- #36
berkeman
Mentor
- 67,122
- 20,030
TIL (I had to look it up).caz said:And once again Godwin’s law stands
TIL (I had to look it up).caz said:And once again Godwin’s law stands
TIL(me too).berkeman said:TIL (I had to look it up).
Bystander said:TIL(me too).
There is no LaTeX Guide on Facebook. QED.JT Smith said:I'm kind of surprised there is still a Physics forum. Hasn't pretty much everything transitioned to face book and the like?
NO, NO, and NO. Well, OK, maybe a lot has but some of us have NOT.JT Smith said:Hasn't pretty much everything transitioned to face book and the like?
Facebook. . . ??I'll have to look that up. . . .JT Smith said:Hasn't pretty much everything transitioned to face book. . .
Me too, perhaps people here feel threatened by their brother-in-law’s deep scientific insightsJT Smith said:I'm kind of surprised there is still a Physics forum. Hasn't pretty much everything transitioned to face book and the like?
Is the alternative just some value that ##f## approximates for sufficiently small values of ##\theta##?ergospherical said:Yay, you are a physicist! although the second one ought to be ##\dfrac{1}{2}R^2 \sin{2\theta}##
(the alternative answer was ##r\theta## )
I remember Usenet. Every unmoderated group degenerated into a cesspool. The first of many disappointing discoveries about the nature of some people.JT Smith said:Maybe this is an age/generation discriminator. Godwin's Law dates back to the era of Usenet forums.
I'm kind of surprised there is still a Physics forum. Hasn't pretty much everything transitioned to face book and the like?
+1 on that. For keeping up w/ remote grandkids it's great. For science it's just a joke.Hornbein said:FAcebook? No face value.
"Farcebook?"OCR said:Facebook. . . ??
Possibly interesting reading:jedishrfu said:Not a misconception but a confusion. We were taught r theta phi in math. But American physics now uses the r phi theta convention to be in sync with European physics.
Spherical Coordinates
Tevian Dray and Corinne A. Manogue (Oregon State University, tevian@math.orst.edu and corinne@physics.orst.edu) have a proposal.
The problem. Nearly everybody uses r and θ to denote polar coordinates. Most
American calculus texts also utilize θ in spherical coordinates for the angle in the
equatorial plane (the azimuth or longitude), φ for the angle from the positive z-axis
(the zenith or colatitude), and ρ for the radial coordinate. Virtually all other scientists
and engineers—as well as mathematicians in many other countries—reverse the roles
of θ and φ (and use some other letter, such as R, for the radial coordinate).
Why is this a problem?...
ergospherical said:That reminds me, here's a test to see whether you're a physicist or a mathematician at heart...
if ##f(x,y) = xy##, what is ##f(r,\theta)##?
...
Here’s our favorite example:
Suppose ##T(x, y) = k(x^2 + y^2)##. What is ##T(r, θ)##?
We often ask this question of mathematicians and other scientists. Some mathematicians
say “##k(r^2+\theta^2)##”. Many mathematicians refuse to answer, claiming that the question is
ambiguous. Everyone else, including some mathematicians, says “##kr^2##”. One colleague, who
holds a split appointment in mathematics and physics, simply laughed, then asked which
hat he should wear when answering the question. What’s going on here?
...
Just to take a tangent, do you know how to tell if someone is a plumber or a chemist?ergospherical said:here's a test to see whether you're a physicist or a mathematician
ergospherical said:That reminds me, here's a test to see whether you're a physicist or a mathematician at heart...
if ##f(x,y) = xy##, what is ##f(r,\theta)##?
Yes, a perfect illustration. Once again the Mathematicians are correct, exactly, precisely correct. But the people that need to use the math to solve problems leave out the tedious rigour only retaining the essence that is useful and tailored to their particular field. Then they add in, but don't talk about, some jargon or assumptions that are always made by their peers. Which is why none of us find it easy (or possible) to read the papers from the "other guys". I think it's actually a pretty efficient system. There are good reasons that people take shortcuts, you know, the good ones anyway.fresh_42 said:Exactly. The difference between mathematics and physics is not so much in what is taught, and even less in the instruments, they use. The main difference is simply that it is another language.
Oh, I get it. In the case of ##\tilde{\mathbf{f}}##, you use the substitution ##x=r\cos\theta,y=r\sin\theta##, but in the case of ##\mathbf{f}##, you just substitute ##x=r,y=\theta## without making any allusions whatsoever to polar coordinates.ergospherical said:thinking too hard
My spell checker is set on "American". You cannot imagine how many "u"s I've deleted thru the years. I'd say there is a u in it, at least as long as you don't clean up the more important mess. Otherwise, we may start calling it Pittsborough.vela said:Actually, I was going to go with favorite doesn't have a u in it.
You mean there are no shortcuts to mathematics?vela said:Favorite misconception: The short version of mathematics is maths.
How about ##f(\pi, \tau)##? I think some will assume ##\pi## is just a symbol.robphy said:Possibly interesting reading...
https://bridge.math.oregonstate.edu/papers/bridge.pdf
Bridging the Gap between
Mathematics and the Physical Sciences
Tevian Dray and Corinne A. Manogue
Bystander said:"Farcebook?"
So wait, is the spherical coordinate system I learned in engineering calculus different than what physicists use? We learned ##\rho## ##\phi## ##\theta##.PeroK said:Exchanging the roles of ##\phi## and ##\theta## in my use of spherical coordinates was a seminal moment in my transition from amateur hack mathematician to amateur hack physicist
Well, what about the order of evaluation? I learned it a certain way, and have never thought differently about it. But there is certainly more than one way to skin a cat.Office_Shredder said:This is madness. The x-y plane is defined by ##r## and ##\theta##, adding a third dimension doesn't change that. If you switch polar coordinates to ##r## and ##\phi## then I have no problem with this convention.
I prefer whichever way makes the solution easier. Mind that you do have to do it correctly. But you really ought to be comfortable with multiple ways so you can choose the best.valenumr said:Well, what about the order of evaluation?
This only happens to famous skeletons, and only if someone who is alive starts it!rsk said:"Miss you know sometimes when someone dies and they put them in their tomb or whatever and they come back to life again? How does that happen?"
Sorry, what's that? (maybe the first one on the list below?)rsk said:I repeat. I blame the IPC.
I had the same question. But then I decided that International Plumbing Code perfectly fits.berkeman said:Sorry, what's that? (maybe the first one on the list below?)
https://acronyms.thefreedictionary.com/IPC
View attachment 293509