Is there an equivalent of "The A.T. Guide" for the Pacific Crest Trail?

Question: I'm asking on behalf of my roommates who want to hike the Pacific Crest Trail. We all recently moved to San Diego from the East Coast, and they're trying to find a book as informative and detailed as The A.T. Guide, but having trouble, online as well as perusing through several bookstores here in San Diego. Would anyone have any suggestions? Thank you.
Answer: There are several equivalents just as there is for the AT. I would consider  Halfmile maps combined with PocketPCT.

Halfmile's PCT maps
'Erik the Black' books
PCT Data Book
Pocket PCT (No longer available at this link as of March 2018)
U.S. Forest Service PCT
Yogi's (No longer available as of March of 2018)
Wilderness Press books / databook ('official')

The PCTA also provides a listing, which is no longer at that page, as of March, 2018, and sells books. Guthook had a review on his blog, which is no longer available as of March 2018.
I would also add that while maps are not as popular on the AT they are most common on the PCT. Postholer have the nicest maps but Halfmile maps sometimes include useful comments which are a plus.
As for which one's you should bring with you, this is an entirely different question.
P.S. Feel free to edit/add more guidebooks
Comment: Hi ppl! Your links to Yogi's and Guthook are dead, as is the list from the PCTA that you mentioned. I've noted the dead links in the question rather than deleting them, just to let people know that these things were there but aren't any more. You might want to look at all the PCTlinks. Some just go to the front page of the Pacific Coast Trail Association shopping page. Your other post that you linked to also has some dead links, so I'll note those over there.
Answer: As of 2017, the majority of PCT thru-hikers are relying on apps. The most popular option is known as "Guthook," from Atlas Guides. Other popular options include "Halfmile" and "Hikerbot."
These apps are comparable to AWOL's AT guidebook in many ways. While offerings vary between apps, you can expect to find a GPS route of the trail, elevation profiles, locations of campsites, and detailed listings of resupply town resources.


When should I hydrate my dry yeast?

Question: I'm brewing beer tonight (in roughly three hours) and I've decided to try rehydrating my dry yeast instead of throwing it directly into the cooled wort. If I boil a couple cups of water, how long does it usually take to get down to 90 degrees so I can pitch the yeast into it? How long can I keep the yeast in the water? How/when do you guys rehydrate your dry yeast?
Answer: It really depends upon the type of container you're using, how much water, geometry, material etc. In a glass jar, the water could stay warm for a couple of hours. In a stainless steel jug (I use) it takes about 30 minutes.
What you can do is instead is boil some water now and put that in a covered sanitary container. The water should cool to below 90F before you're done brewing in 3 hours. At pitching time, use a thermometer to check the temperature of the water, and add more boiled water to bring it back up to 90F.
Rehydrating yeast is beneficial to your yeast. You can lose up to 40% of the cells by not rehydrating.

When should I hydrate my dry yeast?


What was Ruby used for before Rails?

Question: What type of programming or project would only involve the Ruby language? Rather than using RoR. What was Ruby used for before the Rails framework existed is what I am basically asking.
Answer: There is nothing that other programing languages can do that Ruby cannot also do. It is, like most other programming languages, a general-purpose language.
Any language that supports calling C API functions can do anything C can do. And, since most operating systems are written in C and ship with C libraries for everything the OS supports, then therefore Ruby can do any of those things. That includes creating and manipulating windows and widgets, connecting to Internet hosts, or anything else.
In theory, one could use Ruby to write an operating system (though it's certainly not well-suited to the task), given the low-level primitive objects that are needed. One could also embed Ruby in any application or service that has C bindings, no matter what language it was written in. You could also write a compiler in Ruby. (I know several people who have done just that.)
Comment: And, of course you could write a Ruby interpreter in Ruby (without `eval` of course, that's not fun). +1
Comment: @WTP: I believe that's part of the goal of Rubinius - everything except the VM core is written in Ruby.
Comment: So what was it actually used for?
Comment: @djechlin: Anything. Everything from build systems to web applications. Rails is *merely* a framework. Asking what it was used for before it got one of *several dozen* web frameworks implies it has no use without that framework, which is patently ridiculous. It was used for all of the same things that Python, PHP, Perl, and a dozen other languages were used for.
Answer: I learned Ruby (and then Rails) as a hobby over the last few months. So take this with a grain of salt as it's based on short term hobby learner Ruby knowledge, and not a real-life long term commercial Ruby programmer career or anything...
I get the feeling that pre-Rails Ruby was used mainly as a general purpose language for writing backend scripts and utilities, mostly by the OSS/Linux crowd. The GUI side is a (relatively) weak point, which is why a lot of it was more command line and backend - and you don't see too many popular general usage GUI desktop applications that are written in Ruby.
Essentially, if you wanted a modern, fully OO, and generally nicer language for doing virtually any general purpose thing on Linux (that you might have written in Perl, csh, etc, 10-15 years ago), Ruby was a relatively popular alternative among some of this circle, and a lot of people in that crowd were taking it up.
Answer: Ruby's aim was partly to take the best qualities of Perl, clean them up, mix in true Object Orientation and a few clever functional features. Consequently it's starting point was really aiming to do the same types of things that Perl is used for, particularly back-end scripting, particularly on Linux systems.
I would say that now one of the things that makes it so useful now is that it is a great tool for developing Domain Specific Languages ( one of the things that is used in Rails and associated projects a lot ) and as these grow in popularity there is a good chance that this will be something we will see more of in future.
Answer: Ruby is a multi-purpose programming language and can be used for almost anything.  (obviously just because it can be used for anything doesn't mean it should be)
From Wikipedia (notice the words 'general-purpose')

Ruby is a dynamic, reflective,
  general-purpose object-oriented
  programming language that combines
  syntax inspired by Perl with
  Smalltalk-like features
Comment: Desktop Application? Server Side Application? GUI creation? All those?
Comment: @opensourcechris - I believe so.  Here's a GUI library for developing desktop apps (including Windows) http://rubyforge.org/projects/wxruby/
Comment: -1, doesn't answer what it *was* used for.
Answer: I used Ruby for color calculations for my former employer. I made some small scripts and bit bigger GUI tools to make these calculations.
Ruby was a very easy language for this kind of job. It worked well in Windows and it really was easier to use than the other option, Pascal.
Rails is just so different world compared to simple Ruby scripts, but so is Web. I've used Ruby also with Sinatra which gets you a bit closer to the HTTP layer with requests and responses right in front of you.

What was Ruby used for before Rails?


How do you connect the Blackberry Simulator to BlackBerry Enterprise Server (or Express) for testing?

Question: It seems to be a tricky process. I found some information on the process online but I couldn't find all the information in one place.
Answer: Here is the KB article that most people link to that gives an overview of the process:
Connect_the_BlackBerry_Simulator_to_a_BlackBerry_Enterprise_Server
Here is a video making the process look pretty simple:
Java Development - Connecting the Simulator to an Enterprise Server - BlackBerry
What isn't mentioned anywhere I've found is that you must allow connections via TCP on port 4101 to your BES server. I don't think it's necessary to forward connections from the outside to your server, but it seems to be necessary when using the BB Simulator.
You get a clue that it's trying to connect on port 4101 if you open the BB Device Manager while it's trying to connect. The BB Device Manager is a program running in the system tray. If you watch the video carefully you'll see him open it one point.


Should this question be split?

Question: A discussion began in the comments on Can I get an ebook from the library in the United States? should it be split and the answers that are non-USA be recreated on the splits?
Comment: Just a note that if this is done, the original answers will be deleted and need to be re-entered on the appropriate questions. Likely the original answer poster will want to do it since they are going to lose the reputation once the original answer is deleted. They would also only regain the reputation they lost if they were to receive the same number of upvotes as the original answer. This may or may not be important to some people.
Comment: @JasonDown I believe this can be tagged status completed, only mods can apply the tag.
Answer: I hesitate to delete answers, the site is young and many of our members have little rep at this time.

This question can be clarified to be US centric.
Leave the non-us answer, but encourage creation of separate questions by country and encourage new answers be posted there
Owners of non-US answers can edit or delete non-US answers at their leisure. The answers were not "wrong" at the time they where posted.

No one is wrong here, we are growing as site, and it would be wrong to negatively impact anyone's rep for a developing scenario.
Comment: Rep should not be the primary consideration: beta is partially to soldify what a good question set looks like and doesn't look like. Perhaps going ahead and getting the other questions asked so that any good answers do have a home would be in order, but I wouldn't want to see non-answers left somewhere just so people earn rep.
Comment: @ChrisW.Rea: I've started the process for the Canadian answer (and sent a message to the other Canadian answer poster).
Comment: It's a logical idea. Some people will have a problem with losing rep, but it's early days on this site, and it makes sense to separate such a question by geography. I've copied my response to the original question to the Canadian version.
Comment: Agree with Caleb. I'll vote up anybody who moves their answer to the right place!  And, umm, *vice-versa* ;-) [Not that I am able to downvote, yet.] p.s. I agree let's not equate "irrelevant" with "wrong". Nobody's answer was wrong.
Answer: I have created a Canadian version of the question here. Anyone who answered the original question, but with Canadian answers, I will upvote if they answer again on the Canadian one. Once the person reaches the original upvote count I will delete the old answer to prevent duplicates.  The UK version has also been created here
Answer: I am against one more question for every country, that way we could be ending up with a possible 190+ questions. Questions which might not even differ in answer if the county involves shares some über-country wide lending system with other countries.
The correct way to handle this kind of information that evolves over time is to change the US specific question in a generic one about ebook lending then create a wiki answer where the different countries can be added and update over time.
Comment: Only Canda & UK were created because the answer were allready posted.  No one was suggesting creating the other country questions.  Any new questions or answers not related to one of 3 countries we now have questions for come in, they should be on fresh country, question.

