Our civilization is just too young in order for us to really make an impact in vast distances of space, we would need far superior and advanced technology to see/detect alien lifeforms.
Our current Observable Universe
Humans have only started broadcasting and transmitting signal from the last 60 years with advanced tools; our signal has only reached close to 200 light years.
There are about 125 billion (1.25Ã—1011) galaxies in the observable universe.
The closest known galaxy from Earth is the Canis Major Dwarf Galaxy, at 236,000,000,000,000,000 km (25,000 light years) from the Sun.
-We would need to invent faster ways of broadcasting signals to other lifeforms.
-Distances are soo vast that detecting signals requires many light years to travel distances that detect us and their civilizations. It takes millions and billions of years for light to travel to different Galaxies and vice versa. Distances are a huge constraint. The window time-frame is just too small or insignificant for us and them to really notice. Even if they are alive in our current times, light would take several hundreds, millions, even billions of years to travel to us and them. Earth would look like an exoplanet without life. If Intelligent Extra-terrestrials civilizations exist, light has travelled to us from so far that, we see their planet as inhospitable for life or likely shows life does not exist in that planet/star system. They would not know of our existence and we would not know of there existence.
Extraterrestrial view of our solar system
-A Type 3 or type 4+ civilization would not care about our existence since we are far too low as a species technologically and they would have evolved artificially into something else. They would think of us as similar to primates.
-Chances for an advanced alien civilization to reach a type 2â€“3 on Kardashev scale is highly unlikely/improbable due to disease, wars, famine, and catastropheâ€™s which would stop its advancements.
-For all we know, an extra-terrestrial civilization could be advanced enough that it could be living inside massive simulations hence, why we do not notice them nor they notice us.
-We are looking at wrong direction in space. Life could be likely thriving currently in other galaxies but we donâ€™t know where to look properly. An alien megastructure technology could be overshadowed by its own star, a neutron star, or even supernova explosions brightness. Instead of just looking at exoplanets, we need to broaden our horizons and look at other galaxies with more people working together to discover parts with alien planets.
-Intelligent life is EXTREMELY RARE perhaps in 1â€“2 digits within every galaxy or every other galaxy; Which is why we are not able to see signs of life because it took Earth 4+ billion years to develop intelligent species. Intelligent life might be younger than our civilization or does not exist yet in our galaxy. It is extremely unlikely we would ever be able to make contact.
-We NEED better and more powerful technology such as telescopes, radar signals, etc. for each planet orbiting a star to detect different energy frequencies and artificial alien megastructures within their home star. We need to have a clear picture to really see what is causing the energy fluctuations throughout different galaxies and within them stars and then planets to narrow down and pinpoint the search.
-Advanced extra-terrestrial civilizations method of communication, frequency, and detection is completely different and incomprehensible from our current understanding which is why we are not able to decipher potential signals coming our way. Alien civilizations could be using completely different methods of communication and we will not know since they are ahead of us by thousands perhaps millions of years in technology advancements.
-They have contacted us already; We just didnâ€™t notice. This could be a possibility since many conspiracy theories suggest that they may have contacted us but we havenâ€™t responded or they could be under our radars to observe and we would not recognize them or label their arrival as a natural cause or spores for explanation.
WOW signal detection in 1970â€™s
Even if aliens did have transmitters, the path loss, interference and other propagation effects are so significant that you may never detect an alien signal. The probability of detection is even worse when you consider that the Earth is spinning, orbiting and looks like a fraction of a dot from light years away. This means that antenna alignment is nearly impossible. Also depends upon how strong the connection of the signal traveling from many light years is properly received and interpreted given the allotted time period, makes it very, very, very difficult to see other alien lifeforms let alone civilizations.