The Universe is much more vast than we can imagine. It has been expanding for over 13.8 billion years, and some of the very light we observe in the night sky is older than earth itself. And with simple life easy to assemble, and the vast numbers of planets out there, we are forced to wonder. Are we alone? And if not, where is everybody? Well the answer is fascinating, and in some cases, quite terrifying indeed.
“I’m sure the universe is full of intelligent life. It’s just been too intelligent to come here.” – Arthur C. Clarke, Futurist and Writer.
The Fermi Paradox and Kardashev Civilisations
‘In space, no one can hear you scream’ – Alien, 1979
The paradox posed by the apparent absence of intelligent life is called ‘The Fermi Paradox‘. According to the ‘Drake Equation‘, a mathematical prediction of the number of intelligences out there, there should be at least 100,000 species with advanced civilisations.
To speak of ‘Advanced’ civilisations we must first define them. The Kardashev Scale helps us to understand civilisations by their level of energy use. To summarise it quickly, the higher the number, the more advanced the technology and greater the chance the species can travel across the Universe:
- Type 0: Fails to completely harness power of local planet (us!)
- Type 1: Harnesses power of local planet (interplanetary species.)
- Type 2: Harnesses power of local star (interstellar species.)
- Type 3: Harnesses power of resident galaxy (intergalactic species.)
Alongside the energy use and travel, each jump up the ladder is presented with new challenges. And part of this challenge is why we may not see life out there. With earth relatively young (4.5 billion years or so old,) and the universe so vast, some species may have billions of years head start. So why don’t we see intergalactic fleets? Where is the hidden message from the stars?
We approach the great filters.
Great Filters Of Life
“I felt a great disturbance in the Force, as if millions of voices suddenly cried out in terror and were suddenly silenced.” – Obi Wan Kenobi, Star Wars IV
A ‘Great Filter‘ is a concept designed to explain the paucity of life in the Universe. It is a barrier to a species survival, and its nature is variable dependent on time. And depending on where in the species’ life it appears, it could easily explain our cosmic quandary. And if its happens late, offers a stark warning.
If a filter is early, say, at the transition from single celled to multicellular life, then we have done very well. We have overcome the major universal hurdle. But it also means that intelligent and complex life is exceedingly rare, and conversely single celled life could be everywhere. And given the distance of our nearest stars, and the time period we have been looking, chances are that us spotting another species is pretty much zero.
They are either very far away and their signals or ships have not reached us yet (consider that even at light-speed our nearest star is 10,000 years away,) or something else has claimed them in the mean time. They could have existed 10 billion years ago, and simply died out in a quiet corner far away.
The second most discussed time for a great filter is the transition from a type 0 to type 1 civilisation. At this time a species is likely playing with very dangerous energies, but still subject to internal warfare, religious zealotry and nationalism. It may very well be that no one ever gets this far, as they blow themselves up before they can. Who knows how many potential galaxy faring species have been wiped out in their own nuclear war?
I mean look at us, the leader of the free world is goading a nuclear power with Tweets.
Lost In Transition
“Can there be any question that the human is the least harmonious beast in the forest and the creature most toxic to the nest?” – Randy Thornhorn, Author.
For us as humans, this is quite concerning. If the great filter is placed here, and the universe is silent, then our chances are pretty low. If in the whole of space time, given even the most restrictive metrics, we hear nothing, then it means most species cannot survive becoming a Type 1 civilisation. We assume here that the transition between 1-2, or 2-3, is easier as war is less likely. But yet, we see nothing to reassure ourselves.
It says something quite profound about intelligence. If life cannot readily pass this transition, it means that intelligence hits a wall. The intraspecies dynamics are too complicated to allow for general progress. The stupid wins out. Its not hard to imagine a far off civilisation annihilating itself over resources, religion or power struggles.
We are judgemental, prone to violence, capricious and short-sighted. If we imagine any of these species to behave like us, it tells a sad story.
But Have Hope
The Great filter only talks about survival, not intent and behaviour. The Universe could be teeming with intelligent life, but we haven’t seen it yet. And there could be good reasons for that.
Perhaps ‘they’ are already here, but we cannot see them. This could be because we simply don’t know what we are looking for. Radio waves are pretty simple, and an advanced species may have moved onto something more reliable. Our skies could be filled with alien messages, ranging from the profound to intergalactic cable, and we would have no idea.
They may not want to see us. Maybe they will only talk with Type 1+ civilisations, because anything less is a waste of time or dangerous. We wouldn’t extend a hand to a lion, so why would they consider us any better? We haven’t proved we can be peaceful even amongst ourselves. An alien species would consider this option very seriously.
Or perhaps it simply isn’t worth it. Travelling interstellar distances takes generations of time and is likely very costly, and what can we offer? New technology, unlikely? Resources? Its probably cheaper to mine local asteroids. Philosophy, art, music? Perhaps, but what intergalactic government will commission an art research grant tantamount to a million year field trip?
Are We Alone?
‘The universe is a pretty big place. If it’s just us, seems like an awful waste of space.” – Carl Sagan, Contact
Given what we know about the Universe, it seems very unlikely. Simple molecular life is probably not uncommon, but the absence of intelligent life is less reassuring. We may indeed be heading toward a fiery fate, or perhaps will be the first interstellar species out there. One day we might bypass Voyager 1 and say ‘Hello’ to ET first hand (or claw,) but for now it doesn’t seem too likely.
But don’t take it too hard. The Universe is grand, time long and life likely easy. There may be something out there, asking just the same questions. And one day, with a smidge of luck, we can answer those questions for them. Unless we decide to blow them up.
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- Learn more about great filters in this handy video by Kurzgesagt
The opinions expressed in this article are those of Dr Janaway alone and may not represent those of his affiliates. Image courtesy of Robert Sullivan
The above sources are true as of 18/3/17. If you would like to discredit them, feel free. It brings us closer to the truth, and I can always cry about it later.