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Archived threads in /sci/ - Science & Math - 402. page


What's the probability that a coin ends up on its side in a coin toss?
21 posts and 1 images submitted.
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depends on the thickness of the coin you fucking retard.
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>>7805084
Doesn't it depend on the relative position of the moon?
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>>7805084
Oh yeah? And what equation, theorem or peer-reviewed paper supports that?

Sup /sci/

I have the opportunity to graduate with two degrees in chemistry and mathematics.

I've taken enough classes and earned enough credits to get BS degrees in both however my college is really bizarre and will let you graduate with only one BS degree (the other has to be BA, MS, etc.).

So my question is this:
Should I graduate with a BS in Chemistry and a BA in math or a BA in Chemistry and a BS in math?

I'm not really sure if BS vs BA makes a difference in the job market.
12 posts and 1 images submitted.
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>>7804478
I'm gonna go out on a limb and say get the BS in Chemistry. There are a lot more industrial applications, and if you're American, you can become an ACS certified chemist with a BS (I believe you can't with a BA). A degree in maths will look good no matter what.
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>>7804478
>I'm not really sure if BS vs BA makes a difference in the job market.
It probably doesn't, but I'd go with BS in chem, personally.

More importantly, wtf is going on in that pic?
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>>7804514
>A degree in maths will look good no matter what.
I feel kinda gypped though. I've earned enough credits for two BS degrees :(

Does the ACS certification really matter that much?

>>7804515
>It probably doesn't, but I'd go with BS in chem, personally.
That's what I was leaning towards. Chemistry is a science and math is an art so it only makes sense to do a BS and BA in the respective fields.

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When did functional analysis turn into a meme field?

>we already have a large zoo of function spaces
>b-b-but muh functions with this property are so special, they deserve to have their own function space with its own special name and symbol
>let's prove theorems about them, just for the sake of having proven theorems about them
Literally biology tier at this point. Every idiot thinks the can make up his own category regardless of whether it's meaningful or not. Enjoy your stamp collecting, functional analysis fags.
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Tfw math will advance so fast in your lifetime that there's absolutely no chance of learning it all
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>>7804233
It already has. Where have you been for the past few decades?
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>>7804239
Nah, it was like that for hundrets of years. Of course, at some point people came and cleared up subjects and made them accessible from simpler perspectives. There are so many many topics with hundrets of papers on them that people lost interest in and nobody today really knows about them.

e.g. you never learn much about
https://en.wikipedia.org/wiki/Heap_%28mathematics%29

and that's at least a simple to define algebraic concept. Things like

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

are cooked up and lost in time. Those things survive that solve age old problems and you never hear about the thousands of mathematicians that tried and failed

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Is Banking a Science?
9 posts and 1 images submitted.
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>>7804122
uses economics and maths and psychology and statistics and comp sci., so I guess you could argue it's a mixture of a ton of different sciences
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>>7804122
Bump for science!
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banking is not a science in the same way that car mechanics is not a science

you are not explicitly _investigating_ something. and whenever you are learning something new about your topic, it is not about a natural system but a manmade system. you may say that science also studies man, of course, or that the product of human interactions, yes. but banking is not the study of this, economy is a study of something like this, but banking is a profession not a science

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Is it normal to get urges of extreme anger, frustration, despair, murderous and genocidal thoughts if one cannot solve a math problem even after reading through the books, watching youtube vids and searching on google?
7 posts and 2 images submitted.
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>>7804093
Yes. But apparently that's a sign my ego is too big to learn properly, so I'm trying to fix that.
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>>7804093
well it seems
f(y,p) = f(y|p) * f(p)
y|p ~ binomial (n, p)
p ~ beta (alpha, beta)

you're looking for f(y) so you integrate f(y,p) for all possible p's.
You use the fact that the integral from 0 to 1 of
p^(x-1) * (1-p)^(y-1)
is gamma(x)*gamma(y)/gamma(x+y)
and you obtain the resulting distribution for f(y)
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>>7804093
Except the murderous part yes. Welcome to mathematics! As an aside, this also happens in applied theory, when no one has ever asked a question similar to yours and you have to do all the findings on your own.

