Armature with automatic weights problem. Object not following the bone properly

Question:
I tried to parent bones with automatic weights and 1 part of my model is working properly(the green one), while other is kinda "broken"(the red one) when I try to move bones. I don't know if that's relevant, but the "broken" arm is actually a clone of the original arm. Could anyone help me fix this pls? I could add more detailed pictures if needed.
Comment: Did you try looking if the weight paints of both bones are the same?
Comment: Are we looking at one mesh or many meshes for your outstanding figure?  An image of the outliner panel will help us to know.  Please submit your images from weight paint mode, which will be more important than the image above.  We are suggesting weight paint for inspection only at this point. You will need one with the weight group for viewer left arm and one for viewer right arm.  Selecting the groups can be done in the vertex groups panel for meshes.  Also feel free to delete the failed armature modifier and execute a new one.  Delete old one and create new one.
Comment: ok, I think I figured out what the problem is now... Its the weight that is messed up, ty a lot for help, Im very new to Blender><
Comment: @Gw1p Don't forget to answer your question.
Comment: Sorry, I forgot about this account and the question, which I quite awful... I have now selected the correct answer so, hopefully, it'll be of use to someone who's starting out with Blender!
Answer: When Blender automatically generated the weight for the bones it must have not completely covered the area of the bone.  What you need to do is select the mesh and go into weight paint mode.  Select the vertex group for the bone that is having problems, set the weight to 1.000, and paint the area around the bone.  That should fix your problem.  Painting may be needed on more bones than just one.
Comment: Yes, correct. I believe that was the issue I was having. Thanks!
Answer: The problem appers to be in vertices, that bones are connected to. Simply go to weight painting and change weights in a way they have to be


Can I record audio with a jack mic?

Question: I purchased a cheap Konig CMP MIC8 lav microphone that has a jack connector. Here is the picture of the microphone. https://i.ytimg.com/vi/KZclhiH5PZQ/hqdefault.jpg
My intention is to record audio with audio recording software such as Camtasia Studio, but when I connect the mic, Camtasia doesn't recognize it. It only recognizes the laptop built-in mic.
I assume I am missing some extra equipment here. I have a USB microphone which works well with Camtasia.
Maybe the problem has to do with the fact that my laptop has a single audio port for mic and earphones both?
Comment: This mic is meant to be used with a stereo line in port on a PC. You can use any USB soundcard with a stereo line-level 3.5mm jack socket.
Comment: Are you using mac or PC?
Answer: Your guess about the computer dual input/output jack is likely correct. You should pick up a TRRS breakout adapter (something like this) to split the stereo output and mono mic input.
Another possibility is that your software or soundcard aren't able to pass that info through, in which case you might need a USB A/D device (something like this).
Comment: The jack on the mic is a stereo jack.
Comment: Well, the jack is TRS but I don't think it's actually wired in any kind of stereo. That's a good point for troubleshooting though, since the soundcard could be doing something unexpected with the input.
Comment: I don't think he gave us enough information to give an answer yet. It could purely have to do with how his built in soundcard and computer settings actually route the audio. It's also different if he has Mac or PC since they both have different tools to route incoming and outgoing audio signals.
Answer: You need two things to make this work:
1) You need a MICROPHONE INPUT connector on your computer. This is typically color pink exactly like the plug in your photo.
2) You need to tell the operating system WHICH microphone to listen to. Most computers use the internal microphone by default, and if you plug in an external microphone (into the MIC input ONLY!) then you must go into the configuration menus and change which SOURCE it will record from.
It is also possible that Camtasia itself may have some configuration settings to enable it to "hear" your external microphone.
Since you did not reveal what computer/operating system/version you are working with, we cannot offer any specific information about exactly how to do this.

Can I record audio with a jack mic?


MMOs based on .Net?

Question: Are there any real MMOs where the server engine is based on .Net?
Comment: Are we talking engines/libraries for MMOs, or actual MMOs?
Comment: Converted this to CW as this is really just a "list of" question.
Comment: Related: http://gamedev.stackexchange.com/questions/4872/what-languages-are-used-to-develop-mmorpgs-like-eve-online-and-wow/4881#4881
Answer: RunUO and SunUO are free Ultima Online servers. Ultima Online client can be downloaded for free.

SunUO is a free Ultima Online server for Linux/Mono and Windows.NET, based on RunUO. Ultima Online is a commercial MMORPG by Origin / Electronic Arts.
Answer: Photon Socket Server is a middleware provider which is using C++ as the underlying framework but the bulk of the logic (i.e. what you have access to) is using .NET.
Answer: Sorry, those are Russian games, but I assure you they're very real MMOs and have servers made with .NET. I worked on these servers myself, in fact (-8
Arena Online
Elements of war
Comment: I only worried that you might not understand the language on these sites. Of course, being a Russian game developer myself, I know of King's Bounty and lots of other great Russian games. Lots of bad ones too (-8
Comment: dont worry!)) I think it is not matter Russian/Brazilian/American/German/etc if guys are creative. So if you wanna know "King's Bounty: The Legend" was made by Russian company "Katauri Interactive" http://www.kings-bounty.com/eng/screens.php
Answer: I don't know of any commercial MMOs off the top of my head, but the NetGore Engine, the successor to the powerful vbGore Engine, is looking pretty good. NetGore is currently in very active development with a growing community.
Answer: Second Life runs (at least partially) using managed code. They run on MONO, which is a Linux port of .NET. It's possible they're just hosting .NET within C++ for the scripts, but they are running it at least partially.
Answer: Lord of the Rings Online's client uses .NET 1.1. Not sure about the server. I think Turbine's games (LotRO, DDO, Asheron's Call) use .NET.
Answer: I have no idea of the server side but the DDO client throws exceptions that look like .net when it crashes.
Answer: Vindictus server is fully written in .Net. Vindictus offers only one logical shard with hundreds of thousands of simultaneous users, which can be done via function and data distributed computing techniques.
Answer: I'm pretty sure that CCP Games uses some .NET components on their servers.
Comment: Answers should be fact, and wherever possible support that fact with references (links). Welcome to GD.SE.

MMOs based on .Net?


Which is the correct idiom: "Force of habit" or "course of habit"?

Question: Which is correct, "course of habit" or "force of habit"?  (This question is inspired by this post on the woot forums.)
Answer: It is force of habit, and course of action.
The Corpus of Contemporary American and the British National Corpus reports the following data about force of habit (the reported values are the frequencies per million).
Comment: How did you make that nice graph?
Comment: I used _Numbers_, which is a electronic spreadsheet application for Mac OS X. I inserted the data, selected them, and selected the option to create a chart.
Answer: 1)perhaps the course of habit is when a person makes a conscious decision to do something and that action is then repeated until it is exercised without thought or remorse...
2)un-conscientiously doing something that is not an automatic until it has first been done out of willfulness.
the force of habit is that urge that pulls a person in after the person realizes that a certain action has become undesirable, and they do not want to entertain the action due to the undesirable consequences that are attached to the habit and wants to stop doing what ever it is that has now become literally part of the thought process... but the habit.... at this point has come to build a nice little home in your minds'  center and it is not about to give up easily, since this habit has been inside your head since the first time you opened yourself up to it, or invited it into and allowed it to become part of you.. The habit is very aware of your thinking and what it must do to make sure that, it too has a place to rest between episodes of your trying to kick the habit, start a new years resolution,, to change your ways, to start anew, turn a new leaf, so there fore the habit, does everything and says anything to tempt, tease, entice,encourage, justify,give false reason too, and manipulate, you into doing it one more time, "cuz things could be different just this once"


MySQL Remote Access Security Considerations

Question: I have always used MySQL locally using sockets. Now I need to access a database remotely. How safe is it and what would I need to consider? Is it sufficient to just use the bind-address or should I set up a firewall as well to block traffic?
Answer: You should setup firewall rules to just allow those hosts that need to access the host, and block all others. You could do something like the following, but this is just a snippet...
trusted_hosts="126.96.36.199 188.8.131.52 188.8.131.52"
for host in $trusted_hosts; do
    iptables -A INPUT -p tcp -s $host --dport 3306 -j ACCEPT
done

This assumes that you have set a default policy of drop with iptables -P INPUT DROP. Don't forget to add rules for remote access like ssh with iptables -A INPUT -p tcp --dport 22 -j ACCEPT.
Answer: You should always set up a firewall on the database server. There's no point in letting unauthorized people even attempt to connect to your database.  Past that, make sure you are using strong passwords (after all, you don't need to remember the password).
The MySQL protocol is unencrypted over the wire, so if you don't trust your network you may want to tunnel it over SSH, or use some type of VPN.


Is non-mainstream physics appropriate for this site?

Question:
Is non-mainstream physics allowed here?
What defines non-mainstream physics?
What sort of questions and answers are disallowed by this policy?
What should I do if I see a question or answer containing non-mainstream physics?

