Transcript Carbon - Tata Institute of Fundamental Research

7 sisters and
Intelligent life in the Universe
Mayank Vahia
Tata Institute of Fundamental Research, Mumbai
The seven sisters
• Recently a group in Belgium has found seven planets near a cool dwarf star.
• The star is 40 light years away.
• It was discovered by Belgian led TRAPPIST project (Transiting Planets and
Planetesimals Small Telescope)
• The team used NASA’s Spitzer Space Telescope along with ESO’s Very
Large Telescope in Chile and others in Morocco, Hawaii, Spain, and South
Africa.
• A final, nearly continuous 20-day observation with Spitzer in September
2016, during which the team saw 34 transits, allowed them to untangle the
mess. “Spitzer made all the difference
• They found 7 planets.
• all seven could conceivably harbour liquid water on their surfaces
• The orbits are in resonance i.e. their orbits are in integer numeric ratios and
this is not natural.
• Two innermost planets has a thick envelope of hydrogen gas.
• Tightly packed group of planets with orbits ranging from 1.5 to 12.3 days.
JULIANNE MOSES, 2 JANUARY 2014 | VOL 505 | NATURE | 31
History of Solar System
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http://library.thinkquest.org/C003763/images/planet/habzone.gif
However, planets do have more tricks up their sleeve and this may
permit life beyond the habitable zone
Habitable zone around a star
Habitable zone around a star has to be:
• Planet with a correct mixture of internal heat and stellar
radiation.
• Should support liquid water.
• It cannot get so hot as to photo dissociate water. This gives a
proximity limit of 0.95 AU for a liveable planet around our Sun
• The outer edge is defined by CO2 condensation temperature
which will shut down the carbon cycle. This gives a maximum
distance of 1.37 AU for a liveable planet around Sun.
www.sciencemag.org SCIENCE VOL 344 18 APRIL
2014 279
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www.sciencemag.org SCIENCE VOL 344 18 APRIL 2014 249
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51 Pegasi b (artist's conception) is the first exoplanet from which astronomers have detected visible reflected starlight; A&A April
2015
Image shows a face-on millimetre-wave view of the protoplanetary disk around the young star HL Tau (located at the bright central blob but not detected in this image). The dotted circles represent the locations of
emission dips (dark regions) where water
1 ice, frozen ammonia hydrates and clathrate hydrates are expected to condense. Combining such images, which can directly probe the disk's d ust and ice content, with spectral-line
observations such as those presented by Öberg et al. for the disk around the young star MWC 480, which selectively probe the gas and ice reservoirs of the disk,8will provide insights into the evolution of water and organic chemistry during planet formation. 1 AU is the distance from Earth to
the Sun. (Image created by K. Zhang in G. A. Blake's research group, from public-domain commissioning and science verification data from the ALMA observatory .) Planetary science: Prebiotic chemistry on the rocks Geoffrey A. Blake & Edwin A. Bergin Nature 520, 161–162 (09 April
2015)
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~100 pc away
Forbidden planets: Understanding alien worlds
once thought impossible
http://www.sciencemag.org/news/2016/07/forbidden-planets-understanding-alien-worlds-oncethought-impossible
By Daniel CleryJul. 28, 2016 , 2:00 PM
What is life?
We find it easier to define life by what it is not!
We assume life does the following:
1)
2)
3)
4)
It consumes food
It reacts to its environment in a complex manner
It grows and self-replicates
It produces a large number of chemical reactions
At the core of life is a-periodic complexity and not order.
A more accurate definition would be: A living objects is a region of order which
uses energy to maintain its organisation against the disruptive force of entropy!
LIFE CONSISTS OF MOLECULES THAT KNOW
• WHAT THEY LOOK LIKE
• HOW TO MAKE A COPY OF THEMSELVES
Carbon of life
• It seems that where ever the life is found, it will be carbon based. This is
because:
– Carbon is best suited for living molecules because:
• Accepts acidic and basic of atoms in reactions.
• Forms closed and open chains of chemicals with reversible reactions.
• Easily available in the Universe.
– Water, a unique liquid that is:
•
•
•
•
•
Chemically a simple molecule.
An excellent solvent.
Remains liquid over a wide range of temperatures and pressure.
It has the ‘triple point’ advantage.
It has high specific heat and high vapour pressure.
– Silicon can form long molecules has none of these advantages.
• However, such a life form need not be oxygen breathing or biped.
Process of creation of life
Random
Arrangement
TONFOMSIHIINSRIAT
________________
___________________
Crystal
structure
(ordered
system)
Most
common
Carbon
FINTH IT SSIMARINO O
Can occur
naturally
(e.g. by removing
thermal energy)
___________________
________________
Random
Complex
System
FN THTIISSI MARIOON
_____________
Information
containing
system
Can be created
by feeding
energy e.g.
inside living
systems
_____________________
THIS IS INFORMATION
We know no
way of
creating this!
Needs addition of
Configurational
energy
Recent Results - 1
• Simulations of comet impact have been done using
high power lasers.
• They showed that energetic reactions in high
pressure environment can significantly modify the
environment of a planet.
• Extraterrestrial impacts, can not only destroy the
existing ancient life forms, but also contribute to the
creation of biogenic molecules take organic matter
and bind it into living molecules.
