Relative Likelihood of Success in the Searches for Primitive Versus
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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. -
Interstellar Communication: the Case for Spread Spectrum
Interstellar Communication: The Case for Spread Spectrum David G Messerschmitta aDepartment of Electrical Engineering and Computer Sciences, 253 Cory Hall, University of California, Berkeley, California 94720-1770, USA, [email protected], 1-925-465-5740 Abstract Spread spectrum, widely employed in modern digital wireless terrestrial radio systems, chooses a signal with a noise-like character and much higher bandwidth than necessary. This paper advocates spread spectrum modulation for interstellar communication, motivated by robust immunity to radio- frequency interference (RFI) of technological origin in the vicinity of the receiver while preserving full detection sensitivity in the presence of natural sources of noise. Receiver design for noise immunity alone provides no basis for choosing a signal with any specific character, therefore failing to reduce ambiguity. By adding RFI to noise immunity as a design objective, the conjunction of choice of signal (by the transmitter) together with optimum detection for noise immunity (in the receiver) leads through simple probabilistic argument to the conclusion that the signal should possess the statistical properties of a burst of white noise, and also have a large time-bandwidth product. Thus spread spectrum also provides an implicit coordination between transmitter and receiver by reducing the ambiguity as to the signal character. This strategy requires the receiver to guess the specific noise-like signal, and it is contended that this is feasible if an appropriate pseudorandom signal is generated algorithmically. For example, conceptually simple algorithms like the binary expansion of common irrational numbers like π are shown to be suitable. Due to its deliberately wider bandwidth, spread spectrum is more susceptible to dispersion and distortion in propagation through the interstellar medium, desirably reducing ambiguity in parameters like bandwidth and carrier frequency. -
A Direct Communication Proposal to Test the Zoo Hypothesis
Space Policy 38 (2016) 22e26 Contents lists available at ScienceDirect Space Policy journal homepage: www.elsevier.com/locate/spacepol Viewpoint A direct communication proposal to test the Zoo Hypothesis Joao~ Pedro de Magalhaes~ Institute of Integrative Biology, University of Liverpool, Biosciences Building, Room 245, Crown Street, Liverpool, L69 7ZB, UK article info abstract Article history: Whether we are alone in the universe is one of the greatest mysteries facing humankind. Given the >100 Received 3 March 2016 billion stars in our galaxy, many have argued that it is statistically unlikely that life, including intelligent Accepted 16 June 2016 life, has not emerged anywhere else. The lack of any sign of extraterrestrial intelligence, even though on a Available online 26 July 2016 cosmic timescale extraterrestrial civilizations would have enough time to cross the galaxy, is known as Fermi's Paradox. One possible explanation for Fermi's Paradox is the Zoo Hypothesis which states that Keywords: one or more extraterrestrial civilizations know of our existence and can reach us, but have chosen not to Active SETI disturb us or even make their existence known to us. I propose here a proactive test of the Zoo Hy- Astrobiology fi Fermi's Paradox pothesis. Speci cally, I propose to send a message using television and radio channels to any extrater- Messaging to extraterrestrial intelligence restrial civilization(s) that might be listening and inviting them to respond. Even though I accept this is METI unlikely to be successful in the sense of resulting in a response from extraterrestrial intelligences, the possibility that extraterrestrial civilizations are monitoring us cannot be dismissed and my proposal is consistent with current scientific knowledge. -
The Search for Extraterrestrial Intelligence
THE SEARCH FOR EXTRATERRESTRIAL INTELLIGENCE Are we alone in the universe? Is the search for extraterrestrial intelligence a waste of resources or a genuine contribution to scientific research? And how should we communicate with other life-forms if we make contact? The search for extraterrestrial intelligence (SETI) has been given fresh impetus in recent years following developments in space science which go beyond speculation. The evidence that many stars are accompanied by planets; the detection of organic material in the circumstellar disks of which planets are created; and claims regarding microfossils on Martian meteorites have all led to many new empirical searches. Against the background of these dramatic new developments in science, The Search for Extraterrestrial Intelligence: a philosophical inquiry critically evaluates claims concerning the status of SETI as a genuine scientific