This is the third in a series of guest blogs on science, religion, and design by Dr. Ben Clausen of the Geoscience Research Institute, based near the campus of Loma Linda University. The words that follow are his.

This Earth has a unique set of conditions necessary for life. According to Ward and Brownlee (2000) in their book, Rare Earth, planets with conditions necessary for life are rare in the universe.   However, the on-going search for planets similar to Earth that could support life and for other intelligent beings (SETI) is engendered by the belief that although Earth is rare, it is not impossible to have such conditions elsewhere in the universe (Kasting 2010; Elkins-Tanton 2013).

Here are several examples of Earth’s unique features that make life possible: It rotates fast enough on its axis to give an equitable climate over much of Earth, but not so fast as to give a merry-go-round effect; The force of gravity on a much larger planet would be too great for humans to withstand its force but a smaller Earth with less gravitational attraction would not hold the atmosphere from escape; The molten nature of the interior of Earth creates a magnetic field that shields radiation from space; Earth has an abundance of the correct elements for life (carbon, hydrogen, oxygen, nitrogen, phosphorous), has the necessary atmosphere (nitrogen, oxygen, carbon dioxide, ozone), and has abundant water.

Another frequently mentioned design feature of Earth is the need for plate tectonics to sustain life. A planet with moving plates makes possible the formation of continents and the recycling and concentrating of the elements and nutrients necessary for life at the surface of Earth by the processes of volcanism, erosion, and subduction.

The unique properties of light in behaving both as a wave and a particle are important for life. Light can be reflected from a mirror and refracted, or bent, as it passes through a pair of glasses or a microscope lens. Light displays interference patterns as seen in the colors of a peacock wing or the hologram on a credit card. Some of the light spectrum is visible as red, orange, yellow, green, blue, and violet, but most light frequencies are greater or smaller than those in the rainbow, just as most sound frequencies are smaller or greater than those from a piano. Beyond violet are sunburn-causing ultraviolet and the even more energetic X-rays. Below red is infrared felt as heat, microwaves used in ovens, and radio and TV waves. Light behaves as a particle of energy when it hits a solar panel, or in photosynthesis. It has mass and is bent in strong gravitational fields. It sets the speed limit for the universe, 300,000 kilometers/second. According to special relativity, this speed is a constant and everything else is relative. This high speed is the “c” in Einstein’s famous equation, E=mc². When the mass “m” of even a very small atom is multiplied twice by the speed of light, it results in a very large amount of energy.

Earth’s fluid covering of air and water make life possible. The 20% oxygen and 80% nitrogen of Earth’s atmosphere are ideal. More oxygen would make fire control difficult, whereas less oxygen would be insufficient for life. Ozone, made up of three oxygen atoms, shields Earth from radiation coming from space. Air is “strong” enough to support an airplane and “heavy” enough to exert hundreds of pounds of pressure on our body surface. Water covers 70% of the planet. Its high heat capacity decreases Earth’s temperature fluctuations to a range acceptable for life. Unlike most substances, water expands on freezing; thus ice has a lower density than water and will float. If this were not the case, ocean basins would fill with ice from the bottom up. Water is as important for chemistry as light is for physics. It is a basic ingredient in biochemical reactions in our bodies, which are more than half water.

In 1913 Lawrence Henderson, a professor of biological chemistry at Harvard University, wrote The Fitness of the Environment, providing numerous examples of design from chemistry. A number of properties of water are essential to life: specific heat, freezing point, latent heat of fusion, latent heat of vaporization, thermal conductivity, expansion before freezing, solvent power, dielectric constant, ionizing power, surface tension. The chemical properties of carbon, hydrogen, and oxygen are also essential to life: number, variety, and complexity of compounds, number, variety, and complexity of reactions, evenness and lack of energy change of the process of hydrolytic cleavage, chemical relationship of carbonic acid and water to the sugars, instability of the sugars, variety and reactions of the sugars, and on and on.

Our solar system is uniquely able to sustain life. The distance to the moon is ideal to provide tides that keep the oceans from stagnating, but not so large as to inundate the land areas. Earth’s orbit is nearly circular giving a constant distance to the sun and constant heating for Earth. The sun is the right distance from Earth to provide the necessary light, but not too much heat. Thus water can exist in abundance as liquid, as well as ice and vapor. The other giant planets are far enough away to not disturb Earth’s orbit, but yet close enough to protect Earth from life-extinguishing extra-terrestrial impacts. The solar system is in the ideal location in the galaxy: closer to the edge of the Milky Way galaxy stars have too few metals and closer to the center extreme energy processes occur.

To be continued. . .