Traces of alien technology may be how humans first discovered extraterrestrial life

Traces of alien technology may be how humans first discovered extraterrestrial life

Many human technologies, from cell towers to fluorescent lights, could become beacons of life if aliens were to see Earth.

We are two astronomers working on the search for Extraterrestrial Intelligence (SETI). Our research seeks to characterize and detect signs of technology originating from extraterrestrial origin.

These are called techno signatures. Scanning the skies for extraterrestrial Olympics TV broadcasts may sound simple, but looking for signs of distant advanced civilizations is a much more subtle and difficult task than one might think. .

Say “hello” with radios and lasers

Modern scientific investigation of extraterrestrial intelligence began in 1959 when astronomers Giuseppe Cocconi and Philip Morrison showed that radio telescopes could detect radio transmissions from Earth at interstellar distances.

That same year, Frank Drake launched the first SETI search, Project Ozma, by pointing a large radio telescope at two nearby Sun-like stars to see if they could detect radio signals from them. have started.

Following the invention of the laser in 1960, astronomers showed that visible light can be detected even from distant planets.

All these first basic attempts to detect radio or laser signals from other civilizations were intentionally sent into the solar system, looking for focused and powerful signals intended to be discovered. .

Given the technological limitations of the 1960s, astronomers weren’t serious about looking for broadcast signals leaking into space like they were with television and radio broadcasts on Earth.

But beams of radio signals with all their power concentrated at Earth can be detected from much greater distances. Imagine the difference between a laser and a weak light bulb.

Deliberate radio and laser signal searching remains one of the most popular SETI strategies today. However, this approach assumes that extraterrestrial civilizations wish to communicate with other technologically advanced life forms.

Humans rarely transmit targeting signals into space, and some scholars argue that intelligent races deliberately avoid making their locations public. This search for signals that no one may have sent is called the SETI paradox.

Radio wave leakage

Humans don’t often send intentional signals into space, but many of the technologies people use today produce many radio transmissions that leak into space. Some of these signals are detectable if they come from nearby stars.

A global network of television towers is constantly emitting signals in many directions, and these signals can leak into space and accumulate into relatively weak but detectable radio signals.

Research is ongoing as to whether current emissions from cell towers at terrestrial radio frequencies can be detected using today’s telescopes, but future square-kilometer array radio telescopes will emit 50 times more than current radio telescopes. Sensitivity allows you to detect even weaker radio signals. arrangement.

However, not all artificial signals are so unfocused. Astronomers and space agencies use radio beams to communicate with satellites and spacecraft in the solar system.

Some researchers are using radio waves for radar to study asteroids. In both cases, the radio signal is more concentrated and directed into space.

Extraterrestrial civilizations that happen to be within sight of these beams may detect these apparent man-made signals.

Discovery of megastructures

Aside from spotting real alien spaceships, radio waves are the most common technological feature featured in science fiction movies and books. But they aren’t the only possible signals out there.

In 1960, astronomer Freeman Dyson argued that since stars are by far the most powerful source of energy in any planetary system, a technologically advanced civilization would essentially be a giant solar panel, theorized that a significant portion of the light of

Many astronomers call these megastructures, and there are several ways to detect them.

After harnessing the captured light energy, the technology of advanced society re-releases some of the energy as heat.

Astronomers have shown that this heat can be detected as extra infrared radiation coming from the star system.

Another way to find megastructures is to measure their dimming effect on stars. Specifically, large satellites orbiting stars regularly block some of their light.

This is seen as a dip in the star’s apparent brightness over time. Astronomers can detect this effect, similar to how distant planets are discovered today.

heavy pollution

Another technical feature considered by astronomers is contamination.

Chemical pollutants such as nitrogen dioxide and chlorofluorocarbons on Earth are produced almost exclusively by human industry. It is possible to detect these molecules in exoplanet atmospheres in the same way that the James Webb Space Telescope uses to look for biological signatures on distant planets.

If astronomers find a planet with an atmosphere filled with chemicals that can only be produced by technology, it could be a sign of life.

Finally, artificial light or heat from cities and industry may also be detectable by large optical and infrared telescopes, as are many satellites orbiting the planet.

But to be detectable across the vast universe using the technology humans now possess, civilizations would need to produce far more heat, light, and satellites than Earth does.

Which signal is best?

No astronomers have ever discovered any confirmed technical features, so it’s hard to say what the first signs of an alien civilization might be.

Many astronomers have thought a lot about what would be a good signal, but ultimately no one knows what extraterrestrial technology looks like or what signals there are in space. not.

Some astronomers advocate a generalized SETI approach that searches for anything in the universe that cannot be naturally explained by current scientific knowledge. Some, like us, continue to search for intentional and unintentional technical signatures.

The bottom line is that there are many means to detect life at great distances. No one knows which approach is likely to succeed first, so there is still a lot of exciting work to do.

Macy Houston and Jason Wright, Pennsylvania (The Conversation)

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