tag:theconversation.com,2011:/us/topics/fermi-paradox-35915/articles
Fermi Paradox – The Conversation
2022-10-21T12:38:07Z
tag:theconversation.com,2011:article/191054
2022-10-21T12:38:07Z
2022-10-21T12:38:07Z
Signatures of alien technology could be how humanity first finds extraterrestrial life
<figure><img src="https://images.theconversation.com/files/490943/original/file-20221020-21-mv2tjy.jpg?ixlib=rb-1.1.0&rect=80%2C477%2C3753%2C1678&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Astronomers have been looking for radio waves sent by a distant civilization for more than 60 years.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/illustration-of-signal-coming-out-the-deep-cosmos-royalty-free-image/1338115983?phrase=signal%20coming%20from%20planet%20space&adppopup=true">Rytis Bernotas/iStock via Getty Images</a></span></figcaption></figure><p>If an alien were to look at Earth, many human technologies – from cell towers to fluorescent light bulbs – could be a beacon signifying the presence of life. </p>
<p><a href="https://sites.psu.edu/macyhuston/">We are</a> two <a href="https://sites.psu.edu/astrowright">astronomers</a> <a href="https://scholar.google.com/citations?user=lEUxaaIAAAAJ&hl=en&oi=ao">who</a> work on the <a href="https://www.pseti.psu.edu/about/">search for extraterrestrial intelligence</a> – or SETI. In our research, we try to characterize and detect signs of technology originating from beyond Earth. These are called technosignatures. While scanning the sky for a TV broadcast of some extraterrestrial Olympics may sound straightforward, searching for signs of distant, advanced civilizations is a much more nuanced and difficult task than it might seem.</p>
<h2>Saying ‘hello’ with radios and lasers</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/490923/original/file-20221020-1663-tvwgzj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A laser shooting up from an observatory into a starry sky." src="https://images.theconversation.com/files/490923/original/file-20221020-1663-tvwgzj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/490923/original/file-20221020-1663-tvwgzj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=902&fit=crop&dpr=1 600w, https://images.theconversation.com/files/490923/original/file-20221020-1663-tvwgzj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=902&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/490923/original/file-20221020-1663-tvwgzj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=902&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/490923/original/file-20221020-1663-tvwgzj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1133&fit=crop&dpr=1 754w, https://images.theconversation.com/files/490923/original/file-20221020-1663-tvwgzj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1133&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/490923/original/file-20221020-1663-tvwgzj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1133&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A laser – like the one seen here – or beam of radio waves pointed intentionally at Earth would be a strong sign of extraterrestrial life.</span>
<span class="attribution"><a class="source" href="http://www.eso.org/public/images/gerd_huedepohl_4/">G. Hüdepohl/ESO</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
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<p>The modern scientific <a href="https://astrobites.org/2021/08/16/classic-paper-summary/">search for extraterrestrial intelligence began in 1959</a> when astronomers Giuseppe Cocconi and Philip Morrison showed that radio transmissions from Earth <a href="https://doi.org/10.4159/harvard.9780674366688.c9">could be detected</a> by radio telescopes at interstellar distances. The same year, <a href="https://theconversation.com/frank-drake-has-passed-away-but-his-equation-for-alien-intelligence-is-more-important-than-ever-189935">Frank Drake</a>, launched the first SETI search, <a href="https://www.seti.org/project-ozma">Project Ozma</a>, by pointing a large radio telescope at two nearby Sun-like stars to see if he could detect any radio signals coming from them. Following the invention of the laser in 1960, astronomers showed that visible light could also <a href="https://doi.org/10.1038/190205a0">be detected from distant planets</a>.</p>
<p>These first, foundational attempts to detect <a href="http://www.bigear.org/oldseti.htm">radio</a> or <a href="https://doi.org/110.1086/423300">laser</a> signals from another civilization were all looking for focused, powerful signals that would have been intentionally sent to the solar system and meant to be found. </p>
<p>Given the technological limitations of the 1960s, astronomers did not give serious thought to searching for broadcast signals – like television and radio broadcasts on Earth – that would leak into space. But a beam of a radio signal, with all of its power focused towards Earth, could be detectable from much farther away – just picture the difference between a laser and a weak light bulb.</p>
<p>The search for intentional radio and laser signals is still one of the most popular SETI strategies today. However, this approach <a href="https://www.universetoday.com/149513/beyond-fermis-paradox-xvii-what-is-the-seti-paradox-hypothesis/">assumes that extraterrestrial civilizations want to communicate</a> with other technologically advanced life. Humans very rarely send targeted signals into space, and some scholars argue that intelligent species may <a href="https://theconversation.com/blasting-out-earths-location-with-the-hope-of-reaching-aliens-is-a-controversial-idea-two-teams-of-scientists-are-doing-it-anyway-182036">purposefully avoid broadcasting out their locations</a>. This search for signals that no one may be sending is called <a href="https://doi.org/10.48550/arXiv.physics/0611283">the SETI Paradox</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/490932/original/file-20221020-1690-8mwnqz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An aerial view of a desert with a huge number of satellite dishes." src="https://images.theconversation.com/files/490932/original/file-20221020-1690-8mwnqz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/490932/original/file-20221020-1690-8mwnqz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=328&fit=crop&dpr=1 600w, https://images.theconversation.com/files/490932/original/file-20221020-1690-8mwnqz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=328&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/490932/original/file-20221020-1690-8mwnqz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=328&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/490932/original/file-20221020-1690-8mwnqz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=412&fit=crop&dpr=1 754w, https://images.theconversation.com/files/490932/original/file-20221020-1690-8mwnqz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=412&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/490932/original/file-20221020-1690-8mwnqz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=412&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This artist’s impression shows the Square Kilometer Array, a telescope array currently being built in both Australia and Africa that will be sensitive enough to detect the equivalent of radio broadcasts from distant planets.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:SKA_overview.jpg#/media/File:SKA_overview.jpg">SPDO/TDP/DRAO/Swinburne Astronomy Productions/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<h2>Leaking radio waves</h2>
<p>Though humans don’t transmit many intentional signals out to the cosmos, many technologies people use today produce a lot of radio transmissions that leak into space. Some of these signals would be detectable if they came from a nearby star.</p>
<p>The worldwide network of television towers constantly emits signals in many directions that leak into space and can <a href="https://doi.org/10.1126/science.199.4327.377">accumulate into a detectable, though relatively faint</a>, radio signal. Research is ongoing as to whether current emissions from cell towers in the radio frequency on Earth would be detectable using today’s telescopes, but the upcoming <a href="https://doi.org/10.1088/1475-7516/2007/01/020">Square Kilometer Array radio telescope will be able to detect</a> even fainter radio signals with <a href="https://theconversation.com/the-science-behind-the-square-kilometre-array-40870">50 times the sensitivity of current radio telescope arrays</a>. </p>
<p>Not all human-made signals are so unfocused, though. Astronomers and space agencies use beams of radio waves to communicate with <a href="https://www.nasa.gov/directorates/heo/scan/services/networks/deep_space_network/about">satellites and space craft</a> in the solar system. Some researchers also use radio waves for <a href="https://www.nasa.gov/feature/jpl/planetary-radar-observes-1000th-near-earth-asteroid-since-1968">radar to study asteroids</a>. In both of these cases, the radio signals are more focused and pointed out into space. Any extraterrestrial civilization that happened to be in the line of sight of these beams could likely detect these unambiguously artificial signals.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/490926/original/file-20221020-18-l76626.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A rendering of a massive set of rings around a star in space." src="https://images.theconversation.com/files/490926/original/file-20221020-18-l76626.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/490926/original/file-20221020-18-l76626.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/490926/original/file-20221020-18-l76626.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/490926/original/file-20221020-18-l76626.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/490926/original/file-20221020-18-l76626.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/490926/original/file-20221020-18-l76626.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/490926/original/file-20221020-18-l76626.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A Dyson Sphere is a theoretical megastructure that would surround a star and collect its light to use as energy.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/kevinmgill/29401385502/">Kevin Gill/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
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<h2>Finding megastructures</h2>
<p>Aside from finding an actual alien spacecraft, radio waves are the most common technosignatures featured in sci-fi movies and books. But they are not the only signals that could be out there.</p>
<p>In 1960, astronomer Freeman Dyson theorized that, since stars are by far the most powerful energy source in any planetary system, a technologically advanced civilization might <a href="https://doi.org/10.1088/10.1126/science.131.3414.1667">collect a significant portion of the star’s light as energy</a> with what would essentially be a massive solar panel. Many astronomers call these megastructures, and there are a few ways to detect them.</p>
<p>After using the energy in the captured light, the technology of an advanced society would <a href="https://stem.guide/topic/entropy-the-second-law-of-thermodynamics/">re-emit some of the energy as heat</a>. Astronomers have shown that this heat <a href="https://ui.adsabs.harvard.edu/abs/1966ApJ...144.1216S/abstract">could be detectable</a> as extra infrared radiation coming from a star system.</p>
<p>Another possible way to find a megastructure would be to <a href="https://theconversation.com/what-are-the-odds-of-an-alien-megastructure-blocking-light-from-a-distant-star-49311">measure its dimming effect on a star</a>. Specifically, large artificial satellites orbiting a star would periodically block some of its light. This would appear as dips in the star’s apparent brightness over time. Astronomers could detect this effect similarly to how <a href="https://theconversation.com/are-there-any-planets-outside-of-our-solar-system-164062">distant planets are discovered today</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/490924/original/file-20221020-13-90h06v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An artist's depiction of a planet covered in cities and with a chemically altered atmosphere." src="https://images.theconversation.com/files/490924/original/file-20221020-13-90h06v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/490924/original/file-20221020-13-90h06v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=495&fit=crop&dpr=1 600w, https://images.theconversation.com/files/490924/original/file-20221020-13-90h06v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=495&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/490924/original/file-20221020-13-90h06v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=495&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/490924/original/file-20221020-13-90h06v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=622&fit=crop&dpr=1 754w, https://images.theconversation.com/files/490924/original/file-20221020-13-90h06v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=622&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/490924/original/file-20221020-13-90h06v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=622&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Advanced civilizations may produce a lot of pollution in the form of chemicals, light and heat that can be detected across the vast distances of space.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/press-release/goddard/2021/technosignature">NASA/Jay Freidlander</a></span>
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<h2>A whole lot of pollution</h2>
<p>Another technosignature that astronomers have thought about is pollution.</p>
<p>Chemical pollutants – like <a href="https://www.nasa.gov/press-release/goddard/2021/technosignature">nitrogen dioxide</a> and <a href="https://doi.org/10.3847/PSJ/ac5404">chlorofluorocarbons</a> on Earth are almost exclusively produced by human industry. It is possible to detect these molecules in the <a href="https://theconversation.com/its-all-in-the-atmosphere-exploring-planets-orbiting-distant-stars-62034">atmospheres of exoplanets</a> with the same method the James Webb Space Telescope is using to <a href="https://theconversation.com/to-search-for-alien-life-astronomers-will-look-for-clues-in-the-atmospheres-of-distant-planets-and-the-james-webb-space-telescope-just-proved-its-possible-to-do-so-184828">search distant planets for signs of biology</a>. If astronomers find a planet with an atmosphere filled with chemicals that can only be produced by technology, it may be a sign of life.</p>
<p>Finally, <a href="https://doi.org/10.1093/mnras/stac469">artificial light</a> or <a href="https://doi.org/10.1017/S1473550414000585">heat from cities and industry</a> could also be detectable with large optical and infrared telescopes, as would a large <a href="https://doi.org/10.3847/1538-4357/aaae66">number of satellites orbiting a planet</a>. But a civilization would need to produce far more heat, light and satellites than Earth does to be detectable across the vastness of space using technology humans currently possess.</p>
<h2>Which signal is best?</h2>
<p>No astronomer has ever found a confirmed technosignature, so it’s hard to say what will be the first sign of alien civilizations. While many astronomers have thought a lot about <a href="https://doi.org/10.1017/S1473550419000284">what might make for a good signal</a>,
ultimately, nobody knows what extraterrestrial technology might look like and what signals are out there in the Universe. </p>
<p>Some astronomers support a <a href="https://www.aspbooks.org/publications/213/519.pdf">generalized SETI</a> approach which searches for anything in space that current scientific knowledge cannot naturally explain. Some, like us, continue to search for both intentional and unintentional technosignatures. The bottom line is that there are many avenues for detecting distant life. Since no one knows what approach is likely to succeed first, there is still a lot of exciting work left to do.</p><img src="https://counter.theconversation.com/content/191054/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jason Wright does research supported by the Penn State Extraterrestrial Intelligence Center. He also does SETI research and runs conferences dedicated to SETI with funds from NASA and the NSF.</span></em></p><p class="fine-print"><em><span>Macy Huston does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
The technology of an advanced alien civilization is likely to produce many signs that could be detected across the vastness of space. Two astronomers explain the search for technosignatures.
