Hawking Up Hairballs

Saturday, October 21, 2006

Weird Science

In the last twenty years or so, scientists have discovered microbes in a variety of odd places. For example, there are apparently bacteria that live on the deep thermal vents at the bottom of the ocean. These bacteria thrive in environments where the temperature is around 380 degrees Centigrade. Some of them are part of a larger group of organisms called lithotropic bacteria, also known as rock eaters, that use inorganic chemicals for food. These bacteria have been found deep below the earth’s surface. They have also been found in unexpected places on the surface itself. A variety of such bacteria is apparently eating the sandstone in the medieval cathedral in Cologne, Germany. However, the oddest microbe that I’ve ever heard of has got to be the species recently discovered in a gold mine some 2.8 kilometers under the ground in South Africa. These little bugs apparently depend on uranium for their existence. The radiation from the uranium breaks water up into its constituent hydrogen and oxygen, and the bacteria use the hydrogen as their source of energy. For those of you who would like more information, here’s a press release from Indiana University, strange microbe.

Such discoveries make it more likely that life, at least in its simplest forms, may be pervasive in the universe. Such speculation has also been bolstered by the discovery of amino acids in outer space. (Here’s a link about that, amino acids.) Amino acids are the building blocks of proteins, so some scientists have been led to speculate that life on earth was seeded by amino acids that fell to earth on meteorites and such.

Even more interesting about these amino acids is that they exhibit the same chirality as those in the proteins on earth. Let me explain. Many organic molecules exhibit chirality. Say you have a chain of carbon molecules with a couple of hydrogen atoms hanging off of it. They can be on the left or right side of the chain. (This is not a really scientifically correct, but it gives you the idea.) As it turns out, all of the amino acids involved in life are of the left-handed form. Interestingly enough, all of the sugars involved in life are of the right-handed form. The opposite varieties of amino acids and sugars are inactive, and can even be toxic. No one really knows why the chemistry of life exhibits this property. However, it is intriguing that the amino acids discovered in space are of the left-handed variety. Here’s a link for more on that, chirality.

This stuff is fascinating and, unless you’re a Bible freak or something of that sort, it makes sense that life is commonplace throughout the universe. It is mere hubris to believe that we on Earth are sui generis. Whether or not we’ll ever encounter other intelligent life is another matter altogether. The distances involved and the time it would take to travel them make it seem unlikely, but fifty years ago, you would have been counted as a crackpot had you suggested that rock-eating bacteria lived miles below the surface of the earth.


Blogger David Matthews said...

Fascinating stuff. Thanks for the nutshell account.

1:15 PM  

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