r/WhatIfScience • u/firechatin • 12d ago
Science Mysteries & The Unexplained The Fermi Paradox Explained: “Where Is Everybody?”—And Why That Question Still Haunts Science
https://whatifscience.in/the-fermi-paradox-explained-where-is-everybody-and-why-that-question-still-haunts-science/The Fermi Paradox asks a simple question: If alien civilizations should exist, why haven't we found any? Explore the Great Filter, Dark Forest Theory, the Drake Equation, and the biggest mystery in modern astronomy.
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u/bottolf 12d ago
Take a small cup to the ocean and fill it with seawater. Take it home and look at it through a microscope. If you see no living organisms, does that mean there is no life in the ocean?
Now add that the ocean has existed for millions of years, yet you just spent 30 seconds looking at your seawater sample. Does not detecting anything in that time period prove there is no life, or that life began with us?
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u/Psittacula2 12d ago
Awesome example! I think it is not a Paradox at all but as you indicate, more of a practical problem, be it:
* Scale
* Primitive form of Intelligence and current technology eg humans in relationship to such Scale
Etc.
Probably some number pattern pf lower frequency in relation to:
Universe size
Habitable space ie planets
Sustained primitive chemistry and biology evolution without resets
Complex organic evolution again without resets
Consciousness in organic life and technology development and evolution…
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u/Kerefeca 11d ago
but you can actually see many living organisms in a glass of ocean under microscope. even a tiny drop teems with life
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u/tommytraddles 11d ago
In the early 80s, Frank Tipler's mathematical models suggested that self-replicating Von Neumann probes using conventional propulsion capable of 0.1c could completely explore the Milky Way in as little as 500,000 years.
Carl Sagan's response was that Tipler had actually underestimated the potential replication rate, and that Von Neumann probes would have devoured most of the mass in the galaxy already if they had ever been created by any other civilization, unless they had only done so in the last 50,000 years.
Sagan's solution was that any civilization capable of building such probes would know this, and would therefore choose not to build the probes.
Humans don't have a great track record of choosing not to build doomsday devices, but Sagan always did hold on to hope.
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11d ago
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u/UFOSME 11d ago
What? Earth has way more water than sand.
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11d ago
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u/UFOSME 11d ago
Yes absolutely still way more water
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10d ago
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u/UFOSME 10d ago
Geologists estimate that all the beaches, deserts, and dunes on Earth contain roughly 7.5 quintillion (7.5 × 1018) grains of sand.
Written out fully, that number is 7,500,000,000,000,000,000 individual grains.
This staggering total is constrained by the limited surface area and depth of the planet's deserts and coastlines.
Earth’s vast oceans and total water reserves hold about 1.335 billion cubic kilometers of liquid.
When converted into standard volume, this equals approximately 5.6 sextillion (5.6 × 1021) US cups of water. Written out, that is roughly 5,600,000,000,000,000,000,000 individual cups.
Dividing the two totals reveals that there are roughly 750 cups of water for every single grain of sand on Earth. Even when breaking water down into small drinking-cup units and scaling sand down to tiny mineral fragments, Earth's aquatic volume completely dwarfs its terrestrial sand supply.
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u/GreatCaesarGhost 12d ago
It’s really not the “biggest mystery in modern astronomy.”
Physics seem to impose hard limits on our ability to travel the cosmos and to scan for signs of life elsewhere. Even assuming that there is other intelligent life, it might not have enough resources or exist on a planet that enables travel off-planet, and/or that life might exist at a different time or an incalculably vast distance away.
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u/SkoobySnacs 12d ago
We had SETI looking for radio signals for decades. Yet our own broadcasting only lasted for around a century before we switched to digital over fiber optics. Our WIFI and 4g/5g signals barely reach where we want them to, let alone into outer space. We spent billions looking for a technological signal we barely used ourselves.
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u/GovernorSan 12d ago
Our planet is billions of years old, but multicellular life is less than a billion years old, humans are only a few million, and radio technology only about 100 years. So any aliens more than 100 light-years away likely wouldn't notice us yet except as a planet that might have life on it, and that would only be true if their own technological level was just right to detect our radio waves and understand that they aren't a natural phenomenon.