Macy Huston, PhD Candidate in Astronomy and Astrophysics, Penn State
Jason Wright, Professor of Astronomy and Astrophysics, Penn State
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/161811
2021-06-13T20:07:22Z
2021-06-13T20:07:22Z
Do aliens exist? We asked five experts
<figure><img src="https://images.theconversation.com/files/405853/original/file-20210611-17-1fcr2df.jpg?ixlib=rb-1.1.0&rect=170%2C89%2C5793%2C3880&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Speculation has been rife about the contents of an unclassified report set to be released later this month from the Pentagon’s Unidentified Aerial Phenomena (UAP) task force. </p>
<p>The document, <a href="https://www.scientificamerican.com/article/experts-weigh-in-on-pentagon-ufo-report/">expected to drop</a> on June 25, will supposedly provide a comprehensive summary of what the US government knows about UAPs — or, to use the more popular term, UFOs.</p>
<p>While the report is not yet public, the New York Times recently <a href="https://www.nytimes.com/2021/06/03/us/politics/ufos-sighting-alien-spacecraft-pentagon.html">published</a> what it claimed was a preview of the findings, provided by unnamed senior officials who were privy to the report’s contents. </p>
<p>According to the Times’s sources, the report does not provide any clear link or association between more than 120 incidents of UFO sightings from the past two decades, and a possibility of Earth having been visited by aliens.</p>
<p>If the Times’s sources are to be believed, there’s clearly still no good reason to interpret an unexplained object in the sky as evidence of aliens. But does that mean aliens aren’t out there, somewhere else in the universe? And if they are, could we ever find them? Or might they be so different to us that “finding” them is impossible in any meaningful sense?</p>
<p>We asked five experts. </p>
<h2>Four out of five experts said aliens do exist</h2>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/315871/original/file-20200218-11005-1x9b2hg.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/315871/original/file-20200218-11005-1x9b2hg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/315871/original/file-20200218-11005-1x9b2hg.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=99&fit=crop&dpr=1 600w, https://images.theconversation.com/files/315871/original/file-20200218-11005-1x9b2hg.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=99&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/315871/original/file-20200218-11005-1x9b2hg.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=99&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/315871/original/file-20200218-11005-1x9b2hg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=125&fit=crop&dpr=1 754w, https://images.theconversation.com/files/315871/original/file-20200218-11005-1x9b2hg.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=125&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/315871/original/file-20200218-11005-1x9b2hg.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=125&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<p><strong>Here are their detailed responses:</strong></p>
<p><iframe id="tc-infographic-587" class="tc-infographic" height="400px" src="https://cdn.theconversation.com/infographics/587/04f8cf2f024c65ae2010dc729c28c7600cecda2d/site/index.html" width="100%" style="border: none" frameborder="0"></iframe></p>
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Read more:
<a href="https://theconversation.com/the-us-military-has-officially-published-three-ufo-videos-why-doesnt-anybody-seem-to-care-137498">The US military has officially published three UFO videos. Why doesn't anybody seem to care?</a>
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</em>
</p>
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<img src="https://counter.theconversation.com/content/161811/count.gif" alt="The Conversation" width="1" height="1" />
Even if aliens exist, are intelligent like humans and interested in making contact with us, what are the chances they’ll be close enough for us to hear them screaming their presence into the cosmos?
Noor Gillani, Digital Culture Editor
Chynthia Wijaya-Kovac, Social Media Producer, The Conversation Australia
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/120193
2019-08-07T15:05:56Z
2019-08-07T15:05:56Z
The end of the world: a history of how a silent cosmos led humans to fear the worst
<figure><img src="https://images.theconversation.com/files/287162/original/file-20190807-144851-1f9em60.jpg?ixlib=rb-1.1.0&rect=0%2C682%2C3000%2C2034&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/a/a8/NASA-Apollo8-Dec24-Earthrise.jpg">NASA</a></span></figcaption></figure><p>It is 1950 and a group of scientists <a href="https://fas.org/sgp/othergov/doe/lanl/la-10311-ms.pdf">are walking to lunch</a> against the majestic backdrop of the Rocky Mountains. They are about to have a conversation that will become scientific legend. The scientists are at the Los Alamos Ranch School, the site for <a href="https://theconversation.com/how-american-journalists-covered-the-first-use-of-the-atomic-bomb-45746">the Manhattan Project</a>, where each of the group has lately played their part in ushering in the atomic age.</p>
<p>They are laughing about a <a href="https://fas.org/sgp/othergov/doe/lanl/la-10311-ms.pdf">recent cartoon</a> in the New Yorker offering an unlikely explanation for a slew of missing public trash cans across New York City. The cartoon had depicted “little green men” (complete with antenna and guileless smiles) having stolen the bins, assiduously unloading them from their flying saucer.</p>
<p>By the time the party of nuclear scientists sits down to lunch, within the mess hall of a grand log cabin, one of their number turns the conversation to matters more serious. “Where, then, is everybody?”, he asks. They all know that he is talking – sincerely – about extraterrestrials.</p>
<p>The question, which was posed by <a href="https://archive.nytimes.com/www.nytimes.com/learning/general/onthisday/bday/0929.html">Enrico Fermi</a> and is now known as <a href="https://www.space.com/25325-fermi-paradox.html">Fermi’s Paradox</a>, has chilling implications.</p>
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<p>Bin-stealing UFOs notwithstanding, humanity still hasn’t found any evidence of intelligent activity among the stars. Not a single feat of “<a href="https://www.fossilhunters.xyz/intelligent-extraterrestrials/astroengineering-and-supercivilizations.html">astro-engineering</a>”, no visible superstructures, not one space-faring empire, not even a radio transmission. It <a href="https://nickbostrom.com/extraterrestrial.pdf">has been</a> <a href="http://mason.gmu.edu/%7Erhanson/greatfilter.html">argued</a> that the eerie silence from the sky above may well tell us something ominous about the future course of our own civilisation.</p>
<p>Such fears are ramping up. Last year, the astrophysicist Adam Frank implored <a href="https://youtu.be/rPY6N_qqAaE">an audience at Google</a> that we see climate change – and the newly baptised geological age of the <a href="https://theconversation.com/uk/topics/anthropocene-2770">Anthropocene</a> – against this cosmological backdrop. The Anthropocene refers to the effects of humanity’s energy-intensive activities upon Earth. Could it be that we do not see evidence of space-faring galactic civilisations because, due to resource exhaustion and subsequent climate collapse, none of them ever get that far? If so, why should we be any different?</p>
<p>A few months after Frank’s talk, in October 2018, the Intergovernmental Panel on Climate Change’s <a href="https://report.ipcc.ch/sr15/pdf/sr15_spm_final.pdf">update on global warming</a> caused a stir. It predicted a sombre future if we do not decarbonise. And in May, amid Extinction Rebellion’s protests, a <a href="https://docs.wixstatic.com/ugd/148cb0_90dc2a2637f348edae45943a88da04d4.pdf">new climate report</a> upped the ante, warning: “Human life on earth may be on the way to extinction.”</p>
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<p><em><strong>This article is part of Conversation Insights</strong></em></p>
<p><em>The Conversation’s <a href="https://theconversation.com/introducing-conversation-insights-a-new-team-that-seeks-scoops-from-interdisciplinary-research-107119">Insights team</a> generates long-form journalism derived from interdisciplinary research. The team is working with academics from different backgrounds who have been engaged in projects aimed at tackling societal and scientific challenges. In generating these narratives, we hope to bring areas of interdisciplinary research to a wider audience.</em></p>
<p><em>You can read more Insights stories <a href="https://theconversation.com/uk/topics/insights-series-71218">here</a>.</em></p>
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<p>Meanwhile, NASA has been <a href="https://cneos.jpl.nasa.gov/pd/cs/pdc19/pdc19_pr5.pdf">publishing press releases</a> about an asteroid set to hit New York within a month. This is, of course, a dress rehearsal: part of a “stress test” designed to simulate responses to such a catastrophe. NASA is obviously fairly worried by the prospect of such a disaster event – such simulations are costly.</p>
<p>Space tech Elon Musk has also been relaying <a href="https://twitter.com/elonmusk/status/495759307346952192?lang=en">his fears</a> about artificial intelligence to YouTube audiences of tens of millions. He and others worry that the ability for AI systems to rewrite and self-improve themselves may trigger a sudden runaway process, or “<a href="https://intelligence.org/ie-faq/#r13">intelligence explosion</a>”, that will leave us far behind – an artificial superintelligence need not even be intentionally malicious in order to <a href="https://en.wikipedia.org/wiki/Instrumental_convergence">accidentally wipe us out</a>. </p>
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<p>In 2015, Musk <a href="https://www.fhi.ox.ac.uk/elon-musk-funds-oxford-and-cambridge-university-research-on-safe-and-beneficial-artificial-intelligence/">donated to</a> Oxford’s Future of Humanity Institute, headed up by transhumanist Nick Bostrom. Nestled within the university’s medieval spires, Bostrom’s institute scrutinises the long-term fate of humanity and the perils we face at a truly cosmic scale, <a href="https://books.google.co.uk/books?id=sTkfAQAAQBAJ&printsec=frontcover">examining the risks</a> of things such as climate, asteroids and AI. It also looks into less well-publicised issues. Universe destroying physics experiments, gamma-ray bursts, planet-consuming nanotechnology and exploding supernovae have all come under its gaze.</p>
<p>So it would seem that humanity is becoming more and more concerned with portents of human extinction. As a global community, we are increasingly conversant with increasingly severe futures. Something is in the air. </p>
<p>But this tendency is not actually exclusive to the post-atomic age: our growing concern about extinction has a history. We have been becoming more and more worried for our future for quite some time now. My PhD research tells the story of how this began. No one has yet told this story, yet I feel it is an important one for our present moment.</p>
<p>I wanted to find out how current projects, such as the Future of Humanity Institute, emerge as offshoots and continuations of an ongoing project of “enlightenment” that we first set ourselves over two centuries ago. Recalling how we first came to care for our future helps reaffirm why we should continue to care today.</p>
<h2>Extinction, 200 years ago</h2>
