizoaffective disorder, etc. I definitely have a few shortcomings that should be discussed in a couple of weeks, but one examination stood out in particular (pic related).

I was given two sheets of paper, one after the other. The first one had the text RED GREEN and BLUE written in generic black text. The words were written several times in a random order. I was instructed to read them aloud from top-to-bottom, left-to-right. I did so like Sanic with no errors until she told me to stop.

The second piece of paper seemed to be the same principle, except there were no longer words, but a series of identical symbols [######], each colored red green and blue, in random and in dark ink shades. The order may have been the same as the first test. However, when instructed to read them aloud, my brain spazzed out. My chest felt weird and it felt like I lost my voice and could not follow the instructions. In the end we had to skip the test and I was not permitted to go back and try it again.

I wound up slightly pissed towards the end because both specialists essentially glossed over the happening like it wasn't a big deal, when it was by far the most interesting thing that happened in the whole four hours. Maybe it is protocol to not discuss complex possibilities on the same day as the examination but they could have just said that the happening will be acknowledged/under review.

Essentially the question is wtf just happened, and hopefully it will not be information they intend to disregard.

I remember my old science teacher told us it was not possible for the human body to drink 100% ethanol because the body treats it like a poison and would just vomit to expel it.

How true is this?

I've got a battery with 2 loads, one of which cannot lose power (although it doesn't use much). Whats the easiest way to turn off the other load, before it trips the battery controller and shuts down completely?

why live?

>>10508268
why not?

if being gay is genetic then how have they not died off since you can't have kids with the same sex?

>>10508269
because i rather sleep than wake up

>>10508272
>tfw genes can exist on both genders

>>10508301
if each gender has this gay gene, and they're not reproducing with the opposite sex since they're gay, then how is that gay gene propagating?

>>10508407
because a gene can become inactive or represent in effective breeding when put in the other gender

I'm trying to make a bot for some game. Say we have a 3x3 grid

B C E
D i H
G A F

with the cursor at i. it can only traverse the grid by swapping position with other cells. For instance, moving i up swaps place with C

B i E
D C H
G A F

and so on. So if I want to get A to (1, 1), I would do this

B C E B C E B C E
D i H -> D A H -> D A H
G A F G i F i G F

i C E C i E C A E
B A H -> B A H -> B i H
D G F D G F D G F

C A E i A E A i E
i B H -> C B H -> C B H
D G F D G F D G F

My question is: is it possible to alter the grid into

A B C
D E F
G H i

? If it is, what's the algorithm I can use. Also can someone point out what domain of mathematics this is?

>>10508476
https://en.wikipedia.org/wiki/15_puzzle

why does my mouth keep feeling dry and give off a poopy smell even after brushing my teeth and drinking a lot of water

>>10501042
Buy a lot of them, chance of success grows with more amount of lottery tickets.

>>10508272
>assuming
There's your problem right there, son.

>>10507920
After your tests are done, you should be able to talk to your psychiatrist about the results.
Knowing about the test before doing it can create false data, which is why proper tests are under lock.
Im sure the reason why they wont talk about it until the tests are all done is similar.

>>10507320
There have been observations in quantum physics where particles have spontaneously disappeared and reappeared in another location, traveling faster than the speed of light.
However, these particles are infinitesimally smaller than a human for example, and moving an object requires energy scaling up exponentially with the amount of mass of the object you're trying to move.

In Sci-fi, such as Star Trek, what they basically do is disassemble people down to the most basic of particles, and reassemble them somewhere else, thus "teleporting". However there is no guarantee that the person arriving is the actual same person that left, even if both individuals share the same memory etc. CGP Grey did a fantastic video about it on Youtube.

Im aware this post does not answer what physical laws are being broken and such, but to be fair laws are only valid until they're not. Having a deeper understanding of the universe /may/ invalidate all laws of physics as we know them today.

>>10507882
you're still moving to the side...

