/sci/ - Science & Math

>>4753770
>that feel when all of this applies to me except I am somehow not depressed

We, as a collective, could mark threads which are clearly not directly /sci/ related.

like with a certain one word post - and then if you read the word a couple of times it's clear that the thread is considered cancerous. One can then easily identify them and the /sci/ interested core might get rid of them that way.

>>4359535
>mfw

>>4305894
>mfw

>that feel when dead wife

Fexofenadine

4-[1-Hydroxy-4-[4-(hydroxydiphenylmethyl)-1-piperidinyl]butyl]-α,α-dimethylbenzeneacetic Acid Hydrochloride

BEcause I have majig powers

>that feel when just 5 minutes ago did I officially finish my final piece of work for the quarter
>that feel when I get a 3 week break and then it's back to cramming

"I don't know" is the smartest thing you can say as an agnostic.

I'm looking for a good Quantum Mechanics book. Everything B&N has is all bullshit pop physics and the For Dummies book written by a terrible author. I've got Feynman's Path Integral formulation, but I want the "classical" version of QM. Recommend tutorial books (preferred) or textbooks.

This is a good year for science indeed. Also keeps me more motivated to continue to study. ;)

If what the experiment is shown the be true, then this also unlocks possible solutions to black hole theories, because much of the currant models of physics brake down when matter falls past the event horizon (because it would be moving FTL).

This is probably just as important time in scientific history as when humans found out that earth is not in the center of the universe. New laws of nature will be discovered. It also stimulates the imagination that maybe one day we will be able to transfer information faster than the speed of light...which is useful for interstellar travel.

>>3712481
To answer your questions actually make sense only in the reverse oder:
>would it be ok to call the new variables "natural" or does natural imply that U must start as U(S,V)?
There is no choice but U(S,V), since
P=-∂U/∂V resp. P=-T(∂S/∂V)
and
T=(∂U/∂S)^{-1} (I set k always 1 here, for simplicity)
are both derived variables.
Notice that the U(T,V) only worked because back then, T was experimentally defined via PV=NT.
From a technical POV there is no temperature before the entropy S, which can be understood best in the context of statistical mechanics. So U(S,V) is the way to go because S=S(U,V,N) is just a computable number and V is a parameter which is obvious from experiment, unlike P and T which are rather abstract, although both can by motivated quite well.

>But if your process has U as a function of other variables, then you'd get a different dA.
You get A(T,V) only from U(S,V). The helmholz free energy A is a quantity defined via Legendre transform of U(S,V) with respect to S.
http://en.wikipedia.org/wiki/Legendre_transform#Thermodynamics
This tranformation is a way on NOT losing the information you would when only setting U(T,V):=U(T(S,V),V).
You have dQ=TdS, a heat flow and if heat flows than the energy U changes, since dU=dQ-dW (or +dW in your convention). The very purpose of defining A is to construct an object which is _free_ from heat variations, so you define A in such a way that
dA=d(U-TS)=dU-SdT-TdS=dQ-PdV-SdT-dQ=-PdV-SdT
The very thing you wanted to achieve is get rid of dQ in dA and that's what happened.

Looking for Floyd Principles of Electric Circuits 9th.

All this sit down chair episodes. What are the titles name. Thanks.

>>3631924

So guys, this one's a pretty difficult one to look up on the google precisely:

Whats the difference between a derivation and proof?