What to do when a user persistently posts unsourced opinions as answers

Question: Mi Yodeya works very well as a motley crew of advanced Shas learners, regular run-of-the-mill Torah students, and even complete beginners such as myself. What do we do, though, when a user with wonderful intentions but a middling or even lower knowledge base starts posting unsourced opinions as answers on a pretty regular basis?
Answer: Give feedback. This is why votes and comments exist.
More specifically, diagnose whatever the problem is (unsourced opinions in this case) and offer a possible solution if the answer can be fixed.
To quote someone else on a recent answer as an example:

A source would greatly improve this.

And myself on a different recent answer:

In this answer you quote Maimonides, the ancient rabbis around 70 CE, Abravanel, and the Midrash, but you don't provide references for any of them. It's hard to evaluate the correctness or quality of the answer without knowing your sources

I think that if the author edited the answer corresponding to comments like those, the answer would no longer be problematic.
This doesn't mean that the user would necessarily fix previous posts or post better answers in the future, but there is really nothing else to do. Users can be suspended by moderators, but I don't think that writing bad answers alone should be enough to warrant that.
Comment: @josh if you downvote 500 deserving answers I'll recompensate you with a 500 pt bounty
Comment: @JoshK As silly as it sounds, I agree and also find it annoying that I lose a point every time I downvote. I find that means that I limit my downvotes to things that egregiously erroneous/borderline (or way past the borderline) heretical. There are quite a few 'wrong' answers that I see which I don't want to downvote due to the 'hit' to y own reutation, as silly as that is. And somehow I'm still finding (almost daily) posts that I feel 'warrant' a downvote.
Comment: Excellent advice, thank you  @b a. I suppose the underlying issue is that I resent having to sacrifice a point of reputation every time I downvote. Completely agree suspension is not warranted in this case.
Comment: Neither one of us is lacking in reputation points, @Salmonius, it's a silly psychological reaction. And yet...
Comment: @JoshK in fact, I'll also give you the 500 back, so you'll have incentive to downvote bad posts...
Comment: @JoshK comment here with the 500 links and I'll pick a post of yours to bounty. Same to anyone else. (If I trust you I'll consider waiving the link listing and revert to honors system)
Comment: I'm honored you trust my judgement to that extent, @Double AA
Comment: How exactly would this work,  רבותי? (@Double AA & @רבות מחשבות )
Answer: This is not necessarily a problem (in my unsourced opinion).
Consider the following possibilities:

You don't trust me to answer a question on my own but you do trust me to apply a  source from one case to another?
You don't trust me to apply a source from one case to another but you do trust me to accurately summarize what a source actually says?
You don't trust me to accurately summarize what a source actually says but you do trust me to translate a source?
You don't trust me to translate a source but you do trust me that a translation I quote is an authoritative translation?
You don't trust me to quote an authoritative translation but you do trust me to quote someone authoritative certifying a translation as authoritative?

Where does it end? At some point you either have to trust me, or better yet, have to be somewhat skeptical of everything I say. Just like you should be skeptical if I say "There is a commandment of hearing Shofar" you should be skeptical if I say "Maimonides states that there is a commandment to hear the Shofar". Again, you should be skeptical if I say "Maimonides states in Hilchot Shofar 1:1 that there is a commandment to hear the Shofar", and you should still be skeptical if I say "Maimonides states in Hilchot Shofar 1:1 that there is a commandment to hear the Shofar: מצות עשה של תורה לשמוע תרועת השופר בראש השנה". And you should be skeptical if I say "Maimonides writes: מצות עשה של תורה לשמוע תרועת השופר בראש השנה - there is a positive command of the Torah to hear the blast of the Shofar on Rosh Hashanah (my translation)".
In all of these cases you should check to the best of your ability to make sure that what I'm saying is correct. Your method of checking might be to consult someone else's translation, read the original passage, see what other users have commented or voted, etc. You should never accept something just because I claimed it.
Looked at in this light, there is not much difference between a sourced answer and an unsourced opinion. In the former you have to make sure that my answer accurately represents the source, and in the latter you have to check that my answer accurately represents Judaism. In either case, if what I wrote seems wrong you should downvote it and leave a comment explaining the problem.
Of course, answerers should as much as possible let readers know which parts of an answer need to be checked the most (e.g. by saying "this is my own application from one case to another"), but as long as an unsourced answer doesn't pretend to be an authoritative statement I don't see anything wrong with it.
Comment: But a sourced answer is somewhat easier to look into: you know where to look. (Of course, you still don't know whether the answerer accurately picked it as the right place to look. But still.)
Comment: None of this addresses the aspect of the question that focused on the user: what to do about a _user_ who consistently answers unsourcedly.
Comment: https://judaism.meta.stackexchange.com/a/3684/759
Comment: @Alex Whether there's a problem that needs to be addressed at the user-behavior-pattern level depends on the volume.
Comment: If you misapply a source text, I can counter that, "No, Rashi does not state that Tehillim 90:5 "Shouvu benei adam" is actually a reference to people going back for thirds at the kosher Chinese buffet spot in Great Neck,  rather, he ties it to repentence". If you simply state an incorrect opinon with no backup, "Some rabbis in ancient times said that we can just skip the story of Yosef in Egypt", what can I say to that?
Comment: The issue is not whether posts' assertions are correct or not. It's whether posts are useful or not. Note the tooltips for upvoting and downvoting. Assertions of personal opinion, by themselves, generally provide very little value to readers and are therefore generally not good additions to our repository of Judaism Q&A. It is worthwhile to try to educate users and guide them toward providing more valuable posts and fewer value-less ones, in the interest of maximizing both the value-to-noise ratio of our content and the happiness of community-members in the community.
Comment: @JoshK How do you know it's incorrect? If you know everything that every ancient rabbi said then you can downvote and leave a comment saying that you know that no ancient rabbis said that. If you don't know what every ancient rabbi said then you can ask the answerer to be more specific so that you will better be able to evaluate the claim.
Comment: @IsaacMoses My point is that I don't think this is a major problem that we need to "do something" about. If a post is not useful it can be  ignored or downvoted. You can always comment if you think an answer is wrong, and you can always point out that sources would make an answer more useful. There are also some instances where sourceless answers are apparently useful (e.g. [here](https://judaism.stackexchange.com/a/105562/13438) where it's highly upvoted and accepted).


What are the main differences between machine learning and classic approaches to natural language processing problems?

Question: What types of NLP problems are best suited to machine learning and which are best solved by more classical approaches (e.g. syntactic and semantic analysis?)
Comment: Machine learning deals with models, as opposed to theories of natural language.  On the difference between model and theory, see Braithwaite's book **The Nature of Scientific Explanation**.
Comment: Well, you can start here -- [this was the state of the art 15 years ago](http://www.umich.edu/~jlawler/routledge/book-7.pdf) in both of those areas. But a lot has happened since.
Answer: The major dichotomy in NLP is that of rules-based approaches vs statistical approaches.
(Machine learning is used in some statistical approaches.  Given the timeframe of the development of the field, the earliest statistical approaches, for example those of SMT pioneers, surely can or will be seen as classical.)
Rules-based approaches are basically the obvious or naive approach - hand-tweaked heuristics.  They require linguist experts for every language launched, they are hard to bring to full coverage, and as coverage increases so does complexity.  They are inherently static (which is a drawback in a world where the probability of the parse of the photo caption Nice truck attack changes in real time).
Statistical approaches are better suited to open-ended problems, but they require initial investment and plenty of data, and people who understand the principles of linguistics and statistics (and software).  They can update as the data update or with humans in the loop.  But as they always produce results they can produce surprising results, for one they trained on imperfect data, and not all machine learning systems make explainable or even deterministic decisions.
The attractiveness of statistical approaches has followed the steady growth in problems, data, CPU and connectivity.  In practice today's production systems use a (often messy) hybrid of rules-based and statistical approaches.  For example a search feature may be use rules-based filtering, but statistical ranking, with ad hoc boosts and blacklists.
So the decision of which approach to use is only partly a function of the problem type.  Just as important are the goals, scope, data and so on.  At another extreme there is even the human-backed approach - a human pretending to be a machine pretending to be a human - which has high accuracy, high latency and high cash burn.
Answer: Machine learning tends to produce results, that look impressive but cannot be tracked by humans. A statistical machine learning algorithm may have really good scores at some classification task, but when you analyse how it comes to its conclusion, it uses a% of feature_1, b% of feature_2 and so on to base its decision on.
Classical approaches select features humans can recognise and describe easily, and base their decision on only one or a few of them. Machines use several dozens of features that are easy to compute (e.g. frequency counts, a hard task for a human) and base their decisions on many of them.
Comment: This is very inaccurate. The first sentence is wildly misleading.


