Science: Molecular Magic

I had a great deal of difficulty deciding what to post about today. So many discoveries have been made recently that it's impossible to keep up. But I decided, at last, that one of today's discoveries is representative of an incredible trend. Ever-finer techniques of molecular analysis are allowing scientists to determine things they never thought possible.

I mentioned in my previous post that scientists have found a way to effectively take a T-Rex's temperature. The idea is, each element's chemical properties are determined by the number of protons and electrons its atoms have. However, there is a third type of molecule that does not change the elements chemical properties and contributes only to its weight: the neutron. Heavy isotopes of an element are atoms that have more neutrons than usual, allowing scientists to distinguish them from "regular" isotopes by measuring their weight.

This used to be really, really hard to do. Decades ago, it was considered a revolution when scientists learned how to measure the amount of carbon-14 in a material, which allowed them to use carbon-14's decay rate figure out how old the object was within a few thousand years. These days, scientists are making such molecular measurements with precision and ease that we could once only dream of. These have led to some extremely impressive analytical techniques.

Our "paleothermometer" is one example of that. It works by a fine analysis of the distribution of heavy isotopes within the fossils. It turns out that, at lower body temperatures, heavy isotopes clump together more during bone formation, whereas at higher body temperatures, they're more spread out. It also turns out that we now have equipment sensitive enough to detect the difference made by only a few degrees' centigrade lifetime body temperature difference. This means we can effectively analyze a dinosaur's bones and tell what its body temperature was during its lifetime. When this technique is put into practice, we may finally know once and for all whether dinosaurs were cold-blooded like lizards, or warm-blooded like us.

For more information on the paleothermometer: http://news.yahoo.com/s/afp/20100524/sc_afp/ussciencepaleontology

This is by no means the only recent, impressive use of molecular analysis. Among those making interesting use of these fine analysis techniques are archeologists, anthropologists, and astrophysicists, and geophysicists.

Archeologists and anthropologists have been doing really impressive things by using differences in regional isotope distributions to determine where a metal was mined, or what kind of food a person ate. These techniques have revealed new things about trade routes during past wars by analyzing the isotopic ratios in the metal of recovered bullets. They have revealed the diets of peoples past, by analyzing the isotopic ratios in their bones. In a few cases, this has even led to surprises; one prominent figure in Chinese history was found to have a different isotopic ratio than expected, suggesting he was from a different region of the country than originally thought. Isotopic analysis, combined with our recently developed abilities to analyze minute amounts of DNA in immense detail, are allowing us to determine ancestral lineages and world history with a precision that was never imagined in decades past.

Geophysicists have been using isotopic analysis for years to determine the age and composition of rocks. Lately, however, still more techniques have become available, allowing them to measure things that were once thought to be immeasurable. Measuring the strength of the Earth's magnetic field in the past was once thought impossible, for example. But it has since been discovered that by analyzing the orientation of tiny magnetic crystals in rocks and even man-made ceramics, it is easy to tell how strong the Earth's magnetic field was, and even what its orientation was at the time the crystal was set. These types of analysis have shown that not only has the Earth's magnetic field reversed its orientation in the past, but it strength has declined by about 14% over the last 400 years. Despite the 2012 predictions, there's no need to panic about this fact; we are probably heading into another "flip" of the Earth's magnetic field, but these flips take thousands of years--they are not the overnight calamities that 2012 theorists portray them to be.

Last, and most interesting in my opinion, molecular and small-crystal analysis have contributed to scientists' understanding of the possibility of life on Mars. You may have heard of ALH84001, a meteorite from Mars discovered in Antarctica in the 1990s. This meteorite was a big deal because it contained something that looked a lot like fossilized bacteria from Mars. At first, scientists thought the meteorite may have been contaminated by bacteria after coming to Earth. This has still not been ruled out, but in recent years molecular analysis techniques have contributed some interesting insights into the question of Martian bacteria.

For one thing, tiny metal-containing crystals found in the meteor look more like byproducts of bacterial life than inorganically formed crystals we usually see on Earth. For another, complex organic molecules called "polycyclic aromatic hydrocarbons," also often associated with microbial life, have been found in the meteorite. The possibility still exists that the fossils seen in the meteorite are from Earth contamination, and that the crystals and hydrocarbons were formed by inorganic processes in deep space. But the presence of all three together is, in my mind, compelling. I think this is pretty good evidence that Mars had life, and perhaps even still does today.

For more information on the meteorite: http://nssdc.gsfc.nasa.gov/planetary/marslife.html

I've breezed over a lot of topics here to try to get the scope and magnitude of how important fine analysis techniques are, and how big a deal they are to modern science. If anybody has questions about a particular finding or method I've mentioned, please feel free to ask.