Tuesday, October 10, 2006

Evolution of Planets

I have not posted in a while, not because there is no news relevant to evolution, but because I have been in the middle of a career switch and rather busy.

Recent news reports have announced new and significant evidence for the hypothesis that planets form from dust that is scattered in space and gradually coalesces due to the mutual pull of gravity. The idea has been around a long time and I know of no reputable scientists who questions the idea. It is in perfect accord with both theory and observation. But science likes to confirm with more than plausibility. It likes to see evidence that definitively establishes a theory beyond any doubt.

For some time now, powerful new telescopes such as the Hubble Space Telescope have been detecting planets around stars. Telescopes have also detected stars with a disk of dust around them, something like our planet Saturn with its rings. The latest observations are of a planet and a disk around the same star and the planet is aligned with the disk.

What does this have to do with evolution? Evolution requires time. There is a wide range of evidence to suggest that our planet has been supporting life for several billion years, with the planet forming about 4.5 billion years ago, perhaps a billion years after the formation of the sun. This idea is also consistent with observations of other star systems, but now we have an observation that fills a small gap in this evidence.

It is also evidence that evolution, in a general sense, is a universal aspect of our universe. Science asserts that all stars form from clouds of dust and simple atoms and molecules that can be observed throughout our galaxy and others. When a critical amount of this matter forms, the forces of gravity overcome the forces holding the atoms apart and we begin to get nuclei fusing together and giving off energy, which accounts for starlight. It also keeps the star from collapsing further, as the energy given off pushes atoms apart on average as much as gravity pulls them together.

The earliest stars were probably made of just two elements, hydrogen and helium, the simplest of atoms. But when stars are really big, they burn through their nuclear potential and collapse some more and this leads to an explosions called a nova or a supernova. This fuses heavier atoms to form the heaviest of atoms so far observed. All this matter drifts out from the star, but globs of it can be drawn together again by gravity and a new system can form. Some of this heavy matter can form planets.

Some planets, such as earth, have the right amount of water and other chemicals to foster life. That life necessarily starts out simply, as complex self-replicating molecules. Over time, the process of natural selection begins to nurture evolution of these forms, and the process can lead to creatures such as ourselves.

So simple atoms evolve into heavier atoms which evolve into chemicals which evolve into life which evolve into self-conscious life, which evolve things like the Internet and blogs. Creationists and intelligent design exponents do not say much about the evolution of stars and planets. First it contradicts the idea that the universe is much older than indicated in Genesis. It also makes the idea of biological evolution all the more plausible.

Evolution happens. It is a wondrous thing. It is only a problem to those whose religion clings to the idea that human beings are extra-super-duper-special, the center of universe. But we don't have to be the center of the universe to be special or wondrous.


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