Should this question be split?


can i split off another circuit from fuse box to run power to cigarette lighter?

Question: I am not getting any power to my cigarette lighter or to the fuse in the fuse box.  I have a 91' Ford Ranger with around 110k miles so other than that and the air conditioning it runs fine.  I was wondering if there is another fuse that I can split the power from (like the instrument panel lights) or something that would have plenty of power to charge a phone from the cigarette lighter.  Is this not something I should do?  I would just love to be able to charge my phone in my car again lol what would be the best and easiest solution?
Comment: Some people even prefer to have the cigarette lighter work on fuses that are always on.  Handy to keep the phone charged even when the car is off.  Assuming you don't leave something power hungry plugged in for too long with the car off of course!  :-)
Comment: Did you investigate why you don't get power? If you cigarette lighter is working properly you could just tap on any fuse that is activated with ignition.
Comment: No i am not sure why i do not have power to the cigarette lighter.  So your saying I can use power from another fuse, say the instrument panel or something else that would be ok if it blew while I was driving? and the watt that it would take to charge my phone wouldn't be missed and normally cause it to blow?  There is that much padding built into the circuit that it should be ok?  The old cigarette lighter may work fine but I would probably just replace it for $5 because there is a lot of crud in there from I guess cigarettes or something.
Answer: I would avoid any circuit that is currently under use.  Find a circuit that isn't used. Look for a circuit  that powers something not installed in your vehicle or not used. Your broken A/C or power window (if not equipped) circuit could be used although they won't work with the ignition off. You want to avoid adding any load to a circuit that if overloaded will make the vehicle unsafe, so stay away from lighting, wipers, turn signals etc. Check at an auto parts shop (Auto Zone, PepBoys etc) what you need is a fuse powertap. Most look like a fuse with a wire pigtailed off the fuse. That wire will be your hot or load side to the power outlet. The other wire of the outlet will need to be attached to a chassis ground.
Comment: I've used a random 12v accessory line inside the cabin to power the starter motor directly for about 4 years with no issues, The chances of you starting a fire with a low-amperage draw cigarette lighter adapter is very small. Unless you are powering a enormous inverter, but you won't be pulling that from the cigarette lighter regardless.
Comment: I have seen low load adapters melt wiring. The no brand dollar store variety are prone to shorting if twisted or abused.
Comment: But when split off with a powertap, its still on the same fuse, you might trip the fuse if whatever is on the circuit is high draw already, but you aren't wiring it up straight to the battery.
Comment: @crasic: The starter motor or just the starter solenoid? I'm a bit skeptical that you could power the starter multiple times with accessory lines without melting the wire, not to mention that you would have had to bypass the fuse to do it, since the starter takes a lot more than 10-15 amps.
Comment: @crasic you could and will blow the fuse but it will be on an otherwise unused circuit such as the power window circuit in a vehicle without power windows. The input or line side of the fuse holder will still have power, in most cases the wires will go to the fuse box but the output side wires will not be installed if not needed. The simplest means of getting the power out of the fuse box is with a fused powertap.
Comment: But will unused circuits without fuses have power going to them?  I have not looked at the back of the fuse panel yet, is there some kind of strip that supplies power to all the fuse locations (like in a home fuse box) and is it just a matter of putting a fuse in and running a wire from that spot on the panel to what you are wanting to power?  I just have never done electrical work on a a car like this before and am not sure how to go about getting the power unless it is already wired to it and I just have to split off of some junction point...
Comment: Most fuse boxes will have some empty slots with power present even if unused. You will need a meter or test light to determine which are active.


Is it desirable to compliment a seminar speaker before asking a question?

Question: Some people, when asking a question at the end of a seminar, make comments on the talk first along the lines of "great talk," "really enjoyed this talk," or similar phrases. Is this a desirable thing to do? I've noticed that most people don't do this, but some of my favorite scientists do.
Comment: Great question, @AnonymousPostdoc.
Answer: My personal preference is not to offer a compliment in this setting.  It often strikes me as less sincere (off-handed or perfunctory).  If I really want to compliment someone, I tend to catch up with them later and start with something like "I really enjoyed your talk.  If you have a minute to talk, I have a question for you about..."  On the other hand, I know that some people feel like asking questions (especially if they are critical of some aspect of the work) can feel hostile, and so they find the compliment as a good way to off-set that.
Comment: Totally agree. I groan inwards *every single time* somebody does that. Usually, after conferences, my inner voice is sore.
Answer: If it's your honest opinion, then I would compliment the talk. However, I wouldn't do it just to be polite. There is no need for false kindness.
Comment: I would only do this for a talk I liked.
Answer: When asking a question, it is desirable to explicitly establish a non-confrontational tone.  It is natural and common (though of course not correct) to interpret even well-meaning questions in an antagonistic way.  If the speaker feels threatened, they will be less able to focus on the content of the question and may instead become defensive.  A question that is interpreted as non-confrontational is therefore likely to get a better answer.
Complimenting the speaker is one way to make your subsequent question non-confrontational, and is a good idea as long as you are sincere.  Other ways include saying something nice about the topic itself ("you're studying a very interesting question"), smiling, and carefully controlling your tone of voice.  These are especially important if your question amounts to a criticism of the presented material.
Comment: Yes, and tone of voice and body language matter enormously. The relative status of the speaker and the questioner matter enormously.
Answer: I think if you reason why you compliment the person, like "I really enjoyed your talk because [state your specific reason here]", it will always be warmly accepted.
Comment: The one drawback is that insecure, literal-minded people may worry that it's an implicit insult (the talk wasn't good to praise for its own merits, but at least the subject is worthwhile).
Comment: @AnonymousMathematician My guess is that, depending on your country, it may or may not be seen as an insult.
Comment: I have edited the answer because it was too ambiguous. I meant that you should state specifically why you like the talk.
Answer: I agree with the other posters.
Personally, I try to make my tone of voice, attitude and choice of words respectful when asking a question while the conference is in session (and of course otherwise). I try to indicate indirectly that I enjoyed the talk (if indeed I did), without offering a direct compliment.
You note your favourite scientists being complimentary to speakers. I expect that these scientists are well-established, well-regarded and that they know that any praise from them would be a particular boost to, in particular, more junior scientists.
Answer: It is not desirable, but you can do it if you want. But do it shortly, because there is not a lot of time for questions after a talk.
Personally, I think that saving the compliment as a way to start a discussion later with the speaker is preferable.
To tell the truth, I also think that, except for clarification requests, questions are better asked in a discussion with the speaker, after the session. This is the only way to have complete and clear answers.
Answer: Somewhat like @Dan C suggested...
If you really felt inspired and got something new from the talk you should offer verbal appreciation. If you very much liked the presentation and is relevant to your research, it would be a good idea to talk in person.


Is it OK for me to help if I'm the asker?

Question: I posed a challenge and there are a couple answers that could easily be golfed a little more. Is it fair for me, the OP to suggest edits that would help that answer? (Or is there a neutrality rule?)
Answer: That seems perfectly fine to me, and consistent with the way most users here play. If you've got suggestions to make, make them! I've even suggested improvements when I considered the answer to be a direct competitor to an answer of my own (both in the same language).
Comment: I especially like suggesting golfs for the more verbose languages, such as Java or Python, because they are harder to golf in.
Answer: Of course it is OK. We try to be a friendly and collaborative bunch. When I see an improvement in another user's solution I point it out rather than writing my own. We I see a different approach, I write my own (time in "real" life permitting, which it hasn't much recently).
Answer: I think... if you don't know the answerer personally, give them a chance to think a little before you jump in.  Because people will post, then edit, and some of their friends they send it to will offer suggestions, and then they'll edit again... it's that expansion of the people looking at and enjoying the game that makes it fun, and you won't see community expansion if you just jump in before they can do that.
If it was your challenge you have more at stake and presumably have spent more time contemplating the problem than the answerers did.  You probably wrote a solution before you posed the problem (at least I did, in this case).
Reasonable rules would seem to be:

Creator of the challenge does not post their implementation until after they have accepted an answer.
The creator backing off a little and waiting for the dust to settle on a response, maybe a couple of days before commenting, might be prudent.  But you should definitely be able to if you see something that could use improving.


What is the difference between albedo, absolute magnitude or apparent magnitude?

Question: What is the difference between albedo, absolute magnitude or apparent magnitude? I can't really tell what's the difference between them.
Comment: Hi Angela, welcome to AstronomySE. Have you looked up the three terms on Wikipedia? You'll get a simple explanation of each term there. If you still have a question that Wikipedia doesn't answer, please use the search field to see if it's already been asked here, and if not, we would welcome your question :-)
Comment: Albedo is a property of the given body, absolute magnitude depends also on illuminating body and apparent magnitude on distance from observer in addition.
Answer: Albedo is a measurement of reflected light. It varies between 0 and 1, with 0 being completely black (reflecting no light) and 1 being completely white (reflecting all light). The albedo of coal is about 0.04, which is actually very similar to the albedo of our moon. The Albedo of ice is about 0.7. Only planets and other small objects are described using Albedo because they cannot make their own light, and so its apparent brightness is due to reflecting sunlight.
Absolute magnitude is a measure of how much light a star is emitting overall. Absolute magnitude is related to a bunch of other properties of the star, mainly how massive it is and at what stage of its lifetime it's in.
Apparent magnitude can be used to describe both stars and planets. It is simply a measure of how bright the object appears to us. An illustrative example is Sirius and Canopus. Sirius is the brightest star in the sky, but it is bright because it is close, only being 8 light years away. Canopus is the second brightest star in the sky, and appears about half as bright as Sirius, but is about 300 light years away, which means the star itself must much brighter than Sirius. If we check the absolute magnitudes and do some maths (Sirius absolute magnitude = +1.42, Canopus = -5.71, the more negative the number the brighter the star, brightness difference = 2.5^(5.71+1.42)) we get a brightness difference of 680 times between Canopus and Sirius.
Comment: IIRC, apparent magnitude also depends on the color -- stars which emit in wavelengths where our eyeball is less sensitive have smaller apparent magnitude.  // Unless I'm confusing my terminology.
Answer: Here is how I understand these terms.

