The h Bar

Secret

14:00

This helps me to e.g. grasp the inner product when it is not the standard one,, because you are changing some parameters or properties of the maths object

I once spent a week trying to derive a mathematical object that can incoprate division by zeor, simply because I am curious and for no other reason

only to be more convinced why division by zero is not useful in the end, so I learnt something in the process, I guess...?

bolbteppa

@Secret I think what you're doing is just playing with the fact that the additive group of integers remains a group when you go to the quotient group mod 2, more specifically just looking at the fact that $(\mathbb{Z},+)/~ = (\{0,1\},+_{\mod 2})$ is closed...?

Secret

so 0 is the identity here?

ACuriousMind

@Secret The assignment of "odd" and "even" to numbers is formally called a $\mathbb{Z}/2\mathbb{Z}$-grading (see $G$-graded algebras‌)

bolbteppa

Sorry, can't get the ~ to show up in that

Secret

@ACuriousMind I see, guess I learnt something new today

bolbteppa

14:06

That is just a way to split $\mathbb{Z} = Odd+Even$, in this case it's the same thing as just putting even into the $\overline{0}$ class etc...

Secret

ok that makes sense (glad they taught us modular arithimetic back in my linear algebra course)

bolbteppa

Modular arithmetic written as $a = nm + b$ is incomprehensible, written as as $a = b + mn$ it makes perfect sense, I hope I'm smart :\

Secret

can we actually have non abelian modular arithmetic?

ACuriousMind

@bolbteppa Indeed, but the nice thing about formulating it as a Z/2Z-grading means that this gives you an immediate way to generalize the concept of "even" and "odd" to e.g. Grassmann algebras.

bolbteppa

Sorry the important thing was switching $a = nm + b$ into $a = b + nm$

Good point

ACuriousMind

14:11

@Secret "Arithmetic" would rather by definition be something over Z, so abelian, but of course you can divide out arbitrary normal subgroups out of groups. The notion of quotient group generalizes the idea of "integers modulo n" to arbitary groups in the sense that the integers modulo n are just the quotient of Z by the subgroup consisting of multiples of n.

Secret

@Acuriousmind 2nd comment: makes sense

@ACuriousMind So using what you said, Z/3Z will be basically consist of "even", "odd" and<insert name for the third even/odd behaving thing that is not even nor odd>?

bolbteppa

I wonder what's even:

ACuriousMind

@Secret Well, no, it makes no sense to call things in Z/3Z even or odd since 1+1=2 mod 3, so 'odd' times 'odd' would be neither even nor odd, which destroys the former defining properties of 'odd' and 'even'

Secret

ok

bolbteppa

@skullpetrol does he think it's okay to divide by zero?

skull petrol

14:17

No @bolbteppa but he can't explain why not.

Secret

My brain wiring must have accidentalyl crossed somehow...
I tend to treat a maths problem like a physics problem and a physics problem like a maths problem

1) Maths problem

$$blah+blah=djdfjh$$
$$r*r*e=e$$

My impression: O look, there's an interesting phenomenon here, and it obeys the rules and properties as shown

Manipulating some algebriac expression

My impression: Let's see what happens if I throw in this, and take out that

2) Physics problem:

for example:

0celo7

@Secret what are you going on about

bolbteppa

:\

Secret

step 1: Draw a diagram with the known and unknwons on it
step 2: convert the word descriptions into maths relations
e.g. charge has to be positive means q > 0
step 3: After getting everything converted into maths relations and constraints, focus only on the maths and then deirve the answer, THEN interpret it
---
umm, just my typical way of doing exercises and problems, and sort of explain why I sometimes spent more time than my peers to solve them

So basically the reason why my physics sucks is because when facing a mathematical object, I thought I am doing some abstract experiments and th maths objects and operations are chemicals and parameters I can adjust to influence the outcome

while when doing a physics problem, because I am bad at assumptions, I just convert everything into maths, bang through the algebra and then get the required answer in the end, only then I start to interpret what it means, hence I get lost in the maths easily

Tl:dr I found I do physics like a mathematican, but maths like a physicist, which does not sound really efficient...