Incorporating fruits in creme brulee

Question: Does anyone have any idea on what precautions to take while combining fruit puree with custard for creme brulees? I added strawberry puree ( which I added some lemon juice to) to my custard and it split the custard while baking. I'm guessing the lemon was the culprit but can strawberries split cream/custard too? If I wanted a strong strawberry flavor through my creme brulee how could I go about achieving that?
Comment: related: Spanish [Crema Catalana](https://en.wikipedia.org/wiki/Cr%C3%A8me_br%C3%BBl%C3%A9e#Crema_catalana) is very similar to Creme Brulee, but typically flavoured with citrus *zest* or [even whole slices of peel](https://spanishsabores.com/2016/01/25/homemade-spanish-crema-catalana-recipe/), which has the flavour without a lot of water-based liquid or being acidic.  Won't help with strawberry, though, so not posting as an answer.  (And there's already an answer proposing a flavour extract instead of whole fruit)
Answer: This is a tough question. Fresh fruit puree is very unsuitable for incorporating in custards if you want a strong flavor. It contains tons of water, and dilutes your creme brulee a lot, and also brings the pH balance out of whack, interfering with the setting. You can only incorporate small amounts for color and a hint of flavor. Don't forget to add sugar to the puree when you are doing this, it strengthens the fruit flavor perception and reduces the negative effects on texture.
If you want a strong flavor, here are your options when having access to normal kitchen equipment, in order of closeness to the ideal of getting real strawberry flavor into otherwise typically-textured creme brulee:

Purchase strawberry aroma and use it. Don't forget to color the creme brulee, either with food coloring or with small amounts of puree.
Use freeze dried strawberry powder. You might have difficulty finding the real thing (pure strawberry juice freeze-dried) as opposed to maltodextrin-based powders, read the description carefully. An alternative is to grind strawberries which you have dehydrated yourself, but that will give you inferior results.
Cook down your own strawberry simple syrup and use that. This works with any fruit. Start with pressing juice of an amount roughly equal to your dairy base - if your recipe uses 350 ml of cream and 150 ml of milk, you need 500 ml of strawberry juice. Depending on your juicer, this will need 1.5 - 2 kg of strawberries. Make the juice, then add sugar at 1:3 ratio (so 165 g sugar for 500 g of juice). Cook on a low flame until a candy thermometer shows 104 Celsius. Let it cool to room temperature before using in the creme brulee. Quick alternative with somewhat worse taste: use a store bought jam, preferably a smooth spread without chunks.
Use liqueur. This is usually done with other fruits where there are traditional brands of liqueur, such as cassis, grand marnier or frangelico. But if you can find a good strawberry liqueur, try that. Alcohol is a great flavor carrier and will give you aromas you can't get from cooked down or dehydrated fruit. For best results, combine the alcohol with one of the other solutions here.
Instead of putting the flavor agent within the custard, go the traditional route and pour a fruit sauce over it. You can use the reduction from the previous point for that, or make it in some other way.
Again, instead of flavoring the custard itself, pour it over whole strawberries in the mold. This works better with poured custards or puddings rather than creme brulee, since the strawberries won't take kindly to baking.
Instead of making creme brulee, make a strawberry sabayon, using fruit puree or fruit juice as the liquid to be thickened by the yolks. This dessert has a strong fruity flavor, but a very different texture, and it also brings out the egginess of the egg yolks.

As an aside, these methods are useful beyond creme brulee, you have the same options for all creamy desserts (including panna cotas, starch puddings, cheese based cremes) and many types of cake icing, especially buttercreams.
Comment: If the problem is the liquid, you could maybe use dehydrated heavy cream power and re-hydrate it using pureed strawberry for part of the liquid, so that your overall liquid is the same amount. I haven't actually cooked with the heavy cream powder, but it's supposed to be the same.
Comment: @user3067860 I love the suggestion too, and I think it deserves its own answer. I have powdered cream at home, and while it does produce a different texture (grainier), it is an acceptable substitute in many dishes if one doesn't need perfection. I will try to find the time to test it. Just have to see which fruit, since strawberries are not in season here, and I don't want to use something too acidic like citrust fruits.
Comment: How about dehydrated strawberries in an oven?
Comment: @data it can be done, but will give you less taste and worse texture than freeze dried powder. It is a good point, I will update the answer.
Comment: @rumtscho, good point, didn't think about the taste not being "fresh" - it would be more like jam.
Comment: @user3067860, what an interesting suggestion
Comment: @rumtscho Please post if you try it, I'm hesitant to since I haven't cooked with it like that!
Answer: I've successfully cooked Creme Brulée with whole raspberries at the bottom. Perhaps you could use a similar strategy, e.g. put in halved strawberries (perhaps with the cut face against the bottom of the bowl to minimise interaction). Whole fruit will minimise altering the pH or water content provided it doesn't disintegrate. You could combine this with some strawberry aroma in the custard itself.
Answer: My favourite solution to the problem is to infuse the cream with a Strawberry (or any flavour) tea (well technically infusion)
Here is the one I used but I suspect any would do. Just infuse overnight in the fridge and then strain after you have heated the cream .
Answer: Try an approach that often is used when making posset! First, cook cream and sugar (similar measurements as in a creme brulee), then pour a spoonful or two of the cream-sugar mixture into the strawberry pure and stir thoroughly. This should neutralize a fair share of the acidity that causes splitting. Then pour the strawberry puree in the cream, and stir thoroughly.
You could possibly whip the egg yolks separately with some sugar to help you obtain the desired texture, then slowly incorporate the cream into the yolks and then go on as usual with the creme brulee.
I am not promising anything, but this might work?

Incorporating fruits in creme brulee


How to check if all drivers are up-to-date

Question: Is there a way to check if all installed drivers are the correct/best ones and if they are up-to-date? Background of my question: I have installed Windows 7 on a Notebook (2006). The manufacturer of that Notebook says that Windows 7 is not supported. Nevertheless, it is running :-) Unfortunately, it is not really stable: once a day I get a blue screen. I guess that I do not have the best fitting drivers and in the device manager of Windows there are two entries "Basic device" with a warning mark beside them... so can I do a "select all and check for driver updates" somehow?
Comment: As a general rule, most drivers written for Vista will run in 7. Not all, but most - so, as long as they support Vista... I have no idea how you could check for updates, though.
Answer: Try running a driver tool like driver identifier, will tell you if some driver has an update ...
Answer: I have had some success with SlimDrivers - it's pretty widely available at reputable sites and gets reasonable reviews. It will try and install toolbars and other rubbish but you can opt out of these during the install. I normally install this as required, run it a few times and then uninstall when finished. It does backup any changes so don't uninstall until you have verified everything working ok.
Answer: There is many general/all-in-one tools that try to find and install driver updates, personally I do not recommend these. However if manufacturer has it's own tool it may (or may not) properly install drivers.
At least tools provided by IBM & Lenovo works reasonably well, in most cases all drivers updated. HP also has own update tool but my experience is that in most case it will not update or install anything. Others also provide their own tools but I think that I dont have enough experience with others to say if those are good or not.
Also there is update tools provided by component/ic/expansion card manufacturers including intel and nvidia.


Can I force evolution in a group of cells by removing all the smaller cells?

Question: I actually have algae growing in water in a container. I was thinking if it was possible to filter the water so that all the small cells will be filtered out and only the bigger ones will remain to reproduce cells that tend to be bigger.
Is that possible?
What type of filter should I use?
Comment: Wouldn't this actually be artificial selection?
Comment: A formal showing of your 'selection pressure' might also require proof that your initial algae population consists of only 1 type of algae.
Comment: @evamvid which is a form of evolution.
Answer: Short answer
Yes that would work in the condition that the trait you select for (size) is heritable.
Long answer
The kind of selection you would apply is called truncated selection because you fix a limit in size (depends on your filter) under which individuals do not survive and above which individuals survive and reproduce equally.
The response to selection ($R$) is given by the breeder's equation:
$R = h_N S$
, where $S$ is the selection you apply. In your case, $S$ is the difference between the mean size of the parent generations and the mean size of those you allow to reproduce in the parent generations. $h_N$ is the heritability (more info in additional info).
So, if you measure the mean size of your cells, filter them, measure their size again (or infer their size based on previous measurement and the size of you filter) and calculate the difference between the two measurements you get $S$. Then you let your filtered individuals to reproduce and you measure the size of their offspring which is $R$. By dividing $R$ by $S$ you get the heritability $h_N$. If you do not observe any difference in size between your two generations it means that the heritability is 0 ($\space h_N = 0\space$). Of course, you'll need a population that is composed of enough cells in order to have a good estimate.
Additional info
To be a bit more accurate $h_N$ is the heritability in the narrow sense. It represents the part of variance in the population that has to be accounted to additive genetic variance. The word additive genetic variance might seem obscure. In other words
$$h_N = \frac{V_{Ga}}{V_{P}} = \frac{V_{Ga}}{V_{G}+V_{E}} =  \frac{V_{Ga}}{V_{Ga} + V_{Gd}+V_{E}}$$
, where $V_{GA}$ is the additive genetic variance, $V_{GD}$ is the dominance genetic variance, $V_E$ is the variance due to environmental variance and $V_P$ is the total variance (phenotypic variance)
Hope that helps. Do not hesitate to ask further question if something is unclear or if I missed one of your point.
Edit
Filter
The filter you need should allow you to discriminate the cells based on their size. Therefore, it should be relatively accurate. It is common to classify the phytoplankton based on their size, see this. You should try different filters and see what filter allows a good discrimination.
EDIT
I assumed your cells were all of the same species. Is it the case? If you just sampled them from a lake and let them grow in a container then you very probably have various species. Therefore, you would select (based on their size) for species with your filter rather than selecting individuals within a species (based on their size again). It is kind of the same process anyway and the breeder's equation still holds.
Comment: thanks for the very helpful answer. can you tell me what filter i can use?
Comment: @SumitSingh See my updated answer.
Comment: I just saw your edit re single species after I had commented the question.  OP sounds like a fun science project, if it can be performed accurately!
Answer: I think one would not have a lot of success using a filter to do this, rather using a centrifugal gradient and comparing the fractions to a standard I think would be preferable. Nitrocellulose filters are made with precision but not very astounding accuracy which is the main reason they are commonly used at set sizes (like 0.2 and 0.4 microns) and not often in between. Good question though


How do I determine the VFR pattern altitude at an airport?

Question: How do I determine the VFR pattern altitude at an airport? Can I find it on a sectional?
Answer: In April 2013, the FAA's Charting Group met to discuss this question.  The standard pattern used to be 800 ft AGL, and the Chart Supplement (formerly called Airport/Facility Directory or A/FD) was inconsistent in listing them.  Ultimately they decided:

Chris Criswell, AJV-22, reported that, per ACF recommendation, all traffic pattern altitudes, standard and non-standard, will be added into NASR (the AFD) for all airports. This will be a day forward implementation beginning in July 2014.

Some other places the TPA is recommended to be 1000 feet AGL:
Advisory_Circular AC90-66A

c. It is recommended that airplanes observe a 1000 foot above ground
  level (AGL) traffic pattern altitude. Large and turbine powered
  airplanes should enter the traffic pattern at an altitude of 1,500
  feet AGL or 500 feet above the established pattern altitude. A pilot
  may vary the size of the traffic pattern depending on the aircraft's
  performance characteristics.

