Have we been looking for aliens in the wrong place this whole time?
Researchers are now seriously considering the possibility if they exist, we won't find evidence in outer space, but right here on Earth - only invisible to the eye.
"When we think of other intelligent beings, we tend to see them from our perceptive and conscience sieve; however we are limited by our unique vision of the world, and it's hard for us to admit it," says Gabriel de la Torre of the University of Cadiz in Spain.
He's proposed rather than looking for radio signals, gamma ray bursts and alien probes, scientists should be looking for signs of ET in dark matter.
Dark matter and energy are believed to make up 95 percent of the universe's total energy. The stuff we can see is only 5 percent.
It's not even a certainty that dark matter exists, but without it much of what scientists know about universe doesn't add up. Scientists believe dark energy is what's driving the universe apart, and dark matter is what's holding galaxies together.
They don't interact with the matter and energy we know of, except through gravity.
"What we are trying to do with this differentiation is to contemplate other possibilities - for example, beings of dimensions that our mind cannot grasp, or intelligences based on dark matter or energy forms, which make up almost 95 percent of the universe and which we are only beginning to glimpse."
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There could be dark matter passing through us right now, and unless we had state-of-the-art scientific instruments to measure it, we wouldn't even know.
"The fact that we use radio signals does not necessarily mean that other civilizations also use them, or that the use of energy resources and their dependence are the same as we have," says Dr de la Torre.
"We can have the signal in front of us and not perceive it or be unable to identify it... In fact, it could have happened in the past or it could be happening right now."
Gabriel de la Torre's ideas were published in the latest issue of scientific journal Acta Astronautica.