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16:00
On the other hand, within its domain the standard model seems to describe everything we see.
The problem is that we can't seem to find the boundary of that domain experimentally.
@LeakyNun -b/a = (b^2-2ac)/a^2 ?
It's also worth emphasizing that the Higgs was something people expected to see (though people didn't know what version it would take).
@Abcd I'll keep asking "why" if you don't care to explain.
Zee
Zee
You can only build a theory on proofs or experiments , you can't keep making guesses to build a theory and then call it a theory without any evidence
Eh, you can. You just have to be entirely honest about that.
16:02
Guys, is this also an “affirming the consequent” case? Because I see that if $V_{ij}$ is a function of only the distance between the particles, then we have that $F_{ji}=-F_{ij}$ and apparently the forces line along the line going the two particles. But did it also go in the other direction?
@LeakyNun First please tell whether its corrrect
It's also worth emphasizing that the level of 'proof' in theoretical physics is different than in math.
I am aware of that
actually, that was in regards to my other conversation :)
But it dovetails nicely, heh
@Abcd (1/α^2) + (1/β^2) = (α^2 + β^2)/(α^2 β^2) = ((-b/a)^2 - 2c/a)/(c/a)^2 = (b^2-2ac)/c^2
16:04
hahaha, oh oops:P
But that's more or less what the author is ranting about
Zee
Zee
@Semiclassical that's why you need experiments, otherwise physics is just bad math
verrrry bad math:'(
Eh. I think that's too harsh a tack. You can do theory in the absence of experiment, just based on physical principles. But you have to be very very very careful about what you're doing, and especially you have to be honest about that you're doing is high-risk.
lol, careful in physics? I feel like I lose my entire sanity the moment I open a physics book:P
16:05
@Semi aren't you just kind of doing math then
(if you're being very very careful)
Zee
Zee
@Semiclassical these principles are the result of experiments...
This is getting a tad too much into the philosophy of science for my taste.
@Eric Perhaps. But the questions one asks in math versus physics also tend to be a bit different.
Zee
Zee
@Semiclassical it's pretty unphilosophical if you ask me but fine
"Principles are a result of experiments" is most definitely a philosophical claim.
Zee
Zee
Give me a principle that isn't so?
16:08
(1/$α^2$) + (1/β^2) = ($α^2$ + $β^2$)/($α^2$ $β^2$) = ((-b/a)^2 - 2c/a)/(c/a)^2 = (b^2-2ac)/$c^2$
@LeakyNun Please write this using proper symbols, I cant understand aught
sorry
Special relativity, for one.
I guess that's kind of true depending on what you're doing. Like if you're doing Riemannian geometry a lot of what you are doing is pretty physical, fundamentally a lot of results boil down to "given second order behavior of metric, derive properties of space" which kind of feels like what you do in mechanics a lot of the time. @Semi But idk much about physics
It required evidence to convince the physics community that it was correct, to be sure.
@LeakyNun are you typing?
16:09
@Zee even if that's a strong philosophical thesis it's still a philosophical thesis.
But Einstein's motivation was based on thinking about space and time, not from specific experimental results.
Even more so with general relativity.
Zee
Zee
Well special relativity is kinda within the realm of math, hence being invented by poincare
Poincare having anticipated special relativity != inventing relativity.
$$\begin{array}{rcl}
\left(\dfrac1\alpha\right)^2 + \left(\dfrac1\beta\right)^2
&=& \dfrac{\alpha^2+\beta^2}{\alpha^2\beta^2} \\
&=& \dfrac{\alpha^2+2\alpha\beta+\beta^2-2\alpha\beta}{(\alpha\beta)^2} \\
&=& \dfrac{(\alpha+\beta)^2-2\alpha\beta}{(\alpha\beta)^2} \\
&=& \dfrac{(-b/a)^2-2(c/a)}{(c/a)^2} \\
&=& \dfrac{b^2-2ac}{c^2} \\
\end{array}$$
@Abcd ^
Oh. Thanks. This is much better
Zee
Zee
16:11
Well he gave the mathematics of it even if the interpretation was wrong
Of course, Einstein is also taken up as an example of physical reasoning gone wrong, e.g. his search for a unified field theory.
Zee
Zee
Anyway now am just arguing for the sake of arguing so let's finish this semi
Quite.
Instead, here's a fun physics question.
Suppose you pass a sphere at a very high speed (not too far from the speed of light).
@LeakyNun is this not equal to -b/a
What shape would you perceive?
Zee
Zee
16:14
Mmmmmm a line?
