Is there life outside earth?
The famous American designer, architect and futurist Buckminster Fuller once said “Either
we are alone in Universe or we are not. Either way the implications are
staggering”.
At least from the time human beings became aware that there are worlds
outside earth they are confronted with this fundamental and profound question.
Answer to this question beyond doubt has not been found yet, but we are in an age
where we will be beginning to get it.
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| Evolution of science |
There are a few primary conditions for life to evolve.
The first condition is existence of other planets other than earth in the solar system and away from our own solar system. We know that planets evolve from the gas and dust surrounding a star due to radiation. The gas and dust slowly accrete to asteroids and then planets itself due to gravitation. It is now known from scientific observation that is a common and often repeated process in this universe. Although some new data suggests that this may not be the only way planets can form. From the recent data we can say that there is almost uncountable number of planets in cosmos.
The first condition is existence of other planets other than earth in the solar system and away from our own solar system. We know that planets evolve from the gas and dust surrounding a star due to radiation. The gas and dust slowly accrete to asteroids and then planets itself due to gravitation. It is now known from scientific observation that is a common and often repeated process in this universe. Although some new data suggests that this may not be the only way planets can form. From the recent data we can say that there is almost uncountable number of planets in cosmos.
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| Formation of planets
Secondly, for life to evolve as we know in our earth there must be
carbon and water in that planet. As we now know both of these are abundantly
available in universe. Carbon is created by nuclear fusion inside a star. Many
stars die with a huge explosion (called supernovas) and carbon created from
them are scattered in the interstellar space. The carbon that has reached earth
has a history of birth and of many many stars. We are mostly composed of carbon
and the history of each carbon atom is different, they were born inside
different millions and billions of stars. The universe was created roughly 13.7
billion years ago with a big bang ( although we cannot say that this theory is
proved beyond doubt).However as more time has passed from creation of this
universe there have been birth and death of more stars and therefore more
carbon atoms have born. Therefore this universe has become progressively more fit
for life with age. The life as we know in earth has the definition of same
genetic code or DNA. Without this cells cannot divide and reproduce itself
which is the definition of life.
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Abundance of carbon in cosmos
But when we are talking about life outside earth we must remember that
there can be life whose chief elements may not be carbon and water. Although we
do not know there perhaps can be life without carbon and water. Secondly carbon
may be able create such fundamental element of life which is not DNA. We also
must consider a third possibility. The power and artificial intelligence of
computers and robots run by computers are increasing at a tremendous rate. The
power of smart phones which we use in our pockets for everyday purpose is 50
times more than the first computer ENIAC built in 1946. ENIAC was as big as a
large size apartment (1800 square feet or 167 square meters). According to the
Moore’s Law the intelligence of computers and robots will be equal to the
humans within next 20-30 years (this 2013).There is a high possibility that
those computers and robots will act like a living creature and will reproduce
like a living creature. Therefore these robots will also be called living
beings. When we consider life in cosmos we must remember these possibilities.
ENIAC
Life has earth has evolved within a relatively short time (1 billion
years) after birth of earth (4.6 billion years). At this point of time the
atmosphere of earth was highly hostile for life. Different highly toxic gases,
high volcanic activity, and intensely frequent impacts from outer space were
big deterrent to life. But in spite of all of these life came early in earth.
Secondly, as I said earlier, that the chief ingredients for life,
carbon and water, are abundantly available in cosmos.
Thirdly it is observed that life evolves easily when the chief
ingredients of life are available together. We do not know the total process of
making of life entirely. We do not know whether life cells will ever be
generated in laboratory totally, however, we do know that the fundamental
ingredients of life very easily combine with each other to produce life.
Fourthly, it has been observed that life is created almost in any
natural condition. We need a rather mild
condition to live, that is, humans cannot live in very high or low pressures or
temperature and pressure or in hostile natural conditions. We also need
sunlight for our existence. But there are many species on earth, especially microbes,
which can withstand much more extreme conditions. Microbes are found where rain
has not fallen for last 100 years, there are tremendously toxic elements, the
pressures are too high (1000 times), where there is very high level of nuclear
radiation and where no sunlight ever reaches. So life can evolve in conditions
in much more hostile conditions than we can imagine.
 
Life in extreme cold
Life in extreme toxicity
Life in extreme radiation
Life in extreme isolation
Lastly as per latest estimates the number of places in cosmos where life can evolve (including life like human beings) are almost innumerable.
So every ingredient and condition for life to be created is present in
the universe we know.