0celo7

At least you're not doing math like an engineer

Or engineering like a mathematician

bolbteppa

14:25

Maths is a language, every mathematical step is just a shorthand for some words, every step can be interpreted

Secret

@0celo7 lol

bolbteppa

@Secret even something so loaded with algebra as the process of separation of variables in solving a PDE can actually be visualized if you push your math hard enough physics.stackexchange.com/questions/151383/…

at every step of the way

0celo7

“FIRST DEMOCRATIC DEBATE HIGHLIGHTS: 2015” —- A Bad Lip Reading of the First Democratic Debate

►

ACuriousMind

@dmckee: Weren't you recently talking about this?

Secret

well, some of the physics things are often not written explicitly in maths

we have simple things such as time must be positive, to more subtle things such as you cannot have reflection here because it was being absorbed by the surface

When I do problems, rather than writing words to state which solutions I discard, I wrote all the conditions and relations out and let the equations to tell me what solutions I discard

This is contrast to how a typical physicists do problems, they have no problem discarding the irrelevant solution by writing some words, but for me, like a dumb program, the …

@bolbteppa Nice, didn't know that. Should favorite for future reference

bolbteppa

14:35

@Secret there's nothing wrong with what you're doing

If you read a different book discussing the same problem you'll most likely find the answer you wanted, it may take looking in 50 to find it though

Secret

Well, I just need to trian myself to be more comfortable and bold with using assumptions, and not to be too focus on the rigor when doing physics problems, else I will spent too much time in doing algebra and peple will fail to understand my workings

bolbteppa

I think you should just try to physically interpret your algebra and eventually you'll get to the point where you can skip this stuff because it'll be obvious

I found that geometric interpretation of separation of variables by not being happy with all the algebra

JokelaTurbine

I just realized that Earth doesn't rotate at all, liveleak.com/view?i=82b_1445156056 ....you know, othervice the 7th heaven wouldn't fall to Kaaba and also airplane traveling to china would just not make any sense.

0celo7

@JokelaTurbine Interesting!

JokelaTurbine

@Ocelo7 I hope you looked the link,,, There is a brilliant comment under that; "Don't forget that he live in the 7th century. Nicolaus Copernicus came at the 15th and Galileo Galilei at the 16th. It's just unfair of us to expect him to know!!!"

0celo7

14:50

@userØØ7 either \mathbf or \vec. Not both. — dmckee ♦ Jun 5 '13 at 4:45

@dmckee My lecture notes use both simultaneously.

skull petrol

I think he has you on ignore :P

Secret

Well, my issue with assumptions is that often I am oblivious to things like "the component of the friction has to be less than blahblahblah", "q must be bounded between a and b", "Aexp(x)+Bexp(-x) and A must be 0 else the solution will blow up"

Basically, any extra condition that is there because of the requirements of the physical situation. If the maths is looked at purely in the maths context, there is nothing in the rules that tell you you must make these assumptions

0celo7

@skullpetrol Really?

skull petrol

We'll find out.

0celo7

How can a mod put someone on ignore?

Furthermore, why would he?

bolbteppa

14:55

Wow, that is so funny

skull petrol

We can put them on ignore

Secret

So my issue is something like a generlisation of "solving projectile motion and then the ability to know that you need to rule out the negative time solution as it is irrelevant to the problem, even if it is a solution mathematically speaking"

Disclaimer: I can rule out the negative t soution of course, the above is just an example on what I am trying to say

0celo7

Yes, but a mod has to be able to read what we say.

skull petrol

Other mods can

bolbteppa

@Secret what's wrong with your $A = 0$ example, why is that so hard to understand?

0celo7

14:57

Why would he put me on ignore? I see no reason.

skull petrol

He did talk about his mod night stick

^not a good sign.

bolbteppa

haha

0celo7

He was extremely vague last night. I still don't know what he meant by...anything he said.

Secret

It's just an example, I can handle that case nowadays

But what I am trying to say is like this:
Back then, in 2nd year when solving the particle in a box problem, I treat the problem as solving an ODE. Therefore I solve the ODE as if I am having an ODE course (listing out all the steps) and get the general solution. After considering the boundary conditions, I then got stuck because there is nothing in the question that says I need to set A=0 else the solution will blow up

bolbteppa

Yeah it's everyone elses fault and problem

skull petrol

14:59

Perhaps I'm over reacting.

Lad + machismo = ?

Secret

@bolbteppa Basically, my problem is, if the maths and the question don't told me I need to make an assumption, and if that's the first time I do the problem, I often failed to see the assumption I need to apply

0celo7

@skullpetrol If he's ignoring me, I'd like a reason. I can handle people not liking me, but for the life of me, I don't see why it's acceptable to not give an explanation/notice.