That's what most people who've seen SR would say.
But, actually, that's not true. You'd still see a sphere.
There'd be spherical aberration, but the outline is still spherical.
@Abcd yes that is
@LeakyNun So that's exactly what I had said.
Zee
Zee
Was that experimentally verified? Lol
@Abcd oops, I'm blind
16:15
It's just a consequence of SR.
@LeakyNun Sarcastic?
It's called the Penrose-Terrell rotation/effect.
@LeakyNun Sorry. I had written the right thing in my notebook but copied it wrongly
@LeakyNun What to do next?
This video includes some visualizations of relativity, and it includes the rotation effect (though not as clearly as the rest, tbh): youtube.com/watch?v=JQnHTKZBTI4
$$\begin{array}{rcl}
-\dfrac ba &=& \dfrac{b^2-2ac}{c^2} \\
bc^2 &=& -ab^2+2a^2c \\
ab^2 + bc^2 - 2a^2c &=& 0 \\
\dfrac bc + \dfrac ca - \dfrac{2a}b &=& 0 \\
\end{array}$$
Hence it is D
@Abcd ^
16:18
@LeakyNun I didnt understand
Zee
Zee
@Semiclassical interesting... let me ask you this since your knownphysics
@Abcd which step?
I think there should be some trick in this question.I also placed a bounty some time back but no answer.math.stackexchange.com/questions/2138963/…
@LeakyNun last step
divide both sides by $abc$
16:18
If sum is zero, does it mean they are in AP?
@Abcd yes
if $x$, $y$, $z$ are in AP, then $x+z=2y$, or $x+z-2y=0$
Zee
Zee
@Semiclassical can we formulate fake laws of physics and try to derive interesting results from that?
@LeakyNun How can you be so sure?
@Abcd AP means that $x-y=y-z$
add $y+z$ to both sides to get $x+z=2y$
@LeakyNun oh
16:19
Well, depends on what one means by that.
@LeakyNun I don't know these formulae :(
One can certainly invent a lot of different models, none of which may be really correct.
@Abcd which step do you not understand?
But I'm not sure I'd consider that as 'fake physics.'
@LeakyNun I understood the steps but I didnt know these formulae that you used for AP
16:21
so do you know now?
if $x$, $y$, $z$ are in GP, then $xz=y^2$
Zee
Zee
@Semiclassical for example , i can set up different newton laws, by changing the formulas or by saying "for every action there is an opposing but UNequal reaction"
Kinda like imaginary physics
Well, the example in that case would amount to considering negative masses.
@LeakyNun Please repost the formulae. Also, should I know the derivation of Vieta's formula?
@Abcd yes, you should
You'd still have momentum conservation in that case.
16:23
@LeakyNun Should I know the derivation of all formulae I learn?
@Abcd depends on what formula it is, but I would encourage you to learn the derivations
Moreover, Newton's third law as stated like that is not universally valid.
The Lorentz force law being the most obvious case.
@LeakyNun okay thanks. I am re-seeing your solution now
@Abcd e.g. I wouldn't tell you to learn the derivation of, you know, $F=lIB$
On the other hand, the underlying principle of momentum conservation does still hold (if you include the momentum contained in the electromagnetic field)
Zee
Zee
16:24
ao we can build physical models on non sense assumptions like negative mass?
@LeakyNun I hate physics. I won't learn any derivations there :(
You can build models, sure. Whether someone would call them 'physical' is a different matter.
Typically a physicist would call such a model "non-physical" because it doesn't behave in a reasonable way.
Zee
Zee
@Semiclassical isn't that fascinating? Non physical physics?
(Within the realm of classical mechanics, anyways. Within the realm of quantum mechanics there is a notion of 'negative mass' but the name is largely historical. See this blog post for some critical remarks on a hyped 'discovery of negative mass.')
@Abcd so do you know the derivation of the Vieta's formulae?
I can prove it to you here
16:27
Eh, depends.
@LeakyNun Prove it if you wish.
Sometimes a model which you know to be wrong can still be useful.
@Abcd do you wish?
For instance, if I say that a rod is rigid, strictly speaking I'm talking nonsense
@Eric Weird, I wasn't on
Zee
Zee
16:28
@Semiclassical yes , but it's good enough , but what if we push the boundary? Treat things in a very opposite way
If a rod is perfectly rigid, it would have to respond instantaneously on one end to being tapped on the other. But that'd allow for faster-than-light signaling.
Anyway, how goes it?
In truth, any rod has some elasticity, so tapping it would lead to a longitudinal wave pulse which travels slower than the speed of light.