Apparent magnitude is what you can see, or measure from where you really are and where the object really is.
Absolute magnitude is a mathematical prediction based on a standardized distance and configuration (see below) so that you don't have to specify the particular conditions. Venus always has roughly the same absolute magnitude because it's always roughly the same size and albedo (see next), but varies greatly in apparent magnitude be cause of changes in distance and phase angle (sun-venus-earth angle).
Albedo is a little tricky because different objects have different surface roughness and angular scattering properties. If it was a smooth ping-pong ball and had a well defined diffusivity profile, then it's easy to imagine a white, gray, or black ping-pong ball representing transitions from 1 to 0.

I've just asked Is albedo ever greater than unity? How is it calculated for various surface diffusivities and specular reflection? to get at some of those subtleties.
For stars and other objects that make their own light:

For planets, asteroids, comets, satellites (artificial and natural) and even electric cars 1, 2 that are seen in reflected light from the Sun:
Comment: I'm creating a youtube video on archeoastronomy and love the Absolute vs Apparent Brightness image. Do you know the creator of this image? I would love to use it if that's at all possible. Thank you!
Comment: @BrianRoss I drew this sketch myself (comic sans and all) in an old version of PowerPoint (note the shadows behind the circles) for the purpose of this post. You or anyone else are free to use it per the SE license (CC BY-SA 4.0)  https://i.stack.imgur.com/uHDl4.png If you have access to PowerPoint or some more modern sketching app you could probably create a nicer looking variant in only a few minutes, at which point I think it's so simple that it would not need a citation at all. Anyway, have fun!


Can I attach Trex handrail to wooden balusters?

Question: The steps to my front porch are exposed.  The treated and stained handrails have started to rot (one out of 4 rails at this time).  I am not prepared to replace all the porch and stair railings right now.  My question is whether or not it is possible to replace the 4 exposed top railings with Trex railings, attaching them to existing wooden balusters.
Answer: There is no reason you cannot mix Trex type boards/railings with wood products. Decks that use Trex type surfaces are usually framed with pressure treated lumber. If your balusters and other parts are not either pressure treated or regularly stained/sealed/painted, they will also deteriorate fairly quickly.
If you go ahead with Trex on wood, be sure to use coated screws meant for composites.

These have a special finish that resists corrosion and a special thread that grips composites well.
Some people use stainless steel, but I have heard reports of staining despite their "stainless" characteristics.
Comment: Not to mention that stainless-steel screws are softer and eaiser to strip than their coated counterparts.


How do cards improve readability?

Question: Most of the apps and websites are adapting to card design to display necessary information. What makes cards so intuitive and attractive for read/view?
Comment: I think a good answer should also list some disadvantages and explain why the advantages outweigh them. Because there is no such thing as something that only has advantages.
Answer: Some of the benefits of Cards based UI include:

Improved Scannability - Cards are neat little containers for information. They divide content into meaningful sections and thus the information is organized and well-structured.
Visually Pleasing - Cards can tease users with visual information that draw the user's eye efficiently and immediately.
Easy-on-the-eye Visuals - The content in cards are easily digestible for users thus helping in communicating quick stories.
Thumb Friendly - Behave in the same way as physical cards which makes users like its simplicity and they intuitively understand the physics of turning a card over for more information or swiping for the next chunk of information.
Good for varying screen sizes - A good choice for responsive design since cards act as content containers that easily scale up or down creating a single aesthetic across multiple devices and helps in establishing a consistent experience regardless of the device.

Reference: Cards: UI-Component Definition
Answer: The great thing with cards is the real life metaphor. All kind of cards in real life mostly are little information items that group the information of different types (images, text, etc.) in a compact way so that you can directly get the information with a short glimpse. The grouping aspect is pretty important here. It is impossible to not perceive the information on a card as a group due to the cards design. Therefore cards are a very good way to present several chunks of short information of different types (image, text, etc.) which may lead to more detailed information (e.g. like in a timeline, news feed, etc.).
Answer: Cards have multiple advantages, especially on mobile.
Physicality
A piece of text on the screen is a piece of text, but a card is an object. Users have been trained by design patterns to expect that objects can be tapped and swiped, at a minimum. If actions appear in the card, the scope of those actions is clearly delineated.
Homogenization
Cards are not just objects, but identical objects, so even though the content might vary, users can expect that it's related somehow. Users are also trained to scroll in the direction that identical objects repeat, so the affordance for horizontal scroll (think: Facebook related posts or recommended friends on mobile) is created as soon as you tile a bunch of cards horizontally and continue off-screen. The discreteness of a card object shows users that there's more content that way, even if all they can see is the card's edge.

However, the question asks about readability. As @akhilashok wrote, cards hit a few important points when it comes to scanability and information hierarchy. But none of this comes from the card. A card is just a mental model that makes it easy for designers and users to format content.
If your content doesn't look like "title, short text, maybe picture" then cards are not helpful. Material Design guidelines describe what is and isn't a card, and when to use cards. When a card is inappropriate, the extra chrome and padding distracts the user and reduces effective space on screen.

How do cards improve readability?


What's the minimum diameter cord to use when climbing a rope using a prusik

Question: If I'm using two prusik's to climb a rope (one as a foot loop and one attached to harness directly) What's the minimum diameter of cord I should be looking for to remain safe?
Comment: @Mr.Wizard Static,Tech and Nylon can all be used.  I suggest to anyone reading this to educate themselves on melting points for example Dyneema may not be suitable for use as friction hitches due to their lower critical melting point (150º Fahrenheit) as compared to polyester or nylon (350º Fahrenheit).
Comment: While Mr.Wizardss and AM_Hawk's answer already provide a great deal of information, I wanted to stress an in my opinion very important point: While all these suggestions for diameters are good and well, always test it in the field. If the prusik slips, go one more time around the rope or use alternative friction knots (there are plenty out there, some of my favourite the prohaska knot described in an answer in [this question](http://outdoors.stackexchange.com/questions/6394/how-to-arrange-2-prussiks-when-ascending-a-rope/6396#6396) or the [French Prusik](http://www.marinews.com/knots/rope-knot
Answer: I am going to approach this question differently.  Since the question is marked with the rock-climbing tag the use of a 7.5mm Technora escape rope that AM_Hawk's answer focuses on seems unlikely.  Also, the method by which he arrives at a minimum Prusik cord size doesn't address certain issues.
Cord diameter
All else being equal a smaller cord for a friction knot, such as a Prusik, will grip better than a large one.  I have seen several guidelines, such as use cord no larger than 70% of the diameter of the rope being ascended, but truly this is only a guideline.  A stiff and slick cord will have much less purchase than a limp and rough one, therefore maximum diameter is determined pragmatically by what will grip.  There are cords made specifically for friction hitches, and these typically limp cords will work better even in larger diameters than will stiff accessory cord not intended for the application.  For example, BlueWater 8mm Dynamic Prusik Cord is limper and will grip better than their 6mm Accessory Cord.
As far as minimum size, there really is none from a friction standpoint as the smaller cord grips better; it is entirely possible to use a shoelace, paracord, a string from your chalk bag, etc., so long as it can hold your weight.  One would be a fool to have these thin cords be his only attachment to the rope of course.  You can protect the ascent by progressively clipping in to loop knots in the rope, as AM_Hawk described, or you could use a non-toothed progress-capture device such as a Petzl Shunt. (Please don't implement a system without a full understanding of the devices, failure modes, and risks involved; this is merely an example.)
Perhaps you are seeking a minimum size of friction hitch that is safe as a primary connection point.  That is hard to answer.  One possible failure mode is burn-through; that is, if the knot slips the friction will melt through the cord long before you deck.  Hypothetically a smaller cord, if the loop is appropriately sized and the knot well dressed, might be less susceptible to this as it should be less likely to slip, but a larger cord stands a better chance of arresting the fall before it melts or tears through.  There is also the consideration of fusing.  Several test reports describe the friction hitch fusing to the main line after slipping; while this is less immediately terminal than burn-through it could still leave you stranded.
Resources
I was unable to find dynamic (drop) testing of small diameter Prusik cords.  However, here are some resources that seem relevant.

