#### Sun, 21 Sep 2014 04:46:22 +0000

*Doctor Who*, "Time Heist", and... it was good. I actually don't have any serious complaints.

What the hell, Moffat?

#doctorwho

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So I watched the latest *Doctor Who*, "Time Heist", and... it was good. I actually don't have any serious complaints.

What the hell, Moffat?

#doctorwho

What the hell, Moffat?

#doctorwho

TL;DR: On average, if you have sex regularly, you will eventually get pregnant... Regardless of what birth control you use.

**Original Post from Yonatan Zunger:**

**Sex and Probability**

Today it's time for a lesson about sex and the basics of probability theory, because *why not?* It's also going to be a great opportunity to annoy many people: some of you by telling you that your favorite method of birth control, the one you've known and loved for years, doesn't actually work very well; some of you by advocating birth control in the first place, since birth control is secretly a form of abortion (it isn't); some of you by advocating birth control in the first place, because sex is a terrible thing and should only be done for procreation (I hear you, recognize what you're saying, and have nothing useful to say to you; you should probably just move on); and some of you by advocating probability theory, because mathematics is just an *inappropriate subject* for delicate young minds such as your own.*

* It has been rumored that thinking about mathematics can cause women's uteri to migrate uncontrollably. It may also lead to bicycle riding and the wearing of pants, and thence to the collapse of Western civilization. You have been warned!

So for those of you who have not yet run away in abject terror, let's take a look at this lovely graphic produced by Gregor Aisch and Bill Marsh at the NYT, showing how likely various birth control methods are to fail. They bring up an important point: normally, when you hear about the success rate of some method, it's given to you as two numbers -- the probability of failure per year when used perfectly, and the probability when used "typically." The difference between the two can range from minor to catastrophic, as you can see from the graphs. (The dotted lines are "perfect," the colored ones are "actual")

However, most people don't just have sex for a year and then decide it's not really for them; most people are happily shtoinking away for decades at a stretch. And in that case, you might ask yourself, what are the odds that this system will fail after *ten* years?

At first, you might make the obvious naïve guess, that it's ten times the odds of failure per year. But something's obviously wrong with that, because (for example) the rhythm method fails 24% of the time in a year, so that would give you a 240% chance of having a child in a decade. While this may put you on a good path to having the 2.4 children of a typical family, it doesn't sound like actual probability theory.

So let's do the math properly, and then let's talk about birth control methods. This math is useful because once you know the basic methods of probability, you can use them for all sorts of things. (Mathematicians often use "giving someone a lesson in probability theory" as a euphemism for "cleaning them out at blackjack," for example. I promise that's not what I'm going to do below.)

A probability is a number between zero and one which tells you how likely something is to happen, if you try it a huge number of times. Zero means that it will absolutely never happen; one means that it will always happen; and any number in between tells you that it will happen that fraction of the time. (A probability expressed as a percentage is simply 100 times the probability expressed as a decimal)

Probabilities obey two simple rules:

1. If you have a list of all the possible outcomes of a single test, the sum of the probabilities of those outcomes is one: that is, *one* of those things has to happen. In particular, if you're looking at the probability of a yes/no question, and the probability of a "yes" is p, then the probability of a "no" has to be 1-p.

2. If two events are independent of one another (e.g., flipping two coins), then the probability that both will happen is the product of the two probabilities.

Now, let's say that we want to find out if your birth control will work for ten years. You go to the manufacturer and find that there's a probability "p" that it will fail each year. (For example, 0.02 for a perfectly-used male condom, or 0.18 for a "typically" used one) Now, what's the probability that it will succeed for ten years straight?

Well, that's simply the probability that it will succeed in the first year, and in the second year, and the third year, and so on. The probability that it will *succeed* in each year is 1-p, by our first rule; so the probability that it will succeed in all of the years is (1-p)(1-p)...(1-p) = (1-p)¹⁰. Or (using our first rule again), the probability that it will fail at some point during those ten years is simply the probability that it won't succeed for ten years straight -- that is, 1-(1-p)¹⁰.

Note what I didn't do: I didn't say that the probability that it will fail in any of the ten years is the probability that it will fail in the first year, plus the probability it will fail in the second year, and so on. In fact, there's *no* simple rule for the probability of an "either" statement: instead, whenever you work with probabilities, you convert it into a "both" statement like I did above.

