A Statistical Estimation of the Occurrence of Extraterrestrial Intelligence in the Milky Way Galaxy
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Modelling Panspermia in the TRAPPIST-1 System
October 13, 2017 Modelling panspermia in the TRAPPIST-1 system James A. Blake1,2*, David J. Armstrong1,2, Dimitri Veras1,2 Abstract The recent ground-breaking discovery of seven temperate planets within the TRAPPIST-1 system has been hailed as a milestone in the development of exoplanetary science. Centred on an ultra-cool dwarf star, the planets all orbit within a sixth of the distance from Mercury to the Sun. This remarkably compact nature makes the system an ideal testbed for the modelling of rapid lithopanspermia, the idea that micro-organisms can be distributed throughout the Universe via fragments of rock ejected during a meteoric impact event. We perform N-body simulations to investigate the timescale and success-rate of lithopanspermia within TRAPPIST-1. In each simulation, test particles are ejected from one of the three planets thought to lie within the so-called ‘habitable zone’ of the star into a range of allowed orbits, constrained by the ejection velocity and coplanarity of the case in question. The irradiance received by the test particles is tracked throughout the simulation, allowing the overall radiant exposure to be calculated for each one at the close of its journey. A simultaneous in-depth review of space microbiological literature has enabled inferences to be made regarding the potential survivability of lithopanspermia in compact exoplanetary systems. 1Department of Physics, University of Warwick, Coventry, CV4 7AL 2Centre for Exoplanets and Habitability, University of Warwick, Coventry, CV4 7AL *Corresponding author: [email protected] Contents Universe, and can propagate from one location to another. This interpretation owes itself predominantly to the works of William 1 Introduction1 Thompson (Lord Kelvin) and Hermann von Helmholtz in the 1.1 Mechanisms for panspermia...............2 latter half of the 19th Century. -
Intelligent Design, Abiogenesis, and Learning from History: Dennis R
Author Exchange Intelligent Design, Abiogenesis, and Learning from History: Dennis R. Venema A Reply to Meyer Dennis R. Venema Weizsäcker’s book The World View of Physics is still keeping me very busy. It has again brought home to me quite clearly how wrong it is to use God as a stop-gap for the incompleteness of our knowledge. If in fact the frontiers of knowledge are being pushed back (and that is bound to be the case), then God is being pushed back with them, and is therefore continually in retreat. We are to find God in what we know, not in what we don’t know; God wants us to realize his presence, not in unsolved problems but in those that are solved. Dietrich Bonhoeffer1 am thankful for this opportunity to nature, is the result of intelligence. More- reply to Stephen Meyer’s criticisms over, this assertion is proffered as the I 2 of my review of his book Signature logical basis for inferring design for the in the Cell (hereafter Signature). Meyer’s origin of biological information: if infor- critiques of my review fall into two gen- mation only ever arises from intelli- eral categories. First, he claims I mistook gence, then the mere presence of Signature for an argument against bio- information demonstrates design. A few logical evolution, rendering several of examples from Signature make the point my arguments superfluous. Secondly, easily: Meyer asserts that I have failed to refute … historical scientists can show that his thesis by not providing a “causally a presently acting cause must have adequate alternative explanation” for the been present in the past because the origin of life in that the few relevant cri- proposed candidate is the only known tiques I do provide are “deeply flawed.” cause of the effect in question. -
Lecture-29 (PDF)
