TLDR ADVISORY: This article exceeds 1,000 words, and may be lengthy for some readers.
Ah, the title. The title, the title the title. See, whenever I compose one of these pieces, I endeavor to come up with a catchy title, in the hopes of snaring those few extra readers by virtue of the title’s interesting nature. In this case, I drew upon the downwards, backside-up-speak of the venerable Yoda. Depending upon both the order of these three small words and the placement of punctuation marks, the title can become a question…or a statement. As to how these three words should read, that all depends on who you ask.
There seem to be not one, not two, but three major schools of thought on the subject of whether we are alone in the universe. The fundamental, religious types will tell you that, since God created the heavens and the Earth, and created us in His image to be upon the Earth, then surely we are at the center of his creation and must be alone in the universe. (I shudder whenever I get this response, because one would think that this school of thought would, and should have died out at the same time that Copernicus’s heliocentric model of the solar system was proven as being correct. In point of fact, we’re not even at the center of anything universe-wise! In our own Milky Way galaxy, we actually reside about halfway out, on one of it’s spiral arms. If we were in the galactic center, we’d be devoured by the super-massive black hole that’s there. (1))
The hopeful romantics out there, a group which includes various conspiracy theorists, MUFON, some that are involved with SETI and others who “believe”, will reply that it is a foregone conclusion; we are not alone, and the truth is out there! The third school of thought, held by those with a pragmatic bent on scientific observation, will tell you that the possibility, while being rather remote, cannot be entirely dismissed due to the myriad of unknown variables in the universe. It is along these lines that I want to proceed and discuss with you, my fine young readers, a few of the variables that the scientific community considers when contemplating this ages-old question.
First of all, let’s look at what we know about our own home, this “third rock” from the sun (maybe I should have also titled this article “Things You Might Not Have Known”);
- We’re in what’s referred to as the “habitable”, or “Goldilocks” zone, a comfortable distance from our star where things like liquid water can form, given the right atmospheric pressure and conditions. (2)
- Speaking of atmospheric pressure, we have an atmosphere comprised of mostly Nitrogen, Oxygen and Argon, with other trace gasses thrown in for good measure. Because of the mass of our home planet, a comfortable 5.97219 × 1024 kilograms, there’s an equally comfortable 101.325 kPa (kiloPascals) of air pressure exerted. If our planet had considerably less mass, things would be a lot different!
- Our planet has a hot, two-stage core comprised of iron and nickel, which rotates. This “geodynamo” provides our planet with its geomagnetic field, which protects us from otherwise harmful solar radiation. This geomagnetic field also prevents our atmosphere from being stripped away by solar winds, which is a good thing for us. (We like to breathe, don’t we? Most of us are pretty good at it!) It is thought that this is what happened to the Martian atmosphere long ago, as geological processes like plate tectonics and core spin ground to a halt. (3)
- Our planet is part of a system of planets which orbit a single star, a relatively small G-type main-sequence star known as a “yellow dwarf”. While most other stars in the observable galaxy are part of binary and ternary star systems, our yellow dwarf seems to be in the small minority of systems with only a single star. (4)
- Our blue marble spins on an axis, at about a 23° tilt, which gives us our seasons. We spin around once every 24 hours, which gives us our days and ensures that most of the planet is equally bathed in life-giving sunlight. (The polar regions get far more or far less sunlight at certain times of the year, also due to the axial tilt, and the manner in which we orbit the sun.)
In other words, the conditions here are like Baby Bear’s porridge; just right. Any closer to the sun, and we would bake. Any farther, and we would freeze. If our core stopped spinning, then our magnetosphere would collapse, and that nice, breathable atmosphere would be whisked away by the solar winds. If our planet did not spin, then half of the planet would always be hot, the other half, always cold. This would change only gradually, over the 365-day period of orbit around the sun. There are several conditions that have to be just right, for life to not only develop, but to thrive.
Here’s another thing to consider; when we talk about “life on other planets”, people’s minds always jump to the idea of “little green men”, “the greys” and other concepts of sentient, developed lifeforms. What about the smallest forms of life, microbial life? What about plant life? There could very well be life on other planets, just not the kind of life that people are expecting!
Now ask yourself; what is the likelihood of there being an extra-solar system somewhere out there, with a single sun, with a planet in its habitable zone possessing a two-stage metallic core, which spins on an axis and has the right mass, and an atmosphere at just the right pressure, that liquid water can exist with some modicum of stability? Out of all of the exoplanets discovered so far by the Kepler mission, how many of them meet these criteria?
It’s easy to dismiss or to take for granted, the several things that make our home a home. At the end of the day however, they all still figure in to the equation. Given all of this, coupled with the vast distances between the stars, is the idea of “contact” a likelihood? Are we alone / alone are we / alone we are / we are alone…?