Quantcast
[ 3 / biz / cgl / ck / diy / fa / g / ic / jp / lit / sci / tg / vr ] [ index / top / reports / report a bug ] [ 4plebs / archived.moe / rbt ]

2017/01/28: An issue regarding the front page of /jp/ has been fixed. Also, thanks to all who contacted us about sponsorship.

/sci/ - Science & Math

Page 2


View post   

[ Toggle deleted replies ]
File: 12 KB, 480x360, IMG_3970.jpg [View same] [iqdb] [saucenao] [google] [report]
9542664 No.9542664 [Reply] [Original] [archived.moe]

Why do stars look like this through the lense of a p900

And why are all the NASA photos of stars and planets all enhanced with photoshop

Not looking for conspiracy theories saying that just curious

2 replies omitted. Click Reply to view.
>> No.9542683

Could be an imaging problem that resulted in something cool but that is not a normal example

>> No.9542777
File: 7 KB, 215x168, IMG_3954.jpg [View same] [iqdb] [saucenao] [google] [report]
9542777

>>9542683
It seems to be happening on every ones p900

Pic related is from a friends camera

And I've been looking on YouTube and most look like this
https://m.youtube.com/watch?v=DbLu9fcQI4w

I understand what you sort of mean though the camera most capture all them light waves in a different way compared to specialised cameras

What do they really look like from high powered NASA type cameras or telescopes? Any good images of them what haven't been shopped a little for that hint of aesthetics they like to add on to most photos ?

Btw I haven't used one of the p900s

>> No.9542834

>>9542664
>Why do stars look like this through the lense of a p900
Because the P900 is a shitty camera.

>> No.9542836

Oh, I found this video which is probably better explains it. Basically the dumb fucks operating those cameras can't even focus properly (probably focusing somewhere near the closest focusing distance instead of near infinity) which causes the light to scatter a lot onto the sensor.
https://www.youtube.com/watch?v=dICIKYn5w4w

Knowing how to use your tools is important.

>> No.9542840
File: 65 KB, 1280x1280, eso-antares-image.jpg [View same] [iqdb] [saucenao] [google] [report]
9542840

>>9542664
Distortion from the lens and from atmospheric refraction. The lens on the camera isn't perfect, so it distorts the shape of the basically point light source that a distant star would appear to be from such a small lens. Atmospheric is far less uniform in density and temperature than the camera lens, and further distorts the image. Dust in the air easily discolors the light.

Pic related is best pic of distant star we have. Spoiler: it looks a lot like the sun. Now of course, not all stars look so much like our sun, but besides change in color or size, most likely look basically the same.



File: 134 KB, 600x902, Discriminant-Analysis-of-Principal-Components-DAPC-to-infer-population-substructure-A.png.jpg [View same] [iqdb] [saucenao] [google] [report]
9542622 No.9542622 [Reply] [Original] [archived.moe]

Hello /sci/, how do I learn about PCA? I have a classification problem and I know PCA is probably the best way to sort it out given the data I have. I have an intuitive understanding of what PCA is (taking a big data cloud and finding the axis with the most variance) but I need to understand its nuances as a tool so I don't make any dumb mistakes and can talk to stats experts in a knowledgeable way. I also need to understand clustering better. Any book/article recommendations about how to use PCR as a tool without getting too bogged down in the theory?

>> No.9542662

Pca isn't a classification tool though. You can use it to do am external check to see if a given set of parameters might work as a classifier but it doesnt have a way to do any of the things classifiers do

Anyway as a rule of thumb if you have a classification problem, throw random forests on it and see if you get anything. If random forests can't do anything with your data you might as well stop

>> No.9542695

>>9542662

Sorry, I wasn't specific enough. I want to do PCA then do some type of clustering. I don't know about random forests but they look like they would solve the problem as well. What's a good resource to learn about them?

>> No.9542698

>>9542695
None come to mind but I'm pretty sure some googling will pull up python and r packages. Best way to learn is doing.

>> No.9542890

>>9542622

PCA is a dimension reduction / variance explanation tool. It's useful for multivariate analysis to project your data into orthogonal (i.e. "independent") components. Each component is a linear combination of your original variables. If your dataset has correlated variables, it seeks to combine those variables into a supervariable that best explain their variance. Then, it seeks another supervariable to explain the rest of the data and so on. It's just a variable combiner; a way to make your dataset smaller. That can be useful in some machine learning problems (like basic clustering) because it reduces the number of variables / dimensions to a manageable and interpretable size.

