Extraterrestrial
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44 went back to the evidence: Sergey Mashchenko, “Modeling the Light Curve of ‘Oumuamua: Evidence for Torque and Disk-Like Shape,” Monthly Notices of the Royal Astronomical Society (2019), https://arxiv.org/pdf/1906.03696.pdf.
45 melting and tidal stretching along the trajectory: Yun Zhang and Douglas N. C. Lin, “Tidal Fragmentation as the Origin of 1I/2017 U1 (‘Oumuamua),” Nature Astronomy (2020), https://arxiv.org/pdf/2004.07218.pdf.
5. THE LIGHTSAIL HYPOTHESIS
69 “we find no compelling evidence”: ‘Oumuamua ISSI Team, “The Natural History of ‘Oumuamua,” Nature Astronomy 3 (2019), https://arxiv.org/pdf/1907.01910.pdf.
69 “We have never seen anything like ‘Oumuamua”: Michelle Starr, “Astronomers Have Analysed Claims ‘Oumuamua’s an Alien Ship, and It’s Not Looking Good,” Science Alert, July 1, 2019, https://www.sciencealert.com/astronomers-have-determined-oumuamua-is-really-truly-not-an-alien-lightsail.
6. SEASHELLS AND BUOYS
76 they reached some general conclusions: Aaron Do, Michael A. Tucker, and John Tonry, “Interstellar Interlopers: Number Density and Origin of ‘Oumuamua-Like Objects,” Astrophysical Journal (2018), https://arxiv.org/pdf/1801.02821.pdf.
77 In two follow-up papers: Amaya Moro-Martin, “Origin of 1I/‘Oumuamua. I. An Ejected Protoplanetary Disk Object?,” Astrophysical Journal (2018), https://arxiv.org/pdf/1810.02148.pdf; Amaya Moro-Martin, “II. An Ejected Exo-Oort Cloud Object,” Astronomical Journal (2018), https://arxiv.org/pdf/1811.00023.pdf.
81 only one in every five hundred stars: Eric Mamajek, “Kinematics of the Interstellar Vagabond 1I/'Oumuamua (A/2017 U1),” Research Notes of the American Astronomical Society (2017), https://arxiv.org/abs/1710.11364.
7. LEARNING FROM CHILDREN
90 two simple conjectures: Giuseppe Cocconi and Philip Morrison, “Searching for Interstellar Communications,” Nature 184, no. 4690 (September 19, 1959): 844–46, http://www.iaragroup.org/_OLD/seti/pdf_IARA/cocconi.pdf.
93 “Millions have been spent”: Adam Mann, “Intelligent Ways to Search for Extraterrestrials,” New Yorker (October 3, 2019).
107 currently on track: Jason Wright, “SETI Is a Very Young Field (Academically),” AstroWright (blog), January 23, 2019, https://sites.psu.edu/astrowright/2019/01/23/seti-is-a-very-young-field-academically/.
9. FILTERS
122 the World Bank issued a report: Silpa Kaza et al., “What a Waste 2.0: A Global Snapshot of Solid Waste Management to 2050,” World Bank (2018), https://openknowledge.worldbank.org/handle/10986/30317.
128 “I am not sufficiently conceited”: Mario Livio, “Winston Churchill’s Essay on Alien Life Found,” Nature (2017), https://www.nature.com/news/winston-churchill-s-essay-on-alien-life-found-1.21467; Brian Handwerk, “‘Are We Alone in the Universe?’ Winston Churchill’s Lost Extraterrestrial Essay Says No,” SmithsonianMag.com, February 16, 2017, https://www.smithsonianmag.com/science-nature/winston-churchill-question-alien-life-180962198/.
13. SINGULARITIES
184 “Last week in New York”: You can watch a video of Hawking’s brief speech at my family’s home on April 22, 2016, at this link: https://www.cfa.harvard.edu/~loeb/SI.html.
