Posts for Warp

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Posted: 2/16/2014 12:29 AM
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Warp
Banned User, Former player
Joined: 3/10/2004
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Could someone explain to the initiated what it means for a POST request to be changed to a GET request on HTTP redirection, why it's a good/bad thing, and how this change will completely destroy the WWW?
Posted: 2/15/2014 9:02 PM
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Warp
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Trying to visualize 4-dimensional spacetime in your head is extremely difficult because we can only visualize 3-dimensional space. Trying to understand curved spacetime is even harder. In an older post in this thread I think I asked if a simplified visualization that I came up with was even close to correct. Now I have another related question. I have been thinking that if the space dimensions kind of constantly move along the time axis (thus causing the side-effects that we call gravity), why is it then, that time passes at different speed at different depths of the gravity well. How is it possible that time passes slower at the surface of the Earth than at a very high altitude (such as at a geosynchronous orbit.) How can we be moving on the time axis at a different speed depending on where we are? Then I thought: If spacetime is curved, and we are moving in the time axis, does this mean that if the time axis is more curved we are moving a different distance through it than at a place where it's less curved? Like if one car starts from city A and ends up at city B, driving on a straight road, and another car also goes from A to B but driving on a curvy road, if they leave and arrive at the same time, the second car would have to had driven faster to sync with the first car. (In this case the "speed" of each car would correspond to the speed at which time passes in my analogy.) However, if that's the case, shouldn't it be the other way around than it is? In other words, if the time axis is more curved then time should go faster, not slower, than if the time axis is less curved? Am I even close to the right track here, or is this complete hogwash?
Posted: 2/15/2014 8:22 PM
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Warp
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Somehow this reminds me of a little experiment I did quite many years on a usenet forum. I wanted to create a collaboration chess game: I set up a chess game, and every day people could suggest moves and vote for moves, and the move with the most votes would then be performed. The next day it would be the same for the "other player". The intent was not to win anything, but to see what kind of game would result from this voting system. (And my purpose was to create a game that was as good as possible, ie. both "players" playing as strongly as possible, via the cooperation of many people.) It went quite well for a while, but unfortunately it ended before even the first game was even half-way through. Many people lost interest, and some other people started kind of "soft-boycotting" the entire project by suggesting and voting for deliberately bad moves in order to make it "more interesting". I didn't want one of the "players" making deliberately bad moves, so at some point I just ended the whole project. Quite a pity, really. I wonder if this idea could work here.
Posted: 2/15/2014 8:15 PM
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Warp
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amaurea wrote:
Which scientific papers are you talking about, by the way, Warp?
See for example http://arxiv.org/abs/astro-ph/0310808 (That paper itself doesn't have the misconceptions, but it's about said misconceptions, giving examples in literature and publications.)
Posted: 2/14/2014 1:32 PM
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Warp
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General relativity has some mind-boggling consequences that seem to contradict special relativity (even though they really don't.) For example, the GR equations allow (and in fact predict) for spacetime to expand and contract (so-called "metric expansion of space"). This has been pretty much confirmed to be happening to our universe, but it's also predicted to happen in other situations as well (such as close to a rotating black hole due to an effect called "frame dragging".) The metric expansion of space has the counter-intuitive result that it allows, for example, for light (or anything else, really) to travel faster than c from a distant observer's point of view (even though locally the light never travels faster than c.) This does not break the theory of relativity (but on the contrary is predicted by it.) This result is so counter-intuitive that even some scientific papers on the subject mention its impossibility (without actually fully understanding the topic.) Some such papers, for example, express incredulity about the fact that stars/galaxies that are far enough from us are receding from us faster than c. Frame dragging (another prediction of GR) is even harder to grasp. It causes for objects close to other, rotating very massive objects, to be seemingly "dragged" in the direction of the rotation. Because this is caused by the geometry of spacetime, rather than some force, there is no limit how fast (from an external point of view) the object may be dragged. In fact, the GR equations predict that there's a zone around rotating black holes where frame dragging is so strong that it causes particles to move faster than c (again, from an external POV; the particles themselves never exceed c locally, from their own POV.) This zone has been given the name "ergosphere". This in itself has some mind-boggling results. In theory if you had two rotating black holes close enough to each other, a particle could travel around them, inside both ergospheres in an 8-shaped path, that would cause it to travel back in time.
