January 13, 2012

The Rare Earth Hypothesis Works Best with an Old Earth

As someone who believes in an old earth and the idea that God made the earth using billions of years of natural processes, I believe that the earth is rare in the universe and that scientific research will show that to be true, not just by checking for earth-like planets but more importantly by using models of planet formation and determining the requirements for a very long existence of life on the planet. God chose the right planet that could support life for some 3-1/2 billion years. This planet we live on is the most suitable for intelligent life, and science is beginning to point towards that truth. It’s been called the Rare Earth hypothesis.

Strangely, young-earth creationists have jumped on this Rare Earth bandwagon. I say strangely because they seem to end up using some arguments that only work for an old earth. My contention is that much of the evidence that earth is rare strongly indicates that the earth is truly old. Young-earth creationists are actually undermining their own beliefs by trying to use these arguments.

Here’s one example: the Galactic Habitable Zone. The idea is that there is a relatively small range of distances from the center of the galaxy that are good places for life to exist. If you go too close to the center of the galaxy, the neighborhood of surrounding stars is denser and the probability of a nova destroying life over a long period of time (say a billion years) becomes quite high. For that reason and other reasons, the earth’s solar system is considered to be situated at a good distance from the center of the Milky Way Galaxy. But, notice that this Galactic Habitable Zone is determined based upon the probability of novas over long periods of time. For a young earth, this Galactic Habitable Zone would become much, much wider. In fact, there is a good chance that the earth could have been almost in the center of the galaxy if it only needed to support life for 7000 years. Thus, using the Galactic Habitable Zone to support the idea that the earth is rare is to imply that the earth is really old.

Much of the evidence that says the earth is rare in the universe is based upon the belief that the earth needed to support life for billions of years. Yet somehow young-earth creationists think that they can steal these evidences for themselves. Not so fast. What some of them fail to understand is that if the earth is really so young, then scientists should be finding so many reasons why the earth itself could not support life for billions of years. Instead, scientists are finding (not at all by choice or bias, by the way) just the opposite: the earth was and is uniquely qualified to protect life from extinction for billions of years based upon numerous situational factors. This confounds scientists that don’t believe in the Bible, since they think that earth should be a relatively common planet in a common solar system.

Now, let me preemptively answer the rebuttal that young-earth creationists would probably make. They may say, “But God made the earth originally to be habitable for billions of years, just as if the Fall of Adam would never happen.” In other words, why should we think that God wouldn’t have made the earth to be uniquely protected and well-situated in the universe, given that He made it perfect to begin with?

The problem with this rebuttal is that it is clear that our solar system has significant problems and earth is subject to many kinds of catastrophes over long periods of time. However, those catastrophes are much less severe or likely in our well-designed galactic neighborhood and solar system. If God were intending to make a perfect system to support human life for billions of years, then it looks like He did a poor job of that, since there are asteroids that routinely strike earth, novas of surrounding stars that will likely jeopardize life on earth in the next few million years, and many other potential threats. Either God made our solar system better than other places but still not perfect—which is what the evidence is showing—or else He made it a perfect place. You can’t have it both ways.

Or can you? Maybe He made it a perfect place at first but then let it start to “fall apart” and decay after the Fall of Adam? This would be a nice attempt at trying to explain the evidence, but it misses the critical point. Even with things decaying, our place in the universe and the specific setup of the earth is so good that it should be able to support life for hundreds of millions of years, still. Why would God set everything up so precisely in a fallen world such as to make a place for life to exist safely for hundreds of millions of years, when it would only need to exist for about 7000 years? For instance, there is no good reason why God would not have made a star nearby that was ready to go supernova and destroy life on earth in the next 10,000 years, since He will make a new heaven and earth long before that time. (If there was no decay before the Fall, then it wouldn’t matter if such a star existed, because it would never go supernova in such a hypothesized world.) Clearly, even in our fallen world, even with decay and disasters, God precisely designed the earth and the solar system and galaxy to be able support life for much longer than 7000 year—barring an unlikely extinction event. Why would He make it so good even after the Fall? It would be a very unnecessary fine-tuning of everything.

But there’s another reason why the evidence supports an old earth. According to geologists, astrophysicists, and so on, over the last 4.5 billion years the earth has been carefully shaped to support life. There were many fortuitous events that allowed for life to flourish. If the earth is actually only 6000 years old, then all these ideas about how the solar system, the earth, and the moon formed are wrong. There then should be no reason why the models of formation would indicate a rare earth—but they do, or at least the evidence is mounting in that direction. The evidence that earth is rare does not just apply to its current state, but also its long history of existence over 4.5 billion years.

Plate tectonics is a good topic to investigate to show this point. If the plates of the earth did not move around, because of convection within the mantle, then our continents would not exist. Without larger landmasses the food chain would not function properly. For plate tectonics to work for billions of years, the earth had to have the right internal attributes. Most planets are not likely to have these necessary attributes, making earth rare. Young-earth creationists cannot condone such arguments, since they require an old-earth perspective. Also, young-earth proponents cannot attribute earth’s well-designed plate tectonics to God making the earth able to support life for millions of years, since plate tectonics has little or nothing to do with the future survival of life; it would seem to only be necessary in the past. Also, volcanism has been used to form land. Without volcanism it is probable that earth would have no continental land. The conditions necessary to form land has been perfect on earth, but other planets are not likely to have these same perfect conditions. This makes for a good rare earth argument. However, this argument presumes an old earth, once again. A young-earth creationist cannot embrace this rare-earth argument, either, since volcanism is considered harmful and the result of the Curse, and they do not believe the earth formed in the way most scientists do. Volcanism has no benefit for the future survival of life—at least not considered by itself.

From what I can tell, there are countless other examples that would support the idea that—given an old universe—the earth, the solar system, and the Milky Way Galaxy must be truly special in the universe. Many of these examples only work if you embrace Big Bang cosmology, planet formation models, and an old earth with all the supporting theories of how it formed. Young-earth creationists are trying vainly to utilize these kinds of claims that earth is rare, much to the undermining of their own beliefs of how the universe and earth were created in six twenty-four hour days. Unless they want to switch to old-earth creationism, they need to choose their arguments carefully.

In conclusion, the evidence is showing that the earth was formed through a very long process that was carefully designed to support life for billions of years. An old earth and universe actually lead directly to the conclusion that earth has been especially suitable for life for long ages, and that the likelihood of finding another “earth” in the universe is remote. Only if you embrace mainstream science can you rightly claim all the evidence for the rarity of earth, however. Young-earth creationists are inconsistent and illogical to adopt most of these rare-earth arguments. Given a universe that is about 13.7 billion years old and an earth that is about 4.5 billion years old, the evidence overwhelmingly indicates that earth has been one of the best places (and probably the best place) in the universe for life to thrive for over 3 billion years. Old-earth creationists make best sense of all this data.

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