>>10508268
we're winning

https://www.tmz.com/2019/03/29/jussie-smollett-lawsuit-city-chicago-fired-empire/

>>10508715
Teleportation is not 'moving' per se, more like arriving at your point of destination without moving at all

>>10508721
I do realize however that all things are in constant motion, compared to all other things which of course also are in constant motion.
>TL;DR General relativity is fucked up

AM I FIGHTING WINDMILLS

>>10508476
It can be solved both by A* and BFS. It also might be solved using bitmasks which is much, much faster (think of the grid as bits, think what operations using bits you apply to shift onto the left, right, bottom).
I have gotten a solution for this in C++, might share if you're interested.

>>10508745
You still need to check whether the initial configuration is solvable or not. >>10508527

How to greentext ?

>>10508765
[green] [ /green] without the space before /

>>10508779
[math]\color{#789922}{\text {Thanks!}} [/math]

>>10508784
[math]\color{orange}{\text {No problem!}}\;\color{cyan}{\text{ I love color-posting!}}[/math]

[math]\color{red}{\text {(USER WAS BANNED FOR THIS POST)}}[/math]

>>10508745
Hmm is it possible to explain it to me instead. I did read up the use of A* in this sliding puzzle. Also using bitwise operation seems pretty cool. Didn't once occur to me to use that

>>10500887
test
>>>/sci/sqt

>>10508792
It is a search through a state space, how you model the state isn't really the point. What kind of explanation do you expect now? Read up on it, then ask specific questions if something is unclear and you need help.

>>10508790
[red] Oh noes! [/red]

>>10508820
[don't worry, everything will be fine]green[/don't worry, everything will be fine]

>>10508820
Loooool baaaiteeed, such a noob pleb lmaaaao xDDDD That's not how to do iiit [math]\color{red}{LMAAAAAAAoOOoO}[/math]

>>10508823
[modpost]>>10508823 Why are you poopy bums allowed out of your cages? It's over a day left till april >>10508825[/modpost]

>>10506981
Wow thank you so much. Really good explanation. Do you mind if I share it with my friends?

>>10504348
[eqn]c = \frac{\pi}{2} + a + b - \arcsin{\left(\frac{\sin{b}}{\sin{(a+b)}}\left(\cos{b} + \sqrt{\cos ^2{b} - \cos ^2{(a + b)}}\right)\right)}[/eqn]

>>10506758
My first guess that it's a single ring of very hot debris/gas/etc. orbiting the black hole (most of it on a decaying orbit slowly falling inwards). It looks so unusual because the gravitational lensing allows you to see the top & bottom of the ring on the opposite side.

Is a BS in Physics worth it? Why or why not?

>>10506758
That's called an accretion disk, which is present as long as the black hole is 'feeding' on nearby matter. You will also see beams of energy coming for the poles (non visible light) called jets. You can also look up quasars for more interesting pictures.

>>10502268
>>>/pol/

[math] - \frac{R}{a} \frac{q}{\sqrt{r^2+b^2-2 \ r \ b \ cos(\theta)}} \\ \Updownarrow \\
- \frac{q}{\frac{a}{R} \sqrt{r^2+b^2-2 \ r \ b \ cos(\theta)}}
[/math]

Can someone confirm that this step is allowed? I'm thinking:

[math] \frac{R}{a} = \frac{1}{\frac{a}{R}}[/math]

>>10509250
[math]\displaystyle \frac{R}{a} = \frac{R *\frac{1}{R}}{a * \frac{1}{R} }= \frac{1}{ \frac{a}{R} } [/math]

Do bootstrap samples always share the same distribution as the data set they are drawn from?

Ayo, /sci/, what are some software packages for brain dead simple but accurate water simulation?

>>10500887
How can I get started with doing mathematical regression with stochastic math?

>>10505936
jocker

why do people who an hero often do it in bath tubs (atleast in movies)?

>>10509694
I guess you mean filled bathtubs, right? Because warm water widens the arteries and prevents blood from coagulating.

How do I tell if I'm smart enough to major in computer science without going and getting a proper IQ test done?