Return to FAQ index
Comment: Related: [Is Physics SE an appropriate location for peer review?](https://physics.meta.stackexchange.com/q/7516/)
Comment: There's also more conversation here:
http://meta.physics.stackexchange.com/q/5903/
Comment: re this ties in with a deep (studied) philosophical question https://en.wikipedia.org/wiki/Demarcation_problem also cf https://en.wikipedia.org/wiki/I_know_it_when_I_see_it
Answer: Is non-mainstream physics allowed here?
No, questions and answers about non-mainstream physics are not allowed here.
We are not a substitute for peer-review, and cannot evaluate new theories. While some questions can lead to legitimate new theories, the question will need to be specific in order to fit this format.
What defines mainstream physics?
Mainstream physics is physics which has been accepted by a significant portion of the physics community. In the case of modern physics, if a theory has not been published in a reputable journal, it is not considered mainstream.
What sort of questions and answers are disallowed by this policy?
Any post that attempts to work within the bounds of what we have determined to be "mainstream physics" is considered on topic for this site barring any other issues. For example, a question that proposes a new concept or paradigm, but asks for evaluation of that concept within the framework of current (mainstream) physics is OK. Similarly, a wrong answer that makes false statements but claims to work within the bounds of a mainstream theory is also allowed.
On the other hand, if a question or answer uses a non-mainstream theory as its premise and attempts to go forward in that direction, it can be safely closed or deleted.
What should I do if I see a question or answer containing non-mainstream physics?
Firstly, be certain that it is indeed off topic by the above rules. Note that if a post is simply wrong, leave a constructive comment explaining why, and downvote.
If the post is indeed non-mainstream, leave a comment stating the fact and linking to this meta post. For questions, flag or vote to close as non-mainstream. For answers, use a custom moderator flag mentioning that it is non-mainstream.
Comment: Regarding (1), sometimes I come along something in a paper or a pop-sci article, and would like to know whether it's legitimate or not. Say, the [Woodward effect](http://en.wikipedia.org/wiki/Woodward_effect), [Mallet's "Time machines"](http://en.wikipedia.org/wiki/Ronald_Mallett), and so on. I'd like to be able to ask "Is this mainstream science?" and if it's not, "Where's the author's mistake, why can't this work?". Do you think that's OK?
Comment: +1, I'd add two things: **1)** Questions *about* non-mainstream physics should be ok, e.g. ("Have Podkletnov's antigravity experiments been independently reproduced?", "Why do we believe cold fusion can't work?"). Questions *in* fringe physics aren't ok ("Where does the square root come from in this mass-formula?"). **2)** We should be careful about "questions that propose a new concept or paradigm". Those can be very useful, and generate research-level content, but they can also invite half-baked speculation (like "Are all particles the same string weaving the fabric of the universe"?)
Comment: Suggestion: Since "non-mainstream" is used both as (a) a euphemism for "crack" and (b) for things like Brans-Dicke theory, $f(R)$ theories, EC theory, etc., which have not been experimentally disproven, but neither have they been proven, ; I think a clarification, that by non-mainstream, whether it is meant (a) or (b) (As far as I know, it is (a)), is required.
Comment: This is concerning. All theories started as speculation. Can't we speculate appropriately? Ask questions? Figure out the nature of the world through thinking? What's so wrong with that?
Comment: @AndresSalas Feel free to do that in [chat]. Speculation invites discussion, and the SE platform isn't really designed for such discussion. Also, this invites a _lot_ of cases where people try to use the site to promote their own crackpot theories. These are detrimental, thus disallowed. Again, mostly anything goes in chat, so that's the place to discuss and speculate -- we do that often, especially in the biweekly (Tuesday) chat sessions.
Comment: @Manishearth: I was not suggesting that "Crack" is used instead of non-mainstream. What I meant is that, it should be defined with a few examples of what is mainstream, and what is not, is required. E.g., you could add something like,  "When, we say non-mainstream, we do not mean theories like Brans-Dicke, or f(R), but things like Heim theory, and pet theories." I know you wrote about non-mainstream meaning "not published in reputable journals", which is quite clear, but I think a few examples would help reiterate, and further clarify,  the point.
Comment: @vzn old post, but I thought I'd rebut; this website is not for the practice of science (developing new theories) per se; it's intended to act more like a reflection/explanation Q&A of what has already been developed... anyway, scientific inquiry is nuanced enough that judgment or valuation is often involved; the consensus aspect of scientific description is rather inescapable, SE Physics aside.
Comment: Food for thought... if the Internet and Stack Exchange had been around back in 1905, and Albert Einstein had tried posting his theories on Physics SE, it is likely that all his posts would have been quickly put on hold and then closed since his theories would have been considered 'non-mainstream physics' in 1905.
Comment: @HRIATEXP this is not the place to publish theories though. This is a question and answer site
Comment: @Dimension10 Uhh, no. "crack" is a very ambiguous and broad term that encompasses much more than what our policy does. Instead of defining non-mainstream in terms of other jargon, here it is clearly defined.
Comment: *"We are not a substitute for peer-review"* vs. *"For example, a question that proposes a new concept or paradigm, but asks for evaluation of that concept within the framework of current (mainstream) physics is OK"* I see a contradiction here, could you show me an example for both? What's the difference between the two?
Comment: Maybe there is a non mainstream way to discuss the maintream physics, which is to think what will happen if there is not something in the maintream physics. As far as I am concerned, This way could help to think deeper about mainstream physics.
Comment: Note that the goal of this site isn't to formulate new theories, it's rather hard to do that in such a way online. We try to make useful information about physics of all levels available to those who need them.
Comment: @jdm afaict (1) is not allowed, but I'm not sure. Regarding (2) That's actually OK. While the "one string to rule them all" question wasn't worded too well, it didn't fall afoul of the current non mainstream policy.
Comment: @Calmarius The questions on this site are sometimes of the latter form, one asks "does this work within the framework of classical electromagnetism", for example. In the scientific world, that's not a theory needing peer review. It's just a question. However, if you have a _new_ framework to propose, that's a theory needing peer review, not discussion on a website.
Comment: @qfzklmthe site is not for discussion. [chat] is for discussion, and mostly anything is allowed there.
Comment: this answer is problematic for various reasons, but in short one is that it to some degree reduces objective science to [sociology](http://en.wikipedia.org/wiki/Sociology_of_scientific_knowledge)
Comment: The most pertinent paragraph in this answer should be cleaned up.  It says, "Mainstream physics is physics which has been accepted by a significant portion of the physics community. In the case of modern physics, if a theory has not been published in a reputable journal, it is not considered mainstream."  The second sentence is either unnecessary or it is weasel wording -- lending a false sense of objectivity to the criteria.  Better would be a sentence operationalizing words like "accepted" and "significant".  For instance "published at least 4 times in science citation indexed journals".
Comment: Where should I ask questions about non-mainstream physics?  philosophy.stackexchange.com ?  Somewhere else?
Comment: My question marked as non-mainstream, but I am not presenting a new theory or denying something, I am just talking about a hypothetical clock in order to understand something else. That's not fair
Comment: @AbhimanyuPallaviSudhir --Consideration of Einstein-Cartan Theory as "non-mainstream" is quite inaccurate:  It was formulated by Einstein in collaboration with the mathematician Ely Cartan in 1929, a few years after the discovery of particulate spin (of which 1915's General Relativity took no account), and a torsion-based, inflationary (but without hypothetical "inflaton" particles) cosmological model has been formulated on the basis of it by Nikodem Poplawski since 2010, through many publications in highly reputable journals, by such publishers as Elsevier.
Comment: Perhaps you get many non-mainstream questions because it is not obvious that such questions are unwelcome. So the problem is predictability of this SE site. If you want people to follow a rule, the rule should be known. Otherwise it promotes the perception or fear that "of course non mainstream questions are unwelcome (potentially anywhere)". For example, you can add this rule under the question box. Or maybe rename the site to "Mainstream physics"? - As another answer in this discussion suggests. It is not clear why labelling the site "Mainstream physics" would be undesirable.
Answer: This is something one would expect in some "social" or even "humanitarian" branches of science (although i do not say that this is scientific, but it is indeed mainstream presently)
However it strikes me as very odd that positive branches of science (physics, mathematics, biology etc..) have to take such "measures" to guard a forum or a community from error or "heresy" or "non-mainstream-ness" (if i may use such a term).
It seems as if mathematics or even physics is a result of voting of which law is valid and is not a matter of natural reality.
It is as if some very wicked (but clever) person can divert the innocent viewers of this forum and make them believe other physical laws (by a mere manipulation of text and voting systems) hold in natural reality.
Of course in such a case "extreme measures" must be taken, the "natural" processes must be guarded from falling from their natural/realist (or should i say mainstream) status by voting them down or up.
Thank you.
UPDATE:
A recommendation:
Changing the forum's name to "mainstream physics" , since a definition of "mainstream" is in place it would indeed be valid and reflect the site's purpose and content.
Instead leave "physics" site name as non-reflecting the site's purpose and content.
It would lead to misunderstanding as encompassing talks / theories and discussions about actual physics (as in nature ) and hypotheses about physics etc.. instead of "mainstream physics" as some people want to frame it as THE PHYSICS (please nothing personal here).
Of course changing the name would immediately make apparent the fact that it is non-encompassing all physics or formulations or alternative hypotheses except what is sponsored (with a grain of salt) as "mainstream". This would beat the purpose of the mainstream (but not of physics) as trying to frame the talk around physics (and science)
One should not buy into that or accept that framing merely on mainstream authority.
Thank you again
Comment: This site has a problem in that it attracts (at a rate that is high enough that it would compromise the site's usefulness if left unchecked) questions which have very little to do with physics. Mostly, these are pet theories of people with no training or understanding of the standard framework their 'theory' is meant to replace. They can usually be proven wrong with a few sentences referring to some experiment, but the posters will typically be very aggressive and will rarely enter constructive discussions. The existence of this policy is thus a site-protection measure.
Comment: @NikosM. Proper capitalization, spelling and punctuation will in general help people take you seriously. In the end, of course, that is completely up to you.
Comment: The main point, I think, is that this site is meant as a place to discuss physics. It is *not* meant as a place to discuss with all comers why their pet theories are not physics, and particularly so if they get intransigent about it (which happens alarmingly often; constructive answers are possible, but constructive discussions depend on the OP). Thus, we reserve the prerogative to close questions which fall outside of what we're here to discuss. If you feel this is extreme, you are free to propose alternative measures and see if people are willing to put in the time to make them work.
Comment: "mainstream physics" is a horrible and silly name. Besides, in that case "no homework" would be a better name or "no homework/no non mainsteam physics/no engineering/no pure math/no black magic/ no politics/...". And the word Physics in this context already implies that it must have some acceptance. When I take a Relativity course I don't expect to be told that aether is real, when I read a Physics journal I not interested in some magical theory, etc.
Comment: To see a sample of such questions, try [this Google search](https://www.google.co.uk/search?q=%22We+deal+with+mainstream+physics+here%22+site%3Aphysics.stackexchange.com).
Comment: then that necessarily excludes non-mainstream physics. On a general physics discussion forum, they often accept the alternative or "crackpot" theories. And I agree to your point about Galileo and Copernicus. But this site wouldn't be the place for those theories at that time either. Our purpose is to explain how what we think we know is the truth of nature works. We are not a place to discuss whether that truth is right or whether someone else's ideas are better. This site is a compendium of the knowledge of current physics, but not the source of it.
Comment: I am really not very interested in debating this point. I have tried to explain why it is there and you can take or leave that explanation as you wish. If you want a warmer reception, I might suggest forming a complete picture of what the problem is before you accuse people of being closed or elitist (but again that is up to you). If you feel you have a more complete solution to the *problem* (which exists, and which you have not yet addressed), by all means propose it, in a thoughtful and respectful manner, to the community, and see what people think. Have a good day!
Comment: @NikosM. I've read through everyone's statements and I think there indeed is a misunderstanding about the function of this website. If we were a physics forum and what we wanted was what you seem to believe we want, then your "outrage" would be well deserved. However, Physics.SE is *not* a physics forum. We are not here to discuss physics; to have open discussions about the current state of research or the validity of (un)accepted theories. Our objective is essentially to teach/inform people of where physics is at....
Comment: I don't see how the measures are extreme. As Emilio said, these posts are a problem. However, it's easy for someone to argue that their post is "mainstream" as a matter of opinion, so we need a concrete definition that can be objectively tested against. That's what this policy provides.
Comment: We are a question and answer website. Ask a question about something in physics and we will tell you how the currently known physics would answer it. Our "mainstream physics" limitation is instituted because where physics is at is by definition limited to accepted physics. Any new or unaccepted theories may be completely correct, however they are not within the current understanding of physics. New/unaccepted theories may be unproven, they may need ironing out, or they may still be in development. But since we are only here to basically tell you what current physics thinks of an issue....
Comment: i agree with you, i am not saying this is not so, all i am saying is that this is not the best way to handle this or answer this. And in fact the positiveness of physics can make much easier to answer these questions very constructively. Apart from that i have many pet theries (as i think almost evryone outthere) and that i think this is good
Comment: Like a more interactive and more personal form of Wikipedia
Comment: @Manishearth, "extreme measures" is quoted on purpose, of course they are not extreme literally but just given an emphasis on what i described as a wrong approach
Comment: @EmilioPisanty, 'i' is on puspose, 'i' is not important, this is what i want to express and i cant see how this makes it more probable for rant that ANYONE else (which might capitalize it)
Comment: @EmilioPisanty, maybe we have (or i have) a misunderstanding of what this forum is and is after. Maybe this is true, still demonizing people just because they want to learn more or want to check their own understanding, is not sth i agree at all. The result is creation of groups of people that are assumed as elite by their own votes. Anyway this can be harsh so i leave it there. i still dont see the misunderstanding of the 'i' capiltalization or not (assuming you mean in a negative sense).
Comment: @EmilioPisanty, again you are wrong, you are constantly confusing form with content. Taken seriosuly or not is a matter of content. i did provide a solution, change the name to "mainstream physics". After all you have a rigorous definition of mainstream and this IS what you want to talk about. But you dont want that. You want to talk about "mainstream physics" BUT make it look as though you are talking about "physics". i proposed a solution along your lines. You will be surprised at how much mainstream you will look after that
Comment: btw i really dont care about the downvotes (or the upvotes). It seems that providing informationa and learning is a by-product of "hunting" for up-votes. i have the completely opposite stand, my main objective is information and learning and any up-votes (or down-votes) are just a by-product and NOT the main objective.
Comment: Having "mainstream physics" as the forums name (as it is infact), nobody will accuse you of not accepting to talk about his pet theories or alternative formulations or hypotheses or fringe views. And almost nobody (of those "bad/mad persons" will post there). Indeed it will solve most of the problem (if not all). But you will have to abandon the "insinuation" that "mainstream physics" is the only "physics" or the only "valid physics". So why dont you do that?
Comment: To be clear, this is my last comment on this thread, and I am not interested in debating this here. You should note, though, that voting on meta works differently than on the main site; (down)upvotes typically express (dis)agreement with a post's content, premises or proposals. So: you have made your proposal, and you have there a gauge on the community's opinion, which I would personally interpret to be along the lines of "we don't like your solution". I understand the impulse to change things but if you want the community to engage with you then you need to meet it halfway. Have a good day!
Comment: At the time of Galileo (and Copernicus, etc..), "mainstream physics" was the "bible" :). You should know better and while you expect people with understanding (at physics), at the same time you deny the very process which brings about this result. i dont want to post anymore
Comment: @Jim, *But this site wouldn't be the place for those theories at that time either*, exactly my point
Comment: what you call proper capitalization expresses a meaning i dont want to express, i am expressing sth else. Again you constantly confuse meanings.


