So far, I have discussed how the earth’s magnetic field, dendrochronology, the amount of sodium in the oceans, and the amount of helium in the atmosphere all indicate a very young earth. The last on my “top five” list is the nature of the thermonuclear fusion that powers the sun.
The sun is the earth’s main source of energy. Nearly all of the energy that powers life on this planet comes from the sun. In addition, the sun’s light and the characteristics of the earth’s atmosphere make our planet a perfect living oasis in the midst of an otherwise dead solar system. While most people know what I have written so far, you might not know that if the earth and sun were billions of years old, most likely the earth would have been simply too cold to support life throughout most of its history.
We know that the sun is powered by thermonuclear fusion. Light elements (mostly hydrogen) fuse together to become heavier elements (mostly helium). There are other reactions as well; two helium atoms in the sun can fuse to make beryllium, for example. What’s nice about these reactions is that they can be studied on earth in a nuclear chemistry lab. Thus, we understand quite a bit about them, even though they occur naturally only in stars.
One thing we know about these reactions is that they are affected by many things, including the surrounding temperature (if it is high enough) and the nature of the particles in the surroundings. Well…as hydrogen in the sun is converted to helium, the number of helium atoms in the surroundings increases, and the number of hydrogen atoms decrease. As we can tell from experiments on the ground, this will change the dynamics of the fusion of the hydrogen that is left. 1
Interestingly enough, the changes cause the remaining hydrogen to fuse more efficiently, which in the end, increases the temperature of the sun! Thus, unlike a fire that slowly dies out, a star like our sun actually gets hotter the longer time goes on2. This doesn’t go on forever, of course, but based on experiments done in the lab, it will go on for billions of more years if the sun is around that long.
So as long as thermonuclear fusion uses the same basic physics here on earth as it does in the sun, we can be pretty confident that the sun’s brightness is increasing over time. Well…if the sun really has been around for billions of years, we can use our knowledge of nuclear fusion to go backwards and see how bright (and therefore how hot) the sun was billions of years ago. Most evolutionists currently think life has been around for about 3.8 billion years. Back then, however, the sun would have been about 25% less bright than it is today (give or take a few percent). 3
So what? Well, if the sun were 25% less bright than it is today, the earth would simply be too cold to support life. In fact, it would be too cold to have liquid water present in any reasonable amount. This is a serious problem, however, because there is ample evidence that there has been significant amounts of liquid water on the earth during the earliest parts of its history. 4 So if the nuclear reactions in the sun play by the same rules as those in the lab, there shouldn’t have been liquid water on the earth billions of years ago. Nevertheless, there was.
Now, of course, if you are forced to believe in a billions-of-years-old earth because of your preconceptions, you can try to “wriggle out” of the obvious conclusions given by the data by making up stories. The current story in fashion is that there was a perfectly-coordinated change in earth’s atmosphere that offset the increase in the sun’s brightness. Billions of years ago, the story goes, earth’s atmosphere had lots more greenhouse gases, so the earth was warm despite the dimmer sun. Then, as the sun got brighter, there was a perfectly-coordinated dance in which the earth’s atmosphere lost greenhouse gases as the sun got brighter. Of course, there is no evidence for this, and it takes an enormous amount of faith to believe it could happen. Indeed, even the originators of the idea call it “speculative.”5 Nevertheless, when you HAVE to believe in an old earth, any way to ignore the data is a good way!
So if you have suffered through all six of the posts on this issue, you now know my philosophy and “top five” reasons for believing in a young earth. I don’t think the earth is young because Scripture says it is young – I don’t think Scripture necessarily says that. However, I do think that science is best understood in a young-earth framework. Sure…you can dream up scenarios to get away from the inconvenient facts provided by the five things I discussed in this series (as well as other things) that indicate a young earth. Nevertheless, the bulk of the scientific evidence points to a young earth, so you must ignore the bulk of the scientific evidence if you want to believe the earth is billions of years old.
Now don’t get me wrong. There IS evidence that the earth is billions of years old. However, the majority of it comes from processes that have not been studied long and are poorly understood. Thus, while the evidence does exist, I find it less reliable than evidence like what has been presented in this series. For now, then, I think the most reasonable scientific conclusion is that the earth is young, most likely on the order of 10,000 years old.
1. Gough, D.O., “Solar Interior Structure and Luminosity Variations, ” Solar Phys., 74, 21–34, 1981
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2. Jonathan I. Lunine., Earth: Evolution of a Habitable Word, Cambridge University Press, 1999, p. 38.
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3. Sagan, C. and Chyba, C., “The early faint Sun paradox: organic shielding of ultraviolet-labile greenhouse gases,” Science 276:1217–1221, 1997.
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4. Mojzsis SJ, Harrison TM, Pidgeon RT, “Oxygen-isotope evidence from ancient zircons for liquid water at the Earth’s surface 4,300 Myr ago,” Nature 409:178-181, 2001
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5. JCG Walker, PB Hays, JF Kasting, “A negative feedback mechanism for the long-term stabilization of the earth’s surface temperature,” J. Geophys. Res. 86:9776-9782, 1981
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