Snowball Earth

It's Science Saturday again!

This is actually a very controversial topic in geology circles. (In fact, I know a lovely lady off the coast of Tasmania right now digging for these carbonate structures at the bottom of the ocean floor.) This article relates to a controversial theory called the Snowball Earth theory for global climate from millions of years ago. (Sorry, I'm not talking about controversial modern day global warming today...) This theory assumes that the earth's climate is always in a delicate equilibrium. (This is a reasonable claim seeing that entire polar ice caps can melt in the period of a hundred years when the average global temperature only changes by less than 2 degrees farenheit).

Assuming you don't embrace the history of the friendly (but moronic) folks at Conservapedia, a lot of scientific research has been done to estimate the earth's climate dating back many many millions of years. Earth's temperatures are found through isotope studies of calcium carbonates (fossils).

Now, a brief chemistry class:
All materials on earth are molecules made up of atoms, including you and me and fossils. Crudely speaking, atoms in a molecules behave like balls strung together on networks of springs. These atoms (balls) stay attached in their networks of springs (chemical bonds) to form big nets of balls and springs (molecules).

Quantum mechanics tells us that these balls are always bouncing and vibrating slightly in their springs; they are never completely at rest (as opposed to classical mechanics, the physical laws that govern the world we live in, which says all objects will eventually stop moving once it comes to rest). When temperatures increase, the heat of the environment turns into energy, and that extra energy makes the balls bounce and vibrate more vigorously (just like heating a pot of water eventually makes water boil). However, these balls always stay attached to their springs until something hits the balls with so much force that a spring breaks (like cracking something when it gets smacked), or until the balls absorb so much energy that the vibrations alone break a spring (like when something melts). Lets ignore the smacking aspect and only think about temperatures.

When temperatures are hot, the energy from heat causes balls to bounce in their springs because energy makes balls bounce. When temperatures are cold, the balls only bounce in their springs minimally, because a lack of energy means balls can't bounce. HEAVY balls (even if they are the same size) bounce less than LIGHT balls, because more energy is needed to make heavy balls bounce compared to light balls. Thus, clusters of heavy balls bounce very little compared to clusters of light balls. It turns out that heavy balls are quite rare, but they appear in molecules at very predictable rates. For instance, if I had 100 of a particular kind of light balls, nature tells me that I can safely guess that 1 or 2 of those 100 are heavy, but not any more or any less. Furthermore, these heavy balls have special characteristics that allow us to seem them easily. These heavy balls are called isotopes.

Knowing this, hot babes like my friend can figure out how cold or how warm regions of the earth were as far as millions of years ago. They simply collect old fossils from different parts of the world and then figure out how old the fossils are through radioactive dating methods. By analyzing the atoms in the fossils (the balls in the networks of springs), they look for all the heavy atoms (isotopes) in the fossil. Once found, they look at where the heavy atoms are with respect to each other. If a lot of isotopes are found very close to each other, it means nature at that time must have been cold. This is because having heavy atoms together means nature at that time wanted minimally bouncing balls, and that happens when there wasn't much heat making balls bounce. If the isotopes are all far away from each other, then the temperature must have been warm, because nature at the time could afford to spread out the heavy balls making all the molecules overall more bouncy. Therefore, we can estimate temperatures of the planet.

How cool is that?