Title: Life%20in%20the%20Universe%20Heinz%20Oberhummer%20Vienna%20University%20of%20Technology
1Life in the UniverseHeinz OberhummerVienna
University of Technology
Contents 1. Astrobiology 2. Characteristics of
Life 3. Finding signs for extraterrestrial life
4. Preconditions for Life 5. Cosmological
fine-tuning
2Astrobiology
- Astrobiology is a new scientific,
interdisciplinary field of all living things
within the universe, where they might be found
and how they were formed. - The central questions of astrobiology Are we
alone? Is the Earth unique in its ability to
create and sustain life? - Astrobiology has emerged in the last 10 years
from speculations to investigations because of
suggestive new findings in several scientific
fields.
3Characteristics of Life(as we know it)
- A universal definition of life is at present not
possible. There are different definitions
characteristic for life - Structure and boundary
- Energy
- Reproduction
- Adaptation
- Information
4Characteristics of Life(as we know it)
- Structure and boundary Carbon-based life is
made out of cells, the basic unit of life.
An amoeba is a single cell-organism
5Characteristics of Life(as we know it)
- Energy Living organisms require energy, usually
in the form of ATP (adenosine triphosphate). They
use this energy to carry out energy-requiring
activities such as metabolism and locomotion.
Molecular model of ATP, the energy carrier of
cells
6Characteristics of Life(as we know it)
- Reproduction
- All living organisms reproduce, either by sexual
or asexual means.
Two daughter cells containing identical genetic
material
7Characteristics of Life(as we know it)
- Adaptation All living things respond to stimuli
in their environment.
Pore (stomata) of a leaf opening in response
to light stimulus
8Characteristics of Life(as we know it)
- Information All living things carry information
as a biological blueprint. In carbon-based life
this information is stored in the DNA
(deoxyribonucleic acid).
Schematic view of the double helices of the DNA
molecule
9Life on Earth
- Biological evolution is the theory that explains
the origin of all the diverse life forms on Earth
(in other words, the origin of species). There
are millions of different organisms on Earth,
ranging from microscopic bacteria to elephants. - The theory of evolution states that all these
different kinds of living things evolved from
common ancestors over a time span of billions of
years since the first appearance of life on
Earth.
10Life on Earth
- Life on Earth is the only example that we know
and have ever examined. - Life on Earth is carbon-based and water-based.
Carbon is by far the most manifold element in
forming complex structures (molecules). Water is
a unique and unusual liquid that is optimal for
carbon-based life in many respects.
11Life on Earth
- Carbon is the most appropriate element in
forming complex structures (molecules). There
exist f. i. more carbon molecules (organic
chemistry) than all other molecules (inorganic
chemistry).
2,4,4-trimethyl hexane
12Life on Earth
- Water is an unique and unusual liquid with
properties that makes it optimal for carbon-based
life Solvent, heat capacity, density, etc. - Lawrence J. Henderson, The Fitness of the
Environment, New York 1913 Water, of its very
nature, as it occurs automatically in the process
of comic evolution, is fit, with a fitness no
less marvellous and varied than that fitness of
the organism which has been on by the process of
adaptation in the course of organic evolution.
13Life on Earth
- Terrestrial life can also be found in extreme
environments Interior of nuclear reactors,
ice-covered Antarctic lakes, sub-oceanic
hydrothermal vents, deep sub-surface rocks.
The giant tube worm lives around hydrothermal
vents, where temperatures exceed 700 degrees.
Scientists once believed that no living thing
could survive the combination of toxic chemicals,
high temperatures, high pressures, and total
darkness at these vents.
14Finding signs for extraterrestrial lifewithin
the Solar System
- Finding life within the Solar System is arguably
easier than looking outside. Since we are
presently not able to mount expeditions to other
stars for decades, the only way we can directly
look for life is by sending probes to nearby
planets and moons such as Mars, or the moons
Europa and Titan. - These probes have an immense advantage in that
they can examine the surface of these planets in
detail and detect primitive life such as
micro-organisms that would be almost impossible
for us to detect on other stars.
15Finding signs for extraterrestrial lifeoutside
the Solar System
- Disregarding interstellar travel for the moment,
another way you can look for life outside our
solar system is by sending out, and listening to,
radio or laser transmissions (like SETI).
However, this assumes that the life you are
trying to contact is a) listening, b) interested
in communication and c) intelligent enough to
communicate. - Now, you might think that pretty much all
extra-terrestrial life would fulfil each one of
those clauses. But when you think about it,
humans themselves have only been around for
roughly 150,000 years. It's only been the last
few decades that we've fulfilled those clauses.
