/sci/ - Science & Math

that picture lol

is that pic fo real?

>>6719107
yes

>>6719108
https://www.youtube.com/watch?v=OPV3D7f3bHY

>>6719102
I want my descendants to have weak upper body but strong legs. If me and my descendants of 50 generations do squats and not upper-body, what will the effects be on the bones of my future generation?

If I have a ten foot object how far away do I need to be for it to be 10 degrees on the horizon?

>>6719102
Can I use the scientific method to find the perfect girlfriend?

>>6719114
>you would lose

BASED
A
S
E
D

>>6719280
>I want my descendants to have weak upper body but strong legs. If me and my descendants of 50 generations do squats and not upper-body, what will the effects be on the bones of my future generation?

Not really. The best way to achieve this is to create or find an environment where strong legs are adaptive and strong upper bodies are not, and then having your line exclusively mate with people from this environment.

>>6719114
>Pioneering physicist
>2014

Where do babies come from /sci/?

>>6719389
Mothers who think everything is an insult.

Is psychology an art or a science?

how do i work this out? i really dont understand how the head of the vector alters the answer

>>6719415

1) b+? = a -> ? = a-b

2) a+? = b -> ? = b-a

3) b+a = ? -> ? = a+b

>>6719415
i'm no expert, but if i remember correctly 1) -b+a; 2) -a+b and 3) b+a

>>6719399
It's at the intersection between social science and natural science. Either way, it relies on the scientific method and is a science.

>>6719415
A vector is a length and a direction. If you travel down a vector 'a' followed by a vector 'b', your path is the vector 'a' + 'b'. If you go down a vector backwards, that's the same as the negative of the vector.

>>6719421
>>6719420
how are you guys getting these answers?

>>6719430
Take the unknown vector and imagine, you have to get from the simple end of it, to the end with the arrow, but you can move only using other vectors, that are not unknown. Then you sum all the vectors, that you traveled along. If you move from the arrow end, to other end of a vector, that vector becomes negative.
In 1st case, to get to the arrow end of ? vector, you have to move along vector b first, and then along vector a. But you move from arrow end to other end while moving along vector b, therefore, b becomes negative and the sum is -b+a. Directions are important when talking about vectors, so i think you can't use comutative property (switch them around so -b+a becomes a-b)

>>6719432
ah! great explanation mate! thanks a bunch

Person A, B, and C are all strangers.

>Person A and Person B ask Person C what the probability is that A and B share a birthday
C says 1/365^2.

>C asks A what the probability is that A and B share a birthday
A says 1/365.

Are they both right? With C's knowledge, there are 365 possibilities for each of A and B. But A knows his own birthday and so there is only 365 possibilities for B.
Ignore leap years, of course.

>>6719432

I'm going to do up an example with coordinates on it to illustrate, BRB.

How do they measure quantum particles in the double slit experiment?
Like how do the devices work?

Will I ever use the math that is being thought in EE or is it there just to waste my time?

>>6719494
No.
It doesn't matter if you know the birthday of one person, because they could both have birthday on each day of the year.
If you set a day and say "What is the probability of A and B both having birthday on the 4. of June?" it would be 1/365^2.
Since you didn't define a date, there are 365 outcomes for both having the same birthday ("What is the probability of A and B having birthday on the 1. January, 2. January....OR 31. December?") so you divide 1/365^2 by 1/365, which is 1/365
The probability that 2 persons share a birthday is 1/365
The probability that 3 persons share a birthday is 1/365^2
The probability that 4 persons share a birthday is 1/365^3
etc.

>>6719500

Muh Teaching Credentials

>>6719511

Depends on what you're being taught and what you're going to do later but as a general thing: There is no useless math in Engineering. The things they teach you, they teach because SOME aspect of EE uses it.

What are you going through?

I'm good in mathematics but I want shekels. What is the highest payed field I can study, that comes close to math?
>inb4 math major 300k starting

>>6719511
You need Fourier transforms and all the other shit to properly do signal processing, for starters. The parts that seem removed from reality and theoretical are required in order to understand the parts that aren't. None of it is useless.

>>6719523
Actuary
Financial analyst
Mathematician
Nuclear engineer
Aerospace engineer

All math-intensive careers that can easily net you six figures

EE or CS? With which can you get the more fun jobs later? Which is more flexible?

If light slows down in a dielectric medium, does it impart momentum to it via conservation of momentum?

>>6719114
Seems scripted

>>6719582
Most everything with Stephen Hawking is scripted.
It takes him a while to select the words on his computer so they're all pre-selected.

>>6719102
I just registered myself in the classes for next semester I have
Discrete Math
Calculus 1
Statistics
Scientific programming in C
Macroeconomic theory 1

How many hours of work should I give each course? How fucked am I?

>>6719584
But who wrote the script?

>>6719587
God did.

>>6719589
You mean the AI?

>>6719589
Lol
>>6719587
Probably somebody close to him and his research that discusses the script with him needing nothing but Yes or No questions

>>6719586

none of these are hard. Just study, there is no secret to academic success except for dedication

What is good book to learn multivariable/vector calc with more rigour?

I've heard of marsden's vector calculus, apostol's calculus vol 2, spivak's calculus on manifolds, edwards' advanced calculus of several variables and munkres' analysis on manifolds...

But I have no idea which one to pick, or if any of these at all.

>>6719280
No, that's not how evolution works. There would have to be a mutation that allows your leg muscles to be stronger or more developed for future generations to have stronger legs. What you do in your lifetime has no effect on your offspring.

>>6719606
What about epigenetics?

>>6719611
It's just like MS' favorite excuse - that's not a bug, it's a feeture.

Is math a science? Is economics a science?

>>6719631

>Is math a science?

No.

>Is economics a science?

lol'd no

>>6719668
Why?

>>6719677
>Is a dolphin a flower?
>No
>Why?

Well at least you're sure fitting into the theme of the thread.

>>6719684

I bet you think physics is a science you shitter

Lets say I have an event A of probability 0.77, and an event B of probability 0.23

I don't know which event is going on, but I have a probability of 0.8 of being right while guessing it

And lets say I made a guess that the event going on is the B event.

What is the probability that I was right?

>>6719726
>I have a probability of 0.8 of being right
>What is the probability that I was right?
Uh. One of us is missing something here.

>>6719728
Let me rephrase that
Event A has a probability of 0.77
Event B has a probability of 0.23
A random event between those two starts going on right now.
I can't certainly tell what event is going on right now, but I have a probability of 0.8 of making the right guess

If I made a guess and said 'The current event going on is B', whats the probability of it actually being B?

Why isn't Psychology recognised as a science by many of you?

>oh boy here we go

>>6719631
> math
a formal science
> economics
social science

http://en.wikipedia.org/wiki/Science

>>6719734
And it is not as simple as multiplying the % of B happening (0.23) with the % of me being right (0.8)

0.23 * 0.8 = 0.184
Actual answer: 0.5443

If I throw an object straight up in the air (vertical direction), will it take more time for it to go up or to come down? I know that the time is the same if it's done in vacuum but I'm a bit confused otherwise...