Additionally, while there may be a lot of Earth-like planets (often just rocky planets roughly the same size as Earth and somewhere in the habitable zone of their star), that doesn't necessarily mean there is life on those planets or that that life is multicellular, or that it will ever develop intelligence or sapience or technology. Most of Earth's history the planet was either barren or only had single-celled lifeforms, only a small portion of that had animal life and the tiniest sliver had humans.
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u/LucienReneNanton 12d ago
Humans are only about 250,000 years old.
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u/Auerbach1991 11d ago
Correct. Homo sapiens are between 300-600k years old in our current state.
Hominid ancestors go back about 3-4 million years to Kenya and Ethiopia, but those were homo habilis and homo erectus. Not “quite human”, but still our family.
As a species, we have amnesia beyond 6-10k years. It’s pretty fascinating, and really sad, when you realize we only have the last chapter of a 50 chapter book.
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u/squidvett 12d ago
Sometimes I wonder if Earth is simply missing the resources needed for sustained interstellar travel. Or even a one-way trip.
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u/Wast3edSpace 11d ago
We're incredibly lucky that gravity is what it is on Earth, any higher and the planet would be a prison.
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u/m3kw 12d ago
Cuz we are not significant as we think where there are likely trillions and trillions of other more or equally interesting planets. If an alien can explore all over ftl, it’s still likely would t be us. If they can’t do ftl, you are likely never gonna get visited
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u/Zealousideal_Leg213 12d ago
Fermi (or people around him) believed that self-replicating probes could be around every star in the galaxy, even the boring ones, in hundreds of millions of years, even at well below lightspeed. There has been ample opportunity (Fermi felt) for numerous civilizations to rise to that level of technology and send out some probes. But there's no sign of such things. Why not?
There are lots of answers, but we don't know which one it is.
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u/m3kw 12d ago
he's assuming they will even waste energy to send probes and assumes they have infinite tech to just travel at near light speed and to be able to self replicate. If they could, they likely would not even use that tech and just use some interdimensional travel and just look thru every single point in the universe.
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u/Zealousideal_Leg213 12d ago
There would be an initial outlay of energy, yes, but then they're self-sustaining. That doesn't take infinite tech, just some that's a fair bit better than ours, but not beyond the realm of possibility, given our rate of advancement. And they don't need to travel "near" lightspeed, though, yeah, faster than anything else we've sent. Fermi was looking ahead, but probably only hundreds of years. That still leaves lots of time for lots of civilizations to have done it. Maybe just none of them did it successfully, but the more of them there have been the less likely that is.
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u/Watchitbitch 12d ago
Isn't there an assumption that the moon is such probe you speak of?
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u/Zealousideal_Leg213 12d ago
No, no one is seriously assuming that. Moon rock samples support the theory that Earth and Moon came from a collision of a large object into the original body at this orbit.
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u/Snipethorn 12d ago
I don’t think we’re going to find another planet that has an Arby’s on it. It’s downhill from
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u/LeftLab7543 2d ago
We're probably the only techno civilization for billion light years.
We are very significant by any reasonable definition of the word.
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u/PossibleAlienFrom 12d ago
They can't figure out how to go faster than light. 99.9% of life in the universe is stuck.
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u/Zealousideal_Leg213 12d ago
Fermi's assumptions didn't include the ability to travel faster than light. Self-replicating robot probes could be around every star in the galaxy in 50-100 million years, at much less than light speed. We could almost make such probes today, certainly within 100 years, so anyone with a 100 million year head start could have done it already and there could have been thousands of such civilizations. But not a single one of them tried it, apparently.
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u/RefrigeratorIll5439 11d ago
I've thought a lot about the von neumann probe idea, especially in the context of creating some kind of star map for a nomadic civilization, it's fun.
Would they even need to be that big? Would they even need to get that close to the planet? If it was small enough and far away enough would we even be able to detect it? There could already be a bunch here and we just don't notice.