The general rule: the probability that either A or B will happen is one minus the probability that neither A nor B will happen. "Neither A nor B" is simply another way of saying not A and not B, so that's simply the probability of (not A) times the probability of (not B). And by our earlier rule, that's (1-A) times (1-B). Or if I phrase that in terms of math,

P(A or B) = 1 - P(neither A nor B)

= 1 - P(not A and not B)

= 1 - P(not A) * P(not B)

= 1 - (1-A) * (1-B)

= A + B - A*B

Note that this is *almost* the naïve guess of A+B: there's just that extra term, - AB, which basically comes from the fact that if both A and B trigger, then it only counts as triggering "A or B" once, but A+B counted it twice. If A and B are both numbers much smaller than one, say they're each 0.01, then A*B is even smaller -- 0.0001 -- and so you can ignore it. But when the total probabilities start to get close to 1, this makes a difference.

So that's how you calculate the probability that something will fail if used repeatedly. To reiterate, if the probability of failure each year is p, then the probability of failure after ten years is 1-(1-p)¹⁰. And that's what was graphed below.

So now, having done some math, let's talk about sex. (This is also the point where I'm going to upset you by telling you that your favorite method doesn't work. Sorry.) The numbers below come from the manufacturers, who have a fairly good reason to want the failure rates to come out low -- but even they can't make them look great.

In fact, we can break these methods into four groups by eyeball:**The ones that reliably work:** The bottom row of the graph, hormonal implants, IUDs (both Levonorgestrel and copper), and sterilization, obviously reliably work, even after ten years. Hormonal implants have only a 1% failure rate even after that long. More importantly, these methods show no difference between the "used perfectly" and "used normally" graphs, something which I'll come back to in a moment.

Some things to be aware of with these methods: sterilization is not, generally, reversible, so if you only want temporary birth control these two are out. IUD's have some rare side effects which you should talk with your doctor about -- however, the horror stories that you may associate with them have to do with the very early models made in the 1970's. This was resolved 40 years ago, and today they're considered very safe. Hormonal implants have an extremely low rate of side effects, and are the most reliable of all.**The ones that "work" in a loose sense of the word:** The Pill, the Evra patch, the NuvaRing, and Depo-Provera. These have excellent success rates if used perfectly (2-3% failure rate after ten years!), and *terrible* success rates if used normally. (60% failure rate after ten years!)

A marketing executive from these companies will tell you that these work wonderfully. Speaking as an engineer, this is utter bollocks. A system that works well when operated perfectly and fails completely when anything isn't operated perfectly is basically the textbook description of what a safety system *isn't.* And in all of these cases, "perfect use" is a much tighter definition than you may be expecting: failure to take a pill at the correct time, or not realizing that another medication that you (or your partner!) is taking cancels out your pill, are the two most common kinds of "imperfect use" which move you from one curve to the other curve. (A large fraction of all oral and topical antibiotics will cheerfully deactivate most oral contraceptives, for example.)

They do have their upsides -- for example, the Pill can be more easily tuned (trying different prescriptions) to find the one that works best with your body. But if I tried to sell you a car and told you that, so long as you keep it in perfect maintenance (you always check your tire pressure before each drive, right?) the brakes will work *just fine,* you would be awfully suspicious of me. For a good reason.

This brings us to...**The ones that "work" in only the most abstract sense of the word:** Withdrawal, the rhythm method, and the male and female condom are sort of like the previous category -- they work *much* better when they're done perfectly. Unlike the previous category, though, even when they *are* used perfectly they're incredibly unreliable: in perfect use the best of them (the male condom) will still fail 18% of the time after ten years.

These methods are also the ones most famous for not being used properly, because "perfect use" isn't as simple as it seems. For the male condom, that means storing the condom at the right temperature range and replacing it regularly, avoiding any (even indirect) genital contact before putting it on, using correct lubricants, not using it for too long, withdrawing immediately after ejaculating, bracing the base of the condom properly during withdrawal, and making sure that no semen gets anywhere (including on your hands) during the cleanup process.

In short, these are not good methods *at all* for avoiding pregnancy. However, two of them -- the male and female condom -- *are* good methods for avoiding STI's (and in fact, they are the *only* ones on this list which will do anything at all about that!) and so there is very good reason to use them. However, if you're serious about preventing pregnancy, you should use them in *addition* to other methods, not *instead* of them!

The other two methods on this list -- withdrawal and rhythm -- are not serious methods for avoiding pregnancy; at best, they are methods for reducing its frequency. However, the rhythm method in reverse, also known as the "basal-temperature method," *is* the best place to start when you're trying to get pregnant.

And finally, we have**The ones that do not, in any meaningful sense of the word at all, work:** Spermicides, the sponge, and the diaphragm are absolutely terrible at preventing pregnancy. I have to admit that I'm impressed that anyone is willing to market, as birth control, something that when used *perfectly* has an 89% failure rate over ten years. That's not an advertisement for birth control; it's an advertisement for a fertility treatment.

Also, none of those methods protect against STI's.

Now, after reading through this list, what can we learn?