Life in the Universe Orin Harris and Greg Anderson Department of Physics & Astronomy Northeastern Illinois University Spring 2021 c 2012-2021 G. Anderson., O. Harris Universe: Past, Present & Future – slide 1 / 95 Overview Dating Rocks Life on Earth How Did Life Arise? Life in the Solar System Life Around Other Stars Interstellar Travel SETI Review c 2012-2021 G. Anderson., O. Harris Universe: Past, Present & Future – slide 2 / 95 Dating Rocks Zircon Dating Sedimentary Grand Canyon Life on Earth How Did Life Arise? Life in the Solar System Life Around Dating Rocks Other Stars Interstellar Travel SETI Review c 2012-2021 G. Anderson., O. Harris Universe: Past, Present & Future – slide 3 / 95 Zircon Dating Zircon, (ZrSiO4), minerals incorporate trace amounts of uranium but reject lead. Naturally occuring uranium: • U-238: 99.27% • U-235: 0.72% Decay chains: • 238U −→ 206Pb, τ =4.47 Gyrs. • 235U −→ 207Pb, τ = 704 Myrs. 1956, Clair Camron Patterson dated the Canyon Diablo meteorite: τ =4.55 Gyrs. c 2012-2021 G. Anderson., O. Harris Universe: Past, Present & Future – slide 4 / 95 Dating Sedimentary Rocks • Relative ages: Deeper layers were deposited earlier • Absolute ages: Decay of radioactive isotopes old (deposited last) oldest (depositedolder first) c 2012-2021 G. Anderson., O. Harris Universe: Past, Present & Future – slide 5 / 95 Grand Canyon: Earth History from 200 million - 2 billion yrs ago. Dating Rocks Life on Earth Earth History Timeline Late Heavy Bombardment Hadean Shark Bay Stromatolites Cyanobacteria Q: Earliest Fossils? Life on Earth O2 History Q: Life on Earth How Did Life Arise? Life in the Solar System Life Around Other Stars Interstellar Travel SETI Review c 2012-2021 G. -
Set 4: Active Galaxies
Set 4: Active Galaxies Phenomenology • History: Seyfert in the 1920’s reported that a small fraction (few tenths of a percent) of galaxies have bright nuclei with broad emission lines. 90% are in spiral galaxies • Seyfert galaxies categorized as 1 if emission lines of HI, HeI and HeII are very broad - Doppler broadening of 1000-5000 km/s and narrower forbidden lines of ∼ 500km/s. Variable. Seyfert 2 if all lines are ∼ 500km/s. Not variable. • Both show a featureless continuum, for Seyfert 1 often more luminous than the whole galaxy • Seyferts are part of a class of galaxies with active galactic nuclei (AGN) • Radio galaxies mainly found in ellipticals - also broad and narrow line - extremely bright in the radio - often with extended lobes connected to center by jets of ∼ 50kpc in extent Radio Galaxy 3C31, NGC 383 Phenomenology • Quasars discovered in 1960 by Matthews and Sandage are extremely distant, quasi-starlike, with broad emission lines. Faint fuzzy halo reveals the parent galaxy of extremely luminous object 38−41 11−14 - visible luminosity L ∼ 10 W or ∼ 10 L • Quasars can be both radio loud (QSR) and quiet (QSO) • Blazars (BL Lac) highly variable AGN with high degree of polarization, mostly in ellipticals • ULIRGs - ultra luminous infrared galaxies - possibly dust enshrouded AGN (alternately may be starburst) • LINERS - similar to Seyfert 2 but low ionization nuclear emission line region - low luminosity AGN with strong emission lines of low ionization species Spectrum . • AGN share a basic general form for their continuum emission • Flat broken power law continuum - specific flux −α Fν / ν . -
6 Dynamical Generalizations of the Drake Equation: the Linear and Non-Linear Theories
6 Dynamical Generalizations of the Drake Equation: The Linear and Non-linear Theories Alexander D. Panov Abstract The Drake equation pertains to the essentially equilibrium situation in a popu- lation of communicative civilizations of the Galaxy, but it does not describe dynamical processes which can occur in it. Both linear and non-linear dynam- ical population analyses are built out and discussed instead of the Drake equa- tion. Keywords: SETI, the Drake equation, linear population analysis, non-linear population analysis. Introduction Communicative civilizations (CCs) are the ones which tend to send messages to other civilizations and are able to receive and analyze messages from other civili- zations. The crucial question of the SETI problem is how far the nearest CC from us is. Its answer depends on the number of CCs existing in the Galaxy at present. Fig. 1 shows how the distance between the Sun and the nearest CC depends on the number of CCs in the Galaxy. The calculation was made by us by the Monte Carlo method with the use of a realistic model of the distribution of stars in the Galaxy (Allen 1973) and the actual location of the Sun in the Galaxy (8.5 kpc from the center of the Galaxy). The best known way to answer the question about the number of CCs is the formula by F. Drake N R f n f f f L C * p e l i c , (Eq. 1) where R∗ is a star-formation rate in the Galaxy averaged with respect to all time of its existence, fp is the part of stars with planet systems, nе is the average number of planets in systems suitable for life, fl is the part of planet on which life did appear, fi is the part of planets on which intelligent forms of life devel- oped, fc is the part of planets on which life reached the communicative phase, L is the average duration of the communicative phase. -