Posted: 2/14/2014 9:37 AM
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Warp
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Bobo the King wrote:
To continue the story, for much of the rest of his life, he campaigned against quantum mechanics. This is where the apocryphal (but accurate in spirit) quote, "God does not play dice with the universe," came from. What I think is even funnier is that every effort he made to poke holes in quantum mechanics just illuminated new facets of the theory. He may be second only to Niels Bohr in importance to quantum mechanics' formulation, despite his distaste (or outright disgust) with the theory.
I think this demonstrates beautifully how science works (and how it should work.) Hypotheses ought to be, and are, heavily challenged with serious, well-thought questions and objections. If the hypothesis can withstand such heavy scrutiny, and passes test after test, it's then elevated to the status of a scientific theory. Not before. (As we all are probably aware, relativity also received a lot of criticism and objections from the scientific community. It withstood the challenge and became one of the most fundamental theories of modern physics.)
Marx wrote:
Why does a large gravitional field like black hole attracts light or photon if it has no mass?
According to the general theory of relativity gravity is a side-effect of the geometry of spacetime. This geometry is affected by massive objects. An object or a particle (like a photon) that's not affected by any force will move inertially along the shortest path according to its own frame of reference. This path may look curved to us because we can only see a three-dimensional slice of spacetime. (It's somewhat similar to how parallel railroads may look like convergent in a two-dimensional photograph.) A falling object is, in fact, in inertial, ie. non-accelerating motion. An object standing on the surface of the Earth is in constant accelerating motion. (This is the exact opposite of Newtonian mechanics, and is rather counter-intuitive.)
Photon has energy and energy has mass, right?
A photon has zero rest mass, but has momentum. It's a complicated subject that I personally don't understand very well.
Posted: 2/14/2014 12:35 AM
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Warp
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Fun fact: Albert Einstein is best known for the theory of relativity. Much less known is that the concept of photons was also first invented by him. In fact, it was Einstein who first introduced the whole concept of quanta (and his Nobel prize was related to that. For some reason he was never awarded a Nobel for his theory of relativity, even though it's one of the most fundamental theories of physics today.)
Posted: 2/13/2014 7:44 PM
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Warp
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RGamma wrote:
Gravity
Gravity isn't a force, as far as we know. Light passing through a transparent solid causes it to change direction. This is caused by a really complex quantum-mechanical effect (it has something to do with the light taking all possible paths and interacting with the particles of the object, or something along those lines), but I don't know if it could be said to be caused by a force since I know next to nothing about QM. (I suppose interaction with other particles could be considered a force?)
Posted: 2/11/2014 8:20 AM
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Warp
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Bobo the King wrote:
Just as RGamma suggests, divide the above result by n to obtain (2n2 + 3n + 1)/6.
If you need to know the actual sum of all the squares in order to get their average, it pretty much defeats the original purpose for the average in the first place, which was to calculate the sum... :P It's just that for the sum of all integers that form a linear sequence (eg. all consecutive integers, or all even integers, etc.) you don't need to know the sum in order to know their average. You just take the first and the last integer in the sequence and divide their sum by 2. This, in turn, helps you calculate the sum of the entire sequence (by multiplying this average by the amount of integers in the sequence.) I was just wondering if there would be an equivalently easy way of calculating the average of a power series without having to know what the sum of the power series is (which is what we are trying to find out in the first place.)
Posted: 2/11/2014 12:01 AM
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Warp
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So is there a simple formula for calculating the average of all squares between 12 and n2 (inclusive)?
Posted: 2/10/2014 11:53 PM
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Warp
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Oh my...
Posted: 2/10/2014 10:23 PM
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Warp
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I'd say that if there is no better name for the branch, and there's only one noteworthy glitch that's being avoided in said branch, then use "no (that glitch)", but if there's a bunch of glitches being avoided, just use "low-glitch" and list the glitches in the movie's description box.
