These 4 signs of alien technology could lead us to extraterrestrial life

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Project Galileo is a new mission that will stalk our solar system and beyond for remnants of extraterrestrial civilizations. Whether it’s potential extraterrestrial probes – like ‘Oumuamua – or even a distant megastructure, these signs of extraterrestrial life will completely change our place in the Universe.

Megastructures

Alien megastructure © Getty Images

Just as our global energy needs keep increasing, so will the energy needs of an advanced extraterrestrial civilization. In 1960, British-American physicist Freeman Dyson suggested that eventually extraterrestrials (ETs) will want to use all of their parent star’s energy output.

They could do this, he argued, by dismantling their asteroid belt and reconstructing it as a spherical shell that completely encloses their sun. Not only would this provide huge amounts of power, but it would provide a huge surface area – the inside of the shell – for living space.

A Dyson Sphere would be unstable, but an equatorial belt or a vast constellation of satellites could still intercept huge amounts of stellar energy. Such a structure might be detectable because the laws of thermodynamics predict that intercepted starlight is emitted as thermal or far-infrared radiation.

Also, a large number of bodies orbiting a star could eclipse its light, causing it to fluctuate wildly. This has been seen in the case of KIC 8462852 or ‘Tabby’s star’. Although this has been explained by dust in our own solar system, the possibility remains that the light from other stars could be variable in some unusual way and only explainable by nearby orbiting megastructures.

Industrial chemicals

Industrial chemicals © Alamy

Human civilization is injecting polluting chemicals into Earth’s atmosphere, and alien civilizations may do the same. Such chemicals are not only potentially detectable, but also unambiguously of intelligent origin.

If we observe a planet in a solar system beyond our own, as the planet moves between us and its parent star, starlight will pass through its atmosphere and bursts of light will be shed at wavelengths characteristic of atmospheric chemicals. This allows astronomers to detect what substances are present in the planet’s atmosphere.

According to Professor Avi Loeb, an astrophysicist, some promising industrial chemicals to look for in these extraterrestrial atmospheres are tetrafluoromethane (CF4) and trichlorofluoromethane (CCl3F). Both of these chemicals are refrigerants and are the two easiest chlorofluorocarbons (CFCs) to detect.

“If CCL3F and FC4 exist at 10 times current Earth levels, they should be detectable in 1.2 and 1.7 days of observation, respectively, with the James Webb Space Telescope [which was launched on Christmas Day 2021]explains Loeb.

Light sails

Dinghy sailing © Science Photo Library

Extraterrestrials will face the same problem as us if they cross interplanetary or interstellar space. Large amounts of fuel are required to drive a spacecraft. But this problem disappears if the spacecraft power source is left at home.

It was the proposal of Robert Forward of Hughes Research Laboratories in Malibu, California. In 1984, he described a lightweight laser-driven sail. A payload would be attached to a large, ultra-thin sail of reflective material and this would be pushed by a solar-powered laser based in the solar system. Forward calculated that a one-ton probe attached to a 3.6 km wide light sail could be accelerated by a 65 GW laser to 11% of the speed of light and fly by the nearest star system. , Alpha Centauri, in just 40 years.

This idea was recently taken up for the Breakthrough Starshot program. It’s at an early stage, but the goal is to use a 100 GW laser array to push a much more modest one gram (!) payload at 20% the speed of light and hover and photograph the planet around Proxima Centauri.

If aliens use similar laser-pushed light sails to circumvent their planetary systems or the galaxy, we may be able to pick up flashes of light as their lasers are turned on and off.

Wormhole transport systems

Gravitational lens © Alamy

A sufficiently advanced civilization might be able to manipulate spacetime itself to create wormholes. These shortcuts through spacetime – enabled by Einstein’s theory of gravity – could make it possible to traverse a galaxy in the blink of an eye.

Intrinsically unstable, a wormhole would need “stuff” with repulsive gravity to keep each mouth open, and the energy equivalent to that emitted by a sizable fraction of a galaxy’s stars. We know such things exist because they are accelerating the expansion of the Universe under the guise of dark energy, although its gravity is too weak to open a wormhole.

If aliens have created a network of wormholes, it could be detectable by gravitational microlensing. It happens when a celestial object passes between us and a distant star and its gravity briefly amplifies the light from the star.

If the object is a wormhole, the star’s brightening and fading pattern is markedly different, according to Professor Fumio Abe of Nagoya University in Japan. “If wormholes have throat radii between 100 and 10 million kilometers, are bound to our Galaxy, and are as common as ordinary stars, detection could be achieved by reanalyzing past data,” he says.

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