According to a new theory, if conditions had been just a bit different, life could today exist on a lush and different Venus and Earth would be a dead, inhospitable planet.
According to researchers, tiny evolutionary alterations could have changed the fates of our planet and Venus.
The new study could facilitate the search for alien lifeforms elsewhere in the universe and help rewrite the theory of the Goldilocks zone where researchers maintain life is most likely to exist.
The hypothesis proposed by Rice University scientists and their fellow colleagues published in Astrobiology looks at the Goldilocks zone and potential zones where life can exist.
The famous Goldilocks zone has long been considered as the sweet spot around a star that is not too warm, nor too cold, rocky and with just the ideal conditions for maintaining surface water and a human-breathable atmosphere.
However, Rice Earth scientist Adrian Lenardic says that the description that defines the Goldilocks zone is too limiting since researchers have not been able to calibrate it.
According to Lenardic and other scientists, habitable planets may, in fact, be located outside the so-called Goldilocks Zone in extra-solar systems. Lenardic and his colleagues believe that planets farther from or even closer to their stars than Earth may contain the ideal conditions for life as we know it to exist.
‘For a long time we’ve been living, effectively, in one experiment, our solar system,’ he said.
‘Although the paper is about planets, in one way it’s about old issues that scientists have: the balance between chance and necessity, laws and contingencies, strict determinism and probability.
‘But in another way, it asks whether, if you could run the experiment again, would it turn out like this solar system or not? For a long time, it was a purely philosophical question.
‘Now that we’re observing solar systems and other planets around other stars, we can ask that as a scientific question.
‘If we find a planet (in another solar system) sitting where Venus is that actually has signs of life, we’ll know that what we see in our solar system is not universal,’ he said.
In order for us to find possible habitable planets, it is necessary to expand the notion of habitable zones. Researchers determined that life on our planet isn’t necessarily possible based solely on the Goldilocks concept. In fact, according to scientists, a small change in the conditions that existed in the early formation of the planet may have made Earth completely inhospitable.
Looking at our solar system, researchers believe that a similar miniature variation could have changed the fortune of Venus, our planets closest neighbor in the solar system, preventing it from becoming a burning desert with a poisonous atmosphere for humans.
The paper published in Astrobiology questions theories that tectonics are one of the critical reasons why Earth can sustain life.
‘There’s debate about this, but the Earth in its earliest lifetimes, let’s say 2-3 billion years ago, would have looked for all intents and purposes like an alien planet,’ Lenardic said.
‘We know the atmosphere was completely different, with no oxygen.
‘There’s a debate that plate tectonics might not have been operative.
‘Yet there’s no argument there was life then, even in this different a setting.
‘The Earth itself could have transitioned between planetary sStates as it evolved.
‘So we have to ask ourselves as we look at other planets, should we rule out an early-Earth-like situation even if there’s no sign of oxygen and potentially a tectonic mode distinctly different from the one that operates on our planet at present?
‘Habitability is an evolutionary variable,’ he said.
‘Understanding how life and a planet co-evolve is something we need to think about.’
‘Our paper is in many ways about imagining, within the laws of physics, chemistry, and biology, how things could be over a range of planets, not just the ones we currently have access to.
‘Given that we will have access to more observations, it seems to me we should not limit our imagination as it leads to alternate hypothesis.’