Zee
Zee
Anyway @Semiclassical it was good talking to you
But if I'm just doing a lab demonstration then this is all very silly to worry about.
Zee
Zee
16:30
Yes the space between the atoms
The wave speed is slower than the speed of light, but it's far faster than I can perceive.
So I might as well just say that it's a rigid rod in that case. I know the model isn't physically absolutely correct, but it doesn't have to be to be useful and relevant.
It can be interesting to push that in the far other direction, to be sure: To think of ways that modern physics could be wrong, and try to figure out whether that could be observable.
It's not my own cup of tea, though.
Zee
Zee
Yes yes , you like to tame QM
Something like that.
Zee
Zee
Anyway my man , good talk , bye
16:38
@LeakyNun Just minute. Let me google first
@LeakyNun I can't find it's proof. You may prove.
@Abcd let $\alpha$ and $\beta$ be the roots of $ax^2+bx+c=0$
by the argument we have gone through today, $ax^2+bx+c = a(x-\alpha)(x-\beta)$
@Daminark that's strange you popped up as if you had entered
@Abcd ok?
Yes
Yes
@LeakyNun Why is there an a in RHS
Can $[a,b]$ reasonably be interpreted as, say, an interval in $\mathbb{R}^3$? Or did my professor somewhat bully me? (I use the word "bully" because there were instances of assured bad behaviour from her)
16:41
@Abcd to match the leading coefficient
@LeakyNun Okay.
yes
@VincenzoOliva It really can't. [a,b] is in R^1, full stop.
@Abcd can you expand the right hand side?
@LeakyNun yes
You could use $[a,b]$ to represent the line segment connecting two points $a,b$ but that's not standard notation and you would be expected to make that convention clear.
(especially since one has $\overline{ab}$ as defined notation for such a segment already)
16:44
@Abcd are you typing?
No
Okay, let me calculate
can you expand the right hand side?
yes
Expanding...
@Semiclassical Right? You ought to write e.g. $[a,b]\times\{0\}$ if you're saying you're in $\mathbb{R}^2$, no?
@LeakyNun ax^2 -abeta x - a alpha x + a alpha beta
16:46
yes
Assuming that you want to do the segment along the x-axis, sure.
so we have $ax^2+bx+c = ax^2 + (-a\alpha-a\beta)x + a\alpha\beta$
Can you compare the coefficients?
JAM
you like bread with jam?
Mh-mh. Gosh, she was so imbecile
16:48
Now, if they've defined somewhere that [a,b] is intended as a line segment with a,b being points in R^2, then I can understand.
Yeah, however she said that to despise me not defining that as interval in R
coo
Well, I'd more object to not saying that a,b are real numbers.
It doesn't make much sense otherwise, to be sure, but it's a good practice to be in.
@LeakyNun I meant Just a Minute
Even if [a,b] is written to be the domain of a function?
16:51
@LeakyNun yes
@LeakyNun b = -alpha a - alpha beta
I think it's still worth saying, e.g. $f:[a,b]\to \mathbb{R}$ for some real $a,b$.
@Abcd the second term on the RHS
But as far as I know the usual definition of interval is for real values.
@LeakyNun I didnt get you
it should be "a beta" not "alpha beta"
16:53
Just a second. I am seeing the steps again.
@Semiclassical Yeah. By the way, she would even object to writing "for some/every blabla" right after some definition. Isn't that a stupid observation? I've seen actual papers written like that
@Eric shrugs in LaTeX
:/
I can understand that in a -very- specific context.
@LeakyNun -> b = x(-a alpha - a beta)
there shouldn't be an x there
16:56
Namely: "For the purpose of us learning how to write proofs, I'll expect you to always report definitions in the following way." But that only works if that's been made explicit.
@LeakyNun I got the proof for the sum :)
I understood , I mean
Otherwise I consider that to be shifting the goal posts.
@LeakyNun What about Product?
@Abcd compare the constant term
There's a judgment call, of course, as to what proofs are 'reasonably clear.' It could be different in a paper than in a book, for instance.
16:58
@LeakyNun Product is -c/a. AM I right?
Wow. Thanks a ton :)
But for the purpose of teaching the expectations should be made reasonably explicit. @VincenzoOliva
Hey @Mike!
@Semiclassical Pretty much :/ And I don't recall any "diktat" of that kind, so yeah, let's move on
17:01
Are you home?
I guess it's better to write things in that manner just to prevent such situations
@Abcd wait no
the product is c/a
@LeakyNun Yes. Corrected my error.