Probability of life in universe
Now let us see whether we can find any glimpse of life in our own solar
system. The planet which tantalizes us most is of course Mars. From
observations of telescopes and space missions to Mars we know that its surface
is a desert. At some point of time, 2-3 billion years ago, there was water in
its surface which has since evaporated. Therefore if there is life in Mars it
is in form of microbes beneath its surface. But we have observed something in
Mars which has great implications. It is clear from the photographs taken of
Mars that from beneath sprouts to the surface in considerable quantities even
now. So there is obviously water below the surface of mars. How much below, 5,
10, 15 or 100 meters, we do not know. All the robots those have been sent to
mars till now only can scratch the surface, so at this point of time we cannot
search for life in mars to a great extent. But in near future space missions to
mars will explore it much deeper. Within 2020 mars will be crowded by human
space missions and extensive researches will happen. So we can hope that we
will know about life in mars within next decade.
Evidence of water in Mars
The next place that catches our attention is the big satellite of
Jupiter, Europa (Europa is visible even with a small telescope). The surface of Europa is covered with 500 to
1 kilometer thick ice. But beneath it is many kilometer deep ocean of liquid
water. This water is slightly warm by the heat from the interior of the
satellite, although it is still very cold. However it is not so cold that life
cannot exist here. We are getting to know a lot of places which are very cold
as it are but life is possible there. NASA has a plan to explore the interior
of Europa with the help of nuclear energy.
Surface of Europa
Interior of Europa
Another very exciting place is Titan, satellite of Saturn. There are
intriguing similarities between surface of Titan and earth. There is not only
liquid on the surface of titan but full rivers and lakes. Although those rivers
and lakes are made of liquid methane and ethane. There are active volcanoes
here. It has an atmosphere which is full of nitrogen, a chief component of
atmosphere of earth. It is not impossible that the chemistry of methane,
ethane, ammonia and water (which is beneath the surface) has created some
exotic form of life here. NASA has plans for going to Titan also but that is at
least a decade away from now.
Lacus Ontario of Titan
There is also this small satellite of Saturn, Enceladus. The diameter
of Enceladus is only 500 kilometer. But water and salt is sprouting out from
beneath its surface through geysers. Water is here also below the surface.
Enceladus
If we only think of the fundamental ingredients of life, that is,
liquid water, organic molecules and required heat and energy then there are a
dozen of places inside our solar system, counting planets and moons of planets.
It is not at all impossible that at least microbes exist in a few of these
places.
In 1995 scientists first found planets outside our solar system. The
planet is in the constellation of Pegasus and it is revolving around a star
named Pegasi 51.From this time onwards new planets were found quite regularly.
In 2009 NASA sent a space observatory Kepler which can find planets much more
precision in a specific part of the sky. Let me explain a bit how planets
outside our solar system are found. The amount of light from the planets are so
small compared to the luminosity of stars that it is not possible to catch it
with our present telescopes and indirect methods are applied. Stars wobble due
to the gravitational pull of planets. Also when the planets cross the equatorial
plane of the star then there is an eclipse of the star due to the planet. By
calculating the wobble of the star and how much light is reduced during the
eclipse one can get the mass and volume of the planet. From that we get the
density of it. From the density of the planet one can calculate what material
it is made of.
Kepler spacecraft
Less light from star during eclipse at Kepler's observation
(in the graph below) from which we know about planets
The first planets those were found were giant gaseous planets like
Jupiter. Although there may not be life in those the satellites of these
planets may harbor life. With the development of technology and precision of
observation much smaller and almost all sorts of planets (expected and
unexpected) are being found. Planets made of almost totally liquid water, made
of metals and also made of mixture of metals and water are all found. By computer
modeling it has been found that in the solar system of a sun like star there
2-5 planets made of rock and water (like earth) and out of those 10-20% are in
a habitable zone (that is habitable for living beings in earth). How far away
is the habitable zone is from the star depends on the temperature and
luminosity of the star. Some people call this habitable zone as Goldilock Zone.
Computer modeling also tells us that earth like planets which are made of water
and rock is not all rare but quite abundant. Now let us see what observations
from Kepler tells us. Until July 2013 Kepler has found 134 confirmed and 3277
unconfirmed (till now) and 76 other solar systems. It is expected that 90% of
the unconfirmed planets are actually planets (it will take a little time to
confirm them). One must remember that Kepler has searched for planets within
only a limited portion of the sky. The big news is two planets, 1200 light
years away (named Kepler 62E and 62F), were found which are most probably made
of water and rock like earth and also are in Goldilock zone. Even the star when
viewed from the planet looks like our sun. Scientists are of the opinion that
it is a big step forward. The most important thing is from the data sent by
Kepler (by the research on the data till now) it is estimated that there are
100 billion planets like earth which are habitable in our Milkyway galaxy
itself. Since we know there are 500 billion galaxies in visible universe, so
the number of planets fit for life in the universe we know are almost
unimaginable.