Take @bolbtepa or whatever his name is.

He doesn't have to bother talking to me anymore.

We have an agreement.

skull petrol

Just sit back and wait and see pal

JokelaTurbine

Who is able to Ignorance, is reliefed; "You are no bigger than the things that annoy you." Jerry Bundsen ---- and this doesn't need any reason. Everyone is aloud to decide how uses his/her own time.

bolbteppa

Basically, I help 0celo with questions and then call him out when he insults a child in the news for no reason and he blocks me, then goes off annoying other people too, but somehow I have an agreement with him, bizzare...

Huy

15:04

@0celo7 why u mad

0celo7

@Huy I'm not mad.

Huy

u sure bro

u seem like it

ACuriousMind

@0celo7 (and @skullpetrol) You're being ridiculous, dmckee is not ignoring you, he's not even in chat right now.

Huy

im very good at reading ppl

bolbteppa

This is what I meant about the linear-algebra-inspired downward spiral, the stress of being expected to know rigorous linear algebra in difficult books when all you're doing is a basic Anton course would drive anybody to lash out haha

skull petrol

15:05

Machismo

Machismo (/məˈtʃiːzmoʊ, mɑː-, -ˈtʃɪ-/; Spanish: [maˈtʃizmo] (from Spanish "macho", male); Portuguese: [mɐˈʃiʒmu]) is the sense of being manly, the concept associated with "a strong sense of masculine pride...[with] the supreme valuation of characteristics culturally associated with the masculine and a denigration of characteristics associated with the feminine." It is associated with "a man’s responsibility to provide for, protect, and defend his family." In American political usage, William Safire says it refers to the "condescension of the swaggering male; the trappings of manliness used ...

bolbteppa

@Secret this whole $A = 0$ thing comes up when you solve pde's as part of the process of determining the constants of integration, sometimes you do it on the function, sometimes you take a derivative and then do it, it's part of the general process of fitting a general solution to a pde to boundary conditions, if you went through a basic PDE book like Strauss you'd get tons of practice with this method, further you'd be able in advance to predict it in the particle-in-a-box example

0celo7

@ACuriousMind How am I being ridiculous?

I said he's not ignoring me.

bolbteppa

since you're solving Schrodinger's PDE, you'd know in advance the tools you're going to need, and you'd have practice in advance

It even comes up in ode's, but I too remember it coming up when dealing with pde's

0celo7

@Huy Where?

Huy

here m8

calm down

im here to help

0celo7

15:07

What does "machismo" have to do with anything?

skull petrol

@ACuriousMind he gave him a lecture yesterday about being macho with his lads in the chat room.

0celo7

There was no "lecture".

ACuriousMind

@skullpetrol lol, that was not a 'lecture'.

0celo7

He said three very vague things and then disappeared.

I don't even know what he means by "insults"

skull petrol

Lads = friends

bolbteppa

15:09

@0celo7 I find it pretty funny that you are talking about wanting an explanation from someone for apparently ignoring you, when you never even bothered to explain to me why you blocked me after I helped you numerous times, unbelievable projection...

0celo7

Sure @ACuriousMind has long hair

That's an insult?

skull petrol

Recall what he said about how far being smart will get you in life.

0celo7

I'm still confused how you get "he blocked you" out of that

bolbteppa

@Secret also I'm sure you can see the physical motivation behind setting $A = 0$ or whatever the problem requires, overall you just want to specify the constants of integration, and any old trick will do really, this is why it's so hard to solve pde's, specifying boundary conditions

ACuriousMind

@0celo7 Some of the stuff that you, Danu, I and possibly others say to each other here would be insulting if you said it to random people who took it literally and not as tongue-in-cheek as it is meant.

skull petrol

15:12

It takes diligence and hard work.

0celo7

@ACuriousMind I honestly have no clue what you're talking about

bolbteppa

Wow

ACuriousMind

@0celo7 Uh, really?

Let me see...

Sep 13 at 17:18, by 0celo7

I can imagine him shanking a dude in a crowd, on the other hand

0celo7

@ACuriousMind Yes, really

Huy

lol

0celo7

15:13

That's not an insult!

You could be a hitman physicist!

ACuriousMind

@0celo7 If you take it literally, you called me a murderer there. That is an insult.

skull petrol

Is it a compliment?

