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Archived threads in /sci/ - Science & Math - 29. page
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File: universe expansion.jpg (64 KB, 608x514) Image search: [iqdb] [SauceNao] [Google]
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How is it that a photon which is emitted from an object with a recession velocity greater than c can reach us at all? I understand that at first the photon is indeed receding but how can it ever reach a coordinate point where the recession velocity is less than c if it started out in one that was greater than c? Shouldn't the nature of accelerated expansion imply that it will only ever recede because distance is being "created" faster than light can traverse that distance?
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>>7812389
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>>7812389

The photon cannot travel faster than the spacetime expansion, this is the postulated fate of the future universe where the sky beyond locality is completely dark.
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>>7813685
Actually its hyper refractive

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So Darwinists, if evolution is true, why is it still a theory?
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because proving science is hard
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In science, the word "theory" means something different than what the public thinks it means. The public thinks a theory is a hypothesis. In science, it means it's an idea that has not yet been disproven. This is as close to calling it "true" as science will ever come. Science calls nothing "true" as a matter of principle- it must be assumed that anything can be disproven.

Gravity, for example, is still a theory.
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>>7812394
You filthy atheists with your theories of satanic gravitation.

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Why did some native americans survive the epidemics?

It wiped out so many yet some walked away. I feel it's different than Europe because the Americas were isolated and much less exposed throughout their history
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>>7812350
>I feel

Dropped. Feelings are discussed on tumblr.
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>>7812351
Fuck off
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>>7812356
No, for real. Nobody gives a fuck about what you feel. What argument do you have for it not being simply that some of them were immune or were not exposed?

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/sci/ Let's solve simple mathematics problems using triple integrals.

Here's the first one.

>Don't forget to use your conversions senpai
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>>7812302
>mi
>ft
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100 mi^2 * 20 ft * 0.4 micrograms / mL

== 632000 kg

File: sdfdsf.jpg (40 KB, 350x700) Image search: [iqdb] [SauceNao] [Google]
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Im bored, what are some good textbooks to read for fun?
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NEEEERD
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>>7812266
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>>7812278
Please ur on /sci, go fuck urself

Hi /sci/,

I'm trying to find the proper categorical analysis tool to test the independence two contingency tables (which you could see as a 3D contingency table I guess).

I have the following table:

CatA1,CatA2,CatA3
40,190,50
200,150,50
90,110,20

(See next post for how I'm visualizing it)

Now, this table is from some point in time.
At another point in time, I have a similar table with different data.

What I'm trying to figure out is how to test for independence of the two tables.

If I just wanted to test the table in itself, the answer would of course be to do a $\chi^2$-test, but I don't think that's valid here.

Could you help me out?
Pic related, it's the book I'm using.
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File: example.png (6 KB, 672x672) Image search: [iqdb] [SauceNao] [Google]
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This is the format I'm using to interpret the data at one point in time.
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I'm not too sure but my first intuition would be this

http://sphweb.bumc.bu.edu/otlt/MPH-Modules/BS/BS704-EP713_Confounding-EM/BS704-EP713_Confounding-EM7.html

I would need to read up. I have that text book available so a page or reference would help me.
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>>7812297
Thanks, I'll give this a read through.

It's not actually something from the book, but my supervisor gave me this one to read because he thought it might contain something for it.

File: 1452886610498.jpg (193 KB, 647x898) Image search: [iqdb] [SauceNao] [Google]
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Hey guys I dont understand a concept, and would like help finding out what its called so i can look it up on Khan Academy or wherever.

Basically its simultaneous equations in 3D. You get 3 equations involving x, y and z, and from them you have to declare if there are no points of intersection, infinitely many, or one unique point.

Basic I know - does anybody know what words I can use to look this up? I cant find it on Khan Academy anywhere.

>pic unrelated
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It is called love.
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>>7812181
are the equations linear in x,y,z?
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System of linear equations? Linear algebra

File: 1451100387694.jpg (120 KB, 720x960) Image search: [iqdb] [SauceNao] [Google]
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Why haven't our feet evolve to face the elements?
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>>7812166
They have. Stop wearing shoes for a few years and your feet will build up the massive callus that they're supposed to have. The only reason that shoes are so necessary is because it's not the elements we need protection from, it's all this broken glass and shit just lying around from people being assholes.
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>>7812166
Your feet will adapt to your environment. There are people in Africa and South America that go their entire lives without wearing shoes.

