So is quantum entanglement actually FTL "communication" or is it mundane pre-determination?

Question: I have to say right off the bat, I'm a little frustrated that there seem to be very contradictory answers about this, at least to a layman like me. If two particles are entangled and you separate them by some huge distance, and you measure one of the spins, you know the other particle must be spinning the opposite direction.
The usual analogies I hear are things like, well if you have a blue and red marble, you scramble them in a bag and then take one blindly, and give the other to your friend, if you look at your marble and see blue, you know your friend must have red.
To me this sounds like "boringly classical pre-determination." Like this whole spooky action at a distance is really just "the spins were already opposite to begin with and we just separated them," as if we had a machine that spat out pairs of opposite-colored marbles and now we're surprised that they're always opposites regardless of how far apart we are when we see them.
At the same time people say it's not like that either (Bell's inequalities). In quantum mechanics the state of something is in this weird superposition where it's not known for sure -- it's sort of everything at the same time and it only takes on a particular state according to a probability distribution. So the two particle spins are unknown and yet somehow when you observe one, it "communicates" to the other (regardless of distance) what its state is so it "knows" to become to opposite.
But apparently it's not that either and there's no communication actually taking place or information passing from one to the other, and this is what really gets my goat. The usual response is that we cannot choose what the state is or input any kind of information that can come out the other end.
I feel this answer is a bit of a cop-out because it doesn't address the confusion, just sort of attacks low-hanging fruit over some semantic difference in the word "communication" even though what is really being asked is the sort of cause-effect relationship going on. I am fine with the idea that we can't directly input what we want or use it to communicate. But how is it not a form of "the particle is communicating something" or "causing" or "influencing" something to happen in the other?
Normally this discussion goes nowhere and someone inevitably says "Well you just have to learn quantum mechanics." I always find this answer deeply unsatisfying. It feels like the other person is giving up on you and can't be bothered to explain it.
So... what's going on? I'm not stupid but I'm also frustrated that these two interpretations both seem to be wrong and yet no one can actually seem to address the core point of confusion despite Googling this question across blogs, news articles, Reddit, Physics forums, Quora, etc.
It's always the same back-and-forth. "There's no communication... but it's not like the states were known to begin with either." How on earth is there a third possibility to this?
Comment: This is really the key though. It is _neither_ FTL communication, _nor_ just revealing pre-existing information. Bell's theorem says that any theory of the latter type has to be nonlocal, which is considered to be quite ugly even if it can't be used for FTL communication.
Comment: You might ask, intuitively, how could this possibly be true? After all, classically it has to be one or the other. Unfortunately the simple answer is that it has no classical explanation, because quantum mechanics just isn't the same thing as classical mechanics. I could give a nice-sounding argument using only classical intuition for what is going on here, but it would _necessarily_ be wrong because the world isn't actually classical. To get the real story, you're going to have to learn quantum mechanics.
Comment: Any correct explanation, purely at the verbal level, is going to feel like a "semantic copout" because language was invented to describe ordinary experience, i.e. classical physics. Common English simply _does not have words_ to explain what is  going on correctly, but the language of mathematics does.
Comment: (c) none of the above.
Comment: You might benefit from reading my answer here:  https://physics.stackexchange.com/a/330571/4993
Comment: Is the best explanation that it technically is a "kind" of communication or causality, just not one we can control or influence?
Comment: See this answer https://physics.stackexchange.com/questions/190670/does-the-many-worlds-interpretation-eliminate-the-spooky-action-at-a-distance-pa/190711#190711
Comment: The reason you're frustrated about this, is simply because there is no consensus in the scientific community on this topic. Physicists have been frustrated by this for as long as QM exists. The ones that are not frustrated by this are of the "shut up and calculate"-school or the "Bohr solved it all, but I can't be bothered to explain you properly now"-school. The ones that are frustrated by this come in all varieties but none of the answers they propose has been accepted as the definitive answer.
Comment: It is therefore not disingenuous to answer:"You just have to learn QM". Meaning, you'll have to find the answer for yourself.
Comment: Note that this question currently has three (out of five) closure votes, as Unclear What You're Asking. It would be beneficial if you could slim it down by making it clearer exactly what it is you're after, and cutting down on the rant and on the wall-of-text.
Comment: Slimmed it down a bit, combined paragraphs too.
Answer:
So is quantum entanglement actually FTL "communication" or is it mundane pre-determination?

In short:

It is not "mundane pre-determination".
Whether it is "actually" some form of FTL communication depends on which interpretation of quantum mechanics you prefer.
However, regardless of interpretation, if there is some form of FTL communication between the parties, then it is completely inaccessible to us.

That said, you're certainly correct in one respect: there's a lot of very poor descriptions of what entanglement is and how it works in the popular-science press. In particular, these two paragraphs do a very good job of summing up a very common misconception that arises from poorly-written material:

The usual analogies I hear are things like, well if you have a blue and red marble, you scramble them in a bag and then take one blindly, and give the other to your friend, if you look at your marble and see blue, you know your friend must have red.
To me this sounds like "boringly classical pre-determination." Like this whole spooky action at a distance is really just "the spins were already opposite to begin with and we just separated them," as if we had a machine that spat out pairs of opposite-colored marbles and now we're surprised that they're always opposites regardless of how far apart we are when we see them.

Your interpretation of that description is indeed correct. However, quantum-mechanical entanglement goes much further than that property, and this is exactly the content of Bell's theorem.
To be more precise, Bell's theorem is a description of systems that use "boringly classical pre-determination" (known in the technical lingo as Hidden-Variable Theories) to produce correlated outcomes, and it makes quantitative statements about which kinds and what amounts of correlations you can expect from such a system.
Bell's bigger argument then goes on to construct quantum-mechanical states that break those bounds, and which therefore (provably) cannot be explained with "boringly classical pre-determination" at all. And, when we talk about Bell-test experiments, we refer to experiments that implement those states and show that you do indeed get more correlations than classical pre-determination can produce.
This does raise the question about how your initial model,

you have a blue and red marble, you scramble them in a bag and then take one blindly,

fails to describe the quantum systems at play. The answer is that this classical model is unable to describe superposition states between the blue-marble and red-marble states of each bag, and for the quantum-mechanical description to work at a level where it can exceed the classical bounds on correlations, it needs to be able to measure on the superposition state
$$
|\text{blue marble}⟩ + |\text{red marble}⟩
$$
and to distinguish it from the 'conjugate' superposition state
$$
|\text{blue marble}⟩ - |\text{red marble}⟩,
$$
where that $-$ sign is a truly new, fully quantum-mechanical ontological feature that doesn't exist in classical mechanics.

OK, so it's not classical pre-determination. But is it faster-than-light communication, then?
Well... also no, this time because of another theorem of quantum mechanics - the No-Communication Theorem. This theorem states that, if you have any arbitrary entangled states linking two parties, and you allow them to perform any arbitrary physical operation on them, it is provably impossible to transmit a message in any way other than classical communication.
But that's at the level of the (ostensibly human) operators of the experiment, though. Do the particles themselves communicate?
And the answer here is that yes, it's not inconceivable that they do. More to the point, it is a consistent interpretation of quantum mechanics to suppose that there is a hidden-variable theory that underpins QM. Since Bell's theorem rules out hidden-variable theories which are 'local' and 'realist', the price for doing so is that those variables need to be 'non-local', which basically means that changes in those variables can propagate at FTL speeds.
However, the price for that is that the No-Communication Theorem requires that, to be consistent with QM, such a hidden-variable theory needs to somehow make that FTL communication completely inaccessible above the quantum-mechanical layer of the description. And that then means that, when you build those theories, they come out looking extremely contrived and artificial.
And here is where it gets subjective: most working quantum mechanicists are extremely uncomfortable with those theories as models of what reality is "really like". There are very good reasons to be uncomfortable with them, but $-$ as in all things where the interpretations of quantum mechanics are concerned $-$ this is ultimately a subjective thing.

Now as for the bulk of the text that you've written $-$

Normally this discussion goes nowhere and someone inevitably says "Well you just have to learn quantum mechanics." I always find this answer deeply unsatisfying.

Your observation is correct: this is indeed unsatisfying. But the hard truth is that, while it would be wonderful to know what's "really going on" between two entangled particles, we simply don't know. There's a broad array of proposals of how one should understand this, but they all have serious drawbacks and for each of them there's multiple reasons to think that it's completely bonkers.
We do know a lot about entanglement:

we know how to formulate the quantum-mechanical laws that define it, and which are unbeaten in their ability to match experiments
we know how to operate on those quantum-mechanical laws and the concepts within them
we know how to perform experiments that are able to probe those laws and their differences to more 'reasonable' theories
we know for sure that it goes well beyond 'classical pre-determination', and we have verified that experimentally multiple times
we also know for sure that it does not allow us, as operators, to use it for FTL communication
we also know that if it does involve some "back-end" FTL communication between the systems, then that requires additional "protective" layers in the theory that can fairly be described as completely bonkers
(but then again, every way to interpret QM does things that can fairly be described as completely bonkers)

But as to what's "really going on", we just don't know.
Judging from your text, it sounds like you already have a pretty decent understanding of the epistemology around entanglement, and that you've reached the kind of grounded frustration at the weirdness of the theory that's widely shared among working physicists. We know it's weird. We agree that it ultimately makes very little sense. We absolutely would like a better answer. We are actively searching for better answers, and we are making decent progress $-$ we are indeed advancing the state of the theory, bit by bit, and we're getting better and better at examining single quantum systems in ways that allow us to test QM in finer and finer ways. But we've yet to find that better answer.
Comment: Good stuff! I think this could serve as a canonical answer.
Comment: @user222141 That's a much bigger question than I can answer here - for now I'll limit myself to referring you to [The Talk](https://www.smbc-comics.com/comic/the-talk-3), by Scott Aaronson and Zach Weiner-Smith. If you want more details about the difference, you should ask separately.
Comment: Great answer, helps me contextualize it a bit better. As a side note, what exactly is |blue marble⟩+|red marble⟩ versus |blue marble⟩−|red marble⟩? This was the only part of the answer where I couldn't really understand the argument being made.
Comment: @user222141 : This question you ask, is exactly why I think it's right to answer back at you: "Go learn quantum mechanics". If you don't know at least the basics of the formalism, you shouldn't complain too much about not understanding it. When I was a kid, I wanted to understand relativity, and I quickly figured out that not having a solid mathematical background would get me nowhere. And relativity is still quite explainable with just words if you make an effort. But with quantum mechanics, you'll eventually have to dig deeper.
Answer: A couple of thoughts.
No, entanglement is not (does not allow for) FTL communication. With this I mean that, even if you and me share an entangled system, there is no way for me to alter what you will observe on your side. Yes, the operations I perform on my part of the system will affect what you will observe on your part, but there is no way for you to realize that this correlation exists without knowing what happened on my side as well.
In other words, there is no way for me to send you information using only our shared "entanglement link".