BCH to BTC in same Trezor wallet

Question: I changed BCH in my Trezor to BTC using the wallet coin splitting tool and sent it back again to the same wallet using a new BTC receive address rather than another external wallet like eg Electrum using Shapeshift exchange. But the BTC didn't arrive. Have I lost the coins or are they just lurking in cyberspace waiting to be found again ?
Answer: If you sent BCH to your Trezor BTC address or vice versa, you can use https://trezor.io/recover-coins/ to recover your coins.  The only exception is if you send BCH to a BTC 3... address (segwit), since these are not supported by Bitcoin Cash.
To convert BCH into BTC or vice versa you need to use an exchange.
Answer: Double check your addresses as it is very easy to mix them up when dealing with splitting then Shapeshifting. You can check your transactions and wallet balances on the respective blockchains such as Blockchain.info for BTC and Blockdozer.com for BCH. In other words, you still may have both BTC and BCH as the transfers might not have transpired.
Answer: You can't convert BCH to BTC using the splitting too. You can only claim  BCH that you got as a result of owning BTC when Bitcoin Cash forked. So, after splitting, what you end up with is new Bitcoin Cash, not new Bitcoin.
If you sent that BCH to a BTC address, what you actually did was send Bitcoin Cash (not Bitcoin). This situation is already covered by joho's answer.

BCH to BTC in same Trezor wallet


Why was the question of the nature of light limited to the wave theory or the particle one ?

Question: The question is in the title. I'm obviously refering to the 17/18 th century somewhere around this era.
Comment: Because those were the ones on offer (by Huygens and Newton, respectively)? It is hard to tell what you have in mind without more context.
Comment: The question "is X one of those things we can use to describe it?" is not the kind of question scientists typically ask, philosophers like to ask such questions. They get on with it, test it, and keep it if it works. Old extramission theory was discredited by 17th century, "particles in motion" picture was generally popular since Galileo and Descartes, waves were a new exciting thing, and Huygens showed that they can account for all of geometric optics, just like particles.
Comment: Were there reasons to think back then that light had either to be one or the other of these two choices ? Or was it really just because this was what was offered only ?
Answer: A possible simple answer is that experiments on light manifested only the wave aspect of light behaviour or the particle one. These two aspects were not compatible, in the sense that light behaved as waves or behaved like particle depending on the nature of the experiment done. Heisemberg attributed this duality to the insufficience of our language to capture the real sense of the phenomena. By his point of view both aspects of light behaviour have to be treated as two different "representation" of the same phenomenon. More explicitly He remind us that already the category to which the terms "particle" and "wave" belong is the category of "a model"! He underlines that the products of radioactive emission going trough a Wilson Chamber shows themselves via a hyperfine-line of micro-droplets of condensend water supporting the "saying" that the radiation manifest itself as made of small particles moving at high velocity. On the contrary in the experiment of Davisson, Germer, Rupp, where one assume the particulate nature of radiation, since they also are products of redioactive decay, as a matter of fact they behave like waves giving rise to interference shapes similar to the one already known made by the X-Ray. In this case is appropriate "saying" that particulate radiation (see the source: radioactive decay) are indeed wave propagations. .... Heisember concludes that: "Matter cannot behave at once as particles and as waves and that the two "representations" are deeply diferent. The solution of this problem must be found in the sense that both are "models" i.e., they are simply similarities, that sometimes seams to validly apply, and in other occasions just fail. ... For instance, about the electron is simply proven in certain experiments that it behaves like a particle, but there is nothing saying that the electron possess all properties of the corpuscular model. "Mutatis mutandis", one can say the same thing about the undulatory model.". Up to now we dealt whith what we can say intuitively and using ordinary language. Heisemberg will take this, in accord with Bohr, as a starting point of the criticism of such level of knolwdge in order to found a proper logic reduction of the model theory and of the introduced analogous concepts.This in order to gain a mathematical coherent axiomatic from wich build the description of the new and unique nature of these phenomena. (from "Die physikalischen Prinzipien der Quantentheorie" 1930, in Italian "I principi fisici della teoria dei quanti" the text I used, and translate the best I could). I hope it can be of some use :-) ...
Comment: OP is referring to 17/18th century, when specifically wave aspects of light weren't known, let alone anything about radiation or Wilson chamber. Both theories could reproduce geometric optics, as could the ancient eye emission theories.


How to convert JPEG to RAW in Photoshop or similar?

Question: I am having a competition in which I have to submit images in RAW format. But I have already clicked some images with Nikon D3200 in JPEG.Is there any way to convert JPEG to RAW format in Photoshop or any other similar software.
Comment: In any case that you can "save" the file to any raw format, you do not have aditional info, so it is pointless. :o)
Answer: In addition to the points Alex S made, you need to consider why they want RAW.  There are several possible reasons:

Bit depth as Alex S said.
JPG suffers from compression artefacts which RAW doesn't.  Blown up to exhibtion size these can jump out and ruin a print.
Having the RAW file is often used as a proxy for having taken the photo, as RAWs aren't generally published.  This is to avoid cheating by submitting someone else's image. TIFF and other formats support high bit depth without lossy compression and are used for distribution of high-res images, so the only reason to have the RAW is that you shot the photo.
It's possible they want the as-shot image, though that's unlikely to be for display. Post-processing is part of the digital workflow, and the question is more one of how much is acceptable.  Having the RAW file gives them the ability to check how much you've modified the image.  I've seen RAW+TIFF submission requirements explicitly for this reason.