However, it often performs shittily on real datasets due to strong constraints (like orthogonality). There are better tools out to there to reduce dimensionality while taking into account the "shape" of data (e.g self-organizing maps).

As for clustering, pre-conditioning your data with a dimension reduction technique like PCA can definitely help if you suspect many of your variables are correlated. It can help with classification too. Just be aware of what your transformed variables actually represent to gain intuition about what you're doing.

>> No.9542905
File: 91 KB, 600x378, Druidbro.jpg [View same] [iqdb] [saucenao] [google] [report]
9542905

>>9542890
this. PCA is just about squishing down a big nth-dimensional data set into two or three dimensions so you can visualize it better and identify which variables actually contribute significantly to variance. (good rule of thumb is any principal component that doesn't explain >10% of total variance isn't important.)
actual cluster analysis requires further techniques; PCA just isn't about that.

t. guy who did relative warp analysis (PCA for morphometrics) for his thesis.



File: 30 KB, 220x165, IMG_0590.jpg [View same] [iqdb] [saucenao] [google] [report]
9542596 No.9542596 [Reply] [Original] [archived.moe]

What your thoughts on EE?

8 replies omitted. Click Reply to view.
>> No.9542988

>>9542974
EE/CE is literally poverty- and brainlet-tier if you aren't in a semiconductor-related field.
And you need a master's at a minimum to touch IC design, with PhDs preferred.

>> No.9542989

>>9542611
Not as brainlet as CS

>> No.9542991

>>9542980
>I'm not bragging though. It was a simple joke but the way you guys have responded over it speaks volumes
i dunno man, you seem upset

>CS is more marketable I went that route instead.
might as well have went into finance or some other bullshit then. marketability does not give you bragging rights on /sci/

>I don't think highly of CE though but that's for completely different reasons.
CE is the best degree if you want to do CE. plenty of EEs end up going into CE and realize they wasted tons of time learning optics and E&M and other shit they didn't need. CS can't into CE at all. some CEs end up as software developers so yeah they should have just went CS cause its easier and you'd get more software dev experience. CE is like aero in that if you want to design spacecraft its the best degree, but if you end up being some HVAC faggot you might as well have just done ME.

>>9542988
>if you aren't in a semiconductor-related field
if you aren't in a semiconductor-related field then you aren't in CE at all. also i have a PhD. for most STEM degrees you aren't really likely to work "in the field" without at least masters

>> No.9543020
File: 67 KB, 310x456, trades stem humanities.png [View same] [iqdb] [saucenao] [google] [report]
9543020

It's a trade.

>> No.9543032

>>9542991
>make joke
>people get butthurt over it
>point out I like EE to calm the butthurt
>"y-you're the one that's upset"

The more you post the more insecure you look. Once more you bring up bragging over a joke. CS is more marketable then finance. Plus I do like CS, I didn't just pick it for job prospects.


"CS can't into CE at all"
I literally could into some jobs. CE varies per uni, in mine CS and CE are practically the same thing (granted the full title of my major is computer science and engineering but still).

Not like I would ever want to though, there are barely any actual CE jobs so you'd be stuck doing CS or EE. You'd go into either field with a disadvantage over others. Also calling CS easier the CE is pretty ignorant but, well, not like you've shown otherwise. You're a PhD so maybe you like research and all but for those of us who just want a job CE carries too many disadvantages that the shallow knowledge you get in either field isn't enough to make up for it. In the masters level its pretty good though.



File: 639 KB, 1200x1259, Metallicity.jpg [View same] [iqdb] [saucenao] [google] [report]
9542547 No.9542547 [Reply] [Original] [archived.moe]

Is it possible that as the Universe gets older, Metallicity in stars will increase and outnumber Hydrogen and Helium stars? And if so, when will this happen?

>> No.9542555
File: 48 KB, 483x593, skwisgarr.jpg [View same] [iqdb] [saucenao] [google] [report]
9542555

It's gonna be pretty fuckin' metal.

>> No.9542591

What would happen, if a matalic star collided with a magnetar?