The Chart Supplement (A/FD) will typically list the Traffic Pattern Altitude (TPA) if it is non-standard (not 1000 ft/1500 ft AGL)
The FAA's Airplane Flying Handbook says

The traffic pattern altitude is usually 1,000 feet above the elevation of the airport.

Now the Chart Supplement (A/FD) will be the definitive guide!
Comment: @flyingfisch no I think it would be 1000 ft AGL. Everything *used to* be 800 AGL, but as you can see from AC90-66A and the AFH, if unpublished, it's recommended to do a 1000 ft AGL TPA, which would be 2067 MSL for KAKR.
Comment: Hmm, I can't seem to find [KAKR's TPA](http://aeronav.faa.gov/afd/18SEP2014/ec_231_18SEP2014.pdf). Would that mean it is 800ft AGL?
Comment: Ah ok, understood. thank you :)
Answer: No, it's not on a sectional. The Traffic Pattern Altitude (TPA) can be found in your A/FD.
Edit: I just double-checked and it's not on all airports in the A/FD. I would assume that if it's not listed it's 1000' AGL, but not sure why it's listed on some and not others. When it is there it'll be on the 2nd line after fuel. It'll look something like this: TPA-1072(1000)
Answer: In the UK, this information can be found in the AIS under Aerodrome information - specific and is not printed in charts.
The section on "Flight Procedures" for my local field specifies

Circuits
  (a) Standard overhead join. Variable circuits. Fixed wing circuit height 1000 ft QFE.
Answer: For a non-standard traffic pattern altitude, you will be provided an altitude, and if it's a standard traffic pattern altitude (1000' agl), then it will not display an altitude or it will be blank as I've seen before.
e.g. KMBS does not display an altitude but TPA is 1000' agl


need help in EJB stateless beans

Question: I am new to EJB. I have a requirement of calling a method of remote stateless bean and setting a value, before calling any method on the same bean. The value set from first method call should be available to second method. I know that a stateless bean can't hold instance variables values for next calls. Is there any alternative to make the value available to the bean method without making bean as stateful bean. any tweaking tip?
Answer:
Is there any alternative to make the value available to the bean method without making bean as stateful bean?

Without passing the value to the second method or persisting it, for example in database, I don't think so (using an instance variables is certainly not a solution as you're not sure to call the same session bean with each method call because the pool can return any session bean for your method call).
Answer: It is a wrong use of stateless session bean. Stateless should depend upon only the parameters that are being passed to it and no other previous state. Even if you put a hack around it, think of poor guys who will support it later.
Database is definitely a better way of doing it. Otherwise, can you use interceptors ? They are powerful in EJB 3.0 and can even change the parameters, set some value etc.

need help in EJB stateless beans


Can frozen peaches be made into jam or other things?

Question: I have over ripe peaches.  I have scaled them and pitted them and they are in lemon water.

Can I freeze them to make jam later?
Can I put them in the refrigerator to make jam later?
Answer: You absolutely can make jam from frozen fruit.
Freezing is like "stopping time" (or at least slowing it down almost to a stop) for the frozen food. Freezing water breaks cell walls, that's why thawed fruit is mushy, but so does boiling when making jam, so no problem at all here. You can also freeze leftover fruit before it spoils and combine various fruits in your jam or make flavour pairings with fruits that are in season at different times.
You can either puree your fruit and freeze it in a ziplock bag or flat container or freeze chunks on a tray, then transfer to bags. Good wrapping is essential, as with all frozen foods.

Personally, I often freeze puree because a) it needs less freezer space and b) we prefer smooth jam. I pre-meassure one batch and cook the jam when I have time.
Freezing individual pieces, on the other hand, has the benefit that you can choose later how much fruit you need for a recipe. This is also good if you haven't decided about your recipe yet or love to combine flavours. These pieces are also usable for other dishes.

Storing your prepared fruit in the refrigerator is not without risk. Overripe fruit spoils quickly, even in the refrigerator and "later" quickly can become "too late". So unless you are absolutely sure that you will cook them tomorrow and they have no "dubious" (e.g. mushy, about to get moldy) spots, just freeze them.
Answer: I don't know about jam specifically, but yes to other things.  The standard thing would be to freeze them, and then use them for smoothies, but you can also use them for instant sorbet if you have a food processor:

2 cups of frozen fruit
1/4 tsp of xanthan gum
a cup or two of fruit juice
maybe some syrup or extra sugar

Put the fruit into the food processor, and pulse until you've gotten it all down to small bits.  (everything under about 1cm (3/8")).  Add the xanthan, pulse to mix a couple of times, then turn it on and pour in the fruit juice.  Add more 'til you get to the consistency you like.  Taste it.  If it's not sweet enough, add some sugar (heavy syrup works best, but I've tossed in powdered sugar or superfine sugar ... regular granulated might work) and then blend again.
If you take it past what you'd like in consistency, just set it in the freezer for an hour or two.


How to set up SSH access without a valid internet IP?

Question: I want to allow other people to ssh into my Mac via login and password, but it does not have a valid internet IP.
How to allow people to ssh when the machine might be at home, in an office, or coffee shop?
Answer: You need a valid IP somewhere.
If this IP is not static, you can advertise it through dyn.com as suggested by other answer.
Behind the valid IP :
you'll need a computer to run a VPN server.
On your Mac :
connect (automatically ?) to the VPN, so that other peoples will be able to "see" you.
For other people to connect :
They'll need an access to the VPN server, addressing it through its static IP or its dyn.com hostname.
Then they can connect to your ssh.
This won't be easy to set-up, but I don't see another answer.
Advertising the IP of your Mac won't be enough because this will just allow other people to see the IP of the router which grants you internet access. But this router will not forward its ssh port 22 to yours.
Answer: You would need to use a service like dyn.com or afraid.org to provide a dynamic DNS name to the IP address your laptop gets. Many of these services offer a client program to update the dynamic DNS listing when the computer gets a new public-facing IP address (such as when your home internet IP lease refreshes)
Answer: And here it comes a much simpler solution:
http://sf.net/p/pigterm
I just released this opensource project which:
Helps you connect to your Linux terminal far away without Valid IP, VPN, dyn.com account, etc. All you need to have is a pair of Jabber chatting accounts. You run the software in your Linux server, it connects using its jabber account and waits for you. You run the software again at home with another jabber account and start chatting with your server. Two computers will see each other and will start communicating. All the communications are encrypted.
This image here shows more detail on how:
http://sourceforge.net/p/pigterm/wiki/PigTerm%20Home/attachment/Howitworks.png


Chess software that enables you to set up a position from scratch?

Question: I'm looking for chess software (free or otherwise) that will allow me to completely clear the board and set it up as I wish in order to analyze a specific situation. All of the chess puzzle software I've seen seems to have only pre-loaded positions to solve.
Comment: Thanks for the quick response. I'm getting back into playing and not familiar with what's out there now for software.
Comment: The screenshot is of ChessBase 15. Actually, that feature has not changed since ChessBase 1 back in 1990. ChessBase is the leader, and granddaddy, of chess software.
Comment: What about lichess.org https://lichess.org/editor?
Answer: You don't mention what platform you are using, but on Android I use the "Analyze This" app - it lets you set up positions from scratch, and also use an engine to analyze.  There is a free version of the app, and a paid "Pro" version.  In the free version, the only available engine is Stockfish; in the "Pro" version, you can add other UCI engines.
Answer: ChessBase, or even the lesser priced Fritz, allow you to do that. Just open a board, and type in "S", and it will let you put in whatever position you want. (They both allow you to then analyze from there.)
Answer: Most general-purpose chess software has this feature, usually under "Edit Board" or similar menu entries.
On Linux, usually there are two components to the software which are developed independently - a board program and a playing engine; the latter acts as an opponent or an analyser.  The board program, such as Scid or Xboard, is where you would look for the board setup functions.
On Windows, the popular chess engines usually come with their own board front-ends.  Crafty is a decent free option.
It's also possible to use an online browser-based platform such as LiChess.
Answer: Lichess as a website - as mentioned by Chromatix - offers the Board editor online and in the app. Lichess is free software.


PCI onsite QSA Audit Review

Question: Has anyone had any success using video recordings from ObserveIT during a PCI  onsite QSA audit review?  We are scheduled to be audited in a few months and are considering adding ObserveIT to guarantee coverage of anything missing. Is this a good expectation?
Answer: You should be asking this question directly to your QSA as they will be determining what they accept as evidence for your compliance. The PCI Council does not necessarily bless or damn any particular application, if you find a tool that will help you easily manage or address a requirement, and its cost effective and accepted by the QSA, you'd have a win.

PCI onsite QSA Audit Review


What is the consequence for breaking a promise made in the name of Allah?

Question: I sometimes find myself wasting time on the computer, or watching movies when I have work to do. What I do then is swear in Allah's name that until a task is done (some tasks take a few months) that I won't waste my time doing these things. It used to work perfectly; however, I don't know how I started breaking these promises, but I did and I want to know: what's the consequence? I think I heard somewhere that you have to fast three days or something, but I figured I would come here and get a clearer answer.
Comment: Related: [What should I do if I accidentally swear to do something bad out of anger?](http://islam.stackexchange.com/questions/1079/what-should-i-do-if-i-accidentally-swear-to-do-something-bad-out-of-anger)
Answer: The compensation/expiation of breaking an oath is clearly stated in this ayah of the Holy Qur'an.

Al-Ma`idah (Ayah 89):
Allah will not impose blame upon you for what is meaningless in your oaths, but He will impose blame upon you for [breaking] what you intended of oaths. So its expiation is the feeding of ten needy people from the average of that which you feed your [own] families or clothing them or the freeing of a slave. But whoever cannot find [or afford it] - then a fast of three days [is required]. That is the expiation for oaths when you have sworn. But guard your oaths. Thus does Allah make clear to you His verses that you may be grateful.