A test report for twin 8mm Prusiks at rescue loads: CMRU July 1997 Drop Tests.
An extensive test report for using a Purcell Prusik as a personal anchor, including 6mm cord: Rigging for Rescue -- Lanyards Part II: An Examination of Purcell Prusiks as Personal Restraint Lanyards.  (The circumstance is almost entirely different from rope ascension: the fall factors are much higher but slip is inherently limited.)
Drop testing on arborist's equipment: Ropes and Friction Hitches used in Tree Climbing Operations -- Paolo Bavaresco, Treevolution
Comment: Mr. Wizard, does your concern about the melting point of Dyneema extend to the rope as well as the cord? In my mind, there's more of a problem with accumulating heat on the cord, as it moves with the climber, picking up heat from each slide and carrying it along. On the rope, however, any one surface only contacts the prusik briefly, so it shouldn't accumulate heat in the same way. My interest is in a safety rope for my deer-hunting stand, rather than in traditional rock climbing. A smaller diameter (within the 70% parameters of prusik knots discussed above) Amsteel rope (made from Dyneema) is
Comment: @Walter Your comment appears to have been truncated.  The main rope over which the friction hitch is sliding is usually not at risk of failure -- I have never read about a case where it was the element that failed at least.  However I suppose it may be possible to produce a failure: suppose the Prusik cord is an aramid with a high decomposition temperature and the main line is Dyneema with a low melting temperature; hypothetically if the hitch slides a long way and then catches maybe it could accumulate enough heat to melt the Dyneema.  (continued)
Comment: @Walter I suspect that you will run into other practical problems first, such as having strong enough Prusik cord that grips the slick Amsteel rope.  Fall-arrest devices are usually made for thick industrial rope but there may be specialized equipment available that suits your needs.  Consider posting a Question on this subject so that the wider experience of the community may help you find a solution for your specific situation.
Answer: EDIT: When the question was posed I misinterpreted it to be asking the diameter of the "Climbing Rope" not "Cord" However my answer for Cord diameter is also listed as "2mm less than cord diameter and not less than 5mm"
I would not go any lower than 7.5mm*, it is a common diameter used by rescue technicians.There are several reasons why I recommend 7.5mm, listed below.

You need to remember and account for the diameter of your prussik, which following the general rule of thumb, is at least 2mm less than the rope diameter.  A 5mm (Static,Tech or Nylon) prussik supplies a good amount of grip.  If you chose a rope of smaller diameter your prussik will be approaching some very small diameter cord.
A 7.5mm such as the Sterling Escape Tech provides good abrasion resistance, and has the ability to withstand falls, something a rope of smaller diameter may not be able to provide.
Any smaller than 7.5mm the rope itself will be difficult to ascend, and if you chose to descend on it the rope will have a tendency to coil up and even knot itself.

*According to numbers a 6mm static cord can hold 1600 lbs however I would not recommend using it for the purpose of ascending, let's keep it for hoisting the bear barrels into the trees.
If you attempt to ascend a rope using only friction knots please use a safety back up such as the system detailed below!
As a safety precaution tie off the slack end of the rope, using a figure eight on a bite, at progressive intervals and clip to your harness. To avoid having a clutter of these knots all hanging off your harness you might choose to untie and release each previous one. Note, however, some climbers prefer the clutter to potentially getting the trailing rope snagged far below.
Comment: 1600 lbs of bear barrel, that's a lot of honey you keep in that thing!
Comment: I like the progressive interval knot idea, even though I typically have more problems with trying to get my friction knots *unstuck*, I've never had a friction knot slip on me before.
Comment: I just noticed that you linked to a 7.5mm Twin rope as an example.  So you are describing ascending two strands of rope at once?  You should be able to use at least a 6mm Prusik loop in that configuration.  I was assuming that you were referring to a single strand of Tech rope, like [BlueWater's 7.5mm Escape-Tech](http://bluewaterropes.com/home/productsinfo.asp?Channel=Occupation&Group=&GroupKey=&Category=Specialty%20Ropes/%20Escape%20Ropes%20/%20SearchLines&CategoryKey=&ProdKey=243).
Comment: @Mr.Wizard No, ascending one rope...Picked a new rope to make it clear.  Thanks for pointing that out.
Comment: When I read this I get very confused about whether you are talking about the rope on which you are placing the friction knot or the rope used to do the friction knot. It would be great if you could clarify that.
Comment: @imsodin Edit added at the top to clarify.  Thanks!


Why doesn't the alien kill Ripley in the shuttle craft?

Question: In the last scene of Alien, Ripley escapes in a shuttle craft. She screams when she sees that the alien is onboard. Why didn't the alien kill her immediately when she boarded the shuttle craft? Is it sleeping? How deaf would a 'perfect' species have to be to not hear someone scream at the top of her lungs right next to you?
Comment: The alien was stuffed from all the man flesh it had eaten earlier. This slowed down its reaction time, as a lot of people are after a big meal.
Comment: because "No one can hear you scream in space!"
Comment: @xeno_morph_not Prometheus **is** a plot hole
Comment: @Xantec it pains me to say this, but that may be the only logical conclusion so far.
Comment: Prometheus (sort of prequel of Alien) also have such annoying plot holes...
Comment: @Xantec Maybe this is only ambiguous in the extended cut with the cocoons, but I didn't see where the alien actually ate anyone.
Comment: @zabeus It's been six years, but I /think/ my comment was meant to be facetious.
Comment: I always wondered about this.
Comment: @Xantec Not to mention the mess served turkey so there was all that tryptophan in their system :)
Answer: One key reason the alien doesn't kill Ripley immediately is explained by a rather famous deleted scene from the theatrical release. The scene shows Ripley, after Parker and Lambert are killed, finding a still-alive captain Dallas, who they all had assumed was killed earlier by the alien. In fact, Dallas had been cocooned by the alien, along with Brett, and they are each gradually mutating into one of the original eggs that birthed the facehugger.
This illustration of the original plan for the alien life-cycle shows that the alien doesn't need to kill everyone, and in fact shouldn't have the need to kill everyone in order to adequately propagate the species. If the alien were a blood-thirsty, mindless killing machine, this life-cycle would be hindered. The same can be said for aliens in the second movie, who also cocoon victims, but in that case they cocoon them so they can be "facehuggered" later from eggs laid by the Queen. So, whether or not this deleted scene is considered, as a rule an alien wouldn't be expected to kill every victim so that it might keep the species going.
However, the alien will need to kill for food or if threatened. It probably wasn't hungry as it had grown to full size and had killed Parker and Lambert just prior. And consider just how easily the alien had dispatched the rest of the crew, even the ones with flame-throwers. Those soft, pink creatures with no innate weapons or defenses and relatively poor senses and reflexes are hardly a cause for worry from the aliens point of view. Add in the fact that the escape pod was a very compact space (i.e. advantage alien) and the alien likely didn't feel that Ripley was even a remote threat to it. It could conserve its energy and take its time. Once she started blasting it with gases, it changed its mind.
Comment: actually, the version I saw the other day **was** the uncut version (only fools watch theatrical releases of Ridley Scott movies). That being said, you would still think the alien would attack/bite/slap around or otherwise manhandle Ripley. The alien just lies there for no reason.
Comment: @puk: As an out-of-universe explanation, it most likely was just a plot device for the purpose of suspense. I was just trying to give the most reasonable in-universe explanation I could think of for the behavior of the alien.
Comment: It still feels like a plot device to me because the alien is just lying there all defenseless.
Comment: Another out of universe answer could be that the production team might not have been able to manage large, quick movements with the alien while it was tucked into the small alcove on the shuttle. IIRC it didn't exactly move fast in the open corridors of the ship either, for similar reasons.
Comment: @Xantec wow that was bad. I thought the alien was going to puppy lick her face
Comment: @Xantec: True, a 7 foot tall guy in a latex suit with a giant headpiece can't move all that quickly or gracefully, which is probably why they also cut [this scene](http://www.youtube.com/watch?v=eR5jYeIMBKk) from the theatrical release.
Comment: @puk: I added a little more reasoning to the last paragraph to address your point.
Answer: The alien was, iirc, huddled on its side in a small alcove.  It may have actually been sleeping, or in a minor hibernation state, as we saw in the sequel Aliens that the aliens stay motionless in their natural environment, invisible to both thermal and motion sensors, until roused.
Another possibility is that it was preparing to molt.  We had already seen shed skin from it as it rapidly grew.  Even though it appeared to be quite large, it is possible that it was resting in preparation for a (final?) molt.
Comment: I could see the molt explanation working
Answer: I have three theories on this.
Theory one: after Ripley started the self destruct sequence the ship went berserk with warnings. Perhaps the Alien realized that its environment had changed for the worse and wasn't entirely sure what it needed to do to survive.  The logical thing to do would be to watch how its surviving quarry behaves.  In fact, this is exactly what it does; it lies low, follows Ripley and observes.  Killing her just because she screamed would not have aided in its survival;  keeping her alive and riding shotgun to safety would.
A second possible explanation. Let's say for argument's sake that the Alien, like ourselves is hardwired for survival and propagation. It was young, hungry, enthusiastic and confused when it killed the other crew members but when it matured it must have realized that Ripley was the only living thing in its Universe that could host new Aliens. It was probably more interested in keeping her alive for cocooning/implanting than ripping her head off.
My third explanation is that the creature didn't hear her or didn't understand her. Consider, in Alien Resurrection the imprisoned Aliens communicate with each other to coordinate their breakout but they don't use sounds (possible pheromones or some kind of telepathy).  It is possible that they do not have any kind of auditory senses.  Even if they do, the only sounds they make themselves are that horrible screaming so hearing it from a completely unknown life form may not have been a clue that it had been discovered.
Comment: They did the same thing in the second movie, "Quietly gaining passage off the now-flaming-rock." – [How did the queen get on to the ship in Aliens?](https://scifi.stackexchange.com/questions/145802/how-did-the-queen-get-on-to-the-ship-in-aliens)
Comment: I think both (1) and (2) are very reasonable. (3) is meh, not needed.
Answer: This is not a "huge question left unanswered". The only question that needs answering is why you guys think that just because an Alien isn't stuffing victims into its mouth like it's a hotdog-eating competition, something must bewrong with it. It's broken, mommy! Jeez, can't an Alien take five once in a while? It just ate. The crew.
Okay, look. The Alien is a species that has managed to spread to different planets without developing tools or technology. It does this by acting as a parasite on other species. In the sequels, Aliens ride elevators and cut power lines. Is it really such a stretch to imagine that an adult Alien might be smart enough to conserve its host species until it is needed? Lions follow herds across the plains, killing them to feed themselves or their cubs, but never for sport.
The Alien followed Ripley and her cat onto the shuttle, because that's what a predatory organism does when a herd of prey migrates. It follows. Casually. No rush. If you drop two mice into a snake's cage, the snake might eat one, but will always save the other till later, not even looking at it. This does not mean the snake is incapacitated or "defenseless", nor does it mean the snake hasn't noticed the mouse.
I'm not saying the Alien is a reptile specifically, but think about it: It would be an extraordinary coincidence if Ripley's ship stumbled onto the crashed spacecraft containing a nest of alien eggs soon after it crashed. Far more likely the crashed spacecraft, and the eggs, had been there for a very long time, centuries even. Yet the eggs were still active. This suggests the sort of energy-conserving rest mode we see in many reptiles, and bugs like fleas.
To sum up, the Alien was resting, saving Ripley and her cat for later, biding its time until another herd of human food comes along, from wherever herds of humans come from in this little metal universe. Then the alien got gassed, and it decided (correctly) Ripley probably had something to do with it.
Comment: LOL   /end rant  ;-)
Answer: I guess you are talking about the first movie, Alien.
This Alien-creature is not old. It gets "born" after eating its way out of her coworker, and is only a few hours old. It gets to full size in about 15 minutes.
Any young creature who feels like it owns the universe will at some point think it is invincible. I think that this is what happened to the Alien. It felt it had killed all the others fast and "easy", and when the last person screams it starts to take its time, for the fun of it. Like a cat who isnt hungry starts to play with the mouse before killing it.
Comment: @puk I don't see any claim that the alien "goes comatose after every meal" in this answer.
Comment: That an intergalactic species goes comatose after every meal is pure speculation
Comment: I think the timeline you are discussing here is a bit compressed - i think we are talking a few hours to a day or so not 15 minutes, whilst the engineers fix the ship and the rest of the crew hunt the creature that they do not want to be onboard whilst they hibernate.
Answer: I always assumed that the reason the Alien didn't immediately jump out and eat Ripley was because either:

It could tell that she was the last human, and would be required for egg placement later.
In maturing so quickly, it's mental comprehension had also developed, and the Alien picked up on the fact, perhaps from Ripley's behavior, that the area they were in was the only safe place during a tragic event, and chose to stay hidden.  Scared animals don't tend to hunt until danger has passed.

And a less probable explanation that I heard was interesting - The Alien might not be fond of spoiled food, and was leaving the helpless pink human animal alive until the Alien was hungry again.  As several have pointed out, it had just eaten quite a bit earlier that day.
Answer: It was waiting until it was sure Ripley had sent the ship off safely?  It knew that it was going to get blown on the ship and needed her to set the escape pod off into space.
Answer: The alien was coming to the end of its life cycle, when Ripley happened
  to disturb it.  It was slow to attack because it was dying.  This theory is
  supported by an older version of the ALIEN script where Ash reveals that
  the alien had made a nest and ensured the continutation of its species
  (cocooned Dallas and transformed Brett into an egg) at which time the alien
  itself would approach the end of its lifecycle; curl up and die.
Comment: ^This. I remeber reading interview with Ridley Scott - he originally planned for Aliens to have a very short life cycle, bit like mayflies: spend long time semi-dormant as facehugger in the egg, then after impregnating someone, quick, brutal life of an adult xenomorph who not only eats, but makes more eggs (via morphing his still alive victims).
Answer: The alien has a quick, short life cycle. In the shuttle, it appears to be more gooey and a different color than before. It probably was dying, or it could be resting until it needed food or another host- just because I have a refrigerator full of food does not mean I eat it all in one sitting.
Comment: https://avp.fandom.com/wiki/Alien_(film). You're right, it was meant to be dying. Also, Ridley Scott wanted the alien to kill Ripley, but the producers nixed it so... here we are
Answer: XX121 The reason why they did not kill Ripley was because it was tired from the killing and was dying. The XX121 killed the entire crew besides Dallas, Brett and Ripley within 24 hours. But Dallas and Brett got cocooned. What I am saying is it was using a lot of energy. Also a xenomorph's life cycle takes an estimated amount of 2 to 3 hours. The xenomorph's life span however is about 20 to 24 hours. The xenomorph was dying and Ridley Scott made XX121 die on purpose. The xenomorph was dying and wanted a quiet place to die. To prove this Ridley Scott made the movie to where the XX121 died quickly.
Comment: Do you have any evidence for the figures and theories you state here that you could [edit] in to back this up?
Answer: No no no!
The alien doesn't even notice her!
It is ill or something. It is completely shocked when Ripley turns on the high pressure jet on top of it and doesn't wake up when she tries the first two jets. It is kind of moaning in its sleep when she sees it and screams.
I think it's either knackered or naturally dying as it has a very short life cycle and has (maybe) impregnated Lambert therefore completing its purpose.
Comment: Further - I think it's a massive question left unanswered and can't believe there aren't more discussions on the www about it.
Comment: yes it was very vague, and, IMHO, not Deliverance vague, which was intentional.
Answer: It might be  really tired, because the reactions of the "chestburster" come in after it turns into a "xenomorph drone" and this is the first time the "chestburster" bursts out of the rib cage of our species. Also another reason it didn't kill Ripley is because it was evolving into a xenomorph warrior and evolving into another stage is tiring and exhausting for xenomorph.
Answer: The Alien had impregnated the cat. That done, it wanted to make sure that the cat would safely reach a population of other living creatures, be it humans or animals or any other species. It figured out that the only sentient creature that could do that (i.e. navigate the ship and reach home safely) is Ripley. So it wanted her to stay alive until the ship reached its destination and another Alien companion would emerge from the cat's body. The two of them would then have greater chances of impregnating other creatures, starting a new colony of aliens.
I believe also that the Alien was in a state of hibernation, in which its senses, movements and general aggression might be muffled.
Comment: Impregnated the cat?! How? And what evidence is there to support that?
Comment: @gnovice - The old-fashioned way I imagine... ;)


what is the argument for not using the average of an average?

Question: I want to disprove someone's calculation of percentage of cash sales for a year by taking summing percentage of cash sales by month and dividing by 12.  I sense the correct way is to take total cash sales for the year and divide by total sales for year to arrive at percentage of sales but need correct reasoning why it is wrong to use an average of an average.
Comment: What is 'percentage of cash sales'? How is it calculated?
Answer: You need a counter example.  E.g.
<code>Mon     Sales   Cash    Percent

Jan     100     70      70%
Feb      10      1      10%
Mar      10      1      10%
Apr      10      1      10%
May      10      1      10%
Jun      10      1      10%
Jul      10      1      10%
Aug      10      1      10%
Sep      10      1      10%
Oct      10      1      10%
Nov      10      1      10%
Dec     100     70      70%
</code>
Total sales are $300$, cash sales are $150$ so the overall percentage is $50\%$. But the average of the monthly percentages is $20\%$.
Comment: Thank you very much. I will be back to this site I'm sure.
Answer: You are correct, here's a mathematical example:
Let $s_1, s_2, s_3 \cdots s_{12}$ be the sales of the months.
Let $c_1, c_2, c_3 \cdots c_{12}$ be the cash sales of the months.
Then your question is if:
$$ \frac{1}{12} \sum_{k=1}^{12} \frac{c_k}{s_k} $$
Is the same as:
$$ \frac{\sum_{k=1}^{12} c_k}{\sum_{k=1}^{12} s_k} $$
You can show it is false by plugging in some numbers.
Comment: Thanks for taking the time to respond.  Very helpful.
Answer: The average of the averages leads to the right average only when the samples have the same size.
If each month has exactly the same number of sales, then taking the average of the averages would be right. But if the number of sales per month is different, then the average of averages leads in general to the wrong answer.
Simple situation:
First month 100 sales of 1 each. Average 1.
Second month 1 sale of 100. Average 100 .
The average of the averages is 50.50, but there were 101 sales and only 200 income....
Comment: Right, otherwise you need a weighted average. A simple unweighted arithmetic mean would be wrong.
Comment: Thank you very much.   Language very helpful.
Answer: Suppose in January I sell \$100 worth of product, and all of it is sold for cash. Every other month I sell \$1 worth of product, and none of it is sold for cash. I have then sold \$111 dollars worth of product, of which \$100 was sold for cash, so my percentage of cash sales is $\frac{100}{111}\approx90\%$. Calculated the other way, we would get that for $1$ month $100\%$ of my sales were cash, while for the other $11$, $0\%$ of my sales were cash, giving $\frac{100\%}{12}\approx 8.3\%$. This is clearly wrong.
Comment: Thanks so much for responding.  Examples are so helpful!
Answer: It is clear to you that taking cash sales for a year, and dividing by total sales for the year, will give you the correct proportion of cash sales for that year.
The problem with taking monthly proportions and averaging them (average of averages) is that that procedure could produce a quite different number.
Let's take a simple numerical example. January to October: total sales each month $\$1000$, cash sales each month $\$500$.  November and December (Christmas season, people are buying a lot, mostly on credit): total sales each month $\$10000$, cash sales each month $\$500$.
So total sales for the year, 30000, cash sales 6000. Thus the yearly proportion of cash sales is $\dfrac{6000}{30000}=20\%$. This is the correct percentage.
Now let's compute the monthly averages. For January through October, they are $50\%$. For each of November and December, they are $5\%$.
To find the average of the monthly proportions, as a percent, we take $\frac{1}{12}(50+50+50+50+50+50+50+50+50+50 +5+5)$. This is approximately $42.5\%$, which is wildly different from the true average of $20\%$.
For many businesses, sales exhibit a strong seasonality. If the pattern of cash sales versus total sales also exhibits seasonality, averaging monthly averages may give answers that are quite far from the truth.
Comment: Exactly what I needed! Thanks very much.


