Taken for granted -- Take 3: Atmosphere

The earth’s atmosphere is a miracle. Considering that the earth atmosphere formed through a combination of volcanic activity and releases of gases from the mantle over billions of years and while moving at over 60,000 miles per hour around the sun and rotating at over 1000 miles per hour at the equator around its axis. Imagine the perfect balance of centrifugal (speed trying to force gas out of the atmosphere) and centripetal forces (like gravity keeping the gases in the atmosphere) for billions of years. The atmosphere has evolved from one of high hydrogen and helium to one today with 78% nitrogen, 21% oxygen, and several other gases like carbon dioxide, argon and neon.

Of all the planets we have discovered, none has an atmosphere conducive to life. Our most advanced instruments are primitive by the standards of the immense universe. By 2021, we had discovered about 4000 planets external to our solar system. It is estimated that our Milky Way galaxy alone contains hundreds of billions of planets. This excludes the planets in the estimated two trillion galaxies in our observable universe.

Earth's atmosphere provides several critical conditions that sustain life:

• it filters harmful solar radiation;

• regulates temperature;

• provides air for breathing, and;

• retains water through the hydrological cycle.

The earth's atmosphere filters harmful solar radiation

The main mechanisms are as follows:

Absorption: The ozone layer in the stratosphere absorbs a large amount of ultraviolet (UV) radiation, preventing it from reaching the surface. Ozone molecules absorb UV radiation, breaking down and reforming continuously.

Scattering: Short-wavelength radiation, such as ultraviolet and X-rays, is scattered in all directions by the air molecules in the atmosphere. This reduces the amount of harmful radiation that reaches the surface.

Reflection: Some of the incoming radiation is reflected back into space by the clouds, reducing the amount that reaches the surface.

If the Earth's atmosphere did not filter harmful radiation, it would be difficult for life to exist on the planet. The Sun emits a range of harmful radiation, including ultraviolet (UV) radiation, X-rays, and gamma rays. This radiation can cause damage to living cells, including DNA, leading to mutations and potentially cancer.

In conclusion, the Earth's atmosphere plays a critical role in protecting life on the planet by filtering harmful radiation. The presence of the atmosphere and its filtering mechanisms are essential for life to exist on Earth.

The earth’s atmosphere regulates temperature

If the Earth did not have an atmosphere, its average temperature would be much colder than it is now. Based on its distance from the sun, the average temperature of the Earth's surface without an atmosphere is estimated to be around -18°C (-0.4°F). With our atmosphere, the average temperature of the Earth's surface is approximately 14°C (57.2°F) because the atmosphere helps trap heat from the sun, keeping the planet warm. Without the atmosphere, the heat from the sun would escape into space, leading to much colder temperatures on the surface.

In conclusion, the Earth's atmosphere plays a critical role in regulating temperature by a combination of insulation, greenhouse gases, clouds, wind, and the water cycle. These mechanisms work together to create a stable temperature that is suitable for life on Earth.

The earth’s atmosphere provides air for breathing

The Earth's atmosphere is composed mainly of nitrogen (78%) and oxygen (21%), along with smaller amounts of other gases like argon, carbon dioxide, and neon. The exact mechanisms of how the Earth's atmosphere became mostly nitrogen are still being studied and debated by scientists --the most likely explanation is a combination of volcanic outgassing, meteorite impacts, and biological processes.

Nitrogen is an inert gas in our bodies as we breathe; however, it is critical for plants and trees. If there was no nitrogen, there would be no chlorophyll, no photosynthesis to produce oxygen, no green leaves, no green grass, and a dying planet.

Fortunately, we have a beautiful green planet which combines sunlight and carbon dioxide in photosynthesis to produce oxygen. Enough to have oxygen concentrations build up to 21% of the atmosphere over billions of years from less than 1% level after its formation.

For plant or human life to exist, oxygen is required. Human and animal life respire 24 hours a day, while plant life only respires during the night, otherwise they all die. The only natural process to produce sufficient oxygen for life to exist, is photosynthesis by plants or algae. The mix of nitrogen (78%) and oxygen (21%) is also an extremely low probability, but extremely fortunate. Most research suggests that the maximum concentration of oxygen that life can tolerate is around 35-40% oxygen. Beyond this level, the high concentration of oxygen can become toxic to most living organisms, leading to oxidative damage and potentially causing death. In addition, If you think forest fires are a problem today, a forest fire where oxygen exceeds 40% would be explosive.

At the same time, too little oxygen can also be harmful to life. Most terrestrial organisms require at least 5-10% oxygen to survive, and some organisms, such as humans, require much higher levels of oxygen to survive. The current atmospheric concentration of oxygen on Earth (21%) is perfectly suitable for most forms of life to exist.

Free oxygen in the universe is extremely rare. Oxygen combines with many other elements because it is highly reactive and has a strong tendency to form bonds with other elements. This is due to the presence of two unpaired electrons in its outermost energy level, which makes oxygen highly electronegative and attracts electrons from other elements.

Oxygen has a large electronegativity difference with many other elements, which makes it highly reactive and prone to forming chemical bonds. For example, oxygen readily reacts with hydrogen to form water (H2O), with carbon to form carbon dioxide (CO2), and with nitrogen to form nitrates, with silica to form quartz. Therefore, free oxygen in an atmosphere is extremely rare.