So you're probably out of luck this time.  I (as an amateur) almost always shoot RAW+JPEG, as many of my shots are just printed with at most a little cropping, but some need proper work.  This (if it's an option on your camera) may be an option in the future.
It is possible, if this is a local competition,  that they've just copied the rule from somewhere else, so it might be worth getting in touch with them.
Comment: Actually, as someone who has *run* competitions like this, a good chunk of that is good evidence of how little those in the 'competition'/club scene actually know about what they're doing...  Raw on the D3200 certainly does suffer compression artefacts.  The main reason for the raw request is (a) to prevent cheating and (b) to ensure only global modifications have occurred in photojournalism events.  I suspect if you contact the organisers and say you shot in JPEG they wouldn't have a problem with the entry, certainly won't hurt to ask.
Comment: For more on the third bullet point, consider [Why is giving clients RAW files such a sensitive matter among photographers?](http://photo.stackexchange.com/q/48078/1772)
Comment: @JanDvorak the normal jpeg algorithm can't be guaranteed lossless. The lossless algorithm isn't the normal algorithm. Rounding errors are a separate issue and more related to the image processing than the file/data format.
Comment: This is nearly perfect answer from a competition point of view. Thank you Chris H
Comment: @ChrisH well, you've got rounding errors, which might pass as "mathematically lossless", but also you've got the quality settings. JPEG is only mathematically lossless if you use the highest settings, but then the file size blows up by several orders of magnitude as the only regularity usable for compression are rounding errors.
Comment: @JanDvorak Lossless JPEG uses a predictive coding model, unlike regular JPEG files which use a discrete cosine transform.  It really should provide pixel identical images.
Comment: @JamesSnell There are other causes of artifacts in rendered raw images, such as when colors are interpolated from the sensor intensity values using the mosaic filter pattern.
Comment: @JamesSnell I'm sure there's a lot of copy-pasting of rules though up by someone who thought they knew what they were doing. My interperetation may not be perfect.  I must confess though, I don't get Nikon's RAW if it has compression artefacts -- what's the point of it?  Canon's CR2 uses lossless compression and the only Nikon SLRs I've used were 35mm
Comment: @ChrisH - Nikon has multiple raw options, though only the lossy compression is the only option available in the lower-end cameras.  The artefacts are really something that only pop up if you start pixel-peeping and only under certain conditions.  CR2 has similar problems as it also stores the main image data as a jpeg (source: http://lclevy.free.fr/cr2/) and while it's labelled 'lossless jpeg' I very much doubt that it really is.
Comment: @JamesSnell lossless jpeg is mathematically lossless ([wikipedia in case you're interested](https://en.wikipedia.org/wiki/Lossless_JPEG)).  CR2 also stores previews in lossy jpg.
Comment: @JamesSnell Can you point me to a list of Nikon (and Cannon) cameras vs lossy/losseless RAW formats?  While I'm not about to go buy a new camera based on ZOMG the RAW is lossy!!!!  I'm curious to see what the cutoff points for the formats are
Comment: @PeterM - not in comments, though it sounds like a good basis for a question.
Comment: One reason for RAW files in competition is to prevent most photo shopping.
Answer: RAW is not (or minimally) processed image data from camera sensor.
JPEG is processed image data.
Typically, raw-files from modern cameras have 12-14-bit per pixel which means up to 16384 values (for more details see Michael Clark's comment). JPEG can have only 256 luminance values per RGB channel. This means that jpeg contains much less data than a corresponding raw-file.
So no, there is no way to convert a jpeg to raw.
Technically, it's possible of course to convert jpeg data format to raw data format (like it's possible to convert a jpg to png or gif) but this will not make a raw-file and the organizers of competition will surely see that it's not a true raw file. However i have never seen such a tool and doubt that any exists.
Comment: Raw files don't have 12-14-bits per color channel. They have a 12-14-bit monochromatic luminance value per pixel. Each pixel is filtered for *either* red, *or* green, *or* blue. When the raw file is demosaiced colors for each pixel are interpolated based on the monochromatic luminance values of adjacent pixels filtered for the other two colors as well as the luminance values of nearby pixels filtered for the same color as the pixel in question.
Comment: `JPEG can have only 256 luminance values per color.` This is also technically wrong. I think what you meant to say is "values per RGB channel", and even that depends on the standard/compression used.
Comment: Alex S, thank you for in depth answer. I'll have to shoot those pictures again.
Comment: @MichaelMauderer Before edit I already had used "channel" couple of times so I chose "color" to avoid repeating :) Updated now.
Comment: Great!. Sorry the last part of the comment wasn't clear, the exact number of values vary depending on the encoding, and is mostly unrelated to the RGB channels themselves.
Comment: @MichaelClark the exception is a Sigma camera with a Foveon sensor, it *does* capture all 3 channels at each pixel location.  I'm sure you already knew but simply neglected to mention it :)
Comment: Are cameras with Foveon sensors even still being manufactured and sold new? Even if they are one would probably be safe to guess they comprise less than 1% of the world's camera population. ANd that's probably before you even count all of the cell phones, tablets, etc. with Bayer masked sensors.
Comment: Of course tools to convert to raw exist. ImageMagick can do that with many types of raws.
Comment: The question was "How", but the answer is "Why".
Comment: @tnJed the answer not "why", the answer is "it's not possible". So there is no HOW.
Comment: @Zenit "Technically, it's possible of course to convert jpeg data format to raw data format" - the answer. Using another answer I was able to do it fairly easily.
Answer: You cannot (should not) produce a raw from a jpeg.  Theoretically it would be possible as compressed NEF is based on a TIFF container and a "wide" JPEG/JFIF variant IIRC.
And all is not lost as, having run these kinds of competitions, I can say that you may still be able to enter depending on what type of competition it is and why they want raw files...
The requirement may be there because the competition is for unmodified images - this is common with photojournalism competitions where only blanket or minor changes are permitted.
More likely the requirement is there to discourage cheating, which has been rife in the amateur/competitive world.  Assuming that everyone shoots raw (and some people don't - and no, I've never understood doing that) organisers will often allow you to supply the original unmodified jpeg you based the entry on as actual entries are usually requested at a specific pixel dimension.
Some organisations post requirements like that under the guise of 'quality', though that's mainly bogus as (even now) few devices are capable of going beyond 8-bits per channel.  From my observation it's mainly to keep "newbies" out.  From experience I've seen plenty of events ask for 24/48-bit lossless RGB TIFF to then display it on some awful DLP projector which doesn't have the tonal response to make a calibration worth attempting (if they had attempted one, which is far less likely than you might expect).
In any case even though the rules are listed, they are usually about maintaining fairness and will have some caveat that the organisers have discretion over submissions.  You should contact the organisers and explain that your original was shot in JPEG as they may still allow you to enter.
And good luck in the competition!
Answer: There exist methods to do this, but as Alex. S also points out in his answer, there are no standard tools that I'm aware of that will do it for you. In principle, it's a straightforward problem. While there are a vast number of mathematically possible  raw files that are consistent with the given JPEG file, the vast majority of those are not likely to be the original raw file. This means that you can try to approximately reconstruct the original raw file using maximum likelihood methods. This requires one to specify a prior probability distribution over the set of raw files.
Similar methods are used in some noise reduction algorithms, here one calculates the most likely noise free picture, given a noisy picture. It turns out that even with simplistic models for the prior probability distribution, one can obtain reasonable results. In the exactly solvable case of a Gaussian prior where one assumes that the prior probability is product of Gaussians of the differences of the gray values of neighboring pixels, the solution is an oscillating Gaussian filter. Noise reduction is then achieved by averaging, but there is then no net blurring due to this averaging, as blurring is counteracted by sharpening due to the alternating positive and negative weights of the filter (which has the analogous effect of an unsharp mask).
Answer: There is a very nice tool to remove JPEG artifacts and get DNG file out of pixels. Sure, it can't reconstruct HDR and other details, but still it may be helpful. The application uses machine learning (convolutional neural networks) to process input image (e.g. remove compression artifacts and slightly remove noise) and don't make it blurry as using just gaussian blur with small radius / box blur. Also, the output DNG file is processing well with Lightroom / Rawtherapee.
The application "RAWerse Alpha" (https://rawerse.com). And they provide a demo version.
Comment: link is broken.
Answer: Raw files are basically digital negative of an image. At the same time jpeg is optimized output created by camera. jpeg cannot contain so much data that a raw file can, so its impossible to convert a jpeg image to raw.
Answer: This is probably a little late but Capture NX 2 allows you to save a jepg as an nef format file, it as others have said is not going to be a raw file in that it has no more information than the jpeg but it will, if that was the requirement, be in Nikon's Exchange Format.
Answer: Converting a jpeg to a raw file is technically possible, but any photo contest is going to notice the missing data. Actually making a raw from a jpeg would be like publishing a book using 120 characters or less. All the EXIF data would be missing so they cant confirm or deny any criteria they may be judging or disallowing.
Comment: This doesn't sound right.  A JPEG has had the raw photosite data combined and you can't just separate it back out.  If that was possible, there would be no reason to need to shoot in RAW.  You might be able to make a completely arbitrary RAW file that could have certain settings applied to produce the JPEG I guess, but it would be a total mess.  There is also no reason that EXIF data couldn't be in the JPEG just like in the RAW file.
Answer: Corel PhotoPaint will convert JPG files to RAW. Comparing file sizes shows the degree of data loss in JPG.  However, if the size of the JPG file is large -- a function of the number of megapixels and the color variation in the photo, and many other factors -- could not the JPG be converted to RAW to 'hold' the original so it does not deteriorate with manipulation?  That way, compression of the original will not happen as its JPG version(s) are manipulated.


