The Wireworld computer

Wireworld computed primes up to 31I’ve been interested in cellular automata for a very long time, dating back to when I was a kid. One of the first BASIC programs I remember writing was a version of Conway’s Life that would run on my Atari 400 computer (very slowly I might add). But I’ve also been intrigued by a very simple cellular automata called “wireworld”. Unlike Conway’s Life, each cell in wireworld can be in one of four states:

  1. insulator: cells in this state are always insulators
  2. electron head: heads always become tails in the next time step
  3. electron tails: electron tails always become copper in the next state
  4. copper: copper will remain copper unless there are precisely one or two heads adjacent to the cell, then it will become a head.

If you play with this, you might see why it would be called wireworld. I’ve known for sometime that you can create all kinds of logic gates with this automata as a basic technology, but today I found this very cool website which implements The Wireworld computer, a complete computer that computes primes, simulated in a Java applet. Very, very cool.

Addendum: I left the java applet running overnight on my machine at work. It computed primes up until 31, pictured at right (click on the image for a full resolution image of the computer state).

Flash Boil!

A couple of days ago I mentioned the idea of supercooled water existing in liquid form well below the freezing point. Perhaps more dangerous is another delayed phase transition: water can exist in liquid form at temperatures much higher than the boiling point and can flash boil when subject to a disturbance. This usually happens in the microwave oven, which is why sometimes people recommend placing a wooden skewer into a cup of water that you are heating for tea.

Check out the videos here for some examples. Do not try this at home: you can be badly burned by experiments like this. IIf you don’t particularly value your life, you could refer to Bill Beatty’s list of unwise microwave experiments for more dangerous ways to learn about science.

Paris By Night

Stumbleupon sent me to this incredible nighttime panorama of Paris taken somewhere near Notre Dame (you can see the big rosette window in one part), but includes views of the Seine, the Eiffel Tower, St. Eustace, St. Michelle, Sacre Couer in the distance, and the Louvre. Very nice. If you click here, you can see a slightly lower res version of the same panorama in a viewer that will allow you to scroll left and right.

Phil Plait v. Bart Sibrel

Some of you may remember hearing the story about Apollo astronaut Buzz Aldrin punching some lunatic who was trying to badger him into swearing on the Bible that he really did land on the moon. That was Bart Sibrel, and he’s gonna be on the radio today to sell his brand of bullflop on 97.1 FM St. Louis. Luckily for all, Bad Astronomy astronomer and blogger Phil Plait has also agreed to be on the show. It will be at 5:00 PM Central time Monday, Dec 12th, and can be heard via their streaming website. I’ll be tuned in!

Update: Sigh. Their website requires IE, so I guess I won’t be tuned in. Bummer.