Is the universe a graveyard? This theory suggests humanity may be alone

Ever since we've had the technology, we've looked to the stars in search of alien life. It's assumed that we're looking because we want to find other life in the universe, but what if we're looking to make sure there isn't any?

Here's an equation, and a rather distressing one at that: N = R* × fP × ne × f1 × fi × fc × L. It's the Drake equation, and it describes the number of alien civilizations in our galaxy with whom we might be able to communicate. Its terms correspond to values such as the fraction of stars with planets, the fraction of planets on which life could emerge, the fraction of planets that can support intelligent life, and so on. Using conservative estimates, the minimum result of this equation is 20. There ought to be 20 intelligent alien civilizations in the Milky Way that we can contact and who can contact us. But there aren't any.


The Drake equation is an example of a broader issue in the scientific community—considering the sheer size of the universe and our knowledge that intelligence life has evolved at least once, there should be evidence for alien life. This is generally referred to as the Fermi paradox, after the physicist Enrico Fermi who first examined the contradiction between high probability of alien civilizations and their apparent absence. Fermi summed this up rather succinctly when he asked, “Where is everybody"?

But maybe this was the wrong question. A better question, albeit a more troubling one, might be “What happened to everybody?" Unlike asking where life exists in the universe, there's a clearer potential answer to this question: the Great Filter.

Why the universe is empty

The Very Large Array in New Mexico consists of 27 radio dishes designed to capture information from cosmic phenomena, like galactic collisions, the birth of stars, and others. It was also the point of the first contact form the movie "Contact" (ROBYN BECK/AFP/Getty Images)

Alien life is likely, but there is none that we can see. Therefore, it could be the case that somewhere along the trajectory of life's development, there is a massive and common challenge that ends alien life before it becomes intelligent enough and widespread enough for us to see—a great filter.

This filter could take many forms. It could be that having a planet in the Goldilocks' zone—the narrow band around a star where it is neither too hot nor too cold for life to exist—and having that planet contain organic molecules capable of accumulating into life is extremely unlikely. We've observed plenty of planets in the Goldilock's zone of different stars (there's estimated to be 40 billion in the Milky Way), but maybe the conditions still aren't right there for life to exist.

The Great Filter could occur at the very earliest stages of life. When you were in high school bio, you might have the refrain drilled into your head “mitochondria are the powerhouse of the cell." I certainly did. However, mitochondria were at one point a separate bacteria living its own existence. At some point on Earth, a single-celled organism tried to eat one of these bacteria, except instead of being digested, the bacterium teamed up with the cell, producing extra energy that enabled the cell to develop in ways leading to higher forms of life. An event like this might be so unlikely that it's only happened once in the Milky Way.

Or, the filter could be the development of large brains, as we have. After all, we live on a planet full of many creatures, and the kind of intelligence humans have has only occurred once. It may be overwhelmingly likely that living creatures on other planets simply don't need to evolve the energy-demanding neural structures necessary for intelligence.

What if the filter is ahead of us?

These possibilities assume that the Great Filter is behind us—that humanity is a lucky species that overcame a hurdle almost all other life fails to pass. This might not be the case, however; life might evolve to our level all the time but get wiped out by some unknowable catastrophe. Discovering nuclear power is a likely event for any advanced society, but it also has the potential to destroy such a society. Utilizing a planet's resources to build an advanced civilization also destroys the planet: the current process of climate change serves as an example. Or, it could be something entirely unknown, a major threat that we can't see and won't see until it's too late.

The bleak, counterintuitive suggestion of the Great Filter is that it would be a bad sign for humanity to find alien life, especially alien life with a degree of technological advancement similar to our own. If our galaxy is truly empty and dead, it becomes more likely that we've already passed through the Great Filter. The galaxy could be empty because all other life failed some challenge that humanity passed.

If we find another alien civilization, but not a cosmos teeming with a variety of alien civilizations, the implication is that the Great Filter lies ahead of us. The galaxy should be full of life, but it is not; one other instance of life would suggest that the many other civilizations that should be there were wiped out by some catastrophe that we and our alien counterparts have yet to face.

Fortunately, we haven't found any life. Although it might be lonely, it means humanity's chances at long-term survival are a bit higher than otherwise.

How getting in sync with your partner can lead to increased intimacy and sexual desire

Researchers discover a link between nonverbal synchronization and relationship success.

Pixabay
Sex & Relationships
  • Scientists say coordinating movements leads to increased intimacy and sexual desire in a couple.
  • The improved rapport and empathy was also observed in people who didn't know each other.
  • Non-verbal clues are very important in the development stages of a relationship.
Keep reading Show less

How humans evolved to live in the cold

Humans evolved to live in the cold through a number of environmental and genetic factors.

Image source: Wikimedia Commons
Surprising Science
  • According to some relatively new research, many of our early human cousins preceded Homo sapien migrations north by hundreds of thousands or even millions of years.
  • Cross-breeding with other ancient hominids gave some subsets of human population the genes to contend and thrive in colder and harsher climates.
  • Behavioral and dietary changes also helped humans adapt to cold climates.
Keep reading Show less

Stan Lee, Marvel co-creator, is dead at 95

The comics titan worked for more than half a century to revolutionize and add nuance to the comics industry, and he built a vast community of fans along the way.

(Photo: GABRIEL BOUYS/AFP/Getty Images)
Culture & Religion
  • Lee died shortly after being rushed to an L.A. hospital. He had been struggling with multiple illnesses over the past year, reports indicate.
  • Since the 1950s, Lee has been one of the most influential figures in comics, helping to popularize heroes that expressed a level of nuance and self-doubt previously unseen in the industry.
  • Lee, who's later years were marked by some financial and legal tumult, is survived by his daughter, Joan Celia "J.C." Lee.
Keep reading Show less