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Life in the Universe Heinz Oberhummer Vienna University of Technology Contents 1. Astrobiology 2. Characteristics of Life 3. Finding signs for extraterrestrial life – PowerPoint PPT presentation

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Title: Life%20in%20the%20Universe%20Heinz%20Oberhummer%20Vienna%20University%20of%20Technology


1
Life 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
2
Astrobiology
  • 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.


3
Characteristics 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

4
Characteristics 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
5
Characteristics 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
6
Characteristics of Life(as we know it)
  • Reproduction
  • All living organisms reproduce, either by sexual
    or asexual means.

Two daughter cells containing identical genetic
material
7
Characteristics 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
8
Characteristics 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
9
Life 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.

10
Life 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.

11
Life 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
12
Life 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.

13
Life 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.
14
Finding 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.

15
Finding 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.

16
Finding 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.

17
The production of carbon and oxygen
The production of carbon and oxygen in the
interior of Red Giants
18
Tripel-alpha process
The triple-alpha process in Red Giants
19
A remarkable prediction
Sir Fred Hoyle (1915 - 2001)
20
Reaction mechanism of triple-alpha process
21
A tailor-made Universe
22
The 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)?

23
Matter 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.

24
Matter and antimatter
25
The unification of the fundamental forces
A Theory of Everything should explain all
structures and processes in the Universe
26
Multiverse
  • 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
27
Theory of Everything or Multiverse?
28
Possible 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.                          

29
The triple-alpha process 850 years ago
Fountain chapel of the monastery Maulbronn,
Deutschland.
30
BooksJ. 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
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