It is an irony that despite our authors dishing
out books and novels on extra-terrestrial life forms in the thousands, there is
not a single instance where our scientists could credibly establish that alien
life exists. Instead we only have Hocus Pocus stories about UFO sightings
mostly in the USA none of which have any credible proof.
Yes, as life exists on the Earth, it is a
logical necessity that it should exist in other planetary systems going around
other stars like the Sun which are too numerous in the Universe. However, there
is an immense problem in finding life in other planets if the life forms there
are under developed, because they give out very less in terms of signatures
(markers that life leaves around) that can be seen as life from other planets.
Living beings on Earth are so minuscule
compared to the planet that they inhabit that it is actually like searching for
a needle in a haystack. For example the weight of all the living organisms on
earth is estimated to be 550 billion metric tons or 55* 10 raised to the power
of 9. While the Earth weighs about 6.5 billion trillion tons OR 6.5* 1021
tons. That means earth has almost a trillion times higher mass than the entire
life on earth combined. So if any alien life forms are searching for life on
Earth, for them it would have been very difficult to find us if we never had
any electricity that lights up the planet in the night. But again, even those
so called numerous lights cannot be seen from the nearest star to us.
Another thing that is hindering our discovery
of other life forms is our bias. We tend to interpret life as it had developed
on our planet and place riders on its appearance and composition.
We interpret the creation through Chemistry
which is subject created by the human brain. We interpret the interaction
between molecules in a certain way as per our structured thinking, but are not
in a position to visualize how the structure of matter operates from another
view that is totally different from ours. But then, in this we are constrained
in our thoughts and cannot think differently than what we do.
Earth was formed 4.5 billion years ago (this is
also called GA or Gigannum) while life began on the Earth some 3.8 billion
years ago. So for 700 millions of years after earth formed there was no life. At
its formation earth had an atmosphere that was intensely hot and it was far
denser than the current atmospheric blanket.
Active volcanoes spewed out massive amounts of steam, CO2, Methane &
Ammonia into the air. There was no free Oxygen then as plants and Oxygen
producing photosynthesis had not yet evolved.
As the hot earth cooled down, the huge amount
of water vapour in the air began to condense and fall as rain. That formed the
first oceans. The high energy radiation from the young Sun broke down volcanic
ammonia molecules and slowly freed the Nitrogen in the atmosphere.
Life is mostly emptiness pretending to be
solid. The thing called “You” is 99.9% nothing. Your atoms are separated by
distances that proportionately make Galaxies look crowded. But somehow this
organized void learnt to want things to grow and to think.
Life started at the very edge of nothingness
itself, in structures so tiny that they barely qualify as things at all. 20
nanometers ( 1 nano meter equals 10-9 mtrs or one billionth of a meter) . These things/proto
life are called Nanobes and they are tiny threadlike structures found in rocks
and sandstone deep underground. This is the smallest level where life can physically
exist. Below this size it is so small that it is impossible for any metabolism
to exist and Physics breaks down. It is a fundamental law written into the laws
of Physics themselves.
According to an article published in 2024 in
“Nature”, the minimum viable proto cell
requires about 4 basic components; A membrane to contain it, genetic
material to store information, enzymes to catalyse reactions, and Ribosomes to
build proteins. If these are packed into anything less than 20 nanometres the
cell just cannot function. However about 4 billion ago, life started anyway and
Chemistry found a way to be Biology.
We know this because the genetic code is
universal. Everything from bacteria to blue whale uses the same basic molecular
alphabet, the same 20 amino acids, the same 4 nucleotide bases, the same
genetic code that translates DNA sequences to proteins. This universality is
almost impossible to explain unless all life descended from a common Ancestor.
Scientists call this hypothetical organism LUCA (Last Universal Common
Ancestor).
Researchers at the University of Bristol led by
Dr Timothy Lenton developed algorithms that can trace the genetic sequences
backward through time. Then they calculated back as to how much time this
process from the non-living to living would take. LUCA is incredibly simple, simpler than any
living thing that we ever found. It had fewer than 400 genes compared to the
4000 found in the simplest modern bacteria. It was tinier than any cell that
exists today. It was found by the researchers that LUCA was somewhere between
20 and 50 nanometres in diameter.
Amazingly LUCA outsourced most of its
requirements from the environment. This is the RNA world hypothesis proposed by
Nobel winner Walter Gilbert in the 1980”s. Before DNA, before proteins, before
the complex molecular machinery of modern life, there was RNA, a molecule that
can store Genetic information like the DNA and catalyse chemical reactions like
proteins. But the RNA is fragile and can be easily destroyed by the
environment, so how did it survive?
In 2024, researchers from the University of Colorado
have shown that RNA could be stable and functional at temperatures exceeding
100 degrees centigrade, but under specific conditions. These exact conditions
exist on the walls of the alkaline hydrothermal vents, deep sea structures
where mineral rich water erupts from the ocean floor. This is where there are perfect conditions
exist. However, the proto cells that form are incredibly small and are from 10
to 50 nanometres across.
