Without a Grand Designer one of the major hurdles in believing in intelligent life elsewhere in the universe is, strangely enough, Evolution. Scientists believe the universe is between 10 to 20 billion years old. Then it took billions of years for planets to form around newly created stars. The Earth is estimated to be 4.6 billion years old. Scientists don’t know how quickly after Earth coalesced from primordial dust and gas did chemicals organize themselves into self-replicating, evolving systems. We do know the conditions for life was impossible during the Hadean Period (4.5 to 3.8 billion years ago) because Earth was being bombarded continuously by the remnants of asteroids, meteors and comets. As Earth began to take solid form, it had no free oxygen in its atmosphere. It was so hot that the water droplets in its atmosphere could not settle to form surface water or ice. The atmosphere was also so poisonous, comprised of high levels of ammonium, hydrogen, and methane, that nothing would have been able to survive. We can assume that other planets were experiencing similar conditions as ours because of the violable state of the universe at that time.
Evolutionists believe life formed during the Archean Period 3.8 to 2.5 billion years ago when the world’s landmasses formed. It was at the beginning of the Proterozoic Period, (2.5 billion years ago) that oxygen-forming photosynthesis began to occur. The earliest evidence for life on Earth comes from fossilized mats of cyanobacteria called Stromatolites in Australia that are about 3.4 billion years old. This only leaves 3.8 to 2.5 billion years for single cell organism to evolve into a multi-celled sentient being and doesn’t explain how life spontaneous began here in the first place.
The Rare Earth hypothesis states that for life to exist elsewhere in the universe it required certain conditions –
1) a galactic habitable zone.
2) a central star and planetary system,
3) a circumstellar habitable zone.
4) a right sized terrestrial planet.
5) the advantage of a gas giant guardian and large satellite.
6) conditions needed to assure the planet has a magnetosphere and plate tectonics.
7) the chemistry of the lithosphere, atmosphere, and oceans.
8) the role of “evolutionary pumps” such as massive glaciation and rare bolide impacts.
9) and whatever led to the still mysterious Cambrian explosion of animal phyla. The emergence of intelligent life may have required yet other rare events.
Earth only demonstrates how extremely rare life is in the universe. Our planet is currently nestled in a galactic habitable zone that represents less than 10 percent of the galaxy. Nearby supernovae have the potential to severely harm life on a planet with regular frequency. Such catastrophic outbursts have the potential to sterilize an entire region of a galaxy for billions of years. The galactic bulge, for example, experienced an initial wave of extremely rapid star formation, triggering a cascade of supernovae that for five billion years left that area almost completely unable to develop life. In addition to supernovae, gamma-ray bursts, excessive amounts of radiation, and gravitational perturbations affect the distribution of life within the galaxy. Earth has been spare these catastrophes by inhabiting a “goldilocks zone” far from the galactic center.
Numerous conditions make our home planet suitable for life. For starters,
1) it has liquid water.
2) an energy source and chemical building blocks like carbon, oxygen, hydrogen and nitrogen.
3) it boasts the right distribution of elements to ensure a hot metallic core and rocky mantle.
4) a large moon to help maintain climate stability by minimizing changes in planetary tilt.
5) an optimal distance from a stable star, which allows the continuous presence of liquid water.
6) the Earth’s electromagnetic field protects us from deadly solar radiation while Jupiter fends off most asteroids.
The Earth’s size and corresponding gravity holds a thin layer of mostly nitrogen and oxygen gases, only extending about 50 miles above the Earth’s surface. If Earth were smaller, an atmosphere would be impossible, like the planet Mercury. If Earth were larger, its atmosphere would contain free hydrogen, like Jupiter. Earth is the only known planet equipped with an atmosphere of the right mixture of gases to sustain plant, animal and human life.
The Earth is located the right distance from the sun. Consider the temperature swings we encounter, roughly -30 degrees to +120 degrees. If the Earth were any further away from the sun, we would all freeze. Any closer and we would burn up. Even a fractional variance in the Earth’s position to the sun would make life on Earth impossible. The Earth remains this perfect distance from the sun while it rotates around the sun at a speed of nearly 67,000 mph. It is also rotating on its axis, allowing the entire surface of the Earth to be properly warmed and cooled every day.
Our moon is the perfect size and distance from the Earth for its gravitational pull. The moon creates important ocean tides and movement so ocean waters do not stagnate, and yet our massive oceans are restrained from spilling over across the continents. If any of these conditions are absent, life as we know it wouldn’t exist.
“So? Where is everybody?” Google Fermi’s Paradox.
The possibility that life exists elsewhere in the universe is extremely improbable, if not impossible.