Each one of us, at least one time, asked to himself/herself
“Is there any life form up there?”
The vastness of the universe is so incredible that it is difficult even to grasp and, statistically speaking, it is highly implausible we are alone, considering that in the observable universe there are billions of galaxies which contains billions of stars, but if so… Why is the Universe so silent?
Here are some reasonable theories and hypothesis I found interesting. (N.B. These are a collection of hypothesis and speculations you won't find anything unscientific sold as absolute truth on this post )
The rare Earth Theory
Long story short: we are unique. Given all the requirement for carbon-based life to exist it may be improbable for sentient life to develop on a different planet. Hence, we are one of a kind.
The Great Filter Theory
Earth experienced 5 mass extinctions and yet it evolved complex life. What if other planets with the potential of developing life had less luck? An asteroid, solar flares or a near supernova blast could have destroyed life on other planets before they could have a chance to develop intelligent life.
The Early Birds
It is estimated that the universe is ~14.4 billion year old, the earth is ~4 billion years old and life started developing on earth as soon as the conditions for life were met. Dr. Peter Behroozi said that, compared to all the planets that will ever exist in the universe until the last star will burn out, the earth is quite early. We may be the first and not necessarily the last.
The Great Silence
The great silence hypothesis states that highly advanced intergalactic civilisations, capable of harvesting the energy of entire galaxies, may not be interested in insignificant humans who cannot even harvest efficiently the energy of their small sun.
The Vastness
The diameter of entire observable universe is ~92 billion light-years and the SETI project scanned just around 40.000 light-years around the Earth. Maybe the universe is too big for two sentient civilisations to ever meet each other.
Conclusion
If we are on the only planet which developed sentient life, given how huge our universe is, it becomes a creepy place, but if we think with a statistical mindset, being alone sounds highly improbable.
Maybe in our life time we will never know the answer to this great question, but we know we are alive and able to experience the vastness and the unknown of the universe.
Be curious, ask questions and look up, you’ll probably never see a spaceship, but you’ll certainly see why it is worth to seek.