What is the relationship between the focal length and f number of a telescope compared to a guide scope?

Question: How do you determine the optimal length of a guide scope for a given imaging telescope?
I imagine it would have to take into consideration the pixel size of the guide scope, but would the aperture matter as well?
Comment: Perhaps consider ticking one of the answers below that you find most helpful?
Answer: The aperture of the guide scope matters because it affects how faint the stars are which are available for guiding - the larger the aperture the fainter the stars it will pick up which gives you more choice when picking a good one as a guide star. This is especially important if you are imaging from an urban area where light pollution may otherwise limit the number of visible stars.
The length of the guide scope is not directly important, although generally larger diameter objective means longer anyway. The weight of the guide scope does however have to be also considered as your mount has to be able to deal with the extra load you are placing on it, lighter is better here of course.
When you talk about pixel size I presume you mean pixel size of the CCD camera you are attaching to the guide scope itself? I am not expert enough to go into great details there, if you need more in depth advice on that side of astrophotography I can thoroughly recommend the Cloudy Nights forum, there are some very experienced astrophotographers on there who are very willing to share their knowledge and experience with all no matter how much of a beginner you may be.
Answer: Don't worry about the main telescope. There doesn't have to be a relationship between the focal length and f ratio of the telescope and the guidescope. I think this is proven by the use of off-axis-guiders, which use the same focal length as the telescope. They just come with the headache of finding guide stars.
What is important is: can the guidescope provide data for the controlling software to accurately automate the telescope?
You want a wide, fast field of view, so that you are guaranteed to be able to find a bright star to guide by.
You want a camera on the guidescope that has sufficiently small pixels that the guide star that gets picked will at least cover a few pixels - the more the better. To some extent, this conflicts with the wish for a wide, fast view, as that will result in smaller stars on the sensor. This can be mitigated by ever so slightly de-focusing the guidescope so the stars form fuzzier, larger circles on the sensor.
What is more important that the focal length of your telescope will be: (a) what the limit of your seeing tends to be, and (b) the accuracy with which your mount can be controlled, and (c) how accurately the guiding software can place the guide star (usually a fraction of a pixel - use maybe 0.2 pixels as a worst case, if unknown).
There is not much point in being more accurate than the seeing permits.
The formula for figuring out how much each pixel sees is:
$$
px_{fov}=206*px_{microns} / f_l
$$
where f_l is the focal length of a telescope and px_microns is how large each pixel is on the sensor.
You can therefore estimate a suitable focal length guide scope this way:
$$
f_l = px_{microns} / (res_{seeing}/G_{acc}) * 206
$$
where px_microns is the size of the sensor pixels,
res_seeing is how accurate you need the guiding to be,
G_acc is the guider software's centroid accuracy (use 0.2 as a worst case if unknown)


Tracking punchlist items in a project plan

Question: As a project gets closer and closer to handover to QA, I find myself tracking a list of outstanding items that need to be completed before the software is completely ready for testing.  I'm trying to think of a way to do this that's more rigorous and visible - so that everyone is aware of what needs to be done and so things don't fall off the table.  One possibility I'm considering is simply logging problem reports (trouble tickets) on the items which are outstanding.  Would it be better to add them as explicit tasks to the project plan or is there a better way still?
Answer: For me the answer is hidden in a question. You want to make these things visible? Well, make them visible. Visualize your punch list, possibly on a physical medium and in a place which is frequently attended by the project team, be it a room they share, a hall or the place next to a coffee machine.
Using physical medium - a whiteboard or flipchart serves two purposes:

It gives a big picture to everyone. If the list is in bug tracker or something I likely filter out items which aren't assigned to me, thus I don't see what others have on their plates, thus it's unlikely that I consider helping them. With a physical board I want it or not I see the whole thing.
It makes the message more accessible by everyone. Whenever people are walking by the board they will take a quick look at it and possibly learn that something has changed or there is a problem with one of items etc. It is sort of learning "in the meantime." That's why the more crowded the place is which you put your board in the better.

There are also a few pleasant side effects:

Physical board is extremely flexible. You can draw a picture if you like, or attach a sticky which means something, e.g. a blocker, or have cool avatars of people who are assigned to tasks, etc.
It serves as a continuous reminder what else there is to be done. You can forget to log in into the app which stores your list when under heavy workload but you will eventually take a look at this big thing on a wall.
If the board is in a room the team works in you get additional information - everyone sees that someone comes to the board and changes something, thus they get an update in a very non-intrusive way.
It is a place where you can meet during project meetings to discuss most important and urgent things to deal with.
It gives you the place where you can do some brainstorming without losing a context. You can just use the empty place on the board.
It is fun. Definitely more fun that yet another bug tracker.
Comment: Unfortunately, this isn't physically possible for many teams nowadays because of their virtual nature. I'd offer that something that's easily put 'in your face,' not too cluttered with details and that's easily added to/updated is what's really needed. For this I've seen the landing/home page of the most commonly used tool as a good means to do this. We use the home page of our team's Sharepoint site to display this type of info.
Comment: That's true. In this case it is a question of value: one solution might be physical information radiator/board in PM's place if the focus is on PM tracking down each and every issue, or software based solution, as flexible as possible which is easily accessible for everyone in the team, or a combination of both. Either way, if physical board is feasible I'd definitely go for that.
Answer: Try a bug tracking application or issue tracking application.  Many people have given great suggestions on the site under the PM Software tag.
Comment: It's more of a process question than a request for a bug tracking app recommendation - we have a bug tracking app.
Comment: Thanks, that clarifies it. Who is responsible for completing the tasks? Are these outstanding items for yourself, for the development team only or for various people on the team?  Do these items need to be tested/validated during testing?
Comment: Various team members have tasks; yes, this work would be subject to scrutiny by QA.
Comment: Then yes, included them as explicit tasks on the project and as items to be validated in QA.
Answer: Does everybody need to be aware of what must be done? I think this might cause you more troubles if you have nearly completed development.
Regarding issue tracking. If it's a bug/defect/issue, then it should be formally logged, analysed and then tasked up. E.g. I found a bug on the live system. I have logged it. Front end senior developer has picked it up and analysed it. Another web developer knows how to fix the bug, so he then tasks it up, gets it approved by relevant parties and then starts development.
If it's just a task/feature, then it needs to be analysed in exactly the same way.
It doesn't matter at this stage whether it's in a bug tracking application, document sharing application or excel. As long as it's consistent and clear - you'll be fine.
Relevant stakeholders must be aware of this feature/task/bug, NOT everybody.


How can I write a script to move ETH from many wallets associated with a mnemonic to a single wallet?

Question: Would be grateful to be pointed to any resources that would allow me to do this.  Thanks!
Answer: You need to first parse all the accounts in your HD wallet.
For example, if you have a Ledger Nano, there is a script here.
Or you can just generate addresses from a predefined mnemonic with ethereumjs-wallet as described here.
Finally, once you have the Nth address generated by the HD wallet you can just use:
web3.eth.sendTransaction ( { from: nthaddress, to: singleaddress, value: web3.eth.getBalanceOf( nthaddress ) - fee } )
to do the transaction
where nthaddress is the deriveAccount with the path m/xx'/yy'/0'/.. ( e.g.: "m/44'/60'/0'/0/0" )
Comment: Thank you so much, Andrei!  I'm attempting this, but am hitting the following error:  CONNECTION ERROR: Couldn't connect to node https://mainnet.infura.io.
    at Object.InvalidConnection (/home/ubuntu/server/node_modules/web3/lib/web3/errors.js:31:16)
    at HttpProvider.send (/home/ubuntu/server/node_modules/web3/lib/web3/httpprovider.js:87:18)
    at Eth.send [as getBalance] (/home/ubuntu/server/node_modules/web3/lib/web3/method.js:145:58)
    ....etc. Could you advise?  I'm quite new; apologies if the solution is obvious.
Comment: I don't know much about `infura.io` , all I can suggest is to run your own node (eventually a light node like this https://redd.it/6lzw8y ), sorry...


Lightswitch multiple grids on same page from the same entity causing issue when adding a new item

Question: We have a entity called workingfields based on a sql table.  There is a type field in this table so we can store different types of working fields all in the same table.  We then have 5 different grids on one screen that are based on the workingfields entity but each is based on a separate query we created off of the workingfields that filters it by a specific type of working field.
So our grids each only show the items that match that type.  When we add a new item to one of the grids, it adds it to the bottom of all of the grids.  If we hit save and refresh, it will save it with the right type because we are setting that when we add a new entity in the grid and it goes away on the other grids when we refresh the screen.  But, Its like the queries filter for the grids to show us the data we want but since they are all based on the same entity called workingfields lightswitch thinks we want to add new to the entity and it shows it on all the grids even though we want it to show on only one grid.  Is there a way we can only have it add new on the specific grid we want and not on the entire screen?
Answer: Maybe obvious, but have you tried breaking each grid out into its own separate screen?


Why does Quicksilver hold Magneto's head, but not everyone at Xavier's school?