Bayesian Analysis of the Astrobiological Implications of Life's
Bayesian analysis of the astrobiological implications of life's early emergence on Earth David S. Spiegel ∗ y, Edwin L. Turner y z ∗Institute for Advanced Study, Princeton, NJ 08540,yDept. of Astrophysical Sciences, Princeton Univ., Princeton, NJ 08544, USA, and zInstitute for the Physics and Mathematics of the Universe, The Univ. of Tokyo, Kashiwa 227-8568, Japan Submitted to Proceedings of the National Academy of Sciences of the United States of America Life arose on Earth sometime in the first few hundred million years Any inferences about the probability of life arising (given after the young planet had cooled to the point that it could support the conditions present on the early Earth) must be informed water-based organisms on its surface. The early emergence of life by how long it took for the first living creatures to evolve. By on Earth has been taken as evidence that the probability of abiogen- definition, improbable events generally happen infrequently. esis is high, if starting from young-Earth-like conditions. We revisit It follows that the duration between events provides a metric this argument quantitatively in a Bayesian statistical framework. By (however imperfect) of the probability or rate of the events. constructing a simple model of the probability of abiogenesis, we calculate a Bayesian estimate of its posterior probability, given the The time-span between when Earth achieved pre-biotic condi- data that life emerged fairly early in Earth's history and that, billions tions suitable for abiogenesis plus generally habitable climatic of years later, curious creatures noted this fact and considered its conditions [5, 6, 7] and when life first arose, therefore, seems implications. -
Lecture 9—Is the Earth Rare?
41st Saas-Fee Course From Planets to Life 3-9 April 2011 Lecture 9—Is the Earth Rare? List of Rare Earth arguments/ Nitrogen abundance/ Frequency of large impacts/ Chaotic obliquity fluctuations J. F. Kasting The Gaia hypothesis First presented in the 1970s by James Lovelock 1979 1988 • Life itself is what stabilizes planetary environments • Corollary: A planet might need to be inhabited in order to remain habitable The Medea and Rare Earth hypotheses Peter Ward 2009 2000 Medea hypothesis: Life is harmful to the Earth! Rare Earth hypothesis: Complex life (animals, including humans) is rare in the universe Additional support for the Rare Earth hypothesis • Lenton and Watson think that complex life (animal life) is rare because it requires a series of unlikely evolutionary events – the origin of life – the origin of the genetic code – the development of oxygenic photosynthesis) – the origin of eukaryotes – the origin of sexuality 2011 Rare Earth/Gaia arguments 1. Plate tectonics is rare --We have dealt with this already. Plate tectonics is not necessarily rare, but it requires liquid water. Thus, a planet needs to be within the habitable zone. 2. Other planets may lack magnetic fields and may therefore have harmful radiation environments and be subject to loss of atmosphere – We have talked about this one also. Venus has retained its atmosphere. The atmosphere itself provides protection against cosmic rays 3. The animal habitable zone (AHZ) is smaller than the habitable zone (HZ) o – AHZ definition: Ts = 0-50 C o – HZ definition: Ts = 0-100 C. But this is wrong! For a 1-bar atmosphere like Earth, o water loss begins when Ts reaches 60 C. -
The 29Th Annual Meeting the 29Th Annual Meeting of the Society Took Place on April 17Th, 2016 Program and Abstracts Program