<p>In 1816, something was also in the air. It was a 100-megaton sulfate aerosol layer. Girdling the planet, it was made up of material thrown into the stratosphere by the eruption of <a href="https://theconversation.com/why-a-volcano-frankenstein-and-the-summer-of-1816-are-relevant-to-the-anthropocene-64984">Mount Tambora</a>, in Indonesia, the previous year. It was one of the <a href="https://books.google.co.uk/books?id=uW2YDwAAQBAJ&source=gbs_navlinks_s">biggest volcanic eruptions</a> since civilisation emerged during the <a href="https://theconversation.com/uk/topics/holocene-4976">Holocene</a>.</p>
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<img alt="" src="https://images.theconversation.com/files/284861/original/file-20190718-116586-14l924k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/284861/original/file-20190718-116586-14l924k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/284861/original/file-20190718-116586-14l924k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/284861/original/file-20190718-116586-14l924k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/284861/original/file-20190718-116586-14l924k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/284861/original/file-20190718-116586-14l924k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/284861/original/file-20190718-116586-14l924k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Mount Tambora’s crater.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Mount_Tambora_Volcano,_Sumbawa_Island,_Indonesia.jpg">Wikimedia Commons/NASA</a></span>
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<p>Almost blotting out the sun, Tambora’s fallout caused a global cascade of harvest collapse, mass famine, cholera outbreak and geopolitical instability. And it also provoked the first popular fictional depictions of human extinction. These came from a <a href="https://en.wikipedia.org/wiki/Satanic_School">troupe of writers</a> including <a href="https://theconversation.com/uk/topics/lord-byron-17950">Lord Byron</a>, <a href="https://theconversation.com/uk/topics/mary-shelley-43620">Mary Shelley</a> and <a href="https://theconversation.com/uk/topics/percy-shelley-50539">Percy Shelley</a>.</p>
<p>The group had been holidaying together in Switzerland when titanic thunderstorms, caused by Tambora’s climate perturbations, trapped them inside their villa. Here <a href="https://books.google.co.uk/books?id=s3hPAQAAMAAJ&pg=PA429&lpg=PA429&dq=%22what+a+change+it+would+be+if+the%22&source=bl&ots=9uPYGYSrNH&sig=ACfU3U1Y7qLT7Ek8K54nHKDxik5AEIep2Q&hl=en&sa=X&ved=2ahUKEwioytS57r7jAhUDolwKHf-yBoQQ6AEwAHoECAEQAQ#v=onepage&q=%22what%20a%20change%20it%20would%20be%20if%20the%22&f=false">they discussed</a> humanity’s long-term prospects.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/why-a-volcano-frankenstein-and-the-summer-of-1816-are-relevant-to-the-anthropocene-64984">Why a volcano, Frankenstein, and the summer of 1816 are relevant to the Anthropocene</a>
</strong>
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<p>Clearly inspired by these conversations and by 1816’s hellish weather, Byron immediately set to work on a poem entitled “<a href="https://www.poetryfoundation.org/poems/43825/darkness-56d222aeeee1b">Darkness</a>”. It imagines what would happen if our sun died:</p>
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<p>I had a dream, which was not all a dream<br>
The bright sun was extinguish’d, and the stars<br>
Did wander darkling in the eternal space<br>
Rayless, and pathless, and the icy earth<br>
Swung blind and blackening in the moonless air </p>
</blockquote>
<p>Detailing the ensuing sterilisation of our biosphere, it caused a stir. And almost 150 years later, against the backdrop of escalating Cold War tensions, the Bulletin for Atomic Scientists again <a href="https://books.google.co.uk/books?id=rQYAAAAAMBAJ&pg=PA37&dq=%22a+soviet+view+of+nuclear+winter%22&hl=en&sa=X&ved=0ahUKEwjf3ZzK4rzjAhXVQkEAHYaVCDYQ6AEIMDAB#v=onepage&q=%22a%20soviet%20view%20of%20nuclear%20winter%22&f=false">called upon</a> Byron’s poem to illustrate the severity of nuclear winter.</p>
<p>Two years later, Mary Shelley’s <a href="https://theconversation.com/eight-things-you-need-to-know-about-mary-shelleys-frankenstein-93030">Frankenstein</a> (perhaps the first book on synthetic biology) refers to the potential for the lab-born monster to outbreed and exterminate <em>Homo sapiens</em> as a competing species. By 1826, Mary went on to publish <a href="https://www.gutenberg.org/ebooks/18247">The Last Man</a>. This was the first full-length novel on human extinction, depicted here at the hands of pandemic pathogen.</p>
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<img alt="" src="https://images.theconversation.com/files/286253/original/file-20190730-186833-1bjz1d1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/286253/original/file-20190730-186833-1bjz1d1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=753&fit=crop&dpr=1 600w, https://images.theconversation.com/files/286253/original/file-20190730-186833-1bjz1d1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=753&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/286253/original/file-20190730-186833-1bjz1d1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=753&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/286253/original/file-20190730-186833-1bjz1d1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=947&fit=crop&dpr=1 754w, https://images.theconversation.com/files/286253/original/file-20190730-186833-1bjz1d1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=947&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/286253/original/file-20190730-186833-1bjz1d1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=947&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Boris Karloff plays Frankenstein’s monster, 1935.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:Frankenstein%27s_monster_(Boris_Karloff).jpg#/media/File:Frankenstein's_monster_(Boris_Karloff).jpg">Wikimedia Commons</a></span>
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<p>Beyond these speculative fictions, other writers and thinkers had already discussed such threats. Samuel Taylor Coleridge, <a href="https://en.wikipedia.org/wiki/Great_Comet_of_1811">in 1811</a>, daydreamed in his private notebooks about our planet being “scorched by a close comet and still rolling on – cities men-less, channels riverless, five mile deep”. In 1798, Mary Shelley’s father, the political thinker William Godwin, <a href="https://books.google.co.uk/books?id=zx5nAAAAcAAJ&pg=PA453&dq=william+godwin+enquiry+%22will+it+continue+for+ever%22&hl=en&sa=X&ved=0ahUKEwjTooeV7L7jAhWLN8AKHQHGDqcQ6AEIKjAA#v=onepage&q=william%20godwin%20enquiry%20%22will%20it%20continue%20for%20ever%22&f=false">queried</a> whether our species would “continue forever”?</p>
<p>While just a few years earlier, Immanuel Kant had <a href="https://books.google.co.uk/books?id=0hCsbUjFiBwC&pg=PA320&dq=kant+%22only+in+the+vast+graveyard+of+the+human+race%22&hl=en&sa=X&ved=0ahUKEwj-g6mr7L7jAhWMiFwKHQSaBMoQ6AEINjAC#v=onepage&q=kant%20%22only%20in%20the%20vast%20graveyard%20of%20the%20human%20race%22&f=false">pessimistically proclaimed</a> that global peace may be achieved “only in the vast graveyard of the human race”. He would, soon after, <a href="https://books.google.co.uk/books?id=pJWKGVPjRbIC&pg=PA66&dq=%22exist+for+the+sake+of+others+of+a+different+species%22+opus+postumum&hl=en&sa=X&ved=0ahUKEwi6iJve7L7jAhWwQUEAHRXkCEAQ6AEIKjAA#v=onepage&q=%22exist%20for%20the%20sake%20of%20others%20of%20a%20different%20species%22%20opus%20postumum&f=false">worry about</a> a descendent offshoot of humanity becoming more intelligent and pushing us aside. </p>
<p>Earlier still, in 1754, philosopher David Hume had <a href="https://books.google.co.uk/books?id=W00DP4Lx0BgC&pg=PA108&dq=hume+%22man,+equally+with+every+animal+and+vegetable%22&hl=en&sa=X&ved=0ahUKEwjW1e7p7L7jAhWMh1wKHfBgAjEQ6AEITDAG#v=onepage&q=hume%20%22man%2C%20equally%20with%20every%20animal%20and%20vegetable%22&f=false">declared that</a> “man, equally with every animal and vegetable, will partake” in extinction. Godwin <a href="https://books.google.co.uk/books?id=5HzQAAdx6DsC&pg=PA445&dq=godwin+%22some+of+the+profoundest+enquirers%22&hl=en&sa=X&ved=0ahUKEwjFya357L7jAhVOfMAKHfYbDAUQ6AEILDAA#v=onepage&q=godwin%20%22some%20of%20the%20profoundest%20enquirers%22&f=false">noted</a> that “some of the profoundest enquirers” had lately become concerned with “the extinction of our species”. </p>
<p>In 1816, against the backdrop of <a href="https://www.atmos-chem-phys.net/7/4027/2007/acp-7-4027-2007.pdf">Tambora’s glowering skies</a>, a <a href="https://books.google.co.uk/books?id=Cio8AQAAMAAJ&pg=PA209&dq=%22here,+then,+is+a+very+rational+end+of+the+world%22&hl=en&sa=X&ved=0ahUKEwjipfmJ7b7jAhUJT8AKHYDtByEQ6AEIKjAA#v=onepage&q=%22here%2C%20then%2C%20is%20a%20very%20rational%20end%20of%20the%20world%22&f=false">newspaper article</a> drew attention to this growing murmur. It listed numerous extinction threats. From global refrigeration to rising oceans to planetary conflagration, it spotlighted the new scientific concern for human extinction. The “probability of such a disaster is daily increasing”, the article glibly noted. Not without chagrin, it closed by stating: “Here, then, is a very rational end of the world!”</p>
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<img alt="" src="https://images.theconversation.com/files/286249/original/file-20190730-186824-j0wlfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/286249/original/file-20190730-186824-j0wlfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=489&fit=crop&dpr=1 600w, https://images.theconversation.com/files/286249/original/file-20190730-186824-j0wlfs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=489&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/286249/original/file-20190730-186824-j0wlfs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=489&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/286249/original/file-20190730-186824-j0wlfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=615&fit=crop&dpr=1 754w, https://images.theconversation.com/files/286249/original/file-20190730-186824-j0wlfs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=615&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/286249/original/file-20190730-186824-j0wlfs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=615&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Tambora’s dust-cloud created ominous sunsets, such as this one painted by Turner, c. 1830–5.</span>
<span class="attribution"><a class="source" href="https://www.tate.org.uk/art/artworks/turner-sunset-n01876">© Tate</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
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<h2>Before this, we thought the universe was busy</h2>
<p>So if people first started worrying about human extinction in the 18th century, where was the notion beforehand? There is enough apocalypse in scripture to last until judgement day, surely. But extinction has nothing to do with apocalypse. The two ideas are utterly different, even contradictory.</p>
<p>For a start, apocalyptic prophecies are designed to reveal the ultimate moral meaning of things. It’s in the name: apocalypse means revelation. Extinction, by direct contrast, reveals precisely nothing and this is because it instead predicts the end of meaning and morality itself – if there are no humans, there is nothing humanly meaningful left.</p>
<p>And this is precisely why extinction <a href="https://docs.wixstatic.com/ugd/d9aaad_7aa94f824f41463dbc55e24e321c4731.pdf">matters</a>. Judgement day allows us to feel comfortable knowing that, in the end, the universe is ultimately in tune with what we call “justice”. Nothing was ever truly at stake. On the other hand, extinction alerts us to the fact that everything we hold dear has always been in jeopardy. In other words, everything is at stake.</p>