>>6719800
I think the time spent going up and going down is identical. I'm not sure though.

If I have a question relating education, should I ask it on /sci/ or /adv/?

Thanks in advance!

>>6719800
Depends on the shape of the object, how you throw it, and other things that affect air resistance. Generally though, it will take the same time both ways.

>>6719800
depends how fast its initial speed is, if its faster than terminal velocity then it will take more time to come down, if its under terminal velocity then it will be the same, assuming no wind and the density of air to be constant (ie the object wont go very high for air density to change noticeably)

>>6719777
>>6719734
anyone?

>>6719734
>Event B has a probability of 0.23
>whats the probability of it actually being B?

>>6719910
Thank you bro, this is the answer I was looking for.

Cancelling for noobs:

x/63 = 27/x

I learned that I can now cancel 63 and 27 by dividing by the greatest common factor (7):

x/9 = 4/x

But if I do this with x, the equation goes

1/9 = 4

What is my mistake?

>>6720000
27 / 7 =/= 4.

>>6720000
>the greatest common factor of 63 and 27 is 7
WAT

>>6720000
27=3^3
63=3^2*7

>>6720000
you cancel weird
x/63=27/x
(x/63)*63=(27/x)*63
x=27*63/x
x*x=27*63/x*x
x^2 = 3^3*3^2*7
x= notanicenumber

>>6720006
>>6720013
>>6720017
>>6720020

Sorry, my bad, 28 instead of 27. But my problem was related to the xes. Can I cancel them?

>>6720058
no.
x/a=b/x
x/a*x = b/x*x
x/a*x = b/1
x*x/a = b

What should I expect for precalc and calc1 courses in college given I'm not too great at math iin general? As I'm aware, it uses trig and algebra heavily - what should I brush up on specifically to keep ahead of the curve? I was told to get my trigonometric identities down but I'd like to know what else.

(I know this board isn't for uni help but then again this is a misc. Questions thread)

>>6720077
http://4chan-science.wikia.com/wiki/Mathematics

Use Khan first to refresh what you need to know, then read Stewart's Precalculus.

If light doesn't have mass then why does it have a very small push?

>>6720110
Because it doesn't have a small push, retard.

>>6720114
No, light has momentum and applies pressure. Turns out energy and mass are the related things.
For light, Energy = |momentum|*c
In general E^2 = |momentum|^2*c^2 + mass^2*c^4.

>>6720110
Light does have mass, it's just very insignificant. I can't remember the aritcle's name but I recall reading somewhere that a large enough object to catch sunlight weighs more when it's under the Sun's rays than when it is not. It's a small change but it did prove that light had an effect.

>>6719389
How do I maek babby??

Has anyone really decided as to even go that far in wanting to do to look more like so?

>>6720166
No it doesn't.

I guess that the object would appear to weigh more due to radiation pressure

>>6720194
Is light not made up of photons? Do photons not have mass? Forgive me if I seem like an uneducated nonce but I was under the impression that light and photons were the same thing?

>>6720197
Light can be described both as particles and as a wave. That is one of the principles of quantum mechanics.

To answer your question, photons have no mass

>>6719945
Event B has a probability of happening of 0.23
But I have a probability of 0.8 of making the right guess

If I guessed it was B, whats the probabilty of it actually being B, and not me being mistaken?

The answer is 0.54something, but I don't know why.

>>6720206
Well i F=m*a and photons have no mass, how can they apply any force to solar sails for example.

Does someone know the function of an angle of a pendulum without using the small angle approximation? I've only found the period.

>>6720689
There's other kinds of force
lets say, radioactive pressure

or the recently discovered, microwave vacuum pressure (this one allows to create small thrusts without any force in the opposite direction)

Even you can see it, magnets and magnetic shit can apply a force regardless of matter

>>6720450
>The answer is 0.54something, but I don't know why.

You, my nigger, need to get acquainted with "Bayes Theorem" and also "Base Rates."

An answer that illustrates base rates:

You can pick A or B
You have a 0.8 chance of picking correct.

Before you pick anything, we learn that A happens 100% of the time and B happens 0% of the time.

You pick B, what is the chance that you are right? Well 0% of course, because B never happens - your .8 chance of being right is irrelevant to this - or perhaps better understood as a .8 chance of (picking the correct answer), rather than a .8 chance of (the answer you picked being correct.)

Now, base rates of 100% and 0% don't actually exist (You need infinite bits of evidence to show that something is happens at 100%) so it's never this easy.

Let's take a different example: There is a jar with colored balls (There is always a jar with colored balls in these examples) and within it are 90 dark blue balls and 10 black balls.

A ball is drawn and shown to you very briefly, then replaced in the jar. Because the colors are close to similar and you're only seeing them briefly, you cannot tell the difference between them with complete certainty - rather, if you see a ball, you have a .7 chance of identifying the correct color before it is put back into the jar, otherwise you guess the wrong color.

Now you are shown a ball. You call out "Dark blue." What is the chance that you're right? Fairly high - most of the balls are dark blue, and you're pretty good at identifying balls. But in numbers?

(Continued)

>>6720977

There are four scenarios:

The ball is blue and you call blue
The ball is black and you call blue
The ball is blue and you call black
The ball is black and you call black

And for sake of easy math, let's call the sample space 10000.

In 9000 the ball is blue and you make
- 6300 true guesses
- 2700 false guesses (That would be the 70/30 split from above)

In 1000 the ball is black and you make
- 700 true guesses
- 300 false guesses (Still 70/30)

So, dividing that out over our four scenarios:

The ball is blue and you call blue - 6300/10000
The ball is black and you call blue - 300/10000
The ball is blue and you call black - 2700/10000
The ball is black and you call black - 700/10000

Our example from before: You called Dark blue. What is the chance that you are right. Well, there are 6300+300 tests where you call blue, and 6300 tests where you call blue and are right, so the chances of you being right are 6300/6600 = .95454...

Which makes intuitive sense too - if you ALWAYS call "dark blue," you'll be right 90% of the time (because 90% of the balls are dark blue), and then you increase the chance of being right by looking at the ball and being better than 50/50 at spotting the color.

>>6720110
Sigh. copy-paste lesson time.

The full equation is
<span class="math">E^2=(mc^2)^2+(pc)^2[/spoiler]
where p is momentum

Mass at rest doesn't have momentum:
<span class="math">E^2=(mc^2)^2+(0 \cdot c)^2[/spoiler]
<span class="math">E^2=(mc^2)^2[/spoiler]
<span class="math">E=mc^2[/spoiler]

Light doesn't have mass, but has momentum:
<span class="math">E^2=(0 \cdot c^2)^2+(pc)^2[/spoiler]
<span class="math">E^2=(pc)^2[/spoiler]
<span class="math">E=pc[/spoiler]

Photon's momentum p is
<span class="math">\displaystyle p=\frac{h}{\lambda}[/spoiler]
so its energy is
<span class="math">\displaystyle E=pc=\frac{h \cdot c}{\lambda}[/spoiler]

A photon's equivalent mass is calculated by determining
its energy, then inserting that value into
<span class="math">\displaystyle E=mc^2 \Rightarrow m=\frac{E}{c^2}[/spoiler]

By using h and wavelength directly you get
<span class="math">\displaystyle m=\frac{h}{\lambda \cdot c}[/spoiler]

SO - how is this relevant?