CONCLUSION
195 “It seemed we had answered”: Gilbert V. Levin, “I’m Convinced We Found Evidence of Life on Mars in the 1970s,” Scientific American, October 10, 2019, https://blogs.scientificamerican.com/observations/im-convinced-we-found-evidence-of-life-on-mars-in-the-1970s/.
AFTERWORD
197 in the UK had discovered: Greaves, J. et al., “Phosphine Gas in the Cloud Decks of Venus,” Nature Astronomy (2020), https://arxiv.org/ftp/arxiv/papers/2009/2009.06593.pdf.
197 microbes could live inside liquid droplets: Seager, S. et al., “The Venusian Lower Atmosphere Haze as a Depot for Desiccated Microbial Life: A Proposed Life Cycle for Persistence of the Venusian Aerial Biosphere,” Astrobiology (2020), https://arxiv.org/ftp/arxiv/papers/2009/2009.06474.pdf.
198 with Manasvi Lingam I calculated: Lingam, M., and A. Loeb, “On the Biomass Required to Produce Phosphine Detected in the Cloud Decks of Venus,” arXiv.org (2020), https://arxiv.org/pdf/2009.07835.pdf.
198 Amir Siraj and I showed: Siraj, A., and A. Loeb, “Transfer of Life Between Earth and Venus with Planet-Grazing Asteroids,” arXiv.org (2020), https://arxiv.org/pdf/2009.09512.pdf.
Additional Reading
Many of the ideas covered in this book were first broached and explored in my previously published articles. A list, with hyperlinks, is available here: https://www.cfa.harvard.edu/~loeb/Oumuamua.html.
Below are some of my articles for additional enrichment on the topics of each chapter. All URLs provided for academic journal articles in this section and the next direct to the arXiv, a preprint server that makes academic papers available to the scientific community and the general public.
Introduction
Loeb, A. “The Case for Cosmic Modesty.” Scientific American, June 28, 2017, https://blogs.scientificamerican.com/observations/the-case-for-cosmic-modesty/.
———. “Science Is Not About Getting More Likes.” Scientific American, October 8, 2019, https://blogs.scientificamerican.com/observations/science-is-not-about-getting-more-likes/.
———. “Seeking the Truth When the Consensus Is Against You.” Scientific American, November 9, 2018, https://blogs.scientificamerican.com/observations/seeking-the-truth-when-the-consensus-is-against-you/.
———. “Essential Advice for Fledgling Scientists.” Scientific American, December 2, 2019, https://blogs.scientificamerican.com/observations/essential-advice-for-fledgling-scientists/.
———. “A Tale of Three Nobels.” Scientific American, December 18, 2019, https://blogs.scientificamerican.com/observations/a-tale-of-three-nobels/.
———. “Advice to Young Scientists: Be a Generalist.” Scientific American, March 16, 2020, https://blogs.scientificamerican.com/observations/advice-for-young-scientists-be-a-generalist/.
———. “The Power of Scientific Brainstorming.” Scientific American, July 23, 2020, https://www.scientificamerican.com/article/the-power-of-scientific-brainstorming/.
———. “A Movie of the Evolving Universe Is Potentially Scary.” Scientific American, August 2, 2020. https://www.scientificamerican.com/article/a-movie-of-the-evolving-universe-is-potentially-scary/.
Moro-Martin, A., E. L. Turner, and A. Loeb. “Will the Large Synoptic Survey Telescope Detect Extra-Solar Planetesimals Entering the Solar System?” Astrophysical Journal (2009), https://arxiv.org/pdf/0908.3948.pdf.
1. Scout
Bialy, S., and A. Loeb. “Could Solar Radiation Pressure Explain ‘Oumuamua’s Peculiar Acceleration?” Astrophysical Journal Letters (2018), https://arxiv.org/pdf/1810.11490.pdf.
Loeb, A. “Searching for Relics of Dead Civilizations.” Scientific American, September 27, 2018, https://blogs.scientificamerican.com/observations/how-to-search-for-dead-cosmic-civilizations/.