<p>Extinction was not much discussed before 1700 due to a background assumption, widespread prior to the Enlightenment, that it is the nature of the cosmos to be as full as moral value and worth as is possible. This, in turn, led people to assume that all other planets are populated with “<a href="https://books.google.co.uk/books?id=VGoFAAAAQAAJ&pg=PR7&dq=%22living+and+thinking+beings%22+lalande&hl=en&sa=X&ved=0ahUKEwi_r7Oh5LzjAhWRT8AKHbsgA1AQ6AEINTAC#v=onepage&q=%22living%20and%20thinking%20beings%22%20lalande&f=false">living and thinking beings</a>” exactly like us. </p>
<p>Although it only became a truly widely accepted fact after Copernicus and Kepler in the 16th and 17th centuries, the idea of plural worlds certainly dates back to antiquity, with intellectuals <a href="https://books.google.it/books?id=Ygc5AAAAIAAJ&printsec=frontcover&hl=it">from Epicurus to Nicholas of Cusa</a> proposing them to be inhabited with lifeforms similar to our own. And, in a cosmos that is infinitely populated with humanoid beings, such beings – and their values – can never fully go extinct.</p>
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<img alt="" src="https://images.theconversation.com/files/286254/original/file-20190730-186833-4c3aqj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/286254/original/file-20190730-186833-4c3aqj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=466&fit=crop&dpr=1 600w, https://images.theconversation.com/files/286254/original/file-20190730-186833-4c3aqj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=466&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/286254/original/file-20190730-186833-4c3aqj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=466&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/286254/original/file-20190730-186833-4c3aqj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=586&fit=crop&dpr=1 754w, https://images.theconversation.com/files/286254/original/file-20190730-186833-4c3aqj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=586&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/286254/original/file-20190730-186833-4c3aqj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=586&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Star cluster Messier 13 in Hercules, 1877.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Trouvelot_-_Star_clusters_in_Hercules_-_1877.jpg">Wikimedia Commons</a></span>
</figcaption>
</figure>
<p>In the 1660s, Galileo <a href="https://books.google.co.uk/books?id=saEwDwAAQBAJ&pg=PA58&lpg=PA58&dq=%22useless+lump+in+the+universe%22&source=bl&ots=3WFYe5eQL5&sig=ACfU3U3DS2hE1Dv3PJ39kHVRN3pFUNRUjg&hl=en&sa=X&ved=2ahUKEwjxgKmr9L7jAhUjTxUIHe1sCL0Q6AEwAnoECAQQAQ#v=onepage&q=%22useless%20lump%20in%20the%20universe%22&f=false">confidently declared</a> that an entirely uninhabited or unpopulated world is “naturally impossible” on account of it being “morally unjustifiable”. Gottfried Leibniz later <a href="https://books.google.co.uk/books?id=fT7KAgAAQBAJ&pg=PA26&dq=%22fallow,+sterile,+or+dead+in+the+universe%22+monadology&hl=en&sa=X&ved=0ahUKEwjR49fd8r7jAhWaiVwKHTepBHEQ6AEIMDAB#v=onepage&q=%22fallow%2C%20sterile%2C%20or%20dead%20in%20the%20universe%22%20monadology&f=false">pronounced</a> that there simply cannot be anything entirely “fallow, sterile, or dead in the universe”.</p>
<p>Along the same lines, the trailblazing scientist Edmond Halley (after whom the famous comet is named) <a href="https://archive.org/details/philtrans00697664/page/n15">reasoned</a> in 1753 that the interior of our planet must likewise be “inhabited”. It would be “unjust” for any part of nature to be left “unoccupied” by moral beings, he argued. </p>
<p>Around the same time Halley provided <a href="https://royalsocietypublishing.org/doi/pdf/10.1098/rstl.1724.0023">the first theory</a> on a “mass extinction event”. He speculated that comets had previously wiped out entire “worlds” of species. Nonetheless, he also maintained that, after each previous cataclysm “human civilisation had reliably re-emerged”. And it would do so again. Only this, <a href="https://royalsocietypublishing.org/doi/pdf/10.1098/rstl.1724.0024">he said</a> could make such an event morally justifiable.</p>
<p>Later, in the 1760s, the philosopher Denis Diderot was <a href="https://books.google.co.uk/books?id=m_l9BgAAQBAJ&pg=PA99&lpg=PA99&dq=%22biped+animal+who+carries+the+name+man%22&source=bl&ots=qy2MMsHghS&sig=ACfU3U2uWt0WXC1N6KKoQHiFPUh4L9Ojog&hl=en&sa=X&ved=2ahUKEwj3u-jo8b7jAhUyrHEKHXA-BFUQ6AEwAHoECAAQAQ#v=onepage&q=%22biped%20animal%20who%20carries%20the%20name%20man%22&f=false">attending a dinner party</a> when he was asked whether humans would go extinct. He answered “yes”, but immediately qualified this by saying that after several millions of years the “biped animal who carries the name man” would inevitably re-evolve.</p>
<p>This is what the contemporary planetary scientist Charles Lineweaver identifies as the “<a href="https://arxiv.org/ftp/arxiv/papers/0711/0711.1751.pdf">Planet of the Apes Hypothesis</a>”. This refers to the misguided presumption that “human-like intelligence” is a recurrent feature of cosmic evolution: that alien biospheres will reliably produce beings like us. This is what is behind the <a href="https://books.google.co.uk/books?id=sTkfAQAAQBAJ&pg=PA8&lpg=PA8&dq=%22there+is+no+guarantee+that+a+rerun+of+evolution%22&source=bl&ots=z2hc748GoH&sig=ACfU3U2_zEbLku-j4CMzkpJUCDN_ARa52A&hl=en&sa=X&ved=2ahUKEwizopva8L7jAhU1sXEKHZgqB_EQ6AEwAHoECAQQAQ#v=onepage&q=%22there%20is%20no%20guarantee%20that%20a%20rerun%20of%20evolution%22&f=false">wrong-headed</a> assumption that, should we be wiped out today, something like us will inevitably return tomorrow.</p>
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<p>Back in Diderot’s time, this assumption was pretty much the only game in town. It was why one British astronomer <a href="https://books.google.co.uk/books?id=80VZAAAAcAAJ&pg=PA76&dq=%22Mortality+with+us+upon+the+Earth%22&hl=en&sa=X&ved=0ahUKEwjMkf6C-L7jAhU7URUIHfBPA8MQ6AEIMDAB#v=onepage&q=%22Mortality%20with%20us%20upon%20the%20Earth%22&f=false">wrote</a>, in 1750, that the destruction of our planet would matter as little as “Birth-Days or Mortalities” do down on Earth.</p>
<p>This was typical thinking at the time. Within the prevailing worldview of eternally returning humanoids throughout an infinitely populated universe, there was simply no pressure or need to care for the future. Human extinction simply couldn’t matter. It was trivialised to the point of being unthinkable.</p>
<p>For the same reasons, the idea of the “future” was also missing. People simply didn’t care about it in the way we do now. Without the urgency of a future riddled with risk, there was no motivation to be interested in it, let alone attempt to predict and preempt it.</p>
<p>It was the dismantling of such dogmas, beginning in the 1700s and ramping up in the 1800s, that set the stage for the enunciation of Fermi’s Paradox in the 1900s and leads to our growing appreciation for our cosmic precariousness today.</p>
<h2>But then we realised the skies are silent</h2>
<p>In order to truly care about our mutable position down here, we first had to notice that the cosmic skies above us are crushingly silent. Slowly at first, though soon after gaining momentum, this realisation began to take hold around the same time that Diderot had his dinner party.</p>
<p>One of the first examples of a different mode of thinking I’ve found is from 1750, when the French polymath Claude-Nicholas Le Cat wrote a history of the earth. Like Halley, he posited the now familiar cycles of “ruin and renovation”. Unlike Halley, he was conspicuously unclear as to whether humans would return after the next cataclysm. A shocked reviewer picked up on this, <a href="https://books.google.co.uk/books?id=me9dAAAAcAAJ&pg=PA384&dq=%22earth+shall+be+re-peopled%22&hl=en&sa=X&ved=0ahUKEwiinqKY-L7jAhUzQhUIHUhSA2kQ6AEIKjAA#v=onepage&q=%22earth%20shall%20be%20re-peopled%22&f=false">demanding</a> to know whether “Earth shall be re-peopled with new inhabitants”. In reply, the author facetiously <a href="https://books.google.co.uk/books?id=me9dAAAAcAAJ&pg=PA388&dq=%22gratify+the+curiosity+of+the+new+inhabitants+of+the+new+world%22&hl=en&sa=X&ved=0ahUKEwjFgpyq-L7jAhUgXhUIHZcwBlEQ6AEIKjAA#v=onepage&q=%22gratify%20the%20curiosity%20of%20the%20new%20inhabitants%20of%20the%20new%20world%22&f=false">asserted</a> that our fossil remains would “gratify the curiosity of the new inhabitants of the new world, if there be any”. The cycle of eternally returning humanoids was unwinding.</p>
<p>In line with this, the French encyclopaedist Baron d’Holbach <a href="https://books.google.co.uk/books?id=W1e4H6A-XQIC&pg=PA146&dq=d%27holbach+%22inhabited+by+beings+resembling+ourselves%22&hl=en&sa=X&ved=0ahUKEwickcfR-L7jAhVFsXEKHc8xAWcQ6AEIKjAA#v=onepage&q=d'holbach%20%22inhabited%20by%20beings%20resembling%20ourselves%22&f=false">ridiculed</a> the “conjecture that other planets, like our own, are inhabited by beings resembling ourselves”. He <a href="https://books.google.co.uk/books?id=W1e4H6A-XQIC&pg=PA145&dq=d%27holbach+%22obliged+to+disappear%22&hl=en&sa=X&ved=0ahUKEwi40ZTw-L7jAhXJh1wKHVd1DRQQ6AEIMDAB#v=onepage&q=d'holbach%20%22obliged%20to%20disappear%22&f=false">noted</a> that precisely this dogma – and the related belief that the cosmos is inherently full of moral value – had long obstructed appreciation that the human species could permanently “disappear” from existence. By 1830, the German philosopher F W J Schelling <a href="https://books.google.co.uk/books?id=hu4GAAAAcAAJ&pg=RA1-PA312&dq=berall+menschen%C3%A4hnliche+Wesen+verbreitet+und+letzter+Zweck+seyn+sollen&hl=en&sa=X&ved=0ahUKEwiahp6G-b7jAhXUNcAKHXvbDw0Q6AEIYTAH#v=onepage&q=berall%20menschen%C3%A4hnliche%20Wesen%20verbreitet%20und%20letzter%20Zweck%20seyn%20sollen&f=false">declared</a> it utterly naive to go on presuming “that humanoid beings are found everywhere and are the ultimate end”.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/286269/original/file-20190730-186809-4g43jx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/286269/original/file-20190730-186809-4g43jx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=556&fit=crop&dpr=1 600w, https://images.theconversation.com/files/286269/original/file-20190730-186809-4g43jx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=556&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/286269/original/file-20190730-186809-4g43jx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=556&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/286269/original/file-20190730-186809-4g43jx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=698&fit=crop&dpr=1 754w, https://images.theconversation.com/files/286269/original/file-20190730-186809-4g43jx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=698&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/286269/original/file-20190730-186809-4g43jx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=698&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Figures illustrating articles on astronomy, from the 1728 Cyclopaedia.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:Table_of_Astronomy,_Cyclopaedia,_Volume_1,_p_164.jpg">Wikimedia Commons</a></span>
</figcaption>
</figure>
<p>And so, where Galileo had once spurned the idea of a dead world, the German astronomer Wilhelm Olbers <a href="https://journals.sagepub.com/doi/abs/10.1177/002182861304400205">proposed</a> in 1802 that the Mars-Jupiter asteroid belt in fact constitutes the ruins of a shattered planet. Troubled by this, Godwin noted that this would mean that the creator had allowed part of “his creation” to become irremediably “unoccupied”. But scientists were <a href="https://www.biodiversitylibrary.org/item/29601#page/234/mode/1up">soon</a> computing the precise explosive force needed to crack a planet – assigning cold numbers where moral intuitions once prevailed. Olbers <a href="https://zs.thulb.uni-jena.de/receive/jportal_jparticle_00319471">calculated</a> a precise timeframe within which to expect such an event befalling Earth. Poets began writing of “<a href="https://books.google.it/books?id=pdcvAQAAMAAJ&pg=PA137&dq=thomas+beddoes+%22bursten+worlds%22&hl=en&sa=X&ved=0ahUKEwjz2M_4x9jjAhWDDewKHZfTCRYQ6AEIKjAA#v=onepage&q=thomas%20beddoes%20%22bursten%20worlds%22&f=false">bursten worlds</a>”.</p>