To me this sounds like "boringly classical pre-determination." Like this whole spooky action at a distance is really just "the spins were already opposite to begin with and we just separated them," as if we had a machine that spat out pairs of opposite-colored marbles and now we're surprised that they're always opposites regardless of how far apart we are when we see them.

The key point here is that it is possible to show (via Bell inequalities for example) that sometimes you and me can observe correlations between our observations that cannot be explained by any classical theory like the one you mention.
More Precisely, the gist is that if we denote with $x$ and $y$ our measurement choices (e.g. $x=0$ means I push button $A$, $x=1$ means I push button $B$, $y=0$ means you push button $A'$ etc.), and with $a$ and $b$ our observations (say $a=0$ means I see output $0$, $b=1$ means you observe output $1$ on your side, etc.), then quantum mechanics allows for correlations $p(ab|xy)$ that cannot be explained by any classical theory, in the sense that there is no way to write such correlations as:
$$p(ab|xy)=\sum_\lambda p_\lambda p(ab|xy,\lambda).$$
This expression means that there is no way to describe our observations by invoking some pre-existing correlation between our shared system. For example, your proposed explanation with the marbles is such a case, with $\lambda$ representing the pre-shared correlation between the colors of our marbles.
It is worth noting that the possibility of (independently) choosing different measurement settings $x,y$ is crucial in this argument. If we consider fixed, pre-determined measurements, then it is always possible to find a "classical description" of the correlations (see e.g. this post about this).

So... what's going on? I'm not stupid but I'm also frustrated that these two interpretations both seem to be wrong and yet no one can actually seem to address the core point of confusion despite Googling this question across blogs, news articles, Reddit, Physics forums, Quora, etc. It's always the same back-and-forth. "There's no communication... but it's not like the states were known to begin with either." How on earth is there a third possibility to this?

The frustration is understandable.
The way I personally like to state the apparent paradox is as follows: how can there be correlations unexplainable by a common cause, and yet that cannot be used to transmit information?.
Note that if we admit the possibility of a common cause, that is we consider "classical" situations, then it is no surprise that we can share correlations that nevertheless do not allow for communication (your marble example is again such a case).
But it's also important to realise that this is not simply some mathematical shenanigans that people like to wonder about in the abstract.
These sorts of correlations are routinely observed in the real world, and as weird as that sounds, quantum mechanics is still the best and most "natural" way we know to explain these observations.
Answer: "How on earth is there a third possibility to this?"  That is exactly the $64,000 question of entanglement, but observations show that there is indeed a third possibility.  It is possible for experiments to show correlations after the fact without it being possible to ever use this to communicate information FTL.  (And don't confuse it with the red and blue marble, look up "Bertlmann's socks" to show why that's not it.)  It means there is some kind of holistic quality of the system that maintains correlations across huge distances, yet this holistic character cannot be understood as a form of communication from one part to the other because it is maintained in ways that cannot be used to transmit information.  (Interestingly, it can be used to encode information, in such a way that to intercept that information is to prevent its transfer.  That's quantum cryptology.)
To go further, you have to start thinking about what information actually is, and where it lives.   Does it live in a system, or in someone's head?  If I read a book, is that information carried in the book and I'm just "extracting" it, or am I an active participant because I need to interpret what I read?  In the formal sense, there is less  information in a book than in a list of random letters the same length (because I would need more yes/no questions answered to be able to know the second, whereas redundancies in the first make it discernible with fewer yes/no questions), so you can see that "what is information" is tricky.
But I think this fact is telling us something:  you could have one part of a pair of entangled particles, and you could choose any way you like a direction.  You could then test the spin of your particle along that direction, and send a single bit of information (slower than light) to the other person, and with that bit tell them how to put their entangled particle into the same spin state as yours (same axis direction, same up or down state along that axis).  This holds even though you are only communicating one bit of information, yet you can choose any axis direction you like!
That sounds like communicating more than one bit, but here's the catch:  they would put their particle into the same state as yours, but never have any way of knowing what that state was!  In particular, they could never know the axis direction you chose.  This is related to the fact that when you do a spin measurement, you don't get to know what the state was, you only get to know if it is up or down along some axis chosen by you.  Plus, you only know it afterward, so much of that original information is "lost" (if it was ever really there in the first place, that's the issue of quantum information).  So the limits of what you can know, versus what "information" is in a quantum state prior to measurement, is the crux of the matter.  It's all connected to the quantum measurement paradox, and the issue of whether a wave function is a real thing that represents information we don't have complete access to in each individual case, or if it is just a rule about correlations in ensembles.  Classically, we never make a distinction between those two possibilities (like a deck of cards we just haven't looked at yet so treat as random), but quantum mechanics challenges us to decide if that distinction needs to be made.
Answer: You are worrying about the apparently nonlocal behaviour of physical systems (so called 'spooky action at a distance') that is implied from correlations calculated from the formalism of quantum theory. These were pointed out by Schroedinger and Einstein, Podolsky and Rosen in 30's. There was some disagreement but the matter was largely ignored by the most famouse physicists. There was no way to test those correlations.
In 1964 John Bell came with his revolutionary analysis of quantum theory and nonlocality
J. S. Bell, On the Einstein Podolsky Rosen paradox, Physics, 1, 195-200 (1964)
(copy here https://drchinese.com/David/Bell_Compact.pdf)
which brought a way (at least in principle) to test whether nature really behaves in such a strange way. Bell shows that quantum theory does not obey Bell's inequalities and therefore it is (in Bell's terminology) not a local theory. The inequalities provide a statistical test to decide in experiment with particle spins, whether particle spins behave in such non-local way or not.
This experiment is difficult to do and as far as I know, it was never done.
But other experiments on correlations of light, motivated by Bell's theorem, were done and are currently accepted in mainstream as a proof that nature behaves in a way that Bell called nonlocal, although the conclusion is sometimes contested (the experiments have various loopholes).
https://en.wikipedia.org/wiki/Bell_test_experiments
Also, there is some disagreement on terminology, there is another school of thought where experts prefer to say that quantum theory is still local, but not realist. Anyhow, all agree that quantum theory does not obey Bell's inequalities, which makes it very strange.
The accepted status of this question is that there can be correlations between distant systems that violate the inequalities or their analog (which is used in experiments with light), but at the same time, there is no known way to use these correlations for superluminal action at a distance or communication.
Answer: Let me give you  a simple example with a quantum mechanical particle called $π^0$.
The $π^0$ is a  neutral meson, has a specific mass $~135$MeV and spin $0$, and inevitably decays into two $γ$ (photons).
Angular momentum is a conserved quantum number so the spin of the two photons,no matter how far they may travel in the cosmos has to add up to zero. So one only has to measure the spin of one photon, to immediately know the spin of the other.
The knowledge is an association in the experimenter' head read off from the spin detection of one of the photons. The previous experiments with  $π^0$ 's  established its spin, so it is in the data bank, the previous experiments with photons established their spin, the mathematics of angular momentum is in the books, so the quantum mechanical wavefunction describing the decay process mathematically  contains the entanglement .
The decay of the  $π^0$  follows the probability distribution given by the $Ψ^*Ψ$ where the  wavefunction $Ψ$ is given by the theoretical mathematical model. The distributions which describe the decay, time, angles of decay, spin distributions between the two photons are controlled by $Ψ$ . Each individual decay has to obey the conserved angular momentum law.
It is not known what the spin of each photon will be, unless one measures it, but measuring one of them, because of angular momentum conservation, means that the other has been simultaneously measured.

So is quantum entanglement actually FTL "communication" or is it mundane pre-determination?

There is no predetermination for observables in the quantum mechanical framework where entanglement is discussed. All measurements of observables,  have a probabilistic distribution. And there is no communication except in the mathematically imposed  "knowledge" from the conservation of angular momentum.
Edit after the following comment :

@a1s2d3f4  I agree with user222141. You haven't addressed the confusion. In the last paragraph you suggest that there is simultaneously no predetermination and no communication. The OP is asking how that is possible.