The 29th annual meeting The 29th annual meeting of the society took place on April 17th, 2016 Program and Abstracts Program: Program of the 29th annual meeting Time Lecturer Lecture Title 8:45- Refreshments & Gathering 9:05 Session 1 -Astrobiology (Doron Lancet, Chair; Amri Wandel, Organizer) 9:05- Gonen Ashkenasy Opening Remarks 9:15 (BGU) 9:15- Ravit Helled Methane-Rich Planets and the Characterization of Exoplanets 9:45 (TAU) 9:45- Sohan Jheeta (NoR Formation of Glycolaldehyde (HOCH2CHO) from Pure 10:10 HGT, LUCA) Methanol in Astrophysical Ice Analogues 10:10- Joseph Is Liquid Water Essential for Life? A Reassessment 10:35 Gale (HUJI) 10:35- Coffee break 11:00 Session 2 - Evolution (Addy Pross, Chair) 11:00- Robert Pascal Identifying the Kinetic, Thermodynamic and Chemical 11:40 (CNRS Conditions for Stability and Complexity in Living Systems Montpellier) 11:40- Omer Markovitch Predicting Proto-Species Emergence in Complex Networks 12:05 (Newcastle) 12:05- Amir Aharoni Engineering a Species Barrier in Yeast 12:30 (BGU) 12:30- Jayanta Nanda Spontaneous Evolution of β-Sheet Forming Self Replicating 12:55 (BGU) Peptides 12:55- Lunch 14:05 Session 3 - Origins of Order and Complexity (Gonen Ashkenasy, Chair; Tal Mor, Organizer) 14:05- Prof. Zvi HaCohen, Greetings 14:15 Rector (BGU) 14:15- Doron Composomics: a Common Biotic Thread 14:45 Lancet (WIS) 14:45- Avshalom Elitzur Living State Physics: Does Life's Uniqueness Elude Scientific 15:10 (IYAR) Definition? 15:10- Tal Mor Origins of Translation: Speculations about the First and the 15:35 -
Resolving the Radio Loud/Radio Quiet Dichotomy Without Thick Disks David
Resolving the radio loud/radio quiet dichotomy without thick disks David Garofalo Department of Physics, Kennesaw State University, Marietta GA 30060, USA Abstract Observations of radio loud active galaxies in the XMM-Newton archive by Mehdipour & Costantini show a strong anti-correlation between the column density of the ionized wind and the radio loudness parameter, providing evidence that jets may thrive in thin disks. This is in contrast with decades of analytic and numerical work suggesting jet formation is contingent on the presence of an inner, geometrically thick disk structure, which serves to both collimate and accelerate the jet. Thick disks emerge in radiatively inefficient disks which are associated with sub-Eddington as well as super-Eddington accretion regimes yet we show that the inverse correlation between winds and jets survives where it should not, namely in a luminosity regime normally attributed to radio quiet active galaxies which are modeled with thin disks. This along with other lines of evidence argues against thick disks as the foundation behind the radio loud/radio quiet dichotomy, opening up the possibility that jetted versus non jetted black holes may be understood within the context of radiatively efficient thin disk accretion. 1. Introduction Sikora et al (2007) explored the inverse correlation between radio loudness and Eddington accretion rate for a large sample of active galaxies (AGN) including Seyfert galaxies and LINERs, optically selected quasars, FRI radio galaxies, FRII quasars, and broad line radio galaxies. Despite a clear dichotomy in radio loudness between objects referred to as radio loud and those as radio quiet, the data was insufficiently detailed to shed light on the jet-disk connection near the Eddington limit where we traditionally model the radio quiet subset of the AGN family. -
A Theoretical Astro-Biological Solution for Femi's Paradox
2019 International Conference on Social Science, Economics and Management Research (SSEMR 2019) ISBN: 978-1-60595-638-1 A Theoretical Astro-biological Solution for Femi’s Paradox Xiang-rui LUO* and Wei WANG University of North Carolina at Chapel Hill, NC, USA Guiyang University, Guizhou, China *Corresponding author Keywords: Astrophysics, Femi’s paradox, Extraterrestrial civilizations. Abstract. The Great Filter Theory is a commonly accepted solution for Fermi’s Paradox, indicating that there is a huge wall preventing the intelligent species from achieving Level III Civilization, Galactic Civilization, which has the ability to control the energy on the scale its entire galaxy. There are many forms of hypothesis about what the Great Filter is, such as unbreakable light speed limit. Here we analyze the hypothesis that the Great Filter is the irreconcilable predicament between advanced technology and limited lifespan, which inevitably