It is not acceptable of a muslim to break promises all the time.

Sahih al-Bukhari :: Book 1 :: Volume 2 :: Hadith 32
(and many similar ahadith)
Narrated by Abu Huraira:
The Prophet said, "The signs of a hypocrite are three:

Whenever he speaks, he tells a lie.
Whenever he promises, he always breaks it (his promise).
If you trust him, he proves to be dishonest. (If you keep something as a trust with him, he will not return it.)"

ۚ  وَاللَّهُ عَلِيمٌ حَكِيمٌ (And Allah is the All-Knower, the Wise)
جزاك اللهُ
Comment: Your interpretation of the hadith is exaggerated, as it may happen that one can't fulfil a promise the issue is once it gets to the point of being like a habit.


Origin of the word "mainframe"?

Question: What might be the origin of the word "mainframe" for describing a type of computer?
Comment: Web search does not turn up a specific first use or earliest reference.
Comment: Voting to close as a general reference question that could be found easily in a quick web search.
Answer: The word is formed (obviously) from the adjective main applied to frame, which tends to coalesce into mainframe in any context where a particular main frame becomes a standard component and needs a noun for convenient reference.  For example, the term was used for the main frames of locomotives and early automobiles.  A particularly relevant such use is in telephone infrastructure, where there was a large frame used for an exchange, holding wiring and relays for a group of phone lines with a common prefix.  For instance,  in this 1918 article, the diagram has an arrow labeled "to new exchange mainframe".
Early computers used a large frame (much larger than "racks" used now) to hold wiring and components for part of a computer (like that shown here).  By the late 1950s, a typical installation might have a single large frame holding the central processing unit, to which bundles of wires from peripherals ran.  To those familiar with the similar usage in telephone technology, mainframe would have been a natural usage for this CPU frame.  For example, in this 1961 article, a Western Electric (of AT&T) staff member writes:

Likewise, the output of a computer mainframe is digital...

The term became more widely adopted, in particular for the large central computer used by a company as distinguished from smaller computers which began to appear in the 1960s.  It is not terribly surprising that the earliest source quoted by the Oxford English Dictionary for mainframe is a 1964 glossary from Honeywell, then a producer (among other things) of smaller computers and soon minicomputers.
Comment: So "mainframe" may have been common preexisting engineering terminology for a big rack of central telephone exchange equipment, reapplied to the new big digital equipment filling the same type of floor space?
Comment: hotpaw2: Essentialy, yes. A large rack of wiring and components in both cases.  The technologies were related too; some of the earliest computers used relays (like telephone exchanges) rather than vacuum tubes or transistors.
Answer: Actually, IBM did use the term right from the beginning. Gene Amdahl (one of the lead designers of the System/360 mainframe) used the term in 1964 in an IBM journal describing the S/360 architecture.

see G.M. Amdahl, G.A. Blaauw, and F.P. Brooks, Jr., "Architecture of the IBM System/360," IBM JOURNAL OF RESEARCH AND DEVELOPMENT, 8, no. 2 (1964)
Answer: Etymonline gives this:

"central processor of a computer
  system," 1964, from main (adj.) +
  frame.

In the days when large installations were becoming more common, a computer system would require a specially built room (as far as I know, they still do). Tape drives, disk drives, printers, card readers and the like would be distributed about the space. The "mainframe" refers in such cases to the processing unit and physical memory - which in the case of an IBM 360-158 was about the size of a commercial refrigerator.
Comment: @hotpaw2 Yes, for instance, the IBM 360/50 had a Storage Frame, Power Frame, and CPU Frame. The frame was the standardized refrigerator-sized box that IBM used to hold components. See http://bitsavers.org/pdf/ibm/360/fe/2050/SY22-2832-4_360-50Maint.pdf  The interesting issue is the transition of "mainframe" from describing a part of the computer to describing a type of computer.
Comment: According to Wikipedia, "The term originally referred to the large cabinets that housed the central processing unit and main memory of early computers." So it was really more about the cabinet and supporting "frame" to which the memory and CPU were bolted.
Comment: Which early computer?
Comment: Yes Robusto. The CPU and memory were housed in a large frame, "about the size of a commercial refrigerator." But when operators referred to "the mainframe," we were not talking about the housing of the unit per se.
Comment: Was (adj.)+frame ever used as a term for stuff other than the main CPU and memory mounted in frames or racks?  Also, some early minicomputers were also mounted in frames or racks, but not called mainframes.
Answer: Frame in the mechanical sense of board - although in the early machines it would be a framework of wired connections rather a than a printed circuit board.
The main frame was the central piece containing the processing unit, with other auxiliary frames containing memory, I/O, peripherals etc.
The first mainframe in modern terms was probably the IBM360 in the mid 1960's but IBM never used the term - in fact IBM pretty much avoided the term computer at the time.

Origin of the word "mainframe"?


Duplo Activity table to Lego System Table

Question: We purchased a table with Duplo baseplates on top (activity table) for my son when he was 1 year old. He's now turning six and we would like to convert the Duplo top to the regular LEGO System top. is there a baseplate that has Duplo studs on the bottom (so it sticks and essentially covers the Duplo spaces) and regular LEGO System studs on the top (so that the table can be used with the regular LEGO System pieces. It seems like a shame to chuck the table.
Comment: Don't forget to accept the answer if it works for you!
Answer: To answer your question, no there is no such plate with DUPLO tubes on the bottom and LEGO studs on top. HOWEVER regular LEGO and DUPLO are completely compatible - as long as the regular LEGO bricks are at least 2x2 studs. Just cover the DUPLO table with regular LEGO bricks and you are done...(c;
You could actually use regular LEGO plates too, however the connection won't be as secure as with regular LEGO bricks as plates are much thinner so won't go all the way down to cover the LEGO studs. But they do fit, and their benefit is that they cover a much larger area so you would need less.
Here is an article and some visual examples of how LEGO and DUPLO fits together very nicely: http://thebrickblogger.com/2010/12/lego-duplo/
Comment: you are awesome!!!! I'm going to try that now...now just have to scrounge enough flat duplo plates 2x4 to fill the top :) thanks! The reason for this is that that top has solid rounds and not the originall duplo round to connect to the system so your idea worked when I placed the flat duplo on top first and then use the regular system bricks :) so I am figuring if I get a could of duplo base plates and put them on top first, the table would be good to go I think :)
Comment: Marisabel, that sounds like a plan! You can get some quite large DUPLO plates on BrickLink so you don't have to work with a lot of smaller ones (4x8, 6x12, 8x8 and 8x16). It is just something to consider investing in in the future. You can find them here:  http://www.bricklink.com/catalogList.asp?v=2&pg=1&catString=487&catType=P
Comment: You can use the large bricks such as the [12x24](http://www.bricklink.com/catalogItem.asp?P=30072) to build the surface of the table. This will give it better stability and should bind correctly to the underlying duplo, plus it saves time in assembly.
Comment: Some additional notes: Marisabel is right that the duplo table has solid studs (not compatible with normal legos) when every other duplo brick has hollow studs, so you need a layer of duplo and then a layer of standard. I just ordered bricks to convert a duplo table to standard legos, it needed 12 standard 8x16 plates (tall enough to fit the duplo studs) and 12 duplo 4x8 plates.
Answer: Unfortunatly this is problematic.
Duplo baseplates generally have flat-topped studs, these studs are incompatible with lego. Furthermore thin lego plates don't have enough depth to take up a duplo stud.
So you are looking at at least two layers for the conversion each at least one full leog brick thic. The lower layer would be duplo plates (one lego brick high) followed by a layer of regular lego bricks. You can get oversized lego bricks which would probablly help in making it less likely for your conversion layers to come apart.


Samsung apps cannot be run. Please try again later

Question: I'm using Kies to connect my 'Samsung Galaxy Ace' in my PC. All the options like Music,Photos,Videos and Podcasts working fine. But when I click on Samsung Apps under Store option, its showing an error "Samsung apps cannot be run. Please try again later". Could you help me to resolve this problem...?
Answer: Do you have a Samsung Apps icon on your phone? Have you tried using that one?

It's been a little while since I've used Kies, but it is used for all of Samsung's phones, not just the Android ones. The Samsung Apps icon in Kies only used to list Bada compatible apps, not Android ones, you needed to use the Samsung Apps icon on your phone to get the Android ones.
Edit: Just realised that this question has come up before, for the Galaxy S: Why do Samsung Apps not support the Galaxy S? though that question is from a year ago, so things may have changed since then
Answer: Try to re-install the Kies on your PC.And try it once again because i had the same problem and i got it back by this way.


Which distribution do I get?

Question: Let's assume the stock moves according to a classic Black-Scholes model, and makes a proportional jump with an unknown proportion. Say, it is either +1% or -3% of the stock value, and we know for sure that no other outcomes are possible. After that we assume the stock to move with the same volatility. Interest rates are zero. Hence, the total return on the stock $\xi$ until expiry $T$ becomes
$$
  \xi = \eta_1\sigma\sqrt{t_j} + j + \eta_2\sigma\sqrt{T-t_j}
$$
where $t_j$ is the time of the jump, $\eta_i$ are iid standard normal random variables, and $j \in \{0.01, -0.03\}$. If I have market prices for options for the expiry $T$, I can use them to find distribution of $j$. My question is what is the meaning of this distribution, that is - what can I use it for? In particular, is that really what market things are the real probabilities for the jump? My guess is no, as we'll get the risk-neutral probability of the jump, hence its mean would be zero, even though people may be sure it is 99% possible.
Comment: You still need to specify the probability of the jumps, for example, 50% for each possible jump.
Comment: what is $t_d$? it is not clear from your description.
Comment: @Gordon: was a typo
Comment: @Gordon: why do I need to do that? My point is that I have some market prices, hence I can imply distribution from the market prices. I don't know what the distribution would be in advance
Answer: First your equation for returns is false. Forgetting about the jump, it does not reduce to Gbm returns. The variance term from Ito's formula is missing. In the case of a jump, a similar term should appear.
Secondly, the distribution is obviously not "what market things are the real probabilities": you chose to impose specific sizes for the jump, the market did not.
Finally you cannot expect to imply real world probabilities from option prices since the latter do not depend on the drift.
Answer: If believe you intend that $t_j$ is a fixed time known in advance, for example the day of a contentious election.  And you postulate that the two possible jump sizes are known in advance and agreed uniformly by the market.  This is an artificial assumption -- real markets would price in a continuous range of possible jump sizes -- but is convenient mathematically.
Then you are right, the martingale condition requires that the risk-neutral probability of up-jump and down-jump are such that the expected value is zero.
To try to get information from the options market, you should take the jump sizes as initially unknown and calibrate those from the options prices.  You could still try the simplistic assumption of a two point distribution -- a fixed up jump size and a fixed down jump size.  Optimise a fit to options prices over different choices for volatility and for these jump sizes.  Again there is a martingale condition that translates these jump sizes to probability of up-jump and down-jump.  But now you are getting those from the market, not ad hoc assumption.
Again the probabilities are risk-neutral not real world.  Risk neutral prices tend to charge more for insuring against bad outcomes, so expect the risk-neutral price for the down jump to be an overestimate of the real world probability of that event.  How much of an overestimate?  Hard to say...