<p>The cosmic fragility of life was becoming undeniable. If Earth happened to drift away from the sun, one 1780s Parisian diarist <a href="https://books.google.co.uk/books?id=48APAAAAQAAJ&pg=PA24&dq=mercier+rambling+in+void+space&hl=en&sa=X&ved=0ahUKEwizvoS0-77jAhUdQEEAHU1XBtcQ6AEILDAA#v=onepage&q=mercier%20rambling%20in%20void%20space&f=false">imagined</a> that interstellar coldness would “annihilate the human race, and the earth rambling in the void space, would exhibit a barren, depopulated aspect”. Soon after, the Italian pessimist Giacomo Leopardi <a href="https://books.google.co.uk/books?id=ynNH84gAdNoC&pg=PA419&dq=leopardi+%22frozen+like+pieces+of+rock+crystal%22&hl=en&sa=X&ved=0ahUKEwjC4M7N-77jAhVKi1wKHVe5BWgQ6AEIMzAC#v=onepage&q=leopardi%20%22frozen%20like%20pieces%20of%20rock%20crystal%22&f=false">envisioned</a> the same scenario. He said that, shorn of the sun’s radiance, humanity would “all die in the dark, frozen like pieces of rock crystal”.</p>
<p>Galileo’s inorganic world was now a chilling possibility. Life, finally, had become cosmically delicate. Ironically, this appreciation came not from scouring the skies above but from probing the ground below. Early geologists, during the later 1700s, realised that Earth has its own history and that organic life has not always been part of it. Biology hasn’t even been a permanent fixture down here on Earth – why should it be one elsewhere? Coupled with growing scientific proof that many species had previously become extinct, this slowly transformed our view of the cosmological position of life as the 19th century dawned.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/286266/original/file-20190730-186833-a3v7wl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/286266/original/file-20190730-186833-a3v7wl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=451&fit=crop&dpr=1 600w, https://images.theconversation.com/files/286266/original/file-20190730-186833-a3v7wl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=451&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/286266/original/file-20190730-186833-a3v7wl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=451&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/286266/original/file-20190730-186833-a3v7wl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/286266/original/file-20190730-186833-a3v7wl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/286266/original/file-20190730-186833-a3v7wl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Copper engraving of a pterodactyl fossil discovered by the Italian scientist Cosimo Alessandro Collini in 1784.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:Pterodactylus_holotype_Collini_1784.jpg">Wikimedia Commons</a></span>
</figcaption>
</figure>
<h2>Seeing death in the stars</h2>
<p>And so, where people like Diderot looked up into the cosmos in the 1750s and saw a teeming petri dish of humanoids, writers such as Thomas de Quincey were, by 1854, gazing upon the Orion nebula and <a href="https://books.google.co.uk/books?id=uNtJiUIcN_sC&pg=PA179&dq=de+quincey+%22frightful+depth+to+which+it+is+sunk+in+the+abysses+of+the+heavenly+wilderness%22&hl=en&sa=X&ved=0ahUKEwiZ1NH7-77jAhWKUMAKHRchAk4Q6AEINjAC#v=onepage&q=de%20quincey%20%22frightful%20depth%20to%20which%20it%20is%20sunk%20in%20the%20abysses%20of%20the%20heavenly%20wilderness%22&f=false">reporting</a> that they saw only a gigantic inorganic “skull” and its lightyear-long rictus grin.</p>
<p>The astronomer William Herschel had, already in 1814, <a href="https://books.google.co.uk/books?id=6b80AAAAQBAJ&pg=PA541&dq=herschel+%22kind+of+chronometer%22&hl=en&sa=X&ved=0ahUKEwj33t-V_L7jAhWHX8AKHWesD2IQ6AEIKjAA#v=onepage&q=herschel%20%22kind%20of%20chronometer%22&f=false">realised</a> that looking out into the galaxy one is looking into a “kind of chronometer”. Fermi would spell it out a century after de Quincey, but people were already intuiting the basic notion: looking out into dead space, we may just be looking into our own future.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/284849/original/file-20190718-116547-w9zo7o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/284849/original/file-20190718-116547-w9zo7o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=472&fit=crop&dpr=1 600w, https://images.theconversation.com/files/284849/original/file-20190718-116547-w9zo7o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=472&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/284849/original/file-20190718-116547-w9zo7o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=472&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/284849/original/file-20190718-116547-w9zo7o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=593&fit=crop&dpr=1 754w, https://images.theconversation.com/files/284849/original/file-20190718-116547-w9zo7o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=593&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/284849/original/file-20190718-116547-w9zo7o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=593&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Early drawings of Orion’s nebula by R.S. Newall, 1884.</span>
<span class="attribution"><a class="source" href="https://www.repository.cam.ac.uk/handle/1810/225996?show=full">© Cambridge University</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>People were becoming aware that the appearance of intelligent activity on Earth should not be taken for granted. They began to see that it is something distinct – something that stands out against the silent depths of space. Only through realising that what we consider valuable is not the cosmological baseline did we come to grasp that such values are not necessarily part of the natural world. Realising this was also realising that they are entirely our own responsibility. And this, in turn, summoned us to the modern projects of prediction, preemption and strategising. It is how we came to care about our future.</p>
<p>As soon as people first started discussing human extinction, possible preventative measures were suggested. Bostrom <a href="https://youtu.be/f9HvMLSD0jo">now refers</a> to this as “macrostrategy”. However, as early as the 1720s, the French diplomat Benoît de Maillet was <a href="https://books.google.co.uk/books?id=RO1hAAAAcAAJ&printsec=frontcover#v=onepage&q=%22in%20order%20to%20mainain%22&f=false">suggesting</a> gigantic feats of geoengineering that could be leveraged to buffer against climate collapse. The notion of humanity as a geological force has been around ever since we started thinking about the long-term – it is only recently that scientists have accepted this and given it a name: “Anthropocene”.</p>
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<h2>Will technology save us?</h2>
<p>It wasn’t long before authors began conjuring up highly technologically advanced futures aimed at protecting against existential threat. The eccentric Russian futurologist <a href="https://en.wikipedia.org/wiki/Vladimir_Odoyevsky">Vladimir Odoevskii</a>, writing in the 1830s and 1840s, imagined humanity engineering the global climate and installing gigantic machines to “repulse” comets and other threats, for example. Yet Odoevskii was also keenly aware that with self-responsibility comes risk: the risk of abortive failure. Accordingly, he was also the very first author to propose the possibility that humanity might destroy itself with its own technology.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/betting-on-speculative-geoengineering-may-risk-an-escalating-climate-debt-crisis-119889">Betting on speculative geoengineering may risk an escalating ‘climate debt crisis’</a>
</strong>
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<p>Acknowledgement of this plausibility, however, is not necessarily an invitation to despair. And it remains so. It simply demonstrates appreciation of the fact that, ever since we realised that the universe is not teeming with humans, we have come to appreciate that the fate of humanity lies in our hands. We may yet prove unfit for this task, but – then as now – we cannot rest assured believing that humans, or something like us, will inevitably reappear – here or elsewhere.</p>
<p>Beginning in the late 1700s, appreciation of this has snowballed into our ongoing tendency to be swept up by concern for the deep future. Current initiatives, such as Bostrom’s Future of Humanity Institute, can be seen as emerging from this broad and <a href="https://youtu.be/RiM7IwZWW5g">edifying</a> historical sweep. From ongoing demands for climate justice to dreams of space colonisation, all are continuations and offshoots of a tenacious task that we first began to set for ourselves two centuries ago during the Enlightenment when we first realised that, in an otherwise silent universe, we are responsible for the entire fate of human value.</p>
<p>It may be solemn, but becoming concerned for humanity’s extinction is nothing other than realising one’s obligation to strive for unceasing self-betterment. Indeed, ever since the Enlightenment, we have progressively realised that we must think and act ever better because, should we not, we may never think or act again. And that seems – to me at least – like a very rational end of the world.</p>
<hr>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=112&fit=crop&dpr=1 600w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=112&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=112&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=140&fit=crop&dpr=1 754w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=140&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=140&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
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<p><em>For you: more from our <a href="https://theconversation.com/uk/topics/insights-series-71218?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=InsightsUK">Insights series</a>:</em></p>
<ul>
<li><p><em><a href="https://theconversation.com/environmental-stress-is-already-causing-death-this-chaos-map-shows-where-123796?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=InsightsUK">‘Environmental stress is already causing death – this chaos map shows where
</a></em></p></li>
<li><p><em><a href="https://theconversation.com/futurology-how-a-group-of-visionaries-looked-beyond-the-possible-a-century-ago-and-predicted-todays-world-118134?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=InsightsUK">Futurology: how a group of visionaries looked beyond the possible a century ago and predicted today’s world</a></em></p></li>
<li><p><em><a href="https://theconversation.com/charles-dickens-newly-discovered-documents-reveal-truth-about-his-death-and-burial-13007?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=InsightsUK9">Charles Dickens: newly discovered documents reveal truth about his death and burial</a></em></p></li>
</ul>
<p><em>To hear about new Insights articles, join the hundreds of thousands of people who value The Conversation’s evidence-based news. <a href="https://theconversation.com/uk/newsletters/the-daily-newsletter-2?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=InsightsUK"><strong>Subscribe to our newsletter</strong></a>.</em></p><img src="https://counter.theconversation.com/content/120193/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Thomas Moynihan received funding from the Arts and Humanities Research Council (2014-2017).</span></em></p>
Realising the silence of outer space was what made us appreciate our precarious position down on this pale blue dot – so beginning our obsession with extinction.