Question: In Days of Future Past, Quicksilver holds Magneto's head to prevent whiplash. However, in Apocalypse, Quicksilver not only ignores holding heads (not everyone), he also throws people. Did they make a movie mistake, or is there some explanation of this?
Comment: Not sure what exactly the situation in Days of Future Past was, but in Apocalypse he had a lot of people to save in a relatively short amount of time - probably not enough to be able to worry about that for everybody he was saving. Alternatively, it wasn't actually required in DoFP, he just didn't know that yet so was playing it safe. [This question](http://scifi.stackexchange.com/q/74417/5833) suggests that in reality holding the head is probably irrelevant and they're still going to suffer fatal damage. Ultimately, it's comic book physics plus the Rule of Cool.
Comment: Because the movies are not self consistent.  They are not self consistent because they are not written to be self consistent.  They are not written that way because the studio values the instantaneous perception of "hey that is cool" over their concerns that we will find plot holes later.  They value that because that allows for easy trailers and they believe it is better for casual fans.  The net result is they do not develop as strong a fan base as MCU films but make comparable profits. This is all out of universe. In universe: Grist's genius 2nd idea or he finds time to decelerate in Apoc.
Answer: In Days of Future Past, Quicksilver was trying to get one important guy out of jail. Key aims: keep Magneto safe, and get him out in the few minutes before the whole place is on lockdown.
In Apocalypse, Quicksilver was trying to get every student out of an already-exploding school. Key aims: get everyone away from the explosion in the one or two seconds before it engulfs and certainly kills them.
As such, he doesn't have time to hold everyone's head. More risk of injury for any given individual is acceptable, given that the alternative is immediate firey death, and he's got a lot of kids he wants to save in a very short period of time. As you'll notice, some kids he just literally throws out onto the ground.
Sorry! No movie mistake for you today!
Answer: I can't remember him doing that in the film. But it may be, as someone has already suggested, that he was playing it safe. It may be important to note that Magneto is Quicksilvers father. This is alluded to in DoFP and confirmed in Apocalypse. This may be why he was more cautious with Magneto than he was with others.
Comment: As far as I know, Quicksilver did not know Magneto is his father in DoFP. He might suspect but did not know for certain. The dialogue in the elevator goes something like this: "You can control metal? My mother knew a guy once who also could control metal."
Comment: It was never confirmed whether he did or did not know at that point. Nonetheless, the allusion exists to poke fun at the fact that Magneto was his father in some comics and to reference those comics. The fact that he acknowledges in Apocalypse that Magneto is his father suggests to me that it was a little more than an inkling that he had. This explains why he would be more careful with Magneto than he was with others.


Honor parents who want you to violate halacha?

Question: Suppose a parent feels very strongly against a certain aspect of halacha, for whatever reason. What would be an appropriate way to follow halacha while maintaining kibbud av v'eim?
Comment: Are you looking for halachot of kibbud av va'em, or are you looking for discreet-mechitza construction advice?
Comment: @DoubleAA The mechitza is just an example. I'm talking more about the general case of a parent wanting the child to not follow halacha.
Comment: In spite of my answer, I would strongly advise you to CYLOR, since I don't believe the example you gave is necessarily one that rises to this level (which is why I deleted it).  I could be wrong, though, which is why I again advise you to CYLOR.
Answer: If his father told him to transgress one of the words of the Torah, whether a positive commandment or a negative commandment, or even something from the words of [Chazal], he can't listen to him. Yoreh Deah 240:15.
However, if he sees his father transgress something, he shouldn't say "You transgressed," but he should say "It says such-and-such in the Torah" (above, 11)
Comment: See the recent edit and also the chat discussion here http://chat.stackexchange.com/transcript/message/5749612#5749612
Answer: Vayikra 19:3 states:

ג  אִישׁ אִמּוֹ וְאָבִיו תִּירָאוּ, וְאֶת-שַׁבְּתֹתַי תִּשְׁמֹרוּ:  אֲנִי, יְהוָה אֱלֹהֵיכֶם.
Ye shall fear every man his mother, and his father, and ye shall keep My sabbaths: I am the LORD your God.

From the juxtaposition of the two clauses in the verse, the Talmud (Baba Metzia 32A) learns out that one is not required to honor one's parents if they demand he transgress G-d's commandments.
[in other words, they learn the verse like this: One must fear (and honor) his parents. Just like that is a commandment from G-d, so too is keeping Shabbat (i.e. the other commandments). Honoring one's parents does not trump other commandments. If they want you to transgress other commandments, you are not required to listen.]
This is the source for the Halacha brought in @ba's answer.
Comment: See the recent edit and also the chat discussion here http://chat.stackexchange.com/transcript/message/5749612#5749612
Answer: I'm going to echo Menachem's answer but go one step further.  I have learned on many occasions that it isn't that one is required to follow Halachah despite the apparent conflict with Kibbud Av VaEim.  It is, rather, that there is no Kibbud in this case.  In other words, it's not a conflict.  The instant that a parent's desires rise to conflict with a point of Halachah, the requirement for Kibbud falls away.
Having said that, I understand your desire not to upset your parents in any case, and my advice would be to explain to them that [Halachah X] is just what we do, and that you hope they will respect your choices.
Answer: I'm not sure I understand your question. Are you asking "am I obligated to honor my parents", or "what's the best way to blow them off without blowing them off?"
The example you give -- mechitza at a wedding -- is a practical and halachic preference but you'd be hard-pressed to explain why it's "required." (Men not dancing with women? Obligation according to everyone. Men not sitting with women? Depends who you ask. Having a partition up? Good idea to prevent gawking but I don't know if anyone requires it.)
In short: it depends.
Three questions:

If you believe the action is halachically wrong, how wrong is it?
How broad is the obligation of honoring your parents?
What are the limitations on reasonable requests?

How wrong? If a parent orders you to violate a clear-cut commandment, whether Biblical or rabbinic, whether by commission or omission, then you ignore your parent.
But there can be things of positive value that aren't absolute commandments. (See Pischei Teshuva discussing a series of this in Yoreh Deah.) For instance: Bob's mother died, so Bob is saying Kaddish in shul. Bob's father Tom hears Bob saying kaddish and gets the heebiejeebies, reminded of his own mortality. Tom orders Bob not to say kaddish. -- In this case, it's debated in the Achronim but we rule that Kaddish, while technically post-Talmudic and therefore post-rabbinic, is strong enough to override parental wishes. If, however, Tom says "Bob don't wear mourning colors!", Bob should acquiesce.
So if you go to a rabbi who believes, for instance, that ordinary milk sold in the USA is downright rabbinically prohibited and say "my parents want me to drink this", he'll tell your parents to go jump in a lake. (Because, um, well, if they go to mikva more often it will make them more spiritually attuned to the horribly destructive effects that chalav stam has on your neshama.)  If the rabbi holds it's a halachic preference but not requirement, then the pros and cons get weighed.

How broad is the obligation to obey? Maharik says anything not directly affecting the basic physical needs of the parent isn't included. (Therefore, according to Maharik, a parent who says "don't marry her" has no standing for his request whatsoever.) As I understand it, Rabbi Hershel Schachter shlit'a leans towards this view. Yet many others say a parent can ask for all sorts of things that are tangentially beneficial. (Rabbi Mordechai Willig shlit'a describes the Chazon Ish is a "maximalist", which is Rabbi Willig's approach as well.)

Limitations. Chazon Ish writes that one is only obligated to accommodate a reasonable request; beyond that, "the parent is obligated to cancel his request." For instance a parent can't demand all of a child's money.

So what's practically recommended will vary from case to case.
In the situation where there's no gray, e.g. "I want shrimp served at this wedding", then philosophically our approach is that we can honor people without necessarily obeying them.
Comment: Starting off an answer with, "I'm not sure I understand your question. Are you asking..." is a sure way to cut a reader's confidence in the quality of your answer. May a recommend a comment on the question instead?
Comment: do you have sources for the Maharik and Chazon Ish?
Comment: @Menachim: Maharik: responsum #166 (though it's 164 or 167 in some editions). Chazon Ish: Yoreh Deah 149:8. Go to yutorah and try Rabbi Willig's pdf and mp3s on Kibud Av V'Em for more.


How can I store still hard apple in a barrel before drinking?

Question: I am a beginner homebrewer, so I will explain my situation in more detail to make sure I am making still hard cider correctly. Recently, I started my first batch by adding 1 gallon of pasteurized store-bought apple cider to a carboy along with a packet of Lalvin-E1118 yeast. So far, I've put an airlock on it and have left it alone for about 2 weeks. My question is, when exactly do I start secondary fermentation, how do I do so, and is it possible to store the still cider in a wine/whisky barrel with a spigot instead of bottling? I am not ready to start carbonating and bottling the cider until I have found a tasty recipe that I like. Also, I tasted the primary brew and it is very sour. Is there a way to make the cider sweeter? Thanks
Answer: Making cider is a good entry into the great hobby of homebrew.  Sounds like you've started the project properly--it's pretty easy to make cider.  However, I'd suggest you take things slowly and skip the barrel for your first batch.  Get to know the basic process and variables first. Wait till you're comfortable with the ingredients and process, then, when you have a some special juice, try out the barrel.
Secondary fermentation is usually a misnomer and an unnecessary step.  For your purposes, just let it stay in your primary fermentation vessel a few more weeks. Watch the airlock--when it stops bubbling, give it another weeks or two, then put it in bottles.  No need to carbonate if you don't want to.  If you bottle too soon, and some sugar hasn't fermented out, you will get a bit of carbonation in the bottle
I'd suggest getting a hydrometer and recording the specific gravity (sugar concentration) of your cider before fermentation, then when you think it's done.  With experience, you'll learn what gravity level indicates that fermentation is complete given different juice and yeast.
If the cider is actually sour, then you might have had some bacteria get into it and make a bit of vinegar.  Make sure you're sanitizing everything carefully.
Otherwise, use some potassium sorbate or other "stabilizer" which will deactivate your yeast then add your sweetener.
More of all, have fun and enjoy.  Keep things easy and experiment more.
Answer: You have several questions there... Secondary fermentation in the brewing world is usually meant to be secondary storage. Now cider being closer to wine than beer since it is made out of fruit juice you could send the cider through a secondary fermentation called Malolactic Fermentation (MLF). This might actually help with the sourness your are tasting which probably caused by high acid levels. MLF eats the malic acid (green apple flavors) and turns it into lactic acid (softer).
There are ways to make it sweet. Simply putting more sugar in will not work. The yeast will eat it. You can use chemicals to kill the yeast or sterile filter and add sugar, you can make a sweet cider. But all this is advanced stuff.
I would skip the barrel, just store your cider in another carboy. You don't want any headspace between the cider and bung, maybe an inch. While you can store cider in an old whiskey barrel, I think that's a little too much to take on your first try.
I really suggest getting a book or watching some youtube videos on cider making.


