In a sharp departure from the usual themes of this blog, I’d like to take on an issue that’s been bugging me for a while.
First and foremost, let me ask for forgiveness from those that know better than me: I’m trying not to bore readers rigid with too much detail, so allow me some room for approximation.
I’m taken aback by the universe, and the sheer, enormous – infinite in fact – size of it. I’ll expand on the theory that the universe is infinite, in space and time, in another rambling in the future. I’m also fascinated by probabilities, permutations and possibilities, and their relation to infinite sizes.
Please bear with me as I slowly unfold the many layers of my thoughts in front of you.
We know that Earth is quite unique in our solar system. First and foremost, we sit in what’s described as the “Goldilocks Zone”: not too cold, not too warm, just at the right distance from our planetary system star, the Sun.
But so is Venus, and you can’t live there. The surface is at an infernal temperature of over 450° C, the atmospheric pressure is a hundred of times higher than Earth, the atmosphere is 98% carbon dioxide and it rains concentrated sulfuric acid.
How did that happen? Well, we got lucky. In the initial pinball machine that was the formation of our solar system, many protoplanets – still in plastic, molten rock condition – collided with other, smaller bodies, often inglobating them. In rare occasions, the relative size of the colliding bodies was not indifferent, and the hit caused orbit, spinning angle and direction changes for both, with shrapnels flung across the forming solar system to collide with others.
All these random blows have conjured to make our planet spin every 24 hours, revolving on its axis in the same direction of our revolution around the Sun and at an angle that has been oscillating since between 20 and 25 degrees from perpendicular.
This didn’t happen for Venus, a planet of a comparable size to Earth very close to that Goldilocks Zone that could host life. Venus spins very slowly, in opposite direction to its orbit around the Sun. This can only have been caused by a substantial glancing blow by another smaller protoplanet because all other planets in our solar system rotate in the same direction they revolve. It’s in the mechanics of the formation of our solar system, so Venus is an anomaly.
Another thing Venus is missing is a satellite of the size of our Moon and its beneficial consequences. Our satellite stabilises the position of our revolution axis, causes tides thus natural shuffling of our ocean waters and waves on our seashores, and provides reflected sunlight during the night.
Again, the Moon is just in the right position, not too close to cause cyclic deformation to our planet’s crust through a stronger gravitational pull, causing geothermal and volcanic activity, and pulling the oceans so strongly to generate enormous, devastating tides. But it also settled on an orbit that is not too far to be effective or that rapidly expands and leaves us without it. Just right.
Despite missing all the above, Venus would still have been able to harbour proto-life, as we have proof that in the distant past it was covered in water in its liquid state: oceans, lakes, rivers, fog, clouds. Where has it gone now? Well – again – Earth has a superhero feat that Venus misses: a power shield.
Between the many bodies our planet took in its initial formation, some of them were made of large quantities of iron and nickel, and because of their heavier atomic weight, they concentrated themselves in the centre of our planet, the core, encapsulated by a thick, dense layer of semi-liquid, viscous but fluid magma acting like a damper and a lubricant at the same time.
This ball of highly compressed, superheated metals, spinning faster than the outer layers of our planet, generates a magnetic field that shoots out from the North and loops around it, like a doughnut, to reenter from the South. It’s not perfectly aligned because the magnetic Poles don’t correspond with the axis of our planet rotation, but it’s pretty close.
This magnetic field acts as a very powerful shield against the deadly effect of the solar wind, an extremely violent stream of high-velocity particles the Sun is blasting in many directions. Don’t forget that our star is, in fact, a mindbogglingly giant nuclear reactor, an explosion that has been going on for billions of years, with all the violence involved. The Northern Lights are a constant reminder of this phenomenon.
As with the Moon, this magnetic field is strong enough to deflect the solar wind, but not so strong to influence or damage the tools that we use. Just right.
The poor Venus doesn’t have a magnetic field powerful enough to deflect this neverending blast of solar wind, so its water has been stripped, relentlessly sandblasted away from its atmosphere. With clouds leaking into space, the lost cover from the Sun heat accelerated water evaporation, and in an infernal loop of self-annihilation Venus lost all its water and with it the ability to spawn life.
A Venusian “day”, or its rotation around the axis, lasts longer than its “year”, or its revolution around the Sun: 243 against 224.7 Earth days. However, because it spins backwards, a “day” on the surface of Venus lasts just over 115 Earth days. In practice, Venus has the same spot facing the Sun for a very long time, but despite being exposed to a direct sunlight for longer periods, this is filtered by a dense layer of sulfuric acid clouds and a thick carbon dioxide atmosphere, so the heat irradiation from the Sun is scarce and distributed evenly.