research programme and examines the attempts to establish contact with other intelligent life-forms of the past thirty years. David Lamb also assesses competing theories on the origin of life on Earth, discoveries of ex-solar planets and proposals for space colonies as well as the technical and ethical issues bound up with them. Most importantly, he considers the benefits and drawbacks of communication with new life-forms: how we should communicate and whether we could. The Search for Extraterrestrial Intelligence is an important contribution to a field which until now has not been critically examined by philosophers. David Lamb argues that current searches should continue and that space exploration and SETI are essential aspects of the transformative nature of science. David Lamb is honorary Reader in Philosophy and Bioethics at the University of Birmingham. -
Searching for Extraterrestrial Intelligence
THE FRONTIERS COLLEctION THE FRONTIERS COLLEctION Series Editors: A.C. Elitzur L. Mersini-Houghton M. Schlosshauer M.P. Silverman J. Tuszynski R. Vaas H.D. Zeh The books in this collection are devoted to challenging and open problems at the forefront of modern science, including related philosophical debates. In contrast to typical research monographs, however, they strive to present their topics in a manner accessible also to scientifically literate non-specialists wishing to gain insight into the deeper implications and fascinating questions involved. Taken as a whole, the series reflects the need for a fundamental and interdisciplinary approach to modern science. Furthermore, it is intended to encourage active scientists in all areas to ponder over important and perhaps controversial issues beyond their own speciality. Extending from quantum physics and relativity to entropy, consciousness and complex systems – the Frontiers Collection will inspire readers to push back the frontiers of their own knowledge. Other Recent Titles Weak Links Stabilizers of Complex Systems from Proteins to Social Networks By P. Csermely The Biological Evolution of Religious Mind and Behaviour Edited by E. Voland and W. Schiefenhövel Particle Metaphysics A Critical Account of Subatomic Reality By B. Falkenburg The Physical Basis of the Direction of Time By H.D. Zeh Mindful Universe Quantum Mechanics and the Participating Observer By H. Stapp Decoherence and the Quantum-To-Classical Transition By M. Schlosshauer The Nonlinear Universe Chaos, Emergence, Life By A. Scott Symmetry Rules How Science and Nature are Founded on Symmetry By J. Rosen Quantum Superposition Counterintuitive Consequences of Coherence, Entanglement, and Interference By M.P. -
Interstellar Communication. Iii. Optimal Frequency to Maximize Data Rate
Draft version November 17, 2017 INTERSTELLAR COMMUNICATION. III. OPTIMAL FREQUENCY TO MAXIMIZE DATA RATE Michael Hippke1 and Duncan H. Forgan2, 3 1Sonneberg Observatory, Sternwartestr. 32, 96515 Sonneberg, Germany 2SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Scotland, KY16 9SS, UK 3St Andrews Centre for Exoplanet Science, University of St Andrews, UK ABSTRACT The optimal frequency for interstellar communication, using \Earth 2017" technology, was derived in papers I and II of this series (Hippke 2017a,b). The framework included models for the loss of photons from diffraction (free space), interstellar extinction, and atmospheric transmission. A major limit of current technology is the focusing of wavelengths λ < 300 nm (UV). When this technological constraint is dropped, a physical bound is found at λ ≈ 1 nm (E ≈ keV) for distances out to kpc. While shorter wavelengths may produce tighter beams and thus higher data rates, the physical limit comes from surface roughness of focusing devices at the atomic level. This limit can be surpassed by beam-forming with electromagnetic fields, e.g. using a free electron laser, but such methods are not energetically competitive. Current lasers are not yet cost efficient at nm wavelengths, with a gap of two orders of magnitude, but future technological progress may converge on the physical optimum. We recommend expanding SETI efforts towards targeted (at us) monochromatic (or narrow band) X-ray emission at 0.5-2 keV energies. 1. INTRODUCTION believed to originate from intelligent beings on Mars. The idea to communicate with Extraterrestrial Intel- In the optical, William Pickering(1909) suggested to ligence was born in the 19th century. -
Dynamics of the Arecibo Radio Telescope