Well, sometimes you make very precise guesses about exceedingly unlikely events, and you will get bad results if your policy is "The test is very precise, so we will act as if it is also correct."

Let us say that I am a medical practitioner examining women for breast cancer. I am highly skilled, which in this case means that given any case before me, I will predict the correct answer 90% of the time and the wrong answer only 10% of the time.

But breast cancer is not so very common - among all the people who come in to get screened for it, only 1% actually has it.

Now I tell you that you (Or your daughter, if male) have breast cancer. Do you? Should I schedule you for a masectomy right now and disfigure you, or should we maybe run a different test, get a second opinion?

Pic related.

Is Cambridge better than Oxford?

>>6720986
I'm guessing you want the probability of a wrong positive test
That's as simple as P(pos test) = P(pos test | neg)P(neg test) + P(pos test | pos)P(pos test) = 0.01 * 0.9 + 0.99 * 0.09 = 0.0981

>>6720998
probability of a positive test*

>>6720992
Depends on what tou want to study. You want to be an engineering then Cambridge. You want to be James Bond(or business man, or whatever) then Oxford

>>6719107
>lol
Clearly a newfag

>>6720986
http://opinionator.blogs.nytimes.com/2010/04/25/chances-are/

>>6720986
http://en.wikipedia.org/wiki/Conditional_probability#Common_fallacies

>>6721082

Nah, fuck signing up for some site. Do they say anything interesting?

Am i on the internets?

>>6719114
that was very horrible

>>6721132
https://support.google.com/chrome/answer/95464?hl=en

>>6719110
top kek
thank you based professor hawking

how do i differentiate 3/y = arcsin x using implicit differentiation? i cant figure out how to do the 3/y part

i tried using the y = arcsin x <=> y' = 1/sqrt(1-sin^2x) thing but it doesnt work when theres a fraction with y in it, wat do? am i dumb or what

>>6719738
It used to be a pseudo-science not that long ago. Old sentiments. Freud and Roshard were philosophers/lunatics. I don't recall who introduced scientific method into psychology, but it's quite recent.

>>6719734
|
| - 0.23 is B
| |-0.8 is right
| 0.2 is wrong
|
0.77 is A
|-0.8 is right
0.2 is wrong

calculate the rest for yourself

Is >videoreleated related to fap only? Listening to music which I enjoy leads to the same dumb-mode, as if I fapped 3 times in a row.
https://www.youtube.com/watch?v=wSF82AwSDiU

If I don't like the way <span class="math">\mathrm{sgn}(v(t))[/spoiler] looks, could I write it <span class="math">\mathrm{sgn}[v(t)][/spoiler] and still have it be correct notation?

>>6721291
Yes.

>>6721219
>don't recall who introduced scientific method into psychology, but it's quite recent.

that happened with the behaviorists. their philosophy of science was strongly influenced by logical positivism (all meaningful truths are either analytic or empirically verifiable).

behaviorism was eclipsed by cognitive psychology by the 70's and logical positivism pretty much died out by that time too for other reasons

>>6721071
People use lol here sometimes, fucking newfag

>>6721433
so it was Skinner. Thanks anon, maybe I remember this time.

>>6721071
>>6721439
newfags gonna newfag

>>6721213
4 hours later im still stuck on this :[

>>6719513
What's the probability that in a group of x people at least 2 share the birthday?

>>6721524
(1/365.25) ^ X

>>6721533
Maybe i expressed myself wrong.
as x grows so should the probability, approacing 1 as x->infinity.
if i remember correctly if something has a 1% chance of happening, doing the thing 100 times gives a 60 something %

>>6721533
it's wrong, it goes towards 0 when x approaching infinity.

>>6721524
For n people, the probability of 2 having one birthday is
<span class="math"> p(n) = 1 - \frac{365!}{365^n(365-n)!} [/spoiler]

This doesn't include the 29. February though. So if n=366 the chance of 2 persons having the same birthday is 100%

>>6721524

Possible combinations:

b-people having birthday on <span class="math">d[/spoiler] day of the year
n-people having birthday on any other day

x = 2: bb nn
x = 3: bbb bbn nnn
x = 4: bbbb bbbn bbnn nnnn

Probabilities (assumed that year have 366 days each 4 years, which is not true btw):

A-at lest 2 people share a birth date

<span class="math">P(A) = 4/1461 P(A') = 1457/1461[/spoiler]
<span class="math">P(A) = (4/1461)^{2} + (4/1461)*(1457/1461) P(A') = (1457/1461)^{2}[/spoiler]
<span class="math">P(A) = (4/1461)^{3} + (4/1461)^{2}*(1457/1461) + (4/1461)*(1457/1461)^{2} P(A') = (1457/1461)^{3}[/spoiler]

Patterns & Conclusions:

So calculating the <span class="math">P(A)[/spoiler] is a little bit complicated but we can easily calculate <span class="math">P(A')[/spoiler] and <span class="math">P(A) = 1 - P(A')[/spoiler]. Since we notice <span class="math">P(A') = (1457/1461)^{x}[/spoiler] then <span class="math">P(A) = 1 - (1457/1461)^{x}[/spoiler].

You're welcome.

>>6721592
It can't be true though.
If x=366 (367 if including 29.Feb) the probability has to be 100%.

Confused econ fag here
Can anyone tell me What part of calculus is this?

Z = f(x, y) = x square * sqrt of e square y + y * sqrt of e square x

I don't know if my pic will upload because im on my phone and the solution is not so important to me, i just want to know what is it part of because i skipped my classes

So combination and permutations always get me confused.

In a sample of 2000 people where 120 win the contest, how many different combinations can there be? Isn't it simply 2000P120?

>>6721608
yeah, I noticed that. but how do you get rid of this? There need to be f(n) incorporated somewhere here, where f(n=2) > 0 and f(n>365) = 0. Any ideas?

What is the best way to kill yourself? I'm not planning to but I heard that some people have survived being shot in the head and if you shot yourself the wrong way you could stay alive and paralized or some shit. So, what is the most effective while at the same time the most painless way to kill yourself?

>>6721622
Firstly, define <span class="math">\mathcal{S}[/spoiler] to be a set of N people and let <span class="math">\mathcal{B}[/spoiler] be the set of dates in a year.

Define the birthday function <span class="math">b:\mathcal{S} \mapsto \mathcal{B}[/spoiler] to be the map that sends a person to their birthdate. So everyone in <span class="math">\mathcal{S}[/spoiler] has a unique birthday if and only if the birthday function is injective.

Now we consider how many functions, and how many injective functions, exist between <span class="math">\mathcal{S}[/spoiler] and <span class="math">\mathcal{B}[/spoiler].

Since <span class="math">|\mathcal{S}| = N[/spoiler] and <span class="math">|\mathcal{B}|=365[/spoiler], it follows that there are <span class="math">365^N<span class="math"> possible functions, and \dfrac{365!}{(365-N)!} possible injective functions).

