When I was a kid, I had and loved a chemistry set. It was by no means perfect -- the book it came with was terse and rather uninspiring, and so I ended up finding later bits of Science! that I did much more interesting, things involving electronics, radioactives, superconductors, and pyrotechnics. But it was a good set, with a wide range of materials and equipment, and it was part of a whole complex of other things which were part of the "standard set of toys" of the latter half of the 20th century, along with LEGOs, erector sets, and any number of other building toys, which made doing science and engineering and the like seem like a natural thing you would explore as a kid.

This article suggests that the turning point was in the 1970's, with the rise of ecological consciousness, the anti-war movement (and opposition to things like Napalm and Agent Orange in particular), and Three Mile Island, but I don't think this is right: I got my set in the 80's, and it was by no means an unusual thing then.

I think that the real turnaround happened somewhat later, in the 1990's or 2000's, and was part of the general trend of increasing protectiveness of children: the same trend which would make the normal way I played as a kid (my friends and I roaming all over the neighborhood, exploring, playing games, and the like) into criminal negligence on the part of parents today. (You let children play unsupervised?! What if they were injured? What if they were kidnapped?! This despite the near-complete absence of actual stranger kidnappings ever) 

Chemistry sets like these are nearly nonexistent, with the exception of rare boutique products like the (wonderful) Kickstarter which this article links. It in fact surprises me that such products are illegal at all -- and as the Kickstarter text notes, it may in fact be illegal in quite a few states, not because of the chemicals, but because of the glassware. (Apparently, civilians can no longer be trusted with beakers; we might use them to make meth. Chemists probably can't be trusted either, as they might use them to make Sudafed: http://heterodoxy.cc/meowdocs/pseudo/pseudosynth.pdf) 

There is something profoundly broken in this. Anything which could conceivably create a risk to anyone, or which a Hollywood plot imagines could create a risk, is becoming illegal. The media actively encourages this, knowing that its bread and butter is stoking fear of all sorts.

It's time to fight back. We need more interesting hazards in our lives.

Via +Alex Scrivener.

Unlike the E-Cat scam that was making the rounds earlier this week, this new announcement from Lockheed-Martin -- that their Skunk Works team has been working on a compact fusion reactor which may be at the working-prototype reactor stage within five years, and productionizable a few years after that -- is actually quite interesting. They haven't broken any laws of physics: this is a magnetic-confinement fusion reactor, and their advances have been clever engineering and coming up with smarter ways to shape the confinement fields. 

(For those who know the subject: the details aren't 100% clear to me, but it looks like they're building a pair of magnetic cusps facing one another, and using a Polywell-like approach to "bounce" plasma off of those and into the center where the fusion happens. Which is not an insane design)

Rather nicely, the people doing this design have actually thought through how it would fit into existing power architectures. (Very few people working on fusion have any experience with that) They expect the units to stay around the size of the device you see in the photo below -- truck-transportable nodes, each producing around 100MW. One could run a ship; a building full of them, or perhaps more conveniently, several different buildings in different places, could run a city. (As my experience in deploying big hardware has taught me, having your system take the form of a bunch of identical medium-sized nodes is really wonderful. If the nodes are too small, you spend all your time dealing with how to wire thousands of things up; if they're too big, then your smallest quantum of deployable capacity is a pain in the ass. 100MW is just about perfect for power generation.) 

If this system works, it would have nearly immediate commercial viability; opex plus fuel for such a device is very low (less than any other kind of power plant running, even if you consider dumping pollutants into the air as absolutely free). Capex for early generations won't be cheap but won't be prohibitive, either, as you can buy in 100MW increments and easily scale up. Maintenance is straightforward. Direct pollutants are zero: the only waste product is Helium. (Probably not enough to be worth selling, but you could fill some party balloons) There's an indirect pollutant, in that the neutron absorber shell which gathers the energy from the reaction will gradually be activated and turn radioactive; this shell will probably have to be replaced every twenty years or so, but (especially with clever choice of materials) isn't actually that radioactive and isn't that much material, either.

There have been lots of fusion designs which have seemed promising in the past, but this one seems to have a lot of engineering good sense behind it, and contact with practicalities. That makes me interested.