If you're trying to avoid becoming pregnant or getting someone else pregnant, then by far your best bet is hormonal implants, sterilization, or the IUD. Unfortunately, only one of these is available for men right now, and it's the non-reversible one, but people are working on it and hopefully we'll have some improvements soon.

The various methods in the middle are significantly flaky, but if you combine enough of them they can work. (Again, you can do this with probability theory. Say you use both a condom and the Pill, both "typically." You'll only get pregnant if both fail -- so the probability of that in a year is 0.18 * 0.09 = 0.016. After ten years, our previous formula then gives a total failure rate of 15%, compared to 86% and 61% for using them separately.) Don't rely on any one of them alone.*However,* and this is extremely important, don't forget that STI's exist and are a very serious problem. Condoms (and dental dams, and other related barriers), used correctly, protect against them. If you aren't in a completely monogamous relationship with a fluid-bonded partner, or aren't engaging in the sort of extremely rigorous continuous testing regime that porn actors do, then you need to be using them. This is in addition to whatever you're doing to prevent pregnancy!

And on a final note: Sex and probability can be fun. Consider working this into your time with your partner: can you build a model of the probability of orgasm after N strokes (or licks, or caresses, or so on)? Can you use this to work out how the probabilities must be changing with each successive stroke, that the next stroke will be the one to push your partner over the edge?

This will probably work best if both you and your partner are tremendous geeks. But on the other hand, if you just read an entire article about birth control and probability theory, the odds of that are pretty good.

This is the video that catalyzed Marcus "Notch" Persson's decision to sell Mojang to Microsoft. It's fascinating and educational.

Now, let's everybody hate on Innuendo Studios for making a now-famous video about how people on the Internet hate on people who get famous. It'll be so meta!

#minecraft #internetculture #videogames

Now, let's everybody hate on Innuendo Studios for making a now-famous video about how people on the Internet hate on people who get famous. It'll be so meta!

#minecraft #internetculture #videogames

Seeing the photos, I think it's pretty obviously, at the very least, the Sontaran costume. #doctorwho #scifi #wildspeculation

**Original Post from Christine C.:**

+Kevin C. The Silence makes more sense for other scenes, but I still think it's a Sontaran in the bedroom. I put this together in Photoshop. Notice the straight smooth nose, the square eye sockets and the very wide head. If you look carefully you can also make out the eyes, which are not as deeply set as The Silence's are. "Hiding" under a blanket would fit with a Sontaran under orders to remain undetected. Also, it could tie into the Doctor yelling "The Sontarans! Perverting the course of human history!" I think either that's meant to be a Sontaran, or they simply used that costume so they'd have something "spooky" to show.

Financial freedom doesn't mean all the moneys are belong to you. It's about realizing... There is no money.

The money is a lie.

Or something.

The money is a lie.

Or something.

Hello, big brother. Why yes, I am so very happy that you are here to protect us by watching our every move. Of course I am. Thank you for asking.

#privacy #politics #tech #freedom #anonymity #facialrecognition #surveillance

#privacy #politics #tech #freedom #anonymity #facialrecognition #surveillance

So at the end of my last post about this, I made a somewhat radical guess as to what might have really been going on in the latest episode of

.

.

.

When the Doctor describes "perfect hiding", he's actually describing the Silence without realizing it. The answer to his question, "listen", bolsters this: The Silence, after all, were created as confessors.

The entire episode follows a child Silence who has somehow ended up aboard the TARDIS trying to communicate with the Doctor (presumably, to warn him of some catastrophic plot that will come to fruition in the season finale). That's why the answer to his question is in his own handwriting, but he doesn't remember writing it. That's why young Rupert Pink in the window doesn't look particularly scared, when Clara and the Doctor have first arrived, but by the time Clara gets up to the room, he's seemingly seen something that spooked him. That's why the mysterious figure in his bedroom stays under the blankets: Because it wants to be seen, but if they get a good look at it, they'll forget. When the blanket does come off, though shown for only a split second and out of focus in the background, we see what appears to be a short, squat figure with a large bald head, dark eyes, and pallid, gray-ish skin... Just like the Silence, only child-sized.

Moffat is always trying to be clever, and this wouldn't be the first time he's tried to sneak in major plot points in ways that looked innocuous (the future Doctor's words to Amy in

Either that... Or Moffat's given us a one-off half-baked shaggy dog story about the Doctor jumping at his own shadow that rehashes old themes he's already mined to exhaustion. I'm honestly not sure which.

#scifi #doctorwho #fantheory

+Benjamin Nash pointed me to this fascinating and powerful little short story over at the Crossed Genres ezine. It's a bit hard to describe, but basically explores one idea of how people with extreme motor control dysfunctions might use technology to communicate with each other in a new way.