>>10509801
Why don't you look into what the curriculum is and try a few introductory exercises yourself?
Unless you're just posting to bait some stereotypical CS replies.

Also, smartness is not the only variable you need to take into account. Do you have the discipline to do your work on time, whether or not you "feel like it"? Then that's probably enough. Good luck.

<math xmlns="http://www.w3.org/1998/Math/MathML">
<mstyle mathcolor="red">
<mtext>(USER WAS BANNED FOR THIS POST)</mtext>
</mstyle>
</math>

I'm trying to find x^4 (x-operator) using ladder operators, on a state n. Pic related is what I get, but it doesn't look anything like the correct answer. Did I do something wrong? Can my answer be simplified or something? I really don't understand this notation. I'm not even sure if my answer makes sense.

Why do black hole singularities experience time via entropy and hawking radiation but pre bb singularities do not?

>>10500887
Is reverse SAD a thing? I get hella depressed when the weather starts warming up.

>>10508532
bacteria. Try using mouth wash

>>10509801
Just enroll in CS classes and see how far you can get.

>>10504200
Metaphorical bump.

>>10509801
start by solving pic related

>>10510261
I know this is all in vain with respect to the original poster, because "proper IQ test" is a clear bait indicator. But in case anybody else is interested, I'll post this:
https://web.stanford.edu/class/cs106a/

I remember having seen your exercise in one of the archived versions of this.

>tfw stumped at second page of Rudin
Can someone explain 3) to me? Specifically why he subtracts p^2 -2 / p + 2 from p?

>>10510300
For these things, it is often beneficial to work backwards from the result you want.
Anyway, what are the requirements on q, and what do you know about p^2? This new expression (the difference you're asking about), needs to be a rational number, its square must lie on the same side of 2 as p^2, and be either larger or smaller than p, depending on whether p^2 is smaller or larger than 2.
Do a case analysis and see for yourself.

>>10510314
>This new expression (the difference you're asking about), needs to be a rational number, its square must lie on the same side of 2 as p^2, and be either larger or smaller than p, depending on whether p^2 is smaller or larger than 2.
Going full brainlet here but could you explain how the new expression satisfies each of those criteria? I know you asked me to do a case analysis, but I guess I want an explanation. How do you know that expression corresponds to a rational number? Also would I be correct in saying that the expression would be different if we were looking at the number 3 instead of 2?

can a chimera infant have 2 fathers and 1 mother?

>>10510322
> I want an explanation
doing the case analysis is the explanation. There's nothing more going on

> How do you know [that it is] a rational number
Well, it consists of sums and quotients of rational numbers. Can you escape the rationals doing this?

> Would [...] the expression be different if I [made it different]
Yes.. what did you expect?

The whole thing is just telling you that given a rational number r with r^2 less than 2 (for example), there always is a "next" rational number s that is larger than r, but such that r^2 will still be less than 2.

why not use hydrazine as a first stage fuel for a rocket? as far as I know it's mostly usually used for thrusters once in orbit

/mu/ here I am making a musical scale and need a list of numbers.
You dont need to know what a music scale is to answer my question.

What I want is the list of 11 numbers that fit all those rules:
1-Each number is more than 1 and less than 2.
2-Each number is X/Y
3-I want the list with the smallest biggest of X or Y value, as some example at an list of 2 numbers with the numbers 3/2 and 4/3, the smallest biggest value or X or Y is 4.
4-Rule 3 must also take into account the result of (X/Y)/(another X/Y) where the first X/Y of this formula is the bigger one. So at the list of two numbers with the numbers 3/2 and 4/3, you must take into account (3/2)/(4/3) that is 9/8, so the smallest biggest number of this list of numbers is not 4, but its actually 9

>>10510343
Ok thanks, how does this show that "the rational number system has certain gaps" as the author goes on to say?

NaOH + H2O just results in free Na and OH ions in solution + released heat energy. What happens if you let the water evaporate? If you get NaOH back, where does the energy to reform it come from?