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How do you organize and name your papers?
16 posts and 2 images submitted.
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making a lot of assumptions there
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>>7803955
Jesus that looks tedious.

Just use Mendeley.
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>>7803955
>>7803955
i don't bother renaming each individual paper as i have thousands of them

I just have different folders for the different topics i'm interested in and save papers in there

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What are the best mathematical books? What do you recommend?
20 posts and 3 images submitted.
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Not OP, but let me make a different question: How can I identify/know which books are horrible for learning? There's thousands of books for math, for example, how can I know which is good and which is not? Amazon reviews are not the best source for this, sadly.
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>>7802304
If it's a Pearson book it's complete and utter garbage and you shouldn't spend a penny on it. Don't let anyone tell you Pearson publishes any good textbooks, some cucks may throw University Physics by Young at you, but it's an awful book and just happens to be the book they were pigeon holed into in their high school physics class and so it's the only book they've ever read.
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>>7802304
>>7802816
samefag

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Sorry for the retarded question, but isn't pi:

4/1 - 4/3 + 4/5 - 4/7 + 4/9 - ... = Pi

Similar to:

1/2 - 1/4 - 1/8 - 1/16 - ... = 0

Pi, like 0 will have a number you can write out completely, we just don't know how to work out the exact circumference of a circle so we use approximations.

Am I right in thinking this, /sci/?
30 posts and 2 images submitted.
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>>7802104
So, how is high school going? Still trolling le /b/?
>>
>>7802110
So it was a retarded question? I'm sorry, anon, but can you please tell me why it's retarded?
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>>7802110
You're the one that sounds like you're in high school.

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Here is one step of a possible synthesis of methylphenidate.

I get it that tert-butoxide removes a proton from piperidine, alpha to the nitrogen.

Then the carbanion hits the tosylhydrazone, a pair of electrons shift from the C=N to a N=N double bond, but then...

Does the tosyl moiety leave? 'Cause tosylate is a good leaving group, but the tosyl doesn't look like one. What else could happen?

>Also feel free to recycle this thread into a general orgo question thread once we're done with this particular question.
40 posts and 4 images submitted.
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>>7799815
maybe the conj. base of tosylhydrazide is the leaving group
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>>7799856
>conj. base of tosylhydrazide
That's a dianion, right?
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Same question in picture form.

The other one is 300+ so starting new one

I'll start:

How the hell do you guys keep up with all that terminology in probability theory?
Namely, how do you tell apart and remember those: Probability distribution, probability mass, probability density, probability distribution function, probability function, cumulative density, cumulative distribution function
321 posts and 27 images submitted.
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>>7795379
It might help if you disregard the word Probability in all those. If a probability theory question pops up, you just imply it includes that and not just ordinary "mass, density, distribution" etc
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>>7795379
the names are pretty clear
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when talking about sets
if you have, for example, [math]F^E[/math], what does that mean?

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Has anyone here dropped out/failed college and then came back later and succeeded?
12 posts and 1 images submitted.
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Yeah, I dropped out of college and joined the military. Now I get like 74k/yr accounting for the benefits and all for doing almost nothing and I'm in charge of almost 24 other people. I command them to do busywork some other asshole told me to tell them to do.
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>>7806121
Okay, I'm done. I need the truth. In just this week I have seen like 3 posts of people saying that they went to the army and then went to college for free and now live the easy life.

What the fuck? Are you the one who has this experience and you are just posting it over and over again? Are there actually a bunch of military 20 something fags here in 4chan?

Or is it as I suspect, that the US government has started recruiting in 4chan. If this is true then m8, the kind of soldiers you will get from here will need a lot of training before you get them to do anything.

Initially, you will have to train them not to stare at their commanders fat cock.
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>>7806112
i was an arrogant faggot and tried to get a physics degree as quickly as possible but realized i was being stupid too late and failed out. Now I'm studying information science and CS and am doing much better. It's probably not what you were looking for but I think my mistake can be valuable to learn from.

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What do I square root to get an irrational number that has all the primes in order?

For example:

2.35711131719...
25 posts and 1 images submitted.
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not sure, but something something fermat, something something cuberoots

also fuck off
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>>7806109
>also fuck off
r-rude
>>
I'm guessing it's a number less than 9 but greater than 4.