Thomas Moynihan, PhD Candidate, University of Oxford
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/98843
2018-06-28T11:02:02Z
2018-06-28T11:02:02Z
Are we alone? The question is worthy of serious scientific study
<figure><img src="https://images.theconversation.com/files/224792/original/file-20180625-19411-1bdn3yc.png?ixlib=rb-1.1.0&rect=5%2C11%2C1264%2C1279&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">US F/A-18 footage of a UFO (circled in red).
Creative Commons Attribution-Share Alike 4.0 International license. </span> <span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Unidentified_flying_object#/media/File:UFO_Image,_2.png">Parzival191919</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span></figcaption></figure><p>Are we alone? Unfortunately, neither of the answers feel satisfactory. To be alone in this vast universe is a lonely prospect. On the other hand, if we are not alone and there is someone or something more powerful out there, that too is terrifying. </p>
<p>As a NASA research scientist and now a professor of physics, I attended the <a href="http://www.cuebon.com/contact/index.html">2002 NASA Contact Conference</a>, which focused on serious speculation about extraterrestrials. During the meeting a concerned participant said loudly in a sinister tone, “You have absolutely no idea what is out there!” The silence was palpable as the truth of this statement sunk in. Humans are fearful of <a href="http://www.survivingdeathkean.com/ufos/">extraterrestrials visiting Earth</a>. Perhaps fortunately, the distances between the stars are prohibitively vast. At least this is what we novices, who are just learning to travel into space, tell ourselves. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/224791/original/file-20180625-19385-xw1t5p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/224791/original/file-20180625-19385-xw1t5p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/224791/original/file-20180625-19385-xw1t5p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=829&fit=crop&dpr=1 600w, https://images.theconversation.com/files/224791/original/file-20180625-19385-xw1t5p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=829&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/224791/original/file-20180625-19385-xw1t5p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=829&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/224791/original/file-20180625-19385-xw1t5p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1042&fit=crop&dpr=1 754w, https://images.theconversation.com/files/224791/original/file-20180625-19385-xw1t5p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1042&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/224791/original/file-20180625-19385-xw1t5p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1042&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Cover of the October 1957 issue of pulp science fiction magazine Amazing Stories. This was a special edition devoted to ‘flying saucers,’ which became a national obsession after airline pilot Kenneth Arnold sighted a saucer-shaped flying objects in 1947.</span>
</figcaption>
</figure>
<p>I have always been interested in UFOs. Of course, there was the excitement that there could be aliens and other living worlds. But more exciting to me was the possibility that interstellar travel was technologically achievable. In 1988, during my second week of graduate school at Montana State University, several students and I were discussing a recent cattle mutilation that was associated with UFOs. A physics professor joined the conversation and told us that he had colleagues working at Malmstrom Air Force Base in Great Falls, Montana, where they were having problems with UFOs shutting down nuclear missiles. At the time I thought this professor was talking nonsense. But 20 years later, I was stunned to see <a href="https://www.youtube.com/watch?v=3jUU4Z8QdHI">a recording of a press conference</a> featuring several former US Air Force personnel, with a couple from Malmstrom AFB, describing similar occurrences in the 1960s. Clearly there must be something to this.</p>
<p>With July 2 being World UFO Day, it is a good time for society to address the unsettling and refreshing fact we may not be alone. I believe we need to face the possibility that some of the strange flying objects that outperform the best aircraft in our inventory and defy explanation may indeed be visitors from afar – and there’s plenty of evidence to support UFO sightings. </p>
<h2>The Fermi paradox</h2>
<p>The nuclear physicist Enrico Fermi was famous for posing thought provoking questions. In 1950, at Los Alamos National Laboratory after discussing UFOs over lunch, <a href="https://www.osti.gov/accomplishments/documents/fullText/ACC0055.pdf">Fermi asked</a>, “Where is everybody?” He estimated there were about 300 billion stars in the galaxy, many of them billions of years older than the sun, with a large percentage of them likely to host habitable planets. Even if intelligent life developed on a very small percentage of these planets, then there should be a number of intelligent civilizations in the galaxy. Depending on the assumptions, one should expect anywhere from <a href="https://arxiv.org/pdf/0810.2222.pdf">tens to tens of thousands of civilizations</a>.</p>
<p>With the rocket-based technologies that we have developed for space travel, it would take between 5 and 50 million years for a civilization like ours to colonize our Milky Way galaxy. Since this should have happened several times already in the history of our galaxy, one should wonder where is the evidence of these civilizations? This discrepancy between the expectation that there should be evidence of alien civilizations or visitations and the presumption that no visitations have been observed has been dubbed the Fermi Paradox.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/224951/original/file-20180626-112601-1fj1xsk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/224951/original/file-20180626-112601-1fj1xsk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/224951/original/file-20180626-112601-1fj1xsk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=459&fit=crop&dpr=1 600w, https://images.theconversation.com/files/224951/original/file-20180626-112601-1fj1xsk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=459&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/224951/original/file-20180626-112601-1fj1xsk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=459&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/224951/original/file-20180626-112601-1fj1xsk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=577&fit=crop&dpr=1 754w, https://images.theconversation.com/files/224951/original/file-20180626-112601-1fj1xsk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=577&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/224951/original/file-20180626-112601-1fj1xsk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=577&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This photograph was taken in Wallonia, Belgium.</span>
<span class="attribution"><span class="source">J.S. Henrardi</span></span>
</figcaption>
</figure>
<p>Carl Sagan correctly summarized the situation by saying that “extraordinary claims require extraordinary evidence.” The problem is that there has been no single well-documented UFO encounter that would alone qualify as the smoking gun. The situation is exacerbated by the fact that many governments around the world have <a href="https://www.bbc.com/news/uk-10853905">covered up</a> <a href="http://www.survivingdeathkean.com/ufos/">and classified</a> <a href="https://www.nytimes.com/2016/05/11/us/politics/hillary-clinton-aliens.html">information about</a> <a href="https://www.huffingtonpost.com/entry/john-podesta-hillary-clinton-ufos_us_56d730c9e4b03260bf78f129">such encounters</a>. But there are enough scraps of evidence that suggest that the problem needs to be open to scientific study.</p>
<h2>UFOs, taboo for professional scientists</h2>
<p>When it comes to science, the scientific method requires hypotheses to be testable so that inferences can be verified. UFO encounters are neither controllable nor repeatable, which makes their study extremely challenging. But the real problem, in my view, is that the UFO topic is taboo. </p>
<p>While the general public has been fascinated with UFOs for decades, our governments, scientists and media, have essentially declared that of all the UFO sightings are a result of weather phenomenon or human actions. None are actually extraterrestrial spacecraft. And no aliens have visited Earth. Essentially, we are told that the topic is nonsense. UFOs are off-limits to serious scientific study and rational discussion, which unfortunately leaves the topic in the domain of fringe and pseudoscientists, many of whom litter the field with conspiracy theories and wild speculation. </p>
<p>I think UFO skepticism has become something of a religion with an agenda, discounting the possibility of extraterrestrials without scientific evidence, while often providing silly hypotheses describing only one or two aspects of a UFO encounter reinforcing the popular belief that there is a conspiracy. A scientist must consider all of the possible hypotheses that explain all of the data, and since little is known, the extraterrestrial hypothesis cannot yet be ruled out. In the end, the skeptics often do science a disservice by providing a poor example of how science is to be conducted. The fact is that many of these encounters – still a very small percentage of the total – defy conventional explanation. </p>
<p>The media amplifies the skepticism by publishing information about UFOs when it is exciting, but always with a mocking or whimsical tone and reassuring the public that it can’t possibly be true. But there are credible witnesses and encounters. </p>
<h2>Why don’t astronomers see UFOs?</h2>
<p>I am often asked by friends and colleagues, “Why don’t astronomers see UFOs?” The fact is that they do. In 1977, Peter Sturrock, a professor of space science and astrophysics at Stanford University, mailed 2,611 <a href="http://alien-ufo-sightings.com/wp-content/uploads/2017/04/jse_08_1_sturrock.pdf">questionnaires about UFO sightings</a> to members of the American Astronomical Society. He received 1,356 responses from which 62 astronomers – 4.6 percent – reported witnessing or recording inexplicable aerial phenomena. This rate is similar to the approximately <a href="http://www.nbcnews.com/id/38977500/ns/technology_and_science-space/t/skeptic-misses-point-behind-ufo-book/#.WzFAcKdKhPY">5 percent of UFO sightings that are never explained</a>.</p>
<p>As expected, Sturrock found that astronomers who witnessed UFOs were more likely to be night sky observers. Over 80 percent of Sturrock’s respondents were willing to study the UFO phenomenon if there was a way to do so. More than half of them felt that the topic deserves to be studied versus 20 percent who felt that it should not. The survey also revealed that younger scientists were more likely to support the study of UFOs. </p>
<p>UFOs have been observed through telescopes. I know of one telescope sighting by an experienced amateur astronomer in which he observed an object shaped like a guitar pick moving through the telescope’s field of view. Further sightings are documented in the book “<a href="http://www.jacquesvallee.net/wonders_in_the_sky.html">Wonders in the Sky</a>,” in which the authors compile numerous observations of unexplained aerial phenomena made by astronomers and published in scientific journals throughout the 1700s and 1800s. </p>
<h2>Evidence from government and military officers</h2>
<p>Some of the most convincing observations have come from government officials. In 1997, the Chilean government formed the organization Comité de Estudios de Fenómenos Aéreos Anómalos, or CEFAA, to study UFOs. Last year, <a href="http://www.newsweek.com/chilean-navy-id-mysterious-aircraft-caught-video-539786">CEFAA released footage</a> of a UFO taken with a helicopter-mounted Wescam infrared camera. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/224797/original/file-20180625-19421-1l5fb8j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/224797/original/file-20180625-19421-1l5fb8j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/224797/original/file-20180625-19421-1l5fb8j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=427&fit=crop&dpr=1 600w, https://images.theconversation.com/files/224797/original/file-20180625-19421-1l5fb8j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=427&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/224797/original/file-20180625-19421-1l5fb8j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=427&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/224797/original/file-20180625-19421-1l5fb8j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=536&fit=crop&dpr=1 754w, https://images.theconversation.com/files/224797/original/file-20180625-19421-1l5fb8j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=536&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/224797/original/file-20180625-19421-1l5fb8j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=536&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Declassified document describing a sighting of a UFO in December 1977, in Bahia, a state in northern Brazil.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Registro_de_avistamento_de_Objeto_Voador_N%C3%A3o_Identificado_-_OVNI_ocorrido_em_dezembro_de_1977,_na_Bahia.jpg">Arquivo Nacional Collection</a></span>
</figcaption>
</figure>