It is possible because it is in the mathematics that models the data.  The only value that is communicated is the measurement  from the detector of the gamma. The rest is mathematics of the quantum mechanical model.
Example of a classical probabilistic model:
Take a rod and paint one end white and the other black and cover the ends.
Whirl it in the air and throw it. Open the end that is closer to you.
Do you need to open the other if you see your end is white, to know that the other end is black?
That is how probability enters, and the mathematics is in the  length of the rod, that tells you if you have one end the other has to be there by conservation of shape and mass.
Comment: @annav I agree with user222141.  You haven't addressed the confusion.  In the last paragraph you suggest that there is simultaneously no predetermination and no communication.  The OP is asking how that is possible.
Comment: That there is no communication, just conservation laws . like "beauty is in the eyes of the beholder" communication is in the head of the experimenter.
Comment: But if it's just mere conservation then how is this any different from "the states are already decided at the beginning / mundane predetermination"? "Communication in the head of the experimenter" is precisely the kind of definition I am speaking out against in the original post and is not what I am asking about.
Comment: In quantum mechanics states are probabilistic, as I say in my last paragraph, following the mathematics of the physics of the decay.
Comment: How does this address the point of confusion? It only seems to suggest that "You measure one, you know the other," which I am already familiar with / this isn't quite what I am asking
Comment: But the point of confusion is that despite the probabilistic nature, somehow once you observe one particle the state of the other particle becomes known as well even though both are 1. unknown quantities, and 2. separated by a very large distance where no communication is occurring
Comment: The probabilistic  nature is in the distributions of the decay times and spins. Conservation of  quantum numbers are mathematical  structures which have to be obeyed for all states in the probability distributions.
Comment: @a1s2d3f4 I edited
Answer: You need to divide entanglement in two parts -
1) Perfect Anti correlation (Bell's states) - This is what (I think) Anna v has described. This is direct consequence and instantaneous observation of conservation laws. The quantities are conserved from on set and they have to measure opposite. So you measure one and know the other.
2) Statistical correlations - These are used to disprove classical/local nature of entanglement by applying Bell's inequality to the statistical correlation percents. In my opinion, the application of Bell's inequality to statistical correlations is a faulty method. Because applying Bell's inequality requires you to assume equal likely hood of all possible outcomes, which is not necessarily true throughout the experiment.
It is pretty normal to get confused and even get frustrated if you try to scrutinize the entanglement because, all you get is religious kind of answers which can not be proved or disproved.
As far as learning quantum mechanics is considered - yes, you will be told this, so that the mathematics conditions your mind to start believing the mysterious nature.
In my opinion, the mathematics gives the correct predictions and are confirmed experimentally, but it also gives rise to superposition etc kind of non-verifiable nonsense. I have never seen a cat dead and alive ever. So, to a large extent, it is a mathematical camouflaging, which gives some correct predictions but also creates some mysteries. I think statistical correlation matching with QM predictions is a coincidence due to some classical mechanism that is yet to be discovered. The entities involved are so small that it has been very difficult to uncover the reality. Moreover once you learn the QM mathematics, you get conditioned to it and never doubt, let alone scrutinizing entanglement. You can judge it from the kind of responses to such basic questions by "partial experts" on the topic, mostly they will sing the Bell song, nothing else. The matured ones are more broad in their responses. To date, I have not heard a single "public" response that says, yes, the phenomenon/mystery needs further scrutinisation. Just watch down votes to my answer!
Comment: "Just watch down votes to my answer!" is a remarkable thing to say when you start your text with an utterly (and undebatably) incorrect statement. Bell states need not be anti-correlated - the term refers to *four* separate states, only two of which fit that description. Trying to dress yourself up in martyr robes is a nice move, but you need to get your basics right to start criticising the 'establishment'.
Comment: As for "To date, I have not heard a single "public" response that says, yes, the phenomenon/mystery needs further scrutinisation" - how many (public) grant proposals on quantum information and quantum foundations have you read recently? The fact that you don't look in the places where these things are discussed does not mean they don't happen - it just means that you're not qualified to talk about them.
Comment: @EmilioPisanty: You prove my point. I do not claim to be "qualified" to claim I understand reality. But I am qualified to raise doubts. There are two states (out of four) that fit the description. And see what point you made? If two fit the description, then those are the two I meant, is not it simple? but you have to go an extra mile to find a fault. Did I say 1, or 2, or all the Bell's states? No! I swear, I did not. I really do not even know what the hell they mean, but all I picked from pieces, is that some perfect anti correlation states are referred to as Bell's states in academia.
Comment: Comments are not for extended discussion; this conversation has been [moved to chat](https://chat.stackexchange.com/rooms/89514/discussion-on-answer-by-kpv-so-is-quantum-entanglement-actually-ftl-communicati).


Word meaning not knowing when to stop

Question: Is there a word that means "not knowing when to stop"? I haven't been able to think of one as of yet.
Answer: It does rather depend on context. Reckless will often fit, but so might unrestrained, undisciplined, careless, and several others.
Personally I think the best "single-word" answer is intemperate - having or showing a lack of self-control; immoderate. It's particularly associated with not knowing when to stop drinking alcohol, but that doesn't prevent its use in other contexts.
Note that temper has many meanings; in "intemperate" it's the verb to moderate, or tone down.
Comment: I like intemperate, that seems like what I'm going for. +1
Answer: Depending on context, you may use unrestrained or unbridled.
Answer: Incessant.
continuing without interruption; ceaseless; unending
Comment: -1: *Incessant* is normally applied to abstract things, such as **noise**, which can't meaningfully "know" anything, let alone when to stop.
Answer: Compulsive might do what you want.
Answer: Some possibilities: blithe, sense 2, "Indifferent, careless, showing a lack of concern";
uncurbed, "Unlimited; unrestricted"; gung ho, "Very enthusiastic or energetic"; high-handed, "Using power or authority without proper consideration for the feelings or rights of others"; and perhaps manic, speed demon, overboard, over the top, heavy-handed, lead-footed, roughshod, heedless.
Some facetious suggestions: unbrakeable; brakeless; brake-challenged.

Word meaning not knowing when to stop


Entity Framework 4.0 and Stored Procedures

Question: Are there any examples/articles on how to use the Entity Framework 4.0 Code First model (no edmx or xml configuration anywhere!!!) that interacts with stored procedures? Another aspect to my requirements is I am using a Repository pattern that uses an IRepository interface to abstract the actual data store (memory, database, xml, etc).  Thus, I suppose it would be a hack to expose the ObjectContext so that I can call ExecuteFunction(...) on the ObjectContext instance since the caller of IRepository can never assume it is hitting a database.  I was hoping to specify all stored procedure mapping logic in my mapping class for the entity.  The mapping class is a subclass of EntityConfiguration. Is the 4.0 CTP mature enough for this yet?
Answer: I know it's a bit late now, but here is something worthwhile looking into: Entity Framework CTP5 - How to Call Stored Procedure? and Using stored procedures with Entity Framework 4 Code First CTP5.  Did you manage with this?


How to enable EMERGENCY_PARSER in Marlin firmware?

Question: In the documentation of some commands of the Marlin firmware (like M112 - Emergency Stop), it says that the EMERGENCY_PARSER should be enabled to execute them instantaneously.
The thing is, I didn't find any information there of how to enable that EMERGENCY_PARSER or how it works.
Any help will be appreciated.
Answer: The constant EMERGENCY_PARSER is located in the advanced printer configuration file Marlin/Configuration_adv.h:

// Enable an emergency-command parser to intercept certain commands as they
// enter the serial receive buffer, so they cannot be blocked.
// Currently handles M108, M112, M410
// Does not work on boards using AT90USB (USBCON) processors!
//#define EMERGENCY_PARSER

To enable the EMERGENCY_PARSER, you need to remove the // before #define EMERGENCY_PARSER and recompile the sources.
Normally your printer will execute a command until it is ready to accept a next instruction. Without the EMERGENCY_PARSER set, the printer finishes the instruction that it is executing at the moment, if set, the execution is interrupted and immediately sent and thus not waiting for a clear space in the buffer.
Comment: Is there a way to know if `EMERGENCY_PARSER` is set without looking at the printer configuration file (for example, sending a command or checking the first responses when you connect via serial port)? Was this feature added on Marlin 1.1.0?
Comment: @fsinisi90 I don't know if you could try that out. You do need to somehow inject the `M112` in the midst of operation, usually that is done by the code as an emergency response on certain limit checks, I do not know how to insert that manually from outside.
Comment: Well, I've already tried with `M190` (wait for bed temperature) and then `M108` and it's not working, but my firmware is Marlin 1.0.3 and I guess the `EMERGENCY_PARSER` was added on 1.1.0, so I don't even have the possibility to enable it. Anyway, I was looking for a way to check it on any printer from my source code (I'm connecting through pyserial), without human intervention.


Compare increase rate over time 2 groups

Question: If you have two groups lets say Y any Z that change over "time", how do you compare if the increase rate of x and y over time is same or not. How would i set this up in R
Comment: Are these TS AR, ARMA, ARIMA, etc?  there is a function arima in the stats package that will help you set up a time series.  Here is a link to a description:.  http://stat.ethz.ch/R-manual/R-patched/library/stats/html/arima.html  You'll have to do some work on the time series like look at the ACF and PACF functions to decide what type of time series you're working with.  Building different models and looking at the $\sigma^2$ and AIC output for the model will let you know how good a model you've built (the lower the AIC the better).  AIC will be an object of the time series you build in ARIMA.
Comment: I think I need to use AR(1) or Ar(2) but both of my data Y and Z are positive linear not sideways. for example when i type plot(y~time) and plot(Z~time) the dots go from bottom left corner to top right corner. if I know this what should be my next step
Answer: A naive approach to this question, possibly a motivating example for the subject of time series, is to linearly model the effect of time in both variables, $Y$ and $Z$. If we specify that the observed outcome of these variables is so that:
\begin{array}{c}
E[Y(t)|t] = \beta_0 + \beta_1 t \\
E[Z(t)|t] = \gamma_0 + \gamma_1 t
\end{array}
you can arrange the data in a stacked (long) format with an indicator ($i$) of which variable is observed at that time with a single outcome variable, $U$.
<code>t i U
1 0 34.3
1 1 36.5
2 0 39.0
2 1 37.4
3 0 40.1
3 1 40.4
4 0 40.6
4 1 44.0
</code>
and setting up a regression model for the outcome, the growth rate can be explicitly estimated using a stratified model.
$E \left( U(t) | i, t \right) = \delta_0 + \delta_1 i + \delta_2t$
so that $\delta_1$ is the difference in means between $Y$ and $Z$ at time 0. But we have assumed the growth rate is the same between the two variables, and that is given by $\delta_2$ which is interpreted as an expected difference in outcome for a unit difference in time.
Compare that model with the saturated model with interaction terms:
$E \left( U(t) | i, t \right) = \delta_0 + \delta_1 i + \delta_2 t + \delta_3 i t$
Now $\delta_3$ is a measure of the difference in time based growth between $Z$ and $Y$. Under the null hypothesis $\delta_3=0$ because there is no difference in growth rate over time. By testing this hypothesis using the stratified (nested) model using a likelihood ratio test, you have a simple, naive approach to testing whether there is a difference in growth rates.


