Earth’s radio signals have only reached about 15,000 stars—barely a blip in the Milky Way.
Key Takeaways:
- Aliens might ignore planets with just life and look for technological signals instead.
- Earth’s radio waves have only reached a tiny portion of the Milky Way.
- Only civilizations within 50 light-years could have had time to respond.
- Early radio signals were weak and likely unintelligible to aliens.
- The chances of contact increase as Earth continues broadcasting signals.
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Why Haven’t Aliens Reached Out?
A new preprint study by Amri Wandel, an astrophysicist at The Hebrew University of Jerusalem, suggests that intelligent extraterrestrials might be ignoring Earth—not because they don’t exist, but because they don’t see anything interesting here. The paper, published on the arXiv database and awaiting peer review, explores a fresh angle on the Fermi paradox, which questions why, given the vastness of the universe, we haven’t detected signs of intelligent alien life.
The study proposes that if life is common in the Milky Way, then advanced civilizations are likely looking for technology, not just biology. If Earth were one of many planets with microbial life, aliens wouldn’t waste time trying to communicate with simple organisms. Instead, they would seek out planets that broadcast clear technological signals.
Are Our Signals Too Weak?
Earth has only been sending out radio signals detectable from space since the 1930s. In that time, these signals have spread out to roughly 15,000 nearby stars—a tiny fraction of the galaxy’s estimated 400 billion stars. Moreover, the earliest signals were not intentionally aimed at space and may have become too weak and distorted to be recognized by distant civilizations.

Wandel calculated that unless the Milky Way hosts at least 100 million technologically advanced civilizations, it’s unlikely that Earth’s signals have been picked up. Since radio waves take time to travel, only civilizations within 50 light-years of Earth could have received and responded to our transmissions by now. If no one within that range has replied, it doesn’t mean intelligent life isn’t out there—it just suggests we may have to wait longer to get a response.
Some scientists believe we should take a more proactive approach, like sending new high-power messages into space. The Arecibo message, a deliberate transmission aimed at the M13 star cluster in 1974, was one such attempt. But so far, we have yet to receive a reply.
Waiting for a Call
Ultimately, the study implies that intelligent life may still be out there but hasn’t noticed us yet. As Earth continues broadcasting signals into space, the likelihood of reaching an advanced civilization increases. If extraterrestrials exist beyond the 50-light-year range, we may simply need more time before they recognize our presence and decide to respond. Until then, the search for intelligent life continues.