Ancient Earth Study Suggests Our Odds of Finding Aliens Close to Us Are Greater Than We Ever Imagined
The only planet in the known universe that has been definitively proven to shelter life forms is our own.
This being the case, it's possible to take a guess at how rare aliens might be, based on how unusual our own planet is. If there are a lot of different worlds across the cosmos that are similar to our own, and that developed along the same lines when they first formed, there's a better chance that our own existence is not an anomaly.
Sadly, the majority of scientific evidence up to this point suggests that our world was lucky to see life develop in the first place. The so-called "Cool Earth" theory argues that, because the sun was smaller, dimmer, and weaker when our planet formed, early Earth would have been a cold environment that by all rights shouldn't have been capable of supporting life.
Whatever happened to provide the spark that developed into our earliest ancestors must have been a complete fluke.
Now, though, a new study suggests that the opposite is true. University of Washington graduate student Joshua Krissansen-Totton and his team of researchers have published a paper estimating the temperatures found on early Earth based on evidence from the sea floor.
Astrophysics (@UoE_Astro) October 25, 2017
Their findings suggest that in its infancy, heat from within the planet's core would have meant that the Earth was actually very warm, with temperatures of all the way up to 160ºF.
According to the paper:
These claims are based on an analysis of the seafloor, and how it has worn down over time. As the planet has aged, the sea floor has expanded, but it's still possible to trace back its conditions at the early days of the planet by looking hard at how it initially formed.
The study also suggests that the acidity of the seafloor was fairly neutral during the first period of the Earth's development, helping the oceans to be fertile enough to support life. Apparently, conditions would have been around 6 to 7pH, the perfect acidity to allow life to thrive.
If this study is correct, it dramatically increases the likelihood of nearby aliens. Assuming that planet Earth was warm and tropical following its initial creation, other worlds could also be warm enough to support life, meaning that there's a greater chance that other planets would go through a similar process to our own.
That said, this doesn't mean that any planet could potentially hold life, as there's more to the development of living creatures than simple temperatures. An alien world would also need the right kind of atmosphere; protection from solar flares and asteroids; and, crucially, the right mix of chemical compounds - the so-called "building blocks of life" to enable life forms to develop.
As for how often these conditions are met, it's difficult to say. We've observed plenty of "goldilocks" planets that are the right distance from their stars to develop life, but thus far, without any definitive proof of aliens on another world, we can't begin to generate a solid, concrete estimate as to how many planets in our vicinity might hold alien life.
For now, all we can do is hope for the best - hence the existence of this paper, and plenty more speculative research like it.