In fact, as of today, we have not discovered any free oxygen on any solid planet with an atmosphere in our observable universe. The only way free oxygen can exist based on what we know today, is that photosynthesis created it from carbon dioxide. Plant life precedes free oxygen. In our universe, we are indeed fortunate.

The earth’s atmosphere retains water through the hydrological cycle

The hydrological cycle is critical to life on Earth because it helps to regulate the planet's temperature at an average of 57 degrees Fahrenheit, distribute water and nutrients, and support the growth of plants and animals.

Water evaporates from the surface of the Earth into the atmosphere, where it forms clouds and eventually falls back to the ground as precipitation. This process helps to regulate temperature by removing heat from the surface of the Earth and distributing it into the atmosphere. The precipitation that falls to the ground replenishes surface water sources and provides essential moisture for plants, which helps to support the growth of crops and forests.

How rare is the earth’s atmosphere?

All of this is a miracle and one that many take for granted. We have not found a planet within our limited detection limits that has an atmosphere equivalent of ours – the ozone protection zones, the correct quantity of nitrogen and free oxygen built up over billions of years allowing for the abundances of life of earth, the perfect temperatures, bounteous clean water, and the list goes on. We haven’t found anything that is even close to earth’s atmosphere. Assume the most optimistic scenario as our basis – we have detected 4000 planets and none have an atmosphere like earth’s -- therefore a 1/4000 chance of occurrence. We will use this number in the table as our base case, but it is too optimistic. None of the observable planets come even close to having an atmosphere like earths’.

Our realistic chance of occurrence is far lower. With 100 to 400 billion estimated star systems in our Milky Way galaxy with 1-2 planets per star system, we have 100 to 800 billion planets in our galaxy. It is estimated that there are around 2 trillion galaxies in the observable universe. This number is based on observations and simulations and is still subject to change as more data is collected and analyzed. Currently, only a small fraction of these galaxies have been discovered, with the majority being too far away to be seen with current technology. Therefore, a more realistic assumption for probability of the earth’s atmosphere having been formed by chance is 1 in a million, as there are so many things that need to happen in sequence that are improbable to arrive at this perfect atmospheric solution. If you don’t believe this probability, believe the base case of 1/4000 as its based on empirical data (even though its incomplete and probably optimistic).

Let us use these estimates in our analysis below:

Probabilities

	Base case	Realistic case
The earth's mass is 5.972 X 10E+24 kg	0.0156250	0.00000100
Sun is 93 million miles away	0.1250000	0.00010000
Earth's atmosphere	0.0002500	0.000000100
Total probability (product of three prior variables p1*p2*p3)	4.88E-07	1.00E-16
Inverse (one in a .... chance of occurrence)	2.05E+6	1.00E+16
In words (one in...	2 million	10 quadrillion
Equivalent to rolling heads in a row	21	53
Creator probability	0.5	0.5
Creator probability/Total probability = times more likely their is a Creator	1,024,000	5 quadrillion
Coin flip time (seconds)	5	5
Years to achieve rolling above quantities in a row	0.32	1,585,489,599

With only 3 independent requirements for life to randomly form on earth out of the previously mentioned 150 requirements, the probability of has dropped to 1 in 2 million (1/4.9 x 10-7). This probability is equivalent to rolling heads in a coin toss 21 times in a row. This puts a fix on the chances that these three variables (earth’s exact mass, exact distance from sun, and atmosphere) occurred randomly in the earth’s formation. The base case scenario is wildly optimistic saying the chances are 1/8 that the earth was 93 million miles from the sun based on 1 in 8 planets in our solar system and using similar biases the mass of the earth has a 1/64 chance of being the mass it is – whereas the probabilities of these events individually are infinitely small. The ‘Realistic’ scenario presented in the table is somewhere in-between the wildly optimistic base case and the infinite – a reasonable number my math skills can handle.

If one was to consider the ‘Realistic case’, the chances of of these three variables occurring independently randomly, is now one in 10 quadrillion, which is like rolling heads until you roll 53 heads in a row, this would take some time. In fact, if you assume 5 seconds to flip the coin and record heads or tails, and do this continuously, it would take 1.6 billion years to roll 53 heads in a row. Now compare this to the age of our earth at 4.5 billion years.

In fact, it causes one to consider the possibility of there being a Creator, which without faith, is a 50:50 proposition, since it is scientifically impossible to prove there is no creator of the universe. To prove there is no Creator, you would have to travel across the entire universe and visit every solar system and every planet in the 2 trillion galaxies, to search them all to prove there is no Creator -- which might take more time than we have.. Hence, no one that has lived on this planet can prove there is no God.

Therefore, if the chances of there being a Creator of the universe is 50% -- it is 1 million times (1/4.9x10-7) more likely that there is a Creator than that these three requirements happened by chance (in our optimistic Base Case). In our Realistic Case, a Creator is 5 quadrillion times more likely than these three random events. The data seems to be pointing in a certain direction. If the data was this clear investing in the stock markets, we could all retire very early!

Whatever your own conclusions based on this post, take a minute to not take for granted our wonderful atmosphere, deeply breath in the free oxygen that seems indiscoverable in our enormous universe and enjoy the sun warming your face or the snow falling in the mountains (and sorry, about all the numbers!!).

These are just 3 of the 150 or so requirements for life to exist on earth and are only physical characteristics of the earth's relative location and atmosphere, and we have not addressed the probabilities of plant, animal and human life forming randomly within the 4.5 billion years of the earth's existence. These topics will be discussed in future posts.