Loan from NRI Brother

Question: If I borrow money (10 Cr approx without Interest) from my brother who is working in abroad is it taxable to IT of India for my brother ? does that amount count as my income, and should I have to pay tax on it? Should I have some mandatory paperwork?
Answer: Income earned outside India by NRIs is not taxable in India. When your brother transfers money from abroad to your account in India, he should create appropriate documentation (in duplicate) that this is a loan to you, sign both copies, and send both copies to you. Sign both copies yourself and send one copy back to him. Thus, you both have proof that this is a loan in case the income tax authorities in either country have any questions.  If and when you pay the loan back, get a receipt from your brother acknowledging that the loan has been discharged. If you don't do all this, the money would be regarded as a gift from your brother to you. If I remember correctly, gifts between near relatives do not incur gift tax, nor are they taxable income to the recipient. So, whether this applies to you is something for you to determine.  It is common in India to refer to a very distant cousin as a brother (sometimes cousin-brother is used), whereas the gift tax rules are are very specific as to who are considered to be near relatives for the purposes of gift tax.

Loan from NRI Brother


Dragging files into blender

Question: Is there away to click and drag an STL file from a folder or my desktop to Blender? or do I have to use the old fashion way file-import?
Answer: Just the good old fashioned import I'm afraid. If you have a lot of STL's, I believe you can batch import them via. Python scripting. I have found this thread, this however is OBJ's and on Mac, but perhaps it cna point you in the right direction:-)
Drag and drop importing of .OBJ files
Answer: Good to note : drag'n'drop operations are being worked for Blender 2.8. .blend files can be managed that way already.
For importing files, I guess this will take more time since each file type have its own addon, and in order to be able to drag'n'drop such files you need to make some choices concerning the import settings being used or prompt an import dialogue window to let the user chose his jam.
Comment: "drag'n'drop operations are being worked for Blender 2.8"

Do you know more on this? Will add-on makers be able to create their own drag-drop operations for specific file types?

Dragging files into blender


ActionStatus only affects a single PageBlockButton, not both

Question: While testing a page I was working on, I noticed something strange- the apex:actionStatus I had set up to prevent users from clicking save more than once was only working with the button that the user clicked, but not the other button on the page.
This second button is generated by Salesforce by the attribute location="both" in my apex:pageBlockButtons tag.
My assumption is that since my actionStatus is contained inside the apex:pageBlockButtons tag, that the status would be duplicated by the process which creates the second button, allowing both of the buttons to be affected by the same ajax process. The gif below shows that this is not the case.

What changes could I make to my markup to share this single actionStatus across two buttons?

Example page which replicates this behavior:
<apex:page standardController="Account">
    <apex:form>
        <apex:pageBlock title="Account Edit" mode="edit" id="accountPanel">
                <apex:pageMessages />
                <apex:pageBlockButtons location="both">
                    <apex:actionStatus id="asyncStatus">
                        <apex:facet name="stop">
                            <apex:outputPanel id="stop_panel">
                                <apex:commandButton action="{!Save}" value="Save" rerender="accountPanel" status="asyncStatus" />
                            </apex:outputPanel>
                        </apex:facet>
                        <apex:facet name="start">
                            <apex:outputPanel id="start_panel">
                                <apex:commandButton value="Working..." disabled="true" />
                            </apex:outputPanel>
                        </apex:facet>
                    </apex:actionStatus>
                </apex:pageblockbuttons>
        </apex:pageBlock>
    </apex:form>
</apex:page>

By changing the generated status value of the event json generated by Salesforce, from 'status':'j_id0:j_id1:accountPanel:j_id28:bottom:asyncStatus' to 'status':'j_id0:j_id1:accountPanel:j_id28:asyncStatus', I am able to get the top and bottoms panels in sync, but only when clicking the bottom button, and these changes are removed once the page rerenders. It looks like I'll need to modify a lot more of the generated mark-up to get this to work, but I'm still looking for anyone who might have noticed this before.
<input class="btn" id="j_id0:j_id1:accountPanel:j_id28:j_id29" name="j_id0:j_id1:accountPanel:j_id28:j_id29" onclick="A4J.AJAX.Submit('j_id0:j_id1',event,{'similarityGroupingId':'j_id0:j_id1:accountPanel:j_id28:j_id29','parameters':{'j_id0:j_id1:accountPanel:j_id28:j_id29':'j_id0:j_id1:accountPanel:j_id28:j_id29'} ,'status':'j_id0:j_id1:accountPanel:j_id28:bottom:asyncStatus'} );return false;" value="Save" type="button">

Comment: An easy work around to this is to have a js "onclick" function that disables all buttons. When re-rendered, those buttons are enabled.
Answer: Add pageblock buttons like
<apex:PageBlockButtons  location="top/bottom/both">


Can I set Tx power too high?

Question: I have a high power WiFi card (AWUS036NH) which is capable of tx powers as high as 33 dB.
Recently I've, ehm, accidentally, changed the corresponding regulatory domain to allow up to 40 dB.
Now when I bring the interface up, iwconfig claims that tx power is 40 dB which is impossible.
So my question is this: What is the real tx power when it says 40 dB? Does it actually try to transmit at 40 dB or does it go to max (33 dB) power? Or does it module the power (in this case by 34 resulting in 6 dB) or something completely else?
And most importantly: Can this damage the card?
Obviously I could set the regulatory domain to max of 33 dB and fix this but I have other wireless cards with lower output (namely AWUS036H and TL-WN722N) which also go to the max power allowed by the regulatory domain.
And if this is an issue, how do I fix it? I've tried adding up iwconfig wlan0 txpower 33 or wireless-txpower 33 to /etc/network/interfaces in the wlan0 section but the interface still starts at 40 dB.
Answer: Any changes to force the hardware to operate upper than the normal levels can damage or at less reduce the hardware's time life.
One good question is if the OS is really setting AND recognizing the tx power according the config\results.
Comment: > One good question is if the OS is really setting AND recognizing the tx power according the config\results.
Yes, that's pretty much the question I'm asking.

Can I set Tx power too high?


Particle system converted to objects keeps multiplying when i try to join them using ctrl j

Question: i made a hair particle system and then made real instances of it. Then when i try to join them using ctrl j the whole thing changes and the same objects gets multiplied many times. pls help
I'm using blender 3.3
Answer: All instances share the same mesh data after converting. When you perform the join operation this mesh data changes - it becomes consisting of all meshes you have joined. But as soon as all objects initially used in the particle system continue sharing the same mesh data - which now is the joined mesh - each of them starts to look like multiplied mesh.
To avoid it, before joining meshes, first go to the Object Data Properties tab (green triangle icon in the bottom right panel) and press a digit near the object data name. This digit determines how many objects in the project share the same mesh data-block. By pressing it you make a copy of the mesh data block of the active object and assign this newly created mesh to this object. This way the active object starts using its individual mesh data-block and you can join other meshes to it without affecting other objects which used the same mesh data-block.
You don't have to make individual data blocks for each object you are joining, only for the active one.


Mobile view doesn't load the edit summary

Question: This bug's simple and short to explain. In mobile view:

Submit an edit on a post. Provide an edit summary for your edit.
Return to edit that post further within the grace period.

What should happen: The edit summary should be prefilled with the one you just provided, like on the regular site view.
What happens: The edit summary will be blank.
(That's it, that's the entirety of the bug.)
This leads to an additional quirk
As for what your edit summary will actually wind up as in the revision history, something different happens depending on whether you filled out an edit summary in mobile view or not:

If you submit any edit summary at all, it will overwrite your previous one.
If you leave it blank, an autogenerated edit summary will be appended to the current edit summary of that revision. This will repeat indefinitely for each edit within the same revision. Here's an example of this in action.
Answer: This has been fixed and will be deployed in the next build (rev 2253 on meta and  rev 1611 on the network).


How can I stop a porch crack from causing internal cracking?

