Finding Aliens: Why It Might Be Terrible News#

Imagine this: NASA announces today they found aliens! They found bacteria on Mars, weird alien fish in the oceans of Europa, and ancient alien ruins on Titan. Sounds amazing, right?

Well, actually, no. It would likely be horrible news, even devastating. It could mean that the end of humanity is almost certain and might be coming soon.

But why? Why would the most exciting discovery of our lives be a bad thing?

The Staircase of Life#

Let’s think about how life develops, from when it first starts all the way up to where we are now. Imagine it like climbing a flight of stairs.

• Step 1: Dead chemistry has to somehow put itself together into things that can copy themselves. These self-copying things need to be strong enough to last but also able to change and get better over time.
• Step 2: Early life needs to get more complicated. It learns to build more complex stuff and use energy from its surroundings much more efficiently.
• Step 3: These cells join up to become many-celled beings. This allows for incredible variety and even more complexity in life forms.
• Step 4: Species develop big brains. This lets them use tools, build cultures, and share knowledge, leading to even higher levels of complexity. At this point, a species can become the top life form on its planet and change the planet to suit its needs.
• Current Step (Where We Are): This species starts making its first shy attempts to leave its home planet.

Life, as we understand it, naturally wants to spread out and fill every possible space, every “niche.” Since planets can only hold so much life and don’t last forever, a species that wants to survive will look for new places to go.

So, the steps that seem logical after where we are now are:

• Colonize your own solar system.
• Spread out even further to reach other stars.
• The possible final step: Become a civilization that exists across the entire galaxy.

This idea of spreading out is probably a universal rule for civilizations, no matter where they come from. If a species is driven and competitive enough to take control of its planet, it’s unlikely to just stop there.

The Mystery of the Empty Galaxy#

We know there are tons of planets out there – up to 500 billion in the Milky Way galaxy alone, and at least 10 billion of them are thought to be like Earth. Many of these planets have been around for billions of years longer than Earth has.

Given all this, you’d think we’d see something… some sign of galactic civilizations. But when we look out, we see zero. Absolutely nothing.

Space looks empty and dead at the civilization level.

This leads to a big conclusion: Something is stopping living things from climbing this staircase much beyond the step we’re on right now. …Something that makes becoming a galaxy-wide civilization incredibly difficult, maybe even impossible.

This is what we call The Great Filter.

What is The Great Filter?#

The Great Filter is a challenge or danger so enormous and hard to overcome that it wipes out almost every species that runs into it.

This leaves us with two main possibilities, two scenarios:

• Scenario 1: We are incredibly special and lucky.
• Scenario 2: We are pretty much already doomed and practically dead, just haven’t hit the wall yet.

Which scenario is true depends on where this Great Filter is located on our staircase: Is it already behind us, or is it still ahead of us?

Scenario 1: The Filter is Behind Us#

If the Great Filter is behind us, it means we are likely the first or among the very few to have made it this far. This would mean that one of the steps we’ve already passed was almost impossible for life in general to achieve.

Which step could it have been?

• Is life ITSELF extremely rare?

  • It’s really hard to guess how likely it is for life to start from just dead chemistry (this is called abiogenesis).
  • There’s no agreement among scientists. Some think life pops up everywhere the conditions are right. Others think Earth might be the only place with life in the whole universe.

• Was the step of complex animal cells the filter?

  • Something very specific and strange happened at this point in life’s development.
  • As far as we know, it happened exactly once on Earth.
  • A simple cell that hunted others basically swallowed another cell but didn’t eat it. Instead, they formed a partnership.
  • The bigger cell offered safety and handled dealing with the outside world, getting resources.
  • The smaller cell, using its new home and free stuff, focused on creating lots of extra energy for the bigger cell.
  • With all this extra energy, the host cell could grow bigger and build new, complex things to improve itself. The swallowed cell became like the “powerhouse” of the combined cell.
  • These kinds of cells make up every single animal on our planet.
  • Maybe there are billions of planets covered in simple bacteria in the Milky Way, but not a single one, besides Earth, managed to achieve this level of complexity.

• Is intelligence the filter?

  • Or maybe the filter was the step of becoming intelligent?
  • We humans feel pretty smart and advanced with our books and clever ideas.
  • But having a big brain is a really expensive thing for evolution to invest in.
  • Brains are fragile, they don’t help you win a physical fight with a bear, and they use up enormous amounts of energy.
  • Despite having big brains, it took modern humans 200,000 years to get from using sharp sticks to building civilizations.
  • Simply being smart doesn’t guarantee you’ll win and succeed automatically.
  • Maybe intelligence just isn’t that great for long-term survival, and we were just lucky that it worked out for us.

If the filter is behind us, it means we got incredibly lucky to pass a step that almost no one else could.

Scenario 2: The Filter is Ahead of Us#

If the Great Filter is ahead of us, it means that plenty of other advanced species in the galaxy have probably died already, hitting this barrier before reaching our current stage or beyond.

A Great Filter in our future would be vastly more dangerous than anything humanity has faced so far. Even a massive disaster that killed most people or sent us back to the Stone Age wouldn’t be the filter. If we could survive and eventually recover, even over a million years, that’s just a big setback, not a Great Filter preventing galactic civilization altogether. On the scale of the universe, a million years is just a tiny moment.

For a Great Filter to really lie ahead of us, it would have to be something so destructive, so incredibly powerful, that it has wiped out most, if not all, advanced civilizations in our galaxy over billions of years.

Here’s a really worrying idea: Maybe once a species takes control of its planet, it’s already on the path to destroying itself. Technology could be the way this happens. The filter would need to be something so obvious that virtually every advanced civilization discovers it, and so dangerous that discovering it almost always leads to an end-of-the-world scenario for that species.

What could these future filters be?

• A huge nuclear war.
• Nanotechnology that goes out of control and consumes everything.
• Creating a perfect super-bug through genetic engineering that wipes us out.
• An experiment that accidentally sets the entire atmosphere on fire.
• A super-intelligent AI that destroys its creators, either by mistake or on purpose.
• Or maybe it’s something we can’t even imagine right now.

Or, it could be much simpler: Maybe species that are competitive enough to take over their planet end up destroying the planet itself while fighting each other for resources. Perhaps there are environmental chain reactions built into every ecosystem that, once started by an advanced civilization, cannot be stopped or fixed. So, once a civilization is powerful enough to change its planet’s atmosphere, for example, they make their planet completely uninhabitable, 100% of the time.

Let’s really hope that isn’t the case. If the filter is ahead of us, our chances of long-term survival look very, very bad.

Why Finding Life Beyond Earth Would Be Horrible#

This brings us back to the beginning. THIS is why finding life beyond Earth would be bad news.

The more common life is in the universe, and the more advanced and complex we find it to be, the more likely it becomes that the Great Filter is still in front of us.

• Finding bacteria would be bad.
• Finding small animals would be worse.
• Finding intelligent life would be truly alarming.
• Finding ruins of ancient alien civilizations… that would be absolutely horrible, strongly suggesting the filter is something we haven’t hit yet but will.

The best-case scenario for humanity right now is that Mars is lifeless, that Europa’s oceans are empty, and that the vast areas of the Milky Way galaxy are just empty oceans next to dead continents.

…That there are billions of empty planets out there, just waiting to be discovered and filled up with life. Billions of new homes… waiting for us… to finally arrive.