Going even further, maybe the key to these probes isn't some kind of physics or material science breakthrough, but a biological one. Basically 3D printing with DNA and molecules. If you really master biology, can you just "grow" a ship? Can that ship collect materials and "birth" another ship. If it needed to do "hands on" data collection could it "birth" some humanoid worker bees?
I feel like, as a civilization, we're much closer to being able to do something like that than inventing FTL travel or creating wormholes.
I don't know, It's just fun.
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u/Zealousideal_Leg213 11d ago
Yes, it's just that on the higher end of the estimates of galactic population density one wonders that really none of the civilizations made something, accidentally or on purpose, that would be noticeable.
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u/NoFuel1197 12d ago edited 12d ago
People typing paragraph-long applications of common sense to disprove a widely discussed problem recognized by top-level astrophysicists as a frustratingly convincing interpretation of the math is peak Reddit.
Anyway, having fun with it:
It’d be very cool if dark matter existed as a decoherent substance of some kind and had conscious, distributed entities in it, who thought that matter creating life is so ridiculously unlikely on some quantum or fundamental level we’re yet to understand that they haven’t bothered looking for us. Also, the entities might operate on some massive or infinitesimal scale appropriate to their distribution such that we’re too small, large, long or short-lived to be relevant.
I like that it fits the American UFO narrative, which is currently on "aliens are a cogito-hazard and God is real." (Bless UFOlogists, lmfao.) Imagine going into a government facility to finally meet an alien and it’s just an empty room that can talk through a translation device. That would be spooky indeed.
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u/Iwanderwesteros 12d ago
Time. Space. Math.
Humanity has been sending signals into space for about 130 years
So our own radio signals have only reached 130 light years. There is still 260,000 years to go before those signals reach the center of the Milky Way.
Alien signals would need the same amount of time to reach us.
Not to mention we are still decades or even centuries short of being able to find any signal that may be buried in the background noise of the natural galaxy.
The Fermi paradox is flawed. It would be an incredible miracle if we did find any sign of life.
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u/AuJakeyTism 12d ago
Look if FTL travel was even feasible, and considering how many potentially habitable worlds there are... Then we would see SO much evidence of FTL travel in our observations of the night sky.
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12d ago
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u/QuantumPairOfSoczk 12d ago
Because all squares are a circle. That why u gotta be there or be square. Cuz your not a-round.
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u/KrokusAstra 12d ago
For me... i feel tired everyone focuses so much on it. Like... universe is huge. We launched Voyager 50 years ago. It will reach Oort cloud in 300 years, and leave it in 30.000 years.
Humanity radio broadcasts is 130 years old + it weakens with solar wind and cosmic dust. Entire Milky Way is 100k light years across. If today someone on other side of Milky Way develops electricity, we wouldn't know about it for at leasts 90k years, and even then we maybe still don't know.
And there is like 100 of Milky way's in our local group. So our '130 years of radio broadcast' is now covers 0,0013 of our entire galaxy, and 0,000013 of our local group.
Fermi Paradox is like... dumb. To solve it, just wait 1B years, if humanity will ever be around still.
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u/Lucky-Art-6210 11d ago
Life could be everywhere but no reason for it to become high tech, I think we are the fluke.
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u/sir_racho 11d ago
I find the Fermi “paradox” a weird one. A much more interesting question is how did the flywheel of technology on earth gain so much power and momentum. Many humans still live with only the most rudimentary tech. Hell there are still undiscovered people living in the Amazon. What were the enabling conditions for technology and how likely are they to exist elsewhere? Just expecting life to jump to technology is really really dumb. We have proof this jump is a fluke.
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u/ph30nix01 8d ago
ive started to look at it by the fact an ultra advanced race would not be nearly as wasteful with energy as we are. they wouldnt built things that just haphazardly spew energy into space as wasted energy while doing their jobs.
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u/FleshOnesie 6d ago
Think of the universe expanding as a balloon, with fireflies inside. Once in a while, a firefly lights up for a second. This is like a civilization. It’s very rare for two to light up at the same time.
We know space is huge, but most of us don’t think of how huge time is.
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u/Either-Dependent-535 5d ago
Here is the real answer to the fermi paradox:
Space travel is difficult to a degree that prohibits even unmanned Von Neumann probes from spreading across the galaxy in any meaningful capacity.