>> No.9542680

https://en.m.wikipedia.org/wiki/Iron_star



File: 2.01 MB, 3996x2995, 516627549.jpg [View same] [iqdb] [saucenao] [google] [report]
9542544 No.9542544 [Reply] [Original] [archived.moe]

I'm in space ama

8 replies omitted. Click Reply to view.
>> No.9542858
File: 175 KB, 1920x1080, 1446982917339.jpg [View same] [iqdb] [saucenao] [google] [report]
9542858

>>9542544

>Dragon capsule

I don't think so.

>> No.9542859

>>9542544
cool!

can you check on the moon for us?

>> No.9542960

>>9542559
what the fffffff

>> No.9543013

>>9542544
Where's the focken car

>> No.9543064

>>9542544
Fish eye, CGI
REEEEEEEEE!



File: 103 KB, 640x360, Scihub.jpg [View same] [iqdb] [saucenao] [google] [report]
9542529 No.9542529 [Reply] [Original] [archived.moe]

https://mobile.the-scientist.com/article/51851/sci-hub-loses-domains-and-access-to-some-web-services

It's fucking up everything at this point.

39 replies omitted. Click Reply to view.
>> No.9542902

>>9542529
problem is with copyright law, it's absurdly long, should be a few years at the most

>> No.9542908
File: 897 KB, 224x233, 1505430750339.gif [View same] [iqdb] [saucenao] [google] [report]
9542908

>>9542727
>When no scarcity exists

>> No.9543092

>>9542618
Better solution than creating an economy that cannot respond to supply changes: break up the partnerships between universities and journals that allow for journals to charges hundreds of dollars for a complete subscription. ArXiv is free and it does just fine.

>> No.9543094

>>9542727
...Dude.
>>>/his/

>> No.9543154

>>9543092
That's not the problem. All research council / funding body grants and projects are post evaluated using metrics which take into account not only the number of publications, but also the 'quality of the journal', meaning that one publication in a good journal will ALWAYS trump 20 papers that have been put onto Arxiv (which doesn't feature peer-review as far as I know).

The authors themselves wouldn't give a shit about the journals, unfortunately their career depends on publishing in the expensive ones. My last publication fee for an open-access article was around 5000 pounds.



File: 231 KB, 643x537, 1519434676486.png [View same] [iqdb] [saucenao] [google] [report]
9542487 No.9542487 [Reply] [Original] [archived.moe]

>He don't know how to solve it

[math]\int{sec^{3}x tan^{5}x}dx[/math]

9 replies omitted. Click Reply to view.
>> No.9542864

>>9542513
The tans and secs shouldn't be italicized. Use \tan etc.

>> No.9542869

>>9542513
that's a dumb way to solve it

simply use identity of sec^2 then just chain rule

no need to thank me, nerd

>> No.9542882

>>9542487
cant even evaluate that expression

>> No.9542892

>>9542513
You forgot the +C brainlet.

>> No.9543007

>>9542846
or dfrac instead of frac



File: 53 KB, 1200x600, 1491617401408.png [View same] [iqdb] [saucenao] [google] [report]
9542471 No.9542471 [Reply] [Original] [archived.moe]

What, exactly, causes the fundamental forces? Or, why do they exist? Hell, why does anything exist?

>> No.9542476
File: 589 KB, 680x683, Weak fear Strong - Sam Hyde.png [View same] [iqdb] [saucenao] [google] [report]
9542476

>>9542471
the weak should fear the strong

>> No.9542477

>>9542471
If they didn't exist, the universe would stay as a singularity and nothing would happen.



File: 65 KB, 720x405, planet x.jpg [View same] [iqdb] [saucenao] [google] [report]
9542465 No.9542465 [Reply] [Original] [archived.moe]

Any of you fags looking for this? Does it exist or is it just a meme? If you discover it we get to name it. What would you pick?

9 replies omitted. Click Reply to view.
>> No.9542687

>>9542518
I don't think that is really a problem. It just has to have cleared its orbit.

>>9542465
The problem is that we don't really know where to look.
Its proposed orbit doesn't come anywhere near the current bounds of the solar system, so even if it is as big and reflective as Saturn the closest its orbit comes is about 20 times further away from the Sun than Saturn is and the furtherest is about 120 times.
The proposed orbital period is thousands of year and it could be anywhere in that orbit currently. Because its orbital period is so long it wouldn't move very far in the sky over the course of even a year, so even if we capture it on a telescope it would take a long time of observations to notice it moving.

