The late physicist Stephen Hawking repeatedly raised the alarm about the dangers of reaching out to extraterrestrial life, and new research has reignited debate over whether humanity is playing with fire by trying to make contact.
A recent commentary published in the Journal of Biomedical Physics and Engineering explores Hawking's warnings through a physics lens, suggesting that the risk of hostile alien life may not be as far-fetched as it sounds – and could become a reality sooner than we think.
Hawking believed that attempting to actively broadcast messages into deep space could have catastrophic consequences for humanity if intelligent aliens were to receive them.
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As the paper highlights, Hawking supported listening for alien signals but strongly opposed sending messages outwards, fearing that “direct contact with advanced alien civilisations would inevitably lead to the colonisation of Earth by aliens”.
While this might sound like something out of a sci-fi blockbuster, the paper points out that history is full of examples where technologically advanced civilisations have overpowered less advanced ones. If aliens were capable of reaching Earth, the authors note, “they must be far more advanced and have unimaginable and presently unattainable technologies”, giving humanity little chance of defending itself.
Despite the warnings, efforts to reach out to extra-terrestrial intelligence have continued. Scientists have already crafted messages intended to reveal Earth’s location, seemingly ignoring Hawking's advice.
According to the paper, space probes like Voyager 1 are travelling at astonishing speeds of 38,000 mph, but even at that pace, it would take tens of thousands to millions of years to reach potentially habitable exoplanets.
Any civilisation capable of making the journey to us, however, would likely possess propulsion far beyond anything humans can imagine — potentially allowing for first contact far earlier than many expect.
The commentary also explores whether Hawking’s fear of hostile aliens could be an example of what psychologists call the “intelligence trap”, where highly intelligent individuals can fall into flawed thinking through overconfidence or narrow assumptions. While his caution is understandable, the authors question whether it’s fair to assume extra-terrestrials would have motivations to conquer or exploit us, noting that peaceful or cooperative outcomes can’t be ruled out.
But the paper warns that sending a message into deep space is still a gamble we don’t fully understand.
With the Milky Way alone estimated to contain at least 100 billion planets, the odds of encountering intelligent life are not negligible. As the authors explain, broadcasting our location could be “a tactical mistake”, especially when the intentions of any advanced lifeforms remain completely unknown.
With discussions about interstellar communication accelerating and some experts warning that alien signals could reach us within decades, Hawking's words sound more urgent than ever. The question now is whether humanity should keep listening for signs of life – or whether silence might be the safest strategy after all.