Until now we have tried to know whether there are any other earthlike (constituent
and habitability wise) planets elsewhere. This endeavor will continue. But how
will we know whether there are actually life in them? The planets are so far
away (many light years away) that it will be impossible for us in near or
remote future to go to them. But what can be done and soon we will do is to
analyze the light from those planets through huge telescopes and see whether
the atmosphere of those planets contain the ingredients which should be there
if there is life. These ingredients are ozone, water, oxygen, methane etc. If
there is no life then the possibility of these elements to be present in the
atmosphere, particularly together, is miniscule for scientific reasons. So if
can detect these elements in the atmosphere we can deduce that there is life.
For this reason very big telescopes like VLT in Chile and LBT in Arizona have
just been built which can collect even very minute amount of light. These and
the James Webb telescope which will be sent to space in 2018 will carry out
this kind of research. So we can hope that as a result of this research we will
get an answer to the question whether there is life elsewhere in the next
decade.
James Webb space telescope
But we have to remember if we get Earth 2.0 it will not be exactly like
earth. Neither can we hope to go and colonize there if there is problem in
earth or for that matter for joy ride in near future. The reason is they will
be a few hundred or more light years away and we do not know when the science
and technology will come, or ever come.
Well this was a rough estimate of places where there can be life. But
what about advanced lives, who are as or even more intelligent than us, humans?
Are they there and if so in how many places?
To get an idea of it we have to do a list of how many intelligent life
are there in our earth. Although we do not think microbes as intelligent beings
their capacity is far more than we assume. Microbes are quite developed bio
factories and they can understand magnetic fields, can produce nano wires and
they have a communal capacity to anticipate the atmosphere and they can also
make friends with other species of microbes.
Things microbes can do
Next we come to various insects. Termites can build
structures which are huge compared to their own size. Some of the termite
mounds are bigger than biggest of sky scrapers we have built if we compare our
size and the size of termites
Termite mounds
In some insects the intelligence is distributed in the hive or colony
instead of within individuals. They have complex social behavior and they are
efficient in specific jobs. Also they can communicate with each other
chemically.
Ordinary insects
Among those which we call pets, parrots are very
playful and talkative, defines new words and can understand the concept of
zero. It has been seen that when a crow is a given food within a bottle and
something similar to a wire, it can take the food away from the bottle by
bending the wire. Rats are also quite complex. They can anticipate sexual
mating and they can reflect upon their own thoughts (meta cognition).
Rat and parrot
There are also beings of whose intelligence we know very little and we
cannot communicate with them. Like the sea living cephalopods (example
octopus). Their brains are distributed in their bodies and when one arm is
severed from the body it acts like a self sufficient creature. The divers have
found out some peculiar abilities of these creatures. These are aliens in our
own planet. If we want to know about aliens we have to know these far better.
Cephalopods
If we compare our brain mass with the body mass we
special but not very far above many others.
Comparison of brain and body mass of earthlings
Like the dolphins called orcas (which are known as
killer whale as well).They do not have any natural enemies except humans, the
brain mass compared to body is big and complex like humans, they talk with each
other in a very complex and developed language, they have their families and
societies, they nurture their offspring (up to a comparative age similar to
humans), they take life partners like marriage. although they do not have cell
phones and internets mostly perhaps because they do not have fingers and
neither do possess cars (which they do not need) or bombs which is not their
loss. Also they are supremely adapted to their environment.
Orcas
If we take a look at the increment of intelligence of living beings in
earth it has happened in a much accelerated way in last 2 million years and
particularly last 100,000 years. If we consider the increase in brain mass
compared to the body mass then we see that increase in brain mass compared to
the body of beings like humans have happened comparatively very recently and if
aliens came to this earth in last 50 million years they would have found the
dolphins and whales (or their ancestors) as the most brainy creatures in earth.
Evolution of intelligence
We can do a list of how many types of life is there. Firstly the cells
can be of many types. Secondly the slow change in life forms by natural
selection and mutation that we see in earth can be greatly enhanced by gene
swapping which can happen elsewhere. Also, although the life in earth is
composed of cells. it may not be necessary to have cells to do what life does.
There are things which are not cells but when connected to each other act like
cells. very small bio particles can act like living things by connected to each
through geo engineering, may be in a planetary scale.
Also there can be new forms of life by changing the genetic code. The
life we know in earth are composed of DNA, RNA, and protein. There can be life
forms which do not require all these. Information equivalent to information
inside a few DVDs are inside our genetic code the principles of bio chemistry
allows for even more compaction which will greatly enhance evolution. There can
be life which evolve without water and carbon. Also there can be life which we
will not recognize as life.