If it is there, likely we will discover it at some point, but what we need is time. My prediction is that people combing through telescope observations will notice a point that has moved slightly over a long period in an unusual direction and that will lead to focused observations that'll reveal it.

The real sad thing, though, is that we will probably never send a probe out to it.

>> No.9542724
File: 4 KB, 113x125, onesyllableoff.jpg [View same] [iqdb] [saucenao] [google] [report]
9542724

>>9542566
Damn, I'm disappointed about this

>> No.9542754

>>9542687
Earth has not cleared its orbit.

>> No.9542818

>>9542754
Well enough. I don't see any competing sized objects still in it.

>> No.9542824
File: 62 KB, 400x400, Praise Kek.jpg [View same] [iqdb] [saucenao] [google] [report]
9542824

>>9542465

Planet Kek

, named after the Egyptian God Kek
, the God of Chaos and Meme Magic

>>9542491



File: 942 KB, 1296x855, 1505044874454.png [View same] [iqdb] [saucenao] [google] [report]
9542440 No.9542440 [Reply] [Original] [archived.moe]

What is the coolest geometrical structure?

>> No.9542442

The point.

>> No.9542452
File: 170 KB, 1200x1153, Icosahedron.png [View same] [iqdb] [saucenao] [google] [report]
9542452

>>9542440
Icosahedron

>> No.9542474

>>9542440
the projective line

>> No.9542479
File: 327 KB, 840x840, 1507011997238.png [View same] [iqdb] [saucenao] [google] [report]
9542479

>>9542440
>>9542442
>>9542452
>>9542474
*yawn*

>> No.9542511

>>9542479
How do you make it without a point?
Huh?
I'm waiting...
No answer?
Well...
It's settled then.



File: 22 KB, 485x443, ijj1aSW.png [View same] [iqdb] [saucenao] [google] [report]
9542439 No.9542439 [DELETED]  [Reply] [Original] [archived.moe]

How do I deal with being a brainlet?

>> No.9542480

tell me

>> No.9542482
File: 128 KB, 1468x867, homemade_3Dquartic_brainlet.png [View same] [iqdb] [saucenao] [google] [report]
9542482

embrace it.

>> No.9542490
File: 7 KB, 229x220, 7588685678.png [View same] [iqdb] [saucenao] [google] [report]
9542490

>>9542439
Make up for being a brainlet by visiting office hours constantly, cheating on exams, buying subscriptions to wolfram alpha and cheg, and my personal favorite, finding a manipulable, introverted smart guy to leech off of and then completely forget about once the semester ends.

Then get into grad school by having excellent grades despite not knowing anything, effectively stealing the spot that could have gone to someone who actually spent the time to struggle and learn the material without relying on rote memorization and likability to pass exams.

>> No.9542503
File: 30 KB, 446x559, 1296358987999.jpg [View same] [iqdb] [saucenao] [google] [report]
9542503

>>9542439
Ignore it. Just like everything bad.



File: 2.32 MB, 3300x2200, 1513440975099.png [View same] [iqdb] [saucenao] [google] [report]
9542404 No.9542404 [Reply] [Original] [archived.moe]

Anyone ever noticed how when a cup of tea has a very thin layer of surface foam, narrow swirly lines (a few mm across) will be cut through the foam at the relatively fast speed of 10-20 cm/s?
I've observed this at temperatures below 80C.

What causes this?

>> No.9542485

>>9542404
Can you post a video of what you mean?



File: 157 KB, 725x1036, sra5p47x8n001.jpg [View same] [iqdb] [saucenao] [google] [report]
9542397 No.9542397 [Reply] [Original] [archived.moe]

If I smashed a bunch of photons together to make a high density shape could I have solid light? I'm trying to build a lightsaber

2 replies omitted. Click Reply to view.
>> No.9542406

it wouldn't be a "light" saber, more of a construct saber, a light saber is a high destiny plasma blade in a controlled saber shape, while you could do this, but it wouldn't be a light saver nor would it cut well.

>> No.9542408

>>9542405
I was using it to say that you could not, as is evidinced by the literal first paragraph, but hey fuck reading links right?