<p>The countries of <a href="https://www.bbc.com/news/world-latin-america-10947856">Brazil</a>, Canada, Denmark, Ecuador, France, New Zealand, Russia, Sweden and the United Kingdom have been declassifying their UFO files since 2008. The French Committee for In-Depth Studies, or COMETA, was an unofficial UFO study group comprised of high-ranking scientists and military officials that studied UFOs in the late 1990s. They released the <a href="https://archive.org/details/TheCometaReport">COMETA Report</a>, which summarized their findings. They concluded that 5 percent of the encounters were reliable yet inexplicable: The best hypothesis available was that the observed craft were extraterrestrial. They also accused the United States of covering up evidence of UFOs. <a href="https://www.forbes.com/sites/michaelpeck/2014/01/14/did-iranian-fighters-battle-ufos/#5c70bb551a32">Iran has been concerned about spherical UFOs</a> observed near nuclear power facilities that they call “CIA drones” which reportedly are about 30 feet in diameter, can achieve speeds up to Mach 10, and can leave the atmosphere. Such speeds are on par with the fastest experimental aircraft, but unthinkable for a sphere without lift surfaces or an obvious propulsion mechanism. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/224798/original/file-20180625-19382-1nvhk7d.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/224798/original/file-20180625-19382-1nvhk7d.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/224798/original/file-20180625-19382-1nvhk7d.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=843&fit=crop&dpr=1 600w, https://images.theconversation.com/files/224798/original/file-20180625-19382-1nvhk7d.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=843&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/224798/original/file-20180625-19382-1nvhk7d.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=843&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/224798/original/file-20180625-19382-1nvhk7d.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1059&fit=crop&dpr=1 754w, https://images.theconversation.com/files/224798/original/file-20180625-19382-1nvhk7d.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1059&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/224798/original/file-20180625-19382-1nvhk7d.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1059&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">1948 Top Secret USAF UFO extraterrestrial document.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:1948_Top_Secret_USAF_UFO_extraterrestrial_document.png">United States Air Force</a></span>
</figcaption>
</figure>
<p>In December 2017, The New York Times broke a story about the classified Advanced Aviation Threat Identification Program, which was a $22 million program run by the <a href="https://www.nytimes.com/2017/12/16/us/politics/unidentified-flying-object-navy.html">former Pentagon official Luis Elizondo</a> and aimed at studying UFOs. Elizondo resigned from running the program protesting <a href="https://www.nytimes.com/2017/12/18/insider/secret-pentagon-ufo-program.html">extreme secrecy</a> and the <a href="https://www.washingtonpost.com/outlook/the-military-keeps-encountering-ufos-why-doesnt-the-pentagon-care/2018/03/09/242c125c-22ee-11e8-94da-ebf9d112159c_story.html?noredirect=on&utm_term=.83d7aa0c9980">lack of funding and support</a>. Following his resignation Elizondo, along with several others from the defense and intelligence community, were recruited by the <a href="https://coi.tothestarsacademy.com">To the Stars Academy of Arts & Science</a>, which was recently founded by <a href="https://www.rollingstone.com/music/news/tom-delonge-announces-to-the-stars-academy-of-arts-science-w508312">Tom DeLonge</a> to study UFOs and interstellar travel. In conjunction with the launch of the academy, the Pentagon declassified and released three videos of UFO encounters taken with forward looking infrared cameras mounted on F-18 fighter jets. While there is much excitement about such disclosures, I am reminded of a <a href="https://lasvegasweekly.com/blogs/luxe-life/2011/feb/25/evidence-overwhelming-ufos-are-real-retired-army-c/">quote from Retired Army Colonel John Alexander</a>: “Disclosure has happened. … I’ve got stacks of generals, including Soviet generals, who’ve come out and said UFOs are real. My point is, how many times do senior officials need to come forward and say that this is real?”</p>
<h2>A topic worthy of serious study</h2>
<p>There is a great deal of evidence that a small percentage of these UFO sightings are unidentified structured craft exhibiting flight capabilities beyond any known human technology. While there is no single case for which there exists evidence that would stand up to scientific rigor, there are cases with simultaneous observations by multiple reliable witnesses, along with radar returns and photographic evidence revealing patterns of activity that are compelling. </p>
<p>Declassified information from covert studies is interesting, but not scientifically helpful. This is a topic worthy of open scientific inquiry, until there is a scientific consensus based on evidence rather than prior expectation or belief. If there are indeed extraterrestrial craft visiting Earth, it would greatly benefit us to know about them, their nature and their intent. Moreover, this would present a great opportunity for mankind, promising to expand and advance our knowledge and technology, as well as reshaping our understanding of our place in the universe.</p><img src="https://counter.theconversation.com/content/98843/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kevin Knuth does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
About 5 percent of all UFO sightings cannot be easily explained by weather or human technology. A physicist argues that there’s compelling evidence to justify serious scientific study and that the skeptics should step aside – for the sake of humanity.
Kevin Knuth, Associate Professor of Physics, University at Albany, State University of New York
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/96694
2018-06-12T19:59:58Z
2018-06-12T19:59:58Z
In physics, a famous paradox that hangs by a thread of light…
<figure><img src="https://images.theconversation.com/files/219379/original/file-20180517-155573-15imsa5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">file pwxht</span> </figcaption></figure><p>Imagine a metal bar that has been heated at one end. Instead of the heat gradually spreading over its entire length, the bar eventually becomes hot again at the place where it was originally. The fact that, paradoxically, a complex system returns to its original state instead of evolving toward equilibrium has drawn the attention of physicists for more than 60 years. Thanks to a series of advances in optical fibres, much richer and complete than before, our French-Italian team of researchers has just taken a crucial step in better understanding this phenomenon.</p>
<p><a href="https://www.researchgate.net/publication/324162686_Fibre_multi-wave_mixing_combs_reveal_the_broken_symmetry_of_Fermi-Pasta-Ulam_recurrence">Our publication</a>, which describes his progress, was featured on the cover of <em>Nature Photonics</em>. These are not only top results in fundamental physics but also of primary interest for the general public – the process in question is at the heart of phenomena such as the formation of rogue ocean waves or the design of high-precision optical clocks.</p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/217226/original/file-20180502-153891-xotn7t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/217226/original/file-20180502-153891-xotn7t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=744&fit=crop&dpr=1 600w, https://images.theconversation.com/files/217226/original/file-20180502-153891-xotn7t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=744&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/217226/original/file-20180502-153891-xotn7t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=744&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/217226/original/file-20180502-153891-xotn7t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=934&fit=crop&dpr=1 754w, https://images.theconversation.com/files/217226/original/file-20180502-153891-xotn7t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=934&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/217226/original/file-20180502-153891-xotn7t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=934&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Enrico Fermi.</span>
<span class="attribution"><a class="source" href="https://fr.wikipedia.org/wiki/Enrico_Fermi#/media/File:Enrico_Fermi_1943-49.jpg">Department of Energy/Wikipedia</a></span>
</figcaption>
</figure>
<h2>The Manhattan project at the origin of the paradox</h2>
<p>The paradox was first discovered in 1954 by leading scientists, some of whom were involved in the <a href="https://www.britannica.com/event/Manhattan-Project">Manhattan Project</a>, which would provide the United States with the atomic bomb. They were <a href="https://en.wikipedia.org/wiki/Stanislaw_Ulam">Stanislaw Ulam</a>, <a href="https://en.wikipedia.org/wiki/John_Pasta">John Pasta</a>, and <a href="https://en.wikipedia.org/wiki/Mary_Tsingou">Mary Tsingou</a>, and <a href="https://en.wikipedia.org/wiki/Enrico_Fermi">Enrico Fermi</a>, winner of the 1938 Nobel Prize in physics. Fermi has the idea of using one of the first-ever computers to explore new complex physical phenomena whose resolution was not possible by calculation. This marks the beginning of a revolution – numerical simulations – that has become essential in all areas of physics.</p>
<p>But for Fermi and his colleagues, the results of the first computer test revealed some completely unexpected behaviour: The system they were studying returned to its initial state.</p>
<p>Since then, the problem has been studied and written about extensively. The repeated efforts of physicists to solve it have been particularly fruitful for many branches of physics where it can be observed. In particular, they led to the discovery of the theory of <a href="https://en.wikipedia.org/wiki/Soliton">solitons</a>, pulses that propagate without deformation that can be observed in oceans, plasma physics and optics.</p>
<p>Some models predicted that the Fermi, Pasta and Ulam phenomenon was actually cyclical – the system returning several times to its initial state. But the experiments that had highlighted it had never detected anything more than a return to the original state: intrinsic losses of the system mitigated its manifestations too quickly.</p>
<h2>Optical fibres observe the paradox</h2>
<p>Our research team, based at the University of Lille’s <a href="http://www.phlam.univ-lille1.fr/">PHLAM Laboratory</a> and associated with an Italian theorist from the University of Ferrara, has managed to find a way to compensate these losses over more than 8 kilometres of optical fibre by adding a light source of a very different colour that served as an energy reservoir. This unprecedented process allowed us to observe for the first time a second return to the initial state. The experiment took place at the <a href="http://fibertech.univ-lille.fr/presentation">FiberTech Lille</a> facility, part of the <a href="http://www.ircica.univ-lille1.fr/">IRCICA</a> research institution.</p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/217185/original/file-20180502-153914-1q248c6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/217185/original/file-20180502-153914-1q248c6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/217185/original/file-20180502-153914-1q248c6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/217185/original/file-20180502-153914-1q248c6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/217185/original/file-20180502-153914-1q248c6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/217185/original/file-20180502-153914-1q248c6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/217185/original/file-20180502-153914-1q248c6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Light scattering in an optical fibre.</span>
</figcaption>
</figure>
<p>Thanks to an ingenious device that looked at diffusion of light by impurities within the fibre, known as <a href="http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/blusky.html">Rayleigh scattering</a>, we were able to measure not only the intensity of the light but also what the optical specialists call its phase, and this along the whole fibre length. We then observed an unprecedented behaviour: recurrent shifts from one cycle to another, the maxima taking the place of the minima.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/217259/original/file-20180502-153888-lgno7r.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/217259/original/file-20180502-153888-lgno7r.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=607&fit=crop&dpr=1 600w, https://images.theconversation.com/files/217259/original/file-20180502-153888-lgno7r.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=607&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/217259/original/file-20180502-153888-lgno7r.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=607&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/217259/original/file-20180502-153888-lgno7r.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=762&fit=crop&dpr=1 754w, https://images.theconversation.com/files/217259/original/file-20180502-153888-lgno7r.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=762&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/217259/original/file-20180502-153888-lgno7r.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=762&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Several Fermi-Pasta-Ulam recurrences, with alternating maxima (red) and minima (light blue).</span>
</figcaption>
</figure>
<p>This result, predicted by some models, opens a new way in the understanding of this phenomenon, which at the root of many other complex processes: <a href="https://en.wikipedia.org/wiki/Frequency_comb">frequency combs</a>. These “laser rules”, advancing swiftly in recent years, bring light into a large number of new applications, ranging from distance measurement for autonomous cars to the discovery of exoplanets, to name just a few.</p><img src="https://counter.theconversation.com/content/96694/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Arnaud Mussot has received funding from the Agence Nationale de la Recherche (ANR), the Labex Centre Europeen pour les Mathematiques, la Physique et leurs Interactions (CEMPI), the FLUX team and the Hauts-de-France region. He is a member of the Institut Universitaire de France.</span></em></p><p class="fine-print"><em><span>Matteo Conforti has received funding from Agence Nationale de la Recherche (ANR) under projects NoAWE and CEMPI, and the Hauts-de-France region.