Should reference request be used if book-recommendation is already used?

Question: If one tags a question with book-recommendation should one also tag it with reference-request? I think it is redundant, although it is actually a reference-request question.
Comment: The original goal of each SE site is to be a great resource for great answers to real problems (more or less). A big part of this is to be searchable Q&A. So we want descriptive titles, clear questions with context, and accurate tags. Each of these makes the question stand the test of time better and be more searchable for others who are encountering the same problem later on. Further, as the site grows, it becomes far more reasonable for people to browse questions in tags that interest them. MSE is starting to feel these growing pains, and tags are more necessary than ever.
Comment: In short, one should use as many tags as correctly identify the problem. If there are too many available, choose the best 5. For a generic [tag:book-recommendation] question, I might expect [tag:reference-request]. But if you find yourself in a position where you have more than 5 good tags, then dropping off the less-specific duplicate tag is a great start.
Comment: Great, thank you. I didn't know we should try to find five relevant tags whenever possible.
Answer: Note that the tag-excerpt  currently says (emphasis mine):

This tag is for questions about recommendation of books for some particular area, topic, problem. Use this tag together with (reference-request) tag

So users who add both tags use the tag in accordance with the recommendation in the tag-excerpt. (One of the main purposes of the tag-info is to give some guidance for using the tag, especially in the cases when the usage is not entirely clear from the name of the tag.)
This version of tag-exceprt was suggested here, mainly for the historical reasons. (book-recommendation is a relatively new tag. There were already many questions about book recommendations tagged reference-request. It would be difficult to retag them all. And, moreover, many users might not have noticed creation of the new tag and might be used to search for book recommendations under reference-request.)

Of course, it is possible that the outcome of the discussion at this question will be that it is better to keep the two tags separately. If that happens, we will simply change the tag-excerpt and hope that enough users note this discussion or read the tag-info. Users aware of that change will help with correct use of the book-recommendation tag. (The word correct here stands for "being more-or-less community consensus". Maybe more precise would be "consensus of the users which participate or vote in meta questions about tagging, which is usually not too many.)


Restful Webservices

Question: I have a scenario where I have to call a webservice whenever there is an update on the record of a standard page layout and handle the JSON output. Since it is on standardlayout I have used a trigger and an @future call but I am unable to return the JSON for the request. Is there any way to handle this or any suggestion on how to handle webservice call on standard layout will be appreciated.
Answer: You cannot return a response from a trigger, which can be synchronously displayed to the user (other than using addError, which wouldn't fit your use case) .  A trigger is meant mainly for business logic.
You could have a custom text field Result on the object, which you populate with the result of the ws callout after processing the json response.
If you must display the response to the user synchronously, you will need to override the standard button with a visualforce page or replace it with a custom button and use the Ajax toolkit to make the ws callout and display the response.
Answer: By handle the web service on the standard layout I assume you want to display the results from this webservice to the user as soon as they update the record.
Add an inline visualforce page to the page layout that runs an action method on page load that checks if the record was just updated by the running user and if so makes the webservice callout and displays the results on the page.
Depending on how often you need to query for the information from the webservice and how quickly it becomes out of date you can either just display the information on the vf page and not save it anywhere or save it on the sObject and only re-query for the information after a certain time-out period.
Answer: It is always better you make a custom button on the standard pagelayout and once an update is done for the record for specific fields indicate to the user by alert or pop up to press the custom button and on action of that button call the external service.

Restful Webservices


Can exploratory testing replace executing manual functional tests?

Question: After a feature is delivered, we have recently started to perform exploratory testing on the feature before we execute manual functional tests. We find 95% of the defects during exploratory testing so is it worth while spending the time to write a full suite of manual functional tests if hardly any defects are found from them?
Comment: Did the people doing the manual testing actually find ALL of the same bugs that were found during exploratory testing plus 5% more?  If not then I'd suggest you try another experiment next time, swap the order, do the manual functional tests first, then do the exploratory and see how many bugs you find during exploratory that were NOT found during the manual functional tests.   I say this because the way the question is phrased makes it sound like the manual process resulted in finding all the same bugs that exploratory did and then some, which is not what I would have expected.
Comment: +1 for Chuck's suggestion, which I love.  I am a HUGE proponent of running experiments and capturing data.  Doing so helps people learn a lot.  In the absence of actual data, opinions prevail.  The opinions that prevail often belong to those with the loudest voices and/or are HIPPO's (the Highest Paid Person's Opinion).  Experiment.  A Google search for W. Edwards Deming and PDSA would pull up some interesting articles and blog posts on this topic.
Answer: Do you think you would find the remaining 5% of bugs that are currently found by a suite of manual tests if you spent that time doing exploratory testing instead?  Would managers have the confidence in test coverage that they need to make decisions without those functional tests?
I think the biggest risk of not having a manual functional test suite would be a reduction in coverage so that things might get missed.  However, a "full suite" of manual regression tests might not be necessary to ensure that coverage.  Automated tests are often considered an ideal alternative since they simplify regression testing and save testing time long-term.  They can really free up your exploratory manual testers so they can focus on the most productive forms of testing.
You could also try guided exploratory testing, where testers are given a checklist instead of fully scripted manual tests, and then the testers just make sure they cover the checklist as they perform exploratory testing, in addition to anything else they think is worth trying.  This technique is sometimes called "Guided exploratory testing".  This might be a great alternative for your team since it sounds like you have some very skilled exploratory testers on hand.
Comment: Having well established standards of behavior are great to aid in guided exploratory testing. Some of our users have been using the same system for 17 years now, and they don't appreciate it when someone makes a new screen that's different from all the rest. One could argue that this is not a bug, but simply a violation of the element of least surprise, but regardless of what it's classified as, it's something that if not caught during testing will get reported as a bug. (Even if it gets shot down, it's going to waste some analysts and manager's time.)
Comment: @glowcoder  I'd tend to classify stuff like that as a 'usability' issue (inconsistent UI elements that violates the paradigms that you've used elsewhere make the product harder to use, and not appear uniform and consistent to the user. )
Comment: I like Ethel's answer a lot here..  The only thing I'd add to it is have you tried to figure out why your exploratory testing missed the 5% that it did, and for that matter did it find issues your scripted tests would NOT have found?  I'd be looking at the stuff that was missed, and asking what you can do to improve your exploratory process such that you would have found those missing bugs the next time around.
Comment: liked the idea of "guided exploratory testing"
Answer: My answer assumes you believe you are leveraging exploratory testing as well as you can; in other words, that you do not believe you can discover more than 95% of your defects via exploratory testing.  I think the gist of your question is, "Is it worth the additional work of having a full suite of manual tests in order to uncover the other 5% of defects."
You and your team need to decide whether skipping the additional testing is worth the risk of letting a bug slip through.  When considering the risk, think about the kinds of bugs that might slip through, the frequency of those bugs (i.e. will the circumstances be rare or common?), the severity (when the bug occurs, how detrimental will it be?), and how forgiving you think your customers will be (e.g. high-tech early adopters may be more forgiving than online banking customers).
Aside from that, you need to consider how your customers will perceive your testing process.  In some industries, your testing  process is a private, internal matter.  In other industries, having a well-documented process that is strictly followed is a necessary condition towards achieving a certification.
Finally, how you answer those questions may change over time as your product, organization, and customer base matures.  It may be that today your exploratory testing is enough, but in two years you need to invest the extra effort in a manual test suite.
Comment: The OP asked whether it was worth the trouble to have a full suite of manual tests if they have already done exploratory testing.  The OP also said 5% of their defects did not come from exploratory testing.  My answer was, essentially, "What do you lose if you don't discover that 5%."  No doubt there are more effective and less effective ways to perform exploratory tests, but that wasn't what the OP was asking.  Sorry if it sounded as if I was impugning exploratory testing; that was not my intent.
Comment: I'm not sure how your answer relates to the question - how does additional testing increase the risk of letting a bug slip through?
Comment: Thanks -- I meant to say, "...whether skipping the additional testing is worth the risk...".  I hope that clarifies how my answer relates to the question.
Comment: Ah, ok - yep, that makes more sense to me now. I'd disagree that you're skipping testing though by replacing creating test scripts ahead of time by structured, responsive, exploratory test sessions. I'd like to know a bit more about what you think exploratory testing *is* - it may be that what you're thinking of when you say "ET" is very very different to what I'm thinking of.
Answer: "Is it worth while spending the time to write a full suite of manual functional tests if hardly any defects are found from them?"
That depends - is the purpose of writing them to find defects? If so, then it sounds like you would be better off putting your energy into spending more time testing. If you're considering dropping them, then it doesn't sound like you have any contractual or political obligations to produce them. Manual functional test suites tend to be expensive to produce and expensive to maintain, so unless you have really good reasons for producing that documentation there are probably better ways to spend your money/time.
So what's stopping you?
Some common concerns might be:
1) How do we look at how well we're covering the system with our tests? Isn't there a risk that we'll all end up running the same tests? Or maybe we'll all run the same sort of tests and nobody will think of testing security, or installation?
If this is a concern for you, then one way of approaching this would be to write a set of exploratory test charters instead of test scripts. This article by Michael Kelly gives a good explanation of managing testing with charters, part of a series.
I've also been really enjoying Darren McMillan's blog posts about how he's using mindmapping to plan his testing and record test sessions. I haven't used mindmapping seriously yet for ET myself, but the mindmaps I see other exploratory testers using are just such a lovely clear way of presenting what was covered, and it's much easier to see gaps that remain to be tested.
2) How do we prove what we did?
You don't have to write stuff down before you test, to prove that you tested it. You can write stuff down while you test, and then you can still respond to what you're finding. (Actually, making good notes while you test is a lot more likely to reflect what you really tested than making them before - most scripted testers I've observed frequently went "off-script", so the scripts weren't a good guide to what was tested.)
Here are some good resources/ideas on recording ET sessions:

http://www.quicktestingtips.com/tips/2009/11/template-for-session-notes/
Alternatives to Session Tester for recording exploratory test session results

And here's a great list of general resources about exploratory testing.
Answer: In using "exploratory" testing we've found that it's VERY dependant on the testers experience and understanding of the system. If the tester has a broad knowledge of how the software should work and what should be displayed then they'll be able to catch all those little bugs. The manual process may provide better coverage but might miss an element that should be displayed on an existing report.
Exploratory testing is very good for bringing in external users. Less step by step with the freedom to roam throughout the application. With this being said exploratory isn't the best style when data integrity is involved... just my two bits. Happy testing all!
Answer:
We find 95% of the defects during exploratory testing so isit worth while spending the time to write a full suit of manual functional tests if hardly any defects are found from them???