Secret

@bolbteppa For first time problems (like the particle in a box problem when I was just year 2) I often failed to see the physical motivation until I learnt the existence of the assumption (e.g. A=0)

That is, if I don't know the assumption beforehand, I am often oblivious to the physical considerations

It gets better with experience, but this is something I am weaker than my peers

0celo7

@ACuriousMind No, I called you a potential murderer :P

And that was out of context, anyway

See, we were talking about football riots

skull petrol

Raiders style.

0celo7

15:15

yup

skull petrol

We beat the jets

0celo7

being willing to shank someone over a football game is a great virtue

you know what the skins did?

I haven't been paying attention to them :/

skull petrol

:(

ACuriousMind

@0celo7 You are completely missing the point here.

(not the point of my knife, though)

Secret

Having done the particle in a box problem for many times, of course nowadays I can see why and how A=0

But issues of similar nature still exists in my case and I often rely on doing my examples to sharpen my skills to notice where to make assumptions or physical justifications

0celo7

15:16

@ACuriousMind heh

bolbteppa

@Secret well in this case it is clearly a case of you studying stuff in year 2 that required a (year 3/4?) PDE background to appreciate, before you'd studied PDE's, leading to confusion about basics, and that's okay but this is exactly why I studied math and not physics in the beginning, to avoid my thinking being muddied by these types of things, I know this is small, but it's so annoying haha, a great example, my advice is to not let these small things worry you,

treat this as an aspect of a general method

0celo7

@skullpetrol oh they beat the bucs!

skull petrol

Nice

The all blacks won the World Cup

:D

0celo7

lol the bucs are 2-4

not a great victory

bolbteppa

@Secret I mean, if you think rigorously then all you need is math to be able to formulate that, and you were expected to do things sloppily but you need rigor to be comfortable, I've noticed the best physics book writers think this way too, so you should wear it as a badge of honor

0celo7

15:19

@ACuriousMind perhaps

bolbteppa

I think the point was he was saying silly things about general relativity and stuff while at the same time asking basic linear algebra questions

0celo7

but I still don't understand what his comment about "self awareness" was about

bolbteppa

Finding it hard just like the guys students but also saying crazy things like some other internet person saying similar things

0celo7

@skullpetrol lol we're against the Patriots next

we're probably going to get destroyed

bolbteppa

@Secret I can only advise you to read Landau and Goursat to stop these problems happening tbh, if you want first principles physics thinking coupled with the math behind it

skull petrol

15:25

@0celo7 Brady's on fire.

He needs a few good sacks.

Secret

https://www.google.com.au/search?q=Landau+and+Goursat&es_sm=93&biw=1920&bih=955&source=lnms&sa=X&ved=0CAYQ_AUoAGoVChMIuamhlIbyyAIVS95jCh17Lgfz&dpr=1

which boook, is it the complx function theory one?

ACuriousMind

@0celo7 The person he was talking about is "less self-aware" than you because they would have been unable to even consider that description might apply to them, but you immediately felt the need to comment that that description doesn't fit you, i.e. you are self-aware enough to take the statement and check whether you fit it before you dismiss it.

@0celo7 The "Shocking, I know" then just was a joke implying your self-awareness isn't high to begin with, which is a pointless friendly insult of the kind he talked about afterwards :P

skull petrol

Get work Sherlock

:P

0celo7

I felt the need to respond because I thought it was directed at me

The first half seemed like a reasonable complaint

bolbteppa

@Secret en.wikipedia.org/wiki/Course_of_Theoretical_Physics en.wikipedia.org/wiki/%C3%89douard_Goursat (15 books total! :D)

skull petrol

15:28

But it spiraled downward into introspection.

0celo7

Then I thought he was referring to the "QM is wrong" thing

@skullpetrol Not really, because I still don't know what he meant by "self aware"

ACuriousMind

@0celo7 'Twas not at all directed at you at all, I know who he was talking about (but I won't tell you because dmckee comes to chat to rant about such things without identfying the user he's talking about).

bolbteppa

Try criticizing well-established theories while struggling with linear algebra?

dmckee

@0celo7 Well .... hmmmm .... OK. I think that is rare, and to my eye it looks really bad.

0celo7

@ACuriousMind Hmm, did you leave before the convo ended? We established who it is.

@dmckee I agree.

dmckee

15:30

@ACuriousMind Yup.