Posted: 2/10/2014 8:06 PM
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Warp
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Given the classical problem "what's the sum of all integers from 1 to 1000" (or whatever number), most people have memorized the formula that gives the answer without understanding it. I, however, like to think of the solution as: "The average of all the numbers multiplied by their amount." It's relatively easy even intuitively to understand why that gives the correct answer. The great advantage of thinking about it like that, rather than blindly memorizing a formula, is that it can be generalized to other situations as well. For example, what if the problem were "what's the sum of all even numbers from 2 to 1000?" Many people would not know how to resolve the problem, but it becomes easy when you understand that it's, again, their average multiplied by their amount. (Their average is (2+1000)/2 and their amount is 500.) The same principle can be used for "all numbers divisible by 5" or whatever. Now the problem becomes calculating the average of such a sequence. For a linear sequence it's trivial, but what about non-linear sequences? For instance, what if the problem is: "What's the sum of all n2, where n goes from 1 to 1000?" There are 1000 integers there, but what's their average? Is there a generic way of calculating the average of np (where n is a linear sequence and p is a constant)? How about other possible functions?
Posted: 2/10/2014 6:35 PM
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Warp
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Radiant wrote:
Would this be an example of what you mean? [1248] SNES Family Feud "playaround" by Heisanevilgenius in 06:46.71
Yeah. It could have a branch name like "playaround" (to indicate that it's not a speed record.)
feos wrote:
Warp, I agree with you in everything, but how do we handle naming broken-game runs and the ones that were previously considered any%? Like, glitched versus any%, by our former branching.
Could you be a bit more specific about what you mean? The fastest completion gets no branch name, and the other an appropriate name that distinguishes it from the fastest one (ie. describes in one or a few words why it's different from the fastest one.) If you want a better opinion, please give a concrete example.
Posted: 2/10/2014 5:54 PM
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Warp
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Dooty wrote:
The first time I read your comment, when you mentioned about rhythm and intonation, I undesrtood it completely wrong. (not your fault, not at all, that's why I'm feeling like that...)
Speed and pitch, basically... :) Also volume. Good speech can't be monotonous. :)
Posted: 2/10/2014 5:47 PM
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Warp
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Warp wrote:
game in time by author or: game "alternative branch" in time by author
And to add to what I said: I think it ought to be possible to have only "alternative branch" TASes, without an official WR (iow. there is no version of the TAS without a branch name in its name.) This would be the case with games for which completion speed is ill-defined or otherwise considered irrelevant.
Posted: 2/10/2014 12:10 PM
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Warp
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Ilari wrote:
Sometimes rerecord count is zeroed when it is obviously way off and the author doesn't have any idea to even approximate...
Speaking of which, some publications might need zeroing...
Posted: 2/10/2014 12:03 PM
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Warp
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Derakon wrote:
A thought: might it be worth tracking how many frames are "played" in the process of creating a TAS? Like, if the player plays 100 frames from the start of the movie, then reloads from 5 frames ago and rerecords those 5 frames, then the movie length would be 100 frames but the "total frames played" would be 105. Even more interesting would be tracking how many times each individual frame is played (i.e. the player recorded over frame 2040 a total of 50 times, etc.), so we could readily see which parts of a run caused the author the most trouble.
A graph of that would be interesting... :)
Posted: 2/10/2014 11:56 AM
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Warp
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Having skimmed through this thread once again, I'm leaning towards changing my earlier opinion (which was that it's ok to use a branch name in a descriptive manner, even for the "default" fastest completion.) (Now) I think it would a good idea to name publications in a consistent manner. In other words, either: game in time by author or: game "alternative branch" in time by author The first form would indicate the "official world record" version, ie. the fastest completion of the game by any means, within the rules of the site. The second form would be any other TAS of the same game. The branch name in quotation marks always uniquely and unambiguously defines that particular branch (such as "100%", etc.) and its presence indicates that it's not the "default" WR. (It wouldn't be impossible for an alternate branch to be actually faster than the "official WR". It just means that it uses something that disqualifies it from being the official WR, eg. starting from a savestate.) Descriptive tags ought to be limited to the movie classes.