Again because of the atmosphere density and other environmental factors, the temperature on Venus “night” side is not as cold as you would imagine could happen in an area that’s been in the dark for hundreds of Earth days. All the above means that the recirculation of gases on the surface is slow and the atmosphere is stagnant.
This doesn’t happen on our planet: although the speed it rotates on its axis doesn’t allow for a lengthy exposure to sunlight to accumulate heat in significant amounts against its mass, or the short nights cannot leak massive amounts of heat into space, the consistent and fast thermal swings between day and night recirculate the atmosphere between areas and altitudes pretty quickly. Especially the thermal inversion happening near the seaside is of massive benefit to disperse pollutants and rejuvenate the air we breathe.
Again, not too much or too little thermal excursion between day and night. Just right.
A further difference between Earth and its twin planet Venus is very important. Our twin planet’s rotation axis is almost perpendicular to its planar orbit, just 3 degrees off, while ours is currently at 23 degrees. This is not an irrelevant detail but in fact the main key for life to take hold and flourish on our planet.
Thanks to that specific angle, we have seasons that cyclically change our environment in a significant but not too disruptive way. Why is this crucial? Because without gentle seasonality, plants wouldn’t blossom, bear fruit, shed foliage to be composted, and finally hibernate ready for another cycle.
Harsher seasons would cause extensive recurring glaciation in winters and devastating bushfires in summer, periodically wiping out life in large swathes of the planet and reducing the surface area with liquid water.
On the other hand, close to no seasonality severely limits the type of flora and fauna that can flourish, reducing the biodiversity and undermining the sustainability of life on the planet.
Seasons are the mechanism that triggers the constant regeneration of life, for flora and fauna, exactly like tides and waves stop water from becoming stagnant and poor of oxygen.
The angle the Earth spins on its axis against the orbital plane is just about right. Not too shallow, not too deep. Just right.
The very last element I offer for your consideration is the passing mention I made of moonlight. Far from being a mere romantic mention of our Moon’s beauty, the sunlight reflected back to Earth during most nights by a bright white satellite so close to our planet has supplied our ancestors with just enough light to see and defend themselves from night predators.
There are many other minor events that facilitated the evolution of humans on Earth, including the extinction of dinosaurs, against whom we would have had no chance to survive.
Every single condition for the creation and sustenance of intelligent, self-aware life on our planet happened at just the right time, in just the right order, at just the right place, in just the right amount. Its twin planet Venus missed only a handful of these and is a scorched, barren, desolate land of fire, crushing pressure, toxic atmosphere and corrosive rain.
It’s entirely possible that some form of very primitive life could survive in such environment: after all, here on Earth, there are bacteria growing near volcano fissure vents and is believed that early life on our planet started near hydrothermal vents in the dark, high-pressure depths of the oceans.
However, as we have seen with the Venus example, so close to us, the number of conditions to be entirely satisfied for a planet to start, evolve and sustain intelligent, sentient life are astoundingly complicated, and the probability that this could have happened somewhere else in the universe are seriously slim, even if we assume the Universe is infinite. Moreso, if its size is infinite, similarly infinite are the possible permutations of the fundamental conditions and timeline of events to create another Earth-like planet somewhere within it.
If to this we add that the timescale of human existence in the universe lifespan is so minute to be entirely insignificant and non-measurable, the possibility that, somewhere in this infinite universe, there could be a life form similar to ours that we can get in contact with right now, makes this occurrence even slimmer.
Another small thing is in our way: the distances between us and other astronomical bodies that could be inhabited by an equally intelligent life form are so big that, before we see, feel or hear them, millions of years would have passed.
So, if we get a signal from a distant galaxy sent by an intelligent lifeform, it’s either too late – they’re long gone – or if they’re still there, and millions of years ago they sent a signal we can capture now with a compatible equipment, they would have now reached a level of technology, evolution or consciousness that any contact with them would be meaningless, if not even impossible.
This is my frustration. Even if I don’t have an advanced knowledge of the cosmos, I can see that the eventuality that we can contact something out there is slim, thin, minuscule, or even non-existing. I’m resigned to the thought that here, now, We Are Alone.
This is crushing and terrible, but also enormously empowering. Throughout this infinite universe, full of possibilities, at this very moment, we are living a unique, special, exceptional event that will never, ever repeat itself.
Make it worth. Make it count.