High-energy chemistry of formamide: A unified mechanism of nucleobase formation
Martin Ferusa et al. 2015, PNAS www.pnas.org/cgi/doi/10.1073/pnas.1412072111A
Recent results - 2
• Scientists have recently identified a possible
mechanism by which nature may accumulate large
molecules.
• They have shown that a heat flux across an open
pore in submerged rock concentrates replicating
oligonucleotides (short, single-stranded DNA or RNA
molecules) from a constant feeding flow and selects
for longer strands.
Heat flux across an open pore enables the continuous replication and selection of oligonucleotides towards increasing length
Moritz Kreysing†‡, Lorenz Keil‡, Simon Lanzmich‡ and Dieter Braun*, Nature Genetics, Jan 2015
Recent Results -3
• Several comets and meteors show complex carbon
compounds.
• These objects must have been formed far away from
where the Earth is.
• Otherwise the volatile elements would not have
formed.
• These can then be transported to Earth.
Comet 67P and Rosetta Mission
• Recently European Spacecraft Rosetta went into orbit around the comet
67P (Churyumov–Gerasimenko) and also put a lander on it.
• Results from this mission were published in January 2015.
• P67 also had non-volatile organic molecules: a complex mixture of various
types of carbon-hydrogen and/or oxygen-hydrogen chemical groups, with
little contribution of nitrogen-hydrogen groups.
• They indicate presence of high-volatility ices (CH4, CO, CO2,CH3OH, etc.),
along with water.
• Iron rich grains may also be existing on P67.
• These materials must have been readily available when the nucleus of 67P
was born in the protosolar nebula.
• This suggests 67P was born produced in a low-temperature environment
consistent with large distances from the Sun, such as the Kuiper belt region.
Comet 67P
Recent Results - 4
• During the early steps in the origin of life, small droplets could have formed
via the segregation of molecules from complex mixtures by phase
separation.
• Researchers have examined the behaviour of droplets in systems that are
maintained away from thermodynamic equilibrium.
• In these systems, droplets grow by the addition of droplet material generated
by chemical reactions.
• They find that chemically driven droplet growth can lead to shape
instabilities that trigger the division of droplets into two smaller daughters.
• Therefore, chemically active droplets can exhibit cycles of growth and
division that resemble the proliferation of living cells.
• Dividing active droplets could serve as a model for prebiotic protocells,
where chemical reactions in the droplet play the role of a prebiotic
metabolism.
• Droplets can become chemically active if the material of the
• droplet is produced and destroyed by chemical reactions.
Evolution of Intelligent life
• Taking life from simple self replicating
molecules is not a simple task. It requires:
– Transformation form molecule to a cell.
– For a cell to transform to multi-cellular being.
– Sexual form of reproduction to improve fitness.
– Need for evolution of intelligence as a survival
strategy.
– Technological advances beyond survival needs.
Long term habitability of Earth
• A large number of parameters had the correct combination of
values for Earth:
– Correct star:
• Small, 3rd generation of star
• Isolation of the star.
• Stability of the star.
– Correct configuration of the planet:
• Planet size and structure.
• Moon, Jupiter and other outer planets.
• Circular orbit and its tilt of the axis of rotation
• Complex geological upheavals to regenerate material.
– Coherent environment:
• Correct temperature range.
• Correct mixture of elements.
• Magnetic field and Ozone layer
• Can all this be found at other place?
Search for Intelligent life on
Habitable Planets
• Drake’s Equation: The probability of finding intelligent life is:
P = Pt Ps Pp Ph Pg PI Pe Pc Pi Pr Pd
Where
P = Total probability given by:
Pt = total number of stars in the galaxy (~1011)
Ps = percentage of stars that can have planets (~20% late type only)
Pp = percentage of star that actually have planets (~80%)
Ph = percentage of stars with habitable zones (~10%)
Pg = percentage of planets with stable circular orbits
PI = percentage of planets where life has evolved
Pe = percentage of planets where life has moved beyond simple molecules
Pc= percentage of planets where life has moved to multi-cellular structure
Pi = percentage of planets that have intelligent life
Pr = percentage of life that avoided self-destruction
Pd = duration before which they emit detectable signals to earth
No of living planets
A wild guess
Earth
Level of Intelligence
What if there is intelligent life
• Contacting them will not be
easy because of vast
distances. So signals take long
time to travel AND become
fainter as the square of the
distance.
• Travelling will certainly not be
easy as long as we cannot find
a way around Relativity.
• The near habitable planet we
know is about 20 light years
away.
Interplanetary transport typically takes
10,000 times more time to reach a place than
light. i.e. 1 years to 10,000 years. 20 light
years is 2 lakh years – In comparison,
human civilisation has been on earth for 1
lakh years.
Some ideas on intelligent life elsewhere
• How many manage to overcome the ‘Nuclear barrier’?
• How many avoid pollution and resultant self-destruction?
• How many are not on stable planets in terms of planet quakes and meteor
showers?
• If advanced, how many are keen on exploration?
• If they are keen on exploration, are they violent?
• Maybe some will notice our ‘radio activity’ and will come towards us in
future. If they come,
– Will they come in person?
– Will they send their robots?
– Will they send their atom bombs, just to ‘evict’ us from this beautiful and
habitable planet?
Some have argued that the very fact that we have not had ‘visits’ interstellar
travelling super-intelligent life forms don’t exist, then of course there are
those who believe in UFOs.
Thank you