This is a question that has perturbed humanity for decades now. From the start of the early space age during the Cold War, where asserting dominance in space was given the first importance, unknowingly, the USSR and the USA shaped the future. They made the then-present generation more involved with things regarding space. Many movies and TV Shows like Star Trek and others that focused on space travel and aliens came into being. They all portrayed Earth as just one planet among many in the universe. Movies also portrayed the Moon, Mars, and Venus all to the harbor with life. They were said to be aliens over there and that the government is just covering it all up. This led to a rise in a sort of cultist movement in the 70s, where people spread propaganda regarding the existence of “little green men” across the solar system.
But this is all just fanciful imagination. None of this is actually true as far as science is concerned with the present knowledge we hold. From the missions we have sent to the Moon, Venus, and Mars, there seems to be no sign of life. Moon and Venus are completely devoid of any signs of a life-supporting system, and it is theorized that Moon and Venus cannot have supported life anytime in the past. However, as for Mars, there is proof suggesting that water may have flowed on the surface of Mars sometime in the past. This is because Mars has canyons and shorelines, which are being mapped, and simulations have shown that there was a high possibility that water may have once flowed on Mars. But this doesn’t necessarily mean that life is still there now. They may or may not have been life forms on Mars. But, if we find any one of them now, it would be in the form of microbes, not fully evolved conscious beings like us. Some missions are ongoing to find out if there are any fossils of Martian microorganisms. If there are, that would be the first sign that we are not ( at least, were not ) alone in this universe.
There have also been speculations that there is a very high possibility that alien life forms exist in the very galaxy that is much more advanced than us but does not interfere with us mainly because we are not worth noticing. A suitable analogy would be a man not noticing the worms or ants beneath him when walking through a forest. ( We are the ants! ) We are just not worthy of any form of attention from these alien civilizations.
The Drake Equation states that there are probably 1000 to 100,000,000 planets in our very galaxy that can harbor alien civilizations. But even with so many planets, the only thing we are receiving from outer space is dead silence. There has been a separate organization called SETI ( Search for Extraterrestrial Intelligence ) which searches the sky for any signals which are out of the ordinary. There has been only one such signal called the WOW signal, which was way out of the ordinary, but scientists have ruled it out as a piece of signal from Earth that was bounced back from space debris. There has been nothing that even shows the slightest hint of an extraterrestrial civilization.
This has been really dreadful to scientists. There is a high probability that humankind is well and truly alone in this entire vast universe. That we are the last ones left alive here. There is no one beside us. If there were, then they are truly gone. Even knowing that this is the highest possibility we live in fills me, the author, with some sense of extreme loneliness. Are we really the last living thing in this entire vast universe? If so, then the best we can do is to survive and thrive. Regardless, the search for extraterrestrial life will never stop. Even if all other life is dead, we will still try to find out what they were and how they vanished.