If the internet has taught us anything, there are plenty of people who absolutely freak out about aliens. That club includes one of the smartest people alive: Stephen Hawking, who has been anything but shy about expressing strong fears that a hostile alien civilization could one day blow up humanity to smithereens.

What gives? Hawking is part of a growing number of scientists who think intelligent extraterrestrial life isn’t just real, but probably a lot more common than we might assume. But unlike many of his more optimistic scientist-celebrity colleagues, Hawking thinks contact with aliens would probably spell doom for our species. In fact, he advocates slinking back into the background and keeping our presence in the universe shrouded until we have a better understanding of how to deal with alien affairs.

Eternally optimistic Seth Shostak has the opposite point of view. The director for the Center of SETI Research at the SETI Institute in Mountain View, California published an opinion piece in The Guardian on Tuesday rebutting Hawking’s ideas about hostile aliens, (most recently expressed in the new film Stephen Hawking’s Favourite Places).

Shostak acknowledges that sure, aliens might be dangerous: “We have no clue as to the intentions of putative extraterrestrials … ” he wrote. “Perhaps they live in a utopian Shangri-La similar to the one we’ve always said we want for ourselves, a place that values peace as well as the neighbours.”

To refrain from broadcasting our existence in the universe would be to err on the side of caution. However — and I can’t really stress this hard enough — that kind of action checks 200,000 years of human history that has resulted in our species pursuing the ends of the earth for the sake of exploration and adventure. Hell, Elon Musk just announced plans for how SpaceX intends to send humans to Mars, because there’s “a tremendous sense of adventure” to be had.

But Shostak also makes a very critical point: It’s too late. “Since the second world war,” he wrote, “we’ve been broadcasting television, high-frequency radio, and – most conspicuously – radar into the heavens. Little of this is done with the intention of either entertaining or notifying aliens, but is simply an inevitable leakage of radio transmissions into space.”

However, those signals are weak, and would have to travel light-years’ distance in order for an intelligent alien species to detect them.

That’s not even the biggest limiting factor to a race intent on seeing our destruction. Interstellar travel is really hard, and even with advanced technology, it would still take a long time for aliens to reach us from across the galaxy or from another galaxy entirely.

Moreover, there’s the fact that being suspicious of extraterrestrials is simply a sad way for us to go about exploring the universe. For too long, the term “alien” has been used as a pejorative, connoting something strange and foreign, met with suspicion and derision. Hawking’s pessimism feeds into those fears and stifles our more enthusiastic inclinations to learn more about the universe and embrace the unknown.

Thankfully, while Hawking may be the most prolific scientist urging caution about SETI ventures, he’s in the minority. Other researchers are locked in arms with Shostak and instead promoting a sunnier outlook at the idea of finding intelligent alien life. After all, what could possibly be a more exciting and consequential discovery than learning humans are not alone in the universe?

Hawking’s position is strange, given that he’s the de facto face of the Breakthrough Starshot initiative, which seeks to successfully send spacecraft out into interstellar space and investigate the Alpha Centauri star system for life and habitable worlds. But there’s actually a good argument to be made that apocalyptic fears are what drove Hawking to sign up with Breakthrough in the first place. If humanity is likely going to drive itself into oblivion by staying here on Earth, it’s probably better to take our chances with running into hostile aliens and become a star-faring species.

Shostak, too, believes humanity’s days here on Earth are numbered, but not because we’re headed towards outright extinction. Instead, he suggests the interplay of humanity with biotechnology, A.I., and outer space will push us to evolve into something that is perhaps very unlike what a human being currently is — but our descendants will be better off for it.

It’s a shame Hawking cannot share such a sentiment. His ideas seem to originate based on existential fears of the future that pick at the worst aspects of life — here or elsewhere. He might benefit, instead, to think not about what humanity has to do to survive, but what it can do to flourish.

Photos via Getty Images / Bryan Bedder