Which distribution do I get?


Why would a Tor site need my EMail,does this not defeat the Tor anonymity?

Question: I want to volunteer to be a Tor Relay,but all the mumbo-jumbo about using two flash drives or a DVD, I just do not seem to get to work! Do they sell a Tor Relay disc? And what are safe emails to use if I have to sign-up on a Tor site, or is this a FBI sting trick? It seems if you use a email it beats the purpose of Tor! Safe email that prides itself in the American dream of "PRIVACY" ? Anyone who can give me some EMail providers to research or welcomed $$$$
Answer: yes, it defeats your anonymity! Tor site is a site that works by itself, Tor is just a transport. All the anonymity precautions for websites are applied
Answer: You have confused two things. Tor is designed to protect the anonymity of a person who uses the Tor network to connect to a remote site.
The network does not, and cannot, protect the anonymity of a person who runs a relay. Why not? Because when you run a relay, your IP must be publicized to the Tor network so that your relay can be used in the construction of Tor circuits. Once your IP is publicized, someone will easily figure out who it is who is running the relay.
If, for some reason, it is illegal to run a Tor relay in the place where you live, don't do it! Help Tor in some other way, perhaps by donating to someone who can legally run a relay the money that you would have spent on running one yourself.
Comment: So by giving out my Email address on Tor,it is protected by Tor?Cause sites On the dark web ask for Email address,cause I wanna learn blackhat tricks of the trade.
Comment: I would help greatly if you wrote clearly and asked a clear question. To be clear, you can be a user of Tor, or you can run a Tor relay. It is of course possible for a person both to be a user and to run a relay but the actions are separate. If you are a user, your anonymity is protected to the maximum extent that the design of Tor (and your approach to using it) allows. But as I said in the answer above, if you choose to run a relay (which no one is forcing you to do), then it is not possible to do so anonymously. That is simply an unavoidable feature of the design of Tor.


Donors who gave the same amount in X and Y year

Question: Is there a report in the Current version of CiviCRM that can tell us this? https://civicrm.org/extensions/advanced-fundraising-reports seems to have reports that will show if the giving is increased or decreased year to year, but not if it's exactly the same. Thanks!
Answer: I don't think there is such a report. I would probably look at using Summary Fields extension and then adding a new calculated field that does your calculation - and then report on that.
In drupal I would also consider doing this in Views and using eg views_calc to do the calculation for me instead of creating a calculated field
Comment: I will need to compare 16-17, and 17-18 (etc.) going into the future. It seems like a view offers more flexibility. The other reporting requirement is to ask if they gave the same for X and Y year, but then increased or decreased in Z year.
Answer: I am going to try petednz's approach using Views Calc, but I hacked together a quick MySQL query that pulled me most of what I wanted
<code>select year(receive_date) as year,(select display_name from civicrm_contact where civicrm_contribution.contact_id = civicrm_contact.id) as Name, contact_id, SUM(total_amount) as Gifts
from civicrm_contribution
where (receive_date >= '2015-11-01' and receive_date <='2016-11-01') or (receive_date >= '2016-11-02' and receive_date >= '2017-11-01') or (receive_date >= '2017-11-01' and receive_date >= '2018-11-02')
group by contact_id, year, financial_type_id
having financial_type_id in (11, 12, 15, 25, 26)
ORDER BY name
</code>
Perhaps it can help someone else


Adding a 'juice collection' section on a cutting board

Question: I have a core box bit and I would like to add a trench if you will around the cutting board abot 3/4" in. I do not think you can do it with a router table and i know it has to be done with the hand router. How should I do it? The best I could think of was having a frame around it but there bit would be much to far in, and if I did make it bigger then I only risk the cutting board going flying in some direction and hitting the frame. I could just do it and then cut the wood but I do not want to waste the wood like that. What is the best way to do this?
Answer: If you don't already have one, get a 'router guide bushing' that suits your router. (You might have to replace the base plate to find a bushing that fits.) The only sizing requirement is that the interior of the bushing is bigger than your core bit.
You'll want a rectangular chunk of something to sit in the middle of the cutting board. Size it to give you the cutting path you want. (It can be any material -- it just needs smooth edges.) Hot glue or double-sided tape the guide to the cutting board.
Take progressively deeper cuts -- just a little at a time. The only hard part will be turning around the corners cleanly. Hold on tight and it'll go fine. If you nipped a 45 degree off the corners, it'd be a touch easier.
Comment: I think I will be doing a rectangular chunk of wood. I can not believe I did not think of that. Thank you! And I will look for a router guide.
Comment: A couple of tips: My parents had one a _long_ time ago - the groove curved around the corners instead of being square, it was shallower at one end than the other to encourage everything to flow, and the groove died into the handle area so it was easy to pour out. If your board is deep enough, you could route an indentation for a bowl/container to fit under the handle as a dripping catcher to make clean up easier (to be honest, I think they just put the handle over the edge of the sink).


How can I use Netflix on Ubuntu?

Question: Is there a way to stream Netflix content to my Ubuntu machine?
Comment: Have you tried Chorme?
Answer:
Important:
Please note that Ubuntu releases 12.04, 14.04 and newer now support
  native Netflix playback via
  HTML5.
The solution in this answer should only be used in cases where native
  playback is not possible (e.g. unsupported Ubuntu releases, browsers
  other than Google Chrome).
Also note that as of Firefox 49, Netflix playback is natively supported.

As of December 7th, 2012 the following works on 12.04 and 12.10 (at least).
Note: For new instructions --as of October 2013-- on how to install (Windows-)silverlight (ultimately useful to watch Netflix) in Firefox see at the end.
Open a terminal (Ctrl-Alt-T), an type:
sudo apt-add-repository ppa:ehoover/compholio
sudo apt-get update
sudo apt-get install wine-staging
sudo apt-get install netflix-desktop

Are PPAs safe to add to my system and what are some "red flags" to watch out for?

This will install around 254MB of packages, mainly it will install wine-compholio (a custom version of wine that is able to run Silverlight) and dependencies. If wine is not installed already you may need to agree to use Microsoft fonts (in the text mode window use arrow keys or tab to reach the red "ok" button in text mode when it appears). The download/installation takes around 15 minutes.
Then run the newly installed "netflix-desktop" application from the menu (or from the command line).

If something went wrong in the installation (third party links are involved), don't panic: netflix-desktop will detect that something is missing and try to reinstall it, if that also fails, start over.
When you run it for the first time it will initialize wine and probably ask about installing Mono and Gecko wine packages (I accepted and installed them just in case).
The netflix-desktop application opens up, login to your Netflix account.
The window will open in fullscreen, which is very elegant, but if you want to have control over the window press F11 right away to exit fullscreen mode. (It may also ask to install a Firefox extension --specially designed-- that makes fullscreen mode more friendly.)
Use Netflix as you would normally do.

It worked flawlessly in my Ubuntu 12.04 and 12.10 (I have a Core i7).
(As you may have realized at this poin, the netflix-desktop is really Firefox 17 running on wine without menubars. Press F10 to gain control over the Firefox menu and navigation.)

Credits and references: This information was originally taken from http://www.webupd8.org/2012/11/how-to-use-netflix-in-ubuntu-through.html. Although this is a result of a campaign initiated by www.iheartubuntu.com in http://www.iheartubuntu.com/2012/02/netflix-on-linux-contest.html, resulting in this achievement http://www.iheartubuntu.com/2012/11/ppa-for-netflix-desktop-app.html (by Erich Hoover) which also contains a link for donations to support the development. There is also  https://launchpad.net/netflix-desktop
Bonus: By running this you have a fully functional Firefox 17 (Windows version) with working Silverlight that can be used to navigate other sites, by pressing F10 -> View -> Toolbars -> Navigation menu on the main window you can access any site and be able to use Silverlight.

