Tag: creationism

Entropy


It seems you can’t talk about entropy without mentioning the second law of thermodynamics. That law states that the total entropy of an isolated system can never decrease over time. This creates the asymmetry between the past and the future, the irreversibility of natural processes and the arrow of time. It is entropy that ensures that, on the macroscopic scale, time can only pass in one direction — from a state of lower entropy to one of higher entropy.

This is often simplified to define entropy as the increase in disorder with time. This is particularly favored by creationists who latch onto their own simplified version of the second law to convince themselves that evolution is impossible. Their version of the second law, usually stated something like, “Disorder increases over time,” assures them that a supernatural power is required to support life and evolution. Coupled with their mistaken belief that evolution is a force for directed improvement, this explains some of the crazy things they say.

Can you see where they went wrong in appealing to the second law? That’s right. They left out the part about where it applies to an isolated system. An open system, such as the Earth, can receive energy from an outside source, like the sun. Under those conditions the total entropy on Earth can certainly decrease, but only because the total entropy of the Earth-sun system is increasing as the sun dissipates its energy. Their other mistake is to misinterpret “can never decrease” as “always increases.” This whole process of misunderstanding and misinterpreting and misusing the second law is unironically a very good demonstration of entropy, which can never decrease in a closed mind.

The reason entropy is linked to thermodynamics is that it started out as a description of waste heat or energy loss in steam engines and other mechanical devices. Such things are never 100% efficient at turning energy into work, and the people working on the problem needed a term for their bookkeeping. It was only later as we understood more about the physics underlying thermodynamics that other definitions, such as “disorder,” evolved. It also applies to the dispersal of concentrated energy, and even the dispersal of particles.

Another way to define entropy is as the amount of energy (usually thermal energy) in a closed system that is unavailable to do work. You can have a lot of energy in a closed system — a boiler, for instance — but if the energy is evenly distributed throughout the system, then there’s no way you can get it to do work within the closed system. Therefore it has high entropy. The only way to get work out of it is to pair it up with an external system that is at a different energy level, and then tap into the energy that is transferred between them as they seek equilibrium.

Here is one more way to think of entropy. When a system is in a configuration that has few ways for its parts to be arranged, it has low entropy. A configuration that has many possible arrangements has high entropy. So a glass of water that has an ice cube in it has lower entropy than the glass of water after the ice cube has melted. In the first, all the coldest water is in the ice cube — fewer ways to do that, lower entropy. In the second, all the water is evenly distributed at the same temperature — more ways to do that, higher entropy.

So, entropy is inexorably increasing in the universe overall. It can decrease locally under the right conditions, but only at the expense of a greater increase elsewhere. It doesn’t prevent evolution, which actually depends on increasing entropy. It is entropy that tells us which way time flows — from low to high.

rjb

Evolution – Part Three

Photo by Michael D. Gumert. – CC-BY – No larger image available

Some years ago I published a series of articles about evolution in my local newspaper. It generated some interest and a spate of letters to the editor, and my publisher liked it. There was even a creationist who challenged me to a debate over it. I decided to reproduce it here. This is part three, which I called Walk This Way. See also Part One and Part Two.

The first primates show up in the fossil record about 50-55 million years ago. They are part of the resulting explosion of new species that evolved to fill environmental niches vacated by the non-avian dinosaurs, after they went extinct sixty-five million years ago. Many of the new species are mammals, and we see a mammal-dominated landscape right now. Of the mammals, it is the primates which interest us the most, as they are our ancestors. Primates spread out and evolved into many different species, including lemurs, monkeys and apes. They can be found in most parts of the world, but it was in Africa where the line led to humans.

Between seven and eight million years ago a primate living in Africa split into two species. Such splits normally result when two populations of one species get separated somehow. Something like that happened to the common ancestor of chimpanzees and humans. A fossil from that period shows definite signs of an upright, two-legged gait, but the oldest hominin fossil with extensive bipedal adaptations is Ardipithecus ramidus. That was the beginning of the hominin, or human-like primate. Since then it evolved and radiated out into many different hominin species, most of which have gone extinct.

The first evidence of stone tools shows up at least 2.6 million years ago, with some evidence that pre-homo hominins were using them as early as 3.3 million years ago. Undoubtedly they were using tools made of other materials like wood and grass, but only stone can survive long enough for us to find.

