I used to think Santa was a myth

I know I said I’m on blogging break, but I still want to do my monthly repost thing.  This is a classic I wrote in 2011.

‘Tis the season for anecdotes…

I didn’t ever take Santa very seriously when I was younger. Or at least, not as far as I can recall. And I thought that no one else took Santa seriously either.

I mean, kids believing in Santa, that’s just something that happens in the movies, right? There are countless movies depicting little kids who believe in Santa Claus. They’ll write letters to Santa. They’ll wait excitedly at the stairs for Santa to come, deliver presents, and eat the cookies and milk. Kids believe in all these elaborate legends and rituals, sometimes even in the face of disbelief from their parents or older kids.

Of course, in these movies, Santa also happens to be real. But Santa isn’t real. So why should I think that belief in Santa be real? For me, belief in Santa was all part of the mythos, along with the elves, reindeer, and red suit. [Read more…]

Break notice

I’m going on a blogging break until 2017.  But I’ll still be around if you wanna chat in the comments.

Also, if you want to see more of what I’ve been writing lately, I have an ongoing series on The Asexual Agenda about tropes in ace webcomics.

Linkspam: December 11th, 2016

This month’s linkspam is predominantly about trans and gender issues. That might be a coincidence.

Prejudice, “Political Correctness,” and the Normalization of Donald Trump – Julia Serano has enough in here that she really could have written three essays, and then I would put it in my linkspam three times.  I particularly like the middle essay, where she talks about the uses of “political correctness”, and why activists think the word should be ditched even if it includes some genuinely objectionable activities.  I have said such things myself but could never say it so well.

Science isn’t Broken – In the past year or so, there have been many articles about the unreliability of science, and this is one.  I’m linking it just for the interactive toy that lets you try p-hacking.

I’m inclined to believe that science is doing just fine.  It’s journalists who have been too quick to trust an claim just because a study said so, and who are now surprised to find that studies are not so reliable as that.  Working scientists have always known to distrust studies’ conclusions.  This is true in physics too, being a “hard” science does not help.  In my field we don’t really calculate p-values, so p-hacking isn’t a thing, but we still have biases, just ones that are more difficult to characterize.

An epic battle between feminism and deep-seated misogyny is under way in South Korea – This is a pretty interesting read about the South Korean version of the culture wars.  It sounds like misogyny is really bad there.  The feminist organization Megalia is characterized as rather extreme, but in that context it might be warranted, I dunno.  This link was shared by a commenter. [Read more…]

Kochen-Specker Theorem explained

I previously explained Bell’s Theorem, which is a “no go” theorem of quantum mechanics. In brief, Bell’s Theorem proved in 1964 that any hidden variable interpretation of quantum mechanics must be nonlocal.

Of course, you may be thinking, maybe the world just is nonlocal, and that hidden information is being passed around faster than light. Unfortunately, there’s another major theorem which makes hidden variable theories even more unpalatable. In 1966-1967, the Kochen-Specker Theorem proved that any hidden variable interpretation must be contextual.

To understand the meaning of “contextual”, suppose we have a quantum cat, and the cat has many possible states. It could be awake or asleep. It could be happy or unhappy. Or the cat could be none of those things because it is dead. Now suppose there are two possible measurements, which answer the following questions:

(1) Is the cat awake, asleep, or dead?
(2) Is the cat happy, unhappy, or dead?

This is a quantum cat, so you can only choose one of the two measurements. However, even if you can’t make both measurements experimentally, you might reasonably expect that the outcomes of the two measurements are related to each other.  Specifically, if measurement (1) would find a dead cat, then so would measurement (2), and vice versa. This assumption is called non-contextuality. This cannot be true of hidden variable interpretations of quantum mechanics! Such theories must be contextual.

Figure 1: ambiguous catFig. 1: Cat of ambiguous state.  Credit: Visentico / Sento

[Read more…]

Bell’s Theorem explained

In 2009, I wrote an explanation of Bell’s Theorem that could be understood by popular audiences. I wanted to repost it, but ended up rewriting it completely.

Although the predictions of quantum theory are well-understood, its interpretation is famously difficult. Because quantum mechanics only makes probabilistic predictions, many people have desired a “hidden variable” interpretation, where quantum objects have definite states, despite appearances to the contrary. But hidden variable interpretations are generally not accepted.

It is certainly possible to create a hidden variable interpretation that agrees with the all the predictions of quantum theory, and de Broglie-Bohm theory is an example of such a interpretation. However, de Broglie-Bohm has a number of unsatisfying properties. Indeed there are a few theorems that prove that any hidden variable interpretation must have unsatisfying properties.

The most important of these is Bell’s Theorem, formulated in 1964. What follows is an explanation of the thought experiment, the mathematical proof, and its implications.

The setup

Bell’s Theorem considers a particular thought experiment, in which two electrons are emitted simultaneously from a single source in opposite directions. This source emits electrons that are “entangled”, meaning that their quantum states are correlated with one another. If you perform the same measurement on both electrons, both measurements will always produce the same result.1
[Read more…]

Origami: Square Star and other tesselations


Square Star, by Ekaterina Lukasheva.  The squares are on the side, not visible in this photo.  Ekaterina has her own fancier photos here.

The past month has been astonishingly productive, in terms of origami.  I discovered that there was a nearby origami convention so of course I had to go.  Most people were doing one-piece origami, so of course I ended up trying a lot of one-piece origami myself.

I was, however, pleased to see some modular origami representation, and in particular there was Ekaterina Lukasheva, of Kusudame.me.  She gave a presentation on the connection between modular origami and origami tessellations.  And afterwards, as a demonstration of principle, she showed people how to make the Square Star, shown above.

I think perhaps few people understood her talk, but as someone who is interested in the design of both modular origami and origami tessellations, I for one found it inspiring.  Further discussion and origami below the fold.

[Read more…]