———. “Are Alien Civilizations Technologically Advanced?” Scientific American, January 8, 2018, https://blogs.scientificamerican.com/observations/are-alien-civilizations-technologically-advanced/.
———. “Q&A with a Journalist.” Center for Astrophysics, Harvard University, January 25, 2019, https://www.cfa.harvard.edu/~loeb/QA.pdf.
2. The Farm
Loeb, A. “The Humanities and the Future.” Scientific American, March 22, 2019, https://blogs.scientificamerican.com/observations/the-humanities-and-the-future/.
———. “What Is the One Thing You Would Change About the World?” Harvard Gazette, July 1, 2019, https://news.harvard.edu/gazette/story/2019/06/focal-point-harvard-professor-avi-loeb-wants-more-scientists-to-think-like-children/.
———. “Science as a Way of Life.” Scientific American, August 14, 2019, https://blogs.scientificamerican.com/observations/a-scientist-must-go-where-the-evidence-leads/.
———. “Beware of Theories of Everything.” Scientific American, June 9, 2020, https://blogs.scientificamerican
.com/observations/beware-of-theories-of-everything/.
Loeb, A., and E. L. Turner. “Detection Technique for Artificially Illuminated Objects in the Outer Solar System and Beyond.” Astrobiology (2012), https://arxiv.org/pdf/1110.6181.pdf.
3. Anomalies
Hoang, T., and A. Loeb. “Destruction of Molecular Hydrogen Ice and Implications for 1I/2017 U1 (‘Oumuamua).” Astrophysical Journal Letters (2020), https://arxiv.org/pdf/2006.08088.pdf.
Lingam, M., and A. Loeb. “Implications of Captured Interstellar Objects for Panspermia and Extraterrestrial Life.” Astrophysical Journal (2018), https://arxiv.org/pdf/1801.10254.pdf.
Loeb, A. “Theoretical Physics Is Pointless Without Experimental Tests.” Scientific American, August 10, 2018, https://blogs.scientificamerican.com/observations/theoretical-physics-is-pointless-without-experimental-tests/.
———. “The Power of Anomalies.” Scientific American, August 28, 2018, https://blogs.scientificamerican.com/observations/the-power-of-anomalies/.
———. “On ‘Oumuamua.” Center for Astrophysics, Harvard University, November 5, 2018, https://www.cfa.harvard.edu/~loeb/Oumuamua.pdf.
———. “Six Strange Facts About the First Interstellar Visitor, ‘Oumuamua.” Scientific American, November 20, 2018, https://blogs.scientificamerican.com/observations/6-strange-facts-about-the-interstellar-visitor-oumuamua/.
———. “How to Approach the Problem of ‘Oumuamua.” Scientific American, December 19, 2018, https://blogs.scientificamerican.com/observations/how-to-approach-the-problem-of-oumuamua/.
———. “The Moon as a Fishing Net for Extraterrestrial Life.” Scientific American, September 25, 2019, https://blogs.scientificamerican.com/observations/the-moon-as-a-fishing-net-for-extraterrestrial-life/.
———. “The Simple Truth About Physics.” Scientific American, January 1, 2020, https://blogs.scientificamerican.com/observations/the-simple-truth-about-physics/.
Sheerin, T. F., and A. Loeb. “Could 1I/2017 U1 ‘Oumuamua Be a Solar Sail Hybrid?” Center for Astrophysics, Harvard University, May 2020, https://www.cfa.harvard.edu/~loeb/TL.pdf.
Siraj, A., and A. Loeb. “ ‘Oumuamua’s Geometry Could Be More Extreme than Previously Inferred.” Research Notes of the American Astronomical Society (2019), http://iopscience.iop.org/article/10.3847/2515-5172/aafe7c/meta.
———. “Identifying Interstellar Objects Trapped in the Solar System Through Their Orbital Parameters.” Astrophysical Journal Letters (2019), https://arxiv.org/pdf/1811.09632.pdf.
———. “An Argument for a Kilometer-Scale Nucleus of C/2019 Q4.” Research Notes of the American Astronomical Society (2019), https://arxiv.org/pdf/1909.07286.pdf.
