Last time we looked at how the area is just right - that is the laws of the universe allow life to exist. Today, I'd like to look more closely at the other two features that make life possible: our solar system is built for life and our planet itself is just right.
2. Our planet and solar system are poised for life (the cabin is built right)Going back to our cabin analogy, it's not merely that the area where the cabin is built is just right for you to survive—the cabin itself has to be made the right way with the right materials, otherwise it will do you no good at all. Imagine if the cabin had huge holes in the walls and ceiling. It would let the heat and the cold in and not sustain your life. Imagine also if the cabin was made out of paper or sand, which would quickly give way to the wild beasts outside or simple erosion. None of these situations would be of benefit to you when you needed it most.
Similar to the cabin, our little neighborhood in the universe, our solar system and the planet Earth, also show remarkable design for life. In their great book Rare Earth, scientists Peter D. Ward and Donald Brownlee note just how unlikely it is that another planet in the universe would have the perfect conditions for life that our planet Earth does. We live in a spiral galaxy, but not in a portion crowded with stars. Our sun sits far enough away from the center of the galaxy, yet in-between two of its more densely-packed arms, what Ward and Brownlee call the "Galactic Habitable Zone." 4 They note that the distance of our Earth from the sun is also perfect , not letting the oceans boil away (possibly like Venus) or freeze over permanently (like all water on Mars). 5
Our sun is also the right kind of star. Did you know that 95% of stars in the universe are smaller than our sun?6 Planets need to be closer to smaller stars in order to get enough warmth for life, but when planets do get closer, the star's gravity keeps one side of the planet constantly facing toward it, freezing out the atmosphere. If our sun were much smaller, it wouldn't put out enough heat, and if it were larger, it would be so hot that it would sterilize the planet of all life.7 And because our sun is not too red (which would also make it too cold for life) or too blue (which would burn too quickly to sustain life), we are able to exist.8Everything seems to be not too hot nor too cold, but just right for life to exist on this particular planet.
Lastly, the fact that we have the gas giant planets (Jupiter, Saturn, Uranus, and Neptune) at the outside of our solar systems allows life on earth to continue. According to Ward and Brownlee, these gas giants not only carried elements such as carbon, nitrogen and water to earth in the early stages of its formation, but they continue to provide an invaluable service of catching large asteroid-type bodies that would otherwise smash into earth and extinguish all life on the planet. 9
There are many other examples of how our solar system is perfectly fit for life, but these will do well for a start. This is why Ward and Brownlee write, "With the best of intentions, but limited by natural laws and materials, it is unlikely that Earth could ever truly be replicated. Too many processes in its formation involved sheer luck." 10 You can see why Paul Davies calls the Anthropic Principle, "the Goldilocks Principle." Just as Goldilocks found to porridge and the bed that suited her, we've stumbled onto a cabin that suits us perfectly.
3. The Earth is stocked for life (the cabin is properly equipped)We've talked about the area being right for our cabin and the cabin being built properly to sustain us, but both those things wouldn't do us much good if we had to ride out several months of winter in a cabin not stocked with all the things that keep us alive. So it is with the Earth. It's not enough that it be in the right place with the right laws in the universe; it also has to protect and provide the ongoing sustenance for any life that may be found here. But yet again, we find that the Earth is just right to allow mankind to not only live, but to thrive. For example, the fact that our planet is 70% water has a major impact on supporting life. If there were too much water, then no dry land would appear to allow advanced life. Too little water and the temperatures on Earth would vary too drastically for advanced life to thrive.
Whereas most substances have very predictable behaviors based on their molecular construction, water seems to be unique in how it violates these expectations. For example, changing from a liquid to a solid means that as the molecules of most substances slow down, they get closer together, making the material heavier in its solid state. However, water does just the opposite: just before it freezes, it expands, allowing ice to float on liquid water. If this didn't happen, then all of the Earth's bodies of water would eventually freeze from the bottom up. But instead of freezing, the ice provides a cover over the liquid water, helping to retain the liquid water and therefore also adding to its stabilization of the surface temperature of the Earth.
Beyond water, other factors make Earth just right for life. The gases that make up our atmosphere help regulate the Earth's temperature, keeping it even too. Too many gases and we'd over heat, but too few and life would die from the radiation penetrating the atmosphere from space.11 Astronomer Hugh Ross gives us an impressive list of dozens of such conditions for life to thrive on earth: If the oxygen-to-nitrogen ratio in our atmosphere were larger, advanced life functions would proceed too quickly; if it were smaller, advanced life functions would proceed too slowly. If the Earth's crust were thicker, too much oxygen would be transferred from the atmosphere to the crust; but if thinner, volcanic and tectonic activity would be too great. Water vapor levels in the atmosphere are just right; if greater, a runaway greenhouse effect would develop; but if less, rainfall would be too meager for advanced life on the land. 12
The fact that our Earth has a single, sizable moon also becomes crucial to our existence on the planet. In their book The Privileged Planet, Guillermo Gonzalez and Jay Richards write that the Moon serves to stabilize our planet's rotation, keeps the Earth's axis at the perfect tilt to allow consistent seasons, and — by raising the ocean's tides — it delivers nutrients stirred up from the ocean floor and delivers them on land while it simultaneously promotes ocean currents distributing heated water throughout the different oceans.13
Is it All Just a Coincidence?Perhaps someone desperate might hope to find a cabin in the wood, but to find it filled with the presence of your favorite food, stocked with insulin in the medicine cabinet, and containing all the clothing in your size is far beyond a stroke of luck, especially since these things are not contingent on each other. In finding so many of these "coincidences," it would be irrational to draw a conclusion that this was all chance. You may not be able to explain why it all works out, but it's obvious that whoever built this cabin had you in mind and did it on purpose. And scientists are finding more and more that the sheer number of "coincidences" in the universe of physical laws being just right for life is simply too much to dismiss. Paul Davies goes on to say:
"Certainly the existence of life as we know it… would be threatened by just the tiniest change in the strengths of the fundamental forces, for example. The laws that characterize our actual universe, as opposed to an infinite number of alternative possible universes, seem almost contrived — fine-tuned some commentators have claimed — so that life and consciousness may emerge. To quote Dyson again: it is almost as if 'the universe knew we were coming'."14Indeed, the mountain of such factors points to the fact that someone "rigged" the system. Perhaps some of these factors are found elsewhere in the universe — there are other spiral galaxies and yellow suns, though not plentiful, that do exist. However, I think that when taken together, this evidence implies much more than mere coincidences. Robin Collins quotes philosopher John Leslie correctly saying, "Clues heaped upon clues can constitute weighty evidence, despite doubts about each element in the pile."15 If the universe itself is put together correctly to support life, then we can't stop at the universe as an explanation for our existence. We have to go to something or Someone who existed before the universe, Who designed the universe with the purpose of creating it so humanity can live and thrive in it. The design of the universe argues for the existence of God.