</span></em></p><p class="fine-print"><em><span>Stefano Trillo receives funding from Italian Ministry of University and Research (MIUR) under PRIN action, and from University of Ferrara under FAR action.</span></em></p>
In 1954, three scientists observed a paradox to which they gave their name: the Fermi-Pasta-Ulam recurrence. Now, fibre optics are on the way to finally providing an explanation.
Arnaud Mussot, Professeur au Laboratoire de Physique des Lasers Atomes et Molécules (PHLAM), CNRS UMR8523, IRCICA, Université de Lille
Matteo Conforti, Chercheur au Laboratoire de Physique des Lasers, Atomes et Molécules, Université de Lille
Stefano Trillo, Professor of Optics, University of Ferrara
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/72804
2017-02-15T18:07:09Z
2017-02-15T18:07:09Z
Newly discovered Churchill essay on aliens is a timely reminder of the dangers facing life on Earth
<figure><img src="https://images.theconversation.com/files/156908/original/image-20170215-19598-1dhglu2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/dmstrom/8059826237/">Dave Strom/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>Buried within the archives of a museum in Missouri, an essay on the search for alien life has come to light, 78 years after it was penned. Written on the brink of the second world war, its unlikely author is the political leader Winston Churchill. </p>
<p>If the British prime minister was seeking solace in the prospect of life beyond our war-torn planet, would the discovery of a plethora of exoplanets aid or hinder such comfort?</p>
<p>The 11-page article – Are We Alone in the Universe? – has sat in the US National Churchill Museum archives in Fulton, Missouri from the 1980s until it was <a href="http://nature.com/articles/doi:10.1038/542289a">reviewed by astrophysicist Mario Livio</a> in this week’s edition of the journal Nature. </p>
<p>Livio highlights that the unpublished text shows Churchill’s arguments were extremely contemporary for a piece written nearly eight decades previously. In it, Churchill speculates on the conditions needed to support life but notes the difficulty in finding evidence due to the vast distances between the stars.</p>
<p>Churchill fought the darkness of wartime with his trademark inspirational speeches and <a href="http://www.bbc.com/news/science-environment-30915445">championing of science</a>. This latter passion led to the <a href="http://www.telegraph.co.uk/news/science/science-news/11260316/How-Churchill-gave-us-tanks-radar-DNA...and-a-velvet-green-air-raid-suit.html">development of radar</a>, which proved instrumental to victory over Nazi Germany, and a boom in scientific advancement in post-war Britain.</p>
<p>Churchill’s writings on science reveal him to be a visionary. Publishing a piece entitled <a href="http://rolandanderson.se/Winston_Churchill/Fifty_Years_Hence.php">Fifty Years Hence</a> in 1931, he detailed future technologies from the atomic bomb and wireless communications to genetic engineered food and even humans. But as his country faced the uncertainty of another world war, Churchill’s thoughts turned to the possibility of life on other worlds.</p>
<h2>In the shadow of war</h2>
<p>Churchill was not alone in contemplating alien life as war ripped across the globe. </p>
<p>Just before he wrote his first draft in 1939, <a href="http://www.smithsonianmag.com/history/infamous-war-worlds-radio-broadcast-was-magnificent-fluke-180955180/">a radio adaption of HG Wells’ 1898 novel War of the Worlds was broadcast</a> in the US. Newspapers reported nationwide panic at the realistic depiction of a Martian invasion, although in truth <a href="http://www.telegraph.co.uk/radio/what-to-listen-to/the-war-of-the-worlds-panic-was-a-myth/">the number of people fooled was probably far smaller</a>. </p>
<p>The <a href="http://www.bbc.com/news/uk-10853905">British government was also taking the prospect</a> of extraterrestrial encounters seriously, receiving weekly ministerial briefings on UFO sightings in the years following the war. Concern that mass hysteria would result from any hint of alien contact resulted in Churchill forbidding an unexplained wartime encounter with an RAF bomber from being reported.</p>
<p>Faced with the prospect of widespread destruction during a global war, the raised interest in life beyond Earth could be interpreted as being driven by hope. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/156906/original/image-20170215-20678-1646kch.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/156906/original/image-20170215-20678-1646kch.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/156906/original/image-20170215-20678-1646kch.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/156906/original/image-20170215-20678-1646kch.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/156906/original/image-20170215-20678-1646kch.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/156906/original/image-20170215-20678-1646kch.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/156906/original/image-20170215-20678-1646kch.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The British government took the prospect of extraterrestrial encounters seriously.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/andrepax/24017367136/">Andrea Passoni/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Discovery of an advanced civilisation might imply the huge ideological differences revealed in wartime could be surmounted. If life was common, could we one day spread through the Galaxy rather than fight for a single planet? Perhaps if nothing else, an abundance of life would mean nothing we did on Earth would affect the path of creation. </p>
<p>Churchill himself appeared to subscribe to the last of these, writing:</p>
<blockquote>
<p>I, for one, am not so immensely impressed by the success we are making of our civilisation here that I am prepared to think we are the only spot in this immense universe which contains living, thinking creatures.</p>
</blockquote>
<h2>A profusion of new worlds</h2>
<p>Were Churchill prime minister now, he might find himself facing a similar era of political and economic uncertainty. Yet in the 78 years since he first penned his essay, we have gone from knowing of no planets outside our Solar System to the <a href="http://exoplanetarchive.ipac.caltech.edu/">discovery of around 3,500 worlds orbiting around other stars</a>. </p>
<p>Had Churchill lifted his pen now – or rather, touched his stylus to his iPad Pro – he would have known planets could form around nearly every star in the sky.</p>
<p>This profusion of new worlds might have heartened Churchill and many parts of his essay remain relevant to modern planetary science. He noted the importance of water as a medium for developing life and that the Earth’s distance from the Sun allowed a surface temperature capable of maintaining water as a liquid. </p>
<p>He even appears to have touched on the fact that a planet’s gravity would determine its atmosphere, <a href="https://theconversation.com/until-we-get-better-tools-excited-reports-of-habitable-planets-need-to-come-back-down-to-earth-72425">a point frequently missed</a> when considering how Earth-like a new planet discovery may be.</p>
<p>To this, a modern-day Churchill could have added the importance of identifying biosignatures; observable changes in a planet’s atmosphere or reflected light that may indicate the influence of a biological organism. The <a href="https://jwst.nasa.gov/origins.html">next generation of telescopes</a> aim to collect data for such a detection. </p>
<p>By observing starlight passing through a planet’s atmosphere, the composition of gases can be determined from a fingerprint of missing wavelengths that have been absorbed by the different molecules. Direct imaging of a planet may also reveal seasonal shifts in the reflected light as plant life blooms and dies on the surface. </p>
<h2>Where is everybody?</h2>
<p>But Churchill’s thoughts may have taken a darker turn in wondering why there was no sign of intelligent life in a Universe packed with planets. The question “Where is everybody?” was posed in a casual lunchtime conversation by Enrico Fermi and went on to become known as the <a href="http://www.seti.org/seti-institute/project/details/fermi-paradox">Fermi Paradox</a>. </p>
<p>The solutions proposed take the form of a great filter or bottleneck that life finds very difficult to struggle past. The question then becomes whether the filter is behind us and we have already survived it, or if it lies ahead to stop us spreading beyond planet Earth.</p>
<p>Filters in our past could include a so-called “emergence bottleneck” that proposes that life is very difficult to kick-start. Many organic molecules such as amino acids and nucleobases seem amply able to form and be delivered to terrestrial planets within meteorites. But the progression from this to more complex molecules may require very exact conditions that are rare in the Universe. </p>
<p>The continuing interest in finding evidence for life on Mars is linked to this quandary. Should we find a separate genesis of life in the Solar System – even one that fizzled out – it would suggest the emergence bottleneck didn’t exist.</p>
<p>It could also be that life is needed to maintain habitable conditions on a planet. The “Gaian bottleneck” proposes that life needs to evolve rapidly enough to regulate the planet’s atmosphere and stabilise conditions needed for liquid water. Life that develops too slowly <a href="http://online.liebertpub.com/doi/10.1089/ast.2015.1387">will end up going extinct</a> on a dying world. </p>
<p>A third option is that life develops relatively easily, but evolution rarely results in the rationality required for human-level intelligence. </p>
<p>The existence of any of those early filters is at least not evidence that the human race cannot prosper. But it could be that the filter for an advanced civilisation lies ahead of us. </p>
<p>In this bleak picture, many planets have developed intelligent life that inevitably annihilates itself before gaining the ability to spread between star systems. Should Churchill have considered this on the eve of the second world war, he may well have considered it a probable explanation for the Fermi Paradox.</p>
<p>Churchill’s name went down in history as the iconic leader who took Britain successfully through the second world war. At the heart of his policies was an environment that allowed science to flourish. Without a similar attitude in today’s politics, we may find we hit a bottleneck for life that leaves a Universe without a single human soul to enjoy it.</p><img src="https://counter.theconversation.com/content/72804/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Elizabeth Tasker does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Churchill allowed science to flourish. Without a similar attitude in today’s politics, we may hit a bottleneck for life that leaves a Universe without a single human soul to enjoy it.
Elizabeth Tasker, Associate Professor, Japan Aerospace Exploration Agency (JAXA)
Licensed as Creative Commons – attribution, no derivatives.