Quantum Mechanic

Content from 2012-01

Maxwell's Sheep

posted on 2012-01-31 17:26:17

In the late 1700s, James Maxwell came up with a dilemma that, although just meant as a though experiment, was a troublesome idea to physicists.  He came up with a clever arrangement of systems of matter at different temperatures that might possibly violate the second law of thermodynamics, which would be troubling because, well, it's supposed to be a law, and we don't like nature going around breaking its own laws, since when that happens, it means we got the law wrong in the first place.

The experiment is as follows:

  1. We have two systems of different temperatures that are isolated from each other and any other system they could exchange heat with.  Since the energy has nowhere to go, they will remain at this state. (This is in accordance with the first law)
  2. We bring the two systems into contact and have a small door, guarded by a small demon, which only allows heat to flow one direction. That is, the demon checks if a particle moving from one system to the other is one of the 'hot' particles and allows it to move through in one direction on that condition.

Here we have to stop a minute and realize, as many did after him, that the situation where this demon requires no energy to do its census and rearranging of every molecule in the systems is impossible.  Measuring the particles requires interacting with them, and so the demon itself is part of the large system here and the energy it uses sorting is part of the overall equation.  This is where my experiment today is different!

I am performing this demonstration in Minecraft, which is a made up world that very clearly marches to the beat of a different Grand Unified Theory, and so I can create a zero-entropy demon.  My demon will be played by a fence gate and a pressure plate.

Fig. 1: Most of the sheep start out in section two.

Here we can see a set of two sheep pens with my wonderfully rainbow-colored sheep in them.  All but the red sheep are in pen two (the further pen) representing a system at higher energy than pen one (the nearer), where there is just one sheep.  In the Middle is the gate with a pressure plate which will cause the gate to open located on the side of higher energy (read: more sheep).  This means that energy (sheep) can only flow from the higher energy to the lower energy pen1. This may seem obvious, but it's also the situation Maxwell tried to set up in his famous experiment.

Let's see what happens!

Fig. 2: Here, we see some sheep have entered pen one, a short time after Fig. 1.
Fig. 3: All the sheep are in pen one.

Long story short, it worked! I left the sheep alone for a little while, as the time of day change demonstrates nicely, and when I returned they were all stuck in the near pen. In case it was in any doubt, this says some strange things about the state of entropy in Minecraft. Perhaps things like cheap cold fusion are easy in this world. Maybe I just need to wait for a hydrogen block and a deuterium block...

[1] I have chosen to ignore second-order sheep effects, like a sheep stepping on the plate and allowing another sheep from the lower energy side to pass back into the higher energy side.

The Same Man Who Helped Stop Europe From Starving Invented Gas Warfare

posted on 2012-01-20 16:59:54

Frtiz Haber was a German chemist who invented both a process for nitrogen fixation, which kept many people in Europe from starving, and pioneered the use of chlorine gas in trench warfare.

Brought to you by a Radiolab episode I listened to yesterday.

Baking bread

posted on 2012-01-17 17:27:10

Lately, I've gotten into the habit of baking my own bread. It always send a little odd going to the store and spending 3 or 4 dollars on something so simple, and I've always wanted to try it, so about a month ago, I gave it a shot.

image
Two loaves baked the same time at different temperatures.

I was surprised that I didn't need to do any substitutions, but I suppose that bread would be one of the first things people would figure out, even if it were a milk our eggs heavy recipe. I was inspired by Minecraft, which I am currently enthralled by.  I will probably have to write about that separately, but the important part was the pride I felt when I finally figured out how to craft bread to survive in the game.

Here's the recipe:

 Simple Wheat Bread




  • 1 packet active dry yeast

  • 2 1/2 cups warm water

  • 2 tablespoons olive oil

  • 1/4 cup sugar (or honey)

  • 2 cups whole wheat flour

  • 2 cups bread flour

  • 1 cup oats


    • 3/4 c. ground (in food processor)

    • 1/4 c. whole


  • 2 teaspoons salt

  • 3 tablespoons vital wheat gluten


  1. Combine the sugar, water and yeast in a small bowl, let them sit and do their thing for 10 minutes or so, and assemble the dry ingredients while you wait!
  2. Blend 3/4 of the cup of oats.
  3. Mix whole wheat flour, oil, gluten, 1 c. bread flour, all of the oats, and salt in a big bowl.
  4. Add the yeast to the dry ingredients and mix.  Add in the last cup of bread flour - the dough should be sticky but hold together.
  5. Let rise 1 hour.
  6. Punch down the dough, separate into two equal pieces, put into oiled bread pans, and allow to rise another hour.
  7. Bake in preheated oven for a half hour at 350 Fahrenheit for a light crust, 450 F for a dark crust.
  8. Remove loaves from bread pan and place on cooling rack.
  9. Wait for it...
  10. Enjoy bread.