leads to stagnation in technology development. Introduction The Fermi paradox, or Fermi's paradox is the apparent contradiction between the lack of evidence and high probability estimates for the existence of extraterrestrial civilizations. The basic reasoning line, made by physicists Enrico Fermi (1901–1954) and Michael H. Hart (born 1932), are: There are at least 100 billion planets in our Galaxy alone (Cassan et al. 2012), and about 20% are of habitable zone (Petigura et al. 2013). With high probability, some of these stars have Earth-like planets, and if the Earth is typical, some may have developed intelligent life. Some of these civilizations may have developed interstellar travel, a step the Earth is investigating now. Even at the slow pace of currently envisioned interstellar travel, the Milky Way galaxy could be completely traversed in a few million years. -
Transcript-Life-Beyond-Earth-Mind-Man
Video Transcript for Archival Research Catalog (ARC) Identifier 649452 Life Beyond Earth and the Mind of Man – 1975 Ashley Montagu: When we speak of life beyond Earth, what we generally mean is of course intelligent life, something resembling our noble selves. It is highly probable that there are such intelligent forms of life in other galaxies in the universe. And it is even more probable that many of these forms are vastly more intelligent than we. Philip Morrison: It is conceivable that a spherical ship will land in front of the Washington Monument and a figure with four antennas and otherwise looking like a professional football player will walk out and demand to see our leader. But I hope very much that the universe of circumstance is wider than the rather shoddy imaginations of science fiction writers for 30 or 40 years. And I’m pretty convinced it is. We’ve not found their guidance so great in any but the most modest activities, like going to the Moon, which is not very much. George Wald: May I reply to that one. Narrator: Life Beyond Earth – George Wald: You see, this is a beautiful exposition of the myths we live with. Narrator: – and the Mind of Man, a symposium on extraterrestrial life and some of its implications for us all. Sponsored jointly by NASA and Boston University and chaired by Professor Richard Berendzen. Richard Berendzen: Let me briefly introduce the panel. On the far side is Dr. Ashley Montagu who’s a world-renowned anthropologist and social biologist. Next to him is Dr. -
Monday, November 13, 2017 WHAT DOES IT MEAN to BE HABITABLE? 8:15 A.M. MHRGC Salons ABCD 8:15 A.M. Jang-Condell H. * Welcome C
Monday, November 13, 2017 WHAT DOES IT MEAN TO BE HABITABLE? 8:15 a.m. MHRGC Salons ABCD 8:15 a.m. Jang-Condell H. * Welcome Chair: Stephen Kane 8:30 a.m. Forget F. * Turbet M. Selsis F. Leconte J. Definition and Characterization of the Habitable Zone [#4057] We review the concept of habitable zone (HZ), why it is useful, and how to characterize it. The HZ could be nicknamed the “Hunting Zone” because its primary objective is now to help astronomers plan observations. This has interesting consequences. 9:00 a.m. Rushby A. J. Johnson M. Mills B. J. W. Watson A. J. Claire M. W. Long Term Planetary Habitability and the Carbonate-Silicate Cycle [#4026] We develop a coupled carbonate-silicate and stellar evolution model to investigate the effect of planet size on the operation of the long-term carbon cycle, and determine that larger planets are generally warmer for a given incident flux. 9:20 a.m. Dong C. F. * Huang Z. G. Jin M. Lingam M. Ma Y. J. Toth G. van der Holst B. Airapetian V. Cohen O. Gombosi T. Are “Habitable” Exoplanets Really Habitable? A Perspective from Atmospheric Loss [#4021] We will discuss the impact of exoplanetary space weather on the climate and habitability, which offers fresh insights concerning the habitability of exoplanets, especially those orbiting M-dwarfs, such as Proxima b and the TRAPPIST-1 system. 9:40 a.m. Fisher T. M. * Walker S. I. Desch S. J. Hartnett H. E. Glaser S. Limitations of Primary Productivity on “Aqua Planets:” Implications for Detectability [#4109] While ocean-covered planets have been considered a strong candidate for the search for life, the lack of surface weathering may lead to phosphorus scarcity and low primary productivity, making aqua planet biospheres difficult to detect.