17:36
hello ... anyone here?
Hello!
Hello Fargle
I was wondering if I could ask elementary question about algebra
in integral domain, suppose $d$ divides $a$, how do we represent it?
@SantoshLinkha $d | a$, or $a = kd$ for $k \in R$ (where $R$ is the domain in question).
(whoops)
17:39
my original question is like this
Let $a, b, c, d$ belong to domain $R$ and satisfy $a + b = c$. Assume $d$ divides two of the elements $a, b, c$; prove that $d$ divides the third.
so if I assume $d \mid a$, may I write it as $a = kd$ for some $k \in R$?
Absolutely.
thanks :) is there any condition for $k$ like ... it cannot be unity or units?
eh, a divides itself.
so you can certainly write a=ea in that case.
@SantoshLinkha If $k$ is a unit, then both $a | d$ and $d | a$ (why?), and they're called associates
$ks = 1$ for some $s \in R$, if we multiply both sides by $s$, then we get the result :D
thanks @Fargle
17:45
Yup yup!
what's all that from? real analysis?
number theory?
@JoaquinBrandan Abstract algebra, specifically ring theory.
algebra ...
anyway guys, thank you ... if I have questions,, Iwill let you know :D
Of course @Santosh
Hi @Fargle
17:48
Heya @Ted!
Long time no see.
Been busy preparing for finals and doing birthday things.
Oh, happy belated birthday! How does it feel to be 18? :D
I hope you do well on your finals.
17:51
Oh, they're all done. I felt proud of my work on my real analysis and complex analysis finals.
Good man! Glad you're on a good road now.
Hah, me too. Maybe I'll retain some of this knowledge for next semester too--my school's offering a class on Lebesgue integration.
Cool.
OK, I have to go back to the kitchen. Back later.
anyone knows if this definition of a complemented lattice is valid?
https://proofwiki.org/wiki/Definition:Complement_(Lattice_Theory)

I mean, if it's true then any bounded lattice $L$ is a complemented lattice since $\forall x \in L: x \lor \top = \top$ and $\forall x \in L: x \land \bot = \bot$ so the bounds are the complements for all elements in the lattice, so all bounded lattices would be complemented lattices.
Hallo once again
18:03
hi!
How goes it?
great, thanks ^^
working my way through a set theory book
Sounds fun
Hey @Liad and @Akiva!
@Daminark Hi ! how are you?
Aight, you?
not bad :P
We created a D&D alignment chart for a bunch of our professors and it's glorious
Hm. Dr. Sclar (my history teacher)… lawful evil, maybe?
As a student, I'm very much CN.
I'd like to think I'm NG.
18:11
My English teacher might be CG
I have no idea what I am.
Maybe I haven't played D&D enough. (Note: I've never played D&D)
I'm probably chaotic
I'd like to think I'm CG, probably with some element of CN
In normal life, I'd call myself either CG or NG.
Nobody ever wants to call themselves evil, probably
But as a student, I'm wildly independent to the point of only ephemeral attendance, and tend not to involve myself in group projects when I can help it
Is that what chaotic means?
Then I'm probably chaotic. Or lonely. One of the two.
18:14
Chaotic implies a tacit disrespect for the rules and norms in place
Hm. Then I have no idea what I am.
and/or a total lack of desire to conform to said rules and norms
I'll say CN, probably.
I'd put myself at NG because I tend to act entirely outside my self-interest, and though I respect rules and norms, I see them as mutable and subject to personal interpretation, and in some cases may be safely ignored
I tend to go with rules, not norms
18:18
I respect principles of organization but am skeptical of institutions.
People often call Meyers-Briggs "horoscopes for pseudointellectuals." I wonder what that makes the D&D alignments.
Though the nine alignments thing doesn't pretend to be serious.
I think there's something to MBTI but it shouldn't be used as a be-all end-all.
There should be Halloween-themed horrorscopes somewhere
Every test I've taken has identified me as INFP, but going the extra step and asking "Well, what should my career be?" seems a bit fallacious.
What do they stand for, again?
Introvert something
18:23
Introverted, iNtuitive, Feeling, Perceptive
as opposed to Extraverted, Sensing, Thinking, Judging
The issue I see most people have with MBTI is taking those letters at literal face value rather than looking at what the letters say about your supposed Jungian archetypes.
It's sorta like the zodiac. (Or the four medieval humors.) As a summary of some common personality types, it's interesting.
But take it seriously and you're pretty much a dope.
