Hope Notes: Detecting  Aliens in our Lifetime

By Scot Noel

When I fell in love with Star Trek on the evening of September 8th, 1966 (yes, it was love at first sight), there were no planets outside of our solar system.

Allow me to clarify. While at the time there was a strong sense that many stars must have planetary systems, direct proof of this would not happen for almost 3 decades more, when, in 1992, astronomers Aleksander Wolszczan and Dale Frail discovered two planets orbiting a pulsar (PSR B1257+12).

As of August 21, 2024, NASA has confirmed 5,747 exoplanets in 4,289 planetary systems.

Since the Milky Way contains an estimated 100-400 billion stars, with most stars likely hosting planets, our Milky Way galaxy alone may host hundreds of billions to over a trillion exoplanets.

5% of those might be Earth-like worlds in their star’s habitable zone. You do the math. It’s a very big number. Billions and billions of Earths, relatively close to home.

Now, the title of this article is “detecting,” not visiting or communicating with. Humans are rapidly developing the gear necessary to simply look out across the stars and see what we’re looking for.

Earth-like Atmospheres and Signs of Industrial Pollution

Detecting industrial pollution in Earth-like atmospheres represents one of the most intriguing possibilities in the search for ET. Industrial pollutants, such as chlorofluorocarbons (CFCs) and other synthetic compounds, do not occur naturally in significant quantities and could serve as clear indicators of technological activity.

By analyzing the atmospheres of exoplanets for these compounds, scientists can infer the presence of manufacturing processes akin to those found on Earth.

With its advanced spectrographic capabilities, the James Webb Space Telescope (JWST) can analyze the chemical composition of exoplanetary atmospheres.  JWST can detect specific absorption lines that indicate the presence of various molecules, including potential industrial pollutants.

City Lights on the Dark Side

Detecting city lights on the dark sides of planets would be a direct indicator of advanced civilization. Observing such large-scale artificial illumination would mean being able to distinguish city lights from natural sources such as volcanic activity or lightning.

Artificial lights would show distinct spectral characteristics, with certain wavelengths more prominent than those typically produced by natural processes. The regular patterns and intensities of city lights, potentially following a grid-like structure, would further mark them as technical in nature

The equipment required to detect such faint and distant sources of light is rapidly advancing. The James Webb Space Telescope (JWST) and the Nancy Grace Roman Space Telescope are particularly promising for this type of observation.  JWST has already had one false alarm in this regard earlier this year.

Detecting these lights would not only confirm the existence of alien civilizations but also provide insights into their technological state and energy usage.

Detecting Dyson Swarms

Dyson Swarms are named after a proposal made by the physicist Freeman Dyson. They represent an advanced stage of civilization where a multitude of satellites, solar collectors, or even habitats orbit a star, capturing its energy output. These structures would greatly extend a civilization's energy resources, providing power far beyond what a single planet could offer, no matter its natural resources.

Detecting a Dyson Swarm involves identifying unusual patterns in a star's light. Any structure like a Dyson Swarm (or a more advanced Dyson Sphere) would cause periodic and irregular dimming of the home star.

The Kepler Space Telescope and its successor, the Transiting Exoplanet Survey Satellite (TESS), have already proven their ability to detect exoplanets by observing the dips in starlight caused by planetary transits. These same methods can be adapted to search for the dimming patterns of a Dyson Swarm.

Future telescopes, like the European Extremely Large Telescope (E-ELT) and the proposed LUVOIR (Large UV/Optical/IR Surveyor), will have even greater sensitivity and resolution, allowing for more detailed studies, one of which may detect a Dyson Swarm, even if that’s not what they’re looking for!

Recently, astronomers found 60 Dyson swarm candidates, among millions of searched stars. (Likely they are not truly alien megastructures, but figuring out what they are will undoubtedly advance our knowledge of the possible.)

Other Detection Possibilities

Beyond what are quickly becoming “conventional methods” of detecting alien civilizations, several other possibilities come to mind.

Asteroid mining. Spacefaring civilizations will need resources outside of their native gravity well. Asteroids are great place to find what they’re looking for. Evidence of mining could include unusual patterns of asteroid motion, missing mass from asteroid belts, or changes in the composition of asteroids. By monitoring these indicators, we might uncover indirect evidence of alien civilizations exploiting their local resources.

Star Lifting. A more advanced version of resource extraction, star lifting is a process of extracting material directly from a star’s surface for energy or resource use. Available are hydrogen and helium, along with metals and metalloids, and even rare elements such as platinum, gold, and other heavy elements, depending on the type and age of the star.

The work involves manipulating a star’s outer layers, resulting in unusual stellar activity or anomalies in a star's composition and light spectrum. Changes in a star's brightness or spectrum that cannot be explained by natural processes might suggest the presence of an advanced civilization engaging in star lifting.

Warp Signatures. If advanced alien civilizations have developed technologies to manipulate spacetime for faster-than-light travel, these activities could leave behind detectable traces. Gravitational wave observatories like LIGO (Laser Interferometer Gravitational-Wave Observatory) and its successors might be able to identify anomalies in spacetime that indicate the presence of warp drives. These signatures would be unlike anything produced by natural astrophysical processes, offering a potential indicator of advanced extraterrestrial technology.

Whatever is Out There, We May See It Soon!

Whatever life is in the universe, we may see it soon, if we’re smart enough to know both what we’re looking for and what we’re looking at.

Our instrumentality has already detected a variety of phenomena, from Fast Radio Bursts to Unexplained X-ray Sources, from Excess Infrared Stellar Emissions to Pulsar Timing Anomalies. And then there was that derelict space craft (I mean that unusually shaped rock) Oumuamua that passed through the solar system a couple of years ago.

As our vision gets clearer and our detectors more sensitive, the universe may come alive for us in exciting and unexpected ways!

Reference Links for Further Study:

Greenhouse gases could indicate alien life — if we ever find them
https://www.astronomy.com/science/greenhouse-gases-could-indicate-alien-life-if-we-ever-find-them/

Alien hunters should look for city lights from 'urbanized planets,' study suggests
https://www.space.com/alien-life-seach-city-lights-exoplanets

Astronomers find 60 Dyson sphere candidates, among millions of searched stars
https://earthsky.org/space/dyson-sphere-alien-megastructures-infrared-heat-stars/

A Study Says Warp Drives Might Be Real—and We'll Find Them With Lasers
https://www.popularmechanics.com/space/deep-space/a61193854/warp-drive-gravitational-waves/