>> No.9542409

>>9542408
He mentioned photonic molecules nowhere in his post.

>> No.9542412

>>9542409
He asked if you could have solid light, photonic molecules are the best you can get.

>> No.9542413

>>9542409
What happens then if you smash photons together?



File: 3.56 MB, 4133x3331, 1518643889329.png [View same] [iqdb] [saucenao] [google] [report]
9542386 No.9542386 [Reply] [Original] [archived.moe]

How do you guys go about self studying a textbook. Is there a goal you set for how much you get done a day? Like a chapter a day etc. How many textboooks/subjects do you take on at once? Im trying to self learn in my free time between classes but i just dont know how to pace myself.

3 replies omitted. Click Reply to view.
>> No.9542703

>>9542512
Autists came together and figured out types can be treated as groupoids, which helps out in proof solving. It's interesting, more of a foundational recent development, not really pivotal for your core classes, but only plebs ignore developments that arent in their fields without at least appreciating the results.

>>9542649
I dont know where you're at schoolwise, but unless you were winning competitions and fratenizing with majors early as a highschool student, the average /sci/fag coming from nowheresville high school and only just learned he wanted to do math should be doing "brainlet" as a freshman/sophomore and the undergrad section as a junior/senior. IMO, the grad section isnt as comprehensive as I'd like, but I'm a bit of a stamp collector. Realize if you can even get through 2-3 of any of the grad books you should probably stick with math as your profession, regardless how overwhelmed you feel

>> No.9542717

>>9542386
Left to right, top to bottom; group words together to make sentences

>> No.9542720

>>9542386
>Learning French just to learn math from a specific non-translated version of a textbook written in French instead of other ones
Is it autism, or is it patrician?

>> No.9542722

>>9542386
I just started and I’m using a calculus textbook that I got for a community college course that I took in high school. It covers limits to multivariable vector calculus over 15 chapters. I’ll usually spend a few days at a time solving every odd-numbered exercise (which the book provides answers for) in every section, completing roughly 2 chapters per month. I do not recommend doing this.

>> No.9542904

>>9542720
That's what normal people do. They learn French, German, Russian, English if it's not their first language, to read books and papers. Only americunts find learning languages to be something weird and think "if it ain't got English translation it ain't worth shit"



File: 6 KB, 225x225, images.jpg [View same] [iqdb] [saucenao] [google] [report]
9542358 No.9542358 [Reply] [Original] [archived.moe]

ball with magnet just in the middle bouncing on an iron surface that the magnet is attracted to..what happens on ground?..what happens in space?

4 replies omitted. Click Reply to view.
>> No.9542381

>>9542373
clearly sobering up

>> No.9542383

>>9542380
not even with magnetic shielding?

>> No.9542400

does gravity do no work aswell?

>> No.9542458

>>9542383
Magnetic fields are created by either moving electric charges (i.e. current) or magnetic dipoles (such as atoms/bar magnets). In the case of current, it takes energy to create a potential which drives current. In the case of magnetic dipoles, the dipoles are formed by other forces which cause positive and negative charges to separate.

>> No.9542475

>>9542400
Work is equal to force times distance, so yes, gravity does work. Magnetic fields don't do work because magnetic fields need to powered by other things, which is what is really doing the work.



File: 66 KB, 525x698, 1518883823855.jpg [View same] [iqdb] [saucenao] [google] [report]
9542350 No.9542350 [Reply] [Original] [archived.moe]

daily reminder issac newton never proved the curve of the earth when theorizing about gravity which is why it is still classified as a theory and not a fact , this is also why like half of modern science is wrong

oh yeah dont forget everything source ever admits that gravity has not been proven
https://ncse.com/library-resource/gravity-its-only-theory

>> No.9542376

>>9542350
>This satirical look at "only a theory" disclaimers imagines what might happen if advocates applied the same logic to the theory of gravitation that they do to the theory of evolution.
>satirical
Germ theory is also only a theory.

>> No.9542382

>>9542376
no

>> No.9542393

>>9542382
>people are so bad at picking up satire it outright states it is satire so people will know
>"[Gravity] utterly fails to account for obesity."
I honestly hope you people don't use this page as an argument against gravity being real.