Alternative Method: Install Windows-Silverlight in Linux-Firefox
Alternatively, it is now possible to install Silverlight inside (Linux) Firefox as if it were a native plugin.  (you can see http://fds-team.de/cms/pipelight-installation.html for more info)
sudo add-apt-repository ppa:pipelight/stable
sudo apt-get update
sudo apt-add-repository ppa:ehoover/compholio
sudo apt-get update
sudo apt-get install wine-staging
sudo apt-get install pipelight-multi
sudo pipelight-plugin --enable silverlight

Then install the UAControl Firefox add-on (UAControl - neko.tsugumi.org) and convince movies.netflix.com that your browser is a Windows one, for example "Mozilla/5.0 (Windows NT 6.1; rv:23.0) Gecko/20131011 Firefox/23.0".
Then go to www.netflix.com.
Source: Pipelight: Use Silverlight In Your Linux Browser To Watch Netflix, Maxdome Videos And More ~ Web Upd8: Ubuntu / Linux blog
Comment: @Lucio, it is `UAControl` (fixed), yes, it is available.
Comment: `E: The repository 'http://ppa.launchpad.net/ehoover/compholio/ubuntu bionic Release' does not have a Release file.`
no long works in Ubuntu 18
Comment: This also works for [hudl.com](http://hudl.com)! Many thanks, @alfC!
Comment: @alfC Is the `AUControl` Firefox add-on still available?
Comment: NO NO NO way, netflix desktop is too resource intensive and the application overlay is extremely annoying.  Add pipelight and use your exsisting firefox install.  See my instructions below.
Comment: The first method is never going to work, neither the second, first of all you need to install wine-staging from the repository ppa:ehoover/compholio
Answer: Native HTML5 playback on Ubuntu 14.04 and up
You will need an updated installation of Google Chrome (not Chromium; and make sure to choose the right package for your machine):

Head over to Netflix and try out a movie or show. Everything should be working fine now.
If you are facing playback problems try lowering the quality to match the capability of your hardware. I would recommend a computer better than a 1GHZ 1GB Netbook.¹

1: (as I experienced stuttering on that level of device; Nevermind, current update has relieved most all playback issues with my netbook.)

Bonus: Netflix Webapp
You can integrate Netflix with your Ubuntu desktop by creating a nice .desktop launcher:

Download an icon for Netflix to use. Personally, I usually search google for a suitable icon
This one by Dakirby309 looks good:

Save the icon as netflix.png in your home folder
Create a file called Netflix.desktop in your home folder
Open it in a text editing program like gedit
Insert the following text:
[Desktop Entry]
Type=Application
Name=Netflix
Exec=google-chrome -app=http://www.netflix.com
Icon=/home/USERNAME/Pictures/netflix.png
Terminal=false
StartupWMClass=www.netflix.com

Make sure to replace /home/USERNAME/Pictures/netflix.png with the correct path to your Netflix icon.
Save the desktop file and exit your editor.
Make the file executable by right clicking on Netflix.desktop and heading to Properties → Permissions tab → Execute: → Check the box Allow executing file as program
Drag the icon to your launcher (don't remove/move the original)

Now you have a Netflix WebApp!:

Alternatively you can also use the Chrome plug-in and launch it in "Windowed" mode by doing the following:

Right clicking on the app
Select Create shortcuts:

Only check Applications menu and confirm your choice

This will make Netlix available in the Dash:

If you don't like the appearance of the scroll bars, you can enable Chrome's overlay scrollbars. Go to chrome://flags/#overlay-scrollbars and Enable them. Now you have scrollbars that complete the experience:
Comment: In your screenshot, you seem to be watching a Netflix show on *Chromium*, how?
Comment: ;) chromium now links to the chrome widevine, you need to copy over the widevine plugin files, or install chrome in tandem, as well you need to spoof the user agent.
Comment: the path for Chrome plugin has changed. I used this new [link](https://chrome.google.com/webstore/detail/frameless-for-netflix/djkbcbljoippiechcnmbeohnijifgdfk/related) to launch directly in "Windowed" mode
Comment: Does not support 5.1 surround audio  :(
Answer: For firefox, after version 49 you can also watch netflix on linux without any extra steps, firefox will download the native google widevine CDM plugin and play protected content:
Now that I have Firefox 49 or higher, how do I watch Netflix?
So this are the needed  steps:

have a netflix account! :)
install firefox 49 or above
recommended: install a user-agent switcher add-on. i use http://mybrowseraddon.com/useragent-switcher.html, but almost all user-agent add-ons should work. you can also edit directly the firefox user-agent, but not recommended, as this will send the chrome user-agent to all sites and that might break other things. That add-on can be configured to send only chrome user-agent to netflix site.
select in the user-agent chrome+linux and press edit and change the chrome version to 53 or above, like this:
Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.34 Safari/537.36
Old chrome versions will block netflix from working, so this is important. You may need to update the user-agent to the latest version (by checking a local install or trying something from http://www.browser-info.net/useragents)
Also in the text box, replace the "all_urls" to netflix.com. This will apply the changed user-agent to netflix only
Enter netflix, trying to see a show/movie, firefox will warn that it needs to enable DRM support. Accept and it will download and install the widevine DRM plugin. Wait a minute and reload the page. Sometimes you need to go back and try again, but it will work

I will ask netflix about the status for supporting firefox on linux user-agent and update this when needed
Comment: Steps 3–5 are obsolete for 16.10. Netflix on Firefox works out of the box.
Comment: @Wrzlprmft correct, netflix finally works out of the box with linux firefox (and now several other linux browsers too, as long they have the DRM support)
Comment: Does not work with Surround audio :(
Comment: @Jonathan Currently, as per https://help.netflix.com/en/node/14163, netflix report that you do not have 5.1 in HTML5 video and silverlight, so basically no 5.1 in any browser and OS. Not a firefox nor linux limitation
Answer: Chromium does not support Netflix because of the lack of a needed component. You can manually install this component, but it's a hassle and not really worth it.
Firefox doesn't support Netflix either, at least as of 2014.
If you want Netflix on Ubuntu, you need to use Google Chrome. Download the DEB file from Google's website.
More details:
http://www.pcworld.com/article/2687243/netflix-on-linux-how-to-get-it-today-and-why-its-such-a-pain.html
Answer: PlayOn — the service which drives Netflix (and Hulu) — will be rolling out an HTML5 client which should negate the need for Silverlight (and Moonlight). It's out for the iPhone now, and I assume that it will shortly be used to stream PlayOn services to Linux Machines.
Comment: The fact that PlayOn is in the process of switching to HTML5 properly wont change anything as regards to playing their stream.

They will still use a proprietary and DRM protected video format, and they will most certainly not make a plugin for Linux.
Comment: Just a note, from two years later, still no HTML5 client (fully). Still no Linux port. Still no luck watching Netflix on Ubuntu.
Comment: Thanks Marco. I already have PlayOn so will be keeping an eye on it.
Comment: worthless still would need to run a windows box.
Comment: @rlemon While a Netflix solution now exist, [PlayOn Media Server](http://askubuntu.com/questions/240786/is-there-a-work-around-to-get-playon-media-server-to-work-on-ubuntu) is still without a solution
Answer: I read a while ago that it might be possible to run a Wii emulator instead of virtual box, but I don't think that would be an improvement for most people. I've been meaning to try Netflix in an android emulator since the app came out, however I still need to test if it will actually work. The problem is that the app is only "approved" for certain phones. There is a hack that is suppose to work for rooted phones, So I think there's a good chance this could be a better solution than virtual box, but it's hard to say for sure.
If someone else gets this working please let me know.
Answer: Moonlight, while it is an open-source alternative to Silverlight, does not work for Netflix. The reason that this does not work for Netflix is that Netflix also requires DRM support, which Moonlight does not give.
There IS a way to watch things on Netflix through Ubuntu though.
You will want to virtualize Windows XP/Vista/7 on Ubuntu. I would recommend Virtualbox, but you are free to use whatever you want. Under the virtual machine, you can use the real Silverlight and DRM-support and watch Netflix.
Answer: Pipelight
Pipelight is a plugin that builds upon Erich Hoover's Netflix-Desktop to allow Ubuntu users to watch Netflix from within a native Firefox browser.
Web Upd8 article
Add compholio and pipelight ppa
sudo apt-add-repository ppa:ehoover/compholio
sudo apt-add-repository ppa:mqcheal/pipelight
sudo apt-get update
Install Pipelight
Close your browser first!
sudo apt-get install pipelight
Now Silverlight will work on some sites but Netflix and some others check the browser user agent and will not play on a Linux machine.
Install a plugin to change user agent
I used User Agent Overrider
In Firefox got to Tools -> Add Ons and search for User Agent.
Install User Agent Overrider
Select the latest Firefox/Windows combination.
Head over to netflix.com and enjoy.
This is from an article on web upd8
Comment: `Pipelight` is what worked for me. For the user agent, I used (as in another answer above): `Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.34 Safari/537.36`
Answer: Netflix desktop is too resource intensive and the overlay is VERY ANNOYING, I would HIGHLY recommend the following steps and use Firefox.
Add Netflix for Firefox

Open Terminal
sudo add-apt-repository ppa:pipelight/stable
sudo apt-get update
sudo apt-get install --install-recommends pipelight-multi
sudo pipelight-plugin --update
sudo pipelight-plugin --enable silverlight

add user agent overrider to Firefox Add ons
change user agent string to windows/chrome34

Now you won't have a dedicated application for Netflix and you can use your existing browser installation.
Another non related benefit of pipelight is that you can enable the latest Flash version with it.  No need for pepper anymore! :)
Comment: `Pipelight` is what worked for me. For the user agent, I used (as in another answer above): `Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.34 Safari/537.36`
Answer: Ubuntu 20.04 (snap Chromium)
(This information can also be found in the original article: https://que-cosas.blogspot.com/2020/04/ver-netflix-en-el-chromium-de-ubuntu.html)
1º We download Chrome to use its Widevine.
We can do it by means of the following command, which will provide us with the .DEB file where we will find the desired Widevine folder.
wget https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb

Then we will decompress it in a folder that we will name tmp.
dpkg -x google-chrome-stable_current_amd64.deb tmp

2º We changed the permissions of the Chromium snap pack.
As it's installed, there is a read/write permission on disks that does not allow us to make changes and therefore does not allow us to install Widevine. We can change it from Ubuntu Software (the snap shop).