  
Possible different types of life elsewhere
Although life started in earth at around 3.6 billion years ago it is
the development of humans (a few 100.000 years ago) and then through
civilization and books (a few thousand years) that information sharing gathered
momentum. It has exploded in last few decades in digital age and the steep rise
in information sharing has made it to 1019 times than it originally
was. As I said earlier the intelligence of computers and robots will equal that
of humans within 20-30 years and although we may not go to other planets we
will be able to send these robots to them and even if we travel at one tenth
speed of light without breaking the barriers of relativity theory we will
colonize the Milkyway in 15 million years.
Colonization of our galaxy with help of robots
In 1950 the famous scientist Enrico Fermi said something very
interesting. he said that our civilization is very young and with the natural
evolution of it we will venture to other planets very soon. He thought of
imaginable uncountable habitable places and said that it is quite possible that
an exact replica is earth is somewhere there in which life has evolved 60
million years earlier. In that case the civilization there has that much head
start to us. To them we might be like anaerobic bacteria to us.
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Enrico Fermi
The answer to Fermi question can be many. 1) We are alone. Nowhere else
has civilization and technology evolved, our civilization is an accident. 2)
Civilizations like us are rare and too far away by apace and time. This cosmos
is a very big place; our own galaxy is a very big place. 3) They are there but
we do not have the capacity to recognize them. 4) They are there and they are
so much advanced compared to us that they have no interest in us. And lastly
the life in earth may be started by some of the aliens.
Answers to Fermi question
How can there be communication between earthlings and aliens? There is
this outlandish possibility that they are amongst us right now but we are not
recognizing them. If this is true then by logic you or can be an alien. But if
we for the moment discount this possibility then what we get? To get an idea of
number of places where civilization and technology like ours (or better) have
developed, a scientist named Frank Drake has developed an equation (called
Drake equation). It goes like this
N= R* . fp . ne . fl . fi .
fc . L
N = The number of advanced civilizations with whom communication is possible
R* = Average number of stars in our galaxy per year
fp = the fraction of these planets which have planets
ne = The fraction among these stars with planets in which
life is possible
fl = The fraction in which life have actually evolved among
those planets in which life is possible.
fc = The fraction among those lives which has developed such
technology that signals sent by them are possible to detect.
L = The amount of time these civilizations are sending these signals
The equation is very easily understandable and a gradually diminishing
number. I will only say a little about the last quantity L. It is possible that
the advanced civilizations may become extinct after some time (because of
things like nuclear bombs or heating up of planet due to green house gases). So
it is a matter of conjecture that even though advanced civilizations happen how
long they will last. The first three numbers in thus equation are already
determined or being determined through scientific data. Remaining numbers are
still totally a matter of personal guesswork.
Drake Equation
Among the spacecrafts sent by man a plaque containing some symbols in a
bottle in Pioneer 10 and a gramophone record in Voyager has been sent as
information about human civilization and technology. Both of these have left
our solar system and perhaps will reach some other civilization someday.
Picture sent in Pioneer 10
Gramophone record sent in Voyager
There has been an experiments going on for last 50 years or so to catch
signals from extraterrestrial civilization called Search for Extraterrestrial
Intelligence or SETI. It is made in such a way that signals in radio wavelength
as also optical pulse lasers from outer space can be detected as well as sent.
Although there has been silence for last 50 years the experiment is reaching an
exciting stage within next 20 years because at that time it will be possible to
detect signals from any planet within 3000 light years away (which numbers 100
million) as also we will be able to send signals to them. So there is a
possibility that we will connect with aliens in the lifetime of many living
now. But it must be remembered any civilization we will connect with must
necessarily be very close to ours because not in a very far future from now we
ourselves will not use radio signals or optical pulse lasers.
SETI
There is no guarantee that our connection with aliens will be a happy
experience because 1) they can ignore us, 2) they may think us as their prey
and attack us.
I will end this article with an example. the number of planets we know
of through Kepler is almost equal to a pinch of sand in our finger tips. The
number is around 3000. I have already told you that the possible number of
habitable worlds according to current estimate is around 100 billion in our
galaxy. Now if we consider 500 billion galaxies in the visible universe then
the number of habitable world will become equal to the number of sand particles
that is visible seating in a sea beach. Now it is your guess in how many of
them living beings are advanced enough that they are searching for life
elsewhere.
No of planets Kepler has detected
No of habitable planets in universe
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This article is inspired by a lecture of eminent cosmologist Professor Chris Impey of University of Arizona. Most of the data given are from his lecture which can be found in You Tube
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