Let A be the statement "Everybody in the set \mathcal{S} has a unique birthday" (so P(A') is what we are actually looking for). By definition, P(A) is the fraction of injective functions out of all possible functions (i.e., the probability of the birthday function being one that assigns only one person to each birthdate),
which gives P(A) = \dfrac{365!}{365^N(365-N)!}.

Hence, P(A') = 1 -\dfrac{365!}{365^N(365-N)!}

Source: https://en.wikipedia.org/wiki/Birthday_problem[/spoiler][/spoiler]

>>6721641
Most likely, a shot to the head from under your chin or through the roof of your mouth etc, will kill you. Though, if you want to be 100% sure, you could jump down a bridge with a pianowire loop around your neck, or simply bleed out by cutting one of your main arteries if you have the balls.

captcha: dbynne Hemorrhage (lel)

>>6721622
There is a chance that latex will fuck up my post again. If that is the case just use the source link: https://en.wikipedia.org/wiki/Birthday_problem


Firstly, define <span class="math">\mathcal{S}[/spoiler] to be a set of N people and let <span class="math">\mathcal{B}[/spoiler] be the set of dates in a year.

Define the birthday function <span class="math">b:\mathcal{S} \mapsto \mathcal{B}[/spoiler] to be the map that sends a person to their birthdate. So everyone in <span class="math">\mathcal{S}[/spoiler] has a unique birthday if and only if the birthday function is injective.

Now we consider how many functions, and how many injective functions, exist between <span class="math">\mathcal{S}[/spoiler] and <span class="math">\mathcal{B}[/spoiler].

Since <span class="math">|\mathcal{S}| = N[/spoiler] and <span class="math">|\mathcal{B}|=365[/spoiler], it follows that there are <span class="math">365^N possible functions, and <span class="math">\dfrac{365!}{(365-N)!}[/spoiler] possible injective functions.

Let A be the statement "Everybody in the set <span class="math">\mathcal{S}[/spoiler] has a unique birthday" (so P(A') is what we are actually looking for). By definition, P(A) is the fraction of injective functions out of all possible functions (i.e., the probability of the birthday function being one that assigns only one person to each birthdate),
which gives <div class="math">P(A) = \dfrac{365!}{365^N(365-N)!}</div>.

Hence, <div class="math">P(A') = 1 -\dfrac{365!}{365^N(365-N)!}</div>[/spoiler]

>>6721656
I guess the most painless option would be shooting yourself? But it's not as effective as the others?

>>6721622
Firstly, define <span class="math">\mathcal{S}[/spoiler] to be a set of N people and let <span class="math">\mathcal{B}[/spoiler] be the set of dates in a year.

Define the birthday function <span class="math">b:\mathcal{S} \mapsto \mathcal{B}[/spoiler] to be the map that sends a person to their birthdate. So everyone in <span class="math">\mathcal{S}[/spoiler] has a unique birthday if and only if the birthday function is injective.

Now we consider how many functions, and how many injective functions, exist between <span class="math">\mathcal{S}[/spoiler] and <span class="math">\mathcal{B}[/spoiler].

Since <span class="math">|\mathcal{S}| = N[/spoiler] and <span class="math">|\mathcal{B}|=365[/spoiler], it follows that there are <span class="math">365^N[/spoiler] possible functions, and <span class="math">\dfrac{365!}{(365-N)!}[/spoiler] possible injective functions.

Let A be the statement "Everybody in the set <span class="math">\mathcal{S}[/spoiler] has a unique birthday" (so P(A') is what we are actually looking for). By definition, P(A) is the fraction of injective functions out of all possible functions (i.e., the probability of the birthday function being one that assigns only one person to each birthdate),
which gives <div class="math">P(A) = \dfrac{365!}{365^N(365-N)!}</div>.

Hence, <div class="math">P(A') = 1 -\dfrac{365!}{365^N(365-N)!}</div>

Source: https://en.wikipedia.org/wiki/Birthday_problem

>>6721672
no, the most painless death would be swallowing a fistful of sleep pills, lay in shallow water face-down and use your arms to keep your face away from until the pills start working. You can listen to the music or an audiobook while you're waiting.

>>6721685
For f* sake.
Gott strafe LATEX.

>>6721610

That's just a function of two variables. I'm not sure if it's really considered calculus. Looks like this

http://www.wolframalpha.com/input/?i=x%5E2*sqrt%28exp%28y%29%29%2By*sqrt%28exp%28x%29%29+from+x+%3D+%7B0%2C+20%7D%2C+y+%3D+%7B0%2C+20%7D

>>6721692
Perfect.

>>6721694
I feel you, man

>>6721641

I'd personally go for overdosing on some drug, like heroin or something

>>6721610
it's exactly like f(x) = y, but you introduce two variables (x and y) instead of one and result is not y but z. Basically, when you pick a point on the plane, it have assigned value z in the space, just like in f(x)=y when you pick a point on the line, it have a corresponding point on the plane.

>>6720986
Continued from yesterday:

So what is Bayes Theorem?

It is the answer to the question "What is the chance that the ball is blue, given that you have called it blue?

p(u) = prior odds that the ball is blue (0.9)
p(a) = prior odds that the ball is black (0.1)
p(T) = odds that you guess true (0.7)
p(F) = odds that you guess false (0.3)
p(u|U) = odds that the ball is blue given that you called "blue."

p(u|U) = 0.9 54 54 54 54 <== We know from before
. = 6300/6600 <== That's how we calculated it
. = (9000*70%)/(9000*70% + 1000*30%)
. = divide by 10000 to get the right numbers
. = 0.9*0.7/(0.9*0.7 + 0.1*0.3)
. = p(u)*p(T)/ (p(u)*p(T) + p(a)*p(F))
. = 0.9*0.7/(0.9*0.7 + 0.1*0.3)
. = 0.63 / 0.63+0.03
. = 0.63 / 0.66
. = 0.954545454

p(u|U) = p(u)*p(T)/ (p(u)*p(T) + p(a)*p(F))

Or phrasing it slightly more like you'll find in a text book:

p(u) = base rate of blue
p(~u) = base rate of "not blue", where p(~u) = 1-p(u)
p(t) = test accurate
p(~t) = test not accurate, where p(~t) = 1-p(t)
p(u|T) = chance of blue given positive test

>>6722872

And then

p(u|T) = p(u)*p(t)/(p(u)*p(t) + p(~u)*p(~t))

>>6722876

So let us return to your problem:

>Event B has a probability of happening of 0.23
>But I have a probability of 0.8 of making the right guess
>If I guessed it was B, whats the probabilty of it actually being B, and not me being mistaken?

p(b|G) = The chance of the event being b given that you have guessed that it is b
p(b) = the base rate of b = 0.23
p(~b) = the base rate of not-b = 1-p(b) = 0.77
p(g) = the odds of you guessing right = 0.8
p(~g) = the odds of you guessing wrong = 1-p(g) = 0.2

p(b|B) = p(b)*p(g) / ( p(b)*p(g) + p(~b)*p(~g) )

p(b|B) = 0.23*0.8 / (0.23*0.8 + 0.77*0.2)
. = 0.184 / (0.184 + 0.154)
. = 0.184 / 0.338
. = 0.54437 ~= 0.54

>>6722872
What if we have the same original population of balls

0.9 are blue, 0.1 are black

and I have the same guessing as usual, 0.7 that I guess true and 0.3 that I guess false (0.7 reliability) and I call blue.