#scifi #stories

#scifi #stories

So I just watched the latest episode of

.

.

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The episode opens with the Doctor postulating that evolution should have created a "perfect hider", and asking an empty room what it does. The answer (and episode title) appears on his chalkboard: Listen.

Now, perhaps I'm being a bit arrogant in saying this, but I would think that, as a brilliant 2000 year old pacifistic alien traveler of time and space, the Doctor would interpret this the same way I did: As an unknown life form trying to engage in a dialog. But he doesn't. He's terrified of what he doesn't understand, like some pudding-brained human.

Let's stop here for a second to postulate what a "perfect hider" might be like -- remembering, of course, that we've already conceptually separated it from a "perfect predator". So we're not talking about some kind of predatory assassin-type, but just something that stays hidden. How does something stay hidden? Fundamentally, hiding is all about avoidance. Avoid being seen. Avoid being heard. Avoid confrontation or engagement of any kind. A perfect hider's entire psychology would have to revolve around this. It would have to be passive and non-aggressive, because direct confrontation would be completely against its nature.

Am I making a bit of an assumption there? Maybe. You could argue that if the perfect hider

Add to that an opening scene where this unknown being seems to want to communicate with the Doctor, not threaten him, and I really couldn't get into the creepy tone the episode seemed to be trying so hard to create.

There's some attempts at spooky backstory about everyone throughout history having the same nightmare about someone under the bed grabbing their ankle, some side plot with Clara on a date, and pretty soon we end up in an orphanage where Clara, the Doctor and a little boy are cowering before... a silent figure under a bed sheet. As the Doctor so succinctly puts it, there are two possibilities: Either it's one of the other kids playing a prank, or it's not.

The Doctor clearly assumes that it's one of his hypothetical "perfect hiders" and jumps to the conclusion that such a being would be dangerous and aggressive if it were seen (I've already expressed my doubts about that), despite the fact that they're all clearly staring right at it for a good length of time and it makes no threatening moves of any kind. He further decides that, obviously, logically, the best course of action when faced with a presumed dangerous sheet monster that clearly already knows you've seen it is to

You know what's a really terrible way to hide? Sitting upright under a sheet in the middle of a well-lit room with people in it. The only reason a perfect hider would do something like that is if it

The sheet monster comes up very close behind them, and I'm not sure if we were supposed to find this threatening, or if we were supposed to notice that it was the same height as the little boy and start to think it was going to turn out to be a prank. Either way, the sheet slowly comes off in the background, and we get only an out of focus, split second glimpse of what was underneath, but it was pretty clear the coloring and proportions are not that of a human child. It was too brief and blurred to see much, but the impression I got was of something along the lines of a classic grey alien.

The next encounter happens on the last planet at the very end of time (haven't we seen a couple of these before? how many can there be?), when the Doctor unlocks an airlock and something begins opening it from outside. We never see what, but the Doctor gets knocked out, Clara is terrified, and she manages to fly the TARDIS to... well, she doesn't really care where, she just wants to go anyplace else. Fair enough.

So where does she end up? Under the bed of a little boy in what appears to be a 19th century barn... Who is apparently a young Time Lord. She immediately assumes (as did I and most other viewers, no doubt) that this is the young Doctor. This initially seemed like a raging plothole (Gallifrey being time locked and all), but I'm going to actually give Moffat and company the benefit of the doubt here for once and assume that the obviously old fashioned, Earthly look of everything was actually supposed to be a cue to the audience that this wasn't taking place on Gallifrey, but during some kind of space/time excursion from the Doctor's youth. This raises a lot of questions about exactly what "time locking" means, but that's a topic for another day.

So anyway, the young Doctor starts to get out of bed and to stop him, Clara reaches out from under the bed and grabs his ankle. The big "twist" turns out to be that the scary monster under the Doctor's bed was Clara all along.

On the surface, this episode appears to be an entire hour of watching the Doctor jump at his own shadow. He freaks out because he's spending too much time alone in the TARDIS and then goes through a series of ambiguous but vaguely creepy scenes that all have alternate "perfectly reasonable explanation" interpretations: the Doctor wrote on his chalkboard and forgot, there was just a kid under the sheet playing a prank, and the knocking at the airlock was just, I don't remember, the hull decompressing or something. And apparently, it's all because Clara accidentally scared the Doctor when he was a little boy.

At least, it seems like that's the impression the audience is supposed to be left with. And if that's all that was going on, then I guess it was a perfectly acceptable if somewhat underwhelming standalone outing.

Except... My wife and I were discussing the episode afterward, and we came up with a very different interpretation. Here's where the wild speculation begins: What if the entire episode is actually about a baby Silence trying to communicate with the Doctor?

#doctorwho #scifi #twelfthdoctor