Is Life on Earth a Random Accident?
When I became a high school physics teacher, I discovered that the standard curriculum left out what I considered some of the most fascinating aspects of physics: relativity theory, quantum mechanics, string theory and the multiverse. So, I added these subjects, and my students began to ask questions. One of the most interesting was why our planet was so friendly to human life. Was a creator involved? Or was it just a series of coincidences? Let’s take a look at what had to happen.
The Strength of Gravity
The Earth’s size and mass creates a surface gravity that is just right for humans. If we jumped, a weaker force of gravity would cause us to fly off the surface of the earth. Remember those videos of astronauts walking and jumping on the moon, which has 1/6th of our gravity? By contrast, too strong a force of gravity would keep us stuck to the ground.
The acceleration of gravity on the Earth’s surface is optimum for human life. It keeps our atmosphere close to the surface so plants and animals can utilize its oxygen and nitrogen. It lets you hit a golf ball a few hundred yards, enables planes to fly and parachutes to work. And you don’t need elephant-sized muscles to get up walk around.
The Goldilocks Zone
Our sun is a “yellow dwarf” star. Such stars generally last for 10 billion years and have a surface temperature between 5,300 and 6,000 K. We orbit the sun at a radius of 93 million miles, just the right distance to capture enough solar energy to keep the oceans liquid and the atmosphere healthy. Except at the poles, the Earth’s surface temperature enables human life to thrive.
The Earth is a Magnet
We are fortunate that our planet has a magnetic field. It is caused by the rotation of molten iron and nickel at its core. The Earth’s magnetic field stretches out into space from the north and south pole and deflects the stream of dangerous charged particles — the solar wind — which the sun constantly emits. The interaction of the Earth’s magnetic field and the solar wind also creates the northern and southern lights. If the earth’s magnetic field were to vanish, every living thing on the surface of the earth would be damaged or killed by the Sun’s radiation.
Our Helpful Moon
Most of the planets in our solar system have one or more moons. How does our moon help us? The gravitational attraction between the Earth and the moon stabilizes the rotation of both bodies, preventing the Earth from rolling at random in all directions. It also keeps the Earth from wobbling. That’s why we have a reliable cycle of day and night. No surface life would ever have developed had the earth been randomly spinning and rolling.
The Earth’s Axis is Tilted
Our planet is tilted at the perfect angle, 23.5 degrees, to create the seasons as we orbit the sun. The tilt angle determines which parts of the Earth get more sunlight as the year progresses. This is the primary cause of the intensity of the seasons for higher latitudes. Do you love Christmas and the Fourth of July? Thank the tilt of the Earth.
Our Well-Designed Constants of Nature
Dozens of constants determine the behavior of our universe. The gravitational constant, the electromagnetic constant, the velocity of light, the Hubble constant, the amount of dark energy and Plank’s constant are just a few. The masses of the elementary particles make up another set of constants. The values of many of these are known to an accuracy of more than a dozen decimal places. Now imagine the constants arranged on a board with a dial for changing each one. Physicists estimate that if you turned the dial for any of these constants, even by an infinitesimal amount, the universe as we know it would disappear.
Why Did it All Happen?
Theologians have an explanation for our cosmic situation: In the beginning, God created our universe and set the dials to the right number for each constant, thus making our world and its life forms possible.
Astrophysicists, on the other hand, continue to search for a science-based explanation for all of these fortunate “coincidences.”