ACuriousMind

@0celo7 I wasn't even here for that conversation, I read it in the transcript to see what the hell this weird conservation betwenn the skull and you was about.

skull petrol

@dmckee does self aware mean introspection?

::crickets::

dmckee

@skullpetrol Yes.

skull petrol

@0celo7 QED^

:P

0celo7

QED WHAT

skull petrol

15:35

Now you know what it means.

0celo7

I obviously don't know what you're talking about, so continually being vague is not accomplishing anything.

ACuriousMind

Quantumelectrodynamics is obviously highly relevant here.

0celo7

@ACuriousMind Let's return to something that has been mystifying me. The Grassmann algebra is the quotient of the tensor algebra by the ideal generated by elements of the form $v\otimes v$. Is this correct and what does it mean?

The tensor algebra is $\oplus_n (V^{\otimes n})$ for some vector space $V$, $v\in V$

In that statement, is the $\otimes$ in $v\otimes v$ the standard tensor product?

ACuriousMind

Yes, everything is correct. What's your question about it?

0celo7

> what does it mean?

I know the Grassmann algebra as the algebra of alternating tensors.

How are these statements equivalent?

ACuriousMind

15:42

Uh, the algebra of alternating tensors is defined the same way.

0celo7

Why is the algebra of alternating tensors the quotient of the tensor algebra by that ideal?

1

Q: Why does the work-energy theorem need to include internal forces?

Can anyone kindly explain me why work energy theorem must also include internal forces? The proof of work energy theorem is derived from Newton's laws of motion, but Newton's laws of motion don't take internal forces into account, so why should internal forces be taken into account in the work e...

ACuriousMind

Because dividing out the ideal generated by $v\otimes v$ is the same as imposing the relation $v \otimes v = 0$ upon the tensors.

0celo7

What? Of course Newton's laws take internal forces into account...

@ACuriousMind So this turns $\otimes$ into the antisymmetric $\wedge$?

ACuriousMind

@0celo7 Yes. I feel we've had this discussion before

0celo7

@ACuriousMind Yes have

> Let's return to something

dmckee

15:46

@0celo7 Well, in many cases there are symmetries that allow us to ignore them for various purposes. The conservation of momentum can be expressed as a requirement that internal impulses sum to zero, for instance. People have simple overgeneralized that idea.

0celo7

Ok, now for the real question. Why does the multiplication rule $vw+wv=-2\langle v,w\rangle$ follow from the definition of the Clifford algebra as the tensor algebra quotiented by the ideal $v\otimes v+\langle v,v\rangle^2$?

@dmckee Ignore them because they cancel out?

Newton's second takes every force into account.

And once you understand that, I think the work question becomes trivial.

@ACuriousMind Ok, in the multiplication rule if I set $w=v$, then I get the ideal.

@ACuriousMind But I could also have a term $(w-v)(w-v)$ in the multiplication rule that would also satisfy the ideal condition, no?

ACuriousMind

@0celo7 Not entirely correct, the ideal is $v\otimes v + \langle v , v \rangle$ without the square. Quotienting out the ideal means imposing the relation $v\otimes v = -\langle v,v\rangle$. Thus, $(v+w)\otimes(v+w) = -\langle v+w,v+w\rangle$. Substracting $v\otimes v + w\otimes w = -\langle v,v\rangle - \langle w,w \rangle$ from both sides give the commutation rule.

0celo7

Square was a typo

@ACuriousMind Ah, I see. Thanks

@ACuriousMind How much calculus of variations do you know?

ACuriousMind

Only what physicists usually do.

I.e. none, strictly speaking :P

0celo7

I was talking to an engineer who does optimal control, which is basically calculus of variations

It's actually quite complex, but his (engineering) course doesn't get into the gory functional analysis

I've heard it's useful in PDEs, too

dmckee

15:58

@0celo7 It ought to be trivial, it clearly is not trivial enough.

0celo7

@dmckee So I'm not sure why you needed to write what you did. Just explain that $F=ma$ takes $F=\sum_{\text{literally everything}}F$ and then prove the theorem!

dmckee

@0celo7 When people are arguing about the meaning of words, you have to show not only that the meaning you favor is internally consistent, but at least one of (a) that your meaning is much more widespread among exerts than their or (b) that their meaning is not internally consistent.

0celo7

16:21

@dmckee Ah, I see now. They were arguing about which kinetic energy is needed.

dmckee

@0celo7 Yep.

