Why haven't aliens contacted us? Here's what a NASA-based scientist says

Over the past few decades, scientists have discovered thousands of exoplanets, and our galaxy alone is thought to contain hundreds of billions of planets. Interest in extraterrestrial life has also grown with reports of UFO sightings and the U.S. government's release of data on unidentified aerial phenomena. Yet despite all this, we still have no evidence of life beyond Earth. So, are we simply unable to find extraterrestrial life, or do advanced civilizations not want to be found? Scientists have proposed several possible explanations over the years. Here's a look at what one NASA scientist believes. 

NASA hasn't found life on any other planet, and there's no scientifically supported evidence of extraterrestrials yet. But on Earth, microbial life turns up almost everywhere we look, even in places once thought too extreme to support it. NASA has sent five rovers and four landers to Mars, though we've explored only a tiny fraction of it. Moons like Enceladus and Europa may hide subsurface oceans. As astronomer Carl Sagan said, "The universe is a pretty big place. If it's just us, it seems like an awful waste of space."

Dr. Robin Corbet, a senior research scientist at the University of Maryland, Baltimore County, based at NASA's Goddard Space Flight Center, has proposed an idea he calls "radical mundanity." Instead of thinking that aliens are far more advanced than us, this theory suggests that they are only slightly more advanced than us. He noted, "The idea is that they're more advanced, but not much more advanced. It's like having an iPhone 42 rather than an iPhone 17. This feels more possible, more natural, because it's not proposing anything very extreme."

Corbet says that extraterrestrial civilizations (ETCs) could theoretically send out a high-powered beacon or robotic probes to make contact with other worlds. But this would require an enormous amount of power, and any reply could take millions or even billions of years to arrive. Given that, he says there's little motivation for any civilization to keep trying. Earth's biosphere is also unique, and the oxygen we breathe could be highly corrosive to alien life. That means, just as we wear spacesuits when exploring inhospitable environments like space, extraterrestrials might also need protective gear to visit our planet.

If a reasonable number of ETCs exist in the galaxy, Corbet believes Earth is likely seen as unremarkable, which lowers the odds of an alien invasion. He does think there's a "reasonable chance" of contact happening within a relatively short, historical timescale. But he cautions that detecting an ETC probably wouldn't push our own technology forward much, since the two civilizations would be at similar levels. But there's another possibility. They may have already found us but simply don't want to interact. That's the idea behind the Zoo Hypothesis by John A. Ball, a Harvard astrophysicist, which says that advanced alien civilizations intentionally keep their distance so humans can develop naturally without interference. 

Even though this study offers a fresh perspective, it hasn't convinced everyone. Commenting on this, Prof. Michael Garrett, director of the Jodrell Bank Centre for Astrophysics, said, "It projects a very human-like apathy on to the rest of the cosmos. I find it hard to believe that all intelligent life would be so uniformly dull." Garrett instead favors the idea that advanced civilizations evolve beyond biology, advancing so rapidly that they become far beyond our capability to detect them altogether. “I hope I’m right, but I could very well be wrong. Nature always has some kind of surprise for us around the corner,” he added.