text messages forwarded from my google voice number aren't recognized as being from my iPhone contacts

Question: I set up my google voice number to forward to my AT&T number, but when I get texts from some people who are in my contact list, the text appears to come from phone numbers I don't recognize.  The text message itself will be prefaced by the phone number the text is coming from, but even though that number is in my contact list, the message does not offer me the name of the person.  I have an iPhone 4 and I'm running iOS 6.1.  Any help is appreciated.
Answer: This is, unfortunately, a limitation of Google Voice. Google Voice cannot spoof your friends' numbers, so it has to send texts from its own numbers. However, each of your contacts will have a unique number from which Voice will send you texts, so you can send messages to those numbers and reply to them and it will reach your friends.
There are two ways around this. You can use the Google Voice app. Messages will come through your data plan and not your SMS plan, and they'll show up with the right names and everything. Alternatively, you can add the numbers Google uses as the "from" address as another number in your iPhone contacts. The number will still work to reach them, and the messages will appear to come from your Google Voice number.
Comment: Hey, thanks for asking for clarification. This issue is not about sending, it's about receiving. I can use SMS GV Extension when sending to ensure that other people see my correct GV number when they receive a text message from me; but what I'm trying to fix is what I see in my Messages app when I get a text message from someone else to my GV number.
Comment: THIS IS NOT A LIMITATION OF GOOGLE VOICE. It is an isolated issue that happens only to some people, not to other people. I have checked with multiple other GV users with iPhones and tested it with them: when I send a text message to their GV number that gets forwarded to the iPhone Messages app, it shows up with my correct number, NOT a GV direct access number.
Comment: Are you sending from your own GV number? Because in that case, Google *does* own your number, and can forward it on to the destination with your GV number and not a forwarding number.
Comment: cablesm is mostly correct, although I would add that some people consider this a great feature rather than a limitation, because it gives you a "shortcut" number for each person.  You can add those numbers to your address book, then use them in the Phone app to make calls too. But it is true that when GV forwards an incoming text to your cellphone, it cannot spoof the sender's real number unless the sender is using GV also.
Answer: As google has shown in this link, this is a normal feature of Voice.
You have your Voice account set up to forward messages to your phone (from google). Unless you have a phone number at Google Voice, you will receive the messages from one of the random phone numbers that Google owns.
It is stated many times on the net that if you get the Google Voice app, it will show you the actual number of the sender; rather than the number assigned to forward the messages to your phone. This should eliminate the issue.
Answer: The problem is not a normal feature of Google Voice (nobody else has ever experienced it, to my knowledge, except the original poster of this question). It was not caused by Google Voice settings. It was not caused by Google Voice iOS app. It was not caused by Messages app. It was not caused by SMS GV Extension. It WAS caused by Google Contacts sync. I fixed the problem simply by deactivating Google Contacts sync on my iPhone and then reactivating it a minute later.
Please stop editing this answer to remove the important explanatory material in the blog post I wrote about the issue. You are not helping anyone by hiding this information.
Comment: Those edits were unnecessary and, in any case, far too aggressive. Why don't you edit the wrong answer that has all the upvotes instead?
Comment: Sorry if the edit seemed too aggressive to you, but please keep in mind that answers should focus on directly answering the question and not on discussing other answers. If you do not agree with answers given by others, please use the means provided by the site (downvote and/or leaving a comment at the respective answer) to give feedback.
Comment: Nevertheless you put a lot of effort into your analysis before coming to a conclusion, something I consider worth keeping on the site. May I ask you to edit the answer yourself and trim it down to the facts relevant for the situation?
Comment: I can't downvote other answers or comment on them because I don't have any reputation points left, because I used them all to create the bounty, which attracted people to come and hastily write wrong answers in the first place.
Comment: Nevertheless please restrict your answer to the facts and don't use it to comment other answers. Bounty will go to the accepted answer (or the one with the most upvotes) anyway.
Answer: The reason the texts come from a strange number is so that replies will go back through google and appear to come from your google voice number.  If the texts came from the real users phone number, when you sms'ed back, it would be from your iPhone's phone number, and not from your GV number on their side.


Why does an ice cube not twirl along when twirling a drink glass?

Question: When you have a drink with an ice cube and twirl the glass, the liquid itself seems to twirl but the ice cube stays roughly in the same place. Why is this?
Comment: When you say "twirl," are you just rotating the glass about it's center (ie. spin it)? Or something more complicated?
Comment: I think that this would first only induce the surface of the water to tilt, since it is trying to orientated to the normal of the resulting acceleration. However the water is not rotating at first, just as the ice cubes.
Comment: @tpg2114 Yes, just rotating it about it's center.
Answer: Your assertion that spinning the glass causes the liquid in it to also spin may contain only a grain of truth and a lot of optical illusion. It is extremely difficult to see the motion of water or even just the exact position of its surface; especially with calm water, this is a frequent cause of misjudged landings for pilots of sea or amphibious planes. What we do perceive is the shape, waves, and ripples of the surface of the water. These shapes tend to move very differently from the water that forms them, because water simply rising and falling may give the illusion of a wave moving forward (if water in front starts such motion at a slightly later time).
What likely happens is that a tiny amount of the spin you impart on the glass gets transferred to the water. Hence you see some indication of it rotating, which your brain may easily mistake for it rotating with the glass because it is so hard to tell (and what other likely speed is there for visual reference?). The ice cube, however, makes it obvious how slowly it is spinning. And it may very well spin at an even slower angular momentum because it, too, must first be accelerated by the limited amount of hydrodynamic friction.
May I propose an experiment where you sprinkle your water with small particles just big enough to be seen as individual markers? Perhaps some small bits of paper could do the trick. That should make it reasonably obvious how fast the water at the surface is spinning.
Comment: You can see this if you try to mix a layered coffee in a transparent glass. You can see layers, and they have features so you can see whether they rotate, but if you swing the glass around and create a wave on the surface, the layers just wobble a bit, they don't start to spin.
Answer: To get the ice cube to twirl by pure twirling of the glass, there need to be viscous stresses applied to the ice cube from the spinning water.
To simplify matters, lets say that the water in your glass is perfectly still before you start twirling, that the ice cube is away from the edge of the glass, and that the twirling is initiated smoothly so that there is no sloshing of the water in your glass.  Now, as the glass begins to spin, it pulls on the water immediately adjacent to its boundary which will spin at the same rate as the glass without slipping (this is called a no-slip boundary condition).  However, the glass cannot directly cause the water away from this boundary to move.  Instead, viscous stresses have to transmit momentum from the boundary towards the centre but, as water is not very viscous, this takes time.  In the (presumably) short amount of time you twirl your glass, there simply may not be enough time to get the ice cube to start spinning also.
However, if you really need to get your ice cube spinning or swirling around inside your glass in a hurry, creating a "slosh" wave is probably the best way to go about it.
Answer: If the liquid were really rotating in the glass, the ice cubes would rotate with it. What you are (probably) seeing is the superposition of two perpendicular resonant waves sloshing back and forth, but not rotating.  Here is how it works:
Imagine that, instead of moving the glass in a circle, you just move it back and forth in an east/west direction.  This would cause the liquid to slosh back and forth.  Molecules near the edge would go up and down, but not move side-to-side very much.  Any floating ice cube would also move up and down, but not move side-to-side much.
Now imagine that you move the glass back and forth in a north/south direction (instead of east/west as above).  You will get a similar result as before, with the molecules (and any floating ice) mostly moving up and down, with only a little north/south motion.
Now imagine you do both at once.  If you get the phasing right, the east/west wave will peak on the east side; then the north/south wave will peak on the north side; then the east/west wave will peak on the west side; and finally the north/south wave will peak on the south side.  In other words, the "peak" will appear to rotate in a circle around the perimeter of the glass--but the molecules (and the floating ice) are still mostly moving up and down.
This is the same phenomenon that produces circular polarization in an electromagnetic wave.
Comment: I very much like this way of looking at the situation. What causes the change from this behavior you describe to when the ice starts following the rotation at a higher rotational velocity?
Comment: @Zach Saucier: If you hold the glass in you hand and move it in a circular pattern, you are not really "spinning" it--you are "translating" it.  The circular pattern can be thought of as superimposed north/south and east/west linear sinusoidal translations.  True, if you do that hard enough, the liquid will flatten against the side of the glass and start flowing around the perimeter.  You can actually get the ice to rotate that way.  But for smaller amplitude movements, the motion of the liquid (and ice) is mostly up and down, with little rotation.
Answer: When you stir the contents, everything in the cup gains angular velocity including the ice cubes. Centripetal acceleration causes less dense materials to accumulate at the center of rotation as the denser materials force their way to the edge of rotation. If the angular velocity is high enough, this edge can rise against gravity, causing the water surface to curve into a parabola. All of this is exploited in the laboratory equipment known as the centrifuge. Since ice is less dense than water it will tend to collect in the center of a stirred cup.
Comment: Actually, floating ice will not preferentially accumulate at the center of a spinning vessel of water, because the mass of the ice is exactly the same as the mass of the water it displaces.  If the ice were not floating (ie, you filled a closed container completely with water and put in some ice, and spun the container), then the ice *would* drift toward the center as you suggest.
Comment: @DavidRose, have you done an experiment? The floating ice is not entirely equivalent to the same mass of water, since some mass is above the water level.
Comment: @Jan Lalinsky; No I haven't' done the experiment.  But others have.  Floating ice (actually, any floating object) displaces exactly it's own mass in water.  One way to prove it is to float some ice in a bowl, and fill the bowl with water right up to the rim.  As the ice melts, you might expect the water to overflow the bowl.  But it doesn't.  Since the mass of the ice didn't change when it melted, and since the melted ice took up exactly the same volume as the frozen ice displaced, you can conclude the ice displaces its own mass in water.
Comment: One slightly off-topic real-world ramification of the ice melting discussion: If all the ice floating at the north pole were to melt, it wouldn't affect sea level at all.  The only way melting ice would affect sea level is if ice that is currently on land (Antarctica and Greenland, for example) were to melt and flow into the sea.
Comment: @DavidRose, that's interesting in itself, but I do not see how that invalidates colinharper's description. The ice cube feels the same buoyancy force as the water, but has different mass distribution. Its center of mass is above the center of mass of displaced water and on the parabolic water surface this may result in net force pulling the ice cube to lowest height.
Answer: In short, the movement of an ice cube in water lags relative to the movement of the container because the ice cube's viscosity is sharply higher than that of the surrounding water.
The effects of inertia might be more easily imagined by simplifying the components to a slowly-melting ice cube sitting on a smooth/flat platter.  If the platter is slid briskly North for a distance for distance X, then the ice cube travels somewhat less than X.
In both cases, the water acts a lubricant decoupling the motion of the container from the ice cube.
Answer: When you rotate a glass of water about its axis, only the water at the sides of the glass which is in direct contact with the glass rotates along with it initially, as water has a high force of adhesion with glass, which is stronger than the forces of cohesion between water molecules.
The rest of the water which is not in direct contact with the glass rotates with a far lesser angular velocity whose magnitude decreases as we move towards the centre of the water surface. At the very centre, the velocity is zero. This is similar to the fact that the "eye" of a hurricane is the safest place to be if you are caught in one!
The surface of the water aligns itself perpendicularly to the resultant acceleration vector so that the surface of the water tilts inwards towards the centre and hence an ice cube placed in a glass of water, on rotation of the glass, tends to move towards the centre of the glass where the angular velocity is almost zero (I am saying almost zero since the ice cube isn't a point mass. It covers some surface of the water so it may acquire a small angular velocity which is negligible at the beginning, but after some time becomes observable).
I must also add that the rotation of the ice cube becomes visible only after some time because the coefficient of friction between ice and water is very small, hence the angular acceleration is very small.
Answer: Let us make an mental experiment. Suppose that there is no friction between the glass and the water inside. In this case, if you rotate the glass, the water inside and the ice cube will just stay still. This is because the angular momentum of the water and of the ice cube is conserved, since in this case no torque is applied to the water, i.e., there is no force twirling the water and the ice cube.
Without friction, twirling the glass has no effect on the ice cube, which stands still in its initial position.
The question at this point is why, if the angular (twirling) speed is high enough, the ice cube starts to move?
Suppose now that the water is frozen. In this case, the glass and the water is a rigid body, and therefore if you twirl the glass, you twirl the frozen water altogether.
If the water is not frozen and you take into account friction, you realize that the twirling glass and the friction between the glass and the water will result to a small applied torque to the water inside, and as a consequence to the ice cube (due to the friction between the ice cube and the water). Therefore the ice cube will start to twirl slowly.
The angular momentum of the ice cube after a fixed time is roughly proportional to the friction between glass and water, water and ice cube, and to the angular momentum of the glass.
Since the friction is indeed very small, if the "twirl" speed (angular momentum) is not fast enough, you are not able to appreciate any "twirling" of the ice cube.
Also if you rotate the glass back and forth, clockwise and anticlockwise repeatedly, the torque is applied each time in a different direction and for a very short time, and therefore the torque applied to the ice cube has literally no time to accelerate the ice cube.
If you make the glass rotating in the same direction for a time long enough, you will be able to see the ice cube twirl (this is in principle how centrifugal machines work).
Comment: Granted this answer could have been more concise, but someone's downvote-without-critique seems overly harsh.
Answer: The coefficient of friction between the glass and water is high enough so that by twirling your glass, the water gets dragged along and starts twirling too.
However, this seems not to be the case for the coefficient of friction between the water and the ice cube. Thus, the water cannot drag the icecube with itself (or cannot drag it aswell as the glass drags the water : maybe if you keep twirling long enough the ice cube will eventually start spinning too)
Comment: This doesn't seem like a likely explanation. If that were true, you would get flow around the cube with the cube remaining stationary. This (1) doesn't seem intuitive at all and (2) doesn't match what I've observed playing with glasses of water+ice.