Question: My front porch slab has cracked and part is at least an inch lower. It is supporting the roof. Now there is a crack going up the inside of my drywall at the same place. Suggestions on how to solve this so I make sure it is done right.
Comment: Pictures or drawings would help. Do you know for a fact that the porch isn't going to sink further or heave back up at a later date?
Comment: Nothing in the post indicates the movement has stopped, in fact it probably will continue. Heave or sink depending on moisture and/or temperature. Support the roof as @DMoore suggests, then hire a foundation contractor who will probably recommend excavation and stabilization with a concrete footing or grade beam.
Comment: well first get the post jacked up to the appropriate level and add shims underneath.  This may in fact be all that you need to do given that the porch isn't sinking anymore.
Comment: Part of the solution is understanding if it's still moving.  How old is the house/porch/this problem?  Do you live in an area that freezes?  Expansive soils?  Have you noticed if the crack opens & closes seasonally?  Jacking & shimming the roof may work if it never moves again, but that's unlikely.
Answer: You have to jack the porch up to get it back to the correct height.  I would suggest using a level to hold at a congruent part of your roofline or front molding.
Take a car jack and a 4x4 and prop the roofline until it is a bit higher (1/8") than level.  Slide under some pressure treated wood or rubber shims under the posts.  Check in local rafters, connecting pieces and make sure that everything is snug, braces are still work, and so on.  You need a really good visual inspection.  This is a bit of an emergency since if you wait you could incur a lot of damage.
Now for the porch... There are a TON of ways to go about this.  You could just leave it alone and hope it doesn't sink anymore.  They won't sink forever even with bad footings.  There comes a point where they pretty much stay.  Just make sure the dirt around it isn't eroding - if it is landscape to protect the area.
You could also have a new porch poured.  They would simply jack up your posts, demo old porch, and pour new.
You could build a wooden porch over old.  This would probably require a little demo for the posts.  This is only feasible if your porch is a bit lower than your step - or you have to do a total demo.  Demo isn't as hard as you think because you can dig a hole and bury most of it in most cases.
People do have their pads injected with concrete to provide makeshift footings.  Concrete company will come out, drill through porch in strategic areas, bore deep enough for footing, and pour.  The good companies that do this have it down to a science and do great long lasting work.  However most never give you a proper footing and it sinks again in 5-10 years.
Really the take away is get it jacked up and then figure it out after.  This happens all the time and isn't the end of the world unless you let it go.
Comment: @TylerDurden - What is your assessment?  Burn house down, demo concrete and start over?  You make absolutely no sense.  You know that most footings in most areas aren't 6 feet deep right?  Also the user made no remarks about their location.  This would be crucial information that you would need to make your remarks but you haven't asked.
Comment: More info on slab jacking.  I've seen it done twice - once has held up well going on 10 years now I think.  The other didn't, but the civil engineer told them it probably wouldn't - cost difference was enough to give it a try anyway.
http://www.concretenetwork.com/concrete/slab_jacking/what_is_slab_jacking.htm
Comment: You can believe this rosy optimistic assessment... or reality.
Answer: Forget the porch, it is a goner. The important thing is to support the roof.
You need to create a footing for the pillar (or pillars) that is/are holding up the roof. Dig 6 feet down minimum make a bed of gravel. Insert a concrete pillar form (you can get them at Home Depot). Pour concrete into form. The footing should be 6 feet or more under the surface of the earth. Put the pillar on top of this footing.
A larger issue is the rest of the house. If the whole house is on a "slab", meaning it has no foundation and no footings, you are pretty much screwed because the same thing will happen to the house as happened to your porch. In that case, basically the house is a raft, not a house. Once the "slab" of the house cracks, water will infiltrate and the nightmare will begin.
Note that there are "crack specialists" who cater to the cracked slab business by injecting stuff into cracks. Its pretty much snake oil, although if you are selling your house it can be useful to disguise the unsound condition of the foundations, but a good home inspector will not be fooled.
You can do all kinds of half measures, but all of these fixes will not work, because the essential problem is that the ground is shifting underneath your foundation. You can inject goo and concrete all day long and as soon as the subsidence repeats the next winter or whatever it will crack again. Whether the cause is sliding clay, sand, frost heaves or whatever, if you just put stuff on top of it, it will crack. To make a sound foundation you have to go DOWN until you reach a stable stratum.
Comment: Lots of assumptions leading to conclusions here... I think the OP needs to come back and clarify some things before we can decide anything. FWIW, plenty of slab on grade houses have footings, thus they are not "rafts".
Comment: @AloysiusDefenestrate If the porch is cracking and he has a slab, then it is very likely the slab will crack too. What, do you think the soil under the porch is bad, but magically the soil under the slab is good??? Whatever the cause of the subsidence is, it will affect the whole house, not just the porch. The porch is just the first to go, the canary in the coal mine, so to speak.


In Oracle SQL, why are the deleted (uncommitted) rows not visible in current session but visible in other sessions?

Question: When a DELETE query is executed, from where exactly is the data deleted? Why is the data still visible in other sessions? What are the background processes that are carried out when a DELETE query is fired in Oracle SQL (at architecture level)?
Comment: That's how transactions work: http://en.wikipedia.org/wiki/Database_transaction and of course the Orale reference: http://docs.oracle.com/cd/E11882_01/server.112/e25789/transact.htm
Answer: You may want to familiarize yourself with ACID - specifically, Isolation.  If you want it to be visible to other sessions, be sure to do a commit after the delete.
The data is still visible in the other session by design, due to the standards linked above.
Answer: As well as the discussion of ACID properties to which ziesemer referred you, you should know about Multi-Version Concurrency Control or MVCC.  If you want to know 'all about it', consider reading Concurrency Control and Recovery in Database Systems by Philip A. Bernstein, Vassos Hadzilacos, Nathan Goodman (available for download).
In Oracle and other similar MVCC DBMS, when you start a transaction, a note is kept of a timestamp which identifies that start time (but the timestamp value is not necessarily a simple 'seconds since the Unix Epoch' value).  While that transaction is running, it will not see any data inserted with a timestamp after its start time.  The system keeps previous versions of the data pages available for transactions that are still running.  When the transaction writes a page, it creates a new copy with a new timestamp, but that copy is not made available to other transactions until the modifying transaction commits, and even then, it is only made available to transactions that start after the commit.
Answer: the row is deleted for the local session as soon as the command is issued, but not for other sessions until COMMIT.


What are "disputed" flags?

Question: Most of my flags have been marked as "helpful" A few of them have been marked as "declined", and the help pages clearly explain that a moderator has looked at such flags and determined that they should not be acted on. But a few are marked as "disputed". I have not found many description of what this means in the help pages, or anywhere. Just what does it mean when a flag is disputed?
Answer: When asking about the Stack Exchange system, it's usually best to look first on the site dedicated to that purpose.
Simple keyword searches are often enough, for example, "disputed flag" gives this Q&A as the first result.

A disputed flag is whenever your flag was dismissed as neither helpful nor declined, or that your flag was reviewed but no conclusive action was taken. This is intended for use in cases where the validity of a flag is ambiguous.
Currently, the following scenarios result in a flag being disputed:

An active spam or "rude or abusive" flag was cleared (but not declined) by a moderator. These flags are unique in that marking them as helpful can impose lasting penalties on the post and its author, so a special mechanism is provided for borderline flags to be cleared without penalizing the author or the flagger. This can also be done retroactively on already-dismissed flags, if a moderator clears all such flags on the post (both active and dismissed flags).

A "not an answer" or "very low quality" flag was active on the post while it was being reviewed the Low Quality Posts review queue, and the final result of the review was "Looks OK".

[Some additional Stack Overflow-only causes are not applicable here and left out of quote]
Disputed flags are considered neither helpful nor declined, regardless of the action taken in response to them. They do not affect a user's daily flag count and don't count toward flag bans.
Note that in most cases, moderators cannot manually mark a flag as disputed (except in the above first case of clearing spam or "rude or abusive" flags), so borderline flags that are manually reviewed by a moderator will generally be marked helpful or declined per the moderator's discretion.
See also: What is the difference between disputed and declined flags?

The link in the original last paragraph is also likely to be informative, if the difference specifically between declined and disputed remains unclear.

What are "disputed" flags?


How to start building DApps

Question: Hello guys I am a beginner trying to learn how to build DApps and i have knowledge about ethereum and bitcoin i know how both of these work i wanted to get my hands dirty with how to start building DApps i have experience with Django(python framework to build full stack websites) and have a basic knowledge about React can someone please tell me what is the tech stack required for building DApps and if i need to learn other technologies like expressjs and nodejs or i can just use react and solidity to build fully functional DApps
Thank you
Answer: To start building DApps, first, choose a blockchain like Ethereum or Polygon. Then, learn Solidity, the language for smart contracts. Next, pick a front-end framework such as React, Vue, or Angular to create your user interface. Use Web3.js or Ethers.js to connect your app to the blockchain. Explore options for oracles, storage, and authentication to add more features. Check out these resources to get started:
Blockchain Selection:

Ethereum - https://ethereum.org/
Polygon - https://polygon.technology/developers

Solidity Mastery:

Solidity docs - https://docs.soliditylang.org/en/v0.8.17/

Front-end Frameworks:

React: https://reactjs.org/
Vue: https://vuejs.org/
Angular: https://angular.io/guide/quickstart

Blockchain Interaction:

Web3.js: https://web3js.readthedocs.io/
Ethers.js: https://docs.ethers.io/v5/

Platforms:

OpenZeppelin: A widely-used library for secure smart contract development and deployment.
CryptoZombies: An interactive platform for learning blockchain development through building simple games.
Learn Blockchain, Solidity, and Full Stack Web3 Development with JavaScript – 32-Hour Course

Commence with small projects, experiment, and continue learning!