DYNAMICS OF THE ARECIBO RADIO TELESCOPE Ramy Rashad 110030106 Department of Mechanical Engineering McGill University Montreal, Quebec, Canada February 2005 Under the supervision of Professor Meyer Nahon Abstract The following thesis presents a computer and mathematical model of the dynamics of the tethered subsystem of the Arecibo Radio Telescope. The computer and mathematical model for this part of the Arecibo Radio Telescope involves the study of the dynamic equations governing the motion of the system. It is developed in its various components; the cables, towers, and platform are each modeled in succession. The cable, wind, and numerical integration models stem from an earlier version of a dynamics model created for a different radio telescope; the Large Adaptive Reflector (LAR) system. The study begins by converting the cable model of the LAR system to the configuration required for the Arecibo Radio Telescope. The cable model uses a lumped mass approach in which the cables are discretized into a number of cable elements. The tower motion is modeled by evaluating the combined effective stiffness of the towers and their supporting backstay cables. A drag model of the triangular truss platform is then introduced and the rotational equations of motion of the platform as a rigid body are considered. The translational and rotational governing equations of motion, once developed, present a set of coupled non-linear differential equations of motion which are integrated numerically using a fourth-order Runge-Kutta integration scheme. In this manner, the motion of the system is observed over time. A set of performance metrics of the Arecibo Radio Telescope is defined and these metrics are evaluated under a variety of wind speeds, directions, and turbulent conditions. -
SETI@Home Completes a Decade of ET Search 1 May 2009
SETI@home completes a decade of ET search 1 May 2009 Over the years, improvements to the Arecibo telescope have significantly improved the quality of data available to SETI@home, and the continuous increase in the speed of the average PC has made it possible to use more sensitive and sophisticated analysis techniques. Today, SETI@home continues its search for evidence of extraterrestrial life, with greater sensitivity than ever, and its hundreds of thousands of volunteers continue to engage in lively on-line forums and in a spirited competition The SETI@home project, which has involved the for most data processed. worldwide public in a search for radio-wave evidence of life outside Earth, marks its 10th More information: anniversary on May 17, 2009. setiathome.berkeley.edu/index.php The project, based at the Space Sciences Provided by SETI@home Laboratory at the University of California, Berkeley, records and analyzes data from the world's largest radio telescope, the Arecibo Observatory in Puerto Rico. The collected computing power of hundreds of thousands of volunteer PCs is used to search this data for narrow-band signals (similar to TV or cell-phone transmissions) and other types of signals of possible extraterrestrial origin. SETI@home was conceived in 1995. Development began in 1998, with initial funding from The Planetary Society and Paramount Pictures. It was publicly launched on May 17, 1999, and the number of volunteers quickly grew to about one million. Because of the presence of noise and man-made radio interference, SETI@home doesn't get excited by individual signals. -
Why SETI Will Fail ‡
Why SETI Will Fail z B. Zuckerman1 1Department of Physics and Astronomy, University of California, Los Angeles, CA 90095, USA E-mail: [email protected] Abstract. The union of space telescopes and interstellar spaceships guarantees that if extraterrestrial civilizations were common, someone would have come here long ago. PACS numbers: 97.10.Tk arXiv:1912.08386v1 [physics.pop-ph] 18 Dec 2019 z This article originally appeared in the September/October 2002 issue of Mercury magazine (published by the Astronomical Society of the Pacific). Why SETI Will Fail 2 1. Introduction Where do humans stand on the scale of cosmic intelligence? For most people, this question ranks at or very near the top of the list of "scientific things I would like to know." Lacking hard evidence to constrain the imagination, optimists conclude that technological civilizations far in advance of our own are common in our Milky Way Galaxy, whereas pessimists argue that we Earthlings probably have the most advanced technology around. Consequently, this topic has been debated endlessly and in numerous venues. Unfortunately, significant new information or ideas that can point us in the right direction come along infrequently. But recently I have realized that important connections exist between space astronomy and space travel that have never been discussed in the scientific or popular literature. These connections clearly favor the more pessimistic scenario mentioned above. Serious radio searches for extraterrestrial intelligence (SETI) have been conducted during the past few decades. Brilliant scientists have been associated with SETI, starting with pioneers like Frank Drake and the late Carl Sagan and then continuing with Paul Horowitz, Jill Tarter, and the late Barney Oliver. -
Nasa and the Search for Technosignatures