But then another guy with 0.6 of reliability calls black

And another guy with 0.333 reliability calls black too


Given our three guesses, whats the chance of it being blue or it being black?

Thanks for your illustration, I haven't seen a statistics course yet, but I stumbled upon this problem in a programming contest and its driving me nuts

I can now understand the
p(u|U) = p(u)*p(T)/ (p(u)*p(T) + p(a)*p(F))

But I can't now put in more than one person


The specific case for 1 person was
0.77 Red, 0.23 Purple
With 0.8 reliability I call Purple

so (0.8 * 0.23) / (0.8*0.23 + 0.2*0.77)
and I got the expected 0.544 of it being purple


Now there's a case with 3 people
0.6 Red, 0.4 Purple
A calls Purple with 0.9 reliability
B calls Red with 0.5 reliability
C calls Red with 0.6 reliability

Now what is the chance of it being purple?

>>6721641
Exit bag.
Google for details.

Is there any hope of eventually being able to predict radioactive decay of individual atoms?

>>6722998
yes

>>6722998
what would this be useful for?

>>6723007
Well for one QM tends to state it impossible..

Showing that impossible things are possible tends to be interesting.

Being able to predict opens up avenues for potentially influencing the process, controlling it and what have you, and that could be fun.

>>6723007
total determinism, we could predict the future

>>6723012
why would being able to detect the radioactive decay of individua atoms imply total determinism?

>>6723016
not really imply but definitely lead to, until we destroy the last bastion of randomness in the universe

>>6723016
no no, not detect; predict.

>>6723019
we'll also need to figure out when and where would pairs of particles appear out of the vacuum and annihilate

I get that we'd break the 'randomness' in decays, but from that to predicting the future is a long way heh

>>6723023
sorry yeah, predict

>>6723025
Every long way start with the first step, my friend.

>>6723026
All I hope is for some species existing during the 'lifespan' of the universe to figure out how to reverse entropy and fuck all, like pressing the reset button, and hope for another 'sentient thing' to do the same in the next iteration, keeping this shit alive

>>6723035
only if I become immortal, otherwise I'm fine with everything going to hell

>>6723038
I wish I was fine with that
Somewhat I care more about there being something complex, more than me being alive

Complex as in stars burning, planets forming, shit reacting, not just black holes and then when they evaporate just radiation perpetually going adrift

>>6722886

ugh.

The odds that it happened times the odds that they would guess those guesses if it happened DIVIDED BY the same plus the reverse - that is, the odds that it DIDN'T happen times the odds that those would be their guesses if it didn't happen.

>>6723062
fuck

anyway thanks for your help!

>>6723062
wait in the top table dont you have an error?
the population is 1000 balls but you have
the guesses adding up to 6000 and 4000 (5400, 600) and (3600, 400)

>>6723062

Oh god, all that work and I didn't even say the most important bit:

If you don't want to overload the function you're writing so it can take arbitrary number of tets, you can instead call it recursively.

I'm writing up some pseudo-c++ to illustrate this.

>>6723065

Yeah, there's a copy/paste error, I started out with 10000 picks but realized I only needed 1000 to fill my entire possibility space. (In fact, I only need 500 but 1000 is neater) but I apparently copied the top matrix from before I divided all numbers by ten.

Interesting bit here: It doesn't matter what number I write up there and, in fact, the "correct" number is 1. All your probabilities (when done) should sum to 1.

>>6723062
what are you into?
I'm a CS student (3rd year) but I have shit knowledge of statistics (we have it on the end of the year)

>>6723068
>I'm writing up some pseudo-c++ to illustrate this.


double baseRate = 0.6;

struct tester{
double testAccuracy;
bool guessedRed;
}

tester A = {0.9, 0};
tester B = {0.5, 1};
tester C = {0.6, 1};


double bayesTheorem(int baseRate, tester current)
{
double newBaseRate;

// what are the odds that this is red, given current.guessedRed?
//p(r|G) = p(r)*p(G) / ( p(r)*p(G) + p(~r)*p(~G) )

double pR = baseRate;
double pNotR = 1-baseRate;

if(current.guessedRed){

double pG = current.testAccuracy;
double pNotG = 1-current.testAccuracy;
}
else{

double pG = 1-current.testAccuracy;
double pNotG = current.testAccuracy;
}

newBaseRate = (pR*pG) / (pR*pG + pNotR*pNotG);

return newBaseRate;
}

baseRate = bayesTheorem(baseRate; A);
baseRate = bayesTheorem(baseRate; B);
baseRate = bayesTheorem(baseRate; C);

double oddsOfRed = baseRate;
double oddsOfNotRed = 1-oddsOfRed;

>>6723077

Be advised: I have not tested this thoroughly. It SHOULD work but I make no guarantees and, in fact, I have already noticed one bit of weirdness.

First test you should go through: Do you get the same result out if you switch up the order of the tests? You SHOULD end out with the same oddsOfRed at the end - you don't want to end up with different results depending on the order of evidence, if you do, I fucked something up.

My first run (Which I didn't compile, it was just in Excel) gave me the expected 0.8 when I ran the testers A, B, C but gave me 0.6 when I ran them C, B, A which should never happen.

I *think* the error was in my excel sheet but I frankly cannot be fucked to check.

>>6723076
>what are you into?

Education-wise: Electronics Engineering (Circuits and embedded programs)

Job-wise: Industrial Automation

But, and this is where I learned: Hobby-wise: Roleplaying (Them dice! Them stats! Them probabilities!) and AI (Them learning algorithms! Them evidence processing algorithms!)

>>6723062
>The odds that it happened times the odds that they would guess those guesses if it happened DIVIDED BY the same plus the reverse - that is, the odds that it DIDN'T happen times the odds that those would be their guesses if it didn't happen.

Phrasing this slightly better:

There are essentially two possibilities

It's RED, a is wrong, B and C are right.

It's notRed, A is right, b andc are wrong.

The odds of RED are

R = R*a*B*C/(R*a*B*C + r*A*b*c)

The odds of purple/notRed

r = r*A*b*c/(R*a*B*C + r*A*b*c)

Incidentally, you can here show that B (with the 50% chance) is useless by extracting him straight out of the function

B = 0.5
b = 1-B
b = 1-0.5
b = 0.5

b=B

r = r*A*b*c / (R*a*B*C + r*A*b*c)
r = r*A*b*c / (R*a*b*C + r*A*b*c)
r = b* r*A*c / (b* (R*a*C + r*A*c))
r = r*A*c / (R*a*C + r*A*c)

Oh hey, it's a formua that gives the same result without including a term for B, because he's a useless asshole.