Any ideas, /sci/?

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A couple of days ago anon posted pic related. There's a lot of stuff I don't understand here...

>eta
is this just a variable anon is using, or some special kind of tensor?

>f, out of fucking nowhere
where does this come from? am i misreading it as a j?

>rules for working with upper/lower indices
when can a kronecker delta be combined with some other tensor to "eliminate" a variable?

>index forms for div, grad, curl, laplacian
can someone recommend a good reference for finding these?
4 posts and 1 images submitted.
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>eta
In the way it's written, paying some heed to up/down indices, it's written as if you'd be working with a space equipped with a metric to move between the vector space and its dual. Briefly, it's used to raise/lower indices, but the upstairs/downstairs (contravariant, covariant, or mixed indices) Kronecker deltas are exactly the same anyway.
>f, other indices out of nowhere
If you're working in Einstein notation, which this is (please Google it if unfamiliar, it's pretty straightforward), repeated indices are dummy indices--so it could be replaced with any variable you wish, as these are summed over and not actual indices of your final expression.
>rules with upper/lower
This explains the previous confusion, upper and lower matter if you're working with a metric. If you're not sure what a metric is, it's essentially a way to relate a vector with upstairs indices to a mathematical objects containing the same information with downstairs indices. Please refer to Einstein notation again, I think this clears up the confusion with kronecker delters eliminating variables (indices?).

>index forms for grad, etc.
They're straightforward to understand/work out yourself once you see the rules. The epsilon symbols you're seeing are referred to as Levi-Civita symbols (sometimes permutation symbol, antisymmetric symbol) and have properties closely related to the definition of determinants and cross products. The other index notations will be obvious once you spend some time working with it.

You'll do well to look up Einstein notation and maybe some older mechanics books that have a section on it.
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I'm not 100% sure what exactly the context for this stuff is but I might be able to help.

>eta a variable?
Eta could refer to the metric tensor. That's usually what we reserve it for. It is not a variable though

>f out of nowhere
I think they may have meant for that to be an "l" but you should really be able to follow along at that step to see what's happening.

>kronecker delta
that's literally what it does

>help with the indexing for the diff operators
I'm pretty sure the book Div Grad Curl and All That goes into this notation. I learned it before reading the book so I don't remember.
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>>7806059
>Eta could refer to the metric tensor.

Specifically, eta usually means the Minkowski metric tensor.


>>7805995
Is you just want to learn this type of index stuff, go through a relativity course. Probably the best place to pick it up.
http://theoreticalminimum.com/courses/special-relativity-and-electrodynamics/2012/spring

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What's the loudest sound possible? If there is a limit, why can't it be passed?
19 posts and 2 images submitted.
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https://www.reddit.com/r/askscience/comments/25q8o0/is_there_maximum_as_to_how_loud_a_sound_can_be/
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In principle, there's isn't one. But at a certain point, the medium propagating this sound wave I guess could be completely displaced and it would no longer really be a wave at all. That's sort of what happens in pic related, but the wall of air rushing at you (that hasn't been turned to plasma) is like a sonic boom and not really a sound wave. If you watch the old videos of nuclear tests, you'll notice that after the wind tears by, it all comes rushing back in because of the huge pressure differential.
Again, not really a sound wave.
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>>7805937
No upper limit, really. The loudest recorded sound was some volcano going off, it ruptured eardrums miles away.

https://www.youtube.com/watch?v=SauQYUJ2Ckw

Not the same thing, but you get the idea.

So, if you were inside a planet made entirely out of iron-nickle and it was struck with similar planet going at .4 the speed of light, it'd be very loud.

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What's the evolutionary advantage to having large feet?
I can't really think of what benefit it could possibly give other than maybe faster swimming or kicking things, but for that most kicks in martial arts are done with the shin rather than the foot.
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>>7805900
Larger feet = better balance
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>>7806015
/thread
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>>7805900
>heel kick
also, people with bigger feet have bigger calves, as it gives you that extra bit of push on your gait.

also, for boxers, it makes you punch marginally harder, given the extra bit of push you get from your calves. (believe it or not, any punch in boxing uses the whole body, thats why they hurt so much)

tl;dr bigger feet = bigger calves = more power

also better balance etc.

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