0celo7

@ACuriousMind Wodka

0celo7

16:48

There is good reason to believe that the administration of justice is infected by predictable incoherence in several domains. -- Daniel Kahneman

John Duffield

17:28

@bolbteppa : not off the top of my head, I'd have to look it up. The important issue here is what is energy? A mathematical physicist might give you a tautological non-answer saying energy is the capacity to do work, and work is the transfer of energy. But he's merely defining one term in terms of the other, and he isn't delivering any understanding.

Slereah

MY PREDICTION CAME TRUE

You may call me Nostradamus

Man, both came true

Amazing

John Duffield

@skullpetrol : I've told you this previously. Division is asking how many of these there are in that? And there is no number of zeros in some other number. So division by zero yields an undefined result.

@bolbteppa : I said maths relatively weak. Who was admonishing me?

bolbteppa

@JohnDuffield this is what I randomly read, science20.com/comments/171172/Re_I_am_a_bit_unsure_of_how_to that's all, but you just gave me a Newtonian mechanics definition of energy when I asked you about Lagrangian mechanics, do you understand the Lagrangian mechanics concept of energy via symmetries?

@JohnDuffield Also, calculus-based physics books define work in terms of forces and link it to energy via the 'work-energy theorem', justifying the link, why define things tautologically when good books don't do it that way?

0celo7

17:58

@Slereah Huh?

Slereah

18:14

5 hours ago, by Slereah

I imagine now Duffield frenetically looking up on wikipedia the formula to copypaste it

5 hours ago, by Slereah

He will probably just go "The math isn't important!", as usual

0celo7

ah

@ACuriousMind what the fuck

@ACuriousMind holy crap what is happening

ACuriousMind

I am not a hardware technician.

0celo7

it's borke man

Huy

rip

0celo7

it settled down to 800 o.o

ah it shot up to 3000!

@Huy yes

@ACuriousMind really??

@ACuriousMind why didn't you tell me this earlier

Nova

19:29

Hi everyone. So I think I am struggling with a fundamental concept. What IS the charge of an electron? Is it positive or negative 1.6*10^-19?

C*

0celo7

@ACuriousMind @Slereah The Maupertuis principle tells us mechanics $\Leftrightarrow$ geodesic problem on configuration space. The Einstein equations tell us free fall $\Leftrightarrow$ geodesic problem in spacetime. Is there a Maupertuis principle for GR? Can one recast the e.o.m. $\nabla_uu=F$ as $\tilde\nabla_u u=0$ (where $\tilde\nabla$ is some connection other than the Levi-Civita $\nabla$)?

ACuriousMind

21

Q: Why is the charge naming convention wrong?

I recently came to know about the Conventional Current vs. Electron Flow issue. Doing some search I found that the reason for this is that Benjamin Franklin made a mistake when naming positive and negative charges. There is even this little comic about that http://xkcd.com/567/ My question is, h...

electricity electrons charge current conventions

0celo7

@ACuriousMind @Slereah Does that question even make sense?

ACuriousMind

Geodesics as Hamiltonian flows

In mathematics, the geodesic equations are second-order non-linear differential equations, and are commonly presented in the form of Euler–Lagrange equations of motion. However, they can also be presented as a set of coupled first-order equations, in the form of Hamilton's equations. This latter formulation is developed in this article. == Overview == It is frequently said that geodesics are "straight lines in curved space". By using the Hamilton-Jacobi approach to the geodesic equation, this statement can be given a very intuitive meaning: geodesics describe the motions of particles that are not...

0celo7

@ACuriousMind Hmm, I don't think that's what I'm looking for.

Without any forces in CM, particles move on straight lines.

ACuriousMind

19:35

Yeah, wasn't sure either but I'm not sure what you're asking.

0celo7

Without any nongravitational forces in GR, particles move on "straight lines".

In CM, turning on a potential means particles travel on "straight lines".

What is the equivalent thing for GR

In GR we have $(g,M,\nabla)$. Suppose we have some force $F$ in spacetime. Does motion in $(g,M,\nabla,F)$ correspond to "free fall" in some $(\tilde g,M,\tilde\nabla)$?

@ACuriousMind That make more sense?

Nova

ACuriousMind, honestly, that post confused me even more. Is there a difference between the charge of a proton and the charge of an electron?

0celo7

@Nova Just the sign.

Nova

And if so, can that difference be represented by the switching from a positive sign to a negative sign?