>Stephen Hawking
he is just a hypocritical filthy scum, overrated, arrogent, self-centred, and an enemy to America (as he said he hates Israel)

All his work is pretty much useless now, and was never useful anyway, what has he even done for humanity? The State of Israel has done so much science, but this guy has done none

>>6723103
>and an enemy to America (as he said he hates Israel)

Cannot tell if /pol/ or retard.

>>6723106

hes a butthurt kike

>>6723112
wow big words, using the word kike on a scientific board. you fuckgin retard, you do realise, most of the nobel science winners were Jewish people?

Israel is the only nation in the middle east to do anything remotely scientific.

idiot.

>>6723112
>hes a butthurt kike

You think? I'm guessing false-flag >>>/pol/

>>6721071
some people haven't gone full faggot like you

>>6719114
BTFO
T
F
O

>>6723081
>First test you should go through: Do you get the same result out if you switch up the order of the tests? You SHOULD end out with the same oddsOfRed at the end - you don't want to end up with different results depending on the order of evidence, if you do, I fucked something up.

Turns out, I *could* be fucked to check.

As you can see, the end result is 0.2 chance of red for all orders of a/b/c

a is rated at 0.1 instead of 0.9 because he's not saying what the odds are that it's puple, he's saying what the odds are that it's not-purple.

(That is, 1-p(P) = 1-0.9 = 0.1)

This is because it's annoying to write out the if/then statements that flips his guess value so I just hardcoded it.

Also, again, because I cannot fucking harp on his lazy ass enough: The rate doesn't change after you ask B his opinion.

I've been doing CS for 4 years, since January 2011 and I will graduate on December 2015 (CS lasts 5 years in my University)

I was born in June 1992, so I'm 22 right now. I was among the oldest in my school's grade since I graduated at 18.5 (our school year starts at January and ends at December) so I started university at 18.5, meaning I'll graduate at 23.5

I'll finish CS, I love it, but now I've started Engineering Physics.. I know that its something I really like, but some people keep pressuring me for 'starting a undergrad at 22 and graduating at least by 25.5~26 from it while at that age I could already got a masters' considering that its in another University and there isn't that much transferrable credits between both Universities and Undergrads (so I can save a year at most)

I feel scared, I've been for a semester there, and sometimes I feel the joyfulness of a 18y/o that just got out of school and its all energetic for University, but other times a feeling like 'why am I going through all of this freshman/sophomore stuff again...'

>>6723137
Also, all these people with me all have like, 17, just a few 18, even if 22 is by no means old, I feel really old just being with them, like if I were in the wrong place.

test

>>6723137

100% fuck the haters.

I didn't finish my EE degree until I was 28 and protip: I felt old the entire time but I'm employed and happy with my job which is what counts.

THAT SAID

If you have a CS degree and can get a CS job, I'd recommend it (Unless you don't like CS obviously). Getting a "real" job changes your status from "student" to "adult" in a way nothing else does - not only in the eyes of the world but also in your own eyes. You're no longer fumbling through this weird student stage where you have all of the responsibilities of adulthood but none of the perks.

>>6723117
>Jordan, bitch

>>6720863
Doesnt that brake Newtons law? Every action has an equal and opposite reaction?

>>6723240

Newton's Approximation of the True Law, more like.

>>6723244
Yeah approximation, its never equal. Aome energy is always lost.

is the direct sum the exact same thing as the cartesian product?

>>6723156
I'd want a CS job while keeping on studying Engineering Physics, that would be awesome

The issue would be times, even part-times are difficult to make the class hours fit, and sadly in my 3rd world country there are no cool flexible CS-job-related-offices

Almost all CS stuff here is the old paradigm, no companies that make software of their own, but just software other companies need integrated into their business (support, databases, CRMs, ERPs, that stuff)

My dreamy CS jobs are outside the country, but at the same time if I go out, the chances of keeping studying Engineering Physics drop harshly.

>>6723240
Thats why it was surprising. A thrust without throwing something to the other side. For now the forces are minuscule, but its an application of vacuum energy not seen before, NASA is all proud of that shit

>>6723106

/pol/ would say he's a hero for hating israel.

>>6723400
>/pol/ would say he's a hero for hating israel.

Not if doing a false-flag "look at how stupid I can behave while pretending to be my tribal enemy" operation.

I mean, the position is clearly retarded. I just cannot tell if it's a retarded zionist or a poltard faking being a zionist.

>>6723392

Where are you from?

Also: If your CS degree is solid enough, you might be able to emmigrate to somewhere that'll let you do something fun with it. Absolutely 100% no guarantees though, there are shit jobs in all countries.

>>6723420
I think it is solid enough to attempt stuff anywhere, the thing is that I'm divided on the Physics thing and going out once I graduate CS. I still have until December 2015 to keep with CS and Engineering Physics, but once I reach that point I do not know what I will do, if I will continue studying or if I'll go abroad, considering that I both want a fun CS job and I want to keep studying physics.

>>6719114
>smart people
>MLK

It's funny that Negroes are so obviously inferior that we have to pretend borderline retarded plagiarists like MLK are great.

>>6721201

He's the only scientist to have a successful rap career.

https://www.youtube.com/watch?v=qrxbZwvCSUk

>>6723534
https://www.youtube.com/watch?v=TrOpoWEToaQ

why does something like (x+4)^2 not equal x^2 + 16? I understand the distributive property but I find it confusing as to why that doesn't work instead.

>>6724126
Basically because the ^2 isn't a "thing", it just represents (x+4) being multiplied with itself.

>>6724130
I like you. Thanks.

Why does this deer have a top hat? What is the science behind this?

>>6724140

>>6724126
This is a nice thread for you to read: http://math.stackexchange.com/questions/630339/pedagogy-how-to-cure-students-of-the-law-of-universal-linearity
Read all the answers carefully.

>>6720689
The universe seems to like equations with momentum and energy a little better than force. Force was just a trial run before it started thinking about more complex things like pendulums and light.

Go with the QM (the universe's latest idea on being edgy) idea of the momentum of light:
p=h*f/c

Anyone have any equations relating to feedback magnification. Like when you balance a glass of water without looking the water moving will amplify the corrections until you spill it.

>>6721610
Yeah... uh not really calc...

>>6721156
it was
how else would he respond so fast. it takes him hours to encode that shit

My stupid questions:

Why do many substances (all?) have discrete boiling and melting and freezing points where they change state, rather than continuously becoming more and more dense as temperatures decrease? Like, why do I have liquid water until I hit 0°C, at which point I get solid water, instead of getting water that's continuously and gradually more and more solid as it gets colder? Why don't I have Jell-O water at, like, 6°C or something?

What do mathmeticians actually do? Is there even a job or role where somebody just does math for a living, or are there only fields of applied math, like cosmology and engineering and shit?

>>6724144
because she's british as fuck

>>6720689
when you gotta go fast, then you gonna get mass

>>6724254
solids can have different phases within the solid phase at different temperatures and pressures, for example the ten or so different solid phases of ice.

>>6724254
it takes energy just to change state, so when you heat the ice it uses the energy to turn into water first, then start storing energy as heat.

