@0celo7 Best Subway: going to a better sandwich restaurant.
Though I suppose your suggestions is an acceptable alternative in a dire emergency such as being trapped in a airport departure lounge during a thirty hour delay.
@tpg2114 As part of my own research, I just came across a paper published this year, with the sentence "relativistic hydrodynamics of turbulent flows is still in its infancy, although some preliminary numerical results have already been obtained." It gives exactly 3 references, all of which I read trying to answer your question.
But their Figure 2 is where they claim it is -5/3 and I disagree. It isn't flat through the inertial range with that scaling. Their text says they tried two other common scalings and they were bad, so they went with -5/3
I don't think it's particularly good though, there's a "pileup" of energy at either end of the spectrum and a dip in the middle
Hi. In a 1-d ball physics problem (i.e. ball throw up/down), say ball is throw down, and it bounces back $\frac{3}{4}th$ its height, but how to find the time taken to reach that height?
I was reviewing a post now and due to certain flaws of the post, I had to flag it. Just then I saw this message at the bottom of the flagging window.
I checked my flagging history by clicking on the "review" link given in the message and this is what I saw...
So my question is: Is 1 declined...
I just think the homework-and-exercises meta-violation should be retitled "insufficiently conceptual" (or some synonym, "too particular")... The "infraction description" makes it clear that this is what the infraction is about, even though the title of the infraction is misleadingly labeled 'homework.'
@ChrisDrost I'm not sure what exactly the "title" of the infraction is. There's just a close banner saying the question is "off-topc" and then comes the close reason text. For that text, I like tpg2114's suggestion to just remove the "homework-like" from that text without substitute better than any renaming.
I need questions to practice. Any recommended book with good exercises covering following topics ?
1) Linear motion ,V-T graphs
2) Relative velocity , Relative Acceleration
3) Circular motion
4) Projectiles
5) Simple Harmonic Motion
6) Center of Gravit
@ACuriousMind This summer is the PC building summer.
It's gonna happen.
Gotta look forward :)
PHYS 555 - Solid State Physics
3 Credit Hours Elementary solid state physics. Crystal structures, reciprocal lattice, bonding in solids, energy bands, semiconductors, phonons, free-electron-gas theory of metals, superconductivity, magnetism, and other forms of broken symmetry.
:O
> Topics vary according to interest of students, instructor, and present state of physics.
@ACuriousMind: that's actually not a bad idea, yes.
@ACuriousMind the only thing that I don't like about it is that it kills the context for the phrase "work through the problem." A clear conceptual question doesn't need any effort to work through it.
A better phrasing might be "We expect specific, conceptual questions: every question should ask about a specific physics concept. In particular, questions about practical problems should show some effort to work through those practical parts to an underlying conceptual question. We want our questions to be useful to the broader community, and to future users. See our meta site for more guidance on how to edit your question to make it better."
I'm not sure I agree. Something like "I heard Brian Greene talk about falling into a black hole and appearing in another universe; is this possible?" is not amenable to "working through the problem."
@0celo7 That's from a similar era as the 11c and 15c (for people with much more money than I had then), but it doesn't seem to have developed the loyal following. Don't know why.
Maybe, or maybe "In particular, questions about practical problems" should be something like "Questions about particular situations" or "particular set-ups" or so.
tpg2114 just replied to me pointing out another thing, which is that we might expect pure-conceptual questions to explain the context in which they occur, like "I know that there is this common explanation out there but there are also these other problems with that, so is there a better way to understand this?"
@Slereah https://en.wikipedia.org/wiki/Tomorrowland_(film) I recently looked at this "Casey realizes that a side effect of utilizing tachyons to obtain information about the future is that it introduces a backfeed into the time flow. It makes the future it shows all the more likely to occur, creating a self-fulfilling prophecy"
and this caused me to draw the following:
(I'll do the maths later, but I am not sure if my pictorial analysis is qualitatively correct...) Special Relativity with tachyons Both observers agree the following: 1. Any observers that is in relative motion wrt them will detect the history change earlier than them (hence time constriction instead of time dilation), but can always relay the information < = instantanous (for simiplicity, we restrict all communication channels to sublight to light speeds) 2. The observer is then informed by the moving observers that history has changed
@ACuriousMind I asked Denzler about that Sp(2)=torus problem. Holy crap he derived Iwasara decomposition from scratch, then said "that's a neat result"
That thought process though...I could have never done that
Do I need to use the relativistic lagrangian if I am trying to show that "tachyons interacting with ordinary matter the initial value problem is ill defined"?
or the non relativitstic lagrangian is sufficient?
What other variables I need to set up the equation?
(I would like to try out this proof/derivation as an exercise)
@Slereah (but I am not sure what terms I need to put in for the lagrangian)
@Slereah What do you mean with "classical tachyon"? The tachyon field is a "field of imaginary mass", there is no classical particle associated with that.
@ACuriousMind: I'm trying to show that $\frac{1}{y^2} dx dy$ defines a Haar measure on the upper half plane using the usual identification $\mathbb{H}^2 \cong SL(2,R) / SO(2,R)$ but I am struggling
@ACuriousMind the exact one-forms $\omega=a\mathrm{d}\theta+b\mathrm{d}\phi=\mathrm{d}f$ on the torus have to satisfy $f=\int a\mathrm{d}\theta=\int b\mathrm{d}\phi$, right?
also $\int_{S^1}a\mathrm{d}\theta=\int_{S^1}b\mathrm{d}\phi=0$
Well, the usual procedure I know for getting the Haar measure on the Lie group is by just picking a volume form at the identity. It extends to a left-invariant form on the entire Lie group, and is right invariant for many groups
I've never explicitly calculated that the measure that results is invariant, I think, since it follows abstractly at least for compact and semi-simple groups.
The left-invariance is always there. (Or the right-invariance, but not the left-invariance, if you for some reason think the Lie algebra should be the right-invariant vector fields)
I've never dealt with a Haar measure not on a Lie group, and there it's very easily induced by a volume form. It gets difficult when the group is only topological.
I was reviewing a post now and due to certain flaws of the post, I had to flag it. Just then I saw this message at the bottom of the flagging window.
I checked my flagging history by clicking on the "review" link given in the message and this is what I saw...
So my question is: Is 1 declined...
I need questions to practice. Any recommended book with good exercises covering following topics ?
1) Linear motion ,V-T graphs
2) Relative velocity , Relative Acceleration
3) Circular motion
4) Projectiles
5) Simple Harmonic Motion
6) Center of Gravit