Homo erectus is thought to have tamed fire by about 1.8 million years ago. Others put the use of hearths beginning later, at about 800,000 and even only 300,000 years ago. Much of the discussion revolves around whether we were simply burning grasslands to improve hunting, or actually sitting around a hearth cooking food on a regular basis. Those favoring the earlier date cite the shrinking jaw and growing brain of H. erectus as evidence that they were cooking their food. The pinnacle of upright hominids seemed to have been reached, but their brains were only about half the size of ours. Larger than the brains of similar-sized animals, but still too small by our standards.

Increasing brain size was the next big step. By the time we reach the age of Neanderthals, about four hundred thousand years ago, and modern humans at about half that, our brains were as big as they are now.

Since then it’s been a matter of social and technological evolution. The first jewelry shows up about 75-100 thousand years ago. The first garments appear to have been manufactured about 100 thousand years earlier, based on the evolution of body lice. The tool set became extremely sophisticated.

Neanderthals died out about thirty thousand years ago, leaving only a single hominid species on Earth for the first time in millions of years. Our cultural evolution continued to accelerate, as evidenced by sophisticated cave paintings, bringing us to the present state of high civilization.

Let’s hope we’re not due for another mass extinction.

rjb

Evolution – Part One

Credit Steinhöfel-ESO - CC-BY

Credit Steinhöfel-ESO – CC-BY – Depicting the evolution of a main sequence star – tap for large image

Evolution: A gradual process in which something changes into a different and usually more complex or better form. The Free Dictionary, definition 1(a).

Some years ago I published a series of articles about evolution in my local newspaper. It generated some interest and a spate of letters to the editor, and my publisher liked it. There was even a creationist who challenged me to a debate over it. I decided to reproduce it here. This is part one, which I called Evolving in Spite of Us. See also Part Two and Part Three.

When we think of evolution we usually think of life. It seems natural to think of Darwin’s “origin of species” as being what evolution is all about. After all, that’s what people are usually talking about when they talk about evolution. It’s good to remember, though, that not only life evolves. Pretty well anything you can think of is changing over time. Everything is in the process of transforming from one state to another. Since that’s practically the definition of evolution, it’s safe to say that everything is evolving.

For example, the interior of our planet Earth is gradually cooling over the eons. That means that there is less heat energy to drive the movement of the crustal plates, and therefore continental drift will gradually slow down. Eventually, if given enough time, Earth would cool enough to set and the continents would never move again. Fewer earthquakes. Fewer volcanoes. Less mixing of the various parts of the biosphere. The Earth is evolving.

Our Sun is also evolving. It’s much hotter now than it was when it was young. It’s been slowly heating up in the four-and-a-half billion years since it was born. If it follows the course of other stars of similar mass and composition, and there’s no reason why it shouldn’t, in another four or five billion years it will be a red giant. This will likely happen before the Earth can cool down enough to set. By that time it will have burned Earth to a crisp, possibly even growing large enough to engulf it. Life on Earth has been adapting to the Sun’s increasing output, even to the point of actively adjusting the atmosphere to keep it in the right temperature range. Nothing is likely to compensate for being engulfed, though.

Even the universe as a whole is evolving. We can tell that it’s expanding, which implies that it used to be smaller. We know that the universe was different in the past, to the point where there were no galaxies or stars at all. In the past it was very small and very hot. After about 14 billion years of expansion it exists in a state which supports life. Unfortunately, the rate of expansion is increasing. If nothing happens to change things, the universe is going to grow increasingly cold and dark. Eventually it will no longer support life.

We may continually come back to life when we think of evolution, but evolution goes on regardless of life.

rjb

Creationism Invades Europe

I thought Europe was our bastion of rationality. Our mature cousin who could be counted on to buffer the immature enthusiasms we’re prone to on this side of the Atlantic. Now I’m not so sure. If this article is to be believed, our European cousins are just as susceptible as we are.

An antiscience movement once limited mostly to the U.S. is gaining ground on the eastern side of the Atlantic

It’s following the same path it took over here. Although forewarned, European journalists are apparently not forearmed. They’re falling for the same tricks over there as ours did over here. They frame it as a conflict between science and religion. They fall for the false dichotomy of evolution versus creation, lured by a nice, simple, easily-headlined conflict. And they accept the false premise of a balanced debate.

Some investigative journalists tried to make sense of what was happening and figure out who these creationists were. Most, they found, were just reiterating the old science versus religion theme—evolution against creation, with Darwin in one corner and God in the other, waiting to go the next round at the sound of the bell.

If it follows the path we followed over here, soon they’ll have their schools teaching creationism in science classes, so their students can get a “balanced” picture of the two “belief systems.” I’m sorry Europe. We should have tried harder to warn you. I guess we just didn’t think it could happen there.

Check out the article.

Source: Creationism Invades Europe – Scientific American

rjb

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