The fact that you find 95% of the bugs you currently find using one approach is interesting.  But the real questions are:

are you being effective?
Are you finding all the important bugs with this approach?
Are you finding all the important bugs at all?
What do you miss by focusing most/all of your efforts on this one approach?

If I find 100 bugs in total, and I found 95 of them using exploratory testing, but another 100 bugs that I didn't find are subsequently reported after I go into Production, then I have probably failed.
If on the other hand, no bugs are reported after I go into Production, I'd dig in and consider the value of finding the 5 bugs using non-exploratory methods.  I might determine that a bit more exploratory testing would have found them, or that the only way I could have found them was using a different approach.
Answer: What do you do with your scripted manual tests?  If they are just executed by testers once or twice then tossed you probably can change your process & reduce/eliminate the extra paperwork.
But if any one else is using them, then consider the impact outside of QA before elimating them.
Do you have requirements so that the legal department is expecting them to be there?  Or do you do test plan reviews that coders, analysts or others expect & use to help them identify gaps or other issues?  Do some tests get rolled into long term regression meaning someone else may have to pick up writing those?  (And I'm sure there are other things I'm not thinking of.)
Assuming you find & address any downstream impact of changing the process, I'd say less paperwork to write & maintain is usually better.
Comment: Good point on considering other users of the documentation.
Comment: Yes, good comment.  I've worked in industries where the test cases are actually a deliverable to our customer. Sometimes you have to write the tests anyway.  In this context, I've used exploratory testing to find the problems early & efficiently, then ran the formal/written test cases for "score".
Answer: Exploratory tests can help to plan and write an effective functional test suite. When we are  required to test a new feature it is always better to explore it before planning or automating it. Exploratory testing can generate new testing ideas/path and can reveal uncovered areas for testing as we explore the software.
As Ethel Evans said with automation we can better track the test coverage.
Moreover automation is cheaper than manual testing. Hence exploratory testing should be used to complement the running of functional test suite and not replace it.
Comment: Heh. Unfortunately it's perfectly possible to make automation MORE expensive than manual testing, if you're determined enough.
Comment: Sorry I couldn't understand your point, automation usually has lower costs associated with it compared to manual. It saves us cost in terms of time and human intervention, fatigue etc. Please explain how it could be costlier
Comment: Well, if your automation has lower costs, you're probably doing it right! Sorry, should have been clearer - I think it's worth pointing out that in order to save money and time, automation needs to be done well. If done very badly, it can be more expensive. (E.g. I have seen an expensive test tool where over more than a year, only 8 tests had been written. Think of the licence fees! I could have run those tests in a day, manually.)
Comment: For functional testing, creating well done (non brittle, low maintenance automation is generally more expensive than executing the same test manually, often my several multiples.   However, once it is created, it's very cheap to run, so run it often if you have it.  IOW not cheap to create, but very cheap to use.  (the exception being combinatorial esting, where even creating disposable quick and dirty automation beats doing the same thing with small variations thousands of times)
Answer: In this case, you can regularly go through the manual functional test suite, let's say every other release cycle or once a month, and deprecate the not-so critical Test Cases.  Keeping the manual functional test suite well groomed, you can make sure that they only test the critical scenarios.  This will save you time and make sure that the code does not go in production with the bugs in critical components that should have been very obvious find had you run the functional test.
Based on how regularly you groom your test suite, it should take minimal time relatively.
Answer: Manual and exploratory are two different things but together can make huge difference to the testing. Both things comes into picture when time is the factor, so if you have time then scripted manual testing is good option but when time is less then exploratory testing is obvious a good choice.
Comment: Did you intend to say that if there's time testers should use scripted testing *instead of* exploratory testing? I'd have to disagree if that was what you meant.
Comment: Can you clarify what you are intending to say?
Answer: Exploratory and Manual testing are not mutually exclusive, you probably mean scripted regression vs. exploratory.
Comment: You have a good point, perhaps it's worth expanding on it a bit? Especially if the author of the question doesn't understand?


If there was another realm full of magical beings, how would they cover it up to the general population?

Question: I'm writing a story in which witches from the "higher realm" visit the "lower realm" (Earth) with a consistent frequency. However, most of, us mortals do not know it. How can I accomplish such a cover up, and why would it even be necessary to cover up in the first place?
Answer:
why would it even be neccesary to cover up in the first place?

See:

Salem Witch Trials
Early modern witch trials: "An estimated total of 40,000-60,000 people were executed during the witch trials."
Modern witch-hunts: "While an unknown problem in vast parts of the Western population, body-counts of modern witch-hunts by far exceed those of early-modern witch-hunting."

I'm writing a story in which witches from the "higher realm" visit the
  "lower realm" (earth) with a consistant frequency. However, (most of)
  us mortals do not know it. How can I acomplish such a cover up

The usual conceit is that: (1) witches can "pass" for human, (2) they refrain from using their powers when mundane people who can't be trusted are able to observe them as a universal code of ethics, (3) they self-enforce the code of secrecy if it is violated, and (4) they use whatever measures are necessary, including brain washing by magic, to insure that unreliable muggles are prevented from sharing their experiences with others in a way that will be taken seriously.
This is the approach taken in at least 90%+ of the contemporary fantasy genre (in all fictional media), and also in kindred genres such as those involving aliens (see, e.g., the TV series Roswell and V, and the movie series Men in Black), gods and demigods in a modern setting, and those involving fairies, angels, demons, replicants, androids, superheroes, psychics and mutants.
The first element ("passing" for humans) often takes some additional effort on the part of the non-humans. One decent example of a case where some serious effort is necessary for witches to "pass" as human is The Witches (1983) by Roald Dahl, in which a hidden corps of witches among humans has to engage in some previous serious (basically non-magical) efforts to disguise themselves to go unnoticed. Elaborate non-magical disguises were also commonplace in Men in Black. In Stephanie Meyer's novel The Host, the non-humans hid inside human beings. In the modern reboot of Battlestar Galactica the robots posing as humans were carefully modeled to look like humans. In the case of much of the fiction involving fairies, the fey use what is usually called a "glamour" to conceal their appearance to the average human's mind.
Comment: And Harry Potter.  And X-Men.  And "Bewitched", "My Favorite Martian", "Third Rock from the Sun", and "Mork and Mindy". etc...
Comment: For reasons, also see the Spanish inquistion etc. To be honest, nearly all religious purges would count witches as heretics.
Answer: If you can get your hands on an old copy of Stalking The Night Fantastic, a role playing game from the 80's, you will find it immensely helpful.  It is basically a users guide for a new recruit to a secret organization, Bureau 13.  That organization is charged by the governments of our world with a singular mission, to hide all supernatural denizens and their activities from the mundanes.
From subterfuge techniques to a list of infiltrated sups who live among the mundanes and can be of great help to Bureau's goals, that game manual has everything you need to defend your visitors from the higher realms.
Answer: The first question you need to ask yourself is "who is covering it up?"
Either the higher realm wants to remain secret and as such keeps it's members in line or someone on Earth wants it to remain secret.
The higher realm may want to keep it secret because humans are pretty violent and xenophobic. If human found that there were super powered creatures living among them operating in secret, they would hunt them down. If the higher realm felt that they would lose such a fight, they would try to keep their existence a secret.
The Dresden Files by Jim Butcher uses this idea. Vampires, witches, fairies etc all exist but use magic to hide from humans. While humans are weaker than them, there are so many humans with so many weapons they fear humans hunting them down.
The other option is someone on Earth want them to be a secret. If magic actually exists and powerful beings on other planes of existence actually exist then the possibility of "doing a deal with the devil" becomes an actual possibility. The church and/or government would want it to remain a secret so people don't go looking in places they shouldn't. They would employ agents to hunt down threats and silence witnesses by any means possible.
Monster Hunter International by Larry Correia operates like this. Dark forces gain power from human belief so the less people know, the less powerful the forces are. The governments of the world have their own agents to hunt down threats and silence witnesses but they also pay private contractors bounty for every monster they kill.
Answer:
How can I accomplish such a cover up,

Misdirection.  Clearly people are aware witches exist, and there are witch hunters.  So expend some efforts making sure what they're looking for isn't what witches actually are.
Publish stories about witches as warty old ladies riding brooms, vulnerable to fire or water.  Convince witch hunters to look for certain marks and paraphanalia as sure fire signs.  Scam bored housewives into reviving a pagan religion.

and why would it even be necessary to cover up in the first place?

Make the witches feel vulnerable in the lower realm.
They come for a reason, but are still out of their familiar environment, and maybe they can only 'cross over' at a certain time of year*.  There are so many mundanes with their strange devices, any of whom could be or become witchhunters, which are at least annoying to deal with.  Maybe there is also only so much mana to draw on for protection, and using it up is flashy (or spooky), and that only ever makes things worse.  Perhaps there is actually even some form of witchbane.  The best defence against fanatical witchhunters is thus not to attract attention.

$^*$ Easter - that other time is pure misdirection.