4. StarChips
Christian, P., and A. Loeb. “Interferometric Measurement of Acceleration at Relativistic Speeds.” Astrophysical Journal (2017), https://arxiv.org/pdf/1608.08230.pdf.
Guillochon, J., and A. Loeb. “SETI via Leakage from Light Sails in Exoplanetary Systems.” Astrophysical Journal (2016), https://arxiv.org/pdf/1508.03043.pdf.
Kreidberg, L., and A. Loeb. “Prospects for Characterizing the Atmosphere of Proxima Centauri b.” Astrophysical Journal Letters (2016), https://arxiv.org/pdf/1608.07345.pdf.
Loeb, A. “On the Habitability of the Universe.” Consolidation of Fine Tuning (2016), https://arxiv.org/pdf/1606.08926.pdf.
———. “Searching for Life Among the Stars.” Pan European Networks: Science and Technology, July 2017, https://www.cfa.harvard.edu/~loeb/PEN.pdf.
———. “Breakthrough Starshot: Reaching for the Stars.” SciTech Europa Quarterly, March 2018, https://www.cfa.harvard.edu/~loeb/Loeb_Starshot.pdf.
———. “Sailing on Light.” Forbes, August 8, 2018, https://www.cfa.harvard.edu/~loeb/Loeb_Forbes.pdf.
———. “Interstellar Escape from Proxima b Is Barely Possible with Chemical Rockets.” Scientific American, 2018, https://arxiv.org/pdf/1804.03698.pdf.
Loeb, A., R. A. Batista, and D. Sloan. “Relative Likelihood for Life as a Function of Cosmic Time.” Journal of Cosmology and Astroparticle Physics (2016), https://arxiv.org/pdf/1606.08448.pdf.
Manchester, Z., and A. Loeb. “Stability of a Light Sail Riding on a Laser Beam.” Astrophysical Journal Letters (2017), https://arxiv.org/pdf/1609.09506.pdf.
5. The Lightsail Hypothesis
Hoang, T., and A. Loeb. “Electromagnetic Forces on a Relativistic Spacecraft in the Interstellar Medium.” Astrophysical Journal (2017), https://arxiv.org/pdf/1706.07798.pdf.
Hoang, T., A. Lazarian, B. Burkhart, and A. Loeb. “The Interaction of Relativistic Spacecrafts with the Interstellar Medium.” Astrophysical Journal (2017), https://arxiv.org/pdf/1608.05284.pdf.
Hoang, T., A. Loeb, A. Lazarian, and J. Cho. “Spinup and Disruption of Interstellar Asteroids by Mechanical Torques, and Implications for 1I/2017 U1 (‘Oumuamua).” Astrophysical Journal (2018), https://arxiv.org/pdf/1802.01335.pdf.
Loeb, A. “An Audacious Explanation for Fast Radio Bursts.” Scientific American, June 24, 2020, https://www.scientificamerican.com/article/an-audacious-explanation-for-fast-radio-bursts/.
6. Seashells and Buoys
Lingam, M., and A. Loeb. “Risks for Life on Habitable Planets from Superflares of Their Host Stars.” Astrophysical Journal (2017), https://arxiv.org/pdf/1708.04241.pdf.
———. “Optimal Target Stars in the Search for Life.” Astrophysical Journal Letters (2018), https://arxiv.org/pdf/1803.07570.pdf.
Loeb, A. “For E.T. Civilizations, Location Could Be Everything.” Scientific American, March 13, 2018, https://blogs.scientificamerican.com/observations/for-e-t-civilizations-location-could-be-everything/.
———. “Space Archaeology.” Atmos, November 8, 2019, https://www.cfa.harvard.edu/~loeb/Atmos_Loeb.pdf.
Siraj, A., and A. Loeb. “Radio Flares from Collisions of Neutron Stars with Interstellar Asteroids.” Research Notes of the American Astronomical Society (2019), https://arxiv.org/pdf/1908.11440.pdf.