16Finding signs for extraterrestrial lifeoutside
the Solar System
- There are also possibilities in the 21st century
for the remote detection of life on Earth-like
extrasolar planets through indirect searches by
detecting in the visible of atmospheric gases
related to life processes. Such a search would
look for signs of the large-scale effects that
life would have on a planets chemistry. - By analyzing the colours of infrared radiation,
astronomers can search for atmospheric gases such
as ozone, carbon dioxide or water vapour in
appropriate quantities. Together with the
temperature and radius of the detected planets,
this information will allow astronomers to
determine which planets are habitable, or even
whether they may be even inhabited by rudimentary
forms of life.
17The production of carbon and oxygen
The production of carbon and oxygen in the
interior of Red Giants
18Tripel-alpha process
The triple-alpha process in Red Giants
19A remarkable prediction
Sir Fred Hoyle (1915 - 2001)
20Reaction mechanism of triple-alpha process
21A tailor-made Universe
22The Cambridge meeting
- From August, 29th to September 1st, 2001 about
30 cosmologists, astro-physicists, nuclear and
particle physicists met at the Univ. Cambridge. - The objective of this meeting was to discuss the
fine-tuning of our universe for the existence of
life. -
- Two main questions were discussed1. How
fine-tuned is our universe for the existence of
life?2. Can the fine-tuning of our universe be
explained from a final Theory of Everything? Or
is the alternative model correct that our
universe is just one of an ensemble (multiverse)?
23Matter and antimatter
- The amount of matter and antimatter is almost the
same. Only the small asymmetry of one billionth
more matter than antimatter exists in our
Universe. - All the antimatter was annihilated with the same
amount of matter already during the first
fraction of a second after the Big Bang. Only the
tiny surplus of matter make up the stars, planets
and life in our Universe. - If the amount of matter would have been exactly
the same as the amount of anti-matter all matter
would have annihilated with the antimatter. Our
Universe would then consist only of boring
radiation without any structure and life. - However, also with only a tiny surplus of more or
less matter (a factor of 10-15!) as in our
Universe no life would have developed. - A little more matter In this case the additional
gravitational force would accumulate again in a
short time to the Big Crunch. The time for the
formation of stars would be much too short. - A little less matter The expansion would be so
rapid that no stars could form. Therefore, again
life would not be possible.
24Matter and antimatter
25The unification of the fundamental forces
A Theory of Everything should explain all
structures and processes in the Universe
26Multiverse
- The model of the chaotic self-replicating
eternal inflation has the consequence that not
only different regions of the universe exist, but
such regions can also be created eternally
(multiverse). The inflated regions (blue regions)
expand much faster than the thermalised regions
(red regions). - Our region of the universe is pre-conditioned
for carbon-based life, whereas many other regions
with only slightly different fundamental
parameters are probably sterile.
Inflationary
Thermalised
27Theory of Everything or Multiverse?
28Possible explanations of cosmological fine-tuning
- Hypothesis of chance The Universe is just like
it is and needs no further explanation. - Hypothesis of logical necessity It must have
been like that, because otherwise we would not be
here. - A tailor-made Universe There exists a final
Theory of Everything explaining cosmological
fine-tuning. We just dont know it yet. - Multiverse model There exist an infinite number
of universes. We live in a universe that is
live-friendly, whereas most other universee are
sterile. - Theistic explanation There exists a
Designer.
29The triple-alpha process 850 years ago
Fountain chapel of the monastery Maulbronn,
Deutschland.
30BooksJ. Darling, Life Everywhere, Basic Books,
2001B. Jakosky, The search for life on other
planets, 1998M. Rees, Our Cosmic Habitat,
Phoenix mass market, 2003G. Zubay, Origins of
Life on the Earth and in the Cosmos, Academic
Press, 2000WebsitesAstrobiology, the living
universehttp//www.ibiblio.org/astrobiology/Euro
pean Exo/Astrobiology Network Associations
(EANA)http//www.graz-astrobiology.oeaw.ac.atLIU
. Life in the Universehttp//www.lifeinuniverse.o
rgNASA Astrobiology Institutehttp//nai.arc.nasa
.gov NASA Astrobiology Roadmaphttp//astrobiolog
y.arc.nasa.gov.roadmapAlone? A Discovery
Sourcebook on Astrobiology, ISU Design Team,
2002http//www.isunet.edu/library/SSP_design_proj
ects.htm
Literature