How to start building DApps


Multicollinearity Problem

Question: Is there a way to determine which variable has more influence on dependent variable when your variables are highly correlated between themselves ?
Most of the ways which deals with multicollinearity helps to improve prediction, like dropping variables who have high Variance inflation factor or combining variables who have high collinearity into single predictor, but they do not answer question which variable is more important.
Comment: My approach is to iteratively bootstrap or jacknife a series of random samples, first pruning out those variables that are highly nonsignificant. Once the remaining set of variables has more or less stabilized at a p-value around p<=.15 or less, I focus on the issues wrt collinearity. The VIFs and eigenvalue indexes are good metrics at this point. By identifying variables (typically in pairs) that are collinear, prune away that variable with a lower t-value and is wrong-signed based on comparison of the parameter with a pairwise correlation. Eventually, a stable and noncollinear set emerges.
Comment: The broader category your question falls into is variable-selection or feature-selection. There are multiple approaches to this type of problem.
Answer: Assuming you're doing OLS ($Y=X\beta_{ols}+\epsilon$), here's one approach using principal component analysis (PCA) that may provide some insight:
1) Demean and divide each of your independent variables by their standard deviation - this will allow easier interpretation later on.
2) Perform PCA on your $k$ number of independent variables, with $n$ observations. This will decompose them into scores, an $n$ by $k$ matrix $S$, and a $k$ by $k$ square transformation matrix $T$:
$$
X=ST
$$
The scores have the property that each column is completely uncorrelated with every other column, so that $cor(s_j,s_i)=0$ for all values of $j$ and $i$, and the transformation matrix $T$ will have the property of being invertable. Furthermore, the first column of $S$, lets say $s_1$, will be the most important in terms of explaining the commonalities between columns of $X$ (this is because the first column is associated with the largest eigenvalue).
3) Estimate your model using the scores:
$$
Y=S\beta_{pca}+\epsilon
$$
The coefficients are not immediately interpretable, so next is where the trick comes in.
4) Look at the $j^{th}$ column of $T^{-1}$ corresponding to the $\beta_{pca,j}$ with largest t-statistic - this will tell you what relationships within $X$ are most important. The reason is made clear after re-writing identities above:
$$
\hat{Y}=X\beta_{ols}=(S)\beta_{pca}=(XT^{-1})\beta_{pca}$$so$$ \beta_{ols}=T^{-1}\beta_{pca}
$$
Because of the first step, the magnitudes of the elements in $T^{-1}$ are directly comparable, and each column denotes a linear combination of your $X$s. You're interested in what linear combinations are most relevant, so that, for example, if one variable is the most important, the $j^{th}$ column of $T^{-1}$ will have a an element in it much larger than the rest of the elements, and will correspond to the "most important" variable in $X$.
Comment: I have one question. In step 3 what I need is to look for the best model with these scores ?
Comment: For model selection, you're right that you don't need to go beyond step 3. Because the columns are orthogonal, if all the p-values on $\beta_{pca}$ are significant, then all of the variables included in the pca significantly contribute predictive power. If there is at least one p-value that is not significant, then you should consider a different set of variables (a subset of the original), perhaps with different transformations (e.g. spreads) - however, there is no way, by just looking at the p-values, to determine which variables in $X$ are not contributing in this case.

Multicollinearity Problem


What's the difference between WPA and WPA2?

Question: What are the biggest differences between WPA and WPA2 and why is AES so much safer than TKIP?
Comment: Since this is clearly in reference to 802.11, how is this above L4?
Comment: Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer.
Answer: WPA and WPA2 in very simple terms are two different methods for and end device and AP to exchange encryption keys. Depending on your platform, you can support WPA and/or WPA2 with either TKIP or AES.
TKIP and AES are the two methods by which the data is encrypted.

What are the biggest differences between WPA and WPA2 and why is AES so much safer than TKIP?

If it helps, think of the difference as pressing a paper towel to a three inch gash on your arm versus getting stitches at the emergency room. One is an immediate solution that mitigates the problem at hand, the other is a better, longer term solution.
WEP was broken (badly) and needed to be fixed. However standards bodies sometimes move much slower than solutions are needed. So WPA/TKIP was provided as a better solution than WEP that could be implemented purely in code/software/drivers.
Basically, TKIP is WEP with a few extra features, provided to the community largely by a major network vendor they had previously developed as proprietary enhancements. While it provided fixes to many of the problems with WEP, it is still based on WEP.
WPA was derived from a draft of the 802.11i amendment from the IEEE. There were some changes from the draft to the finalized version of 802.11i, which is why the 802.11i standard version is called WPA2. Ultimately the differences are relatively trivial in the grand scheme of things.
For encryption, the IEEE selected AES for 802.11i. This was a much stronger encryption than WEP however many existing wireless devices were not capable of handling the demands of AES, often requiring new wireless adapters to be installed/used.
Because of this limitation to AES, it was allowed to run either WPA/WPA2 with TKIP instead of AES until the IEEE finalized 802.11n. 802.11n no longer allowed support for TKIP, so an access point was supposed to disable the HT (high throughput) data rates if it were used and operate like an 802.11a/g device.
Since that time, only WPA/AES or WPA2/AES are supported officially by the 802.11 standards.


What is the meaning of the title Trinity Seven?

Question: I understand why Trinity Seven because there are seven deadly sins represented by a girl which is needed to be controlled by Arata. But I don't understand why Trinity? Which is referred to as the Trinity? Does Arata's magic have three forms? Does he need to do three things to control these seven sins? Are there three magus who can control these seven sins? What does the Trinity represent?
Answer: This is what I currently know about the term Trinity Seven and Trinity in the context of this manga.
The accuracy of this post depends largely on the fan translation of the manga series.
When writing this answer, I confirmed all the facts by checking back on the manga. However, I didn't check out the whole series from start to end. I only picked out the chapters which I remembered to have the relevant content and cited from it.
Trinity Seven
Trinity Seven refers to the 7 strongest mage in a world (there can be many parallel worlds).
In Arata's world, the Trinity Seven are the 7 girls: Asami Lilith, Kannazuki Arin, Kazama Levi, Yamana Mira, Fudou Akio, Kurata Yui and Lieselotte Sherlock.
According to Liese in chapter 17, to be a member of the Trinity Seven means that

 one has acquired the Lost Technica in one's archive. In Liese's case, it was "Last Crest".

As explained in chapter 36 of the manga, the magic king is closely related to the Trinity Seven. Below is the summarized definition, based on  the fan translation by VISCANS:

 There exists an infinite number of worlds, with each world connecting to each other by causality. Worlds begin and end, are born and destroyed over and over again. Magic king exists for such system, and his mission, his fate is to reduce his world to nothingness. A magic king is born human, a baby with the secret of unlimited magic power. Regardless of the circumstances of the magic king, he will encounter the Trinity Seven and begin his transformation into a proper magic king.

Trinity
In chapter 36 of the manga,

 ... after Arata copied Lieselotte's Logos Arts in Acedia archive, along with Lilith's Outer Alchemy in Luxuria archive and Akio's Matra Enchantment in Gula archive, he was confirmed by the sword Judecca to have attained Trinity.

However, the condition for Trinity is quite ambiguous. At the beginning of chapter 35,

 ... Arata found the Black Imperial Sword Judecca. The sword identified Arata's Magic King element and confirmed his Superbia archive and Impero thema, then it went on to recognize Outer Alchemy in Luxuria archive and Matra Enchantment in Gula archive. However, the sword concluded that Arata did not meet the Trinity requirement, and it started to initiate Magic King Berserk Mode.

It was quite clear from chapter 5 of the manga that there are many thema (research topic) in an archive. From my personal impression, it seems that different mages working on the same thema may study and master different magics.

 And along that line of reasoning, I speculate that Arata had yet to come up with or mastered any magic under Imperium thema, so it was not counted towards the Trinity requirement.

Apart from the likely direction of Arata eventually copying the magic from all members of Trinity Seven, and thus in control of magics from all 7 archives named after the 7 deadly sins, it is not clear how the Trinity requirement works. We know "trinity", from Christian doctrine, has tri- meaning three in it. However, it is not clear three of what (archive alone is incorrect, as seen above), and whether it requires the mage to have certain level of mastery.
To make the matter more confusing, according to chapter 37 of the manga,

 Arata attained power of a Trinity when Akio, Liese and Arata himself connected to their archives.

And at the end of the chapter,

 Abyss Trinity, Lilith's father and antagonist in the arc, was surprised by the fact that Arata exceeded Trinity after Lilith reconnected to her archive, which means Arata had 4 archives executed at the same time.

So there seems to be a further distinction between achieving the Trinity status and actually performing magic in Trinity mode.
Answer: The Trinity might refer to the mastery of three thema because in episode 10 of the anime, we see Hijiri using a mode ,which is in a way, similar to Arata's Astral Trinity form. Hijiri says that this form is stronger than Magus Mode and she also adds that this is the quintessence of her archive and is the result of her mastering three thema proper to the Ira archive. However in the film Heavens library & Crimson Lord, Lilith is said to possess the quintessence of Luxuria archive in her body without achieving Trinity through the mastery of three thema.
But for Arata, the Trinity form is more difficult to achieve because he has some some conditions to clear in order to do that. Still in the film Heavens Library, Liese explains that there is three conditions to fulfill if Arata wants to copy another magic or thema coming from Archives other than his own :
-First condition: he needs to understand what is the magic he is using (the name) and how it must be activated.
-Second condition : he needs to know the origin and the creator of the magic
-Third condition : he needs to decompose the magic
Arata already achieved Trinity in the whole sense of the term when he used Mentra Enchanted from the Gula Archive. This means the conditions are different for candidates and Demon Lord or it depends on the Archive they chose or Arata did not use conventional means to achieve Trinity. Judging by the actions of Judecca in chapter 35, it seems Arata must master three themas from three differents Archives excluding Superbia which leads to : Gula Archive : Fides, Acedia Archive: Stagna , Luxuria Archive: Abies needed for Arata to be recognized by Judecca. In Heavens Library, a clue may be introduced to us as to why Judecca wanted him to go berserk when Arata says he controls 4 four archives and four themas. Mastering and Controlling are two differents things, one is achieved through efforts and the  other through sheer force.
This leeds me to believe that Arata will be different from the other Demon Lords by the theme he chosed. The other Demon Lords always wanted to destroy the world even Abyss Trinity even though he went against his own Archive to give birth to Lilith, he still followed the mission given to the Demon Lords which was to destroy the world for it to be reborn. Arata chose to follow another route and decided to control the world to stop its destruction in other words went against his mission.