This is also known as Omni. Dr Jack Jostack’s
team at the Massachusetts general hospital embarked on a journey to build a
proto cell, the complete configuration that can be absolutely genuinely alive
at the smallest level. It is they arrived at the 20 nanometres barrier beyond
which Physics breaks down.
How did such a profoundly small thing pass on
to become higher level of cells? By cooperation. They were too small to thrive
independently so they outsourced their functions across thousands or millions of
such organisms. Dr Sara Imari Walker of
the Arizona State University is developing theoretical framework for
understanding the transition from non-living to the living.
Her research published in Nature Physics in
2024 suggests that life is not the property of individual molecules. It is
emergent property of information processing networks. So the first cells were
living systems together to produce something larger than the sum of their
parts. It is like a distributed computer with many processors. Early life
worked the same way. When two protocells come into contact their contents mix,
allowing the materials to flow. This was replicated in the laboratories.
That means early life forms could overcome the
limitations of Physics via sharing of resources like a cellular internet. But
how did these networks stay coordinated? How did they function as a single
cell? This is answered by latest research on Horizontal Gene transfer. In
modern biology genetic information flows vertically from parent to offspring but
in the earlier stages of life genetic material flowed horizontally flowing
between different unrelated organisms. It was the primary mechanism for genetic
inheritance. Dr Carl Wos revolutionised our understanding called
it the progenate stage of life, a phase where genetic innovation spread rapidly
through entire populations. In this the genetic information is passed on to the
entire network and not just to the offspring. The network as a whole becomes smarter,
more efficient and more adaptive.
The fossil evidence supports this picture. The
earliest signs of life dating 3.8 billion ago are not isolated but are vast
microbial mats, communities of organisms working to transform their environment.
These structures called Strumatalytes still form today in some places like
Shark Bay Australia. Being small forced the earlier life to be collaborative, being
simple forced it to become networked. Being limited forced it to become
something entirely new. Modern organisms are descendants of this networked
stage, but they have lost most of the collaborative abilities their ancestors
had. We have traded network intelligence for individual complexity, horizontal
sharing for vertical inheritance, collective adaptation for competitive
evolution, but traces of the ancient network still exist.
For decades what puzzled the scientists was how
random chemical reaction could give rise to the genetic code, the universal
language that translates RNA sequences into proteins. What the scientists
discovered recently changes what we thought about the origins of the genetic
code. In research published in 2024 it was found that information processing does
not evolve gradually from random chemistry. It appears suddenly through a process
they call informational phase transformation.
Below a certain threshold of molecular
complexity RNA sequences behave like ordinary chemicals reacting randomly with
the environment. But above that threshold they begin to exhibit properties we
associate with information; Pattern recognition, error correction, selective
replication. The transition happens at exactly 12 Nucleotides. RNA sequences
shorter than 12 bases remain purely chemical. Sequences of 12 or more
nucleotides can form stable secondary structures that give them specific
repeatable functions. This is the minimum length needed for an RNA molecule to
fold into a shape that can catalyse its own replication.
At below 12 Nucleotides RNA is just Chemistry,
but at 12 Nucleotides and above it becomes information. Work by scientists now
indicates that information processing might be an inevitable outcome of certain
type of chemical networks. When you have a system of enough components, enough
connections and enough energy flow informational properties emerge
automatically. Not through design, not through selection but as a direct
consequence of the systems organization. This is called Autocatalytic
emergence.
The chemistry creates conditions
that favour information processing, and information processing creates
chemistry that becomes more organized. It is a feedback loop that drives
increasing complexity without any external guidance.
Labs around the world are
creating artificial chemical networks that spontaneously develop informational
properties. These systems are not designed to process information. They are
just mixtures of organic molecules.
Dr Lee Cronin of the University
of Glasgow has built chemical computers using nothing but organic reactions in
solution. No DNA, no Proteins, no biological components at all. Just carbon
based chemistry that has learned to perform computational operations. They are
doing computation, but their computer is made of ordinary chemistry rather than
silicon and electrons.
Remarkably, these chemical
computers can evolve, introduce random mutations into the reaction networks,
and the systems develop new computational abilities over time. Not only are
they processing information, they are learning to process information more
effectively. This suggests that the
transition from chemistry to information processing is not a rare unlikely
event that happened once in Earth’s history.
Metabolism is the life’s solution
to the Universes’s most fundamental problem. The 2nd law of
Thermodynamics guarantees that all organized systems will eventually decay into
random heat and disorder. Yet everything on Earth somehow builds and maintains
complex molecular structures that become more organized over time and not less.
This is not a violation of the law of Thermodynamics but it requires something
remarkable, a continuous flow of energy that can be captured transformed and
used to drive chemical reactions uphill against their natural tendency.
Mitohondria in your cells use
Oxygen to extract energy from Glucose through a chain of precisely orchestrated
reactions. Chloroplastin plants capture light and use to build sugar molecules
from carbon dioxide. These systems are incredibly complex involving hundreds of
different enzymes working in
perfect coordination.