So it's still far too early to be popping the champagne corks, but it's a promising design being put together by serious people, and so I'd say that it has a decent chance of actually going somewhere. 

Another cool "how things are made" video: the process of making a good-quality knife, starting from base matter. This looks like fun.

The Gods of the World: A group called "The 40 Foundation" put together this rather extraordinary infographic of the world's religions and how they're (historically) related to one another. It's a phylogenetic tree of the gods.

I can't say that this diagram is complete, nor that it shows every possible cross-pollination; it would be very hard to do so, given just how intricate this aspect of history is. Likewise, it's hard to define the boundaries between various sects, at times; while the Protestants are very famous for each sect having its own name and being firmly opposed to those schismatics from the Popular Front of Judea, many other religious divisions have been more subtle, two groups simply moving away from each other over time, or one group simply adopting a radically different theology without telling anyone. But the image is detailed enough that you can clearly see phenomena like the Protestant Reformation, the emergence of Islam, and quite a few other historical events very visually. And to nitpick a work this complex feels almost petty.

You can view single images at the link, or a zoomable version (with an admittedly crappy UI) at http://funki.com.ua/ru/portfolio/lab/world-religions-tree/ . 

h/t +Alex Fink for finding this.

In grade school, you probably learned about the average, also known as the mean. You may have learned about other numbers, like the median and the mode, which also characterize how things are distributed. These numbers, however, tend to conceal more than they reveal: when you really want to understand something, you look at a curve called the distribution instead. That curve is simply a plot of how often each possible outcome occurs, and all of the numbers above -- numbers called "measures of central tendency" -- can be calculated from that curve, and summarize various aspects of the curve.

The reason that professionals care about the curve more than the numbers is that the curve is full of secrets of its own. One of the most interesting secrets is what's called "universality:" it turns out that there is a very small set of shapes, and almost every distribution curve you actually encounter in the world, whether you're measuring the frequency at which people use words, or the time it takes to get through a checkout line, or the number of marmots in a field, turns out to have one of these shapes. 

(Or more specifically, real distributions are almost always combinations of these shapes, say a bump of one shape here and a curve of another shape there. That always means that two distinct things are going on, each contributing a single shape, and it can be one of the fastest ways to understand how the system is really working.)

Why are distributions more interesting? Apart from being able to read the secrets of their shapes, the problem with just looking at numbers is what they hide. There's an old joke about two guys in a bar in Seattle, grousing about how broke they are, when Bill Gates walks in. One of them pauses for a sec, thinks hard, then jumps up and yells "Drinks are on me, everyone!" His friend asks him, "Are you crazy? I thought you said you were broke!" "No, I just did the math! On the average, everyone in here is a millionaire!"

So let's talk about these shapes a bit more. There are four particularly common shapes. (There are a few others as well, but 99.5% of the time what you see are combinations of these four)

The first is the Gaussian, or bell curve. Gaussians generally happen when there's something that happens roughly the same way every time, and the deviations from that "same way" are completely random and uncorrelated noise. For example, if you measure how long it takes you to walk down the same hallway every day, the distribution curve will probably be a Gaussian. The position of the center of the bell curve tells you the average, and its width tells you how frequent random disruptions are.

The second is the exponential curve. This looks like a sharp spike followed by a decay. (Specifically, a decay shaped like F = e^−(ax), where x is the value that we're measuring, F is the number of times we saw x, and a is a constant) This is most often a sign of queues. For example, if you measure how long it takes to read a small file from a hard disk, and do it over and over again, the frequency distribution of times will look like a Gaussian added to an exponential. Why? Because the time it takes to read from an idle disk is a Gaussian -- there's a random amount of time it takes the head to seek to the right position, and then it takes a constant amount of time to do the reading. However, if the computer is busy, then you have to wait in line before that can start, and it turns out that the distribution of the time it takes to wait in line is almost always an exponential. (That fact is something we regularly use in computing to identify when the problem is that things are getting stuck waiting in line)

The third shape is a power law. This looks sort of like an exponential, but it has a much heavier tail. (The formula is F = (x/x0)^−a, and if you plot it on a log-log chart, it looks like a straight line) Power laws turn out to be extremely universal whenever humans are involved: for example, if you look at a large body of text and ask "what fraction of words show up frequently versus rarely," the shape is a power law, no matter what language. (In that case, a is about 1.8, in case you're curious. Syntax words like "and" and "the" are the most common, obscure nouns like "zymurgy" are among the rare ones, and there's a long tail of words that basically appear only once in a corpus) But power laws show up all over the place: look at the number of pictures people take each week. Look at the number of friends people have. Look at the size of cities. 