>>10500887
What's the square root of an octagon?

https://youtu.be/blM3fsGTc-8

How the fuck do I understand these proofs in set theory? Is there like a "how to understand proofs for complete brainlets" I can read?

Ok guys so people say bachelors is a 4 year degree, and associates is a 2 year degree, does that mean if I start from the beginning of college for my bachelors it will actually take 6 years, 2 for associate, and 4 for bachelors, or will it actually be 4 years, 2 in associate, and then 2 in bachelors?

>>10510497
both, depending on what you study and your caseload. The majors would have to compliment each other.

>>10500887
https://en.wikipedia.org/wiki/Wave_function_collapse
> ... appears to reduce to a single eigenstate due to interaction with the external world; this is called an "observation".

How do something/someone cause this interraction which causes a wave function collapse? Is this what quantum computers do? How do they do it?

>>10510876
Since im not going to be a full time student the whole time, it might take me longer, it was mainly the bachelors degree I was curious about, since im paying for my own college, I just wanted to get rough cost on tuition for a uni.

>>10500887
Any clue?

>>10511247
Have you tried using an integrating factor?

Say I have a wheel spinning with air in it at constant speed. after a while the friction will cause the air inside to spin with the tyre as well. my question is after the system stabilises how will the air density vary with the radius. I think I have the solution but I need to verify it

>>10511392
Yeah but i get stuck when trying to impose the initial condition onto an integral

>>10511817
You're talking about an air-filled tire spinning in a system without gravity on it, yes?
Post your solution then, and anon will verify it

>>10511831
So show your work so far. I get [math] y(t)
\tan t = \int { g(t) \over \cos t } \text{d}t[/math]

>>10511817
>>10511844
The function which is the solution will satisfy the integral. I skipped over some trivial stuff

>>10510353
literally read the first paragraph of your own picture

>>10509943
Bump? I found this problem that's kinda similar, but I still don't really understand how to do it.

>>10511247
y'+tan(t)(y)=g(t)sec(t)
and then I think you start by treating as a first order homogeneous, then you do something else after that don't remember.

>>10511831
>initial condition onto an integral
what? I thought the initial condition just determines your specific solution on the family of curves which would be solving for c.

Would someone kindly help me with some notation? It's been years since I have been in a mathematics course. What do you suppose this means:
[eqn]
sun \leftrightarrow view \, azimuth \; \omega \in \left \langle 0; \pi \right \rangle
[/eqn]

where [math] sun [/math] and [math] view [/math] are "directions" according to the paper. I'm not sure what the double arrow is saying, other than maybe the angle from one to the other. Is this how you would interpret it?
Additionally, what exactly do they mean by azimuth here? What would an azumuth angle between two vectors be? Is this the angle of the projections on the xy plane?

where can I find information about the estimated future of space colonization? I want to learn about the basis that colonies are predicted to be founded upon, like a nation would have its own colony, but then there would be colonies based on religious belief, political belief, by ethnicity, ethical belief (transhumanism etc) and others.

Linear Algebra teacher introduced Vectors and Covectors through Einstein notation, which I can't understand (because the sadist decided to simultaneously introduce it at the same time). Is there any decent introduction that uses matrixes instead?

>>10510349
doesn't the western chromatic scale already meet all of these criteria if you approximate the ratios with respect to C to a fraction? See:
https://en.wikipedia.org/wiki/Equal_temperament#Comparison_with_Just_Intonation
https://en.wikipedia.org/wiki/Chromatic_scale#Other_tunings

If a Farnsworth Fusor gets up to 45 million K with relative ease, doesn't that mean that by Wien's Law that the peak wavelength emitted by the blackbody radiation would be in the range of 67E-12 m, or 67pm? AFAIK that's nasty fucking gamma.

>>10512739
I'd say the \leftrightarrow signifies the point of the observer, from which the vector towards sun and view originate. Azimuth is the name for the horizontal part of a direction in spherical coordinates.

