As far as we know, our planet is the only celestial body that gives birth to life.
It is true that this makes the planet unique, but is it really the case?
Is life more common and older every day than we first thought?
The first evidence of life on Earth is very close to the formation of the Earth. While there are several theories that attempt to explain the early origins of life on Earth, some scientists speculate that our planet may be a protective haven for life that originated elsewhere long ago. Allow us to introduce you to the concept of "Seeds of Life".
According to current estimates, our planet is about 4.5 billion years old. Earth's early history was filled with intense volcanic activity and meteorite bombardment for about a third of the time. Interestingly, this is not conducive to the rise and preservation of life. However, things soon stabilize, allowing the liquid water to settle and collect on the Earth's early crust.
Just a few hundred million years later, the conditions seem to have been "just right" for the first "seeds" of life to rise on Earth. Little is known about these very early life forms, but most scientists agree that the world is most likely ruled by microbes because of the lack of a better term.
About 3.7 billion years ago, we got the first clear signs of life, whether giving or taking. As far as we know, these fossils are nothing more than a series of tubular structures, the oldest fossils ever discovered. While controversial, there are slightly younger fossils known as "stromatolites" (sticky mats of microorganisms) that date back about 3.5 billion years.
The early Earth was very hostile to life. (*NASA Goddard Space Flight Center Francis Reddy, Wikimedia Commons).
We know from the fossil record that the earliest cyanobacteria (photosynthetic bacteria) appeared about 2.4 billion years ago. Their evolution will have a revolutionary impact on life on Earth. They were the first organisms to be able to generate energy directly from the sun and release oxygen as waste.
This will result in the dumping of free oxygen into the atmosphere in large quantities over thousands or even millions of years, leading to what geologists call a "great oxidation event." In the Paleoproterozoic (25 to 1.6 billion years ago) has been found in large quantities of iron-rich sedimentary rocks.
As the conditions for more advanced multicellular life are ripe, the rest, as they say, is history. It's all very remarkable, but is it possible that life is much older than Earth? Some scientists believe this.
But before we get into this field, we need to briefly explore what life is. You may have learned in school that life is anything that can move, reproduce, respond to stimuli, absorb nutrients, excrete, breathe, and grow. But, believe it or not, there are about 200 academic definitions of what life is.
This has led many scientists to question whether prions or things like viruses are technically "alive". While they meet some of the above criteria, they don't meet all of them. For example, viruses are sure to multiply, can respond to stimuli (in the case of the herpes virus), and can evolve.
However, they are completely dependent on the host for survival and cannot metabolize independently. However, it has also been suggested that they may have been one of the earliest life forms ever evolved.
However, it is important to point out that other biologists believe that viruses may be a dysfunction in early cell reproduction and have become a catalyst for the evolution of life on Earth. However, this is a very fruitful area of study, and it is, so to speak, a very interesting field.
In any case, most biologists would agree that life is anything that is broadly influenced by Darwinian evolution. Broadly speaking, it is the idea that an organism or "species" changes over time, giving rise to new species and sharing a common ancestor.
If we accept this premise, then we can begin to explore the possibility that life may actually predate life on Earth by billions of years. Let's see how.
Some scientists believe that the first life may have been formed long before the birth of the Earth. Abraham Loeb, an astrophysicist at Harvard University, argues that, in theory, life is almost as old as the universe itself.
To answer this question, let's take a brief look back at the history of the universe and explore when life may have first appeared, with an emphasis on what is possible. Hold on; This is about to get crazy.
Will life be as old as the universe? （*pixelparticle/istock)
The story goes like this, after the "big **", the universe was engulfed by a superheated gas called plasma. This plasma gradually cools and emits light, which we now call cosmic microwave background radiation (CMB).
It was very hot at first, and as the universe expanded, it gradually cooled. Today, the temperature in the CMB is very low, about minus 454 degrees Fahrenheit (minus 270 degrees Celsius; 3 Kelvin).
But logic tells us that there is a specific phase in this cooling process, which lasts for about 7 million years, and the temperature is the optimal temperature for life to exist. A "Goldilocks Window", if you will.
As Loeb suggests, about 15 million years after the "big **", the temperature of the CMB is similar to that of a warm summer day on Earth. That's about 31 to 211 degrees Fahrenheit (0 and 100 degrees Celsius; 273 and 373 Kelvin). This temperature range is crucial because it allows liquid water to exist on exoplanets in the ancient universe.
According to **i Loeb, this is important because it shows that if rocky planets had existed during that time, the heat provided by the CMB would have been sufficient to maintain a surface temperature suitable for liquid water, regardless of their location within the habitable zone of the parent star.
If the conditions are right, as on Earth, the possibility of life forming on them would be a good option.
It's an interesting idea, but it does depend on the possibility that rocky planets might form early in our universe. It also relies on enough heavier elements like oxygen, carbon, silicon, nitrogen, etc., to survive life because we know it is viable.
This may be the "Achilles heel" of the theory, because only tens of millions of years after the "big **", the first stars formed from hydrogen and helium. Prior to this, our current understanding of the evolution of the universe meant that there were no planetary heavy elements at that time. Most scientists believe that heavier elements such as carbon began to form around 12.5 billion years ago.
However, Loeb proposes to test his theory by identifying planets in the Milky Way orbiting low-metal stars. There is also the possibility that the "pockets" or hot spots (called blue dots) of the CMB have existed for billions of years, allowing heavier elements to form and life to rise.
Leob's ideas also challenged other "sacred" notions in astrophysics, such as the anthropic principle and cosmological constants. However, he believed that life could have formed in the early universe, even if the conditions were very different from what we observe today.
Are there ancient aliens out there waiting to be discovered? This challenges the anthropological argument that the observations of cosmological constants are necessary for the existence of life. Loeb argues that even if the cosmological constant is a million times greater than what we have observed, life may have already appeared.
While this theory is hotly debated today, it does raise some interesting questions about the nature and origin of life in our universe. It also supports other interesting ideas about the origin of life on Earth. This could mean, for example, that the pan-species hypothesis (or the life sown between planets) may have some merit. It can also provide hope for those who believe that the universe is full of life, waiting for our distant descendants to discover.
This is your fate today.
So, are we alone in the universe? Is our planet as special as we think it is? Let's hope so; Otherwise, we and our descendants will be disappointed and lonely until the end of the world. This is not a very tempting prospect.
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