The universe is about 90 billion light years in diameter, with at least 100 billion galaxies. This points to trillions of planets similar to Earth existing in many of these galaxies. And yet, we seem to be alone. We have sent out messages as a species deep into space… but no one responded. Where is everyone? What might be the reason for this silence?
This is called the Fermi paradox. To start off, everything outside our ‘local group’ has become out of reach forever as the universe continues to expand. We would have to already limit our scope to our own galaxy – The Milky Way, which consists of around 400 billion stars.
It is also estimated that a fifth of sun-like stars have planets very similar to Earth and situated in just the right habitable zone. If 0.1% of these planets had life, that would translate to a whopping 1,000,000 planets which can support life.
With the Milky Way being around 13 billion years old, the first habitable planets started to form after 2 billion years. That would give life several opportunities to form on a number of planets. And yet, there doesn’t seem to be anything. One possible explanation has to do with filters.
A filter is a limit which life has to surpass before it can advance to the next stage. What if alien life trying to get beyond its filter was annihilated? Or what it certain filters can never be surpassed by any form of life? Filters could be anything from ecological disaster to war to even a species killing pandemic.
But even if this was the case, there would at least be remains of alien civilisations floating around in space or just sitting on a different planet. Humans have already shaped the earth, with many objects set to outlive us for thousands of years. There is one scary alternative…
We could be the first forms of life. What if the reason why we haven’t detected anything yet is because there wasn’t anything to detect? What if we were the first conscious life in the entire local group, or maybe the universe itself? If this scares you, its okay.
Contemplating such cosmic proportions is bound to make us feel small and insignificant. But we really aren’t. If we are indeed alone, we have each other to experience the universe together. If we aren’t alone and it’s just a matter of time before we make contact, we can explore new ways of life together as well… with some new galactic neighbours.