Using plastic bottles really contaminates you? People at my uni keep telling me that about my water plastic bottle and that i should boy a metallic one

>>10513735
Depends on the plastic, but in general yes. Whether it's in any way significant is another issue. An aluminium water bottle will typically have a plastic lining anyhow, so you can laugh at them for that. Personally, I wouldn't worry about PE, PP, PTFE, probably not about PS, but from all the "pthalate free" I see on tupperware I'd personally do research into whether PET is safe. I think it's fairly widely accepted that BPA leechant has minor hormonal effects, so steer clear of it for food purposes, but I doubt you'd find any of that in a developed country. PET on the other hand is commonly used for soda bottles. Personally I just use a glass sparkling water bottle since glass has the least impact on flavour. Not terribly good for a bicycle drink bottle holder though.

>>10500887
can ice cut?

>>10513828
If you help it out a bit, you can forge a knife.

Why do we have math and engineering threads daily, but not physics threads?

>>10514098
Because you don't create them.

combinatorics is blowing my head up, you have to play a series of 5 notes in the correct order, each note has 3 distinct tones to it, how many permutations are there?

>>10514168
3^5?

>>10514171
that's for r sequences of n many distinct elements, but I don't know if that's the case either.

>>10514177
Why wouldn't it be? 3 tones for the first note * 3 tones for the second note * etc.

>>10514168
How many notes are in the series?

Given an event with a duration that has a probability of occurring at a regular interval, how would one determine the "uptime" or average percentage of time in which the event is occurring? It's the overlapping of such events that stymies me.

>>10514239
Sounds like you could benefit from some convolution.

>>10505951
it's about the mass of an object and it's magnetic field generated. A heavy dense object can bend space around it but space is necessarily an object the crumpled or folds it can tear, it's a bunch of dark matter that's almost hollow like it nature but still in essence pertains substance. A heavy dense object warps this and an object with momentum coming towards this is pushed away dependent on each object or planets magnetic field it produces in proportion to it's density and composition. This ultimately creates synergy in a way. Our earth has a magnetic field that pulls it in towards an object like the sun which is dense enough to impact space around it creating a bend like nature. Imagine space is a composition of dark matter we call x, x has C infinity amount of layers or compromises all of which contain billions of dark matter we can x, around the sun alone there is x1, x2, x3 and so on. the Sun pulls down on this layer of dark matter creating a warp effect which bends space as to create a funnel like effect. Grab a heavy magnet with a thin layer of metal around it and a wide cone like or funnel shape object, now grab a smaller magnet and repeat and spin it around the larger magnet.
Gravity is just magnetic force generated by the inner cores of each planet. when you are in open space floating you are at the furthest point away from magnetic force hencr anti-gravitational.

>>10514247
The only convolution I am familiar with is of laplace transforms. The most combinatorics I've gotten is statistical physics. I don't know what I'm doing here. It feels like the kind of thing that should reduce to some simple coefficient of the three variables accounting for the average overlap. I should think on that, I guess.

>>10514258
all of this occurs in the middle of the expansion and eventual heat death of the universe. Easy explanation to this is as such, imagine that for an accelerated particle it requires energy right and it will continue to travel as fast it can dependent on that energy it has to travel that either gathering or losing more energy depending on how the particle becomes impacted, density etc... if it forms or collects more energy it can stagnate and begin to move slower etc... but ultimately it will come to a point where it either consumes itself or gets consumed. Now eventually this light must continue and will continue until it reachs a point where all the dense objects in the universe eat each other and form one object of density that matches the amount of anti-matter or rather dark-matter in which it behinds to completely drag this matter or bend and warp it (think of a trampoline) after this it can tear the dark matter, which I should add has no kinetic energy but rather forms the essence of bonding around us, all dark matter is bonded, when this year cause enough energy to bond back that it forces the dense object to propel and expand the dark matter exploding outward ad infinium

>>10514239
>>10514247
>>10514261
I just realized the scenario I am abstracting has an extra complication in that the interval has a different value while the event is occurring. So, fuck finding a closed form solution. This goes to simulation.

How do I even solve these two differential equations using the Runge-Kutta method? Assuming I would use MATLAB/Octave.

