The first one is zip. It returns a container of tuples, the only limitation is that the container of the passed in objects should be the same.
If I'm reading the code correctly, zip() is copying all the containers into a tuple. This can be quite a heavy operation and often something one doesn't want to do (especially if one's just iterating over some containers, something that usually doesn't involve copying anything).
Next is a wrapper, to make reverse walking of a container through a range based for easy/possible.
If I'm reading the code correctly, it doesn't work for static arrays (even though a range-based for loop normally does).
So pausing the game to do it manually saves in-game time, even if it would otherwise be slower in realtime.
I really wish that authors of TASes of this game would stop paying attention to the "in-game time". It just ends up producing completely arbitrary rules on how much the pause screen can be used.
By abusing the pause screen, I'm sure that you could produce a 5-hour run that nevertheless is a few seconds faster from the in-game timer's perspective than the current best. But nobody would want to watch that. Therefore, the author will apply some completely arbitrary rules on how many times he uses the pause screen.
IMO wallclock time is all that counts.
If the angular momentum of the Sun is
S = 1.92*1041 kg m2 s-1
and the mass M of the sun is approximately 2*1030 kg, then:
radius = A/c = S/M/c = 320 m
Would that be about correct?
Question: A consequence of general relativity is that rotating objects "bend" their surrounding spacetime in such a peculiar way that they cause so-called frame dragging. (The spacetime is bent in such way that objects in the vicinity of the rotating body will tend to co-rotate with it.)
The spacetime in the vicinity of the event horizon of a rotating black hole is bent in the same way as if the event horizon where an actual solid object (rather than just empty space with a certain geometry). We can measure the "rotation" of the event horizon by measuring the geometry of spacetime in its vicinity. In other words, we can say that the event horizon is effectively rotating as if it were an actual solid object.
So the question is, does the event horizon "rotate" slower than the ring singularity, and by how much?
So what would the answer to my original question be? (In other words, if a typical star with a typical rotation speed were to collapse into a black hole, what would be the diameter of the ring singularity?)
Our sun is not massive enough for this, but just to get some idea, let's assume that it were to somehow collapse into a black hole. Its mass is approximately 2*1030 kg and its rotation velocity at the equator is approximately 7000 km/h. What would the diameter of the ring singularity be?
I will start with the easier question: if the black hole is a rotating uncharged black hole with mass M and angular momentum per unit mass A then the radius of the ring singularity is A/c.
The units seem to match. (The unit of angular momentum seems to be kg·m2s−1, so if we divide that by the mass and the unit of c, ie. m/s, we end up with just meters.) However, I'm having trouble understanding how the angular momentum of a rotating body is calculated.
Wikipedia cites the formula for the angular momentum of a single particle to be the cross-product of its distance from the center and its linear momentum. While this gives the angular momentum of one single point-like particle, how do you calculate the angular momentum of a(n almost) spherical object?
(Thinking about it, since angular momentum deals with vectors, and the total angular momentum of a spherical object would be sum of the angular momentums of all of its points... wouldn't they sum up to be zero?)
The issue here is that we are dealing with a singularity -- the coordinates fail at these points and, being an intrinsic singularity, means that all coordinate systems will exhibit this failure. The coordinates are not the ones that fail -- the equations of GR also fail there (they are, in fact, what causes the failure of the coordinate systems). The singularity is off-limits for GR, plain and simple.
This doesn't sound right to me. If dealing with the rotation speed of a black hole would be impossible, then wouldn't it likewise be impossible to calculate the Kerr metric in the first place, since it deals with a rotating black hole? I don't quite understand.
If we have a typical-sized star (that's large enough to collapse into a black hole) rotating at a typical speed of revolution, how fast would the resulting ring singularity rotate (in revolutions per second)?
How fast would the rotation speed be for a humongous star such as VY Canis Majoris when it finally collapses?
Also: What would the diameter of the ring be?
Suddenly I got thinking: GR predicts rotating black holes... but what exactly is rotating in such a black hole?
The singularity has zero size, so by preservation of angular momentum its rotation speed would be infinite. There's "nothing else" in the black hole to rotate. (The event horizon is not something physical. It's just a curvature of spacetime.)
But then I remembered reading that the equations predict that in a rotating black hole the singularity is actually not a point, but a ring (with a finite major radius and zero minor radius). Then I realized the answer: It's this ring singularity that rotates (at a finite speed).
Is my understanding correct?
Followup question: If the singularity is a ring, not a point, then what's the shape of the event horizon?
Sorry, but that statement is incorrect.
It covers the entire spectrum representable by a 24-bit RGB display device.
Please refer to this image about color gamut.
The larger gray shape represents the range of colors that an average human can see. The triangle represents the range of color perceptions that an RGB display can generate: much smaller than the human range of perception.
There are indeed many colors that simply cannot be reproduced by an RGB-based display. They are colors that may resemble what an RGB display can show, but are not quite the same (and, as said, it's just impossible to make the display show that exact color.) I think that examples include certain neon colors, among others.
I made better versions of those MTG cards I posted earlier, and made a few additional ones. I also explain the design rationale behind them. More to come in the future.
http://warp.povusers.org/MLP_MTG_cards/
As such, innovation and development are hindered, because for anything that you invent and create, there's a chance that you are infringing some megacompany's patent arsenal
Today's DailyWTF has an example of this. The economist William Vickrey proposed a variable fare to deal with traffic congestion problems in 1952, it was implemented for the first time for public roadways in 1995, and patented by IBM in 2008.
But this means that if I were to ever play that game, I couldn't help but to be reminded of Twilight every time she speaks... Would that be a good or a bad thing, I wonder.
We should add a special exemption to the rules that any game reviewed by the NC is automatically published without going through the voting and judging process.
To summarize: every starred movie is a top movie, but not every top movie is starred.
In other words, starred movies are not a top best movies list, like I said. They are a list of selected representatives.
(In fact, I would go so far as to say that a starred movie is not a top movie by requirement, but because good representatives usually happen to also be top-rated. I wouldn't say it's unthinkable that a more "mediocre" movie would get a star if it shows something peculiar about TASing in a very exemplary manner.)
However, because of the variety goals, not all of best movies all have a star at the same time.
Which is my point.
To exemplify: Two runs of the same game (using different goals) may be both extremely well-liked and highly rated. However, begin necessarily similar only one of them ought to have a star (if any), not both. Therefore stars do not automatically go to all the TASes that are considered best (using any measurement you want).
Could perhaps a bullet point like this (or something similar) be appropriate? (I'm suggesting this because there's a common misconception about it.)
* Starred movies are not a top list of best movies. They are a list of movies that represent what makes TASing so special. (There may of course be overlap between the two, but they are nevertheless not the same thing.)
Well frick. Both my mom and dad are gonna being watching the show soon in order to get along with their granddaughters better.
My whole family is going bonkers! And I'm not helping in the least!
The rebellious counter-cultural nature of a young man liking MLP loses its punch when your whole family likes it instead of chastising you for it and being ashamed of you? ;)