Why would you do a password audit

Question: I was thinking last night after reading an article about pen testing and security audits, why would you get a list of all the passwords for the company you are auditing and put them through a piece of software to analyse ?
Comment: Well, I would guess these are password hashes...
Comment: "why would you get a list of all the passwords" - You would not do this.
Comment: well maybe not all of them a snippet
Answer: You wouldn't get a list of all the passwords.  Any company that could or would produce such a thing would fail any reasonable security audit.
You might get a list of all the password hashes which could then be run through a tool that attempts to determine what the password is.  The ease with which the password hashes can be broken and the types of passwords that are broken will be a good guide to figuring out what password complexity policies need to be addressed.  If, for example, you're able to crack half of the password hashes because users are entering 6 character passwords that use all lower case letters, then you'd probably recommend increasing the minimum length and imposing some requirements about the use of uppercase letters, numbers, punctuation and other characters.
Comment: Though it is a bad idea, there is always the suggestion to increase complexity. See why this is wrong: http://xkcd.com/936/
Comment: @ms4py - Sure, there are different ways to craft the rules to ensure the passwords are complex enough.  If you require 20 character passwords, for example, you probably don't care about whether the password is in all lower case.  Then there is the matter of training your users to generate and remember 4 random common words or to pick the first character from each word in a long phrase.  Password complexity rules aren't perfect, but they do at least prevent users from using "password" or "password1" as their password.
Answer: To test for potentially weak passwords that can be cracked easily by a malicious attacker.
This could give an indication of the state of the password policy of the particular company, which might be an issue in certain circumstances.
If there are plenty of weak passwords found, the pen tester could suggest to the company to change and enforce a better password policy.
Of course, i see no reason to ask the company to hand over a list of passwords. Perhaps it could be a list of passwords found after compromising a user database, or a linux shadow file.
Answer: If you do this from the same ip number and for root account and you have firewall switch off and sshd started up - this is definitely dangerous :-)
ps. Passwords should not be used in plain text, it should be stored only in the memory of users. Dealing with lists of user passwords would be seriously no good.
The best is to enforce a nice policy on password change and expire them, so after users will be asked to change the password, so then you will know that it's all fine and the passwords are strong. And they should be stored as salted hash, preferably 100.000 times hashed.

Why would you do a password audit


"I found that, on average, there are...." or "I found, on average, that there are..."?

Question: So if you couldn't figure out the question from the title, does the subordinating conjunction (the word "that") precede or succeed the extra information between the commas?
Answer: The first version is the correct one. On average relates to the information you found out, not to your finding it.
Comment: I think the principle here can be clearly illustrated with something like *He knew **that tomorrow** he would die* - where if we move the word ***that*** to after "adverbial" ***tomorrow***, we end up with something that's clearly nonsense: *He knew **tomorrow that** he would die*. But in OP's exact context it's not that obvious to me that every native speaker would particularly notice and/or interpret the two versions differently. And that's even more the case if we replace ***on average*** by, say, ***obviously*** (in which case both versions mean "more or less" the same to me).
Comment: Yes, I agree that many native speakers might not notice.
Comment: Actually, I think there are potentially ***three*** possible parsings for such constructions, even if they net down to only one or two possible *meanings*. The flexibly interpreted adverbial element might attach to the verb in the "lead-in clause" *(I found, He knew)* or to the following "that-clause", but it could ALSO sometimes be seen as a "whole sentence adverb". Which in practice would normally carry one or other of the previous two senses, but I'm guessing you could contrive examples where it really does have a third meaning.


Keep getting permissions error gcloud.container.clusters.get-credentials

Question: I am trying to integrate CircleCi with gcloud Kubernetes engine.

I created a service account with Kubernetes Engine Developer and Storage Admin roles.
Created CircleCi yaml file and configured CI.

Part of my yaml file includes:
docker:
            - image: google/cloud-sdk
        environment:
            - PROJECT_NAME: 'my-project'
            - GOOGLE_PROJECT_ID: 'my-project-112233'
            - GOOGLE_COMPUTE_ZONE: 'us-central1-a'
            - GOOGLE_CLUSTER_NAME: 'my-project-bed'
        steps:
            - checkout
            - run:
                  name: Setup Google Cloud SDK
                  command: |
                      apt-get install -qq -y gettext
                      echo $GCLOUD_SERVICE_KEY > ${HOME}/gcloud-service-key.json
                      gcloud auth activate-service-account --key-file=${HOME}/gcloud-service-key.json
                      gcloud --quiet config set project ${GOOGLE_PROJECT_ID}
                      gcloud --quiet config set compute/zone ${GOOGLE_COMPUTE_ZONE}
                      gcloud --quiet container clusters get-credentials ${GOOGLE_CLUSTER_NAME}

Everything runs perfectly except that the last command:
gcloud --quiet container clusters get-credentials ${GOOGLE_CLUSTER_NAME}

It keeps failing with the error:
ERROR: (gcloud.container.clusters.get-credentials) ResponseError: code=403, message=Required "container.clusters.get" permission(s) for "projects/my-project-112233/zones/us-central1-a/clusters/my-project-bed". See https://cloud.google.com/kubernetes-engine/docs/troubleshooting#gke_service_account_deleted for more info.

I tried to give the ci account the role of project owner but I still got that error.
I tried to disable and re-enable the Kubernetes Service but it didn't help.
Any idea how to solve this? I am trying to solve it for 4 days...
Answer: I removed the service account and recreated it (with same name and roles). Generated a new key and updated the CI and suddenly it worked. gcloud glitch.


Winter Watering time of day? At what temperature do I cover any of the plants with plastic tarp?

Question: I have a garden in san mateo, ca that is only 5x9 and we have 5 large tomato plants, herbs, broccoli and lettuce.  We have an automatic water sprinkler that goes off every other day.  I want to know if I should arrange the time of watering to late morning or noon, it's set for 3am now.  How low can the temperature go before covering and for how long do I do this?  All winter?
Answer: I would begin watering the garden in the morning this late in the season.  The reason for this is the cooler temperatures and moister air of fall and winter tend to favor fungal growth, so watering in the middle of the night, as you are now, keeps the plants wet for hours before the warmer temps in the day can dry them out. This increases your risk of losing them to blight or mold.
Tomatoes are heat-loving plants, and begin to fade and sulk when consistently exposed to temperatures in the 40s.  So, if your nighttime temps there are hitting those kind of lows, I'd cover them soon and keep them well covered. I don't know what your winter lows are there or how well you plan to protect the tomatoes, but at some point this winter the plants may begin to become damaged by the cold even if covered.  I'd keep an eye on your expected low temperatures and harvest any full size (or close to full size) tomatoes before any hard freezes.  You can then ripen them at room temperature in the house.
The cooler temps won't upset the broccoli or lettuce - they actually like cooler temperatures anyway, but if you expect hard freezes then they should be covered as well for leaf protection.  On how to treat the herbs, it really depends on what types of herbs you are growing.  Basil, for instance, hates cool temps and will turn brown and be more susceptible to various wilts and rots once the night time lows begin to dip into the 40s.  Parsley and cilantro, however, like cool temps and will do fine with just light protection during much of the winter.  Thyme, sage and many other woody herbs are perennial and fairly hardy, so don't really need to be covered.  Rosemary can be marginal in some areas, but if you are Zone 8 or warmer, it should be fine outside in the open uncovered.


Please briefly define "futurum instans"

Question: I am writing a book, quoting from Aune: "There are several instances in Revelation of this use of ἔρχεται as futurum instans…" Note that Aune uses the term "futurum instans" for Greek, not Semitic languages. Google Translate tells the term as "be instant" and tells "futurum" as "the future" and "istans" as "instant". http://tbt.sagepub.com/content/66/2/129.abstract tells the term as "the imminent future, 'about to'". Perseus tells "present, immediate" for "istans" (nothing for "futurum"). If I want to give a brief definition of the term "futurum istans" to the readers of my book, could I give "the imminent future, 'about to'"?
Comment: The suggested edit you posted to the answer is useful information, but I don't think it's suitable as a part of that answer. Perhaps that could be given as a separate answer or as an addition to the question itself or a comment to the answer. I rejected the edit but I wanted to let you know of the reason. (Unrelated: Your two accounts can be [merged together](http://latin.stackexchange.com/help/merging-accounts).)
Answer: Futurum instans literally means "immediate/imminent future." ("Instant" comes from this word but has a different flavor in English now.)
Futurum instans seems to be a term especially prevalent in the grammar of Semitic languages. Most of the top Google results refer to Hebrew or Aramaic.  It appears to be a common term for a certain Hebrew participle (see here for instance.) I have traced it to Gesenius's Hebrew Grammar:

5 The use of the participle as predicate is very frequent in noun-clauses (which, according to §140e, describe established facts and states), in which the period of time intended by the description must again (see above, d) be inferred from the context. Thus:
(...)
(c) To announce future actions or events, e.g. 1 K 22, 2 K 416 at this season when the time cometh round, אַתְּ חֹבֶ֫קֶת בֵּן thou shalt embrace a son; so after a specification of time, Gn 74, 1514, 1719, 1913, Hag 26 (but in Is 2315, where, after וְהָיָה we should rather expect a perfect consecutive, it is better to explain וְנִשְׁכַּ֫חַת, with Qimḥi, as the 3rd sing. fem. of the perfect; on the form, cf. §44f); or in relative clauses, Gn 4125, Is 55, i.e. am in the act of doing; in a deliberative question, Gn 3730; but especially often when the subject is introduced by הִנֵּה (especially also if the subject be attached as a suffix to הִנֵּה as הִנְנִי, הִנְּךָ, &c.), if it is intended to announce the event as imminent, or at least near at hand (and sure to happen), when it is called futurum instans, e.g. Gn 617, 153, 203, 2413 f., 48:21, 50:5, Ex 313, 825, 93, 3410, Jos 218, Ju 717, 933, 1 S 311, 2 K 72, Is 31, 714, 171, Jer 3010, Zc 213, 38; with a participle passive, 2 S 2021.