>>6724254
>Why do many substances (all?) have discrete boiling and melting and freezing points where they change state, rather than continuously becoming more and more dense as temperatures decrease? Like, why do I have liquid water until I hit 0°C, at which point I get solid water, instead of getting water that's continuously and gradually more and more solid as it gets colder? Why don't I have Jell-O water at, like, 6°C or something?

What happens exactly is that, if you heat ice (for instance) , once you hit the melting temperature, the ice starts to melt, but the temperature does not vary. That is, you keep heating the ice, which stays at the melting temperature, until all of it has become water -- then water's temperature increases. So in that sense ice and water coexist at the meling point !

Now you ask: why doesn't ice exist at higher temperatures (or water at lower temperatures). The (short) answer to that is that to determine the ground state of a system (with constant external pression) one has to minimize its free energy

F = U-TS

where U is the internal energy and S the entropy.

For the liquid phase U is higher than for the solid phase (as the ordening of particles in the ice allows to minimize the interaction energy) and S is lower in the solid phase (as there are less configurations available).

That means that for low temperatures (inferior to the melting point) the energy of the solid phase is lower and thus it is the only stable and for high temperatures the entropic term dominates and it is the liquid phase that wins. The phases of higher energy are not stable (algthough they can exist under specific conditions -- see metastable ice.

>>6724765
in other words, at certain point molecules in the substance move so fast that they are not constrained by the pressure or bounding forces anymore.

>>6724769
basically yes but that is somewhat imprecise (this does not explain why the process is discontinuous). and you forget the role of entropy -- the phase transition occurs because there are many more available liquid states than solid ones.

>>6719603
Marsden was pretty good - worked for me as a physics student - but not pedant mode, which seems to be what you want. Generally VC is for physicists and engineers who don't want that.

Looking at Apostol he also covers a lot of other ground.

>>6719280
This is a brilliant idea and will work well.

Can anyone with Matlab at hand post the output of `magic(10)' and `magic(12)' please?

>>6719102
Can anyone recommend a good "Geology 101" text book? I just want to get a good overview at the level of the first geology course you might do in college. Math is no problem for me.

How fast would something have to go for air friction to get high enough that water's condensing on it? How about a brick for an example?

>>6724964
0m/s using a brick at the temperature of 0K

>>6724935
Used octave instead but should be the same

octave:1> magic(10)
ans =

92 99 1 8 15 67 74 51 58 40
98 80 7 14 16 73 55 57 64 41
4 81 88 20 22 54 56 63 70 47
85 87 19 21 3 60 62 69 71 28
86 93 25 2 9 61 68 75 52 34
17 24 76 83 90 42 49 26 33 65
23 5 82 89 91 48 30 32 39 66
79 6 13 95 97 29 31 38 45 72
10 12 94 96 78 35 37 44 46 53
11 18 100 77 84 36 43 50 27 59

octave:2> magic(12)
ans =

144 2 3 141 140 6 7 137 136 10 11 133
13 131 130 16 17 127 126 20 21 123 122 24
25 119 118 28 29 115 114 32 33 111 110 36
108 38 39 105 104 42 43 101 100 46 47 97
96 50 51 93 92 54 55 89 88 58 59 85
61 83 82 64 65 79 78 68 69 75 74 72
73 71 70 76 77 67 66 80 81 63 62 84
60 86 87 57 56 90 91 53 52 94 95 49
48 98 99 45 44 102 103 41 40 106 107 37
109 35 34 112 113 31 30 116 117 27 26 120
121 23 22 124 125 19 18 128 129 15 14 132
12 134 135 9 8 138 139 5 4 142 143 1

>>6724970
Thanks, mate.

>>6719102
Is there really a difference between the 6th and 7th editions of "A First Course in Abstract Algebra" by John B. Fraleigh.

Also, why do these authors need to release multiple editions of the same text?

>>6724989
>Also, why do these authors need to release multiple editions of the same text?
Fix typos and mistakes (ie. erratum)?
Clarify or explain better some sections (using feedback from previous editions)?
Extend copyright?
Make more money with the same amount of old work?

>>6724989
>Also, why do these authors need to release multiple editions of the same text?

Because if the professor requires you to get the 7th edition, you cannot buy the 6th edition used (and give no money to author or publisher), you have to buy 7th new (and give etc.)

Probably very elementary, I just don't get it.

>>6725002
forgot pic

>>6724937
Are there so many virgins in Physics that it's out of the chart?


Anyways, can I do something like a mathematical finance PhD after studying a masters in theoretical physics?

>>6725002
forgot pic

>>6725008
Just check if they're linearly independent. If you can get a combination of v1 and v2 to form v3, they're linearly dependent, hence v1 and v2 only span a plane, or R2.

>>6725007
over 100% of physicist are virgin

I am somewhat bad at math. I understand a lot of the logic behind it, but I have been a lazy motherfucker for the longest time in school. Is there a way to start learning math again that wont be too boring? I just want to be able to explain the most important aspects to my kids one day.

>>6725038
there is no way it won't be boring unless you are a math geek

>>6719102
Where does short term memory end and long term memory begin?

I find it difficult to recall things I studied 3 months ago, how do I ensure this does not happen?

I'm a pleb who dropped out of high school.

I'm interested in a 4 year degree in computer science. How long would it take me to get up to speed, mathwise?

inb4 /adv/, they suck and this is a stupid questions thread

>>6725359
A very long time.

I have a question,
If B is a subset of A, how B-A would be represented in a Venn diagram?

I don't really understand colour as a property of material.

It basically involves the fact that some atoms/molecules absorb light of certain frequencies. So if a sample absorbs a set of frequencies, FreqA, say, then an interaction of the sample with white light gives:
(Complete set of freqquencies, white light) - (FreqA) = Freq B. And what we see is the colour corresponding to the set of frequences, FreqB, that was reflected and not absorbed.

If that is correct, I wonder what happens to the absorbed frequencies, FreqA, in the material. What do they interact with in order to be absorbed? Electrons? But then if those excited electrons de-excite, emitting FreqA into the atmosphere again, presumably we get back FreqA + FreqB = white light, and we would just see white light again. Or do they disperse as phonons in the material? Or are they indeed emitted back into the atmosphere, but isotropic in direction, and so barely noticeable?

This is probably a very stupid question.

>>6725419
however you represent the empty set in venn diagrams.

>>6719110
>>6719102
kek'd
based professor of truth

>>6719290
>Can I use the scientific method to find the perfect girlfriend?
You mean "how to find it?" or "How can i choose it?" or both?

How does the laplace transform work? I can apply LT and its inverse, have learnt proofs, definitions etc, but I never got the intuition on how the fuck it works and how did Laplace come up with it. "Let's try this to simplify stuff, oh shit it worked" or what?

>>6725430
when electrons of certain atom on a specific orbit "de-excite", they always release the same amount of energy/frequency.

>>6725491
>"de-excite" to a specific lower energy level
fixed, electrons don't always fall down to the same energy level

>>6719102
that op pick, next move is on the comic guy, what does he say (could say to be funny)?