But if you grow up in a civilized nation, chances are you'll have pussyfeet because you'll have been wrapping them in cotton and rubber since you were born.
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>>7812166
>post a nice piece of tail
>guaranteed replies

File: CodeCogsEqn.gif (650 B, 188x20) Image search: [iqdb] [SauceNao] [Google]
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Is this even possible?
$\sqrt{6} = \sqrt{9-3} = 3+i\sqrt{3}$
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Are you implying that $\sqrt{x}+\sqrt{y}=\sqrt{x+y}$?
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>>7812176
wait why doesn't the latex work
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>>7812162
No, you can't break up sums in a radical.

For example, $16=\sqrt{256}=\sqrt{64+64+64+64} \neq \sqrt{64}+\sqrt{64}+\sqrt{64}+\sqrt{64}=8*4=32$

File: ring_markings_planet.jpg (1 MB, 1600x1200) Image search: [iqdb] [SauceNao] [Google]
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How would Earth be different if it had rings?

How should those rings be if we want to avoid a constant meteorite rain?
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File: 1385490383617.gif (2 MB, 300x169) Image search: [iqdb] [SauceNao] [Google]
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>>7812076
You mean instead of a moon? Well, the tides for one.
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If the Earth had rings. They'd merge into a moon.

Albeit a smaller moon than the one we have.
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I guess they would have advanced our spacefaring capabilities, lots of rocks to investigate/claim.

File: 1448862429192.jpg (50 KB, 736x642) Image search: [iqdb] [SauceNao] [Google]
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Is it true that chemistry degrees only get you employed as a high school level teacher?
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Yes dude ggwp
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>>7812067
Is it true that a ____ degree will only get you a subjectively bad job?

Wut r u dum
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>>7812082
Every time it was brought up I'm told it's suddenly useless and unemployable.

File: Phi_ourier.png (1 MB, 2560x1440) Image search: [iqdb] [SauceNao] [Google]
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Where did the phase go from the first to the second formula?
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>>7812056
It was expanded into a sine and a cosine.

The purpose of the fourier series is that you can simplify it to a series of coefficients. If you have to keep track of phase as well, well then you have to keep track of more things.

The first formula and the second formula are equivalent at corresponding A_n, a_n, b_n, and phi_n. In case you didn't know, sin(x+pi/2) = cos(x)
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>>7812092
I should clarify: generally you look at just the fourier series when you don't particularly care about the phase. If you also care about the phase, you'd more likely use the fourier transform. Some math majors might get angry at me for this explanation, but as a EE that's how I like to think about it.
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>>7812092
>>7812099
Thank you.
Does the Fourier transform of a periodic function change if I change the phase of the function ("move it sideways")?

File: image.jpg (97 KB, 1000x733) Image search: [iqdb] [SauceNao] [Google]
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So we have yet to come in to contact with aliens. I do believe they exist.( virtually impossible for them not to) but what if they don't exist... Yet. There has to be a first everything. What if it is us?
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>>7812048
What if we're the aliens? Why don't you go fuck yourself.
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>>7812052
Well we are technically aliens to life forms not from earth.
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>>7812052
He's saying what if we are the first intelligent life to form and there's have yet to form.

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What if the darkness the shadows create in the absence of light is the dark matter/energy we are looking for? Would it be possible to measure the force these shadows create?
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>>7812023
Thats the thing, the shadows are just the abscence of light where the energy is on our body leaving the shade on the ground. Based on heat alone im willing to say their is less energy in the shadows
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Childish inane garbage threads like these belong to trash

>>>/trash/

>>>/trash/

>>>/trash/

>>>/trash/

>>>/trash/

File: binary.jpg (562 KB, 680x440) Image search: [iqdb] [SauceNao] [Google]
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If I play chess against a computer it is able to pick out the best moves against me and deduce the likely actions I take.

Given that chess programs can beat even the most accomplished human chess players, do these programs display human levels (not limited to) of reasoning? They are certainly capable of reasoning that can consistently beat human opponents.

I am curious at the progress of artificial intelligence, given that reasoning is a logical process and for the most part as humans we learn through reasoning, making deductions from patterns.

We know that...
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>>7811969
>They are certainly capable of reasoning that can consistently beat human opponents.
no

>I am curious at the progress of artificial intelligence
You aren't, or you would be reading journals on it or an introductory book like bishop

>We know that Chess programs can adapt themselves and essentially learn from their mistakes.
Genetic algorithms are especially bad at chess

>What...
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File: AI.png (262 KB, 697x534) Image search: [iqdb] [SauceNao] [Google]
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>>7811969
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>>7811972
Not the retarded op . Bishop book ? Elaborate and would that be after norvig . Also what mathematical background would be preferable

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