3º Copy or move the WidevineCdm folder inside Chromium.
The next step is to move the plugin to the place that Chromium needs to make it work. We can do it as follows:
mv
tmp/opt/google/chrome/
WidevineCdm $HOME/snap/chromium/current/.local/lib/

Once this is done, we can delete the temporary file and the Chrome installation file.
rm -R tmp
rm google-chrome-stable_current_amd64.deb

4º We have to trick Netflix into believing that our Chromium is a Chrome.
This step is based on a browser property called User Agent. We are interested in knowing our User Agent, for this we can use the following link:
https://www.whatismybrowser.com/detect/what-is-my-user-agent
Right now I'm getting the one on my Chromium browser next:

Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) snap Chromium/81.0.4044.122 Chrome/81.0.4044.122 Safari/537.36

And that's not going to help us watch Netflix, we have to modify the part where it says snap Chromium so that it only says Chrome. So that it looks like this:

Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.122 Chrome/81.0.4044.122 Safari/537.36

We'll get that by putting an extension on Chromium that will allow us to make this change. For example with the User-Agent Switcher for Chrome extension from the Google Store:
https://chrome.google.com/webstore/detail/user-agent-switcher-for-c/djflhoibgkdhkhhcedjiklpkjnoahfmg
And with all these steps, and once the extension is configured with the Chrome User Agent you will have no problem seeing Netflix in Chrome on Ubuntu 20.04 and without installing Chrome.
Answer: Try running these commands:
sudo apt-add-repository ppa:ehoover/compholio
sudo apt-get update && sudo apt-get install netflix-desktop

Then find netflix in the launcher and it should work.
BUT if it doesn't work the first time, like it didn't for me, try this:
rm -Rf ~/.netflix-desktop
sudo apt-get install netflix-desktop

I got my answers from here: http://www.iheartubuntu.com/2012/11/ppa-for-netflix-desktop-app.html
It has some further troubleshooting notes that I didn't post here so check it out if this doesn't work for you.
Comment: No longer works in Ubuntu 18
Answer: I had a similar problem, but I managed to solve it as follows;

I downloaded the .deb package from google, but it seems the new Gnome-based software center did not install it properly.
So, instead, I used sudo dpkg -i <*package*>.

Worked for me.
P.S.: I was confused for a while with Chromium vs Chrome. They are different projects, and only Chrome works with Netflix, not Chromium.

How can I use Netflix on Ubuntu?


What are the differences between "clincher" and "tubular" tires?

Question: What are the differences between "clincher" and "tubular" tires?  I'm just a casual road cyclist at this point and don't put any more than 200 miles in over the course of the week.  I'm looking to upgrade to some better, lighter wheels, but want to make sure I go with the correct type.  I'm looking for something that will be easy to fix on the road and doesn't add a lot of complication when problems spring up.
Comment: I'll comment that I've been doing "adult" cycling for over 40 years, about 25 of those years pretty serious, been in about 2 dozen mass rides of one sort or another (from 50 milers to week-long tours) and I have never, that I was aware of, encountered a cyclist with tubular tires.  No doubt in some of the group rides there were a few tubulars, but they would have been in the cluster of elite cyclists that were always gone before I got there.
Answer: If you want simple and easy to fix then you sure as heck don't want tubulars.
Someone else will probably provide more details and links, but clinchers are rims/wheels with a tube, then a tire is mounted over the tube and the bead of the tire is hooked under a lip on the rim.
Tubular rims have no lip.  The tire encases the tube completely and is sewn in typically.  SO fixing a flat means cutting open the tire and patching the tube, then sewing it back up.
The tire assembly is glued to the rim.
Heat from brakes can melt the glue supposedly and cause tires to roll off.
The rolling resistance used to be much better on tubulars.  Unless you are a purist or a pro I don't think there is a reason to go with tubulars these days.
Comment: Heat from the brakes shouldn't melt the glue unless you've used something other than tubular glue, glued the tire on incorrectly, or are riding your rim brakes doing downhill mountain biking, in which case you're certifiably insane (rim brakes and tubulars on a MTB?).
Comment: Tubular tires won't come off the rim unless they've been improperly glued. You can realistically ride several miles on flat tubulars if you have to. Do that with clinchers, and you'll be riding on your rim pretty quick.
Comment: So are you saying that tubes did not roll off?
Comment: @Stephen Re-reading your last comment reminds of the time my brother flatted his rear (using singles) in a race 1km from the finish. He still managed a place.
Answer: Clinchers
Pros

cheaper
more common
wheels are more common
easier to patch on the road, no need for gluing, stretching tire, etc

Cons

if you flat, you can't really ride on it
some say a lower quality ride
will always be heavier (tube, tire, clincher interface)

Tubulars
Pros

the lightest practical tubulars will always be lighter than the lightest clincher
if you flat, you can ride on it for a little longer
if glued properly and the tire will stay on the rim even if it flats
ride quality

Cons

costs more (rims, tubulars)
more difficult to maintain / repatch as an individual
you could get tire/rim seperation
Answer: Clinchers tires and rims are more convenient in that they can be repaired easily on the road, are cheaper, and have more options available. However, they are heavier, won't stay on your rim at high speeds if you get a flat, and have a higher rolling resistance.
Tubular tires and rims are more expensive and require a lengthy gluing procedure to replace the tire when it flats. However, they have lower rolling resistance, weigh less, and are potentially safer when going flat at higher speeds (if they have been glued properly).
In my opinion, the practicality of clinchers outweighs the benefit of tubulars in all road-racing scenarios short of pro-level racing. One approach to mitigating the downsides of tubulars, however, is to have a set of tubular "race wheels" that you use only on race day, and a set of clincher "training wheels" that you can repair on the fly if you go flat 40 miles from home.
The one place I think tubular tires still reign, even for amateurs, is at the velodrome. You're never far from a ride back home if you puncture a tire. The opportunity for having a flat is greatly reduced because of the far fewer miles you put on the wheels plus the lack of road debris on the track. And it's far safer to have tubulars in case of a flat, where you can still ride on rubber down to the apron. With a clincher, if you lose the tire, it's easy to fall if you wind up riding on your rim on a 37° banked curve.
Comment: Back when I started riding seriously in the mid-70s, I read about the then-still-fairly-common tubular tires.  Glue..Sewing...
Not for me...  Never regretted avoiding the things, which are now at best...Rare. Maybe pro road racers still use 'em, but they don't have to fix 'em.  (hand the wheel to the tech and take a nice fresh one in return...)
Comment: I just bought a pair of tubulars for the track, and they come sewn up nowadays. Still a PITA when you get a puncture, but I should get a few racing seasons out of those tires.
Answer: Anyone who has changed tubular tires often will attest that it is not difficult, and the process can actually be much faster than changing a clincher, depending on the clincher and the rim in question.  Proper glue application (not too much, but still enough) and using the right glue, are very important steps.  Unless the glue is very old, the remaining glue, after the flat tire has been stripped, will hold a new tire on for most triathlon riding as long as you avoid sharp cornering and strong leans.
I have actually toured through Europe on a pannier equipped race bike, using sew-ups, and had great success and a wonderful ride.  You just cannot beat the ride that tubulars give you.
As far as repairing the sew-ups go, of course this is done at a later time and hopefully you'll find someone at a shop who does it on a regular basis, to do it for you.  But it is really not that difficult to do.  However, repairing your flat tubular in the field is out of the question.  The idea is to carry a spare tubular tire, or two, and swap it out in the field, and fix the flat later.
Another advantage of tubulars is that you will be changing-out the entire tire, and not just the inner tube.  If your flat was caused by something that also damaged the tire itself, and not just the inner tube, then changing out a clincher's inner tube will do little good.  This logic also applies to small pieces of glass or steel that may remain in the tire, difficult to detect, after you have replaced the inner tube.  After changing a clincher inner tube, once you are back on the road, you may experience a second flat due to the small piece of glass in the tire that you did not catch because you were in a hurry.
Comment: I've used sewups on my road bikes since the 80's.  Although it's more difficult to patch a sewup than a clincher, it's easier/faster to change a sewup on a ride than a clincher.  I've ridden two or three miles on a flat sewup without damaging the rim.
Comment: I've done field repairs of a flat tubular. It's a pain and not ideal but not impossible, as you seem to indicate.
Comment: how do you swap out a fresh tubular tire for a flat one if the tire and tube have to be glued or taped or whatever to the wheel?
Answer: a. Clincher and Tubular  refer to the type of rim on the wheel, and what type of tire can be used on the wheel.
b. Clincher wheels are the most common type and are used with a tire and an inner tube. If you get a flat tire with a clincher, you can change out the inner tube and continue riding fairly quickly.
c. Tubular wheels are lighter and cheaper, but you must use specific tubular tires. These tires combine the tire and inner tube into one piece, and must be glued onto the wheel. Generally tubular tires are more expensive than clincher tires and they are more difficult to change, in the event of a flat. To change a tubular tire, you will need to remove the glued on tire and reapply fresh glue and a new tubular tire, then allow some time for the glue to cure.
Comment: I haven't found singles harder to change. If anything, they are easier; see the answer by Arn.
Answer: If you get tubular tyres with removable valves you can put some sealant inside them which will often cure punctures for you often without you even noticing.
I tend to find that I change tires on the second puncture but I have read of people finding eight sealed holes after a ride on a (MTB) tubular tyre. With a clincher this would probably have meant stopping to change or repair the inner tube eight times.
Tufo and Stans sealant words well but is not all that cheap. For economy and even efficiency, "home brew sealant" (Google) can be used containing liquid latex, such as sold for making masks or as a sewing glue, a drop of ammonia water and water if thinning is needed, with some added fibres such as cornflower, pepper, glitter or artificial grass used in model train terrains.
Sealant can apparently be used in clinchers too but sealing a thin tube, rather than a tyre with threads, can be less effective and or less permanent I presume. I repair my clincher punctures but seal tubular punctures.
The 30 grams to 50 grams of sealant if added prior to puncture will reduce or remove the weight advantage of tubulars, but combined with the fact that tubulars can be ridden with very low (or even zero) air pressure, means that punctures often will not stop you in a race, or on your commute. The puncture will usually seal and you can just keep riding on a softer tyre.
Tubulars can be pumped up higher, eg to 175psi for use on smooth surfaces such as velodromes. The roads around me are good so, mainly for puncture resistance, I have ridden on tubulars at about 145psi, a pressure not allowed by the clinchers that I buy.
I doubt that others will do the same but, I find that 100 yen store (dollar store) leather glue works for me, providing an adequate tyre to rim bond but I am not a racer. I get my latex at that price too.
The biggest drawback of tubulars is that one should really carry a spare tyre and not just a spare inner tube for when the puncture is too big for the latex to seal. That said, I feel pretty confident that my latex will hold out or seal enough to allow me to get home.
Due to the ease of carrying a spare inner tube and repair kit, given the choice I think I would probably use clinchers since I am not a racer. But I bought some cheaper-than-clincher, deep-rimmed carbon tubular wheels and I enjoy using them often. If I were racing, I would save my tubulars for race day and use them in preference to clinchers for their slightly superior ride quality and self-sealing properties mentioned above.
Addendum
Apparently some people put sealant in the type with non-removable valve cores (though perhaps not containing fibre) and that it is also possible to inject sealing adhesive directly into puncture holes, I believe.