It turns out that there are some fairly deep reasons that power laws are so common. For example, imagine you're looking at a network -- say, the phone network, or the network of people's friends. If a network formed by "random attachment," that is, any new node that shows up is equally likely to attach to any other node, then the distribution of how many neighbors everyone has is a Gaussian. But if it forms by "preferential attachment," that is, a newcomer is more likely to attach to someone who already knows a lot of people, then you can show mathematically that you get a power law. Lots of real networks do this: new people in a social group, for example, are more likely to start out by meeting the really gregarious person at the middle.

(This is really important for practical applications, too, because preferential-attachment networks have all sorts of other interesting features. For example, a random-attachment network doesn't become disconnected (no longer joining everyone) until you blow up a lot of links. A preferential-attachment network, on the other hand, can disconnect very quickly if you lose the very central nodes. If your network is the Internet, then you really want to keep things from being disconnected, so it's important to know what parts are the most critical. On the other hand, if your network is the graph of people who were in physical contact with each other (a preferential-attachment network), which also happens to be the graph along which contagious diseases spreads, you might be very interested in making this network disconnect: that tells you that investing your money in making sure that contagious diseases don't spread through the people with the highest number of connections is a much better bet than trying to protect everyone equally. It turns out that immunizing a hermit doesn't do nearly as much as immunizing, say, the janitor of a large building.)

And then there's a fourth common shape, the Tracy-Widom Curve. This one looks sort of like a skewed bell curve, Gaussian on the left and exponential on the right. It shows up all over the place as well, especially when studying systems with a lot of strong interactions amongst themselves. However, we don't really understand why it's so common yet: it's proven a tougher nut to crack than the power law. 

However, there's been some recent progress: it turns out that this curve may be happening whenever there's a certain kind of phase transition behavior in the system, similar to ice melting or water boiling. And this article will tell you more about that.

The key takeaways are:

* Distributions matter! Averages and so on lie, because they hide things. If you really want to understand something, always demand the distribution.

* Distributions always seem to be combinations of a handful of standard shapes. If there's more than one shape in a distribution, you're seeing several different physical processes at once, and each shape tells you a story.

* There are four standard shapes, and we understand three of them pretty well and know how to read stories from them: Gaussians telling you about random events, exponentials about something waiting in line, power laws about humans or biology being somehow involved, or about preferential attachment, or a few other similar things. There's a fourth one which we're only starting to understand, but it keeps showing up, too.

* Statistics is cool, because it reveals the secrets of the universe and helps you fix problems.

Via +Jennifer Ouellette​​.

For those of you who have been waiting for it: the formal announcement of Android L (Lollipop), the Nexus 6, the Nexus 9, and the Nexus Player, which is our new streaming media player.

Having had a chance to actually play with test units of these, I have to say that they're pretty awesome in all sorts of little ways I hadn't anticipated. I would have thought that the 6, for example, would be too big -- but it's surprisingly pleasing to work with, and there's been a regular report from people who use the test devices daily that afterwards their old phones feel weirdly small and uncomfortable by comparison. The Player is really cool as well, but I can't tell you all of the cool stuff of that yet. :) (I haven't yet had a chance to play with a 9 -- but I will, yes, I will.)

The most complex watches are extraordinary works of art. I'm not talking about the gaudy status symbols, ones which try to show off the wearer's wealth by encrusting themselves in diamonds; I'm talking about devices which are simultaneously pieces of sculpture and the highest refinements of the mechanical arts, trying to push the limits of elegance in a small region.

I can't imagine that, even if I did have a spare couple of million dollars lying around with which to acquire such a device, I would ever wear it; this is something which from the moment of its completion looks like it belongs in a museum, where the public can see it, watch it move, and listen to its sounds. But I very much enjoy watching the process of its creation, and the device which comes out at the end of it.

"How things are made" -- really complicated watch edition.

Via +Don McArthur.