———. “Observational Signatures of Sub-Relativistic Meteors.” Astrophysical Journal Letters (2020), https://arxiv.org/pdf/2002.01476.pdf.
7. Learning from Children
Lingam, M., and A. Loeb. “Fast Radio Bursts from Extragalactic Light Sails.” Astrophysical Journal Letters (2017), https://arxiv.org/pdf/1701.01109.pdf.
———. “Relative Likelihood of Success in the Searches for Primitive Versus Intelligent Life.” AstroBiology (2019), https://arxiv.org/pdf/1807.08879.pdf.
8. Vastness
Loeb, A. “Geometry of the Universe.” Astronomy, July 8, 2020, https://www.cfa.harvard.edu/~loeb/Geo.pdf.
———. How Did the First Stars and Galaxies Form? Princeton, NJ: Princeton University Press, 2010.
Loeb, A., and S. R. Furlanetto. The First Galaxies in the Universe. Princeton, NJ: Princeton University Press, 2013.
Loeb, A., and M. Zaldarriaga. “Eavesdropping on Radio Broadcasts from Galactic Civilizations with Upcoming Observatories for Redshifted 21 Cm Radiation.” Journal of Cosmology and Astroparticle Physics (2007), https://arxiv.org/pdf/astro-ph/0610377.pdf.
9. Filters
Lingam, M., and A. Loeb. “Propulsion of Spacecrafts to Relativistic Speeds Using Natural Astrophysical Sources.” Astrophysical Journal (2020), https://arxiv.org/pdf/2002.03247.pdf.
Loeb, A. “Our Future in Space Will Echo Our Future on Earth.” Scientific American, January 10, 2019, https://blogs.scientificamerican.com/observations/our-future-in-space-will-echo-our-future-on-earth/.
———. “When Lab Experiments Carry Theological Implications.” Scientific American, April 22, 2019, https://blogs.scientificamerican.com/observations/when-lab-experiments-carry-theological-implications/.
———. “The Only Thing That Remains Constant Is Change.” Scientific American, September 6, 2019, https://blogs.scientificamerican.com/observations/the-only-thing-that-remains-constant-is-change/.
Siraj, A., and A. Loeb. “Exporting Terrestrial Life Out of the Solar System with Gravi
tational Slingshots of Earthgrazing Bodies.” International Journal of Astrobiology (2019), https://arxiv.org/pdf/1910.06414.pdf.
10. Astro-Archaeology
Lin, H. W., G. Gonzalez Abad, and A. Loeb. “Detecting Industrial Pollution in the Atmospheres of Earth-Like Exoplanets.” Astrophysical Journal Letters (2014), https://arxiv.org/pdf/1406.3025.pdf.
Lingam, M., and A. Loeb. “Natural and Artificial Spectral Edges in Exoplanets.” Monthly Notices of the Royal Astronomical Society (2017), https://arxiv.org/pdf/1702.05500.pdf.
Loeb, A. “Making the Church Taller.” Scientific American, October 18, 2018, https://blogs.scientificamerican.com/observations/making-the-church-taller/.
———. “Advanced Extraterrestrials as an Approximation to God.” Scientific American, January 26, 2019, https://blogs.scientificamerican.com/observations/advanced-extraterrestrials-as-an-approximation-to-god/.
———. “Are We Really the Smartest Kid on the Cosmic Block?” Scientific American, March 4, 2019, https://blogs.scientificamerican.com/observations/are-we-really-the-smartest-kid-on-the-cosmic-block/.
———. “Visionary Science Takes More Than Just Technical Skills.” Scientific American, May 25, 2020, https://blogs.scientificamerican.com/observations/visionary-science-takes-more-than-just-technical-skills/.
11. ‘Oumuamua’s Wager
Chen, H., J. C. Forbes, and A. Loeb. “Habitable Evaporated Cores and the Occurrence of Panspermia near the Galactic Center.” Astrophysical Journal Letters (2018), https://arxiv.org/pdf/1711.06692.pdf.