This site may earn chapter commissions from the links on this page. Terms of use.

deep field

Ever since scientists began to grasp the staggering calibration of the universe, we've wondered if there was other intelligent life out there. It certainly seems like there'southward space. No one has come calling from some other planet, or even sent a signal we can detect, though. This prompted famed physicist Enrico Fermi to speculate on the reason for this lack of contact. The so-called Fermi Paradox comes up whenever we talk nigh the search for life outside our solar organization, but what does the Fermi Paradox say about our place in the universe? It might predict our doom, or perhaps a bright futurity. It asks one elementary question: where is everybody?

The mathematics of loneliness

In the immortal words of Douglas Adams, "Space is big. You merely won't believe how vastly, hugely, listen-bogglingly big it is." We inhabit a planet orbiting a star that is just one of at least 100 billion stars in our Galaxy. The Milky Way is merely one milky way of… well, nosotros aren't sure. The old estimates were in the neighborhood of several hundred billion, but new data suggests in that location may be as many equally 2 trillion galaxies in the observable universe. And so, that's a whole lot of space.

From a sheer mathematical perspective, it seems likely that life of some sort would evolve on other planets out there. We know in that location are other planets, too — a lot of them. There's an interesting thought experiment known every bit the Drake Equation that can be used to estimate the number of detectable intelligent species. It includes factors for the number of stars, the probability of habitable planet formation, the development of intelligent life, and so on. You lot tin can encounter it below. Of course many of these values are complete guesses, but even if you plug very minor numbers into the Drake Equation yous come up with large numbers of detectable civilizations.

seti-drake-equation

In addition to being big, the universe is also extremely old. Our sun is four.5 billion years sometime, simply that'southward rather young. The universe itself is believed to have come into existence but shy of xiv billion years ago. There could be other planets around other stars that formed a billion or two billion years earlier u.s.. Imagine what a species a billion years more than avant-garde than united states would be similar. You lot tin can't really. Fifty-fifty a few centuries of progress on Globe has resulted in astonishing advances in technology. As Arthur C. Clarke pointed out, "any sufficiently advanced applied science is indistinguishable from magic."

In simply 100,000 years, humans take gone from tribal beings numbering in the thousands to the ascendant species on the planet with a population in excess of 7 billion. With a billion-year head outset, a species from another star could have expanded considerably more with engineering science we can't even brainstorm to imagine. Fifty-fifty if this hypothetical intelligence just decided to stay home and send self-replicating robotic explorers out into the galaxy, those robots would be everywhere by now.

Then, that leads u.s.a. to the large question: where is everybody?

The Great Filter

The first respond to that question is a troubling one. The math says there could be super-advanced civilizations given the calibration and age of the universe. So, mayhap at that place's nobody (or almost nobody) else in that location because intelligence like ours doesn't final long. Nosotros could be rare in the universe. This idea assumes what'southward known as The Great Filter, an evolutionary hurdle that few species articulate. So where's the filter? That'due south the troubling part.

Let'southward assume that we've already passed The Groovy Filter. Information technology'south more or less clear sailing for humanity now because we're one of the rare civilizations that made it — maybe the only i. Information technology doesn't really affair what The Great Filter is. All that matters is nosotros defied the odds and beat it, and that's why there isn't more than intelligent life out there.

It'due south too possible for in that location to be little intelligent life in the universe without a Not bad Filter. For this to be true, the only filter is the development of life. In this scenario, the atmospheric condition needed for intelligent life to develop in the universe were simply recently met. That means no ancient aliens with a billion year head first on u.s.a. ever existed. We would simply be ane of the first intelligences to ascend, and at that place could be others on the rise with us. I suppose you could telephone call this ane a positive scenario.

An asteroid hurtling towards Earth

For every best instance there's a worst 1 besides. That's what you'd call it if The Great Filter is ahead of united states of america. That means humanity is neither rare nor first in the universe, and there is some substantial evolutionary hurdle ahead of us that near no species can clear. That would explain why we oasis't seen any super-intelligent ancient aliens, because they are the rare ones — the precious few to clear The Great Filter. In this scenario, humanity is probably doomed. Mayhap an asteroid wipes us out earlier nosotros develop the applied science to deflect it. Or perhaps nosotros're running into The Bang-up Filter correct now, and it's climate change or the exhaustion of natural resources that knock well-nigh civilizations back.

Maybe they're everywhere

All that talk of The Smashing Filter is a bummer, but there's another potential answer to the Fermi Paradox that'south more upbeat. We might not be rare, just just oasis't been able to spot intelligent life yet. There could be many avant-garde civilizations in the universe that only don't want to accept contact with us for 1 reason or another.

When we wonder almost the motivations of aliens, nosotros presume they call up similar usa. That'southward far from sure, though. Perhaps the idea of exploring the cosmos is a uniquely human one. A hyper-advanced conflicting race might lock themselves upwardly tight in a Dyson Sphere and stay put. They may non have the aforementioned need to expand as their population grows similar humans practise, and so it'due south reasonable that we would never have seen evidence of them.

Another possibility in this realm is that intelligent life is so common that we're intensely uninteresting, and no advanced species would bother communicating with Earth. We could be in the galactic backwater of the Galaxy far away from all the important stuff. Aliens in this scenario might occasionally pass by and say, "look at those ape descendants, so slow and primitive." Or peradventure they aren't even physical anymore, having long since moved beyond the need for corporeal bodies. If they've uploaded their minds to some sort of communal super-intelligence, then the very thought of beings living on a planet could seem blasé.

dyson

A Dyson Sphere.

A darker version of aliens being everywhere is a science-fiction staple — space is a dangerous place, and broadcasting your presence is a bad idea. By making yourself piece of cake to find, you lot're inviting invasion by aggressive hyper-advanced aliens. That would explain why we don't see everyone — they're all keeping their heads downwardly because they know something nosotros don't.

Another possible explanation for a universe teeming with intelligence we tin't see is what I like to phone call the "Prime Directive" scenario. Hither, advanced alien life exists all around us, simply they are intentionally hiding themselves from lesser beings. In Star Trek, the Prime Directive dictates that humans non interfere with the internal workings of alien worlds. That means concealing their existence from primitive civilizations. Then, mayhap the aliens are watching us, but they don't want to be involved straight until nosotros're a bit more mature.

It'southward not unthinkable that the Fermi Paradox only exists equally an idea considering we aren't set up as a species. I don't mean that aliens are concealing themselves a la the Prime Directive. Consider this one last thing: What if intelligent life is common in the milky way, and the testify for it is all around the states? The just problem is we're non smart enough to realize it.

Check out our ExtremeTech Explains series for more than in-depth coverage of today'south hottest tech topics.