Removing unwanted files from Windows Folder

Question: Some software when installed puts some files in the Windows folder (or directory). This sometimes results in losing a large amount of disk space. How do I manually remove those files that don't get deleted even if you run the un-intsaller? Is there any software which cleans the Windows folder from unwanted files?
Answer: Well about how much disk space are we talking? If a program installs some DLLs you might never use again, that won't cause any trouble.
I personally would refrain from using any program that deletes something in the Windows folder. Unless you are 100% sure what you are deleting, I just wouldn't do it.
Apart from that, CCleaner is a decent tool!
Answer: The software that I use to keep my PC clean from junk is: Advanced System Care, and CCleaner  With the Advanced system care there is a third party uninstaller than may take care of those "lose" files.  Give them a shot and see what you think.


Effect of magnetic field on electronic components

Question: Are electronic components like diodes,transistors, micro-controllers, microprocessors, wireless transceivers etc are damaged by strong static or dynamic magnetic fields? If yes, at what strength the field becomes dangerous? Also, what are the ways to protect the components against such fields?
Comment: What frequency components do the dynamic fields have?
Answer: Static field effects on devices
Strong static magnetic fields will have little effect on most electronics, including most of the ones on your list.  We routinely placed basic electronics in 1-2T fields, and never had any real problems.  There are some exceptions though (this is probably not a complete list):

Relays work by using a magnet to move a piece of ferrous material to close a switch. Strong fields may open them, close them, or get them stuck in whatever position they are in.
Inductors and transformers have magnetically soft cores, which couple magnetic flux much better than air.  They are designed for a certain flux density based on the properties of the coils in them, and beyond that they saturate, becoming less effective.  The field they create adds with the external field, so the external field can cause early saturation. This reduces the inductance of inductors and ferrites, and reduces the efficiency of transformers.  It may also introduce harmonic content in transformers.
Hall sensors obviously measure magnetic field, and will measure the external field.  Watch out for them in motors and in some sensors.
LVDT position sensors probably won't be remotely accurate in an external field.
Motors almost always use magnetic fields internally and may or may not work. They tend to have half decent shielding, so you may be pleasantly surprised.
Magnetic recording media such as hard disks, tape, floppy disks... are very suceptable, but also usually well shielded (particularly modern hard disks).  So will usually be OK.

If you have any items in the above list, it would probably be wise to check with the manufacturer with your specific field strength and field gradient.  Or look for alternatives.
Shielding static fields
You can shield against static fields with magnetically soft materials and careful geometry.  The cheap way is to use iron plates or tubes.  Mu-metal is a more expensive but also much more compact and effective option.  The most effective shielding is a series of concentric tubes aligned along the field direction, with the delicate electronics inside.  In the unlikely event you have a cryogenic system, superconductors also make excellent shields - wrap things in lead foil.
Dynamic fields
These are very complicated, so I'm not going to give a complete answer here.  Broadly speaking, they are rather worse than static fields of the same strength, and may cause all sorts of problems with any electronics.  If you give a rough guide to field strength and frequencies, I might be able to add more.  A few Hz can be treated as above, hundreds of Hz will be more complicated.
Dynamic fields can be shielded by a combination of the magnetically soft iron described above and highly conductive metal sheets. The soft iron works well at low frequencies, and the copper sheet at high frequencies.  Top end shielded rooms use alternating layers of mu-metal and copper, with air gaps.
Comment: hello, It is a very good reply to the title question,  but in the content the focus was more about 'damage' and microelectronic components. also harddisk are not very sensible to magnetic fields, only to degaussers (alternative magnetic fields)
Answer: For protection : a Faraday cage.
Comment: I don't think that will work for static fields.
Answer: Electronic components such as the list you provided will normally not be damaged by any magnetic field, static or dynamic.
Let still note:

A magnetic field can influence the electrical property of your devices, it is difficult to really define strength, (depends on a lot of parameters) but you could consider some impacts already at 50KG (~field of a fridge magnet, ~100 times earth magnetic field). This means the devices may not behave as you would expect but still will not be damaged and will work again once the field is removed.
If that is a concern, most devices are already protected against charge accumulations (due to antenna effects)
other electronic devices magnetic based (for instance hard disks) are nowadays not very sensible to static magnetic fields, you can have a look at this question/answer
If the field is really too strong you may have some physical damages, but it will not happen at device level but rather on the connections/packaging


What is this seedling?

Question: This is growing in my backyard. Is it a maple? It looks a little maple-y, but Google Image comparisons were inconclusive, and there aren't any maples nearby that might have dropped a seed.
Answer: This looks like maple, could be Acer pseudoplatanus. But hard to be sure at this stage. You could update with more photos when leaves are completely unfolded.
By the way, I am not sure if this is a seedling though. It could be in its second year already since I don't see any cotyledons.
Comment: To clarify, A. pseudoplatanus is called a Sycamore Maple, which is rather rare in the US and Canada. If you live in North America, the seedling could also be a true sycamore ( Platanus occidentalis), which has interesting bark when it gets older, or a Norway maple (A. platanoides). It's definitely a yearling, not a seedling. Where do you live?
Comment: Northeastern US.
Comment: I didn't realize the Sycamore Maple is rare in the US, here in Europe I think it is the most commonly spread out in the wild. Usually when I find seedlings of Maple here in the Netherlands, they are the Sycamore kind. If you have more mature leaves, you could see the differences, I remember a previous [post](https://gardening.stackexchange.com/questions/35813/acer-platanoides-vs-acer-pseudoplatanus) here on SE.
Comment: In the UK *A. pseudoplatanus* is just called the Sycamore, without any reference to "Maple". It is actually the third most widely distributed tree species in the UK, after Ash (before Ash dieback disease took hold) and Hawthorn - and has a bit of a reputation of being an invasive weed.
Comment: Since you live in NE US, it IS possible that you have a Sycamore Maple (New England are really the only states they're found wild in - and then only in a few counties). Of course, you could have a seedling of a domestic tree. Check out the USDA's Plants Database map: https://plants.usda.gov/core/profile?symbol=ACPS and see if your county is in the light blue (click on the map and then scroll and/or move the cursor)

What is this seedling?


