Researchers have possibly found why, despite there being a high probability that alien life exists, there has been no conclusive evidence that proves their existence: life on Earth was premature.
Here are the facts: The Earth is 4.5 billion years old, and the universe was born 13.8 billion years ago.
With that knowledge, many have long believed that the universe is primed for life right now and that Earth and its life forms were late to the party. However, a recent analysis by scientists at the Harvard-Smithsonian Center for Astrophysics, which was published online in the Journal of Cosmology and Astroparticle Physics, suggests that, rather than being late, humans were a bit too early.
"If you ask, 'When is life most likely to emerge?' you might naively say, 'Now,'" lead author Avi Loeb, said in a statement released Monday. "But we find that the chance of life grows much higher in the distant future."
It's All In The Stars
The team came to its conclusion by applying its knowledge of the evolution of the early universe and the lifespan of stars: the higher the mass, the lower the lifespan. Knowing that life first became possible 30 million years after the Big Bang occurred and will cease to exist 10 trillion years from now, the team designed a model to understand when on the timeline between these two points that life would be most likely to form.
The results found that the most important variable in the equation was the mass of the stars that would facilitate such life. The first generations of stars were too big, thus burning brightly and quickly, and would ultimately burn out completely before life could have a chance to evolve. Conversely, smaller stars, which burn slowly, have exceptionally long lifespans, allowing life on orbiting planets to grow. For example, a star with a mass 10 percent of the sun's can burn for 10 trillion years.
Ultimately, the new model suggested that the chance of life grows higher in the future — by a factor of 1,000, to be specific.
The Low-Mass Dillemma
After seeing what the model suggested, it would be quite easy to question as to why we aren't living in the future next to a low-mass star. The reason for this is situated on our current understanding of such stars (as well as an avenue for future research).
As of now, aside from knowing that low-mass stars have high lifespans, we also know that, when these stars are young, they emit strong flares and ultraviolet radiation that can strip the atmosphere from any rocky planet nearby. What's more, the star's gravity could pull much harder on one side of the planet, causing more volcanic activity that could lead to a runaway greenhouse effect and the oceans boiling off.
It's unclear if there is any form of life that could endure such conditions, and if there are, we certainly haven't come across any indications of their existence yet.
What About Humans?
As if we needed something else to stroke our egos, opposed to everywhere else in the universe that seemingly has no life to speak of, humans are "thriving" here on Earth, well before the model suggests we should.
The reason for this is unclear, and Loeb was quite honest in his assertion that our birth and evolution might have all come down to luck or we're simply premature.
No matter how you slice it, the results of this research so far are quite clear: humans are weird. Fortunately, that is exactly what it is trying to address: "This research has a bigger significance," said Loeb: "whether we're special or typical."