Information about an expanding event horizon

Question: Assume an observer sent a beam of photons close to an event horizon, say at some distance x (a distance far enough to avoid the photons falling in.) This light would still be observable, albeit red shifted and with it's path curved appropriately. Now assume the black hole absorbs enough mass to expand it's event horizon beyond the distance x. This stream of photons would stop. Does the observer not have information about a process that occurred exactly at the event horizon, that is it's expansion? Isn't this a region that one should not be able to get any information about due to the fact that nothing could contact the event horizon and return to the observer?
Comment: I am a little unclear about this question's formulation. Is the Observer actually at x and sending photons from there? I would expect there to be some object at x (somehow maintained there) which was sending photons. Are the photons heading in all directions from x? Then is the Observer at infinity, somewhere nearby to x, at the Event Horizon or moving into the Black hole?
Comment: The observer would be somewhere nearby by x, not infalling- to observe a beam through a point that is at distance x- with a photodetecter detecting the light after it has passed through that point. The beam would originate near x from a source not infalling as well. The image I'm trying to convey is one of "shining a light" close to a black hole, almost across the event horizon, but not close enough to be absorbed.
Answer: When you look at a black hole, you never see the actual event horizon, because the proper distance to it is infinite and it would take a light signal an infinitely long time to come from it. What you actually see is the matter falling in as the event horizon is about to form. That's why an older name for black hole is "frozen star".
So, if you can't even observe the event horizon form, you definitely can't observe it expand. In your experiment, the closer the photons get to the event horizon the greater the proper length of their path, so the longer you have to wait to see them.
Also, you really should think of the event horizon as a 3-dimensional surface in spacetime, not just a 2-dimensional surface in space. The closer the worldline of the light gets to it, the longer you have to wait, so you can't get any information from the 3-surface itself.
Comment: So with no experiment able to actually discern if a black hole exists- why do we keep talking about them like they are real? Isn't this a clear violation of the scientific method? Should we not instead be looking at "frozen stars"- an object where no event horizon or singularity has formed yet?
Comment: And (ran out of time time to edit my comment) if the answer to this is that an infalling observer see's the black hole form in finite proper time- what good is this as every other observer in the universe has no access to that information?
Comment: Exactly. There's this catch-22 situation because the only way to observe things at or inside the event horizon is to fall inside, but that takes an infinite amount of time from the perspective of any external observer, so you can't tell any of your friends. But that doesn't mean that all GR predictions about black holes are unfalsifiable.
Comment: For example, when Advanced LIGO is running, we'll be able to observe gravitational waves from inspiraling black holes, and although these are technically just from the extremely curved spacetime around the event horizon rather than the horizon itself, the pattern of the waves will look different from other things like inspiraling neutron stars, and we can compare it to detailed quantitative predictions made by numerical GR simulations. If it looks like a black hole and does everything we expect a black hole to do, why not call it a black hole?
Comment: And we would be able to distinguish this data from that of say a neutron star on the very cusp of being black hole, where the time it takes to reach the surface, as seen by an outside observer, is longer than the age of the universe? Wouldn't every process, even the absorption and reemission of light and all other physical processes, take too much time to practically measure? (Thank you ahead of time for your patience- I just feel like there is some sort of discontinuity here that I'm having trouble understanding)
Answer: As I now understand the formulation of this question we have the following situation:(1) an observer is situated near the Event Horizon of a Black Hole;(2) a light source is situated a similar radial distance from the BH and is shining light which is reaching the Observer;(3) the radial distance of both from the BH is approximately x; (4) the Event Horizon expands (reducing the distance between it and the Observer/light source).
Several observations about what is likely to happen here:
(1) The Event Horizon is at R=2M for a Schwarzchild solution, but there are unusual photonic effects nearby outside too. At R=3M the photons will go into orbit around the BH. So perhaps if nearby the Observer is picking up a photon from its orbit. Even if a little further out the light bending will be quite extreme, and so the Observer is likely to "see" the light coming from another region of the sky.
(2) The photons of light from the source may already be in a kind of elliptical orbit which drags them into R=2M.
(3) With an expanded Event Horizon we are assuming greater gravitational force on both Observer and Source. At some point one or both may be overwhelmed by the increasing gravitation near the Event Horizon. Thus they would be unable to maintain any fixed distance, and be drawn in simply because they dont have an infinite power source in their engines. If such movement occured the light from source to Observer could be distorted further as they try to maintain position, but move in different orbits.
(4) As the Event Horizon approached both would cross the R=3M region, at this point the light source might no longer reach the Observer, depending on exact distances.
It should be noted that the "potential curve" for gravitation near a Black Hole is unlike a standard Newtonian one near a massive object. The exact trajectories of objects is also heavily dependent on a quantity related to the angular momentum of the photon.
To complicate matters further the use of the term "Event Horizon" in this expanding example may not be appropriate: other terms like "apparent horizon" may be more appropriate. In a sense the Event Horizon is theoretical construction best applicable to a Black Hole at the end of (its) time.
In short I am expecting the stream of photons to stop reaching the Observer somewhat before the Horizon meets the Source, unless the Source and Observer are on some very specially constructed orbits, in which neither are at position x. The rays connecting the two might reform later as both head into the Black Hole, resulting in a light that is intermittent. Finally I believe that anything demonstrated here, is a demonstration of the properties of an apparent horizon.
Answer: Let the light source be pointed directly upward. Assume that the observer (who receives the light) can remain hovering above the black hole as it expands. The observer would notice that the redshift of the light ever increases, until such moment that the last photon is received (subsequent photons fall into the black hole). The last photon could be received at any point in the observer's future: the closer to the horizon (but still above it) that the photon is emitted, the further in the observer's future it is received.


What is required to be able to sneak attack with a spell or ranged attack?

Question: I'm playing a 3rd level rogue, and I'm looking at at taking a few levels of sorcerer for the Draconic bloodline's claws, and as a prerequisite for the arcane trickster prestige class. Since I'm going to be casting spells as a source of a lot of my damage, I'm curious about what is required to be able to add sneak attack damage to a spell. Since a lot of the sorcerer spells have a long range, I'd also like to know when I can add sneak attack damage to a ranged spell, and how this compares to the rules for sneak attack damage from a ranged weapon.
Answer: Sneak Attacks with spells follow the normal rules for sneak attacks
Specifically, the phrasing of sneak attack only specifies weapons in the section on nonlethal damage (which cannot normally be dealt with spells anyways). Touch attacks, ranged touch attacks and other such attacks caused as part of spells may therefore be used to deliver sneak attacks so long as they fulfill the normal conditions of a sneak attack.
In other words, sneak attacks with spells must meet the following conditions:

The spell requires an attack roll (otherwise, it is not an "attack" for the purposes of sneak attack)
You are flanking the target or it is denied its Dexterity bonus to AC.
Ranged attacks are made within 30 feet
The spell must deal damage

The 3.5 rule limiting volley attacks (such as scorching ray) to 1 sneak attack unless they are made using a full-round action is technically not a part of Pathfinder, though it is a perfectly reasonable ruling on the DM's part.
An Arcane Trickster's Surprise Spells ability is an exception to the above rules—one could, for example, cast a fireball in the surprise round and sneak attack a large number of opponents.
Damage Type: Sneak attack damage is of the same type as the original damage, with the added subtype of precision.
Comment: Should not flat footed also be in your list of conditions? Flat footed is similar to but not identical to denied dex bonus.
Comment: Flat-Footed can cause denied dex bonus, but if an enemy _somehow_ managed to keep their dex bonus while technically remaining Flat-Footed (perhaps through a poorly worded Uncanny Dodge equivalent) they would not be subject to sneak attacks.
Answer: Being a 10th level arcane trickster.
http://paizo.com/pathfinderRPG/prd/prestigeClasses/arcaneTrickster.html#_surprise-spells

Surprise Spells: At 10th level, an arcane trickster can add her sneak
  attack damage to any spell that deals damage, if the targets are
  flat-footed.

This isn't a true sneak attack, so it's apparently not subject to the 30ft range limit, nor does it apply to all the other instances you can normally sneak attack.
The subtext I get from the combat section is that spells are not "attacks" and therefore do not benefit from sneak attack, except in special cases such as the arcane trickster.
Comment: Aren't spells that call for attack rolls considered attacks?
Answer: I want to add that you should check out the write-up here about Sorcerer bloodlines for the Arcane Trickster: https://rpg.stackexchange.com/a/41406/2458
For many Arcane Tricksters, Scorching Ray is really their bread and butter spell. When you take 4 levels of Sorcerer your BAB falls behind heavily. So it's hard for you to be on the front lines. Using Ray spells, you get to attack Touch AC, which makes you dramatically better at this.
In the post above I list several bloodlines that actually get a Ranged Touch Attack as a spell-like ability which helps support the strategy of sneaking around and firing spells with Sneak Attack damage. However the Draconic Bloodline ability could also really help with your damage on Scorching Ray.

If you're really dedicated to being full melee combat and sneak
attacking, take a look at Shocking Grasp as a key spell.
If you really just want the claws, take a look at a magic item like Claws of the Ice Bear which give you claws and some useful Rogue bonuses.