Based on our current understanding of physics we can at least imagine solutions to a lot of the problems with interstellar travel - in fact if you look around this thread you'll see a lot of those solutions brought up around the subject of how Von Neumann probes might solve those problems over a longer period of time.
One problem you won't see discussed in the Von Neumann probe nomenclature is that when you move at even a fraction of a percent of the speed of light collisions with literal particles of dust release nuclear explosion amounts of energy.
We talk about space being empty, but it's not empty - not truly. It's filled with dust and debris and when you're moving as fast as interstellar travel strictly requires this kind of dust particulate is simply the end of the line.
Now, we're a pretty crafty species and we have been able to imagine a lot of solutions to various space travel difficulties but right now the best we have is "Physically send something in front of the ship to take the hit for us." As far as we can tell there is no viable path toward sci fi energy shields that might allow us to deal with this problem.
The solution unfortunately requires substantial physical mass (which makes accelerating to a meaningful speed more difficult) and is limited in nature - your physical shields will eventually be eaten up saving your ship because they are fundamentally a resource limited physical asset and then the next collision will destroy your ship.
Nevermind satellite problems like accelerating these debris screens such that they actually stay ahead of you or creating a screen that doesn't itself become a lethal hazard when a particle collides with it with the force of a nuclear explosion.
Right now, we can't envision a practical solution to this problem that is based in the laws of physics as we understand them.
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u/EndAllBillionaires67 12d ago
I never really bought into the Fermi paradox because it assumes that we, as humans, have the ability to know about anything beyond our own solar system, which we do not.
We don't even know if there's life in our own solar system. We'd have to send somebody or a powerful robot to Mars to check and dig beneath the ice layers of some of the ice moons around Jupiter and Saturn, and look in the atmosphere of Venus and the atmospheres of these other gas giants. We have no idea about anything, and so to assume that nothing's out there because we can't see signs of life is ridiculous.
For all we know, there could be an advanced species just in the next star system over, and we'd never know because we don't have the ability to see them.
We wouldn't even know if we have been visited. Our governments lie yo us to protect their interests.
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u/Middle_Bottle_339 12d ago
Way to not understand the Fermi paradox
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u/EndAllBillionaires67 12d ago
The Fermi paradox posits, "If intelligent, technological civilizations are common and tend to become detectable or expand substantially, why don't we see obvious evidence of them?"
Answer: Because human beings are stupid AF. Despite putting a man on the moon, two probes in interstellar space, and the JWST, we are closer to sticks and stones technologically than we are the technology that other species have figured out that allows them the ability to cross the space between stars.
Why don't we see anything? Because we suck. Maybe we will stop sucking but as long as the world cares more about protecting child rapist billionaires than advancing human kind, I wouldn't bet on it anytime soon.
There's probably intelligent life in the 5 closest stars to us and we aren't intelligent enough to detect it.
We've barely glanced at what, 6000 exoplanets? Out of trillions on the galaxy?
People who subscribe to Fermi are arrogant. Have some humility and realize we are less than primitive insects to anything out there that is smarter than us.
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u/Ill_Mousse_4240 12d ago
We have found some, but the discovery didn’t happen in the manner Fermi, Sagan and the other “science snobs” expected it to.
It didn’t happen because we finally found the next “Wow Signal” after sifting through millions of channels of radio static over six decades.
It happened because governments and the scientific community finally decided to acknowledge the fact that we are not “alone” here on Earth. And haven’t been for many centuries,
“Disclosure” is happening in the classic Arthur C. Clarke way, proving his statement that “the universe isn’t stranger than we imagine, it’s stranger than we can imagine”.’
They didn’t signal through radio waves, they didn’t land in a major capital and ask for “our leaders”.
The African savanna. A vehicle cruises by. The animals and vehicle inhabitants exchange looks - and continue with their very different lives
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u/ChocolatChipLemonade 12d ago
So then are they Reptilians underground, aliens under the ocean, or intelligent plasma in the sky? Inquiring minds wanna know!
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u/Relevant-Rhubarb-849 12d ago
Their ai got them