>> No.9542394

>>9542393
kek

>> No.9542398

>>9542393
the weight of all the oxygen,carbon, nitrogen and other atoms in the air keep things down this is why gas giants like Jupiter and Neptune have more "gravity" than earth even though rocks are way denser than gas, gravity is a lie



File: 151 KB, 640x640, file.png [View same] [iqdb] [saucenao] [google] [report]
9542311 No.9542311 [Reply] [Original] [archived.moe]

If a person were to transfer their mind to a child's body, and they were emotionally, psychologically, and sexually mature as an adult but in the body of a child, even saying reverting back to their own child body, would it be considered "child molestation" if the person is technically "9" to do any type of sexual activities with another 9 year old or what it be considered experimentational?

Yes I just made that word up

>> No.9542314

>>9542311
cf. Williams "The Self and the Future"

>> /his



File: 25 KB, 1202x406, What-is-Python.png [View same] [iqdb] [saucenao] [google] [report]
9542300 No.9542300 [Reply] [Original] [archived.moe]

I desperately need help. I have found myself in a Comp Sci program but I am pretty retarded at it. We are using Python. The following is the assignment I am working on

> Implement a small library of 3 books using a Python dictionary.
> Implement a Python function to print details about all books in the library.
> Implement a Python function that adds a book to the library.

>Your function should ask for the book ISBN, title, author and how many copies have been purchased. The function should update the library inventory (the dictionary) to include the new book.
>If the book is already in the library the system should update the quantity.
>Implement a Python function that checks out a book for loaning.
>Implement a Python function that searches the library for a book by the book title and returns the book’s ISBN

Please help

4 replies omitted. Click Reply to view.
>> No.9542332

>>9542321
>https://docs.python.org/2/tutorial/datastructures.html#dictionaries

Thank you kind anon.

>> No.9542347

>>9542300
Please be bait

>> No.9542384

>>9542300
https://pastebin.com/L0dj6fLE

Took all of 5 minutes to write.

>> No.9542389
File: 9 KB, 150x217, SICP_cover.jpg [View same] [iqdb] [saucenao] [google] [report]
9542389

Drop out of college, because this is the only CS book you will ever need.

>> No.9542390
File: 89 KB, 603x324, bjaaarne.jpg [View same] [iqdb] [saucenao] [google] [report]
9542390

>>9542384
>assignment in Python
>does it in a superior language
You sound like a pretty cool guy.



File: 30 KB, 696x392, aHR0cDovL3d3dy5saXZlc2NpZW5jZS5jb20vaW1hZ2VzL2kvMDAwLzAzOS84NDcvb3JpZ2luYWwvc2h1dHRlcnN0b2NrXzEwMTAwMDcwNy5qcGc=.jpg [View same] [iqdb] [saucenao] [google] [report]
9542298 No.9542298 [DELETED]  [Reply] [Original] [archived.moe]

https://join.discordservers.com/317165289769009152

Flat Earth Discord

>> No.9542387

>>9542298
Unironically accurate as Flat Earthers can't agree on anything aside from the Earth not being a globe.



File: 79 KB, 1837x2560, 1837px-Quaternion_2.svg.png [View same] [iqdb] [saucenao] [google] [report]
9542268 No.9542268 [Reply] [Original] [archived.moe]

>yfw there is an entire branch of mathematics dedicated to "analysing" completely made-up numbers that have literally no physical representation in the real world
Friendly reminder that if you still take imaginary numbers seriously in 2018 you are a hopeless brainlet.

And before retards start coming in to debate this, please tell me how to get this this mythical realm of yours where one can possess 7 + 9i apples.

45 replies omitted. Click Reply to view.
>> No.9543010

>>9543000
I don't know, what is it?

>> No.9543021

If you want to find 3th degree polynomial roots then you're forced to use imaginary numbers even if you polynomial or your roots don't contain an imaginary term

>> No.9543039

>>9543010
For a sec I thought you meant radicals (nth roots). Algebraic numbers can't always be represented by these

Algebraics are still a proper subset of the reals

>> No.9543110

>>9542268
>literally no physical representation in the real world
not true

>> No.9543140
File: 25 KB, 433x380, 1470524378158.jpg [View same] [iqdb] [saucenao] [google] [report]
9543140

>>9542268
They work perfectly well in our system of mathematics and have led to discoveries applicable in the real world despite not being "real" themselves. What's the problem?



View post