NASA AND THE SEARCH FOR TECHNOSIGNATURES A Report from the NASA Technosignatures Workshop NOVEMBER 28, 2018 NASA TECHNOSIGNATURES WORKSHOP REPORT CONTENTS 1 INTRODUCTION .................................................................................................................................................................... 1 What are Technosignatures? .................................................................................................................................... 2 What Are Good Technosignatures to Look For? ....................................................................................................... 2 Maturity of the Field ................................................................................................................................................... 5 Breadth of the Field ................................................................................................................................................... 5 Limitations of This Document .................................................................................................................................... 6 Authors of This Document ......................................................................................................................................... 6 2 EXISTING UPPER LIMITS ON TECHNOSIGNATURES ....................................................................................................... 9 Limits and the Limitations of Limits ........................................................................................................................... -
The Search for Extra-Terrestial Intelligence in the New Millennium Transcript
The Search for Extra-Terrestial Intelligence in the New Millennium Transcript Date: Thursday, 3 April 2008 - 12:00AM THE SEARCH FOR EXTRA-TERRESTRIAL INTELLIGENCE IN THE NEW MILLENNIUM Professor Ian Morison SETI, the Search for Extra-terrestrial Intelligence, has now been actively pursued for close on 50 years without success. However this does not imply that we are alone in the Milky Way galaxy for, although most astronomers now agree that intelligent civilisations are far less common than once thought, we cannot say that there are none. But it does mean that they are likely to be at greater distances from us and, as yet, we have only seriously searched a tiny region of our galaxy. It will not be until the 2020's that an instrument, now on the drawing board, will give us the capability to detect radio signals of realistic power from across the whole galaxy. It is also possible that light, rather than radio, might be the communication carrier chosen by an alien race, but optical-SETI searches seeking out pulsed laser signals have only just begun. The story so far The subject may well have been inspired by the building of the 76m Mk1 radio telescope at Jodrell Bank in 1957. In 1959 two American astronomers, Guccione and Morrison, submitted a paper to the journal Nature in which they pointed out that, given two radio telescopes of comparable size to the Mk 1, it would be possible to communicate across interstellar distances by radio. They suggested a number of possible nearby, sun-like, stars that could be observed to see if any signals might be detected. -
The Breakthrough Listen Search for Intelligent Life: 1.1–1.9 Ghz Observations of 692 Nearby Stars
The Astrophysical Journal, 849:104 (13pp), 2017 November 10 https://doi.org/10.3847/1538-4357/aa8d1b © 2017. The American Astronomical Society. All rights reserved. The Breakthrough Listen Search for Intelligent Life: 1.1–1.9 GHz Observations of 692 Nearby Stars J. Emilio Enriquez1,2 , Andrew Siemion1,2,3 , Griffin Foster1,4 , Vishal Gajjar5 , Greg Hellbourg1, Jack Hickish6 , Howard Isaacson1 , Danny C. Price1,7 , Steve Croft1 , David DeBoer6, Matt Lebofsky1, David H. E. MacMahon6, and Dan Werthimer1,5,6 1 Department of Astronomy, University of California, Berkeley, 501 Campbell Hall #3411, Berkeley, CA, 94720, USA; [email protected] 2 Department of Astrophysics/IMAPP, Radboud University, P.O. Box 9010, NL-6500 GL Nijmegen, The Netherlands 3 SETI Institute, Mountain View, CA 94043, USA 4 University of Oxford, Sub-Department of Astrophysics, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH, UK 5 Space Science Laboratory, 7-Gauss way, University of California, Berkeley, CA, 94720, USA 6 Radio Astronomy Laboratory, University of California at Berkeley, Berkeley, CA 94720, USA 7 Centre for Astrophysics & Supercomputing, Swinburne University of Technology, PO Box 218, Hawthorn, VIC 3122, Australia Received 2017 April 20; revised 2017 September 5; accepted 2017 September 8; published 2017 November 6 Abstract We report on a search for engineered signals from a sample of 692 nearby stars using the Robert C. Byrd Green Bank Telescope, undertaken as part of the Breakthrough Listen Initiative search for extraterrestrial intelligence. Observations were made over 1.1–1.9 GHz (L band), with three sets of five-minute observations of the 692 primary targets, interspersed with five-minute observations of secondary targets.