It seems q_i is a position then, but susskind never defined this is what probably led to my confusion. I think that is cleared up now.
You're basically admitting that the
only experience you have of any of this is watching a YouTube video. If you'd worked through a book or a set of lecture notes then you'd be well aware of what various things mean, of alternative notation, of how things relate to one another. Instead when you say "I haven't seen that notation before" or the like what you mean is "That's not the notation used in this one video I'm using to answer your questions".
If the sum total of your knowledge on this stuff is from Susskind's video then how can you have been doing anything about the Dirac equation or gauge invariance or covariant properties of fields? All of them come
after basic Lagrangian material and Noether's theorem because they make considerable use of it.
It isn't 'confusion' you have, it's just not knowing. It's like me saying I'm confused about Japanese. No, I simply can't speak it.
Secondly when you gonna give it a break with the (Wolf) claim AN? That was four maybe five years ago.
I think it's an excellent demonstration of your willingness to misrepresent what people say. Not to mention a demonstration of how poor your maths abilities were at a time you claimed to be studying Riemannian curvature in general relativity. Do you now admit you lied about that?
And your reply doesn't retort any of my demonstrations of your misunderstandings and mistakes. You also ignored my question. It's simple enough, perhaps 2 sentences, no LaTeX, to answer if you're familiar with this stuff. But if the extent of your Lagrangian understanding is from a single YouTube video that would explain why you made the mistake and why you can't answer the question.
If you more often spoke to me like a level-headed human, I would be more inclined to answer your questions.
I'm not asking you because I don't know. I'm asking you because I know and you claim to know but you have provided evidence to the contrary. I'm giving you the opportunity to step up and demonstrate your understanding goes beyond mangling a single YouTube video.
Would you like me to repeat the question?
Oh (and not just a level headed human)... you might also notice the fact you came in here with a whole load of accusations!!!!
Which I explained in detail and which you have yet to retort, despite being given many opportunities.
Would you like me to repeat the question?
Actually susskind did.
I said to the physics subforum that in physics there is a noticable difference between perpendicular and orthogonal. If you wanna keep that one going up then fine... I find it interesting that cptbork didn't even know of this definition when I spoke about it, upon which he said I was decieving everyone.
Firstly isn't a difference between perpendicular and orthogonal, they are synonyms. Secondly I was referring to the whole "matrix times matrix gives number" fiasco. Susskind said "equals one" and you took it to mean the number one, despite the fact matrix times matrix gives matrix and Susskind went on to explicitly state in the following 30 seconds or so he was referring to the identity matrix.
Disingenuous crap.
Guest is not a physicist.
Lagrangian methods, variational principles, integrals, functionals, partial differential equations, groups, transformations, these are all things most mathematicians cover in their undergrad. Remember, I did mathematics as my degree. I covered Lagrangian methods and variational principles in the first term of my second year. It was a required course so every mathematician covered it, not just those interested in mathematical physics. Similarly all the other things I just mentioned are considered essential learning and appeared in more than half a dozen required courses in the first and second years. As such even if Guest is a purest of the pure mathematician he'll know about this stuff.
Secondly, why choose two people who are completely pro-you anyway? Could you have picked any more of a biased set of individuals?
I picked two people who are definitely knowledgeable in mathematical methods in physics. It is a coincidence they happen to agree with me and disagree with you so much. In fact
all of the people here educated to a high level in mathematics or physics are likewise.
Of course the fact they all happen to agree with me and disagree with you so much isn't really a coincidence. They, like me, see through your nonsense and dishonesty and hence don't hold you in very high regard. So it's not that I am picking biased people from the pool of formally educated mathematicians/physicists who post here but rather
all of said people have concluded similar things about you.
Why, if you were to use the scientific method you might even consider that evidence for the hypothesis that you spout nonsense a lot. After all, while correlation does not imply causation it certainly warrants investigation.
Do yourself a favor, watch the video if you are even going to throw accusations about. It seems only fair, eh?
You make it sound like I've only pointed out one mistake. I've pointed out a plethora and all you can manage is a weak attempt at a single one, the rest you're just avoiding entirely, just as you did in the Dirac equation case.
I've just realized that what I said to James concerning why the potential depended on q isn't such a far off guess. See, the q takes on the form
$$T = \frac{1}{2}m\dot{q}^{2}$$
Guess? Why would you need to guess? The form of kinetic energy and potential energy in Newtonian physics is known to school children!
Besides, that expression for kinetic energy is not universally true. There's other systems with different kinetic expressions. You should have seen a number of them if you had worked through quantum mechanics and into quantum field theory. For example, the expression in the Dirac equation for kinetic energy isn't of that form. Can you tell me why it can't be of that form? It's to do with something I told you about the Dirac equation. Again, I'm giving you an opportunity to show you can do more than parrot back facts you've heard from YouTube, you can show you have an actual grasp of how all these things fit together. Here's a chance to show all my accusations are not as valid as they seem to be.
Susskind defines it as a velocity... I will watch the video again at some point to clarify this is indeed the case, but, essentially velocity turns up in the kinetic representation $$T = \frac{1}{2} M \dot{q}$$. Unless of course susskind has used the two were one is in fact the position given as q_i in which case I apologize. He couldn't have defined that well.
It's quite clearly position. Susskind explains it in the video, the context makes it obvious. Kinetic energy is written as $$\frac{1}{2}m\dot{q}^{2}$$ and obviously if q=x then $$\dot{q} = v$$ and so you get $$\frac{1}{2}mv^{2}$$.
You shouldn't have prompted me to watch the video because it really does become so obvious you're just parroting Susskind. For example, when James asked you what a Lagrangian density is you just spewed out the equation Susskind wrote on the board early on. Except you introduced an error because you wrote the second term in terms of $$\dot{\phi}_{x}$$, when it is actually $$\dot{\phi}$$. Anyone familiar with scalar field theory knows such a term doesn't arise in the case Susskind is talking about (if ever). You also spewed out the expression involving the photon field, the bit involving A, ie $$\frac{1}{2}m\dot{x}^{2} + A \cdot v$$. Susskind actually uses very poor notation there, because he writes the velocity in two different ways in the same expression because $$v = \dot{x}$$. He makes this obvious when he does the partial differentiation and hits both terms in the same manner. You transcribed this mistake. And I can see why you can't answer my question about T+U, Susskind explicitly states the implication involves more work and its something he doesn't want to get into at that point.
You have said people here can read and hear and so can watch that lecture for themselves and see what you're saying Susskind says. What you don't realise (and this is a mistake you made with the whole identity matrix issue from one of his other videos) is that Susskind makes a lot of short cuts, a number of slip ups or doesn't explain things entirely accurately and that's not accounting for you not understanding him. Since you have no other source of information on this stuff, ie you haven't actually learnt it elsewhere and just citing Susskind, you're actually just parroting him, you don't spot any of these and you take what he says as gospel. It also means you can't tailor your answers to James's questions, you can only try to bend the question to some part of the video for you to reproduce, as was made clear by your answers to his first lot of questions. I wouldn't be surprised if that's James's intention, to get you to post more of your 'own answers' to highlight they aren't really your answers, they aren't a mix of different sources, they are just snippets of Susskind's video reproduced here. Since you'll reply to questions you think you know the answer to maybe James has a much better way of having you dig your own hole.