Is all life in the universe related, and from the same single point of origin?
Life is likely to have formed in the universe as soon as the right conditions arose. And that will have been soon after the first supernovae, when the violent deaths of those stars spread out the heavy and complex elements that are considered essential for life to form.
The oldest supernovas studied occurred 10.5 billion years ago, just two billion years after the formation of the universe itself. The planetary systems that formed soon after are likely to be the ones to evolve the first ever life in our universe.
For life as we know it to survive there needs to be a certain temperature range, plenty of liquid water, and the right mix of gasses. And this state needs to be maintained for hundreds of millions of years or more for anything other than the simplest types of life to form.
How often life begins (abiogenesis) once the conditions are right is unknown. It is possible that as soon as the conditions are right then life emerges. If this is the case then life will have arisen quite often, and is probably flourishing on billions of planets right now. But despite a huge amount of research and experimentation this has not yet been shown to be the case.
It's quite possible that something else is required, something we are yet to identify, that makes the process extremely rare. So rare, in fact, that it has only ever happened once.
If that is the case then the only way life could become widespread is via panspermia: the distribution of life via dust and meteoroids as collision debris is ejected into space, carrying primitive but hardy life with it. Life on Earth could well have arrived this way. It could have been travelling through interstellar space in a dormant state for many millions of years. And the world where it came from could itself have been seeded in such a way.
Life on our planet could be descended from life that originated on a planet millions of light-years away, and it could have evolved billions of years before even our sun was born.
Ultimately there could be just one source of life in the universe, formed soon after those first supernovae. All life in the universe, at least all life of the kind that is found on our planet, could be related to that single abiogenetic event.
The only life we know of and have studied is on our planet. The biochemistry of all of life on Earth is carbon-based with water as a solvent and DNA or RNA to define growth, structure and function. But life is theoretically possible with other forms of biochemistry, which would increase quite significantly the number of planets and locations where life could survive. Silicon, like carbon, can create molecules large enough to support biological information, and ammonia or methane are suitable alternative solvents to water.
There is one place in our Solar-System where an alternative kind of life could be present right now: Saturn's moon, Titan.
This possibility is something that needs investigating (see my previous article 'Human Colony on Titan' where I mention the indigenous life that we could encounter there). It is so cold on Titan that the lakes consist largely of methane rather than water, and the thick atmosphere (thicker than Earth's) provides great protection from cosmic rays and small meteorites. Saturn's magnetosphere also provides some shielding. It is the most likely place for us to find non-Earth-like life in the Solar-System.
Panspermia could also be responsible for life on Titan. If methane-based life is abundant then it too could have arisen around the same time as water-based life and been spread aboard collision debris in the same way. If there is indeed something special and extremely rare that needs to occur for life to form then methane-based life could have a single point of origin in just the same way as water-based life. All life, no matter what biochemical base it has, could be related to a single distant ancestor for that biochemical type, perhaps even in the same star-system that the other forms of life arose. Something very unique could well have occurred there: the event that kick-started life - the spontaneous occurrence of something profound that enabled non-living matter to become life.
Whether or not that is the case could have profound ramifications for our species as we embark on interstellar colonisation. We could find that life is present in most of the star-systems we visit. If so, will it be beneficial, a hindrance, or a danger that's lethal to our species? Or we could find that each and every planet that we visit is barren of life, no matter how Earth-like it appears to be. That could be a good thing, allowing us to colonise suitable planets without having to deal with strange and potentially harmful lifeforms. But it would also mean that we are truly alone.
Earth could end up being that single source of life in the universe.
That is quite a profound thought...
Life is likely to have formed in the universe as soon as the right conditions arose. And that will have been soon after the first supernovae, when the violent deaths of those stars spread out the heavy and complex elements that are considered essential for life to form.
The oldest supernovas studied occurred 10.5 billion years ago, just two billion years after the formation of the universe itself. The planetary systems that formed soon after are likely to be the ones to evolve the first ever life in our universe.
 |
| The first supernovae more than 10 billion years ago created the elements essential for life to begin |
For life as we know it to survive there needs to be a certain temperature range, plenty of liquid water, and the right mix of gasses. And this state needs to be maintained for hundreds of millions of years or more for anything other than the simplest types of life to form.
How often life begins (abiogenesis) once the conditions are right is unknown. It is possible that as soon as the conditions are right then life emerges. If this is the case then life will have arisen quite often, and is probably flourishing on billions of planets right now. But despite a huge amount of research and experimentation this has not yet been shown to be the case.
It's quite possible that something else is required, something we are yet to identify, that makes the process extremely rare. So rare, in fact, that it has only ever happened once.
If that is the case then the only way life could become widespread is via panspermia: the distribution of life via dust and meteoroids as collision debris is ejected into space, carrying primitive but hardy life with it. Life on Earth could well have arrived this way. It could have been travelling through interstellar space in a dormant state for many millions of years. And the world where it came from could itself have been seeded in such a way.
 |
| A procaryote: a simple but hardy life form that can survive in some very extreme conditions. Could such simple archaeal/bacterial life have spread throughout the universe from a single point of origin? |
Life on our planet could be descended from life that originated on a planet millions of light-years away, and it could have evolved billions of years before even our sun was born.
Ultimately there could be just one source of life in the universe, formed soon after those first supernovae. All life in the universe, at least all life of the kind that is found on our planet, could be related to that single abiogenetic event.
The only life we know of and have studied is on our planet. The biochemistry of all of life on Earth is carbon-based with water as a solvent and DNA or RNA to define growth, structure and function. But life is theoretically possible with other forms of biochemistry, which would increase quite significantly the number of planets and locations where life could survive. Silicon, like carbon, can create molecules large enough to support biological information, and ammonia or methane are suitable alternative solvents to water.
There is one place in our Solar-System where an alternative kind of life could be present right now: Saturn's moon, Titan.
 |
| Saturn's moon, Titan, is the most likely place in the Solar-System where we might find non-Earth-like life, based on methane/ammonia rather than water |
This possibility is something that needs investigating (see my previous article 'Human Colony on Titan' where I mention the indigenous life that we could encounter there). It is so cold on Titan that the lakes consist largely of methane rather than water, and the thick atmosphere (thicker than Earth's) provides great protection from cosmic rays and small meteorites. Saturn's magnetosphere also provides some shielding. It is the most likely place for us to find non-Earth-like life in the Solar-System.
Panspermia could also be responsible for life on Titan. If methane-based life is abundant then it too could have arisen around the same time as water-based life and been spread aboard collision debris in the same way. If there is indeed something special and extremely rare that needs to occur for life to form then methane-based life could have a single point of origin in just the same way as water-based life. All life, no matter what biochemical base it has, could be related to a single distant ancestor for that biochemical type, perhaps even in the same star-system that the other forms of life arose. Something very unique could well have occurred there: the event that kick-started life - the spontaneous occurrence of something profound that enabled non-living matter to become life.
Whether or not that is the case could have profound ramifications for our species as we embark on interstellar colonisation. We could find that life is present in most of the star-systems we visit. If so, will it be beneficial, a hindrance, or a danger that's lethal to our species? Or we could find that each and every planet that we visit is barren of life, no matter how Earth-like it appears to be. That could be a good thing, allowing us to colonise suitable planets without having to deal with strange and potentially harmful lifeforms. But it would also mean that we are truly alone.
Earth could end up being that single source of life in the universe.
That is quite a profound thought...
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