When i work out the velocity of a charged particle in an uniform electric field i find that the velocity is opposite to the electric field itself. This is obviously wrong but i cant figure out why. The negative arises when i integrate z/(a^2+z^2)^(3/2)

>>10514627
what charge is the particle

If I clone Albert Einstein then will he have the same exact brain structure as the original, meaning that weird mutation in his brain which allowed him to be such a wizard?

And if we go by this theory then can I technically revive my ancestors by cloning them? will they have the same personalities and diseases, minus the attitude and mentality?

>>10514648
A large part of the process of developing a brain is determined by the environment. Maybe look up "Myelin sheath", just as an example. So, if you can't reproduce the environment exactly, you won't end up with an exact duplicate of the person.

Is it true that [math]\mathbb Q\times \mathbb Q\cong \mathbb Q[x]/(x^2-ax)[/math] where [math]a\in\mathbb Q \backslash \{0\}[/math]?

>>10514194
5, as I said.

>>10514783
Not if a is negative. Then we can take a=-4, and (x+2) divides zero.
Huge hassle of a polynomial to make an isomorphism in the a>0 case, and I can't come up with any other problems.

>>10514905
five elements with three variants each means 5^3 possibilities. If you want to get more used to it, write it down explicitly for a smaller number; for example (with _H_igh, _M_edium and _L_ow notes) all 125 possible sequences of three notes are:
LLL
LLM
LLH
...
LHH
MLL
MLM
MLH
...
HHL
HHM
HHH

>>10514916
>x+2 squared is x^2-ax
Sorry, my retardation gets the better of me pretty often.
Anyhow, every zero divisor in QxQ is of the form (a, 0) or (0, a).The expression on the right has two of them, x and x-a, and the rest are necessarily multiples.
This means that you just need to track down the ratios of what to send to what.

>>10514936
Yeah thanks, had a lapse of mind

>>10500887
Reminder that dumbass christcucks don't believe in dinosaurs despite ample evidence pointing to their existence<div class="like-perk-cnt"><img alt="" width="451" height="75" src="//s.4cdn.org/image/temp/dinosaur.gif"></div>

>>10500887
Why dont we use cancer cell as a cultured meat? They are more easy to grow and i suppose the taste is not very different from real meat. Also, we dont get cancer from eating cancer, thus its pretty safe.

>>10515715
Because culturing cancer cells isn't exactly easy. Also "cells" aren't meat, to get meat we need something to grow muscle, or at least something with similar composition. You'd basically be eating cultured offal.

>>10515729
Oh. Thats helpful. Thanks

Anyone know of any alternatives to textsheet or litanswers? I cant pay 15 bucks a month to the Chegg jews, and I like to cross check my homework answers.

>>10515806
What subject? Might be worth buying a textbook with plenty of questions.

Can an EE major explain this to me? I figured if the frequency changes, the impedences change, so you have a new Zth/Vth, and a different equivalent circuit

>>10515812
Statistics, Using the textbook Probability and Statistics by Rosenthal

>>10515817
I guess it depends on if impedances are given as "5jΩ" or "0.1F" in the referred context. I'd venture to say that the former is more common if you're being taught about those equivalent circuits and phasors before being taught about fourier transforms, matching networks, and filters, as I was. If the question is asking about the concept of those equivalents, then obviously they're concepts that don't solely apply to a particular frequency, but that would be a badly worded and obtuse question, since it's referring to the "____ equivalent circuit", which in my eyes does refer to a single instance of that circuit. Not an EE though.

>>10515818
Have you tried R or iNZightVIT? The latter being a UI layer built atop R that seems to be pretty intuitive and quick to use, as software to analyse data sets. Both being developed at my university. It's hardly giving you answers, but it is providing a framework to better understand data.

Does /sci/ Euclidea?

>Given two rays forming some angle and a point inside that angle, find a circle which is tangent to both rays and passes through the point, using only a compass and straightedge.

Best I can do is 13 moves, the goal is 11. (Each line and circle drawn is one move)