Is it more effective to lead with a physical conflict rather than an emotional one?

Question: I currently have the choice of two routes with my novel - to lead with a knives-and-poisons main conflict, with reference to the protagonist's emotional conflict, or to lead with him conquering his inability to manage his peculiarities (OCD, etc) while untangling the plot. I understand that both will influence the other, but is there a best practice with which one to lead with?
Answer: The heart of a story is neither physical conflict nor emotional conflict, it is moral conflict. That is to say, it is about the character being made to face a choice about values. Does pride and prejudice win out over love? Does Spiderman save MJ or the busload of children?
Emotional conflict results from moral conflict. Moral conflict forces us to pay a price to attain a goal. There is an emotional cost to paying the price and an emotional gain from achieving the goal.
Physical conflict arises because two characters have different, non-compatible goals. This poses another moral conflict -- am I willing to engage in violence to achieve my goals.
So, in the hierarchy of conflicts, moral conflict is at the top, emotional conflict is in the middle, and physical conflict is at the bottom. Physical conflict alone is not very interesting. The interest comes from the emotional conflict and, more fundamentally, the moral conflict.
This does not mean that you have to do a full exposition of the moral conflict, followed by a full exposition of the emotional conflict, followed by a full exposition of the physical conflict. But it does mean that the reader needs to see at least the seeds of the moral and emotional conflict before you can expect them to engage with the physical conflict.
Comment: What? Morals? Gosh, Mark, you must be about my age, and I've already forgotten about morals in literature. Get with it! Same with epiphany and all that stuff. I'd lead the story with action. Use characters that are so stereotypical that they are easy to digitize for animation. Have a mindless plot that is so easy to follow, you won't lose track when your spouse packs up and leaves. How else are you going to get movie royalties? Remember, a lot of assigned literature in colleges (those being books that sell, by force) are used as examplars of obsolete morals.
Comment: It seems obvious now that you say it . . .
Answer: I think that depends entirely on your story and the initial mood you're trying to establish (both for the story and between the characters).
Starting with a physical conflict is a fairly easy way to quickly draw your reader in. It's the cheapest way of creating dramatic circumstances: Raise your reader's pulse quickly in order to demand their focus.
If you start with an emotional conflict or backstory, you gamble a little with their interest in that plot line. It's harder because this way you need to convince the reader that this is both dramatic and interesting, while two dudes fighting or a battle scene does that almost implicitly.
So what should you start with? Well, what is the tone and speed of your story? Start high quickly (and then take the reader on rollercoasters) or slowly build up and increase tension over the course of the first act?
The final answer to your question is: There is no "best practice", just what suits your particular story progression.
Answer: I think the really important conflict is between the world inside a character's head and the world outside of it. Since "the world outside of it" is usually shaped by other characters acting in accordance with their own model of the world, this almost always has a moral dimension (because that model of the world will include a model of how people should behave in it), a physical dimension (because they will physically interact with things) and an emotional one (because they will have invested their emotions in aspects of their world model).
My view is that a story is, at its simplest level, about a character encountering something that doesn't mesh with their understanding of the world, and having to make a choice between changing the world or changing themselves. A story generally ends when the relevant aspect of the world and the relevant aspect of the character's understanding of it are in alignment.
So, think about who your character is, what they believe and what they want, and think about the sort of conflict that really defines the start of their story arc. Whether that ends up being physical or emotional is usually irrelevant; it's how it relates to the overall story that really matters.
Answer: I think that depends entirely on the nature of the story.
At the extreme: If the story is all about a person's emotional struggles, throwing in a gratuitous fight scene to try to grab the reader's interest seems counterproductive to me. It will mislead the reader about the nature of the story and put him in the wrong frame of mind.
Even if the story includes both physical conflict and emotional struggles, if it's mostly about the emotional struggles and the fighting is an outgrowth of that, starting with a fight scene might be a way to begin with high drama, but it could also be misleading and distracting.
I suppose it's easier to grab a reader's attention with a fight scene. You don't need to know much about the characters to understand it. A scene about a character's emotional struggles may require some background. But not necessarily. A story that began, "Bob decided that his only choice was to kill himself" would probably grab the reader's attention without knowing anything about Bob. Indeed if I read that as the first sentence of a story, I think I'd immediately be asking, "Why does Bob want to kill himself? What happened to him?" etc.
I'd add that in my humble opinion, fight scenes and car chases and the like work very well in movies, but not nearly so well in books. It's hard to capture the action and tension with printed words. Not impossible, but hard. I often find myself skimming over fight scenes in books with a "yeah, yeah, I get it, they had a fight".


Setting wget permission to 755 so users other than root can execute it a big security risk?

Question: I read recently in blogs that by default wget on linux is 750, so only root can execute it. I would like to allow users wget and change it to 755, but I read around the web that it is a big security risk..
Comment: You can't believe everything you read on the Internet. Though I'd love to see one of these blogs.
Answer: Setting the permissions to 755 is no security risk. The security risk is, if you have software installed that have bugs (for example a blogging software, or other dynamic websites) evil people may use wget to download malicious software to your server.
I advice you to use something like grsecurity/rsbac, selinux, ... or to make it simple, just use the permissions right.
Create a group "wget". Do a chgrp wget /usr/bin/wget. Set the chmod to 750. And put every user that is allowed to execute wget into the wget group.
But don't put a service/daemon user into that group (like apache, mysql, ...).
Answer: Wget can be used to download files when one will manage to do code injection. Wget itself is not a problem, but the websites with holes, which allows to run it.
This is security thru obscurity and web app should be secured with SELinux, AppArmor and IPTables, that it's impossible to download files, as one can initiate downloads using PHP functions or other software which can be uploaded to the server.
Answer: On the CentOS 5,6 and Ubuntu (various) systems I have to hand wget has 755 perms, so 750 isn't the default for all Linux distros.
As to the security risk, wget will allow users to download arbitrary files but so will quite a few other utilities which come as standard.


How many bullets can Deadpool's guns carry?

Question: In the movie Deadpool, on the bridge fight scene, Deadpool says he only has 12 bullets. But those weapons looks like Desert Eagles, and he has two. So that means they only have six round capacity?
Comment: The weapons pictured here are Desert Eagle, but I don't know why caliber it is. The .50 has a 7 round capacity and the .44 has an 8 round capacity. Why he only has 12? Maybe he shot a few previously. Maybe he only loaded 12?
Comment: @DustinDavis He just came from a cab ride just to wait for the bad guy. I dont think he shoot any round before that, but that is one possibility. Btw if you dont watch the movie highly recommend, just saw it yesterday.
Comment: @DustinDavis But thanks for confirm is a Desert Eagle, my only experience with weapons is from *Call of Dutty* ;)
Comment: @JuanCarlosOropeza is that Indian version of COD? I see many people named dutta/dutty in India ;)
Comment: @Vishwa Nope just a typo. And english isnt my first lenguage
Comment: @JuanCarlosOropeza Just kidding. Thanks for the your inputs :)
Answer: From my research for the Can a single bullet from a handgun kill three people in the way Deadpool did? question, he seems to have not fully loaded his weapon.
From IMFDB:

Deadpool (Ryan Reynolds) can be seen dual-wielding IWI Desert Eagle Mark XIX pistols as his primary firearms, using them to great effect. His Desert Eagles are current-production Mark XIX models with over-barrel Picatinny-style rails made by IWI in Israel. They are recognizable by their safeties, which are retained from the original production Mark XIX; the U.S.-made Magnum Research version, in contrast, now has the "teardrop"-style safety found on the original Mark I.
The Desert Eagles used in the films are chambered in .50 AE, based on shots of the shell casings (with .50 AE clearly visible) and the lack of fluting on the barrels. Strangely, they are apparently not fully loaded, as he states he has "12 bullets" in the highway fight. He shoots 7 rounds from the gun in his left hand and 5 from the one in his right hand, meaning one gun was fully loaded and the other wasn't. Desert Eagle handguns in .50 AE hold 7+1 rounds. Also, at another noteworthy point, every primer of the spent casings are marked with the number of the round spent (from 12 to 1).

The +1 being a round in the chamber. A 7 round clip is the standard package for this gun, and Deadpool was not using an extended clip. The standard clip even has the rounds numbered on the clip (4, 5, 6, 7).

The extended clips stick out from the bottom of the gun.

As we see multiple times, for budget reasons, I mean Wade have ADD, he often forgets his weapons, so he likely forgot to load the gun up all the way.
That, or as mentioned in the comments, he shot some off before the cab ride.
Update:
You can clearly see a real clip used in the movie. It has the 4, 5, 6, 7 holes. Deadpool just underloaded the weapon.
Comment: the more you live the more you learn, I knew IMDB, didnt know they need IMFDB
Comment: wow, did you watch the movie again to get that picture with the underloaded clip?
Comment: @JuanCarlosOropeza ha no, I was googling for a good picture of the clip and found it. And its on IMFDB too. I never scrolled down all the way.