I find that the Jungian archetypes do to some extent describe my modes of interaction well, but that's not to say it's perfect, and it's also not to say that it's not a case of self-identification bias.
Let F be a field. What does one call the structure one get when one writes F^p
For example what is Q^5 where Q is the rational numbers?
It may it depend on context, but what springs to mind is just the p-fold Cartesian product i.e. ordered p-tuples in F.
I'm trying to understand this theorem
18:36
In that case my guess would be that it's the subset of F consisting of all elements that are p-th powers.
So X^n a is irreducible iff a isn't a p-th power for any p dividing n.
yeah that makes sense
thanks
18:52
tfw you're still getting rep from a two-and-a-half-year-old answer
I have an answer on the differentiability of |x| at x=0 from 2014 that I most recently got rep from today.
Mine was for a soft question on applicability of diff eq techniques.
19:10
Guys ,I am really sorry but I have to post a damn chemistry question over here due to the non working of "The periodic table" ,tell me what is the answer for this following question :)
Qn no.5
more specifically, you've got an organic chemistry question. (aka a part of chemistry I have absolutely no knowledge of.)
I am thinking the options given are wierd; Let others think them@Semiclassical
The answer I was expecting is not there. So...
but it's gotta be (a), right? There are 8 carbons in the main chain and I think (b) is not even grammatical.
oh, no it's probably (b)
when I asked loong he said a) and now the answer given is a)
I am just stuck in this simple low grade question;
The real question is, does IUPAC assume that the -al suffix applies to the first carbon if not otherwise specified
If the answer is yes, it is (a). If the answer is no, it is (b).
This is my analysis :P
19:20
Oh I see ;now I got it if you start from the left side you get a) correct but if you start from right then b) seems correct
So which has more priority aldehyde or alkene ,by left brain says the former should be correct;)
by--my
[in SE chat you can edit your own messages for a couple minutes.]
19:41
@ShaVuklia Oh, I see. Then I hope you'll have fun with physics. :-)
20:01
@satyatech It's 3,7- dimethyl octa - 2 - dienal
@EricStucky The answer is surely a
@satyatech Aldehyde has more priority
@satyatech remember: Functional group > Double Bond> Tripe Bond
@satyatech Are you preparing for JEE advanced - 2019 or 2018 or 2017?
20:49
hello anyone here?
Hi, can someone solve this problem for me? math.stackexchange.com/questions/2263365/…
@Santosh what's your question?
algebra related
go for it. I'll see what I can do
it's more of an assignment ... I few yes/no answer and hint for it
*I need final yes/no answer ... and few hints on how to arrive at it.
Anonymous
@satyatech Answer is (a).
20:54
@San
yes please
@SantoshLinkha hint for (a): check first its' a ring, that it contains R, and that it contains \alpha_i's.
Smallest means that you can't remove any element from S.
HTH
*any element from R[\alpha_i's]
umm ... is it smallest? there was theorem related to it, but I did not copy it during lecture
and thanks :)
smallest means every other ring that sastisfy your conditions must contain it
*satisfy
it's equivalent to checking you can't remove any element
hmm .... i will try it :D
21:04
Good luck!
thanks :)
@JohnJiang is $\alpha_1, \dots ,\alpha_n$ linearly independent?
@SantoshLinkha not necessarily?
what happens if \alpha_i are all equal to a single \alpha
?
umm .... we get extension of degree two?
if $\alpha$ is not algebraic over $R$?
21:25
are we still looking at (a)?
yep ... I am browsing through my notes though you told me to check weather you can remove any element from R
it's like brute force hack ...:S
seeing if it can be done any other way
it's not that I don't like your method, I am just trying to remember if there is any theorem for it ... i forgot it during my lectures
how come $A = \{ \alpha_1, \dots, \alpha_n \} $ be a ring/field?
I don't understand your last question
checking "any" element is pretty easy: you probably just need one or two sentences
like if I say "all men are created equal", that doesn't mean I have to literally check it for every person on earth
lemme write the full answer and ask for your advice
sounds good
21:40
@JohnJiang: What are you doing here?!!
helping me lol :D
Well, that's good enough an answer :)
Hi @Alessandro
Hi Ted, could you take a look at this ugly problem of mine? math.stackexchange.com/questions/2263365/…
I thought I'd help someone as an entry ticket:)
though it's not clear if I helped or not
21:55
i can place a bounty on it ifyou like
ha, no worries. I am not that desparate yet:)
thanks for the offer though
@TedShifrin: my solution might be ugly, but the original problem is quite natural, and comes from representing probability distributions as points on the simplex

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