>>6725510
yep, that's exactly what I wanted to say, thanks. I also should have mentioned that they do it by jumping into an orbit closer to the nucleus.

>>6721540
The chance of not happening is P=(0.99)^100=36.60%
The chance of happening at least once=1-P=63.40%

>>6725430
I'd say that the light absorbed by the electrons is converted into heat through complex processes within the solid (interactions, phonons, etc)

That heat is (at least partially) reemited towards all directions through thermal radiation which spectrum is decorrelated from that of the incident light.

Note that this is different form some materials (metals) being"shiny" (reflecting light)

>>6725259
>where does short term memory end and long term memory begin

Answer this you hobos.

>>6725259
Overnight.
Get better study strategies.

If the force and displacement vectors are not collinear you calculate work with the projection of the force vector onto the displacement vector, rather than the original force vector.

...why?

Money when??

>>6724995
Typos and erratum are dealt with in printings. The process is this

1. Lecturer requires students to have the latest edition, by picking exercises from the latest edition (only - maybe the exercises change maybe just their order or other minor details).

2. Publisher gives lecturer kickbacks for doing this.

>>6726070
Testing

>>6719102
Explain to me the theories of why/how virtual particles exist.

>>6719580
My understanding is that it throws off Cerenkov radiation (i.e. one photon -> 2 photons), thereby conserving energy/momentum.

>>6726187
>how virtual particles exist

HAHAHAHHAHAHAHAHAHAHA, no. They don't exist.

So what's the deal with magnets?

>>6725895
I knew the answer but I forgot.

>>6726221
>virtual particles don't exist
idiot

>>6726187
basically some physical pemomenons behave like particles (they share the same statistics for instance) so they are called "particles"

see : photons, phonons, ...

>>6726331
>mathematical concepts exist
idiot

If I do a series of N measurements where the amount of 'succesful' events <span class="math"> \nu [\math] is given by the binomial distribution, and I repeat these series M times, obtaining answers <span class="math"> \nu_1 , \nu_2 , \nu_3 ,..., \nu_M [\math]

How do I use the principle of Maximum Likelihood to estimate what the probability for a succesful event p is?[/spoiler][/spoiler]

>>6726480
Yes

Are element names proper nouns?

Do I write titanium or Titanium?

>>6726509
do you write gold or Gold?

>>6719494

google the birthday paradox

>>6726509
http://lmgtfy.com/?q=do+you+capitalize+elements

Why is the opposite of a Proton called Neutron and not Contraton?

If nothing can than the speed of light then how does gravity escape black holes?

>>6726634
opposite of proton is called anti-proton, opposite of neutron is called anti-netron

/sci/ I'm about to start my second year of pre-pharm. If I don't get in to a pharm school, what major should I switch into to make money in busyness or industry? Biostat?

>>6726646
go to the gym, in 30-40 years most of the office jobs are going to be replaced with scripts.

>>6726650

ok, so lets say I want academia, then what should I do?

>>6726651
make sure you are the one making the scripts, just like me. I'm after 2y of econometrics with some programing on a side and eco didn't helped me with this a bit so far. Make of it whatever you want.

>>6726636
it doesn't, gravitons keep flowing in, dragging everything with them

Last time I checked, relativistic physics and quantum mechanics were incompatible and combining them will be like the most important event to happen in science. So what's the deal with LQG and string theory?

>>6726480
fuck, retry

If I do a series of N measurements where the amount of 'succesful' events (v) is given by the binomial distribution, and I repeat these series of measurements M times, each giving a number of succesful events (v1, v2, v3,.. vM)

How do I use the principle of maximum likelihood to estimate the probability p?

>>6726731
Use the MLE:
Set up a probability function of your result. Take logs, differentiate and set to zero, solve for p.

Then differentiate again and show that it is negative for p=p` (in this case it should be negative for all p), thus it is a maximum.

>>6726759
The probability function is just pic related then?

>>6726764
v/nu should have subscript n

>>6726764
yes.

Simply put, let's say you get the values 2 and 4. The probability of this result is P(n=2)*P(n=4) which you would sub in the binomial function for each point. Then you try and maximise this probability by changing p.

After the first Op amp there's a rectangle with a weird curve and an arrow.
What is?

Also what do you adjust on an op amp

How do these things steer?

Up and down I get with the heating of air but sideways? Do they just go with the wind until they find a field large enough to land on?

>>6726790
they can't steer

Mathworld says the spherical area element is <span class="math"> r^2 sin( \theta ) dr d\theta d\phi [/spoiler] How can this make sense unit wise? Does it just work because you're going to set r=R before the integration?

Using sig figs in "large", multistep equations like (25.429 * 26.555) / (52.0 + 256.42), do you round the numbers after each component is done, or only for the last problem you solve?

>>6726821
That is volume element. Sphere element is <span class="math">r^2 sin( \theta ) d\theta d\phi[/spoiler]

>>6726837
http://mathworld.wolfram.com/SphericalCoordinates.html
Equation 14 they list the same which is why I'm asking.

>>6719110
>>6719102
Seems scripted.

Do all variational problems with certain boundary conditions have solutions?

>>6726854
of course it's scripted, it takes minutes-hrs for him to from longer sentences

>>6726772
thank you!

Is there a set of equations where I can calculate how far away an object of 'a mass, b material, c volume/shape' can be before an electromagnet of 'x guass/Tesla' takes hold of the object, and how much acceleration the magnet will impart on the object before reaching the midpoint?

>>6726829

last step.

why this tread still alive ?
in /b/ this would be hapend

Is it possible to comparatively analyse epigenetic changes in blood from a newborn sample with that of my current blood.

>>6727083
>in /b/ this would be hapend

And the inhabitants are called /b/tards. You will find that there are many differences between the boards.

>>6727091
>Is it possible to comparatively analyse epigenetic changes in blood from a newborn sample with that of my current blood.

Not as a home project but as something you can get somebody to do for you? Yes.

>>6719102
Does he ever brush his teeth?

>>6726837
How to make different font slanted text? Is there some sort of short cut on my keyboard?

>>6727106
<span class="math"> like this [/spoiler]

>>6727106
[math ] [/math ] tags
remove the space
>>6727107
need to put a space somehow. maybe
<span class="math"> like\: this [/spoiler]?

I have never understood the trigonometric functions. Am I special?

>>6727111
no, there's plenty of you out there. you're special to me though because I make money off of you.

>>6727119
Bully

What are electromagnetic waves really? I mean, really?

>>6727127
Jew magic, essentially.
Think of it like strong water currents that only interact with ferrous materials.

>>6727122
life aint easy niggas gotta eat that's when shit gets greasy

>>6727133
Bully

Why do I prefer the smell of my own shit to others?

>>6727146
because you know it's yours.
If you're presented with two shits without knowing if they're yours or not, you'd be equally disgusted (or turned on, I don't know you)

>>6727150
This is shit.

>>6727151

What if God was one of us?

>>6727162
Then everything suddenly makes a lot more sense.

Why does the stuff under my toenails smell like cheese? And why does it have that gritty texture when I eat it?

What if programming was like maths in motion?

>>6720689
but photons have mass, u w8 m8