0celo7

All that matters is that the sign is opposite.

Nova

19:38

OK, so here is the million dollar question.

0celo7

Solve Navier Stokes

Or Yang Mills mass gap

Danu

Oh, hey, interesting.

0celo7

@Danu Holy god

Nova

Is the potential of a battery that runs on negatively charged particles OPPOSITE than the potential of a battery that runs on positively charged particles?

ACuriousMind

@Nova What do you mean by "battery that runs on X charged particles"?

Danu

19:40

The barest essence of energy is a volume of stressed space :D

0celo7

"atoms are made of particles"

Oh lord

Nova

Ok, for some context, could you quickly scan my physics forum post?

ACuriousMind

@0celo7 I'm not actually sure you can add forces like that in GR. You should include the proper interaction term in the Lagrangian and have it contribute to the stress-energy tensor. GR is a field theory, while you are considering the particle version of classical mechanics. Not sure that mixes well

Nova

physicsforums.com/threads/…

0celo7

@ACuriousMind Er, Lorentz force?

Nova

19:43

Basically, I'm really confused about definitions. Electrical potential is defined as U/C

C can be positive or negative depending on the charge of the particle

0celo7

@ACuriousMind But you can still have e.o.m. like $\nabla_uu=F$ IIRC.

Nova

therefore, electrical potential is negative when C is negative and positive when C is positive

ACuriousMind

@0celo7 Yes, but doing that properly, you have to include the electromagnetic contribution to the stress-energy tensor, which changes the metric even before considering that there is now also an additional force

This then gets a bit messy

0celo7

@ACuriousMind Naturally.

ACuriousMind

So, I guess the answer to your question is: I don't know

Nova

19:45

In other words, lets just say I have a battery, a galvanic cell

0celo7

Well, I didn't think you would. :P But I had some hope that you would be like "oh this seems like a theorem due to X"

You make it go round and round

Danu

@ACuriousMind It doesn't really have to in a spherically symmetric vacuum case :)

Nova

lets say the anode is the standard hydrogen electrode (AKA V=0) and the cathode is some metal that is being reduced

0celo7

@Danu Great find.

Danu

The intro tune is great ^^

Nova

19:46

because its ELECTRONS that are flowing, the potential energy per CHARGE of electron IS: U/-C

am I crazy?

0celo7

I love how the host agrees with everything

ACuriousMind

@Danu ...why am I watching things about the UK election and the Scottish government protecting pedophiles?

Danu

@ACuriousMind ...because you like it?

0celo7

HAHA a picture of Einstein on the table

ACuriousMind

Smooth segue into beaming someone onboard for a conversation about physics.

0celo7

19:49

"round and round"

Can someone please explain

Danu

@ACuriousMind :D

Nova

Should I switch to the chemistry chat instead?

bolbteppa

@Danu wow, cool

Danu

@bolbteppa It came from your link ;)

0celo7

The Higgs has nothing to do with electron mass?

@JohnDuffield Citation please.

obe

19:52

I was gone for a while.

I missed you guys so much....

Danu

^ ehhh? Thanks?

ACuriousMind

@obe <3

0celo7

Haha an Einstein quote

bolbteppa

Jesus, at 7.50 he repeated the thing I just contradicted him on :\

2 hours ago, by bolbteppa

@JohnDuffield this is what I randomly read, http://www.science20.com/comments/171172/Re_I_am_a_bit_unsure_of_how_to that's all, but you just gave me a Newtonian mechanics definition of energy when I asked you about Lagrangian mechanics, do you understand the Lagrangian mechanics concept of energy via symmetries?

2 hours ago, by bolbteppa

@JohnDuffield Also, calculus-based physics books define work in terms of forces and link it to energy via the 'work-energy theorem', justifying the link, why define things tautologically when good books don't do it that way?

0celo7

I wonder, are the YouTube views the total number of times this video has been watched? Or was this aired on TV or something?

Slereah

19:56

I think it might be once per account?

Or IP, if no account

I dunno

0celo7

Unique views

Danu

It's definitely not once per account---think about what 1 billion views would mean.

bolbteppa

Another hour of this

0celo7

@Slereah y u no answer my geodesic question

you know all the random GR facts

bolbteppa

I'm guessing this is like an alternative science reject everything program, and the whole point is to bring him on to say things like energy has a circular definition when the establishment think about it?

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