In the context of English, the futurum instans is sometimes used to refer to the construction "about to V", e.g. "I am about to sing."
Since Biblical Greek often applies Semiticisms, it comes as no surprise that Greek ἔρχεται (ἔρχεται means "he/she/it goes") is employed in the New Testament as a parallel of this construction. It is often used with ἰδού for this purpose.
Steven Thompson, in Apocalypse and Semitic Syntax gives more information about this:

C.F. Burney was among the first to apply the Semitic participle of futurum instans in explaining the futuristic present verbs in the NT. He explains the futuristic ἔρχομαι found often in the fourth Gospel as due to Aramaic influence of this nature, and notes that in a majority of cases where the futuristic ἔρχομαι occurs, the Peshitta represents it by a participle. (pg. 32)

Pg. 32ff is replete with details and examples of this construction in the Greek New Testament.
Comment: It's a little hard to be sure from what's viewable of the Thompson book, but I think the Greek construction isn't actually ἔρχεται + verb in the sense of "be going to (verb)", but is just the use of the specific verb ἔρχεται (and a few others) in the present with an immediate future sense -- i.e saying "he goes" to mean "he's about to go".
Comment: @TKR You're right--I assumed that and revised my opinion after reading through some of Thompson. I just forgot to read through what I wrote :)

Please briefly define "futurum instans"


Can a countertop microwave oven be placed under the counter on a shelf?

Question: I want to know if a countertop microwave can be placed on a shelf under the counter.  If so what is the code required clearance for floor to bottom of microwave distance?  I live in California.
Comment: Floor to bottom of microwave? Isn't that determined by the height of the unit's feet? The issue is at the sides and above, where heat is exhausted. An inch all around is probably plenty, but we can't answer this rather vague question without more detail.
Answer: I don't think the code cares. What you need to look out for is mostly awkwardness in getting hot food out of the microwave, and not blocking the vents.
You can get pull-out microwaves that are designed to be easier to use when placed under the counter, but they're hilariously expensive ($1000+).
Comment: Expensive, smallish, and they don't even have a turntable for the most part.
Answer: The issue is not code. The issue is manufacturer's instructions. The good news is that you can find the manual for almost any current or recent appliance online, either through the manufacturer's web site or often through Home Depot or other retailers. Find a model or 2 that you like based on size, features, etc. and then download the manual to find out clearance requirements. Very often the requirements are fairly low, which is due to the way microwave ovens (as opposed to conventional ovens) work. Floor to bottom of microwave is not likely an issue at all - except that you want it at a height that is comfortable to use when removing hot items. The issues are normally back and/or side and/or top clearance for proper airflow.


Can Google Earth export kml files usable in the Google Earth Api?

Question: Is it possible for me to go through and edit my virtual copy of the landscape being worked on and export that to kml, usable in the Google Earth API? In other words if I have my models, and color markings laid over the earth, can I share those certain addons through GE API (not allowing users to edit it).
Comment: This is referring to Google Earth Pro
Answer: Yes.  There are a couple ways to do it.
In the left panel, right-click on the feature or features you want to capture in KML and select Copy.  Then open your favorite editor and paste.  You'll get the KML.  You can save the KML to a file.
Another choice is to right-click on the feature and click "Save Place As...", which will let you save the file as a KML or KMZ.
Google hosts a tutorial.
Answer: Sure you can, but you will have to create an GE API instance.
We are coming up with a new product that will handle that.
Send me a note to email@example.com if you are interested in knowing more about it and perhaps using it for your projects.
Best.
Jorge.


Does it violate copyright law if I include an image of a book page in a question?

Question: When I read a (math or statistics) textbook, sometimes I do not understand some of the equations or proofs in the book. Is it OK to take a picture of the page in the book (or ebook) that has the equations or proofs, and include it in the question as a supplemental matreial? Does this violate any copyright law?
Comment: If you're asking "does this violate copyright anywhere in the world", only a professional lawyer could say for sure, although [Law.SE] may be able to give you some information. However, in practice, SE doesn't care much about the copyright regimes in most of the world: US law is the most pertinent, although the EU or other areas may occasionally have effects as well.
Comment: Very complicated issue, and one that really cannot be resolved here  - see https://en.wikipedia.org/wiki/Berne_Convention, particularly the issue of "fair use".
Comment: I can't believe 9 people have downvoted this. It's a fair question, written to an ok standard.
Answer: I'm not a lawyer, so I can't really answer whether a certain use is a violation of the law. I can explain why putting such pictures in your questions may not be a good idea.
One problem with using pictures instead of text to explain your question is that they aren't searchable, so other people with the same question you posted won't be able to find the answers as easily. Another problem is that people with visual impairments may not be able to understand your question if most of it is described by a picture.
It would be best to try to transcribe or summarize the material that you want to take a picture of. You can include the picture as well (but be sure to put something meaningful where it says "enter image description here" and to include which book the picture is from) but your question should be able to be understood without it.


How do I modify the abstract in Arxiv (without changing the paper)

Question: I recently changed the location of a link to be in the abstract part. While it works perfectly in the paper, the link doesn't work of Arxiv (the main page) because it's in the end of a sentence and they added the "." to the link instead of realizing that it's the end of the sentence.
Do I need to resubmit even though i'm not changing the actual paper? How terrible is increasing the version of a  paper (I'll probably have to change it again in a month or two)?
Comment: I guess up to 5 times revisions are allowed for a one submission. If the submission is online, you cannot make any changes rather than v2.
Comment: It's going to be v3. How bad is it? does anybody cares (it's under review)?
Comment: All the versions will be available online, however your arxiv link to title refers to the latest version. I guess it's alright.
Answer: The only changes that do not generate a new version number are adding a journal reference or DOI. Changing the abstract will generate a new version. As far as I am aware there are no limitations to the number of updates, but at some point arXiv will stop including udpates in the daily mailings (I believe after version 5). Making many new versions with minor changes might give the impression though that you have not carefully checked your manuscript before submitting, so generally I would recommend to save such small updates for after the paper is accepted or revised. This would also be less work for yourself and for the arXiv moderators.
Personally, in the case you mention, I would not bother to update it now. Most people are smart enough to try to remove the period at the end of the URL.


Feynman diagrams

Question: Feynman diagrams are drawn on Space-time graphs. So is it possible for any particle path in that diagram to have a slope smaller than 45° or greater than 135°, i.e. can they travel faster than light? Does the slope or or velocity of the particles have any effect on the outcome of the diagram?
Virtual particles (photons and the like) should have no limits for their properties, but what about incoming particles, say electrons?
Comment: Also, for any increase in number of interactions in the diagram, the probability of that event decreases 100 times right? In these cases, do we also include cases where an electron emits and absorbs a (virtual photon), or when a photon splits into a particle-antiparticle pair? And does the actual location of the interactions matter? For simple electron scattering, what difference does it make if an electron emits and absorbs a photon while on its incoming path or on its outgoing one?
Comment: If you want more accuracy, you have to include cases like you mention that have one or more loops. If you are computing to one-loop order, you need to include all topologically distinct one-loop diagrams, because they might all be comparable in size. So, for example, if you include a diagram with an emitted-and-absorbed photon on one of the incoming electrons, you also need to include the diagram with the photon on that outgoing electron, and the diagrams with the photon on the other incoming and outgoing electron, and the diagrams where a virtual photon travels "across each vertex".
Answer: Incoming/outgoing particles with mass must travel at less than the speed of light. Incoming/outgoing massless particles must travel at the speed of light. The "virtual particles" inside the diagram can "travel" at any speed, but since they don't really behave like particles this doesn't matter.
Feynman diagrams aren't pictures of what is "really happening"; they are just calculational tools. "Virtual particle" is an unfortunate misnomer, and the emphasis should definitely be on "virtual" rather than "particle".
Comment: @Farcher also they might confuse the downvote with "like" and "not like" of social media, not realizing that in a science site one should defend ones disagreement  scientifically.
Comment: I am a physics Ph.D. who recently started contributing to this forum. It would be very helpful to me if the person who downvoted my answer would explain what was objectionable about it.
Comment: I find your answer fine. People who downvote and not support their disagreement  may be carrying a private view of physics. Somtimes they downvote without comment because they do not consider the answer addresses the question. Remember this is an international site,  and somebody might not understand/connect  your "really happening" to the spacetime question. I still get downvoted without comments, and have gotten used to it :).
Comment: @G.Smith Not me with the down vote. Unfortunately this is one small negative aspect of this otherwise excellent website which has not been addressed. When one is learning it is often not helpful if one gets a just a red cross and no explanation at the end of ones work.
Answer: Feynman diagrams are not drawn on space time, that is a common misconception. It helps to think of them as being drawn on space time, but the reality is a bit different.
Feynman diagrams are nothing more than abstract diagrammatic pictures representing various terms in the expression for the transition amplitude between quantum states.
Comment: The spacetime positions of the vertices don't matter because, according to the path integral point of view, you have to integrate over all possible interaction locations and times.
Comment: So other than any vertices or interactions, the rest of the diagram has no effect on the result whatsoever?
Comment: @user29774 The topology of the diagram has an effect. Not the positions of vertices (in fact, those positions don't even exist in the physical sense)
Comment: For each vertex, you get an extra factor of the fine structure constant, which is about 1/137.
Comment: It's not just the vertices that matter. For example, it matters which lines are for electrons, which for positrons, and which for photons. And the momenta and spins of the external particles matter.
Answer: Feynman diagrams are multi-faceted, since their origin [1]. Feynman starts by transforming equation of motion (Schroedinger's or Dirac's) into an integral equation and draws diagrams according to the title, i.e. in spacetime. He names $K_+$ the kernel (later known as "Feynman's propagator").
Sec. 6 of the paper is entitled "Energy-momentum representation" and here you may find the form of Feynman diagrams in general use afterwards.
In path integral formulation the integral is over configuration space for particles, over field configuration space for fields. In both cases, not over spacetime.
[1] R.P. Feynman: "Space-Time Approach to Quantum Electrodynamics", Phys. Rev: 76 (1949), 769.

Feynman diagrams