How to Build a Snowflake

Larry O'Hanlon, Discovery News Jan. 18, 2008 -

- Two mathematicians have for the first time created a computer simulation that generates realistic three-dimensional snowflakes -- although even they aren't sure how it works.

"We know surprisingly little about how ice crystals grow," said Caltech physicist Ken Libbrecht, who is considered a leading expert in snow crystal physics.

Figuring out some of the details could perhaps teach physicists a lot about how nature "self-assembles" complex structures -- a trick that nano-engineers have been trying to learn in recent years, he said.

Mathematicians Janko Gravner of the University of California at Davis and David Griffeath of the University of Wisconsin-Madison avoided the old approach of virtually building the snow crystals molecule-by-molecule.

Instead, they used virtual 3-D cells much larger than water molecules, which behave according to the same physics thought to control crystal growth.

"This is kind of an intermediate approach," said Gravner. He and Griffeath created their virtual cells -- called cellular automata -- to be one cubic micron in size.

At that scale the cells, about the size of a speck of dust, mimic the physics of water vapor and crystalline growth.

They then ran the model many times to see what happened when they tweaked with temperatures and vapor pressures. The result was a wide variety of snow crystals -- including the complicated and stunning six-sided star crystals. Each crystal took about 24 hours to build using a powerful desktop computer, Gravner said.

"Some forms are easier to get than others," Gravner told Discovery News. In this way the model seems to reflect the predominant crystals seen in nature, he said.

"I think it's a real big advance since nobody was able to do it before," said Libbrecth. "People have tried to get realistic snowflakes and it just didn't work."

Those previous attempts tended to succeed up to a certain point, after which the virtual crystals would go nuts, probably because of errors that built up in the computations and overpowered the simulation, Libbrecht told Discovery News.

"These guys were able to generate some structures that were very well-behaved," said Libbrecht.

Their success is all the more interesting, said Libbrecht, because the details of the physics Gravner and Griffeath programmed into their model are not quite in line with what he and some other physicists think are going on in snow crystal formation.

So either the physicists have been wrong, Libbrecht said, or there's something about the modeling approach that allows it to work despite the physics. Either way, it's a bit of a mystery.

The Cruise

Gawd... where do I start. I hate the beginning, it seems so predictable, but I guess it really is the best place. I started getting nervous about 2 hours before the flight. The flight that would end in L.A. and was sure to give me the best view of the ocean I have ever had... well it would have, except that I got so fkn motion sick on the plane that I couldn't even focus, let alone enjoy the ocean. I got off the plane (a very long two hour flight) just to get onto a bus, an even longer 45 minute drive. I was already pretty tore up but this just made it worse. When the bus ride finally ended and I saw the cruise ship, that was when it really hit me. I'm going to be on a 13 fkn story Titanic, not just one day but all fkn WEEK! But, then I thought, nah... cuz this bitch has been sailing the ocean for nine fkn years, if something was gonna happen, it would have done so by now. So, on we go. That first few steps was awesome, then I started feeling the boat rocking and the motion sickness came back. Now let me just say to those fuckers who said, "it's not the size of the boat, it's the motion of the ocean" You retards ought to be drugged with crack and sleeping pills at the same time then sent out on a raft to enjoy the ocean. Fuck you. It's all about the size of the fucking boat. I promise you this. When you drag your happy ass onto a 13 story boat, the size is ALL that matters. FKN WOW!!! Oh, here's a pic...

There is really something about being on a boat that size. I know, it's really hard to imagine, but picture this with me if you will... see those itty bitty life boats toward the upper decks? Each one of those holds 150 people. Those fuckers are huge! And they look so tiny in comparison. Getting on and off was like walking into a sky-scraper that's a half mile long! I swear by the time you get from one end of this ship to the other you could have walked a full mile.
The ship was so lavish inside that it was like walking into a five star hotel. The staff was so nice and everyone treats you like a king.
The first several hours on the ship were just to acquaint ourselves with the area because it was like entering a new town. We did little other than eat the first night we were there. We got to watch the ship leave the port and we watched as the coastline disappeared into the sunset. If it gets more romantic than that, I'll have to see it to believe it.
Day two, Catalina... What a place! I don't think I'll ever go there again on purpose, but it was well worth visiting once. It was really kewl to rent a golf cart and just cruise around the island. That was a ton of fun and we saw a bunch of other things in the process. Such as the awesome view that you can only get from an island mountain. When you're surrounded by trees and a deep valley and off in the distance you can only see the sea, there is an awesome feeling derived from that. One of the things I noticed was that the sand was incredible there. It's not hard and packed like Idaho sand, it's warm and soft and perfect for beach volleyball or whatever you're into. We also saw some of the kewlest golf carts and some cars that looked like golf carts (like the mini). The shops were fun, but very pricey. Even still we had to buy some things to remember it with. And of course, we took lots of pictures.
Back on the ship that night for an evening of fine dining and entertainment. They hired a comedian who did a show, it was funny. I really get a kick out of watching a live comedian. It's the whole experience. What a blast. They also had a show with Vegas style dancers with stunning choreography and lots of lights and things that sparkle. It was fun to watch. I again, ate way too much this day as well. And I'm sure the room service at 1am right before bed didn't help anything either.
Day three. Not much different than day too... other than the place we were was much more of a shit hole. It looked like the run down parts of Idaho Falls. HA! Dirt roads and all! What a shit hole! I heard from a smart man and I finally understand what he meant when he said "The difference between L.A. and Mexico is that there are more Mexicans in L.A." He's right. We rented a car the size of a Tuna can and proceeded to putt around Mexico like a couple of tourists. It was awesome! We happened upon a shop selling marble chess sets, and had to have one! They are so kewl! And of course we bought more souvenirs than we really needed.
Day 4 was our day at sea. I've never eaten so much in my whole life! I ate enough to feed a third world country for weeks! We went to an art auction and saw another live show from a different comedian. This was the day we watched the dolphins swim beside the ship... well they could have been whales, cuz from 13 stories up it's hard to tell how big they really were. Everything looks tiny from that high! By this time in the trip I was on so much Dramamine that I couldn't have gotten motion sick from anything!
Day 5 was our return trip home and due to the Dramamine it was much better than the first flight. We spent forever in the airport waiting but finally got back to high ground.
The next day I was at Walmart and the cashier asked me how I was... come on, considering yesterday I was on a cruise ship, today fucking sucks!

Here are most of the pics from the honeymoon. Hope you enjoy (I don't really care if you don't, but I hope you do)