1. 2012
Apr
09

## Optimal strategy in quantum tic-tac-toe

Here’s something I discovered recently: quantum tic-tac-toe is a variant of tic-tac-toe which allows players to make multiple moves at once, in an attempt to simulate quantum entanglement and superposition. Apparently it was invented in part to provide a way of visualizing quantum concepts. In that respect, it seems to be a decent but imperfect conceptual aid, but it’s a pretty interesting game in its own right.

Anyway, tic-tac-toe is one of the simplest games there is, so the optimal sequence of plays have been known for a long time (in particular that if both players play optimally, the game always ends in a draw). But what about quantum tic-tac-toe? This question recently popped up on Board & Card Games Stack Exchange, and I’m rather curious to see what answers it comes up with. Currently it has a 100-point bounty attached, which means if you contribute the winning strategy, you could get 100 free reputation to get your start on Stack Exchange!

2. 2011
Nov
03

## How much does data weigh in flash memory?

An interesting article in the New York Times has been making the rounds of the internet lately. It talks about the tiny theoretical increase in weight of a Kindle when its memory is full as opposed to when it’s empty. Since I’ve previously written about the weight of data on a magnetic hard drive, I couldn’t resist taking a look at the equivalent effect for flash memory.

To begin with, we need to know a little about how flash memory works, and to do that, we need to know how transistors work. A transistor is just a tiny electrical switch. It has two contacts, the source and the drain, that are separated by a layer of material with an excess or lack of electrons. Normally this configuration blocks any current from flowing between the source and the drain. But when the right kind of voltage is applied to the separation layer, it removes the excess (or fills the lack) of electrons, allowing current to pass through. (For the record, I know I’m not doing justice to semiconductor physics here.)

As described in a pretty good article on Explain That Stuff!, and several other sources I’ve …