The article, which does a nice job charting the history of strong beer, is intriguing--but the arms race less so. The road to a 43% beer involves a kind of distillation, not brewing. In brewing, alcohol is produced by yeast; it's actually yeast's excrement, a chemical byproduct of the conversion of sugars. At high enough levels, alcohol becomes toxic to yeast, so there's a natural ceiling for the amount of alcohol you can get through normal fermentation.
The process of making eisbock--which is what all these super-strong beers are--involves dropping a beer to a temperature below the freezing point of water but above the freezing point of alcohol. What results is a half-frozen cask. Remove the ice and you've taken just water, leaving more concentrated liquor behind. (Normal distillation involves heating liquid to separate compounds--but this violence would damage beer in a way freezing can't.) In order to get beer as strong as liquor, you have to refreeze a batch over and over again. Here's Georg Tscheuschner, the record-holding brewer at Schorschbräu:
“To create the 43% beer, I had to filter around 15 times”, said Tscheuschner. “I actually lost count, but I think it was 15 times. You end up with only 50 litres from the 800-1000 liters that you started with. You need to do a lot more filtering to get a beer from 32% to 43% alcohol because whereas in the first filtering (of the ice), you might add say 5 or six percent ABV, but towards the end of the filtering process, it's maybe even less than 1% additional ABV for each filter. Towards the end it becomes very difficult.”I don't have any problem with eisbocks, but their increasing popularity means we're hearing more and more about 80-proof "beers." These aren't beers. Scotch begins with an unhopped beer and goes through distillation; we call it whisky. When beer is subjected to freeze distillation and is transformed into a liquor of 43% alcohol, it's not beer anymore. Too bad the term "malt liquor" has already been used. Beer liquor? I don't know; just don't call them beers.