Posted: 2/6/2014 12:34 PM
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Warp
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Tub wrote:
Also, these proofs rely on the assumption that temperature, height and wind direction and continuous. At least for height I'd just point you to the nearest cliff.
Temperature and atmospheric pressure might be better parameters. They are practically continuous (unless you want to be really nitpicky and go to the quantum level...)
Posted: 2/6/2014 8:50 AM
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Warp
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WST wrote:
Simple answer: game consoles usually cannot process float values. Thus they operate with integers, in particular, when calculating positions. For the game’s physics to be more or less realistic, those integers should represent fractions of a pixel. They are what’s called subpixels.
It has nothing to do with whether the console is capable of making floating point calculations or not. Subpixel coordinates are simply coordinates that have higher accuracy than the screen resolution. (Internally this can be achieved by either using floating point or fixed-point values.) If you are using integers, you could eg. have all your coordinates multiplied by 16 (and perform all calculations like that.) Then when you actually need the physical pixel coordinates on screen, you divide by 16. Old consoles can't draw at subpixel coordinates, but the reason to do this is that it allows better movement calculations (such as acceleration).
Posted: 2/5/2014 11:52 AM
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Warp
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Still on the subject of armchair psychoanalysis, AJ and RD are more difficult to analyze. Applejack is quite a workaholic (in a way that can sometimes go completely overboard, to the point it becomes unhealthy), and this might be at least partially caused by the fact that she has been an orphan since she was very little, and raised by her grandmother and older brother. (She may feel that she has to show her "substitute parents" that she can manage on her own.) She sometimes can feel ashamed if she can't perform at her best (eg. on a rodeo competition.) However, other than that, she seems very level-headed and sensible, with no discernible major issues. She's always friendly and almost motherly, and always ready to help those in need. She's also quite competitive, but not in any way I would see as abnormal or unhealthy. Rainbow Dash is your typical brash tomboy, but who's not ashamed of showing some femininity at times (eg. when wearing Rarity's frilly dresses). She's extremely competitive and never backs up from a challenge or duty, but can also succumb to laziness. She can break under pressure (such as the first time she had to demonstrate her talents in front of her idols), but nothing abnormal. She can be a bit insensitive at times. But as with AJ, I see no signs of hidden psychological issues or traumas.
Posted: 2/5/2014 11:38 AM
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Warp
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Thanks for the explanation. It really helped to visualize the situation. I wonder why it's so hard to intuitively accept that there are always points on opposite sides of the Earth with the exact same temperature. Much less points that have the exact same temperature and eg. atmospheric pressure at the same time.
Posted: 2/5/2014 11:27 AM
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Warp
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Tara Strong can do a multitude of very different-sounding voices, but for some reason in LC she sounds almost exactly like Twilight Sparkle. Being such a fan of MLP:FiM, it's almost surreal to play the game. I don't know if it's more amusing or disturbing... :) Man, there are so many voice samples that could be used for a Twilight fan video...
Posted: 2/4/2014 10:13 PM
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Warp
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The intuitive way of understanding why there are always points on opposite sides of the Earth with the exact same temperature (or pressure, or height) is to draw an imaginary circle (with a maximum radius) around the Earth and choose any two opposite points on that circle. One of them will (most probably) have a higher temperature than the other, ie. their difference will be non-zero. Now start moving one of the points along the circle, and the opposite point as well (so that they remain opposite) and look at the difference between the two temperatures. At some point this difference must reach zero. That's because if you move 180 degrees along the circle, you have now reversed the temperatures of the two points, ie. their difference is now the same but with the opposite sign, and thus by necessity the difference was zero at some point. (We can rightly assume that the change in temperatures along the surface of the Earth is contiguous, without jumps.) The curious thing is that you can choose any circle around the Earth, and you will find at least one point which has the same temperature as its opposite point (and probably a lot more than one.) Could someone give an intuitive explanation of how there can be two points on opposite sides of the Earth with the same two parameters (such as temperature and height)?
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